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exchange and transport Flashcards

1
Q

what do living organisms need to keep them alive?

A

oxygen, water, glucose, amino acids, minerals

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2
Q

what do living organism need to get rid of?

A

carbon dioxide urea, creatinine

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3
Q

factors that affect the need for exchange systems

A

size of organism/ SA:Vol ratio/ diffusion distance
metabolic rate
endotherm/exotherm

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4
Q

unicellular vs multicellular organisms

A

unicellular e.g. amoeba has lower metabolic rate (lower demand for O2 and glucose), simple diffusion takes place across its plasma membrane e.g. O2: this is sufficient bc of short diffusion distance, so it can rely on simple diffusion alone and doesn’t need a specialised exchange surface
multicellular e.g. dolphin has small SA:Vol ratio and large diffusion distance, higher metabolic rate (very active), so have higher O2 demand and are endotherms so maintain body temp. therefore they have a specialised exchange surface (alveoli in lungs)

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5
Q

as an organism gets bigger, what means it needs a specialised exchange surface/ transport system?

A

as an organism gets bigger, it becomes more difficult for it to exchange substances across its outer surface, so it therefore needs a transport system which allows them to survive

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6
Q

as size of organism increases, what happens to its SA:vol ratio?

A

SA:Vol decreases

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7
Q

why do small organisms not require a specialised exchange surface or transport system?

A

e.g. unicellular amoeba
large enough SA:Vol for exchange to take place over their surface
all the cytoplasm is very close to the environment in which they live and so diffusion will supply oxygen etc

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8
Q

circumference of circle equation

A

2π r

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9
Q

area of circle equation

A

π r^2

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10
Q

surface area of cuboid equation

A

2(bh+bl+hl)

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11
Q

volume of cuboid equation

A

hbl

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12
Q

features of an efficient exchange surface??

A

large surface area
thin
good blood supply/ventilation
moist
permeable

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13
Q

why does an efficient exchange surface have a large surface area?

A

maximum number of molecules can diffuse per unit time

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14
Q

why is an efficient exchange surface thin?

A

reduced diffusion distance so faster rate of diffusion

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15
Q

why does an efficient exchange surface have good blood supply and/or ventilation?

A

maintains steep concentration gradient

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16
Q

why is an efficient exchange surface moist?

A

enables gases to dissolve
protects cells from drying out

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17
Q

why is an efficient exchange surface permeable?

A

gases can diffuse through cell membrane

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18
Q

what makes alveoli an efficient exchange surface?

A

large SA so max. no. of CO2 and O2 molecules can diffuse per unit time
alveolar walls are 1 cell thick (squamous epithelium cells= thin) so reduced diffusion distance
good blood supply, maintaining steep conc. gradients of O2 from alveoli into capillaries and CO2 from capillaries to alveoli (partial pressure gradient)
have moist lining (lung surfactant), enabling case to dissolve in it and then diffuse
permeable walls so gases can diffuse through.

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19
Q

property of water within alveoli

A

water has high surface tension bc the H2O molecules on the surface are pulled together by strong H bonds

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20
Q

what is pulmonary surfactant?

A

a mixture of lipids and proteins which is secreted into the alveolar space by epithelial type II cells

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21
Q

pulmonary surfactant function?

A

lowers the surface tension at the air/liquid interface within the alveoli of the lungs
this stops the walls of the alveoli sticking together and collapsing as we exhale

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22
Q

what happens when someone has respiratory distress syndrome?

A

no surfactant produced so high surface tension
alveoli stick together
cannot take breath
e.g. in newborn babies

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23
Q

what does pO2 stand for?

A

partial pressure of oxygen

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24
Q

what is partial pressure of oxygen?

A

concentration of O2 in a mixture of gases related to the pressure it contributes

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25
Q

summarise the exchange of O2 and CO2 that takes place as the blood flows past an alveolus in mammalian lung

A

blood in pulmonary capillaries has lower pO2 and higher pCO2 than alveolar air
gases move across respiratory membranes down pressure gradients
O2 enters blood
CO2 diffuses from pulmonary capillaries into alveolar air and is eliminated during expiration

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26
Q

where does the newly oxygenated blood from pulmonary capillaries go?

A

it is gathered into pulmonary vein, transported back to heart and then enters systematic circulation via aorta.

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27
Q

how much oxygen diffuses into the blood per minute at rest?

A

250cm3

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28
Q

why is blood only 95% saturated with oxygen when it leaves the pulmonary capillaries?

A

some air inhaled does not take part in gas exchange e.g. in trachea, bronchi, nose (dead space)
some of the blood in the lungs doesn’t go through any alveolar capillaries e.g. bronchial circulation from aorta returns via pulmonary vein

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29
Q

pO2 in:
inspired air
alveolar air
blood entering pulmonary capillary
blood leaving pulmonary capillary

A

160
104
40
104

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30
Q

pCO2 in:
inspired air
alveolar air
blood entering pulmonary capillary
blood leaving pulmonary capillary

A

0.3
40
45
40

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31
Q

nasal cavity conditions and why

A

good blood supply to warm air
humid environment so airways don’t dry out

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32
Q

pleural fluid functions

A

decreases friction to protect delicate lungs
transmits pressure gradients

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33
Q

ciliated epithelium function

A

trachea & bronchi= lined with ciliated epithelium
goblet cells secrete mucus which traps dust/pathogens
cilia beat in a synchronised pattern to waft the mucus to the pharynx where it can be coughed up/ swallowed
prevent disease

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34
Q

are inspiration and expiration passive or active?

A

inspiration= active
expiration=passive

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35
Q

mechanisms of breathing: inspiration

A

external intercostals contract
ribs move up and out
diaphragm contracts, moves down & becomes flatter
thorax volume increases and pressure decreases
air drawn in (bc ATM exceeds lung pressure)
internal intercostals relax
elastic fibres stretch

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36
Q

mechanisms of breathing: expiration

A

external intercostals relax
ribs move down and in
diaphragm relaxes, moves up, becomes dome-shaped
thorax volume decreases so pressure increases
air expelled (lung pressure exceeds ATM)
internal intercostals contract
elastic fibres recoil

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37
Q

mechanisms of breathing: expiration

A

external intercostals relax
ribs move down and in
diaphragm relaxes, moves up, becomes dome-shaped
thorax volume decreases so pressure increases
air expelled (lung pressure exceeds ATM)
internal intercostals relax
elastic fibres recoil ( to expel air)

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38
Q

what is breathing controlled by?

A

involuntary control (autonomic nervous system) carried out by breathing/respiratory centre in the medulla oblongata

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39
Q

how does breathing rate increase (in terms of control)

A

chemoreceptors bind to sensory neurone
travels to breathing centre in brain
to motor neurone
to muscles involved in breathing, which increase rate and depth of breathing

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40
Q

why is forced expiration an active process?

A

internal intercostals contract pulling the ribs down hard and abdominal muscles contract forcing the diaphragm up to force air out of the lungs more forcefully
requires energy from respiration

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41
Q

where is cartilage present in the lungs?

A

trachea as ‘C’ shaped rings
bronchus: arranged in plates
in some larger bronchioles
NOT alveolus: would prevent it stretching

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42
Q

cartilage function in lungs

A

SUPPORT
strong so prevents collapse of trachea, bronchi & bronchioles
flexible so trachea & bronchi can bend & extend
“c” shaped rings allow oesophagus to expand behind trachea

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43
Q

where are goblet cells present in the lungs?

A

trachea
bronchi

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44
Q

goblet cells function

A

CLEANING
secrete mucus, which contains glycoproteins (traps dust and pathogens)

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45
Q

where are ciliated cells present in the lungs?

A

trachea
bronchi
bronchioles

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46
Q

ciliated cells function

A

CLEANING
cells with hair-like projections which beat to waft mucus up the airway
require energy as ATP

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47
Q

where is smooth muscle found in the lungs?

A

trachea
bronchi
bronchioles
NOT alveolus bc they must maintain short diffusion distance

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48
Q

where is smooth muscle found in the lungs?

A

trachea
bronchi
bronchioles
NOT alveolus bc they must maintain short diffusion distance

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49
Q

smooth muscle function

A

contracts to constrict airway (e.g. if harmful substance in air)
relaxes to dilate airways to increase airflow to alveoli

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50
Q

where are elastic fibres found in the lungs?

A

trachea
bronchi
bronchioles
alveoli

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51
Q

elastic fibres fucntion

A

IN BRONCHIOLES: stretch when SM contract to constrict airway
recoil when SM relaxes to dilate airway
IN ALVEOLI: stretch to allow alveoli to expand (prevents bursting)
recoil to expel air

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52
Q

where is squamous epithelium found in the lungs?

A

only alveoli

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53
Q

squamous epithelium function

A

EXCHANGE
thin, flattened cells to give short diffusion distance for increased rate of gas exchange

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54
Q

small blood vessels in lungs function?

A

supplies cells with oxygen, especially ciliated epithelium bc beating requires energy

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55
Q

what is this?

A

a spirometer

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56
Q

why does the subject of a spirometer wear a nose clip?

A

to prevent breathing in & out of nose

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57
Q

what does the chamber in the spirometer contain?
why?

A

medical-grade oxygen so it floats on the surface of the tank
O2 will get used up over time so lid will fall

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58
Q

purpose of soda lime in a spirometer?

A

absorbs carbon dioxide

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59
Q

what does the rotating drum in a spirometer produce?

A

a kymograph

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60
Q

how does a spirometer work?

A

breathe out into tank (upper half will rise)
breathe in from tank (upper half will fall)
tracemarker is attached to the mobile upper half connected to kymograph which record change in oxygen

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61
Q

how to measure tidal volume from a spirometer volume vs time graph?
how to measure oxygen consumption

A

peak to trough
draw tangent from first to final peak and make triangle

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62
Q

why does the total volume in the tank decline in a spirometer?

A

subject uses up O2 from the tank due to gas exchange in alveolus
soda lime absorbs any CO2 expired

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63
Q

why does exhaled air contain some/less O2?

A

contains less O2 than inhaled
some inhaled air doesn’t reach alveolus
so we breathe this O2 out

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64
Q

what does inhalation mix fresh air with?

A

inhalation mixes fresh air with stale air= residual volume left in lungs from previous breath

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65
Q

what is this?

A

a spirometer trace

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66
Q

a health campaigner claims that giving up cigarettes improves lung function. evaluate this claim

A

FOR:
FEV1 is around 2L lower for COPD patients, which could suggest lung function is better in non-smokers
COPD patients volume plateaus at lower quantity
AGAINST:
no info about control variables e.g. age, gender which may affect FEV: invalid practical
COPD may be caused by other factors/ not told COPD patient is a smoker. may be due to work hazard e.g. breathing toxic chemicals
sample size too small to be sure of this claim
no data from patients which have given up smoking so no evidence that FEV would increase
other respiratory conditions not taken into account
repeats, means, statistical tests

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67
Q

why do large, active organisms need a specialised exchange surface for gaseous exchange?

A

have small SA;Vol ratio
active organisms have a high demand for oxygen
diffusion distance is too great so diffusion takes too long

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68
Q

the lungs are surrounded by the diaphragm and intercostal muscles. how does this improve the efficiency of gaseous exchange

A

enables ventilation to supply O2 to alveoli & remain CO2

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69
Q

describe the features of the lungs that make them effective organs for gas exchange

A

many alveoli to give large SA
alveolar wall & capillary wall both 1 cell thick (so thin) so short diffusion distance
good blood supply/many capillaries maintains steep conc grad
contains elastic tissue to stretch & recoil to expel air
good ventilation maintains steep conc. grad. for O2

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70
Q

features of alveoli which make them suitable for gas exchange

A

large SA so more O2 can diffuse
thin/1 cell thick so short diffusion distance
elastic tissue recoils to expel ar
moist so gases can dissolve

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71
Q

why is it necessary for amoeba to divide once it reaches a certain volume

A

as amoeba grows, diffusion distance for O2 increases
central regions of amoeba are O2 deprived unless division reduces size

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72
Q

tidal volume definition
normal tidal volume

A

volume of air that flows in & out of the lungs with each breath during quiet breathing (usually measured at rest)
around 0.5dm3 (but only 0.35dm3 reaches alveoli)

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73
Q

vital capacity definition
normal vital capacity

A

maximum volume of air that can be moved by the lungs in one breath (strongest possible exhalation followed by strongest possible inhalation)
2.5-5dm3

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74
Q

inspiratory reserve volume definition

A

maximum volume of air that can be inspired in excess of the tidal volume

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75
Q

expiratory reserve volume definition

A

maximum volume of air that can be expired in excess of the tidal volume

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76
Q

residual volume definition
normal residual volume

A

volume of air left in the lungs after maximum forced expiration
1.5dm3

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77
Q

total lung capacity defintion

A

total volume of air in lungs after maximum inhalation (total volume of air that lungs can hold)

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78
Q

how to calculate oxygen consumption

A

gradient of graph (change in y over change in x)
per second (multiply x60 to get per minute)

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79
Q

how to calculate tidal volume

A

take the mean average of >3 readings from peak to trough of breaths

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80
Q

how to calculate breathing rate

A

count the number of full breaths in 1 minute

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81
Q

what does a steeper gradient on a O2 used vs time graph mean?
when may this happen?

A

higher O2 demand due to higher breathing rate and deeper breaths e.g. during exercise

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82
Q

what is pulmonary ventilation rate and how do you calculate it?

A

total air breathed per minute
tidal volume x breathing rate

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83
Q

how can athletic training affect the condition of the lungs?

A

more efficient: improved network of pulmonary capillaries so more oxygen taken up
slightly increased lung volume
increased alveoli size
increased strength in muscles so can breathe in more air for a longer time period
faster breathing rate so more oxygen per second
higher tidal volume

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84
Q

do all fish need to swim constantly in order to breathe?

A

no

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85
Q

do fish have lungs as well as gills

A

NO
except lungfish

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86
Q

do fish get their oxygen and food at the same time via mouthfuls of water?

A

yes

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87
Q

do whales and dolphins have lungs?

A

yes

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88
Q

what problems do fish have regarding gas exchange?

A

fish have small SA;Vol ratio bc they are multicellular and fairly large therefore diffusion via skin would take too long bc distance is too great
water=1% O2, air=21% O2. in warmer water, solubility of O2 decreases so fish need specialised exchange surface
multicellular and active so fairly high metabolic rate (but they are ectotherms so cannot increase metabolic rate to maintain temp: demand for O2 slightly lower than endothermic organisms of the same size)
water is 100x thicker and 1000x denser than air, so requires more energy to cross gas exchange surfaces. (water only flows over gills in one direction)
O2 diffuses 8000x faster in air compared to in water

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89
Q

how many pairs of gills do fish have?

A

3-5 pairs

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90
Q

what are the gills covered by?

A

a bony plate called the operculum

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91
Q

what are gill rakers made of
gill rakers function

A

bone or cartilage to prevent food particles reaching gill filaments and obstructing gas exchange

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92
Q

distance between 2 lamellae?

A

50 micrometres

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93
Q

what prevents lamellae from collapsing?

A

water

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94
Q

what must happen for fish to get water to flow over their gills?

A

the pressure in the buccal cavity must be greater than the flow in the opercular cavity

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95
Q

how does the structure of gills relate to their function?

A

lots of filaments and lamellae so large SA so increased rate of diffusion of O2/CO2
filaments and lamellae have thin walls so short diffusion distance between blood and water to increase rate of diffusion of O2/CO2
filament tips overlap to increase resistance to flow of water, giving time for diffusion of gases
good blood supply via capillary network in the lamellae maintains steep conc grads
countercurrent flow (water flows in opposite direction to blood in lamellae), maintains the conc grad across full length of gill

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96
Q

describe and explain the countercurrent system in fish

A

counter current means water and blood flow in opposite directions
this ensures concentration of O2 in the water is always higher than in the blood so con grad is maintained across the full length of the gill
more oxygen will diffuse into the blood

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97
Q

describe mechanism of inspiration in a fish

A

mouth open and operculum closed
floor of buccal cavity lowers (muscles involved so active) so volume increases so pressure decreases
water flows in via the mouth down a pressure gradient
sides of opercular cavity start to bulge outwards (muscles involved so active), so volume of cavity increases and pressure decreases
mouth closes and buccal cavity rises, decreasing volume and increasing pressure
pressure higher in BC than OC is water is forced to flow over the gills down a pressure gradient

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98
Q

describe mechanism of expiration of a fish

A

sides of opercular cavity move inwards
operculum/opercular valve opens
water is expelled

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99
Q

use of mechanism of fish ventilation

A

water only flows in 1 direction over the gills and out

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100
Q

general insects facts ab gas exchange

A

tough exoskeleton so no exchange via skin
fairly large SA:vol ratio. fairly small organisms
active and multicellular so have certain O2 demands
short diffusion distance so rely on simple diffusion via tracheal system
circulatory system is separate from their gas exchange system
no blood pigments

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101
Q

what are spiracles

A

microscopic parts of an insect which can be opened and closed

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102
Q

parts of an insect

A

head
thorax
abdomen
wings
spiracles

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103
Q

tracheae adaptions in insects

A

held open by chitin
enables O2 and CO2 to diffuse down the tracheae

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104
Q

tracheoles adaptations

A

lots of them increases SA for diffusion
0.1 micrometre thin walls for short diffusion distance
tracheole fluid at ends of tracheoles. O2 dissolves into this and diffuses through it
ends of tracheoles are within muscle tissue so short diff. distance

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105
Q

how do insects maintain rates of diffusion when they are active?

A

muscle respire anaerobically and produce lactic acid, decreasing water potential so tracheole fluid is drawn into muscles by osmosis
this draws more air in and exposes more surface air of walls for more diffusion
increases rate of diffusion

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106
Q

open vs closed spiracles

A

OPEN: hairs are sensory and also trap humid air so decrease water potential to decrease water loss
CLOSED: less gas diffusion/ventilation and less water loss (air sacs along tracheae to store O2 when spiracles are closed)

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107
Q

ADAPTATIONS OF INSECTS FOR EFFICIENT GAS EXCHANGE

A

size of spiracles can be changed to draw air in or out
larger insects may use abdominal muscles (ATP needed) to cause pressure changes to draw air into tracheae system
during flight, wing movement can cause change in thorax shape to draw more air in
insects= small size so short diff. distance so simple diff. is sufficient
O2 diffuses slowly through tracheal fluid but during activity, muscles resp. anaerobically to release lactic acid, decreasing water potential is fluid moves into muscles by osmosis, increasing rate of diffusion
air sacs can store O2 to be used when spiracles are closed
some insects have external gills
lots of tracheoles increases SA
tracheole ends in muscles for short diffusion distance
tracheae held open by chitin enables O2 to get to exchange surface

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108
Q

why will we never see giant insects?

A

larger insects would have higher O2 demand, small SA:vol and larger diff distance so simple diffusion not sufficient for supply to tissues/cells

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109
Q

large surface area adaptation in insects, fish and humans

A

INSECTS: many tracheoles
FISH: many lamellae and filaments
HUMANS: many alveoli

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110
Q

maintaining conc gradients in insects, fish, humans

A

INSECTS:ventilation of abdomen by pumping air in. air sacs. open/close spiracles
FISH: counter-current flow, buccal pumping
HUMANS: blood flow past alveoli. ventilation brings more O2 and removes CO2

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111
Q

short distances for gas exchange in insects, fish, humans

A

INSECTS:ends of tracheoles penetrate muscle tissue. walls are 0.1 micrometer thin
FISH:filaments and lamellae have thin walls. capillaries inside filaments
HUMANS: squamous epithelium makes up alveoli and capillary walls. one cell thick

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112
Q

good blood supply adaptations in insects, fish, humans

A

INSECTS: n/a
FISH: rich blood supply, capillary network, gill filaments
HUMANS: capillary network surrounds alveoli

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113
Q

factors that affect the need for a transport system?

A

size
SA:vol
level of activity
body temperature

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114
Q

how does size affect the need for a transport system?

A

small animals do not need a transport system bc all cells r surrounded by/nr. env.
simple diffusion alone supplies enough O2/nutrients to meet demand
several layers of cells, internal distances= too great for diffusion to be effective & O2/nutrients= used up by outside layers

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115
Q

how does SA:vol affect the need for a transport system?

A

small animals have large SA:vol but large animals usually have small SA:vol
insufficient O2/nutrients supplied to internal cells bc distance too great so diffusion takes too long
can be solved by changing shape e.g. flatworms=v. thin and have large SA:vol

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116
Q

how does level of activity affect the need for a transport system?

A

active animals need more energy and therefore a faster rate of respiration
C6H12O6+6O2->6CO2+6H2O+ energy

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117
Q

how does body temperature affect the need for a transport system?

A

endotherms (warm blooded animals) e.g. birds/mammals maintain their body temp at a constant level often higher than surrounding temps so have higher energy demand so increased rate of resp
ectotherms (cold blooded) e.g. fish/reptiles/amphibians rely on heat from environment to increase body temp so have lower energy demand

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118
Q

what do large. multicellular organism need a transport system for?

A

transport nutrients (minerals, O2, glucose, amino acids, fatty acids, glycerol)
transport waste e.g. CO2, urea
SOME transport hormones and anitbodies

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119
Q

why do small simple organisms not require a transport system?
examples

A

large SA:vol & short diffusion distance so rely on simple diffusion
low energy demands
e.g. amoeba, sponges jellyfish

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120
Q

why do large multicellular organism require a transport system?
examples

A

large, active so high metabolic rate so higher demand for O2, glucose and removal of waste
small SA:vol and large diffusion distance too great to meet demand for nutrients

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121
Q

basic components of a circulatory system?

A

circulating fluid
pumping device
blood vessels
valves
input form an exchange surface
circuits

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122
Q

basic components of a circulatory system: circulating fluid

A

often called the blood w/ respiratory pigment Hb
often used to carry oxygen, glucose, hormones, urea, CO2

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123
Q

what respiratory pigment do insects have?

A

haemolymph

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124
Q

basic components of a circulatory system: pumping device

A

e.g. heart
creates pressure difference which forces blood flow

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125
Q

basic components of a circulatory system: blood vessels

A

blood is at least partially contained in tubes to carry it towards tissues and back to the heart

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126
Q

basic components of a circulatory system: valves

A

allow blood flow in correct direction
prevent back flow (particularly important where blood is at low pressure)

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127
Q

basic components of a circulatory system: input from exchange surface

A

enables oxygen and glucose to enter the blood capillaries and waste to be removed

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128
Q

basic components of a circulatory system: circuits

A

sometimes one circuit e.g. fish
sometimes there are 2 circuits: one to pick up O2 and one to deliver it e.g. in humans

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129
Q

closed circulatory systems w/ example

A

in closed circulatory system, blood is fully enclosed within blood vessels at all times so high pressure and rapid flow can be maintained, giving greater control over distribution
valves also maintain flow in 1 direction
EG fish, mammals, amphibians, birds

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130
Q

open circulatory systems w/ example

A

heart pumps haemolymph through short vessels into a large cavity called a haemocoel
the haemolymph directly bathes tissues, enabling diffusion
fluid is not enclosed within blood vessels so it moves slowly and at low pressure in the cavity (due to the movement of the organism)
inefficient bc little control over direction of circulation
when heart relaxes, haemolymph is sucked back via pores called Ostia
EG insects, molluscs

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131
Q

how to carry out dissection of an insect?

A

cut open exoskeleton of insect
stain tracheoles with methylene blue

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132
Q

explain why bone is described as a tissue and gills are described as organs?

A

bone performs one/few functions
tissue has one/few types of cells
gills contain blood/bone/epithelial/connective tissue

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133
Q

precautions taken when using a spirometer?

A

use nose clip
use medical grade oxygen
ensure no medical problems e.g. asthma
disinfect mouth piece

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134
Q

compare mechanism of normal expiration with forced expiration of the lungs

A

external intercostals relax, diaphragm relaxes, elastic recoil
passive
internal intercostals contract-> ribs pulled down
abdominals contract to force diaphragm up
active

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135
Q

describe how to use a spirometer to measure the tidal volume of a person

A

nose clip
patient breathes in and out
resting/quiet breathing
switch on chart recorder and calculate volume on chart

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136
Q

what type of circulation is more efficient?
why?

A

closed
open: blood loses pressure in body cavity, cannot regulate direction of blood flow

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137
Q

why are open circulatory systems sufficient for insects?

A

they are small
they have a separate system for oxygen transport

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138
Q

advantages of closed circulatory system

A

higher pressure
rapid flow maintained
greater control of distribution

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139
Q

compare open vs closed circulatory system:

A

OPEN= few blood vessels. CLOSED=blood is enclosed within blood vessels
OPEN= lower blood pressure
OPEN e.g. locust, transport system is haemolymph. CLOSED= blood containing haemoglobin
OPEN insect, haemolymph carries waste nitrogenous products, defence cells, food. CLOSED fish= carries CO2 and O2 too
CLOSED= more efficient; supply&elimination is faster
OPEN has haemocoel. absent in CLOSED
OPEN: blood in direct contact with tissues&cells.CLOSED: exchange via diffusion through blood vessel walls
CLOSED=exchange in capillaries. none in OPEN
BOTH have heart to pump transport medium around

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140
Q

describe single circulation with an example?

A

blood passes to the heart only once during complete circulation of the body
fish

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141
Q

disadvantage of single circulatory system

A

pressure drops in gill

142
Q

why is a single circulatory system sufficient for fish?

A

they gain support from the water
they are ectotherms so have lower energy needs and less demand for oxygen and glucose

143
Q

describe double circulation with examples

A

blood passes through the heart twice during complete circulation of the body
pulmonary and systemic circuit
birds, mammals, amphibians

144
Q

advantages of double circulation

A

blood pressure is maintained as blood is re-pressurised by heart
different pressures can be achieved in pulmonary and systemic circuit, preventing damage to lungs
can meet higher metabolic demands

145
Q

what happens in heart of amphibians?

A

ventricle mixing of oxygenated and deoxygenated blood
less oxygen to the body

146
Q

why is frog system less effective at supplying body with oxygen?

A

blood will not be fully oxygenated
lower pressure
may still be carrying oxygen

147
Q

complete vs partial double circulation

A

PARTIAL=only 3 chambers, ventricles not separated and oxy/deoxy blood not fully separated
BOTH= double bc blood passes 2x through heart for each complete circulation. both have pulmonary and systemic systems

148
Q

compare mammals/birds, amphibians and turtles circulatory systems

A

MAMMALS: oxy & deoxy blood do not mix. DO in other 2
MAMMALS have 4 chambered heart w/ 2 atria and 2 ventricles. TURTLES/AMPHIB have 3 chambered heart w/ 2 atria and one ventricle (partially separated ventricle in turtles)
ALL 3 are doubel circulatory systems where blood passes through heart twice in 1 full circulation
ALL 3 are closed systems w/ blood vessels
ALL 3 have a heart to pump blood
ALL are effective but MAMMALS are most efficient at delivering fully oxy blood to body
TURTLES/AMPHIB are ectotherms. MAMMALS are endotherms so have higher metabolic rate/higher O2 demand bc they must maintain body temp
TURTLE/AMPHIB have less O2 available to body cells but AMPHIB system is sufficient bc they cna absorb O2 through skin. TURTLE heart has folds and grooves ventricular chamber, so partially separated and less oxy/deoxy mix

149
Q

compare single and double circulation

A

single=1 circuit. double=2 circuits: pulmonary and systemic
single=BP low when it reaches body tissues bc already gone through 1 set of capillaries.double= faster bc comes back to heart before pumped to systemic tissues
single: heart is a single pump. double: heart is double pump
single=less efficient than double
single=successful in fish bc ectotherms and don’t support own weight BUT animals need double bc higher metabolic needs/rate
single: BP limited by delicate nature of gills but double: control BP in lungs so high in systemic and low in delicate pulmonary
animals w/double=more active bc blood reaches respiring tissues faster due to higher pressure
in 1 complete cycle, blood in double passes through heart2x but only 1x in single
both have heart to pump. single=2 chambers. double=3 or 4

150
Q

size of heart?

A

12cm long

151
Q

structure of heart?

A

4 chambers
2 thin-walled atria and 2 thicker walled ventricles
heart is formed of mainly cardiac muscle-the myocardium
heart also has inner epithelial lining, the endocardium and an outer covering, the pericardium

152
Q

what do the AV/SL valves do & how

A

prevent back flow of blood
valve tendons and papillary muscles prevent the valves turning inside out

153
Q

what is the cardiac cycle?

A

a sequence of events which makes up one heartbeat
the chambers of the heart contract in a certain sequence so that they pump the blood efficiently

154
Q

how long is each cardiac cycle?

A

about 0.8 seconds

155
Q

what are the stages of the cardiac cycle?

A

cardiac diastole
atrial systole
ventricular systole

156
Q

briefly, what is diastole?

A

resting period
atria and ventricles are relaxed

157
Q

describe what happens during diastole

A

blood under low pressure enters atria from pulmonary vein and vena cava
atria fill w/ blood and become distended
initially bi/tricuspid valves shut, but as atria fills w/ blood, pressure in atria increases and eventually exceeds that of the ventricles, causing the AV valves to open.
some blood flows into the relaxed ventricles
semilunar valves shut as pressure in aorta/PA is larger than in the ventricles

158
Q

briefly what is happening in atrial systole

A

`atria contracting

159
Q

describe atrial systole

A

atria contract simultaneously, pressure in atria rises, more blood flows into ventricles
contraction of atrial walls seals of vena cava and PVs, preventing back flow of blood into veins as pressure in atria increases

160
Q

why do atria have thinner walls than ventricles?

A

they only need to create enough pressure to pump the blood a short distance into the ventricles

161
Q

briefly what is happening in ventricular systole

A

atria relax
ventricles contract

162
Q

describe ventricular systole

A

atria walls relax
ventricles contract and the pressure increases and soon exceeds the pressure in the aorta and PA so semilunar valves are forced open
Pressure in ventricles higher than in atria so AV valves close (LUB sound) and back flow is prevented
blood expelled from ventricles through aorta and PAs

163
Q

what happens after ventricular systole?

A

ventricular and atrial diastole
high pressure develops in both arteries and this forces blood back towards ventricles so semilunar valves close (DUB sound), preventing back flow
atria then start filling again

164
Q

what is the function of the pericardial fluid?

A

prevents friction when the heart beats

165
Q

what percentage of the heart’s muscle mass is cardiac muscle?
what is this specialised for?

A

50%
rhythmic contraction

166
Q

what are individual muscle cells called?

A

myocytes

167
Q

brief description of group of myocytes

A

branched
join together by a series of intercalated discs forming a dense network

168
Q

how are pacemaker cells connected to surrounding muscle fibres?

A

via intercalated discs

169
Q

what do pacemaker cells do?

A

co-ordinate the heartbeat and allow excitation to spread from cell to cell quickly

170
Q

do cardiac muscle cells have a long or short refactory period?
what is this?

A

long
when they are completely unable to contract

171
Q

long refactory period in cardiac muscle cells function

A

ensures that each contraction is separated by a resting period
allows the heart to refill with blood before the next contraction
prevents oxygen debt so cardiac muscles down fatigue

172
Q

how are cardiac muscle cells’ high oxygen demands met?

A

numerous capillaries
oxygenated blood in aorta flows into coronary artery, into capillaries which supply the muscle cells with oxygen (by diffusion out of capillaries)

173
Q

where does deoxygenated blood from the cardiac muscle go?

A

into cardiac veins
then drains into coronary sinus
empties into right atrium

174
Q

what happens if embryonic heart cells are separated into a Petri dish and kept alive?
what does this tell us about the origin of a heart beat?

A

each is capable of generating its own electrical impulse followed by a contraction
its not a nerve impulse, but an inherent property of cardiac muscle cells (myogenic)

175
Q

what does cardiac muscle do if a heart is surgically removes?

A

continues to contract rhythmically

176
Q

why do myocytes have many mitochondria?

A

to prevent fatigue

177
Q

intercalated discs function

A

enable synchronised contraction
gap junctions so allow quick ion movement between cells

178
Q

how many nuclei do myocytes have?

A

multiple

179
Q

heart rate definition

A

the number of times the heart beats in 1 minute

180
Q

stroke volume definition

A

the amount of blood pumped by each ventricle with each heartbeat

181
Q

average stroke volume

A

70ml per beat in an adult at rest

182
Q

cardiac output definition

A

the volume of blood ejected from the left or right ventricle into the aorta or pulmonary artery per minute

183
Q

cardiac output equation

A

heart rate x stroke volume

184
Q

cardiac output units

A

ml/minute

185
Q

factors affecting heart rate

A

autonomic innervation
hormones
fitness levels
age

186
Q

factors affecting stroke volume

A

heart size
fitness levels
gender
contractility
duration of contraction
preload (EDV)
afterload (resistance)

187
Q

what is auscultation?

A

listening to a patient’s heart sounds
valved disorders trigger abnormal heart sounds/murmurs
these can be heard with a stethoscope

188
Q

what is stenosis?

A

when heart valves become rigid
the loss of flexibility of the valve interferes with normal function and may cause the heart to work harder to propel blood through the valve, which actually weakens the heart

189
Q

why does cardiac output increase when somebody exercises?

A

increased oxygen/glucose demand due to muscle cells respiring when muscles contract
increased heart rate to pump more blood to meet demand
exercise increases venous blood return to the heart, causing increased heart rate
volume of blood in heart increases, resulting in extra stretching of left ventricular wall, meaning a stronger contraction and stroke volume increases

190
Q

effect of training on cardiac output?

A

increased cardiac output of trained person without increasing heart rate
increased ventricular wall stretching and stronger contractions causes the muscle in the left ventricle wall to increase in thickness
therefore at rest, stroke volume is higher in a trained athlete than untrained, so it takes less bpm to deliver same cardiac output

191
Q

explain change in aortic pressure during heart cycle

A

rises during ventricular systole as blood is forced into aorta
then gradually falls, but never below around 12kPa, because of the elasticity of its wall, which creates a recoil action: essential if blood is to be constantly delivered to the tissues
recoil provides temporary rise in pressure at the start of diastole

192
Q

explain change in atrial pressure during heart cycle

A

always relatively low bc the thin walls of the atrium cannot create much force
it is at its highest when the atria are contracting (atrial systole), but drops when the bicuspid valve closes and its walls relax
the atria then fill with blood, which leads to a gradual build-up of pressure until a slight drop when the bicuspid valve opens and some blood moves into the ventricles

193
Q

explain change in ventricular pressure during heart cycle

A

low at first, but gradually increases as ventricles fill with blood during atrial systole
bicuspid valves close and pressure increases dramatically as the thick muscular walls of ventricle contract
as pressure rises above that of the aorta, blood is forced into the aorta past the semi-lunar valves
pressure decreases as ventricles empty and walls relax at the start of diastole

194
Q

explain change in ventricular volume during heart cycle

A

almost the mirror image of ventricular pressure, but w/ a short time delay
volume increases during atrial systole, as ventricles fill with blood, and then drops suddenly as blood is forced out into the aorta when ventricular pressure exceeds aortic pressure
volume increases again as the ventricles fill with blood during diastole

195
Q

what is an ECG

A

a record of the wave of electrical activity caused by atrial systole (P), ventricular systole (QRS), and the start of ventricular diastole (T)

196
Q

what is angina?

A

a condition in which plaques build up and reduce the blood flow to the cardiac muscle through the coronary artery.
it results in pain during exercise

197
Q

what is a myocardial infarction

A

heart attack
takes place when atherosclerosis leads too formation of a clot that blocks the coronary artery entirely, depriving the heart muscle of oxygen so it dies
can stop the heart functioning

198
Q

what is the cardiac cycle controlled by?

A

a small patch of specialised myogenic muscle tissue in the walls of the right atrium: PACEMAKERS

199
Q

what does myogenic mean

A

initiate their own contraction

200
Q

what are the 2 nodes in the heart?

A

sinoatrial node (SAN)
atrioventricular node (AVN)

201
Q

affects of nerves and hormones on HR and how

A
  1. accelerator/sympathetic nerve acts on the SAN to increase HR
  2. vagus nerve acts on the SAN to lower HR
  3. adrenalin and noradrenalin act on the SAN to increase HR

endocrine and nervous system can change the frequency of the heart beats (waves of excitation from SAN)

202
Q

what is the SAN and what does it do?

A

acts as a pacemaker (sets rate of heart)
SAN= specialised group of cardiac fibres (cells) which initiate a wave of excitation which spreads across the walls of the atria, causing depolarisation and therefore co-ordinated simultaneous contraction

203
Q

what happens when the wave of excitation reaches the AVN? what is the AVN?

A

AVN= a second group of specialised cells near the base of the right atrium
AVN delays the conduction by about 0.13 seconds
AVN provides route for transmission of the wave of excitation from the atria to the ventricles

204
Q

what is the AVN continuous with?
what is this?

A

bundle of His
modified cardiac fibres running down the inter ventricular septum; they fan out over the wall of the ventricles forming a network of fibres called Purkyne fibres

205
Q

what happens when wave of excitation reached bundle of His

A

wave of excitation conducted by Purkyne fibres to the apex of the ventricles and then radiates upwards through the walls of the ventricles, causing depolarisation and therefore the cells contract from the apex up, forcing blood up and out of the heart

206
Q

what is the non-conductive tissue

A

between atria and ventricles
atrioventricular septum

207
Q

advantages of co-ordinating the heartbeat?

A
  1. ensures cells in the atria contract at same frequency & in synchrony
    2.ensures ventricular systole is delayed before both ventricles contract in synchrony so that we have maximum pumping effect
208
Q

how does an ECG work?

A

a pair of surface electrodes are placed directly on the heart, and record a repeating pattern of potential changes.
as impulses spread from the atria to the ventricles, the voltage measured between the 2 electrodes varies
this provides a ‘picture of electrical activity of the heart

209
Q

how come an ECG works on humans?

A

the body is a good conductor of electricity
thereof the potential differences generated by the heart are conducted to the body surface where they can be recorded by the surface electrodes placed on the skin

210
Q

what is the P wave?

A

electrical activity during atrial systole depolarisation

211
Q

what is the QRS wave?

A

electrical activity during ventricular systole depolarisation
atria also repolarise during this period, but the event is hidden by the greater depolarisation in the ventricles

212
Q

what is the T wave?

A

ventricular repolarisation (recovery of ventricular wall)

213
Q

what is the Q-T interval?

A

contraction time (ventricles contraction)

214
Q

what is the T-P interval?

A

filling time: ventricles relaxed and filling with blood

215
Q

when the SAN sends out its wave of excitation, why does this not go all the way down into the ventricles?
what would happen if the atria and ventricles all contracted at the same time?

A

due to non-conductive tissue between the atria and ventricles (atrioventricular septum) through which the impulse cannot conduct
ventricles and atria would contract at the same time/ventricular systole wouldn’t be delayed, so wouldn’t be filled with blood, meaning they do not have the maximum pumping effect, so there is a lack of blood flow to the lungs and body

216
Q

step by step heart conduction

A

SAN (at top of RA) generates electrical activity
wave of excitation passes over both atria, causing cardiac muscle cells to contract. atrial systole initiated
atrioventricular septum prevents conduction of impulse to ventricles
AVN (at top of septum)= only route for impulse to take. its delayed in the node, giving time for atria to finish systole
impulse carried down Purkyne tissue down to base of interventricular septum, spreads out over walls of ventricles and upwards, causing muscle to contract, pushing blood out of arteries at top of heart

217
Q

what is bradycardia?

A

slow herat rate
resting heart rate less than 60bpm

218
Q

bradycardia
ECG trace
causes?
symptoms

A

pattern of electrical activity is normal but slow
could indicate good aerobic fitness (elite athlete), drug use (tranquillisers, beta blockers; overdose of non-prescription or prescription)
causes may need investigation due to risk of blood clots
fatigue, dizziness, low blood pressure

219
Q

what is tachycardia?

A

rapid heart rate
reskin heart rate greater than 100bpm

220
Q

tachycardia
causes
symptoms
treatment

A

exercise, excitement, stress, drugs (e.g. caffeine, nicotine, amphetamine)
sometimes HR is so high that little blood is actually pumped bc filling time is so short, leading to a lower CO
symptoms include palpitations, shortness of breath and fainting
treatment may involve relaxation therapy, beta blockers

221
Q

what is atrial fibrillation?

A

abnormal rhythm of the heart
heartbeat is irregular as has lost its rhythm
atria contracting more frequently than ventricles
no clear P wave

222
Q

atrial fibrillation
symptoms
describe
causes?
risks

A

rapid impulses generated by atria (so contract fast-fibrillate)
heart doesn’t pump blood effectively, as heartbeat is unco-ordinated
waves are initiated by atrial cells so disorganised
could be caused by scar tissue from a previous heart attack
risk of blood clots and strokes

223
Q

what is ventricular fibrillation?

A

electrical impulses firing from multiple points in ventricles
rhythm of heartbeat is lost
no clear P,QRS or T waves
unco-ordinated contraction, so there is fluttering and little blood is pumped
IRREGULAR
(usually contraction of cardiac muscles is coordinated)

224
Q

solution for ventricular fibrillation?
cause of ventricular fibrillation

A

defibrillation: heart is shocked so stops, when it restarts, it may do so with a normal rhythm
caused by lack of O2 to heart e.g. due to CHD, causes blood clot so blood flow is prevented

225
Q

what is an ectopic heartbeat?

A

heart bets too early follows by a longer-than-normal gap until next heartbeat
extra heart beats that are out of normal rhythm

226
Q

how often do people have ectopic heartbeats?

A

usually 1 per day

227
Q

what does a large PR interval suggest?

A

indicates slow conduction between atria and ventricles
could be slow conduction by AVN/ in delay at AVN or slow atrial conduction

228
Q

what part of the heart is enlarged in a person with pulmonary hypertension, giving a large P wave

A

right atrium
right side of heart has to work harder to pump blood through the pulmonary arteries

229
Q

what are the 5 types of blood vessel?

A

artery
arteriole
capillary
venule
vein

230
Q

artery diameter

A

up to 3cm (aorta)

231
Q

arteriole diameter

A

less than 100 um

232
Q

capillary diameter

A

average 8um

233
Q

venule diameter

A

20-30um

234
Q

vein diameter

A

up to 2.5 cm (inferior vena cava)

235
Q

artery components

A

tunica adventitia
tunica media (v thick)
tunica intima
lumen

236
Q

artery wall thickness and why

A

thick
maintain and withstand high pressure

237
Q

what is tunica adventitia in arteries made from

A

collagen (fibrous protein), provides strength to withstand high pressure
elastic fibres (made from fibrous protein elastin), stretch to prevent bursting and recoil to propel blood and even out surges in blood pressure

238
Q

what is tunica media in arteries made from?

A

elastic lamellae (made from fibrous protein elastin) which stretch to prevent bursting and recoil to propel blood and even out surges in blood pressure
muscle (smooth muscle), maintains blood pressure

239
Q

what is tunica intima in arteries made from?

A

endothelium (impermeable), smooth lining to decrease friction so increase blood flow, folded or corrugated so can expand when artery stretches
connective tissue

240
Q

artery lumen size and why

A

narrow
small relative to diameter of artery
smaller comparable to veins
maintains blood pressure

241
Q

what makes up a capillary

A

endothelial cells
basement membrane
pores in capillary wall
pinocytic vesicles

242
Q

basement membrane in a capillary wall description

A

filter
prevents proteins and erythrocytes leaking out

243
Q

endothelial cells in capillary wall description

A

1 cell thick
decreases diffusion distant for oxygen

244
Q

pores in capillary wall description

A

fenestrations allow tissue fluid formation

245
Q

what makes up an arteriole

A

tunica adventitia
tunica media
tunica intima
lumen

246
Q

arteriole tunica media makeup compared to arteries

A

less elastic tissue
more smooth muscle
bc lower pressure

247
Q

what is the diameter of an arteriole controlled by?

A

muscle layer

248
Q

what is a venule made from?

A

tunica adventitia
tunica media (may be absent)
tunica intima
lumen

249
Q

venule lumen diameter control?

A

not precisely controlled

250
Q

what makes up a vein

A

tunica adventitia
tunica media
tunica intima
lumen
valves to prevent backflow of blood

251
Q

tunica adventitia in veins description

A

thick layer of collagen and elastic fibres
provides strength

252
Q

tunica media in veins description

A

poorly developed
less smooth muscle and elastic fibres in the wall

253
Q

tunica intima veins description

A

endothelium with little connective tissue
sometimes indistinct from tunica media under a microscope

254
Q

vein lumen diameter and why

A

large (larger comparable to arteries)
can accommodate large volumes of blood
eases blood flow back to heart because a smaller percentage of blood is in contact with the walls so there is less resistance to flow

255
Q

vein wall thickness and why

A

thinner wall
doesn’t need to withstand a high blood pressure

256
Q

blood flow is what speeds during systole and diastole?
why?

A

blood is expelled from the heart only when it contracts, therefore bloodflow through the arteries is intermittent
rapid during systole
slow during diastole

257
Q

blood flow in capillaries? why?

A

flowing evenly
due to elastic recoil of the artery walls

258
Q

what is a pulse?

A

expansion of the artery as ventricular systole forces waves of blood in, a pulse is felt especially in arteries close to the skin surface

259
Q

where is blood flowing the fastest?

A

in arteries

260
Q

where is blood flowing the slowest?

A

capillaries

261
Q

what is the velocity of blood flow inversely proportional to?

A

cross sectional area of the blood vessel

262
Q

why does blood flow slowly through the capillaries?

A

there is adequate time for the exchange of materials between the capillaries and the adjacent tissues

263
Q

how is blood flow in capillaries increased?

A

localised increases in metabolites e.g. CO2 and H+ and a decrease in O2 cause vasodilation, increasing blood flow to the capillary bed

264
Q

how is blood flow in capillaries reduced?

A

there are pre-capillary sphincter muscles (smooth muscles)
when these contract they cause construction, which either prevents or reduces the flow of blood to a capillary network
blood can then bypass the capillary bed

265
Q

what is another name for a bypass vessel?

A

shunt vessel

266
Q

how is blood flow in veins maintained?

A

pumping action of the heart
contractions of skeletal muscle during normal movements squeezes on the thin walled veins
this increases the pressure of the blood inside
valves ensure that this pressure directs blood back to the heart. veins run close to/within muscles/
inspiratory movements reduces pressure in the thorax, helping to create a pressure gradient to draw blood towards the heart which is in the thorax. expiratory pressure changes means pressure increases in veins outside the heart, speeding blood flow in to the heart

267
Q

describe and explain how the structure of the arteries and veins links to their functions: ARTERIES

A

ARTERY function= transport blood away from the heart under high pressure
thick walls with collagen= strength to withstand high pressure
lots of elastic fibres can stretch and recoil= convert pulses to smooth flow
smooth muscle can contract= constricts the lumen to maintain blood pressure and flow
folded epithelium= prevents damage as the artery wall stretched in due to systolic pressure

268
Q

describe and explain how the structure of the arteries and veins links to their functions: VEINS

A

VEIN function= transport blood back to the hart under low pressure
thinner walls, much less smooth muscle and elastic tissue= flow may be increased due to skeletal muscle contraction which squeezes on veins
larger lumen= less resistance to flow and smaller % of blood in contact with walls
has valves, helps to prevent back flow as blood is under low pressure

269
Q

components of blood?

A

erythrocytes
plasma
platelets
leukocytes

270
Q

what are leukocytes

A

phagocytes
neutrophils
lymphocytes (T and B)

271
Q

what are platelets

A

fragments of dead cells
involved in blood clotting

272
Q

what’s plasma made up of?

A

it is a straw-coloured liquid
90% water
plasma proteins
carries cells, nutrients (to where they are required) and waste
carries ions (HCO3-, Na+,Cl-), hormones. urea, CO2, heat (thermoreg.), antibodies (glycoproteins), glucose, amino acids, lipid proteins (e.g. cholesterol)

273
Q

plasma proteins examples

A

albumen carries steroid hormones
fibrinogen involved in blood clotting

274
Q

erythrocytes lifespan and why

A

3 months
due to damage
survive on anaerobic respiration

275
Q

where are erythrocytes broken down?

A

in the liver
used to make bile

276
Q

hydrostatic pressure definition
positive or negative

A

blood pressure inside the capillaries/arteries cause by fluid pushing against the sides of the vessel
heart=pump (cause)
POSITIVE

277
Q

oncotic pressure definition
positive or negative

A

the net pressure that drives reabsorption: the movement of a fluid from the tissue fluid back into the capillaries.
due to the presence of plasma proteins (solute decreasing water potential) in the blood and the absence of these in the tissue fluid
negative

278
Q

what is the net filtration pressure (NFP)

A

represents the interaction of the HP and OP, driving fluid out of the capillary
it is equal to the difference between the HP and the OP
negative when net reabsorption into capillaries is occurring
positive when net filtration out of capillaries is occurring

279
Q

what percentage of tissue fluid drains into lymphatic vessels?

A

10%

280
Q

why does some excess tissue fluid drain into lymphatic vessels?

A

prevents buildup/accumulation
drain goes back into blood supply

281
Q

tissue fluid function

A

exchange between cells and tissue fluid takes apace
bathes cells, providing them with glucose and amino acids
cells release waste products and tF carries these away

282
Q

describe tissue fluid formation

A

TF formation occurs at arterial end of capillary bed
there is a high HP at this end
net HP>net OP
fluid is forced out via fenestrations
water glucose and solutes to tissue cells
this is pressure filtration
red blood cells and large plasma proteins remain in the blood vessels as they cannot pass through the basement membrane

283
Q

describe tissue fluid reabsorption

A

TF reabsorption occurs at venous end of capillary bed
net HP<net OP
OP has not changed between arterial end and venous end as plasma proteins remain in blood
HP in venous end has reduced because fluid was lost from the blood
fluid and waste products/ solutes e.g. salt are reabsorbed by osmosis
about 10% of the fluid drains into lymphatic vessels and can eventually join back with normal circulation 8

284
Q

suggest why it is important that capillary walls are impermeable to albumen, the most abundant plasma protein

A

must stay in blood where it raises solute concentration, keeping OP high
draw water in with tissue fluid
if it diffused out, OP decreases so more water accumulates -> oedema

285
Q

what is oedema

A

swelling in a tissue caused by accumulation of tissue fluid
net filtration pressure is higher/ oncotic pressure is lower in capillary

286
Q

reasons for oedema

A

heart disease causes high BP, raising HP, so higher NFP, so more fluid accumulates
Kwashiorkor’s= lack of protein in diet= less plasma proteins in capillary= lower OP in capillary= higher NFP = more fluid accumulates/forms and less reabsorbed due to lower OP
kidney disease= lose proteins in urine = as above

287
Q

what is the lymphatic system?
how is it arranged?

A

a system of vessels that drain excess fluid away from the tissues
blind ending lymphatic capillaries are found draining all the tissues
the end of the lymph capillaries have tiny valves which allow fluid to flow in but not out
the blind ending lymph capillaries join to form larger lymphatic vessels, which join up with the circulatory system at the subclavian vein in the neck

288
Q

lymph composition

A

lymph is a colourless/pale yellow fluid similar to tissue fluid (minus the proteins)
composition depends on the tissue:
in liver it contains proteins as they are made by the liver
in small intestine more lipids as these are absorbed here via villi of ileum

289
Q

what causes the movement of the lymph

A

skeletal muscle contraction
respiratory pump
hydrostatic pressure
valves
smooth muscle in lymphatic vessels

290
Q

functions of the lymph

A

returns 10% of tissue fluid back to the blood
returns plasma proteins to blood (made by liver)
lacteals allow FA and glycerol to enter blood
help to prevent pathogens entering circulation

291
Q

name 2 blood components that move out of the capillaries

A

water form plasma
neutrophils

292
Q

name 2 components of the blood that do not move out through the capillary walls

A

large plasma proteins
erythrocytes

293
Q

name 4 transported substances that would move out of the blood into the tissues

A

glucose
amino acids
salts/hormones
mineral ions

294
Q

how is hydrostatic pressure generated

A

pumping action of the heart

295
Q

state a major component of plasma that contributes to the osmotic pressure (solute potential)

A

plasma proteins

296
Q

explain the importance of lymphatic drainage

A

returns 10% of tissue fluid back to blood via lymph
helps to prevent pathogens entering circulation
returns plasma proteins to the blood
more fluid is lost than reabsorbed by capillaries
prevents oedema/swelling/fluid retention

297
Q

constituents of blood

A

plasma
RBC
WBC
platelets

298
Q

constituents of tissue fluid

A

like plasma but without large proteins
WBC may squeeze out into TF

299
Q

constituents of lymph

A

like tissue fluid but with more fat, WBC and antibodies

300
Q

explanation of differences in constituents of blood, TF and lymph

A

most proteins are too large to cross capillary wall
WBC can squeeze through pores in capillary walls

301
Q

formation of blood

A

stem cells in bone marrow

302
Q

formation of tissue fluid

A

filtration pressure across capillary wall

303
Q

formation of lymph

A

excess tissue fluid drains into the lymph

304
Q

where is blood found

A

heart
blood vessels

305
Q

where is tissue fluid found

A

bathing cells

306
Q

where is lymph found

A

in lymph vessels and passes through the lymph nodes

307
Q

function of blood

A

transport of substances and defence against disease

308
Q

function of tissue fluid

A

transport over short distances and exchange of material within cells

309
Q

function of lymph

A

returns excess fluid to the blood via the subclavian vein
defence

310
Q

pressure of blood

A

high

311
Q

pressure of tissue fluid

A

low

312
Q

pressure of lymph

A

low

313
Q

partial pressure of gases definition

A

pressure exerted by a gas in a mixture of gases
is directly related to the concentration of that gas in the mixture

314
Q

normal atmospheric pressure

A

760mm Hg (sum of all major gases in the air)

315
Q

% of oxygen in the air

A

21% or 20.95%

316
Q

partial pressure of oxygen in air

A

21% of 760
160mm Hg

317
Q

why is pO2 high in the pulmonary vein and systemic arteries?

A

higher conc. of O2 because O2 has been inhaled and associated with haemoglobin

318
Q

pO2 in atmosphere, alveolar air, pulmonary veins and pulmonary arteries in mm Hg

A

atmosphere=160
alveolar air= 104
PV= 104
PA= 40

319
Q

what does the oxygen dissociation curve look like

A

slow increase
steep increase
levels out

320
Q

why is there a slow increase at the start of the oxygen dissociation curve?

A

haem groups are found in the middle of the haemoglobin, so it is difficult for the firs oxygen to associate

321
Q

why is there a steep increase in the middle of the oxygen dissociation curve?

A

once the first oxygen molecule associates there is a slight change in the shape of the haemoglobin- this makes it easier for more oxygen to diffuse in and associate with Hb
CONFORMATIONAL CHANGE

322
Q

why does the oxygen dissociation curve level out at the end?

A

once the haemoglobin contains 3 oxygen molecules it becomes harder for the 4th to associate: despite the partial pressure being high it is difficult to get 100% saturation

323
Q

relationship between partial pressure of oxygen and affinity w/ haemoglobin

A

when pO2 is low e.f in respiring tissues 2kPa, Hb has a low affinity for O2 so it unloads O2 and so it has a low saturation of O2 around 20%
where pO2 is high e.g. in lungs 12kPa, Hb has a high affinity for O2, so it has a high saturation of 95% and is loading O2

324
Q

why is oxygen dissociation curve ‘s’ shaped/sigmoid

A

as one molecule of O2 binds to haemoglobin, the affinity of oxygen increases due to conformational change in the shape of Hb

325
Q

difference between foetal and adult Hb oxygen dissociation curve graphs?
why?

A

foetal Hb curve is shifted to the left
at each point along the curve, foetal haemoglobin has a higher affinity for oxygen so therefore a higher oxygen saturation
this means that it can always load oxygen from the maternal haemoglobin in the placenta through the villi
e.g. at low pO2, adult Hb has lower % sat of oxygen so has unloaded O2 but foetal Hb has higher % sat so has loaded O2

326
Q

difference between the myoglobin and haemoglobin oxygen dissociation curves?
why?

A

myoglobin curve is shifted to the left
myoglobin has a very high affinity for O2: this means that it will only dissociate & unload oxygen when oxygen levels are very low
in normally respiring tissues myoglobin still has a high saturation with oxygen
e.g. at low pO2, myoglobin has a high % sat, so will load O2. when pO2 is les than 1kPa, will unload

327
Q

what is myoglobin important for?

A

important for habitats where oxygen concentrations are low e.g. high altitudes and deep water of lake/ocean

328
Q

in which ways is CO2 transported away form respiring tissues?

A

about 5% dissolves directly in the blood plasma
about 85% is transported in the form of hydrogen carbonate ions in the blood plasma
a further 10% is combined directly with haemoglobin to form carbaminohaemoglobin

329
Q

where doesCO2 bind to Hb

A

binds to amino acid residue on the globin portions(in polypeptide chain) (not competitively with O2)

330
Q

what is carboxyhaemoglobin
dangerous?

A

carbon monoxide binds to Hb competitively against O2
irreversible, prevents O2 transport
higher affinity than O2

331
Q

what is haemoglobinic acid?
uses?

A

HHb
H+ ions bind to Hb so Hb is a buffer and mops up H+, limiting a decrease in blood pH
when H+ bind to Hb, they change the shape of Hb (conformational), which reduces Hb affinity for O2 and makes it unload O2 more readily, so there is more dissociation of O2 from oxyhaemoglobin at respiring tissues where H+ conc is high

332
Q

step by step how CO2 affects blood pH and how this leads to oxygen unloading

A
  1. CO2 diffuses into RBC down pCO2 gradient
  2. CO2 reacts with H2O, catalysed by carbonic anhydrase, to form carbonic acid
  3. acid dissociates into H+ and HCO3- ion
  4. HCO3- diffuses into blood plasma
  5. Cl- diffuse into RBC to maintain electrical balance= chloride shift
  6. H+ bind to Hb, forming haemoglobinic acid, which reduces its affinity for O2, so O2 unloads
  7. O2 dissociates to from oxyhaemoglobin
    8.O2 diffuses out of RBC to respiring cells
333
Q

what does carbonic anhydrase enzyme require to catalyse reaction?

A

requires cofactor (prosthetic group)
Zn2+ ion

334
Q

where does the reverse of the CO2 oxygen unloading process happens?

A

in the lungs

335
Q

what is the Bohr effect

A

the presence of carbon dioxide helps the release of oxygen from haemoglobin.

336
Q

what is the Bohr shift
how can this be seen?

A

when more carbon dioxide is present the curve for oxygen dissociation shifts to the right
compare the oxygen dissociation curves where there is less carbon dioxide present and when there is more carbon dioxide in the blood

337
Q

Bohr shift graph conclusions

A

the higher the pCO2, the more readily Hb unloads O2 to cells
this allows more O2 to be given to cells which have a high activity e.g. respiring tissues with low pO2 and high pCO2
e.g. at a certain pO2, the Hb % sat is lower when there is more w/ CO2 present in the blood. therefore if more CO2 present, Hb has a reduced affinity for O2
as pCO2 increases, the O2 dissociation curve shifts right

338
Q

when is a haemoglobin said to be saturated and partially saturated?

A

partially saturated= when 1 to 3 ham sites re occupied
saturated=when all 4 hame sites are occupied

339
Q

what does a haemoglobin saturation of 100% mean?

A

every harm group in all of the erythrocytes of the body is bound to oxygen

340
Q

what is general haemoglobin saturation in a healthy individual with normal Hb levels?

A

95 to 99 %

341
Q

example of a tissue with low metabolic rate

A

adipose
(body fat)

342
Q

difference between foetal Hb and maternal Hb

A

both have 4 subunits
2 of the subunits of foetal Hb have a different structure that causes foetal Hb to have a greater affinity for O2 than adult Hb

343
Q

partial pressure of oxygen in placenta, foetal blood and maternal blood?

A

lower in placenta than in maternal arteries
not large difference between foetal and maternal

344
Q

what does a lower, more acidic pH promote?
therefore what does a higher, more basic pH inhibit?

A

oxygen dissociation from haemoglobin

345
Q

effect of more CO2 in blood on pH?

A

more molecules need to be converted do more H+ ions, lowering blood pH
blood pH may become more acidic when certain byproducts of cell metabolism e.g. lactic acid, carbonic acid and CO2 are released into the bloodstream

346
Q

tone of Hb when not transporting O2?
therefore what is the colour of deoxy blood?

A

bluish-purple
dark maroon

347
Q

what is acclimatisation?
effect of low pO2 on blood

A

the process of adjustment that the respiratory system makes due to chronic exposure to high altitude
over a period of time, the body adjusts to accommodate the lower partial pressure of oxygen
the low pO2 at high altitudes results in a lower oxygen saturation level of Hb in the blood
in turn, the tissue levels of oxygen are also lower

348
Q

effect of low oxygen saturation levels on kidneys and thereforre the blood?

A

kidneys are stimulated to produce the hormone erythropoietin (EPO), which stimulates the production of erythrocytes, resulting in a greater number of circulating erythrocytes in an individual at a high altitude over a longer period
with more RBCs, there is more Hb to help transport the available O2
even though there is low saturation of each Hb molecule,, there will be more Hb present, so more O2 in blood

349
Q

adaptation of some animals at high altitude?

A

some have evolved Hb that has a higher affinity for oxygen than normal adult Hb in humans
this means their Hb is able to associate with oxygen more readily at lower partial pressures

350
Q

where can a pulse be felt

A

arteries

351
Q

sphincter muscles are typically found in the walls of which vessels?

A

arterioles

352
Q

why does diastole follow systole?

A

cardiac muscle takes a short time to repolarise after being stimulated

biology (28 decks)

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