module 3 Flashcards
(238 cards)
1
Q
what is the need for specialised exchange surfaces
A
it is enough for diffusion to supply oxygen and remove co2 as the metabolic activity of a single celled organism is usually low, so oxygen demands and co2 production is low, and the sa:v ratio is large eg metabolic activity is higher in larger organelles than single celled ones as the amount of energy used in moving means oxygen demands are high as they produce a large amount of co2, the distance is too far for effective diffusion
2
Q
what are the 4 features of a specialsied exchange surface
A
increased sa- area needed for exchange and overcomes sa:v ratio eg root hair cells and villi
thin layers-short diffusion pathway, fast and efficient process, alveoli and villi
good blood supply-steeper conc gradient, faster diffusion, subtances are constantly delivered, and removed, alveoli, gills and villi
ventilation to maintain diffusion gradient-more efficient process, flow of water carrying dissolved gases- alveoli and gills
3
Q
what are the 3 uses of exchange surfaces
A
-exchange of respiratory gases eg oxygen
-absorption of nutrients
-removal of excretory products
4
Q
factors affecting exchange surfaces
A
size, level of activity and sa:v ratio
5
Q
heterotrophic v autotrophic
A
heterotrophic-obtain food from environment whereas autotrophic accquire nutrients differently eg plants and photosynthesis
6
Q
what is the need for the mammalian gaseous exchange system
A
increase metabolic rate as they are active and maintain body temperature independent from environment, o2 needed for cellular respiration and production of co2 which needs to be removed-done by the lungs
7
Q
what are the 5 features of the gaseous exchange system
A
nasal cavity, trachea, bronchus, bronchioles and alveoli
8
Q
what are the features of the alveoli
A
tiny air sacs for main gaseous exchange, 200-300um diameter, flattened epithelial, collagen and elastic fibres, allow to stretch with air, then squeeze at resting size (elastic recoil)
9
Q
nasal cavity features
A
large sa and good blood supply, warms air to body temp, hairy lining, traps dust through mucus to prevent it reaching lungs, moist surface, increase humidity and decrease evaporation, then enters lungs
10
Q
trachea features
A
main airway, incomplete rings of strong flexible cartilage to stop trachea from collapsing, food can move down oseophagus easily behind, lined with ciliated epithelium and goblet cells, secrete mucus, beat and move mucus, with trapped dirt and microorganisms
11
Q
bronchus features
A
in chest cavity, divides into left and right according to each lung, similar structure to trachea but incomplete rings of cartilage are smaller
12
Q
bronchioles features
A
divide into many smalll bronchioles, no cartilage rings as they are less than 1mm in diameter, smooth muscle walls, contract=bronchioles constrict, relax=bronchioles dilate, changes air reaching lungs , lined with flattened epithelium for more gaseous exchange
13
Q
what are the three reasons for transport in plants
A
1.metabolic demands-produce glucose and oxygen from photosynthesis, needs to be transported around plant and waste products need to be removed, mineral ions absorbed by roots needed in all cells for proteins and hormones also need to be transported
2.size-small but continue to grow or perennial plants are large so effective transport systems are needed to move substances up and down
3.sa:v ratio-eg leaves are adapted to increased sa:v ratio for gaseous exchange but size, complexity of multicellular plants means stems and trunks have a small one and cannot rely on diffusion alone
14
Q
different plant transport systems
A
dictotyledonous=make seeds that contain two organism that act as food stores for developing a plant
which further differentiates into herabacous which is a short life cycle and arborscent which have a long life cycle
all have a vascular system arranged in vascular bundles (leaves, roots and stems)
-young herbacous stem which provides strength and support
-young herbacous root which helps withstand tugging strain from wind
-dicot leaf which support structure of the leaf and transport
15
Q
6 features of the alveoli
A
large surface area, very thin walls, moist, partially permeable surface, narrow capillaries, good blood supply
16
Q
why is a large surface area needed for alveoli
A
large no of alveoli although they are small, large additional area for gaseous exchange
17
Q
why is very thin walls needed for alveoli
A
alveolur and capillary wall are one cell thick and have flat and thin squamous epithelium, capillaries are in close contact and narrow, creating a short diffusion pathway
18
Q
why is a narrow capillaries needed for alveoli
A
only one blood cell can pass at a time, rbc must squeeze through, reduces rate of flow, so gas exchange can occur
19
Q
why is moisture needed for alveoli
A
dissolves gas and substances, prevents alveoli from collapsing, o2 and co2 are easily exchanged, maintains surface area for gas exchange
20
Q
why is a good blood supply needed for alveoli
A
surrounded by network of capillaries, constant movement of oxygen taken away and co2 being brought in, ventilation takes place, maintains steep concentration gradient
21
Q
why is a partially permeable surface needed for alveoli
A
allows small, soluble molecules to cross easily, so gas exchange can occur
22
Q
why are transport systems needed for multicellular plants
A
-metabolic demands-many internal parts do not photosynthesise so hormones, minerals, waste all need to be transported through the plant
-size=perennials are enornmous, need to move up and down, from root tip to top most leaves and stems
-sa:v ratio=complex, small sa:v ratio, diffusion alone will not suffice
23
Q
monocot v dicot
A
monocot=seeds make one cotlyedon
dicot=seeds make two
cotyledon=organ that acts as a food stopre for developing embryo plant
24
Q
what is ventilation
A
mass movement of air in and out the lungs, due to pressure changes in the thorax/chest cavity, due to breathing movement
25
how does ventilation occur
rib cage provides semi rigid case, pressure can be lowered with respect to atmospheric air pressure outside it, diaprhagm is a braod cloned sheet of muscle, forms the flooor of the thorax, external and internal intercostal muscles found between the ribs, lined with pleural cavity, filled with a thin layer of lubricating fluid membranes, slide easily while breathing
26
what happens in inhalation
energy using process, diaphragm contracts and lowers, external intercostal muscles contract and moves ribs out and up, volume of thorax increases, pressure in thorax increases, lower than atmospheric pressure, air is drawn through nasal passage, trachea, bronchi, bronchioles into lungs, equalises pressure inside and outside chest
27
what happens in exhalation
passive process, msucle of diaphragm relaxes, moves up into resting dome shape, external intercostal muscles relax, ribs move down and inwards, under gravity, elastic fibres in alveoli of lungs return to normal length, decreases volume of thorax and pressure inside thorax is higher than pressure of atmospheric air, air moves out until pressure is equal, can be done foricbly by using energy to push internal intercostal muscles contract, pulls ribs down hard and fast, abdominal muscles contract and force diaphragfm up due to pressure
28
what is the xylem and its function
non living tissue, transports water and mineral ions, provide support, up from roots to shoots and leaves, one direction, long and hollow, several columns, thick walled, contains tannin deposits which is a bitter tasting chemical which protects the plant from herbivores, xylem fibres are long cells with lignified secondary walls, provide extra mechanical strength, do not transport water, lignin can form spirals and rings , solid tubes border xylem
29
what is the phloem and its function
living tissue, transport food imn the form of organic solutes made by photosynthesis, supplies cells with amino acids and sugars eg sucrose for cellular respiration, synthesis of useful molecules, up and down plant, sieve tube elements, long and hollow, not lignified, large pores appear in the cell walls, tonoplast, nucleus, filled with phloem sap and mature phloems have no nuclei, closely linked to companion cells by plasmosmata, microscopic channels through cytoplasm of adjacent cells, very active, life support system, fibres and sclereids(thick cell walled)
30
what is the function of the ciliated epithelial cell in the mammalian gas exchange system
cells line from the trachea to the mouth, have hair like projections called cilia, sweep mucus, dust, bacteria and microorganisms up and away from the lungs and mouth, swallowed and digested by stomach acids
31
what is the function of the goblet cell in the mammalian gas exchange system
embedded throughout the ciliate deipthelium, mucus producing cells, traps dust, bacterian and microorganisms,
32
what is the function of the mucous glands in the mammalian gas exchange system
work with goblet cells in trachea and bronchi to produce mucus
33
what is the function of the cartilage in the mammalian gas exchange system
rings of cartilage and spirals line the trachea, strong and flexible tissue keeps trahcea open, move and flex as we breathe
34
what is the function of the smooth muscle in the mammalian gas exchange system
msucle not under conscious control, found in walls of bronchi and bronchioles, regulates flow of air in and out of lungs by dilating and widening,
35
what is the function of the elastic fibres in the mammalian gas exchange system
found in squamous epithelium of alveolar walls, allow tiny alveoli to stretch, fill with air and recoil to force it out, large sa due to elastic abilities
36
what is the function of the squamous epithelium in the mammalian gas exchange system
flat and thin cells in walls of alveoli, so that o2 and co2 have a short diffusion pathway
37
what tissue does the trachea contain
cartilage, smooth muscle, elastic fibres, goblet cells, ciliated epithelium, and squamous epithelium
38
what tissue does the bronchi contain
cartilage, smooth muscle, elastic fibres, goblet cells, ciliated epithelium, and squamous epithelium
39
what tissue does the small bronchioles contain
some/no cartilage, smooth muscle, elastic fibres, goblet cells, ciliated epithelium, and squamous epithelium
40
what tissue do the large bronchioles have
elastic fibres and squamous epithelium
41
what tissue does the alveoli contain
squamous epithelium, elastic fibres
42
what are the 5 characteristics of movement of water in plants
-turgor/ hydrostatic pressure due to osmosis-rprovides skeleton
-cell exapansion
-loss of water by evaporation to keep cool
-mineral ions and products of photosynthesis are transported in aqueous solutions
-raw materials of photosynthesis
43
what happens in the movement of water into the root
happens through the root hair cells, have long and thin extensions called root hairs and a specialised epidermal cell near the growing root tip, it has a large sa;v ratio with a thin large short diffusion, the concentration of solutes maintains the water potential gradient, soil water decrease in concentration of dissolved minerals
44
what are the two pathways for the movement of water across the root
symplast pathway-through cytoplasm
apoplast pathway-through cell walls
45
apoplast pathway
movement of water through cell walls and intercellular spaces, move into xylem, more water molecules pullled due to water cohesive forces creates tension, continous flow of water through cellulose wall
46
symplast pathway
cytoplasm connected through the plasmodesmata by osmosis, increase water potential- more from root hair cell to adjacent root hair cells via osmosis until xylem is reached, water potential decreases, maintains steep net water potential
47
movement of water through the xylem
water moves across root in apoplast and symplast until it reaches the endodermis, casparian strip (waxy cuticle thats runs around endodermal cells, waterproof), wanter cannot go further in the apoplast so it forces into the cytoplasm and in the symplast, needs to pass through selectively permeable cell surface membrane, solute conc in cytoplasm of endodermal cells are dilute compared to xylem, more mineral ions into xylem by active transport, water potential of xylem is less than endodermal and that increases the rate of water moving into the xylem by osmosis, once insdie the vascular bundle, water moves to apoplast to xylem and root pressure increases
48
what is transpiration
loss of water vapour from leaves and stems of plant, due to gaseous exchange
49
why does transpiration occur
leaves have large sa for capturing sunlight for photosynthesis, waxy cuticle is waterproof to prevent water loss, gases move in and out as co2 moves in from air and o2 moves out via diffusion, down conc gradient, through stomata which opens and closes according to sunlight and other conditions, to prevent water loss, however in some conditions oxygen is needed for cellular respiration so some are always open
50
how is the transpiration stream formed
water enters root by osmosis and is trnasported up until it reaches the leaves
-it then moves by osmosis across membranes, diffusion in, water moves through apoplast from xylem and evaporates from the freely permeable cellulose cell wall of mesophyll cells in leaves into airspace, water moves into external air through stomata along diffusion gradient
-it is passive and moves down the concentration gradient, water molecules evaporate from mesophyll cell into air space of leaf and out stomata by diffusion
-loss of water by evaporation from mesophyll cell lowers water potential, water moves into cell adjacent by osmosis
-repeats until it moves from leaf to xylem and moves out by osmosis in to leaf cells
- water molecules form hydrogen bonds with carbohydrates in the walls of the xylem vessel, choesion and adhesion occurs and it exhibits capillary action against force of gravity so water is drawn up continuous stream to replace water loss by evaporation=transpiration pull
-this causes tension in xylem, more water across the roots, cohesion and tension theory
51
Evidence of transpiration stream
-changes in diameter of tress, transpiration happens most in the day, tension in xylem vessels increases, therefore tree shrinks in diameter and vice versa
-xylem vessel is broken air is drawn in rather than water leaking out
-xylem vessel is broken and air is pulled in plant can no longer move water up the stem as continuous stream of water molecules held cohesive forces broken
52
5 factors affecting transpiration
light-required for photosynthesis and stomata opens for gas exchange, dark causes the stomata to close, but increase rate of water vapour diffusing out, increase evaporation and rate of transpiration
humidity-increase humidity, decrease rate of transpiration, due to reduced water vapour potential gradient between inside the leaf and outside air and vice versa
temperature-increase= increase ke, increase rate of evaporation external air can hold, decrease water potential and humidity
air movement-each leaf has a layer of still air around it trapped by leaf sap, it has hairs, leaf decreases air movement close to leaf, water vapour diffuses out leaf accumulates there, water potential around stomata increases, decreases diffusion gradient, increase rate of transpiration
soil water availability-amount of water available in soil affect transpiration rate as if very dry-underwater stress and rate of transpiration decreases
53
3
ways to measure lungs
peak flow meter- simple device that measures rate that air can be expelled from the lungs
vitalograph- sophicated version of peak flow meter, breath out quickly through a mouthpiece and produces a graph, forced expiratory volume
spirometer-measure different aspects of lung volume, investigate breathing patterns
54
breathing rhythm factors
breathing rate-number of breaths taken per minute
ventilation rate= total volume of air inhaled in one minute
ventilation rate= tidal volume x breathing rate
oxygen demands increase, breathing rate increase so the ventilation of lungs and oxygen uptake, during gaseous exchange can meet demands
55
components of measuring lungs
-tidal volume=volume of air moving out and in the lungs in each resting breath
-vital capacity=volume of air that can be breathed in with strongest exhalation and intake
-inspiratory reserve volume= maximum volume of air you can breath in inhalation
-expiratory reserve volume= extra amount of air you can breath over the normal tidal volume of air
-residual volume= volume of air left in lungs after exhaled as hard as possible
-total lung capacity= sum of vital capacity and residual volume
56
spirometer function
breath in an four through it co2 is absorbed by soda lime to stop co2 concentration in rebreathed being to high, respiratory distress- trace is drawn, or graph is formed digitally, vital capacity, tidal volume and breathing rate calculated, oxygen uptake measured by change in volume
57
gas exchange cells and tissue
squamous epithelium-thin and flat, thin endothelium, provides short diffusion pathway, surfactant reduced surface tension and prevents alveoli from collapsing
eyrthocytes- transports gas/oxygen to alveoli
muscles-intercostal muscles, and diaphragm maintain concentration gradient
neutrophil- engulfs and destroys pathogen, protect from infection
ciliated epithelium-goblet and ciliates cells- protect and remove dust, bacteria and spores
cartilage-hold airways open
smooth muscle-constrict and control diameter, of airway, narrows lumen
elastic fibres-recoil and aiding ventilation
58
role and function of the xylem
transport water from roots to leaves, vessels carry water, fibres support plant, parenchyma act as packing tissue to separate and support vessels, lignin is waterproof spirals and deposits in cell walls which cause them to die and become dead, end walls and cell contents decay, leaves long column of dead cells with no contents
59
4 specialisations of xylem
lignin present-waterproof xylem vessel prevents collapse, hard so even if water levels are low it still will not collapse, improves adhesion of water and capillarity, spiral prevents it from being too rigid and allows flexibility
pits-allow water move from one cell to another and leave xylem while passing on living parts
narrow tubes-water column does not break easily and capillary action
no cross walls or cut contents-water flow not imbeded
60
role and function of phloem
tissue used to transport assimilates around the plant, sieve tube element, companion cells, sucrose plates support tube and keep lumen open, also be blocked after injury, infection by substance called callose to seal it off,
61
what are the two components of the phloem and their function
companion cells=really thin walls, very small cells, very dense nuclei and cytoplasm and lots of mitochondria, carry out metabolic processes needed to load assimilates actively into sieve plates
sieve tube elements= no nucleus, very little cytoplasm, perforarted walls called sieve plates, mass flow of sap takes place here
62
types of pathways of water
apoplast-water travels through cell walls
symplast=water travels through plasmodesmata in cytoplasm
vacoular=water travels through vacoules
63
charactieristics of water
-turgor pressure-hydrostatic skeleton for support
-cell expansion
transport of mineral ions and products of photosynthesis in aqueous solution
-evaporation of water helps keep plants cool
-minerals enter root via active transport
-water molecules by osmosis
64
pathways of water features
apoplast=cellulose cell wall is fully permeable
symplast=cytoplasm bridge through plasmodesmata join cytoplasm of adjacent cell
vacoular=water can pass through vacoule
65
what is a casparian strip
waterproof region in cellulose of endodermis-suberin and lignin
66
3 types of movement of water through the stem
Root pressure, transpiration pull, capillary action
67
What is root pressure and how does it work
Mineral ions are actively pumped by active transport into the root, pass through the cortex into xylem, across endodermis, lowers water potential in xylem, draws water into xylem via osmosis, causes hydrostatic pressure to build up and water drawn up and forced up xylem
68
What is capillary action and how does it occur
Adhesion chase the water molecule to stick to the sides of the xylem, as it is narrow forces of cohesion and adhesion cause water molecules to be pulled up xylem as a single column
69
What is transpiration pull as how does it occur
Loss of water from leaves, creates water potential due to concentration gradient, water replaced form xylem, water molecule stick together, due to cohesion, long column, pulled as a chain, creating tension-cohesion tension theory
70
What is the role of lignin in xylem
Strengthen and reinforce xylem to prevent it from collapsing from tension, waterproof substance
71
What is adhesion
Attraction of water molecules to surface of a solid
72
How can different factors affecting rate of transpiration be measured
Light=lamp with water tank to absorb warmth
Heat=heater
Humidity=concealed space
Air movement=fan
73
what are the three main components of insect gas exchange
exoskeleton, spiracle, trachae
74
adaption and function of exoskeleton
little to no gas exchange can take place, no haemoglobin to carry o2, delivers o2 directly to cells and removes co2 the same way
75
adaption and function of the spiracle
along thorax and abdomen, opens where air enters, however this leads to water loss so it opens and closes to minimise loss, occurs when o2 demands are low and the insect is inactive and vice versa
76
adaption and function of the trachae in insects
largest tubes, carry air to body, line with spirals of chitin which tubes open if bent and pressed, impermeable to gas, in cuticle=little gas exchange, branch and form narrower tubes called tracheoles which are small and single enlongated cells with no chitin lining making them freely permeble to gas, small in size therefore spread aroiund tissue next to indivudal cells, move by diffusion, large sa, o2 dissolves in moisture of walls, towards the end there is tracheal fluid which decreases penetration of air for diffusion, all oxygen supplied by tracheal system eg lactic acid build up leads to more water moving out the tracheoles by osmosis, more sa for gas exchange,
77
what are the two adaptions if an insect has large oxygen demands
-mechanical ventilation of tracheal system means that the thorax and abdomen change in pressure and volume therefore air is either drawn in or forced out
-collapsible enlarged trachea act as resevoirs which increase air by dilating and inflating
78
what is the main reason for gills in fish
big and active animals have high o2 demands, sa:v ratio means diffusion would not be enough to supply inner cells, scaly outer does not allow gas exchange, ventilatory system takes oxygen from water and removes the co2 while maintaining one direction flow of water over gills, large sa, good blood supply, thin layers, gill cavity and cover of protective operculum (big flap)
79
what are the two aims of translocation
-phloem loading by apoplast/active process and symplast/passive process
-phloem unloading
80
what is phloem unloading and the two different routes
soluble products of photosyntheiss moved by phloem, active process, sucrose is main carbohydrate, not used as much in respiration therefore it is less likely to be metabolised
symplast route=cytoplasm of mesophyll into siee tubes by diffusion through plasmodesmata, passive, sucrose and water by osmosis in sieve element, increase pressure of water by mass flow
apoplast route= travel through cell wall to companion cells and sieve element by diffusion, down conc gradient maintained by removal of sucrose, in the companion cells, scursoe is moved into cytoplasm across cell membrane and hydrogen ions are actively pumped out into surrounding tissue using atp, return via co transport protein where sucrose is co transported, increase sucrose conc leads to movement through plasmodesmata of linked cells, inner foldings in cell membrane increase sa for active transport, many mitochondria to supply atp, build up of sucrose leads to water moving in by osmosis, build up of turogr pressure due to rigid cell walls, decrease pressure, moves up and down plant by mass flow to sinks, solute accumulation in source phloem leads to increase in turgor pressure, forces sap to regions of low pressure in sinks, higher than human artery as they travel longer metres,
81
what is the process of phloem unloading
sucrose unloaded from phloem at anytime needed, diffusion of sucrose from phloem to surrounding cells, loss of solutes increase water potential of phloem, moves out by osmosis, some water carried to sink, drawn into transpiration stteam of xylem
82
evidence of translocation
-advances in microscopes to view adaptations of companion cells
-mitochondria poisoned=translocation stops
-flow of sugars = 10000 times faster than diffusion alone-active
-use of aphids forces sap out of styler, pressure and flow decreases closer to sink than near source, sucrose conc in sap increases closer to sink than source
83
what are the 6 parts of the fish head
gill arch, gill filament, operculum, buccal cavity/mouth, gill rakers, buccal floor
84
what are the 6 functions of each part of the fish head
-gill arch supports gill filaments,
gill filament is fragile and delicate-where water passes through
-operculum is the covering that prevents damage
-gill rakers-protect gill filaments from debris hitting them
-buccal floor-can move up and down like diaphragm
85
what happens in inhalation for a bony fish
mouth opens, operculum (valve)-closes, buccal walls relaxes and drops, pressure decreases as there is a higher pressure outside, water moves in due to pressure difference, buccal/operculum cavity volume increases
86
what happens in exhalation of bony fish
mouth closes, buccal cavity/operculum cavity volume decreases, pressure increases, operculum valve opens, water moves out, buccal cavity volume decreases
87
what is the total process of inspiration and expiration of bony fish
Mouth opens (operculum is closed)
The buccal cavity floor is lowered
This increases the volume and decreases the pressure of the buccal cavity compared to outside.
Water rushes into the mouth down a pressure gradient, and enters the buccal cavity
Opercular cavity expands.The buccal cavity floor is raised and the walls contract
The pressure inside the buccal cavity is now higher than in the opercular cavity.
Water moves from buccal cavity over the gills into the opercular cavity.
The sides of the opercular cavity move inwards, increasing the pressure.
The mouth is now closed and the operculum opens.
Water rushes into the mouth down a pressure gradient, and enters the buccal cavity
88
where are the lamellae
on top of the filament
89
what occurs in the lamellae
counter current flow of water and blood when oxygen is exchanged; opposite movement of water against flow of blood in gills
90
why is counter current flow used
if not, there would be equilibrium between the o2 conc in water and blood, meaning some blood would not the highest possible amount of o2
91
What is a potometer
Measures water uptake used for photosynthesis, cell turgidity and cell elongation and growth
92
What is the method used when dealing with a potometer
Select a part of the healthy plant which will fit through the bung
Remove debris from stem and cut using scalpel at an angle and under water
Fill the potometer with water whilst blocking the end of the capillary tube
Fill trough with water, add petroleum jelly to bung, under water
Don’t allow leaves to sink below water, no air bubbles if so start again, remove and dry with paper towels
Allow time for the plant to acclimatise
93
What are the 4 measures taken when using a potometer and why
Stem must be cut under water and at an angle to increase surface area and prevent air bubbles entering the xylem
Petroleum jelly to ease bung into opening and create a water tight seal
Assemble underwater to prevent air bubbles which could travel up the xylem and prevent transpiration
Leaves must be dry as water could block the stomata, decreasing the concentration gradient which prevents water leaving
94
What are the 5 precautions taken when dealing with a potometer
All conditions except air movement kept the same
Sensible suggestions to investigate effect of air movement et use of a fan for set time
Fan placed at Different distances from potometer
Control readings in still air allow plant recovery time between different distances
More than one reading for each distance
95
what are the two types of plants and water
hydrophyte (live in water), and xerophyte (live in very little water)
96
what plants are hydrophytes
water lillies, water cresss, duckweeds (on the surface), bulrushes(submerged), yellow iris (submerged)
97
what are the problems with hydroophyte plants
water logging can occur in air spaces that the plant need to survive
98
9 adaptations of hydrophytes
air sacs-float on surface of water
wide, flat leaves-cpautre as much light as possible
reduced structure-water supports leaves, less need for support structures
many always open stomata on upper surface-maximises gas exchange, no risk of loss of turgor, guard cells inactive, in contact with air
very thin waxy cuticle-no need to conserve water so water loss by transpiration is not an issue
small roots-water diffuses directly into stem, less uptake by roots
large sa of stems, root underwater-maximise photosynthesis area and more oxygen to diffuse
aerenchyma=specialised parenchyma in leaves, stem and roots, large air spaces, makes leaves and stem more bouyant, form low resistance internal pathwayfor anoxic (low oxygen) conditions and movement of substance
leaves float-near the surface, light for photosynthesis
99
problems with the aerenchyma
can be in rice, methane produced, contributes to greenhouse effect and climate change, leads to flooded rice paddies, roots water logged, prenumatophores (special aerial roots) grow
100
6 adaptations of insect gas exchange system
1. No lungs, have air sacs
2.no haemoglobin, instead have hemolymph
3.open circulatory system unlike human closed
4.tracheal connects to all tissues and delivers oxygen while removing co2
5.oxygen travels down conc gradient towards cells, carbon dioxide travels down its own conc gradient towards spiracles, passive process
6.large insects use abdominal muscles to help move gases in and out, rhythmic movement while flying to change volume, pump air in and out for ventilation
101
What are the components of the bell jar model
Glass tubing acts as trachea-air travels down to lungs
Bell jar acts as the thorax-responsible for volume and therefore pressure, protection for lungs
Balloons act as lungs-fill with air
Elastic sheet acts as diaphragm-contracts and flattens to change volume and pressure within thorax
102
Positives and Drawbacks to bell jar model
Demonstrates lungs as two balloons, both stretch and recoil, residual volume in both inflate, however balloons are empty while lungs have alveoli
Trachea has air drawn down trachea into lungs which is similar to hard rigid c shaped cartilage where as glass tube is straight, less flexible
Diaphragm moves down and contracts and flattens which changes pressure like elastic sheet, however diaphragm can be dome shaped while elastic cannot, both return to original shape
103
Characteristics of marram grass
Xerophyte, stomata in sunken pits to trap water, thick waxy cuticle reduce water loss, hair reduce air movement which reduces transpiration, dense spongy mesophyll and decrease evaporation, rolled leaves trap water vapour decrease humidity
104
Characteristics of cacti
Widespread and shallow roots, succulent by storing water in stems, ribbed and fluted to expand to take water up, many chloroplasts for photosynthesis
105
Characteristics of hydrophyte plants
Increased air space in stems and leaves to help float, stomata on upper epidermis as it is more exposed to air, submerged widespread leaves, hydrant hoses release water droplet that evaporate
106
What are the characteristics of terrestrial plants
Waxy cuticle to reduce water loss
Stomata abundance and close at night and at the bottom to reduce evaporation
Loses leaves in winter to reduce water loss
107
What is a source
Part of the plant that loads material into phloem or transport systems
108
What is a sink
Part of the plant that material is removed from transport systems or phloem
109
What is active loading
The process of loading sucrose into sieve tubes using atp
110
What is co transporting in phloem
Movement of two different molecules simultaneously
111
the process of translocation
-sucrose enters sieve tube elements
-as water potential decreases enters from xylem
-change in pressure and water potential gradient
-cell sap formed and travels down gradient to the sink
-sucrose leaves sieve tube via diffusion and active transport
-water moves out of sieve tube and out of conc. gradient due to loss of sucrose which increase water potential
-loss of water in sieve tube decreases hydrostatic pressure
112
how assimilates are loaded into the phloem
-pumped by ATPase actively
-active transport of hydrogen ions/protons out of companion cells
-creates hydrogen ion/conc gradient
-faciliated diffusion of hydrogen ions back into companion cell
-sucrose move in with hydrogen ions
-sucrose diffuse through plasmodesmata from companion cell to sieve tube/element
113
what happens in an open circulatory system
-very few vessels for transport medium
-pumped straight from the heart into body cavity/haemocoel
-low pressure, direct contact with tissue and cells for exchange
-transport medium moves back to the heart through an open ended vessel
-mostly in insects where transport medium is haemolymph
114
what does the open circulatory system do in insects
-haemolymph/ transport medium does not carry o2 or co2 but transports food and nitrogenous waste products and cells in defence
-body cavity split by membrane and heart is extended across thorax and abdomen
-circulates however as it cannot maintain a conc gradient, diffusion is inefficient
-the amount of haemolymph flowing to an area of the tissue cannot be varied
115
what are closed circulatory systems
-blood is enclosed in blood vessels, not in direct contact with cells,
-heart pumps blood at high pressure and quickly before returning to the heart
-substances leave and enter the blood by diffusion through the walls of the blood vessels
-the amount of blood entering can be controlled by widening and narrowing the blood vessels, have blood with haemoglobin
-mostly in animals and more specifically mammals
116
what happens in a single closed circulatory system
-blood flows through heart and is pumped out to travel all arouind the body before returning to the heart, travels only once
-passes through two sets of capillaries in different organ systems, substances are exchanged between blood and cells
-as blood pressure drops, blood returns back to the heart slowly to limit efficiency of the exchange processes
levels of circulation are relatively low
117
what circulatory system do fish have and how does it work
single closed circulatory system
-however fish are an exception as they have an efficient one, making them active
-countercurrent gaseous exchange system in the gills that allows their oxygen uptake to be high from water, body weight supported by water, do not need to maintain their own body temp
-reduces metabolic demands and efficient gas exchange makes them active
118
what is the double closed circulatory system and how does it work-mammals
-used by very active mammals that maintain their own temperature
-blood is pumped from heart to lungs to pick up oxygen and unload co2, then return to heart
-blood flows through heart and is pumped out to travel all around the body before returning to the heart again
-therefore blood travels twice, in each circuit, it only passes through one capillary network, which means relatively high pressure and fast flow can be maintained
119
what is the function of elastic fibres in blood vessels
stretch and coil for flexibility
120
what is the role of smooth muscle in blood vessels
contract and relax to change the size of the lumen
121
what is the role of collagen in the blood vessels
structural support to maintain shape and volume
122
what is the role of the arteries
carry blood away from oxygenated heart to tissues, apart from pulmonary and umbilical artery, has high blood pressure,
123
three adaptations of the arteries
elastic fibres withstand the blood pressure to travel to bigger blood volume, recoil and stretch for continuous flow however it cannot eliminate the pulse and surge of blood
smooth lining so blood flows easily
124
what are the arterioles and what are their roles
links arteries and capillaries, more smooth muscle and elastin than in arteries, have little pulse surge, constrict and dilate to control specific blood flow-vasoconstriction and vasodilation
125
what is vasoconstriction
smooth muscle contracts , constricts vessel and prevent blood flow to capillary bed
126
what is vasodilation
smooth muscle on arteriole wall relaxes so blood flows to capillary bed
127
role of capillaries
link arterielles and venules, extensive network in tissue, small lumen one cell thick, gaps in endothelial cells in capillary wall is large so substances pass through into surrounding fluid, apart from cans where there are very tight junctions, short diffusion pathway
128
role of veins
carry deoxygenated blood to the heart , low blood pressure, great volume of bloood transported under low pressure to prevent collapse
129
what is the tunica adventita, tunica media, and tunica intiva
adventitia= collagen
media-muscle and elastic
intivia=connective tissue and elastic tissue, one cell thick
130
where are veins found
close to the surface of the skin
131
what causes varicose veins
bulges in the skin, caused by loss of stretch from collagen
132
what are bacteria and what are the types of bacteria
prokaryotes, no membrane bound organelles, include bacilli, cocci, vibrios, spirialli, and spirochaetes
133
how can bacteria be identified
through gram staining
-gram positive-appear purple/blue under light microscope eg mrsa
-gram negative-appear red under light microscope eg e coli
134
how do bacteria affect host cell
produces toxins when reproducing which damages and posions host cell, breaks down cell membrane and genetic material and enzymes, cannot divide, occur as a by product
135
what are fungus and what makes them pathogens
eukaryotic organisms which cannot photosynthesise and digest food extracellularly-feed on decaying matter, some are parasitic, occur on ,eaves and stop them from photosynthesising, quickly reproduce spores which can be spread over huge distances eg crops, digest living cells and destroy, response of body to damage=symptoms
136
what are protista and how do they act as pathogens
eukaryotic organism, unicellular, wide variety of feeding methods, parasitic eg malaria and mosquitoes, some take over cells, break them open and digest and use their contents as they reproduce, do not take over host cell genetic material
137
what are viruses and how do they act as pathogens
non living infectious agents, have some rna and dna surrounded by proteins, invade living cells, takeover dna and make more viruses, reproduced rapidly evolve by developing adaptions to their host, can act as bacteriophages (attack bacteria), take over cell metabolism, viral genetic mateiral gets into host cell and inserted into host dna, virus uses host cell to make new viruses which burst out of cell, destroying it, spread to infect others
138
how does viral replication occur
1.attatches to host cell
2. inserts viral nucleic acid
3.replication of nucleic acid
4.synthesis of viral proteins
5. assembly of viral particles
6.lysis of host cell
139
factors affecting transmission of pathogens in animals
-overcrowding
-poor nutrition
-compromised immune system eg aids/hiv
-poor disposal of waste (breeding sites)
-climate change as new vectors thrive in increased temp
-culture and infrastructure
-socioeconomic factors eg poorly trained health workers
140
factors affecting transmission of pathogens in plants
-planting crops that are susceptible to disease
-overcrowding as it increases contact
-poor mineral nutrition decreases resistance
-damp, warm conditions increase survival and spread
-climate change allows animal vectors to spread and rainfall and wind increase
141
three types of animal direct transmission
contact=kissing, contact of bodily fljids, skin to skin, microorganisms from feces
inoculation=break through skin, animal bite, puncture wound/share needles
ingestion=contaminated food/drink, mouth from hands
142
three types of indirect transmission in animals
formites=inanimate objects eg bed transfers pathogens
droplet/inhalation= saliva/mucus expected from mouth while talking, coughing and sneezing
vector=from one host to another eg mosquitoes or water
can be mitigated by washing hands
143
how can plants be infected by direct transmission of pathogens
contact with a diseased plant eg in a crop, eg ring rot, tobacco mosaic virus, tomato and potato blight, black sigatoka
144
5 types of indirect transmission of pathogens in plants
-leave pathogens in soil or composting soil in the next crop, so cycle continues
-wind-bacteria, virus, fungus carried in wind
-water-spores swim in surface film, of water, carry pathogens in rain droplets
-animals=carry pathogen and spore from one plant to another in feeding-aphids
-humans=hands, clothing, formites, feeding process and transporting
145
What is the pericardium/ in elastic pericardial membranes
Sac which surrounds the heart to protect it, reduces friction against ribs, prevents heart from over distending with blood
146
What are the coronary arteries
Supply blood to the heart, if blocked, leads to a heart attack or myocardial infarction
147
What are the four chambers of the heart
Right atrium, right ventricle, left atrium, left ventricle
148
What are the four blood vessels
Vena cava, pulmonary artery, aorta, pulmonary vein
149
What are the four valves
Pulmonary/ semi lunar- leads to pulmonary system and outside of heart+leads to lungs
Bicuspid/mitral/atrioventricular-two flaps
Tricuspid/atrioventricular-three flaps
Aortic/semi lunar-leads to aorta and outside of the heart
150
What is the job of the septum
Prevents deoxygenated blood mixing with oxygenated
151
How is the aortic valve opened
Pushed opened by oxygenated blood leaving the heart
152
What is the job of the two pumps of the heart
Right pump= Deoxygenated blood from body flows into the right side of the heart which pumps it to the lungs
Left pump=Oxygenated blood from the lungs returns to the left side of the heart which pumps it to the body
153
What is cardiac muscle
Ontracts and relaxes in a regular rhythm, does not get fatigued like skeletal muscle, supplied oxygenated blood from coronary arteries to keep contracting and relaxing
154
Movement of deoxygenated blood through the heart
Enters right atrium from upper body and head in the superior vena cava or from lower body from inferior vena cava at relatively low pressure,
blood flows in which increases prsssure until tricuspid value to let blood pass through into right ventricle,
when both atrium and ventricle are filled the blood the atrium contracts which forces the blood into the right ventricle which stretches the ventricle walls and contracts,
the tricuspid valve closes which prevents backflow to atrium , and pumps deoxygenated blood through the semilunar valves into the pulmonary artery which transports it to the capillary beds of the lungs,
these semilunar valves prevent backflow of blood into the heart
155
Movement of oxygenated blood in the heart
Oxygenated blood from lungs enters left atrium from pulmonary vein,
pressure in atrium builds leading to bicuspid valve opening between left atrium and left ventricle
which fills with oxygenated blood, when both are filled the atrium contracts which forces all oxygenated blood into left ventricle
which also contracts and pumps oxygenated blood through the semi lunar valves into the aorta and around the body,
as the ventricle contracts the tricuspid valve closes preventing the backflow of blood
156
Why is the muscular wall of the left side of the heart thicker
Lungs are relatively close to the heart and are smaller than the rest of the body so the right side of the heart have to pump over a short distance and only has to overcome the resistance of pulmonary circulation, left has to produce enough force to overcome resistance of aorta and arterial system, move blood under pressure
157
How do the right and left side of the heart fill
Together
158
What is the role of the tendinous cords in the heart
Make sure the valves are not turned inside out by pressure exerted when the ventricle contracts,
159
4 types of blood vessel graphs
-vessel diameter
-total cross sectional area of vessels
-average blood pressure-sytolic pressure= highest pressure, diastolic pressure= lowest pressure
-velocity of blood flow
160
how to calculate stomatal density
Step 1: Calculate the radius of the field of view.
Step 2: Calculate the area of the field of view.
Step 3: Divide the mean number of stomata by the area of the field of view to calculate density.
Step 4: Round to the required precision (nearest whole number)
161
What is an electrocardiogram
Can measure the spread of electrical excitation through the heart as a way of recording when the heart contracts, does not directly measure the electrical activity of your heart as it measures tiny electrical differences in your skin as a result of the electrical activity of the heart
162
How does the electrocardiogram
Electrodes stuck painless.y to clean skin to get the good contacts needed for reliable results, signal from each of the electrodes is fed into the machine, producing an ecg, bell with treatment and diagnosis, recognise abnormalities
163
4 abnormalities of the heart recognised in the ecg
1. Tachycardia-when heartbeat is very rapid, over 100 bpm, normal in exercise or when scared or angry, abnormal if caused by electrical Control of the heart
2.bradycardia-when heart rate slows down to below 60 bpm, when fit as training makes the heart beat more slowly and efficiently, may need pacemaker if severe
3.ectopic heartbeat- extra heartbeats out of normal rhythm, most people have one a day input can be linked to serious conditions if frequent
4.atrial fibrillation-arrhythmia m abnormal heartbeat , rapid electrical impulses generated on atria contract very fast or fibrillation up to 400 times a minute, do not contract properly and pass impulse to ventricles where they contract less often as a result blood is not pumped effectively
164
what is cardiac output and its equation
volume of blood pumped by ventricle each minute
heart rate x stroke volume
165
what is the equation of heart rate and stroke volume
heart rate=beats /min
stroke volume=volume/beats
166
what is heart rate and stroke volume
heart rate=no of cardiac cycles per minute
stroke volume= vol of blood pumped out heart in one cardiac cycle
167
what is blood pressure and how is it measured
systolic and diastolic
normal=<120/<80
elevated=120-129/<80
high stage 1=130-139/80-89
high stage 2=140-180/90-12
hypertension=>180/>120
168
why are some high cardiac outputs normal
the fitter you are the higher as thicker and stronger ventricle walls are present, blood supply meets high metabolic demands
169
what is the lub dub sound
lub=av valve closes, sl valve opens
dub=av valve opens, sl valve closes
170
where is the avn and san found
san-top left of ra, avn= between septum of the two atria/ bottom right of right atrium
171
how is it atria contracts before ventricles
0.1s delay of electrical impulse
172
where does the electrical impulse in coordination start
bottom up
173
coordination of cardiac cycle process
The SAN can create a wave of electrical activity, which spreads out rapidly over the whole of the atrial walls, across internodal pathways.
Cardiac muscle in the atrial walls respond to this excitation wave and contracts simultaneously.
Blood is forced in to the ventricles (remember the AV valve was already open before)
After a short delay of 0.1s, the AVN picks up the excitation wave after it has spread across the atria.
The impulse in directed down each of the two bundle of His branches (a continuation of the specialised tissue of the AV node) , which run down the Septum. They are fast-conducting muscle fibers/ cells. The are also called the atrioventricular bundle
Once the impulse reach the apex of the heart, the impulse spreads to the purkyne / purkinje fibre
The fibres direct the impulse back up the walls of the ventricles
Cardiac muscle in the ventricle walls respond to this excitation wave and contracts simultaneously, from the bottom up
The SL valves are forced open and the blood leaves the ventricles and enters the arteries
174
role of oxygen in transport
erythrocytes have a biconcave shape, meaning a larger sa is available for diffusion, pass through narrow capillaries, formed continuously in bone marrow, mature rbc enter circulation i and lose nuclei to maximise haemoglobin which carries oxygen and is a large globular conjugated protein-4 peptide chains and iron haem prosthetic group-300 million haemoglobin
175
relation between transporting oxygen and rbc
rbc enter capillaries in lungs where oxygen is low, steep conc gradient inside rbc than air in alveoli means oxygen moves in and binds to haemoglobin as done as one oxygen molecule binds to the haem group it changes shape to make it easier for more to bind-positive cooperativity, steep diffusion gradient maintained until saturated with oxygen, reversed when blood reaches tissue and oxygen moves out and down the conc gradient
176
what is the bohr effect
as partial pressure of co2 increases, haemoglobin gives oxygen up more easily,
177
transport of co2 in blood
active tissue with high partial pressure of co2 , haemoglobin gives up o2 more readily, lungs which have a low co2 in air, o2 binds to haemoglobin easily
178
what is fetal haemoglobin
when fetus is developing in veins-completely depend on mother for oxygen, oxygenated blood from mother runs close to deoxygenated fatal blood in placenta, if it is the same affinity=little blood is transferred, if affinity is high=fatal so it removes oxygen from maternal blood as they move past each other
179
carbon dioxide in rbc
-5% dissolved in plasma, 10-20% combine with polypeptide chains to form carbaminohaemoglobin, 75-85% convert to hydrogen carbonate react slowly in rbc cytoplasm, most co2 diffuses into blood in form of hydrogen carbonate, react slowly to form carbonic acid, dissociates to hydrogen ions and hydrogen carbonate, slow in cytoplasm due to carbonic anhydrase-reversible
180
what is the chlorine shift
-charged hydrogen carbonate ions move out rbc into plasma by diffusion down conc gradient and chloride ions move into rbc to maintain electrical balance
-maintain steep conc gradient for co2 to diffuse from respiring tissue into rbc
-blood leaves lung which decreases co2 conc, carbonic anahydrase catalyses reverse to break down carbonic acid to co2 and h2o, hydrogen carbonate, diffuse back into rbc =and react with hydrogen ions to form carbonic acid, repeats until broken drown , carbonic anahydrase releases free co2, which diffuse out the lungs, chloride ions diffuse out and back into plasma down a electrochemical gradient
-haemoglobin acts as a buffer to prevent change in ph, by accpeting free hydrogen ions in reversibler reactions to form haemoglobinic acids
181
What is in the bloods plasma
Yellow liquid, contains dissolved glucose and amino acids, mineral ions, hormones, large plasma proteins including albumin which maintains osmotic potential and fibrinogen which involves blood clotting, and globulin which transports and is in the immune system, plasma also transports rbc and wbc, carry platelets(fragments of large cells called megakaryocytes in red bone marrow involved in clotting), 55% of blood is plasma
182
7 components of plasma
-transport o2 to, co2 from respiring cells
-digested food from small intestine
-nitrogenous waste products from cells to excretory organs
-hormones
-food molecules from storage compounds
-platelets to damaged areas
-cells and antibodies involved in immune response
183
What is tissue fluid
Substances dissolved in plasma which cannot pass through fenestration in the capillary wall, eg large plasma proteins, has an osmotic effect which increase solute potential, fluid is forced out which fils spaces between cells, no rbc or plasma proteins, diffusion between blood and cells
184
Process of the formation of tissue fluid
water has tendency to move in the blood in capillaries from surrounding fluid by osmosis, oncotic pressure of -3.3 kpa, balance of force changes as blood moves toward venous system, hydrostatic pressure decrease as fluid has moved out,pulse is lost, on optic pressure is more than hydrostatic pressure so water moves back into capillaries by osmosis, 90% is back in blood vessels
185
What is lymph
Tissue fluid which does not return to capillaries instead into blind ended tubes and lymph capillaries- has less oxygen and nutrients than plasma and tissue fluid, has fatty acids from
186
3 features of lymph
1. Join into larger vessels which transport fluid by squeezing body muscles
2.one way valves to prevent backflow
3.lymph returns it blood by flowing into right and left subclavian veins
187
What are lymph nodes
Where lymphocytes build up and produce antibodies then pass them into blood, intercept bacteria and debris, digested by phagocytes as a defence mechanism
188
What is the cardiac cycle
Series of pressure changes within the heart, result in blood movement, different chambers of the heart as a whole
189
What are the three stages of the cardiac cycle
1.atrial and ventricular diastole (filling )= chambers are relaxed and filling with blood 2.atrial systole (contraction) =atria contract and remaining blood is pushed into ventricle 3.ventricular systole (contraction)= ventricles contract and push blood all through aorta and pulmonary arteryWhat is cardiac diastoleFilling, all chambers are relaxed and blood flows into the heart
190
What is atrial systole/ ventricular diastole
Atria contracts, pushes blood into ventricles
191
What is cardiac diastole
Filling, all chambers are relaxed and blood flows into the heart
192
What is atrial diastole/ ventricular systole
Atria relaxes, ventricle contracts and pushes blood out
193
what happens in the atrioventricular valve in the cardiac cycle
-pressure in ventricles rapidly drops below pressure in atria -blood in atria pushes the av open -blood enters heart flows through atria and into ventricles -pressure in atria and ventricles rises slowly as they fill with blood -valves remain open while atria contracts, but close when the atria relaxes -av closure is due to swirling action in valves when the ventricles become full -when the pressure rises above that in the atria and blood moves upwards -movement causes the valves pockets to fill and keep closed -tendious cords attatched to valves prevent them from turning inside out -prevents blood flowing back to atria
194
what happens in the semi lunar valves in the cardiac cycle
-pressure is initially higher in the artieries than ventricles -semilunar valve is closed -ventricular systole raises blood pressure in ventricles quickly -pressure in ventricle sis now above arteries so semi lunar valve is piushed open -blood is under high pressure so it is forced out the ventricles -once walls stop contracting the heart muscles relax (diastole) -elastic tissue in ventricle walls recoil -muscle stretches out again and ventricle returns to original size -pressure in ventricles fall to below the pressure in the arteries so blood flows into the ventricles -semi lunar valve is pushed closed by blood which prevents back flow to ventricles -pressure wave when semi lunar valve=pulse
195
what is diastole in the cardiac cycle
heart relaxes, chambers fill with blood, volume and pressure increase, heart fills, artery pressure=minimum
196
what is systole in the cardiac cycle
atria contracts (atrial systole),then ventricle contracts (ventricular systole), pressure increases, blood is forced out to lungs, pressure is low at the end, artery pressure=maximum
197
what is aortic pressure in the cardiac cycle
pressure increases, ventricles contract and blood is forced out aorta, gradually falls, recoil sciton (essential so blood is continously delivered to tissue), causes temp rise in pressure and relaxation
198
what is ventricular pressure in the cardiac cycle
pressure=low at first but ventricle gradually fills with blodd, left av closes, pressure increases as thick ventricular walls contract, pressure increases above aorta, blood forced into aorta, pressure decreases as ventricles empty and relax
199
what is atrial pressure in the cardiac cycle
pressure is low as thin atrium walls cannot produce force, highest when contracting, drops when left av closes and its walls relax, atria fills with blood, gradual increase in pressure, slight drop when left av opens and blood moves into left ventricle
200
what is ventricular pressure in the cardiac cycle
pressure=low at first but ventricle gradually fills with blodd, left av closes, pressure increases as thick ventricular walls contract, pressure increases above aorta, blood forced into aorta, pressure decreases as ventricles empty and relax
201
Cardiac cycle atrial systole-atria contracts
Cardiac cycle atrial systole-atria contracts -ventricle relaxes -pressure in atria is highest, compared to ventricle due to contraction -av still open, sl closed -blood flow atria to ventricles actively, atria empties blood and ventricles fill -ventricles begin to contract -atria begin to contract -pressure in ventricles is highest as it is full with blood -av is forced shut and sl to increase pressure in ventricle -blood flow means atria is empty and ventricle is full Cardiac cycle diastole -no contraction -atria and ventricles relax -pressure is highest in veins and arteries have more pressure than ventricles -valves closed, sl valves closed to prevent backflow -blood flow from veins into atria Pressure is then highest in atria, compared to ventricles, due to blood flowing in, Av valves open, sl still closed, Blood flow from atria to ventricles passively
202
What is the heart rhythm
Myogenic=has its own intrinsic rhythm at 60bpm, prevents body wasting resources, average adult resting=70 bpm due to factors such as exercise, excitement and stress
203
Cardiac cycle ventricular systole
-ventricles contract -atria relaxes -pressure is hugest I’m ventricles compared to arteries due to contraction -av closed, sl opened due to ventricular pressure -blood flows from ventricles to pa/aorta
204
What are the two types of nodes
-sino atrial node -atria ventricular node
205
What is the san atrial node
A wave of electrical excitation begins in pacemaker area causing atria to contract and initiate heart beat, Layer of non coruscating tissue prevents it passing to ventricles
206
What is the atrioventricular node
Picks up electrical activity from Sam , imposes slight delay before stimulating bundle of his (bundle of conducting tissue made of purkyne fibres), penetrate through septum, splits into two branches, conducts wave of excitation to apex, spread out through ventricle walls and triggers contraction of ventricles at apex, allows efficient ventricle emptying
207
What type of protein is haemoglobin
Globular
208
How many polypeptide chains make up one molecule of haemoglobin
4 subunits-2 alpha polypeptide chains and 2 beta polypeptide chains
209
Which molecule is found at the centre of each prosthetic group
Heme with iron ion
210
What does haemoglobin do
Transport oxygen around the body
211
How many oxygens bind to each haemoglobin
8 atoms or 4 molecules per haemoglobin
212
What is oxygen from haemoglobin used for
Aerobic respiration
213
What does it mean if haemoglobin is saturated
It has as many oxygen molecules as it can carry
214
What does association and disassociation mean
Association is when oxygen is binded or loaded
Disassociation is when oxygen is off loaded or release
215
What does high affinity mean
Highly attractive to oxygen, readily binds
216
What is partial pressure
Measure of oxygen concentration,
Pressure exerted by oxygen with a mixture of gases
217
Where is high partial pressure
Lungs as high conc as it loads with conc gradient
218
Where is low partial pressure
Veins and muscle tissue, blood leaves lungs, conc formed and unloading oxygen
219
Myoglobin v haemoglobin
Myoglobin has 1 subunit and haemoglobin has 4, myoglobin has 1 heme group and haemoglobin has 4 heme group, myoglobin is in the muscles and haemoglobin is in. The rbc, both can dissociate from 02 reversibly
220
What is the role of haemoglobin in controlling hydrogen ions in transport of co2
Acts as a buffer,accepts h ions to form haemoglobinic acid which prevents the ph decreasing
221
Explain how haemoglobin acts as a buffer
-co2 and water form carbonic acid
-carbonic acid dissociates into hydrogen ions
-hydrogen ions bind to haemoglobin
-co2 is carried as hydrogen carbonate ions
222
What associates the easiest
Lungs as oxygen conc is the highest
223
What associates the hardest
Tissues as oxygen conc is the lowest
224
What happens along dissociation curve shifting to the right
1. 1st o2 molecule is difficult to bind with in low partial pressure and needs a large increase of 3-4 kpa which increase oxygen tension, and increase diffusion gradient, able to bind, causes change in shape which is called the conformational change which increases affinity of other 3 haem groups
2.2nd and 3rd oxygen molecules bind easier due to conformational change in first oxygen, smaller increase of 3 kpa (7 altogether) is needed, haemoglobin is at 75% saturation, across smaller partial pressure- steep
3.4th oxygen molecule is near saturation and the diffusion gradient is low so it struggles to bind, line levels off as changes of binding is lower, increased partial pressure is needed
225
What happens to a dissociation curve which is shifting t to the left
Same concept as shifting to the right but inverted- at high partial pressure there is very little dissociation at medium partial oppressive the curve becomes teeep,as oxygen is beginning To be released to respiring tissues but a Small decrease in partial pressure causes a large decrease in saturation, at low partial pressure dissociation slows as there are few oxygen molecules left on the binding sites and ant the release of the final oxygen molecule is more difficult
226
How does co2 move into the lungs
Co2 levels are low so hco3, diffuses back in and chloride out, hydrocarbonate gains hydrogen ions back reforms carbonic acid, carbonic acid broken down by carbon a hydrate and splits into water and co2, co2 diffuses out
227
How does dissociation occur in a dissociation curve
The first oxygen wants to hold on as long as possible so other body parts can get it
Dissociation of the 2nd and 3rd Is easier due to decreased affinity
The last oxygen is difficult to bind as less space is available
228
Where is the highest partial pressure of carbon dioxide
Respiring muscle tissue
229
Lowest partial pressure of co2
Lungs
230
How does hydrogen ions affect dissociation
Hydrogen ions from carbonic acid bind to haemoglobin which changes the quaternary structure and reduces oxygen affinity, making dissociation more likely, encourages dissociation unit haemoglobin and oxygen
231
What is the Bohr effect
Carbon dioxide increases, affinity for oxygen decreases, oxygen dissociates at a higher partial pressure of oxygen,
232
How does the Bohr effect affect the dissociation curve
causes the curve to the right as co2 increases during exercise and haemoglobin affinity for oxygen decreases, drops oxygen at a lower pressure carry any longer, release oxygen sooner in transport of co2
233
What does the leftward shift on the dissociation curve represent
Haemoglobin has a higher affinity for oxygen, releases it less readily to it any given partial pressure of oxygen, haemoglobin is more saturated with oxygen
234
Factors that cause leftward shift in dissociation curve
-higher ph-less acidic, reduces Bohr effect, causes haemoglobin o release less o2
-lower carbon dioxide levels-less hydrogen ions in blood, reduce Bohr effect, decrease temp which leads to left shift
-foetal haemoglobin= increase affinity of oxygen, shift left, oxygen from mothers blood
235
Why does leftward shift of dissociation curve occur
indicates a higher oxygen in lungs , decreased release in tissue where oxygen is lower, advantageous where oxygen demand is high in tissues eg vigorous exercise, organisms are adapted to low oxygen environments as have left shifted curves to better load oxygen in lungs
236
when does the dissociation curve shift left
-haemocymin
-myoglobin-very high affinity
-high altitude
237
how does the colour of blood relate to in dissociation curve
different organisms, different colour of blood such as blue blooded animals eg squid and green eg crustceans, relates to type of haem inside blood- eg haemocymin
238
