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Biology > Gas exchange > Flashcards

Gas exchange Flashcards

1
Q

how does distance diffusion, SA, volume and SA:vol ratio vary with increasing organism size

A
  1. diffusion distance increases with increasing organism size
  2. SA increases by factor ^2
  3. Vol by a cubed factor
  4. SA:Vol ratio decrease as distance to diffuse to middle of organism increases making it impossible to get enough oxygen the body needs from this
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2
Q

how does the level of activity of an organism related to demand for oxygen and glucose

A

as activity increases, the need for energy increases. Requires a higher rate of respiration so a higher demand for oxygen and glucose.

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3
Q

how is volume related to the demand and surface area is related to supply and why adaptations are needed for supply to meet demand as organisms increase in size

A
  1. as volume increases demand increases as more respiring cells needing oxygen and glucose
  2. as SA increases it increases supply as more diffusion area
  3. simple surface area not adequate for large volumes so adaptations occur to increase SA for larger exchange surfaces
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4
Q

why do organisms need specialized exchange surfaces

A

larger volumes so their SA:Vol ratio is too small to meet demand for high activity of organisms

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5
Q

4 features of efficient exchange surfaces

A
  1. thin membrane - decrease diffusion distance
  2. large surface area - overcome SA:Vol ratio
  3. good blood supply - maintains high conc gradient
  4. well ventilated - helps to maintain high conc gradient
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6
Q

state Fick’s law

A

Rate of diffusion is proportional to
(SA x conc. gradient)/Thickness of Barrier
Ventilation and blood supply affect conc. grad.

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7
Q

describe the structure and function of the nasal cavity

A

large surface area with good blood supply
hairy lining which secretes mucus to protect delicate lung tissue from infection
moist surface increases humidity to prevent evaporation at exchange surface

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8
Q

describe the structure and function of the trachea, bronchi and large bronchioles

A

cartilage rings to keep open airways open and stop them collapsing (small bronchioles have no cartilage)
cilia and goblet cells work together to trap mucus and sweep it away
smooth muscle and elastic fibres allow diameter of tube to change e.g. o increase vol of oxygen

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9
Q

describe the structure and function of the alveoli

A
  1. tiny sacs - main gas exchange surface in the body
    200-300 micrometers
  2. flattened epithelial cells - thin diffusion distance
    elastic fibres allow alveoli to stretch as air is breathed in when return to resting size they squeeze air out - elastic recoil
  3. good blood supply - capillaries only 1 cell thick maintain conc gradient and short diffusion distance
  4. squamous epithelial - thin and moist - dissolve gases for increased diffusion
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10
Q

how do the cilia and goblet cells of the trachea and bronchus work together to protect the lungs

A

goblet cells produce mucus which traps dust particles etc. from the air, cilia then work to sweep out of the trachea to be swallowed and digested protecting lungs from infection

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11
Q

what is the importance of elastic fibres and lung surfactant in the function of the alveoli

A

elastic fibres - spring back to normal size to push air depleted of oxygen out of lungs
lung surfactant - reduces surface tension - prevent alveoli from sticking together when breathing in

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12
Q

how is the mammalian gaseous exchange system adapted to be efficient

A

large surface area - lots of alveoli
good blood supply - network of capillaries
ventilated - maintains conc gradient
short distance - thin + 1 cell thick

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13
Q

define the terms breathing, ventilation and gas exchange

A

is the behavior/ action involves muscle contraction and relaxation
ventilation - flow of air in and out of lungs
gas exchange - diffusion of oxygen and carbon dioxide in and out of the blood

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14
Q

describe the process of inspiration/breathing in

A

an active process
active process
1. diaphragm contacts and flattens
2. external intercostal muscle contact moving rib cage upwards and outwards
3. volume of thorax increases and so pressure decreases
4. due to lower pressure in thorax than outside air is brought into lungs equalizing the pressure.

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15
Q

describe the process of normal expiration/breathing out

A

passive process

  1. diaphragm relaxes returning to domed shape
  2. external intercostal muscles relax so ribs move downwards and inwards
  3. elastic fibres of alveoli relax
  4. volume of thorax decreased and so pressure increased to more than atmospheric air so air drawn out of lungs
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16
Q

how is forced expiration different from normal expiration?

A

uses energy so active process

  1. internal intercostal muscles contract pulling ribs down hard and fast
  2. abdomen muscles contract bringing diaphragm up to increase pressure rapidly
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17
Q

state 3 pieces of equipment used to measure the functioning of the lungs

A
  1. peak flow meter - used to measure rate air can be forced out of the lungs often used on people with asthma
  2. vitalographs - more sophisticated peak flow meter - breath out as hard and as fast as they can into mouthpiece produces a graph with how forced and quick air way breathed out - forced expiratory volume in 1 second
    spirometer - floating chamber on water which is connected to a pivot so it can move when you inhale and exhale drawing a trace on a rotating drum.
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18
Q

define tidal volume

A

volume of air moved into or out of the lungs in one normal breath when normally breathing (500cm^3)

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19
Q

define vital capacity

A

maximum volume of air that can be exchanged in one breath

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20
Q

define inspiration reserve volume

A

maximum extra volume that can be inhaled after a normal breath in

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21
Q

define expiratory reserve volume

A

maximum volume that can be exhaled after normal exhalation

22
Q

define residual volume

A

volume of air remaining in the lungs after normal expiration

23
Q

define total lung capacity

A

volume in the lungs at maximum inhalation

24
Q

define breathing rate

A

number of breaths in a minute

25
Q

define ventilation rate

A

volume of air moved into and out of the lungs in a minute

26
Q

equation including ventilation rate, breathing rate and tidal volume

A

ventilation rate = breathing rate x tidal volume

27
Q

how is a spirometer trace different from a graph showing changes in lung volume during breathing

A

spirometer does no show residual volume

inspiration and expiration are opposite ways up as floating chamber moves down as volume increases

28
Q

how is a spirometer trace different when at rest compared to when exercising

A

larger and closer together troughs and peaks

29
Q

how does tidal volume and breathing rate link to oxygen uptake and what is the importance of this during exercise

A

breathing rate and tidal volume increasing means more air is entering the lungs and so more oxygen can diffuse into RBC which is essential during exercise as the need for oxygen for respiration increases so more air must enter and leave the lungs

30
Q

define exoskeleton

A

external skeleton of some organisms including insects

31
Q

define spiracle

A

small openings along the abdomen and the thorax to control the amount of air entering and leaving gaseous exchange system and to control the amount of water lost through the gaseous exchange system

32
Q

define trachea

A

larger tubes of the respiratory system held open by cartilage

33
Q

define tracheoles

A

smaller tubes of the respiratory system where gas is exchanged - cells surround them so oxygen can diffuse straight into the centre of the cell and carbon dioxide diffuse into them

34
Q

define tracheal fluid

A

fluid at the ends of tracheoles which control surface area for gas exchange and water loss

35
Q

describe the structure of an insect gas exchange system and how oxygen reaches body cells

A

air enters through open spiracles branching networks from trachea to tracheoles allow oxygen to be diffused directly into the centre of the cell

36
Q

why do insects keep spiracles closed when oxygen demand is low

A

insects will keep spiracles closed when oxygen demand is low to prevent water loss

37
Q

adaptations of the insect gas exchange system to make it efficient

A
  1. large surface area with lots of branching and vast number of tracheoles
  2. short diffusion distance - tracheoles small and right close to cells
  3. conc gradient maintained by use of oxygen in the cell
38
Q

how does activity change the volume of tracheal fluid in the tracheoles

A

as activity increases- anaerobic respiration increases lactic acid causes water to leave tracheal fluid by osmosis increases surface area for diffusion of oxygen into cells

39
Q

two adaptations of active insects to increase efficiency of gas exchange system

A

use abdominal pumping to move air in and out

when active muscles in the thorax and abdomen ventilate tracheal system forcing air in and out of air sacs

40
Q

what are the advantages and challenges of gas exchange under water

A
  1. no water loss problem
  2. water supports and separates structures so no need for cartilage
  3. smaller amount of oxygen available
  4. water denser and so requires more energy to change direction hence why fish are a one way system
41
Q

define operculum

A

bony flap covering gills of bony fish part of mechanism that maintains constant flow of water over gas exchange system

42
Q

define buccal cavity

A

space behind the mouth

43
Q

define opercular valve

A

flap that allows operculum to be moved out whilst keeping it closed

44
Q

define gill arch

A

bony structure that supports gill filaments

45
Q

define gill filament

A

thin projection from gill arch causing large surface area

46
Q

gill plate

A

raised plates on surface of gill filament which In total increase surface area for gaseous exchange

47
Q

describe the mechanism of ventilation in bony fish

A

Inspiration:
Mouth open and floor of buccal cavity lowered
Expansion of buccal cavity reduces pressure causing water to enter via mouth (buccal pressure pump)
Opercular valve closed and operculum moved outwards
Expansion of opercular cavity reduces pressure causing some water to flow over gills into opercular cavity (Opercular pressure pump)

Expiration:
Mouth closes and floor of buccal cavity raised
Compression of buccal cavity increases pressur causing water to flow over gills into opercular cavity (Buccal pressure pump)
Opercular valve opens and operculum moved inwards
Compression of opercular cavity increases pressure causing water to flow out of opercular cavity

48
Q

adaptations of bony fish gaseous exchange

A

gill filaments and lamellae increase surface area for gaseous exchange
lamellae thin and surrounded by capillaries so short diffusion distance
countercurrent system maintains concentration gradient as oxygenated water replacing deoxygenated water and flow of blood replacing oxygenated blood

49
Q

define countercurrent system

A

way of exchanging materials or heat when two components flow in opposite directions to each other

50
Q

define parallel exchange system

A

exchange between two fluids when the two fluids run in adjacent tubes next to each other

Biology (11 decks)

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