4.3 Gas Exchange Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

give features of effective gas exchange

A

large surface area
thin layer - minimise diffusion distance
rich blood supply
moist + permeable surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is the main mammalian gas exchange organ?

A

the lungs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

how are the alveoli adapted for gas exchange?

A

provide a large surface area
made up of a thin layer of epithelial cells- short diffusion pathway
steep concentration in gradient- capillaries have deoxygenated blood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is the purpose of having elastic connective tissue in the alveoli?

A

helps to force air out of the lungs which are stretched when you breathe in- elastic recoil

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

describe inhalation as fully as possible

A
  • is an active process
  • muscles around diaphragm contract so it is lowered
  • intercostal muscles between ribs also contract so ribcage moves up + out
  • volume of chest cavity increases
  • pressure in chest cavity decreases
  • pressure is lower than atmosphere so air moves into lungs in order to equalise pressure
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

describe exhalation as fully as possible

A
  • is a passive process
  • muscles around diaphragm relax so it moves in
  • intercostal muscles around ribs also relax so ribs move in and elastic fibres return to normal length(in alveoli)
  • volume of chest cavity decreases
  • pressure in chest cavity increases
  • pressure is higher than atmosphere so air moves out of lungs to equalise pressure
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

name 3 gas exchange organs in insects and explain the function

A

spiracles - site of entry + exit of respiratory gases
tracheae - large tubes that carry air into body, supported by chitin spirals which make it impremeable to gases
tracheoles - single elongated cells with no chitin (permeable) - where most gas exchange occurs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

how does the insect respiratory system work?

A
  1. air enters system through spiracles (the spiracles are a site of water loss so spiracle sphincters are kept closed as much as possible)
  2. air moves along trachea + tracheoles via diffusion
  3. large network of tiny tracheoles gives large surface area - most gas exchange occurs here
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

give two features of active insects

A

have high energy demands

have 2 methods of ventilation; mechanical ventilation and collapsible tracheae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

describe mechanical ventilation

A

air is pumped into tracheal system.
spiracles open and insect makes muscular pumping movement of abdomen
movements change volume and pressure in body so air is drawn in and out

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

describe collapsible tracheae

A

increases the volume of air moved through the system

ventilating the movement of abdomen and inflate + deflate the tracheae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what happens if the insect is very active?

A

needs more oxygen, lactic acid builds up in muscle tissue
this affects osmotic concentration os cells so water moves out of tracheoles + into cells via osmosis
more surface area for gas exchange

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

describe gas exchange in water

A
  • water is denser than air + contains less O2, so diffusion rates are lower
  • gas exchange system of land animals would not work of f fish
  • in gills, water only has to flow over them in one direction - ventilation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

describe the process of ventilation in fish

A
  • pressure in mouth cavity is reduced by floor of mouth being lowered + operculum moved outwards
  • operculum acts as a valve as it is pressed against the body by higher outside pressure so water enters through mouth to equalise pressure
  • volume of mouth cavity decreases + pressure increases by raising floor of mouth- valve in mouth prevents water from leaving
  • increased pressure opens the operculum + water leaves- passes through gill filaments where gas exchange occurs
  • ensures continuous flow of water over gills
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

adaptations of gills

A
large surface area
rich blood supply
thin walls
countercurrent exchange system
overlapping gill filaments
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

explain the countercurrent exchange system

A

blood in the filaments + water across it move in opposite directions
this maintains a steep concentration gradient for efficient diffusion so more gas exchange can occur

17
Q

what is the purpose of overlapping gill filaments?

A

increases resistance to the flow of ester

slows down flow of water over gills so more time for gas exchange

18
Q

give 4 adaptations of leaves for gas exchange

A

-large surface area exposed to environment
-irregularly shaped spongy mesophyll cells increase surface area for gas exchange
thin walls for quick gas exchange
gases move in + out of leaf through specialised pores (stomata)

19
Q

give the role of open stomata (turgid)

A

plants need to allow evaporation of water from leaves in order to maintain water uptake from soil

20
Q

give the role of closed stomata (flaccid)

A

plants need to conserve water when it is in short supply

21
Q

how do guard cells go from open to closed?

A

guard cells lose water due to losing potassium ions by active transport + become flaccid

22
Q

how do guard cells go from closed to open?

A

guard cells gain water due to potassium ions uptake + become turgid- this is due to the extra thickening on side of guard cell wall

23
Q

explain the role of lenticels

A

made up of loosely arranged cells with lots of air spaces that link the tissues so gas exchange can occur