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Biology > 4. Gas exchange > Flashcards

4. Gas exchange Flashcards

1
Q

Why does the volume of an organism affect the rate of gas production/use

A

Bigger volume = more cells
Increase use of oxygen and production of carbon dioxide

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2
Q

Why do some animals need a higher metabolic rate than others

A

Smaller mammals and birds have a larger SA:V so lose heat faster. They need a higher metabolic rate so respire faster

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3
Q

What is aerobic respiration

A

Glucose + Oxygen -> Carbon dioxide + water + ATP

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4
Q

How do gases exchange over surfaces for aerobic respiration

A

Diffusion

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5
Q

How do single celled organisms gas exchange

A

Simple diffusion of gases across their outer surface membrane.
Large SA:V and short diffusion pathway so rates can be achived.
Continuous aerobic respiration will maintain concentration gradients for O2 and CO2

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6
Q

What stuructures do fish use to gas exchange

A

The gills
Between the buccal cavity and the operculum

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7
Q

How is the surface area of the gill alow for effiecient gas exchange

A

Each gill contains many filaments each covered in many lamellae. Give a large SA for diffusion

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8
Q

How are a fishs gill diffusion pathway structured for efficient gas exchange

A

Gills have rich blood supply
Many capillaries in a single layer of thin epithelium
Close to thin-walled lamellae
Many cappilaries increase SA
Thin epithelium ensures short diffusion pathway between blood and water

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9
Q

How is a concentration gradient maintained in a fish’s gill

A
  • Continous flow of blood through capillaries ensures frsh oxygenated blood is quickly removed from gills and replaced with deoxygenated blood
  • Water flows over the gill plates in the opposite direction to the flow of blood in capillaires. = Counter current mechanis
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10
Q

Why is the counter current mechanism an improvment over parallel flow

A

Gas exchange takes place across the entire gill
Oxygen never reaches equilibrium
Blood always meets with water with higher concentration of O2 so conc gradient is maintained along whole length of lamellae
Constant diffusion can occur

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11
Q

What does a ventilation mechanism do in a fish

A

Ensures water enters the fishs mouth and flows over the gills, leaving via operculum
Constant flow of water over the gills

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12
Q

What is the fructure of an insects body

A

Protected by an exoskeleton made of chitin - prevents insects using their bodies surface for diffusion
Outermost layer is waxy and waterproof which minimises water loss
Tracheal system constists of air-filled tubes (tracheae) that open to the outside through small holes in exoskelenton called spiricales

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13
Q

What is the trachea system

A

Larger tracheal tubes subdivide into smaller tubes that penetrate into and between cells.
Finer tubes are tracheoles - site of gas exchange
Large number of them gives large SA for diffusion and short diffusion pathway

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14
Q

How do insects repire at resting

A

Rely on diffusion down a concentration gradient taht is maintained int the tracheal system due to cellular repsiration in the insects tissues

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15
Q

How does an insects respiration change during flight

A

Require more ATP to fly
Increase in O2 needed
Ventillation by contraction of the abb muscles force air in and out of spiricles and tracheae to maintain greater airfoe
Maintain steeper conc gradients for fast diffusion
Abdominal pumping

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16
Q

How are insects adapted to minimise water loss

A

-Waterproof waxy cuticle
-Spiricles guraded by valves which can close spiricles
-Spiricles surrounded by hairs which trap a layer of moist air

17
Q

Where does gas excange occur in a plant

A

Spongy mesophyll layer of leaf
Large air spaces and thin-walled cells -Large SA and short diff pathway
In close contact with numerous stomata which gases enter and leave via diffusion down a steep concentration gradient

18
Q

Why will there be a steep concentration gradient for gases in a plant

A

CO2 will be low in the day as its used in photosynthesis.
The reverse for oxygen
O2 conc low at night as its used in repsiration
Reverse for CO2

19
Q

How is a short diffusion pathway maintained in a plant

A

The spongy mesophyl cells have thin cell walls and being in direct contact with air.
Leaf is a thin structure

20
Q

How does a leaf minimise water loss while still maintaining effective diffusion

A

Stomata mainly on underside of leaf
Thicker waxy cuticle on upper eppidermis
Guard cells can close stomata

21
Q

Why do humans need gas exchange

A

Need a constant supply of oxygen to release energy in the form of ATP duiring respiration.
We need to remove CO2 or it would lower the pH

22
Q

Why is the volume of gases needed to exchange larger in mammals

A

High rate of respiration as they need to maintain a constant body tempertaure

23
Q

What is the structure of the gas exchange system in humans

A

Lungs situated on either side of the heart in the thorax.
Surrounded by ribs and with the diaphragm at the base
Allows gaseous exchange between air in lungs and blood in cappilaries

24
Q

Where does air move through in humans

A

Nose/mouth -> trachea -> bronchi -> bronchioles -> alveoli

25
Q

What do airways contain

A

Mucus membranes containing goblet cells which secrete mucus and are lined with a ciliated epithelium.
mucus- traps micro-organisms and debris
-Cilia - move micro-organisms and dust particles allong with the mucus

26
Q

Where does gas exchange take place in humans

A

Alveoli and capillaries.
O2 diffuses through epithelium of alveoli and the endothelium of the capillairies into the blood
Combines with heamoglobin

27
Q

How do alveoli enable a maximum rate of diffusion

A

Provide a large SA - there are millions of alveoli
Have thin exchange surface - only 2 layers of cell to diffuse across
Large conc gradient -Blood continously circulated and ventilation ensures the right molecules are being taken in and out

28
Q

What does breathing invlove

A

Inspiration
Expiration
Both require movements to alter volume of thorax
Creates air pressure difference between thorax and atmosphere
Thorax is airtight so air is drawn in when thorax pressure is lower than atmospheric. Vise versa

29
Q

How does air move

A

from an area of higher pressure to one of lower pressure down a pressure gradient.

30
Q

How do pressure and volume relate in the lungs

A

Inversely proportional

31
Q

What is the ventillation mechanism in the lungs

A

Movements of the ribcage, the diaphragm and the internal and external intercostal muscles. The muscles are anatgonistic - one contracts whilsts one stretch

32
Q

how does the intercostal muscles and diaphragm muscles bring about inspiration

A
  • External intercostal muscles contract
    -Ribcage moves up and out
  • Diaphragm muscles contract and diapraghm flattens
    -Elastic tissue stretches
    -Thorax volume increase
    -Pressure decreases below atmospheric
    -Air enters down a pressure gradient
33
Q

how does the intercostal muscles and diaphragm muscles bring about expiration at rest

A
  • External intercostal muscles relax
    -Ribcage moves down and in
    -Diaphragm muscles relax and returns to dome shape
    -Elastic tissue recoils
    Vol of thorax decreases
    -pressure increases above atmospheric
    -Air forced out down a pressure gradient
34
Q

What happens in forced expiration

A

Same as normal expiration except external intercostal muscles realx and the internal intercostal muscles contract
This pulls the ribcage futher down and in

35
Q

What is the role of elastic tissue in breathing

A

Walls of alveoli contain elastin
During inspiration the elastic tissue in the the lungs stretches to allow the lungs to inflate
During expiration the elastic tissue recoils

36
Q

What is tidal volume

A

The volume of air breathed in or out of the lungs in a normal resting breath

37
Q

What is ventilation rate

A

The number of breathes in and out per min

38
Q

What is pulomonary ventillation

A

The total volume of air that is moved into the lungs in one min
PV = TV x VR

39
Q

How do correlation and causation link

A

a correlation between two variables does not mean the variables are linked. Any correlation observed between two variables could just be a coincidence, and an extraneous factor may be responsible for causing the changes

Biology (23 decks)

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