Theme 4 Part 3 Gas Exchange

Question 1

Why is gas exchanged needed

Answer 1

Needed for the Krebs cycle and oxidative phosphorylation (which consumes oxygen and makes co2)

Photosynthesis (which consumes co2 and makes oxygen)

Ph regulation (through co2 regulations which forms carbonic acid)

Question 2

Red cells is
Blue cells is

Answer 2

Oxygenated
Deoxygenated blood

Question 3

Where does co2 move
Where does oxygen move

Answer 3

Out of the cells and into the blood
Out of the blood and into the cells then back to heart

So oxygen and nuterients go to the cells
And co2 and waste goes into the blood

Question 4

What are the broken down steps of respiration

Answer 4

1. Ventilation by bulk flow
2. Diffusion across the respiratory surface
3. Circulation by bulk flow
4. Diffusion between blood and cells

Question 5

What happens in ventilation by bulk flow

Answer 5

Breathing to move oxygen into the lungs then co2 out

Question 6

What happens in the smaller scale of Diffusion across the respiratory surface

Answer 6

Oxygen diffuses from the lung into the blood , the oxygenated blood goes back to the heart

Co2 goes out of blood into the lungs

This is when you breathe in

Question 7

What happens in the smaller scale of circulation by bulk flow

Answer 7

The oxygenated blood and co2 is moving through the circulatory system through out the body

Also called perfusion (moving fluid throughout the body)

Question 8

What happens in the smaller scale of diffusion between blood and cells

Answer 8

the oxygen in the blood now diffuses into the cells and

co2 diffuses out of the cells and into the blood

Now that blood goes back to the heart

Question 9

How does drawing air into human lungs work

What about animals

Answer 9

By negative pressure breathing

Lowering diaphragm when breathing in causes inward bulk flow of air

They use positive pressure breathing

Question 10

What is the respiratory medium
The gas exchange surface

Answer 10

Air/water

Body surface, lungs, gills, etc.

Question 11

Diffusion of blood to cells and co2 to blood is

Answer 11

Slow

Question 12

Gas exchange helps with…

Answer 12

The low diffusion rate of blood and co2 when breathing

It’s the diffusion between the environment (air/water) and the extracellular fluid in the body

Question 13

Why are the lungs internalized

Answer 13

To prevent evaporative water loss during gas exchange

Question 14

The surface area of the gas exchange surface is proportional to _____

What does this mean for large animals

Answer 14

The mass and metabolic rate of the organism

Smaller animals smaller gas exhance surface

Larger animals need specialized gas exchange structures to support their metabolic needs (lungs,gills,trachea)

not just the body surface would suffice since the area doesn’t increase

Question 15

Animals with high metabolic rate have

Answer 15

Higher area of gas exchange surface
Opposite for animals with low metabolic rate

But for each as mass increases areas of gas exchange surface increases

Question 16

How do fish extend the surface area of the gas exhange surface

Answer 16

By having gills that extend to pass flow

Have lamellae that extend outward like pages of a book and water passes over each sheet

This increases the SA that diffusion can happen against

Question 17

How do terrestrial animals extend the surface area of the gas exhange surface

Answer 17

They have tracheoles (tube that let air pass through) which extend out to the surface of the body.

Then every cell is in contact with the tracheole

Bring external environment in

Question 18

How do mammals extend the surface area of the gas exhange surface

Answer 18

They have internalized lungs that bring air go from large trachea

bringing air in then trachea splits into very small branches that lead to tiny thin alveoli (still in lungs) multiplied the SA since so many alveoli

Question 19

What is ficks law of diffusion

Answer 19

Rate= D A (dC/dX)

D= diffusion coefficient
A= gas exchange area
Dc/dx= the partial pressure of oxygen being diffused/ the dstance (thickness)

If dx increases (alveoli get thicker) then diffusion rate decreases

Question 20

What is the characteristic of the gas exhange structure

How does this relate to fick law

Answer 20

Has a large SA to support high rates of diffusion (ex alveoli increase A but reduce delta x)

It’s moist so that the gasses can dissolve through them

Question 21

What does the heart do in terms on extracellular fluid

Answer 21

Has a series of vessels which transport the fluid around the body of the animal

Question 22

What happens at the ECF cell interface for gas exchange

Answer 22

Diffusion occurs at the capillaries which are really small in diameter, thin, but high SA

So more area for exchange of oxygen and co2

Question 23

How does air and elevation affect gas exchange

Answer 23

The partial pressure of oxygen changes with elevation

At low elevation the pressure of air is higher so partial pressure of oxygen is too

At higher elevation the pressure of air is lower so partial pressure of oxygen is too

Question 24

What are partial pressure gradients

What happens if lower pressure

Answer 24

Diffusion is based on these

dC in ficks law

Gradient of what’s in the cell and what’s out the cell

Lower pressure, lower dC (partial pressure gradient. so diffusion rate decreases (numerator is smaller)

Question 25

What are the three patterns of gas exchange

Answer 25

Countercurrent
Crosscurrent
Uniform pool

Question 26

What happens in uniform pool exchange

Answer 26

Happens in mammalian lungs

“Tidal pressure”

Air move from nose to trachea to lungs to alveoli bidirectionally (so it can go in and out)

Then deoxygenated blood in the vessels from the heart interacts with the alveoli at the lungs picks up oxygen

Then oxygenated blood goes back to the heart

Question 27

What happens in cross current gas exchange

Answer 27

Seen in avian lungs, birds

Air moves unidirectionally through gas exchange surface (doesn’t move in and out) the blood move perpendicular to to lungs (cross)

Take 4 inhale exhale cycles for 1 unit of air to move through lungs

Have posterior and anterior air sac that are reservoirs on either side of where gas exchange occurs

In the first inhale air goes to the posterior air sac of the lung then moves over to the anterior air sac

As it exhales it drives air forward from the posterior air sac across the peribrachea

This inhale exhale happens again to maximize uptake of oxygen using the reservoirs

Question 28

What is counter current exchange

Answer 28

Occurs in fish gills

Less oxygen available in water , moving water across respiratory surface is harder in water, so these animals have lower metabolic rates

Water move across fish gills unidirectionally

Blood moves across the gill in the opposite direction

If In same direction, water with oxygen decreases amount of oxygen left in the water because oxygen diffuses into the blood.

If blood moves in same direction, low oxygen in blood and high oxygen in water initially. So delta c is very high at one end and not the other

Counter current keeps the gradient maintained, delta c all throughout

Question 29

Why does counter current exchange happen

Answer 29

If In same direction, water with oxygen decreases amount of oxygen left in the water because that oxygen diffuses into the blood.

If blood moves in same direction, low oxygen in blood and high oxygen in water initially. So delta c is very high at one end and not the other

Counter current keeps the gradient maintained, delta c (pressure of oxygen). all throughout gill is steady

Question 30

How is counter current gas exchange helpful

Answer 30

Since oxygen is less available in water, through counter current they can conserve the amount of oxygen left in the water for them to use

Able to draw 85% of oxygen from water

Question 31

What is the order of efficiency of gas exchange

Answer 31

Fish (85%)
Birds (in middle)
Mammals (25%)

Question 32

How is countercurrent exchange used for heat retention

Answer 32

Maintaining steady gradient of cold and hot

Warm blood move out toward the limbs and gets colder

Cold blood moves to the heart to get warmer

The veins and arteries are closer together and opposite directions to transfer heat and cold to the blood in each other