Gas exchange 👍

Question 1

Describe type I pneumocytes

Answer 1

• Cover 70% of the internal surface area of each alvelous.
• Thin, flattened epithelial cells.
• Amitotic and unable to replicate
• Connected by occluding junctions which prevent leakage

Question 2

What is the function and adaptations of type I pneumocytes

Answer 2

Gas exchange. They’re extremely thin to make them:
1. More permeable
2. Shorter diffusion distance

Question 3

What is the route of air during ventilation?

Answer 3

Nose/mouth
Nasal cavity
Larynx
Epiglottis
Trachea
Bronchi
Bronchioles
Alveoli

Question 4

Process of inspiration regarding body/organs

Answer 4

As you inhale the external intercostal muscles contract (internal intercostal relax) which causes the ribcage to move up and out, and the diaphragm flattens downward. Abdominal muscles relax. Through the expansion the pressure decreases and the volume increases. Decrease in pressure causes the air to flow in, causing the lungs to inflate and gas exchange to happen in the alveoli.

Question 5

Process of expiration regarding body/organs

Answer 5

The internal intercostal muscles contract and the external intercostal muscles relax, causing ribcage to move down and inwards. Abdominal muscles contract, pushing diaphragm up. Pressure increases, volume decreases, air is forced out.

Question 6

Describe type II pneumocytes

Answer 6

Dense, large cells (cuboidal or round) full of surfactant concentrated in the alveoli septum.

Question 7

Diffusion

Answer 7

Movement of gas from high to low concentration gradient (down conc. grad.) which makes ventilation like actually useful

Question 7

Function of type II pneumocytes

Answer 7

Secrete surfactant on inner surface of alveolus for moisture to:
1. Aid diffusion of gases
2. Prevent walls from sticking together and thus collapsing
They also
* Divide to form type I pneumocytes in case of damage to epithelium

Question 8

What happens in emphysema

Answer 8

Tobacco gets into lungs. Leukocytes release elastase which breaks down the connective tissue - protein elastin - in lungs. Loses lung elasticity in alveoli and in bronchiol causes collapse as they are not turgid anymore. When person inhales again, the air going in causes the already air-filled alveoli to forcefully expand, destroying the alveolar membrane (gas exchange medium). Large air pockets in lungs.

Question 8

Define emphysema

Answer 8

Disease which causes inflammation of alveoli. Affects area to volume ratio.

Question 9

Emphysema treatment

Answer 9

Stop smoking lmao. Oxygen therapies. Bronchodilators.

Question 10

Spirometer

Answer 10

Instrument to measure volume of air entering and leaving lungs

Question 11

Tidal volume

Answer 11

Volume of air inspired or expired in a single breath during regular breathing

Question 12

Explain process of gas exchange in alveoli

Answer 12

1. Oxygen diffuses into blood, carbon dioxide diffuses out of blood.
2. Air in the alveolus is higher in Oxygen.
3. This causes a concentration gradient which provokes diffusion.
4. Concentration gradient is maintained by blood flow.
5. Large surface area created by many alveoli for more efficient diffusion
6. Rich supply of capillaries allows efficient exchange.
7. Type I pneumocytes thin, more permeable, which makes diffusion faster.

Question 13

What does surfactant do

Answer 13

• Reduces surface tension which prevents walls from sticking together and collapsing
• Allows more efficient gas exchange by providing medium
  + kills or prohibits dissemination of pathogens

Question 14

Trachea adaptations

Answer 14

• Rings of cartilage which help support its shape (stays open but still flexible)
• strengthened by cartilage
• layer of smooth muscle that contracts or relaxes to change diameter of airway
• lined with ciliated epithelium to remove particles trapped in mucus that entered airway (bronchi too)

Question 15

adaptations of mammalian lungs

Answer 15

1. Alveoli (lots) have large surface area to ensure efficient gas exchange.
2. Bronchioles ensure even distribution of alveoli throughout lungs
3. Alveoli surrounded by clusters of capillary beds, increased surface area for diffusion of gas - maintains concentration gradient.
4. Surfactant lowers surface tension

Question 16

where are stomata mostly found

Answer 16

lower epidermis

Question 17

What does potometer measure?

Answer 17

Rate of water uptake by a plant

Question 18

How does bubble potometer work?

Answer 18

Measures movement of air bubble along a water-filled tube as water is drawn up by the shoot as plant transpirates

Question 19

How does mass potometer work?

Answer 19

Measures loss of mass of water in water-filled tube as plant draws it up and transpirates

Question 20

What does humidity do to transpiration?

Answer 20

As humidity increases, transpiration decreases. Air outside of leaf is saturated with water molecules: there is no concentration gradient. Equilibrium may be reached as levels of water vapour inside/outside are the same, net loss of water is zero.

Question 21

What does temperature do to transpiration?

Answer 21

As temperature increases, transpiration increases until it DROPS. Higher temperature elevates kinetic energy of particles, making them evaporate quicker. Eventually, stomata close to prevent excess water loss, causing a dramatic drop in transpiration rate.

Question 22

What does air movement do to transpiration?

Answer 22

As air movement increases, transpiration increases. Still air causes bundles of water vapour to form around stomata, meaning no concentration gradient. Air movement takes those bundles away, causing concentration gradient to go up and transpiration to increase.

Question 23

What does light do to transpiration?

Answer 23

As light increases, transpiration increases until it PLATEAUS. Stomata closed in darkness because no photosynthesis. When it starts to get lighter transpiration rate stars to increase, until eventually it plateaus. After certain point, increasing light has no effect on transpiration rate.

Question 24

What set of conditions would cause transpiration to go at slowest rate?

Answer 24

HIGH humidity
LOW temperature
LOW air movement
LOW light

Question 25

Advantages of transpiration.

Answer 25

• Means of cooling through evaporation
• Transpiration stream helpful in uptake of mineral ions
• Turgor pressure of cells provides support to leaves.

Question 26

What is the type of blood flow in fish?

Answer 26

Countercurrent.

Question 27

In healthy lungs, a concentration gradient is maintained between the alveoli and the lung capillaries. Describe and explain how this is maintained.

Answer 27

Ventilation brings in air from the outside with a higher oxygen concentration.
Circulation allows for it to be maintained and removes highly oxygenated blood from lungs.

Question 28

Define transipiration

Answer 28

The loss of water vapour from the leaves of plants during photosynthesis

Question 29

Why would a student dry off the leaves of a plant in a potometer experiment

Answer 29

To ensure no water molecules are blocking the stomata or affecting transpiration rate

Question 30

What are two precautions a student should take when setting up a potometer to ensure reliable results

Answer 30

Make sure the joints are airtight and sealed.
Restart the air bubble to start position for each experiment.
Ensure no air bubbles present.
Close the taps.
Cut the shoot at a slant. Cut the plant underwater to avoid air molecule going into xylem.
Construct the potometer underwater to prevent airbubbles from getting trapped.