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A level Biology > Ventilation + gas exchange in the lungs > Flashcards

Ventilation + gas exchange in the lungs Flashcards

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1
Q

Inspiration

A

Breathing in

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2
Q

What is ventilation

A

The movement of air in and out of lungs (breathing)

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3
Q

Expiration

A

Breathing out

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4
Q

What controls ventilation

A

Movement of muscles:
The diaphragm
The external intercostal muscles
(The internal intercostal muscles in forced expiration)

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5
Q

Inspiration: movement of muscles

A

The diaphragm contacts and flattens (moving downwards)
The external intercostal muscles contract, moving the rib cage upwards and outwards

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6
Q

Inspiration: effect of thoracic cavity volume

A

It increases
INspiration INcrease in thoracic cavity volume

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7
Q

Effect of increasing thoracic cavity volume

A

The pressure of gases inside the thoracic cavity decreases, below atmospheric pressure

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8
Q

How does air move into the lungs in inspiration?

A

Down a PRESSURE gradient from the trachea forced into the thoracic cavity and lungs

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9
Q

What do internal intercostal muscles do in inspiration?

A

Remain RELAXED

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10
Q

Is inspiration an active process?

A

Yes: requires energy for diaphragm and external intercostal muscles to CONTRACT

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11
Q

Expiration: movement of muscles

A

The diaphragm relaxes and curves by pulling upwards
The external intercostal muscles relax causing the rib cage to move downwards and inwards

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12
Q

Expiration: effect on thoracic cavity volume

A

Decreases due to movement of muscles moving in

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13
Q

Effect of decreasing thoracic cavity volume in expiration?

A

The pressure of gases increase inside the thoracic cavity above atmospheric pressure

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14
Q

How does air move out the lungs in expiration?

A

The air pressure inside the lungs has increased above atmospheric pressure so air moves out down a PRESSURE gradient from lungs to trachea out through mouth

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15
Q

What do internal intercostal muscles do in NORMAL expiration?

A

Still relaxed

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16
Q

Is normal expiration a passive process?

A

Yes because requires no contraction of muscles

17
Q

Forced expiration

A

When you breathe out all the air you can from your lungs

18
Q

Forced expiration muscle movement

A

The diaphragm and external intercostal muscles are relaxed again to decrease thoracic cavity
But internal intercostal muscles will contract to decrease thoracic cavity even more by moving rib cage further in to force more air out

19
Q

Movement of internal and external intercostal muscles in forced expiration

A

Internal = contracts
External = relaxed
So ANTAGONISTIC

20
Q

Where is the site of gas exchange in the lungs?

A

Alveoli:

21
Q

What are alveoli?

A

Millions of microscopic air sacks contacted to the bronchioles

22
Q

Movement of gases in alveoli?

A

Oxygen from the alveoli into the blood (oxygenates blood(
Carbon dioxide from the deoxygenated blood into the alveoli out the body

23
Q

Structure of alveoli

A

Alveolar epithelium around the air space = thin layer of flat cells for a short diffusion distance
Connected to capillary endothelium (wall) of thin layer of flat cells
Elastin to help it recoil after movement of gases

24
Q

Oxygen in alveoli

A

Diffuses into blood from alveoli across 2 layers: first the alveolar epithelium then capillary endothelium

25
Q

Carbon dioxide in alveoli

A

Diffuses out of the blood into the alveoli: first the capillary endothelium then alveolar epithelium

26
Q

How do gases move in the alveoli

A

Down their concentration gradient not pressure

27
Q

Route of oxygen summary

A

Trachea
Bronchi
Bronchioles
Alveoli
Alveolar epithelium
Capillary endothelium
Blood

28
Q

Route of carbon dioxide summary

A

Blood
Capillary endothelium
Alveolar epithelium
Alveoli
Bronchiole
Bronchi
Trachea

29
Q

Factors affecting rate of diffusion of gases in the alveoli

A

Thin exchange surface
A large surface area
A steep concentration gradient

30
Q

Thin exchange surface area: alveoli

A

Because both the alveolar epithelium and capillary endothelium are 1 cell thick

31
Q

A large surface area: alveoli

A

Millions of alveoli (large surface area for exchange)

32
Q

A steep concentration gradient: alveoli

A

Of oxygen and carbon dioxide: maintained by the flow of blood in capillaries to remove O2 rich blood (more diffuses in) and supplies CO2 rich blood (more diffuses out)
Ventilation to supply more O2 and remove CO2

A level Biology (60 decks)

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