mammalian gaseous exchange and structure

Question 1

what is alveoli

Answer 1

tiny fold of lung epithelium which increase sa

Question 2

what is a diaphragm

Answer 2

layer of muscle beneath lungs

Question 3

what are the intercostal muscles

Answer 3

muscles between the ribs.

Question 4

what is ventilation

Answer 4

refreshing of air in the lungs, so there is a high o2 concentration and low co2 conc in blood.

Question 5

what are lungs

Answer 5

inflatable sacs lying in the chest cavity

Question 6

what structures does air pass through before getting to the lung

Answer 6

nose or mouth cavity
trachea
bronchi
bronchioles
alveoli- tiny air filled sacs.

Question 7

what two muscles help produce breathing movements

Answer 7

intercostal muscles
diaphragm

Question 8

what process allows gases to pass into the alveoli

Answer 8

diffusion

Question 9

describe the gaseous exchange which occurs in the alveoli

Answer 9

o2 from air in alveoli passes into the blood in capillaries.
co2 passes from blood in capillaries to air in alveoli.

Question 10

what is the size of alveoli

Answer 10

100-300 micrometres

Question 11

what is the function of alveoli

Answer 11

facilitate gas exchange between oxygen in the alveoli and carbon dioxide in the capillary blood

Question 12

why is it benefical for gas exchange that capillaries are narrow

Answer 12

because the erythrocytes are squeezed against the capillary wall. making erythrocytes are closer to the air in the alveoli and reducing diffusion distance

Question 13

how thick are alveolus and capillary walls

Answer 13

1 cell thick

Question 14

what is the surfactant and what is its function

Answer 14

a thin layer of moisture which lines the inner walls of alveoli, it reduces cohesive forces between water molecules as cohesive forces can cause alveoli to collapse.

Question 15

what are the factors which reduce diffusion distance between alveoli and capillaries

Answer 15

1 cell thick walls
alveoli are in close contact to capilaries
narrow capillaries forcing erythrocytes to squeeze.
walls of capillary and alveoli are made of squamous cells(thin and flat).

Question 16

how is a steep concentration gradient maintained between alveoli and capillaries

Answer 16

good blood supply
blood system transports co2 from tissue to lungs to always ensure co2 in blood is higher than co2 in air in alveoli.
vice versa for 02, blood transport o2 away so conc of o2 in alveoli is higher than in blood

Question 17

where is o2 always higher, alveoli or capillaru

Answer 17

alveoli

Question 18

what does ventilation ensure

Answer 18

concentration of o2 in alveoli remains higher than in capillary

concentration of co2 in capillary remains higher than in alveoli

Question 19

what happens to the diaphragm during inspiration and expiration

Answer 19

inspiration- moves down

expiration- relaxes and is pushed up

Question 20

what happens with intercostal muscles during inspiration and expiration

Answer 20

inspiration- contract, raise ribs

expiration- relax, ribs lower.

Question 21

when do internal intercostal muscles contract

Answer 21

during forced expiration- coughing or exercise

Question 22

when does the chest cavity increase

Answer 22

during inspiration

Question 23

when does the chest cavity decrease in volume

Answer 23

expiration

Question 24

what happens to pressure in chest cavity during inspiration and expiration

Answer 24

inspiration- drops below atmospheric/ environmental pressure

expiration- environmental/ atmospheric pressure is higher

Question 25

describe inspiration

Answer 25

air moved into lungs,
intercostal muscles contract, ribs raise and diaphragm lowers.
chest cavity volume increases and pressure decreases below atmospheric pressure.

Question 26

Describe expiration

Answer 26

Diaphragm relaxes
Intercostal muscles relax
Ribs lower
Volume of chest cavity decreases and pressure increases.