Unit 11 - gas exchange in humans

Question 1

How does ventilation happen

Answer 1

1. the diaphragm, which is a sheet of muscle that separates the thorax from the abdomen.
2. the intercostal muscles which lie between the ribs

Question 2

process of inhalation

Answer 2

internal intercostal muscles relax and external intercostal muscles contract pulling your ribs up and out. diaphragm also contracts and flattens.
volume of thorax increases
air pressure in thorax decreases creating a negative pressure
air enters the lungs to equilibrate pressure

Question 3

process of exhalation

Answer 3

internal intercostal muscles contract and external intercostal muscles relax pulling your ribs down and in. diaphragm also relaxes and moves up.
volume of thorax decreases
air pressure in thorax increases creating a positive pressure
air exits the lungs to equilibrate pressure

Question 4

what is the trachea made from, and what is its purpose

Answer 4

made up of rings of cartilage, helps to keep trachea from collapsing

Question 5

pathway of oxygen

Answer 5

1. down the trachea
2. through left and right bronchus
3. through the bronchioles within each lung
4. alveoli is the site of gas exchange with the blood stream

Question 6

4 ways alveoli are specialised for maximising rate of diffusion

Answer 6

1. covered in capillaries, reducing diffusion distance
2. alveoli only 1 cell thick, reducing diffusion distance
3. large surface area in contact between capillaries and alveoli
4. blood is flowing through capillaries, maintaining concentration gradient

Question 7

what is the function of the larynx

Answer 7

a lid to stop your food going down your trachea when swallowing

Question 8

function of goblet cells

Answer 8

in the lung epithelium produce and secrete mucus

Question 9

function of mucus

Answer 9

traps bacteria, viruses and other particles that enter our lungs

Question 10

function of cilia

Answer 10

small hairs on the surface of epithelial cells, they push mucus and other small particles towards the nose and throat.

Question 11

effects of exercise on heart and lungs

Answer 11

1. rate of breathing increases and tidal volume
2. heart pumps faster.

Question 12

why does breathing and tidal volume increase with exercise

Answer 12

to maintain high concentrations of o2 and low co2 concentrations in alveoli

Question 13

name process inside the cells that produce co2

Answer 13

aerobic respiration

Question 14

effect on breathing of an increase of co2 concentration in the blood

Answer 14

rate of breathing increases

Question 15

how does the brain increase rate of breathing when there is a high co2 concentration in the blood

Answer 15

stimulus is co2, ph of the blood decreases. co2/ph detected by the brain by a receptor. brain sends impulses to the intercostal muscles and diaphragm so they contract more.

Question 16

how do oxygen molecules move from the alveoli into the blood

Answer 16

diffusions across cell membranes high concentration to low concentration of o2 down gradient.