exchange surfaces🦥

Question 1

what is tidal volume

Answer 1

volume of air inhaled in one breath during regular breathing

Question 2

why does a large mammal need a transport system

Answer 2

• high metabolic rate
• diffusion too slow as cant supply enough oxygen
• low sa:v ratio
• to prevent waste product build up

Question 3

why is the delay between excitation of atria and ventricles important

Answer 3

• atria can fully contract
• atria can fully empty blood
• so ventricles do not contract too early

Question 4

why is the excitation carried down the septum to the apex

Answer 4

• so that ventricle contraction starts at the bottom
• to push blood upwards
• for efficient emptying of ventricles

Question 5

explain expiration

Answer 5

• intercoastal muscles/diaphragm relax
• diaphragm moves up
• volume of thorax decreases
• pressure of thorax increases to above atmospheric pressure
• air leaves down pressure gradient
• elastic fibres in alveoli recoil

Question 6

how does smoking cause smokers cough and how does smokers cough cause problems over time

Answer 6

• tar
• cigarette smoke damages cilia
• cigarette smoke stimulates goblet cells to release more mucus
• mucus builds up and traps more pathogens

-cough is an attempt to increase air flow by removing mucus

• coughing damages alveoli
• coughing causes formation of scar tissue
• coughing causes airway walls to thicken
• coughing causes lumen of airways to narrow
• flow of air restricted

Question 7

how does good ventilation in alveoli create a steep concentration gradient

Answer 7

• increases partial pressure/ concentration of oxygen in alveoli
• so comcentration of oxygen is higher in alveoli than blood
• decreases partial pressure/ comcentration of carbon dioxide in alveoli
• so concentration of carbon dioxide is lower in alveoli than in blood

Question 8

diseases that contribute to copd (chronic obstructive pulmonary disease)

Answer 8

emphysema
asthma
chronic bronchitis

Question 9

how is a spirometer used to measure tidal volume

Answer 9

• not breathing through nose
• subject breathes normally
• measure height of waves from trace
• as breathe in the lid goes down, as breathe out the lid goes up
• movement of lid recorded

Question 10

what effect does increased permeability of capillary walls have on surrounding tissues

Answer 10

• more tissue fluid
• increased pressure in tissue
• inflammation
• more white blood cells pass into tissues
• larger molecules pass into tissue fluid

Question 11

smooth muscle function

Answer 11

constrict the airway

Question 12

asthma reduces diameter of bronchiolew suggest how this happens

Answer 12

• smooth muscle contraction
• inflammation
• extra mucus production

Question 13

why are capillaries and alveoli so close

Answer 13

• short diffusion distance
• steep concentration gradient
• high rate of diffusion

Question 14

how does diaphragm/ intercostal muscles improve efficiency of gas exchange

Answer 14

• supply of o2

- removal of co2

Question 15

why is expiration passive

Answer 15

muscles just relax

elastic fibres recoil

Question 16

allergens can cause smooth muscle to contract, how does this affect ventilation

Answer 16

• reduction in diameter of bronchi

- harder to inhale and exhale

Question 17

after expiration where is rib cage

Answer 17

low position

Question 18

cartilage function

Answer 18

supports trachea to prevent collapse

Question 19

structural features of bronchioles

Answer 19

• no goblet cells
• elastic fibres
• cartilage in larger bronchioles