exchange surfaces🦥 Flashcards
what is tidal volume
volume of air inhaled in one breath during regular breathing
why does a large mammal need a transport system
- high metabolic rate
- diffusion too slow as cant supply enough oxygen
- low sa:v ratio
- to prevent waste product build up
why is the delay between excitation of atria and ventricles important
- atria can fully contract
- atria can fully empty blood
- so ventricles do not contract too early
why is the excitation carried down the septum to the apex
- so that ventricle contraction starts at the bottom
- to push blood upwards
- for efficient emptying of ventricles
explain expiration
- 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
how does smoking cause smokers cough and how does smokers cough cause problems over time
- 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
how does good ventilation in alveoli create a steep concentration gradient
- 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
diseases that contribute to copd (chronic obstructive pulmonary disease)
emphysema
asthma
chronic bronchitis
how is a spirometer used to measure tidal volume
- 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
what effect does increased permeability of capillary walls have on surrounding tissues
- more tissue fluid
- increased pressure in tissue
- inflammation
- more white blood cells pass into tissues
- larger molecules pass into tissue fluid
smooth muscle function
constrict the airway
asthma reduces diameter of bronchiolew suggest how this happens
- smooth muscle contraction
- inflammation
- extra mucus production
why are capillaries and alveoli so close
- short diffusion distance
- steep concentration gradient
- high rate of diffusion
how does diaphragm/ intercostal muscles improve efficiency of gas exchange
- supply of o2
- removal of co2
why is expiration passive
muscles just relax
elastic fibres recoil
