B11 ~ gas exchange in humans
the lungs:
enters through bronchi forming network of bronchioles
surrounded by cartilage to support the tubes to keep them open
travels down trachea to lungs
goblet cells on the lining
lined by goblet cells
secretes mucus to trap microorganisms and dust particles
lined by cilia hairs on the surface of ciliated cells to sweep the mucus up from the lungs and up trachea to the mouth to be swallowed to the stomach
end of bronchioles are air sacs with bulges of alveoli
alveoli covered in tiny blood capillaries for oxygen and carbon dioxide exchanged between blood and air. the movement of air is called ventilation
Alveoli adaptations:
thin permeable walls so diffusion doesn't have to travel as far
moist lining: the gasses dissolve before they diffuse
large surface area for diffusion
high concentration gradients as blood flowing past the air sacs and ventilation of the lungs
bands of cartilage surround trachea and bronchi to support the tubes and keep them open during breathing as they might collapse when pressure decreases.
breathing:
out
in
diaphragm: contracts
external intercostal muscles: contract
rips move: upwards and outward
air pressure: decrease
diaphragm: relaxes
air pressure: increase
external intercostal muscles: relax
ribs move: drop back down pressing against lungs
breathing rate:
pH:
as physical activity increases the rate/depth of breathing increase as muscles contract faster as they respire faster so make more co2 quicker which is acidic gas which dissolve easily in water based solutions: cytoplasm and blood plasma. this increase the acidity of the solution which will effect activity of cell enzymes so needs to be removed quickly. the body detects the increase of co2 by the receptors which sends an impulse to diaphragm and intercoastal muscles to increase rate/depth of breathing to removing co2 quicker.