mammalian gas exchange system

Question 1

what is the route that air takes during ventilation

Answer 1

trachea –> bronchi –> bronchioles –> alveoli

Question 2

how is the trachea adapted for its functions

Answer 2

has rings of cartilage –> support, ensure it does not collapse when pressure inside decrease

on the side where oesophagus touch trachea, no cartilage –> oesophagus contract and relax when moving food to stomach

lined with ciliated epithelium with goblet cells –> release mucus to trap dust and pathogens, mucus gets removed by coughing by ciliated epithelium cells

smooth muscle in walls –> contract when there are harmful substances –> lumen constricting, reducing airflow into lungs / relax –> lumen dilates || stretch and recoil of lumen is due to elastic fibres in tracheal wall

Question 3

how are the bronchi and bronchioles adapted

Answer 3

bronchi connect to right and left lung
bronchi spilt into smaller tubes to create a network of bronchioles

have cartilage within their walls –> structural support + keep tubes open

Question 4

how is the alveoli adapted for its functions

Answer 4

located at the end of bronchioles
site of gas exchange
oxygen diffuses from alveoli into blood in capillaries
carbon dioxide diffuses from the blood in the capillaries to alveoli

tiny air sacs
large number –> large surface area for gas exchange [diffusion]

walls are thin, squamous epithelial cells –> short diffusion distance

surrounded by a network of capillaries –> remove exchanged gases, maintain concentration gradient

Question 5

adaptation of nasal cavity

Answer 5

large surface area and good blood supply –> warms the air as it passes into the body

hairy lining –> traps dust and bacteria in mucus and prevent them from reaching lungs, could cause infection

moist surfaces –> increases the humidity of the incoming air this reduces the evaporation of water in lungs

Question 6

function of cartilage

Answer 6

holds airways open

Question 7

function of smooth muscle

Answer 7

contracts/relaxes to regulate airway size

Question 8

function of elastic fibres

Answer 8

elastic recoil of airways

Question 9

function of goblet cells

Answer 9

secrete mucus

Question 10

function of ciliated epithelium

Answer 10

move mucus up throat