Human Flashcards
Why are there rings of cartilage in the trachea
Prevents trachea from collapsing as air pressure falls
What do cillia do
Move dirt laden mucus towards throat
What do goblet cells do
Secrete mucus to trap dirt particles
What is the function of the muscles in the bronchioles
Allows them to constrict so they can control the flow of air in and out of the alveoli
Why are there elastic fibres between the alveoli
Allow them to stretch as they fill with air and spring back during breathing out to expel co2
Describe process of inhalation
Diaphragm contracts
External intercostal muscles contract, internal intercostal muscle relax
Rib cage moves up and out so volume of thoracic cavity increases amd pressure is reduced
Air moves into trachea down the pressure gradient
Active process- requires energy
Describe process of exhalation
Diaphragm relaxes
External intercostal muscles relax , rib cage moves in and down
Volume of thoracic cavity decreases which increases air pressure
Air moves out of the trachea down the pressure gradient
Normal expiration (not forced) is a passive process
Journey of air
Trachea, bronchi, bronchioles, alveoli, alveolar epithelium, capillary endothelium, blood
Adaptions
Cartilage
In trachea and bronchus
Provides strength and holds airway open when air pressure falls
Adaption
Surfactant
Coats surface of lungs
Phospholipid layer which maintains moisture and reduces surface tension to stop alveoli collapsing when air pressure falls
Adaptions
Muscle
Smooth muscle lining trachea to bronchioles
Contract to constrict airways
Adaptions
Goblet cells
Line from trachea to bronchioles
Secrete mucus that traps dust and bacteria breathed into the lungs
Adaptions
Ciliated epithelial cells
Lining trachea to bronchioles
Move mucus up airways helps keep airways clear and prevent infection
Contain lots of mitochondria to provide energy required to move them
Adaptions
Elastin
Lining of all airways and alveoli
Allow lung tissue to stretch and recoil and alveoli to return to shape after exhaling
Adaptions
Squamous epithelium
Lining alveoli
Gives short diffusion path only 0.05-0.3 micrometers wide
Ventilation
Involves inhalation and exhalation
Why do larger organisms need specialised surface for gas exchange
Small sa:v
Have a higher demand for O2
If question asks for structure include…
Rib movement
Trachea
Bronchi and bronchioles
Alveoli
