gas exchange in humans Flashcards
what are the properties of exchange surfaces in humans?
thin
permeable
moist
large SA
mechanism to maintain diffusion gradient
what are the components of the respiratory system?
nasal cavity
trachea (with rings of cartilage)
bronchus
bronchiole
alveoli
lungs
plueral cavity (filled with fluid)
intercostal muscle
diaphragm
what is the trachea made of?
cartilage
smooth muscle
ciliated epithelium
lumen
goblet cells
blood vessel
what does a goblet cell do?
secrete mucus to trap dirt/dust/microbes
what does ciliated epithelium do?
waft mucus up trachea/bronchi to be swallowed
what does smooth muscle do?
adjusts size of airways
contracts causing constriction of airways
restricts air flow
what does cartilage do?
supports trachea and bronchi
prevents collapse during inspiration
what do elastic fibres do?
elastic recoil of alveoli in expiration
alveoli facts?
well ventilated to ensure air inhaled and exhaled
good blood supply from capillaries
maintains concentration gradient (blood always moving)
alveolar cavity filled with air
what does ventilation of the lungs do?
allows lungs to replace used air with fresh air to keep concentration gradient
what happens during inspiration of the lungs?
external intercostal muscles contract
ribcage is pulled upwards and outwards
diaphragm contracts
volume increases
pressure decreases
air is forced into lungs
what happens during expiration?
external intercostal muscles relax
ribcage falls downwards and inwards
diaphragm relaxes
elastic recoil of lung tissue
volume decreases
air pressure increases
air is forced out of the longs
what happens during expiration (forced)?
intercostal muscles contract
pulls ribcage downwards and in
abdominal muscles contract pushing diaphragm upwards
volume decreases
pressure increase
air is forced out
