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Mammalian gaseous exchange & ventilation 3.1.1 - Coggle Diagram
Mammalian gaseous exchange & ventilation 3.1.1
mammalian respiratory system
lies within the thoratic cavity (aka the thorax or chest cavity)
all mammals have evolved to have lungs to ensure efficient gas exchange between air & blood
air enters body through nasal cavity where air become warmer & cleaner
trachea divides into left bronchus & right bronchus when entering each lung
inside the lungs the bronchi divide into many smaller bronchioles
bronchioles end in masses of alveoli
important function of nasal cavity
hairy lining - hairs trap dust & bacteria in mucus & prevent them from reaching lungs which could cause infection
moist surfaces - increases the humidity of incoming air, reduces evaporation of water in lungs
large SA & good blood supply - warms air as it passes into the body
function of ribcage
protect lungs
help increase volume of throatic cavity during inhalation through attachment to intercostal muscles
function of pleural membranes
stick outside of lungs to the inside of the throatic cavity so lungs follow chest movements
secrete plural fluid
cartilage
trachea is strengthened by C-shaped rings of cartilage which help to keep the air way open/prevent it collapsing under pressure
C-shaped not full circle cause needs to be flexible so oesophagus can accommodate food, swallow efficiently & do peristalsis
function of plural fluid
lubricate lungs to reduce friction allowing smooth movements of lungs when the inhale & exhale
what is the diaphragm
sheet of muscular tissue that lies below the lungs
breathing & respiration
breathing = the physical process of ventilating the lungs - only happens in animals with lungs
respiration = a chemical reaction that releases energy - occurs in every living cell (mitochondria)
Ventilation
inhalation & exhalation requires a difference in air pressure & relies on the thorax being an air tight cavity
https://docs.google.com/document/d/1Spdg4fRhoe7CWAkiYxPWn5Wy3lRw1bK3_8qi3BFqpEQ/edit
inhalation
4) diaphragm lowers
5) volume of chest increases
3) diaphragm muscles contract
6) pressure in chest decreases
2) ribs move up
7) air pressure in lungs is lower than atmospheric pressure
1) intercostal muscles contract
8) air rushes in to lungs
exhalation
5) volume of chest decreases
6) pressure in chest increases
4) diaphragm raises
7) air pressure in lungs is higher than atmospheric pressure
3) diaphragm muscles relax
8) air rushes out of lungs
1) intercostal muscles relax
2) ribs move down
Inhalation
active process - contraction requires energy
external intercostal muscles contract - raises rib cage up & outwards
diaphragm contracts & flattens - increases volume of thoratic cavity, decreases pressure in thoratic cavity
this forces air into lungs from high to low air pressure
Exhalation
passive process
external intercostal muscles relax - lowers rib cage in & downwards
diaphragm relaxes & returns to dome shape - decreases volume of thoratic cavity, increases pressure in thoratic cavity
forces air out of lungs from high to low ait pressure
Intercostal muscles
during inhalation external intercostal muscles contract
during exhalation external intercostal muscles relax & internal intercostal muscles can contract to help force air out of lungs more forcefully
only usually happens during exercising or coughing & sneezing
bell jar model of ventilation
balloons = alveoli, bell jar = thoratic cavity, rubber sheet = diaphragm
exhalation
push rubber sheet up - decreases volume inside bell jar & increases pressure in the jar, air is forced out of balloons & into atmosphere - balloons deflate
inhalation
pull rubber sheet down - increases volume inside bell jar & decreases pressure, air is forced into jar due to pressure difference with outside atmosphere - balloons inflate
gas exchange & adaptation of alveoli
https://docs.google.com/document/d/1PXHQOZ8MdKG54JeScUAc74NMc_VmP3N1fyF70CXI5po/edit
