surfaces Flashcards
what factors affect the need for an exchange system?
size
SA to V ratio
level of activity
what adaptations give a large SA to V ratio
shape of body e.g flatworm
how should SA to V be represented
ratio: 1
e. g 2.5:1
what are the features of a good exchange surface?
A large surface area through folding
a thin barrier
a good blood supply
what is the diaphragm
a layer of muscle beneath the lungs
what are the intercostal muscles
muscles between the ribs
contraction raises ribcage.
what gives lungs a large surface area?
the number of alveoli makes the total SA more than that of our skin 70m^2
it is lined by moisture preventing from collapse.
permeability of lungs
barrier is comprised of alveoli wall and capillary wall which allow diffusion as o2 and CO2 molecules are small and non polar
thin barrier of lungs
alveolus 1 cell thick capillary wall 1 cell thick both walls squamous cells both walls in close contact narrow capillary so blood cell closer to air
blood supply to the lungs
CO2 transported to lungs
O2 transported away from lungs
Inspiration
diaphragm contracts moving down intercostal muscles contract raise ribs volume of chest increases pressure is chest drops air moves in
Expiration
diaphragm relaxes and is pushed up intercostal muscles relax and ribs fall (or can contract during coughing) volume of chest decreased pressure in lungs increases air forced out
cartilage
form of connective tissue
elastic fibres
protein fibres that deform and recoil to original size
smooth muscle
involuntary muscle
what helps push air out during expiration?
elastic fibres in the alveoli walls
what are the requirements of the airways?
be large enough for sufficient air flow
be supported to prevent collapse
be flexible for air movement
how are the airways supported
by c shaped rings of cartilage allowing flexibility
the bronchioles
narrower that bronchi
larger ones have some cartilage but smaller ones have none
comprised of smooth muscle and elastic fibres
how can the air flow be controled
by the contraction of the smooth muscle making the lumen narrow
why is controlling air flow important
if there is harmful substances in the air
what elongates the smooth muscle after contraction?
the elastic fibres
oxygen uptake
the volume of oxygen absorbed by the lungs in one minute
tidal volume
the volume of air inhaled or exhaled in one breath usually at rest
spirometer
a device that can measure movement of air into and out of the lungs
vital capacity
the greatest volume of air that can be expelled from the lungs after taking the deepest breath possible
what does a float chamber spirometer consist of
a chamber of air or medical grade oxygen floating on a tank of water
movement of lid is measured
what happens to the exhaled air
it passes through a soda lime which absorbs CO2
precautions with spirometer
healthy subject fresh soda lime no air leaks sterilised mouth piece water chamber not overfilled
what does vital capacity depend on?
the size of the person
the age
level of exercise
what is residual volume
volume of air that remains in lungs after forced expiration
aprox 1.5dm^3
how can we find rate of O2 uptake?
CO2 is absorbed by soda lime so the volume in the tank decreases therefore by finding the gradient of the decrease we can find the rate of decrease
breathing rate
breaths per min
filaments
slender branches of tissue that make up the gill often called primary lamellae
lamellae
folds of the filament to increase SA sometimes called secondary lamellae
operculum
bony flap that covers and protects the gills
spiracle
external opening that allows air in and out of tracheae
tracheal system
a system of air filled tubes in insects
how does O2 concentration in water compare to air
its lower
what provides a large surface area on the gills?
the lamellae folds on the fillaments
point of counter current flow
to absorb the maximum amount of oxygen from water
how is water pushed over the gills
the bucal cavity opens and closes pushing water down and movement of operculum is coordinated with this movement
how do insects transport oxygen?
with an open circulatory system acting as both blood and tissue fluid
airs pathway through the insect
enters through spiracle and enters tracheal system first through trachea the branch of into tracheoles filled with tracheal fluid were gas exchange takes place
ventilation in insects
sections of trachea system expands and contracts
movement of wings alter volume of thorax
