Lungs Flashcards
where do arteries carry blood?
heart to capillaries
features of arteries?
pressure reservoir - thick walls and smooth muscle to withstand pressure
controls flow to capillary beds
connective tissue limits stretch to avoid rupture
dampen oscillations in pressure and flow - even flow
how is flow to capillary beds controlled?
smooth muscle in arteriole contracts decreasing flow or relaxes allowing flow
rings of smooth muscle controls flow between arterioles and venules
controlled by sympathetic nervous system blood either goes to organs or is diverted e.g to muscle during exercise
pulse pressure
systolic - diastolic
what happens in arterioles?
decline in pressure due to friction
whats special about veins?
no pulse
features of veins?
can't retain shape without blood transports from capillaries to heart storage reservoir valves prevent backflow skeletal muscle activity helps return blood to heart
diseases involving circulatory system?
thrombophlebtis - pooling of blood leading to clots
deep vein thrombosis - blood clots (embolus) if in brain its a stroke
heart disease - block of blood vessel by clot
atherosclerosis - cholesterol plaques and fiborous tissue in walls of arteries causing them to loose their elasticity - if breaks thrombus forms
where do capillaries take blood?
arterioles to venules
features of capillaries?
dense cross section increases velocity decreased pressure decreased friction increased
breathing process?
air come in though nasal cavity where its warmed/moistened
joins food passage at pharynx air comes in dorsally, leaves ventrally - food opposite
leaves pharynx and enters larynx where it passes into the trachea which divides into the bronchi which subdivides into the alveoli
what prevents food going into the trachea?
epiglotis/soft pallate
what does the rate of transfer depend on?
area, distance so need large area and small diffusion distances
features of trachea?
mucus secreted, cartilage
features of the alveoli?
fluid film, smooth muscle, elastin fibres, large surface area
how do frogs breathe?
postive pressure
gulp air into mouth, close nares and raise buccal floor forcing air into lungs, squeeze on lungs and elasticity forces air out, close glottis and raise buccal floor to empty mouth
how does inhalation work?
diaphragm contracts, space between pleural membranes filled and air brought in
how does exhalation work?
diaphgram relaxes, elasticity drives air out and cycle replaces air in lungs with air outside
how is carbon dioxide transported?
5% as dissolved CO2
5% attatched to haemoglobin
90% as bicarbonate ions
features of haemoglobin?
protein with 4 subunits and a haem group with iron attatched so easier to bind with oxygen
what is cooperativity?
when one subunit looses an oxygen it makes it easier for the rest to loose it - decreasing affinity
