transport in animals Flashcards
how does tachycardia affect the body
less blood leaves the heart as the ventricles have less time to fill
why does foetus have higher affinity for o2
so that it can bind to o2 in lower partial pressures in the placenta
why does tissue fluid not contain erythrocytes
as they are too large to move through endothelium cells
what does haemoglobin do
Hb has a high affinity for oxygen it binds to oxygen in the lungs forming oxyhaemoglobin which is then released in respiring tissues
how are hydrogen carbonate ions formed
carbon dioxide enters erythrocytes and reacts with water . carbonic anyhdrase catalyses the reaction to form carbonic acid . it then dissociates to form hydrgogen carbonate ions and H+
bohr effect
when theres a high concentration of co2
reduces affinity of Hb to oxygen so more oxygen is released where needed.
why is the fetal hb curve to the left
as the placenta has a low partial pressure of oxygen. foetal hb has a higher affinity for oxygen so can take up some oxygen at lower po2.
how do substances enter tissue fluid from capillaries
via diffusion down the concentration gradient. the hydrostatic pressure in the capillaries is higher than in the tissue fluid so it moves down the pressure gradient into the tissue fluid
what causes fluctuations in pressure across the aorta
systole increases pressure diastole decreases pressure
advantages of blood inside vessels
increases rate of flow and can maintain higher blood pressure
how does artery withdstand and maintain high blood pressure
to withdstand the wall is thick as it has collagen which provides strength and the endothelium is folded so artery wall isnt damaged.
to maintain pressure theres a thick layer of elastic tissue which causes it to recoil and it has smooth muscle which constricts the lumen
how does pressure changes in heart cause atrioventricular valves to close
ventricular(systole) contraction raises ventricular pressure so its higher than atrial pressure so blood moves which closes the valve
what do SAN and AVN do
SAN initiates heartbeat and sends waves of excitation over atria walls AVN delays impulse and sends it to purkyne tissue/
what tissue is found in walls of heart chambers
cardiac tissue
whys there a delay of excitation of atria and ventricles
to allow atria to fully contract and empty
whys a wave of excitation carried to the apex
so that ventricular contraction starts at the bottom to push blood upwards
why dont eryhtrocytes use oxygen
dont use oxygen they carry as oxygen is bound to haemoglobin while being transported so cannot be used, and also they lack mitochondria, therefore can’t use the oxygen for aerobic respiration. Also erythrocytes are moved by mass flow so they don’t need ATP produced from respiration to move and need less ATP for metabolic processes due to lack of organelles
what happens to excess tissue fluid
it cant be reabsorbed
how is the heart involved in moving tissue fluid
heart contracts so ventricle produces high blood pressure which forces water out of capillaries
movement of tissue fluid
at the arterial end hydrostatic pressure is higher than than oncotic so fluid moves out of the capillary. At the venous end hydrostatic pressure is lower than oncotic pressure so fluid moves back in.imbalance of large plasma proteins between blood and tissue fluid creates oncotic pressure
why do arteries have smaller lumes
smaller lumens allow artery to maintain high pressure,veins have larger lume as it reduces friction so blood can travel at a slower rate.
