transport in animals

Question 1

how does tachycardia affect the body

Answer 1

less blood leaves the heart as the ventricles have less time to fill

Question 2

why does foetus have higher affinity for o2

Answer 2

so that it can bind to o2 in lower partial pressures in the placenta

Question 3

why does tissue fluid not contain erythrocytes

Answer 3

as they are too large to move through endothelium cells

Question 4

what does haemoglobin do

Answer 4

Hb has a high affinity for oxygen it binds to oxygen in the lungs forming oxyhaemoglobin which is then released in respiring tissues

Question 5

how are hydrogen carbonate ions formed

Answer 5

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+

Question 6

bohr effect

Answer 6

when theres a high concentration of co2
reduces affinity of Hb to oxygen so more oxygen is released where needed.

Question 7

why is the fetal hb curve to the left

Answer 7

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.

Question 8

how do substances enter tissue fluid from capillaries

Answer 8

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

Question 9

what causes fluctuations in pressure across the aorta

Answer 9

systole increases pressure diastole decreases pressure

Question 10

advantages of blood inside vessels

Answer 10

increases rate of flow and can maintain higher blood pressure

Question 11

how does artery withdstand and maintain high blood pressure

Answer 11

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

Question 12

how does pressure changes in heart cause atrioventricular valves to close

Answer 12

ventricular(systole) contraction raises ventricular pressure so its higher than atrial pressure so blood moves which closes the valve

Question 13

what do SAN and AVN do

Answer 13

SAN initiates heartbeat and sends waves of excitation over atria walls AVN delays impulse and sends it to purkyne tissue/

Question 14

what tissue is found in walls of heart chambers

Answer 14

cardiac tissue

Question 15

whys there a delay of excitation of atria and ventricles

Answer 15

to allow atria to fully contract and empty

Question 16

whys a wave of excitation carried to the apex

Answer 16

so that ventricular contraction starts at the bottom to push blood upwards

Question 17

why dont eryhtrocytes use oxygen

Answer 17

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

Question 18

what happens to excess tissue fluid

Answer 18

it cant be reabsorbed

Question 19

how is the heart involved in moving tissue fluid

Answer 19

heart contracts so ventricle produces high blood pressure which forces water out of capillaries

Question 20

movement of tissue fluid

Answer 20

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

Question 21

why do arteries have smaller lumes

Answer 21

smaller lumens allow artery to maintain high pressure,veins have larger lume as it reduces friction so blood can travel at a slower rate.