OCR A-level Biology- transport in animals

what are the components of the mammalian circulatory system

Hear, arteries, veins, arterioles, venules, capillaries, blood

what is an open circulatory system

blood is free to travel through the bodily cavities

what is a closed circulatory system

blood is contained within blood vessels

what is a single circulatory system

blood travels through the heart once for every circulation of the body

what is a double circulatory system

blood passes through the heart twice for every circulation of the body

what would be found in a single circulatory system

1 atrium and 1 ventricle

what would be found in a double circulatory system

2 atria and 2 ventricles

what is an advantage of a double closed circulatory system

blood can be transported at multiple pressures increasing the control and efficiency of blood flow

what are the features of an artery

narrow lumen/wide cell wall/high blood pressure/tunica media has a high proportion of smooth muscle and elastic fibres/no valves/walls stretch and recoil to smooth blood flow

what are the features of an arteriole

narrow lumen/wide cell wall/lower blood pressure than an artery/tunica media contains high proportion of smooth muscle/no valves/walls contract and relax to direct blood flow

what are the features of a capillary

narrow lumen/one cell thick/low blood pressure/no valves/contains small holes between cells in the endothelium/walls don’t change size/no tunica media

what are the features of veins

wide lumen/narrow wall/very low blood pressure/tunica media contains elastic fibres/contains valves/walls don’t change size

what are fenestrations

gaps in the capillary wall allowing some substances to pass through

what is the hydrostatic and oncotic pressure at the arteriole end

the hydrostatic pressure is high and the oncotic pressure is low

what happens at the arteriole end of the capillary

water moves out of the capillaries

what is the hydrostatic and oncotic pressure at the venule end of the capillary

the hydrostatic pressure is low and the oncotic pressure is high

what happens at the venule end of the capillary

water moves back into the capillary

what happens to tissue fluid

fluid moves out of the capillary at the arteriole end and moves into the intracellular spaces, bathing cells and then some fluid containing waste products returns to the capillaries at the venule end

what maintain oncotic pressure in the capillaries

proteins in the blood plasma

what does it mean when tissue fluid bathes cells

the tissue fluid provides the cells with useful substances e.g. glucose/fatty acids/oxygen

what happens to water from the tissue fluid that doesn’t return to the capillaries

it drains into the lymph vessels and the plasma returns to the blood in a vein in the neck

what is the equation for when oxygen binds to haemoglobin

Hb + 4O2 → Hb(O2)4

what happens to haemoglobin when oxygen is loaded

it undergoes conformational shape changes making it easier to load more oxygen

when does oxygen have a high affinity for oxygen

when the oxygen concentration is high

when does oxygen have a low affinity for oxygen

when the oxygen concentration is low

what is meant by partial pressure

the pressure exerted by a certain gas in a mixture of gases

how is oxygen transported around the body

haemoglobin is loaded with oxygen in the pulmonary capillaries where the partial pressure of oxygen is high, forming oxyhaemoglobin, oxygen is then unloaded at respiring tissues as the partial pressure of oxygen decreases, oxygen then diffuses into respiring cells

what forms when haemoglobin binds to oxygen

oxyhaemoglobin

how is foetal haemoglobin different to adult haemoglobin

it contains a gamma chain which results in foetal haemoglobin having a higher affinity for oxygen allowing it to unload oxygen from maternal haemoglobin

what is the Bohr shift

the Bohr shift explains how the oxygen dissociation curve shifts to the right in areas of high partial pressure of carbon dioxide which reduces haemoglobins affinity for oxygen

what is the chloride shift

when hydrogen carbonate ions move out of the erythrocyte chloride ions move in to buffer the pH changes in the plasmsa

what does CO2 and H20 form in erythrocytes and what is the catalyst

carbonic acid is formed through the catalyst carbonic anhydrase

what ions does carbonic acid dissociate into

H+ and HCO3-

what does the hydrogen ion from carbonic acid form and what does it do

HHb/haemoglubinic acid which also helps buffer any potential pH changes

what is formed when CO2 binds to the amine terminal

carbaminohaemoglobin

what is most of the CO2 in the body transported as

hydrogen carbonate ions

what 3 compounds can carbon dioxide be transported as

carbon dioxide dissolved in the water of blood plasma/carbaminohaemoglobin/hydrogen carbonate ions

what is the function of the periocardial membrane surrounding the heart

the membrane is inelastic and so prevents the hyperextension of the heart

what occurs during diastole

blood returns to the heart from the superior/inferioir vena cava and flows into the right atrium and the blood flows into the left atrium from the pulmonary vein.

what happens during systole

blood is forced to flow into the two ventricles from the atria as the atrial muscles contract due to the depolarisation of the atria

what are diastole and systole simply

diastole is a period of relaxation and systole is a period of contraction

when do the atrioventricular valves open

when the pressure in the atria is greater than the pressure in the ventricles

when does the atrioventricular valve close

when the pressure in the ventricles is greater than the pressure in the atria

when do the semilunar valves open

when the pressure in the ventricles is greater than that of the aorta

when do the semilunar valves shut

when the pressure in the aorta is greater than the pressure in the ventricles

what is the lub

the atrioventricular valve closing

what is the dub

the semi-lunar valve closing

why is the pressure in the left atrium lower than the pressure in the left ventricle

the atrium only has to move blood into the ventricle whereas the ventricle has to move the blood around the body and so it contracts more strongly than the atrium

what does the p wave represent

the depolarisation and systole of the atria

what does the QRS complex represent

ventricular systole

what does the T wave represent

ventricular diastole/the repolarisation of the ventricles

what happens during bradycardia

the TP interval increases and the hearts beats a fewer number of times per minute

what happens during tachycardia

the TP interval decreases and the heart beats more timer per minute

what does it mean that the heart tissue is myogenic

it can contract on it’s own without nervous impulses to stimulate contration

what area controls the contraction of the heart

the SAN/sinoatrial node

what is the sequence of events occuring in one heartbeat

the SAN contracts causing the depolarisation of the atria and atrial systyole, the wave of excitation reaches the septum which has a layer of non-conducting tissuet, at the AVN (atrioventricular node) the wave of depolarisation transfers to the ventricles, after a few seconds allowing atrial systole to complete, the wave of excitation moves through the purkyne fibres in the septum and up the walls of each ventricle causing ventricilar systole. The ventricles then relax/ventricular diastole, and the SAN contracts again

what happens during ventricular fibrillation

the heartbeat is irregular and the rhythm is lost