cardiovascular system

1) transport oxygen, carbon dioxide and chemicals. 2) clotting of open wounds. 3) regulation of body temperature.

blood vessels, heart, blood

carry blood away from the heart under high pressure. 1) have a smooth endothelium: that allows blood to flow easily. 2) have elastic tissues: that allows vessel to stretch under the high pressure.

connect arteries to capillaries. 1) share the same features as arteries. 2) help regulate blood pressure.

carry blood from arterioles to organs and body areas. 1) walls 1 cell thick to facilitate substance exchange.

connect capillaries to veins. 1) share the same features as veins. 2) under low blood pressure.

carry blood to the heart under low pressure. 1) less elastic fibre and smooth muscle as pressure is lower. 2) contain valves to prevent backflow of blood.

1) blood comes out of the left ventricle from the heart through the aorta at the highest pressure. 2) as the blood travels through arteries the pressure drops. 3) there is a rise and fall in pressure corresponding to the contraction and relaxation of the ventricles. 4) the artery walls stretch and recoil to smooth the pulsing. 5) as blood moves into arterioles the pressure drops as they are narrower so more friction with vessel walls. 6) capillaries have even lower pressure due to narrow cross-sectional area. 7) in the veins, venules and vena cava the pressure is low. 8) the blood pressure here is increased by the massaging effect of muscles. 9) valves ensure one-way blood flow.

1) blood enters the heart from the body through the vena cava. 2) the deoxygenated blood enters the right atrium. 3) the right atrium contracts forcing the blood through the tricuspid valve into the right ventricle. 4) the right ventricle fills - then pressure from behind the valve closes it. 5) the right ventricle then contracts forcing blood through the semi-lunar valves. 6) the blood leaves through the pulmonary artery to the lungs. 7) the blood re-enters the heart from the lungs through the pulmonary vein. 8) the oxygenated blood enters the left atrium. 9) the left atrium contracts forcing the blood through the bicuspid valve into the left ventricle. 10) the left ventricle fills - then pressure from behind the valve closes it. 11) the left ventricle then contracts forcing blood through the semi-lunar valves. 12) the blood leaves through the aorta to the body.

ensure blood flow is uni-directional. they stop the backflow of blood.

the heart contracts and relaxes without internal stimulation - the signals that cause it come from within the heart.

SAN: in the top of the right atrium. AVN: the lower part of the right atrium.

1) the SAN initiates a wave of depolarisation that causes the atria to contract —–> this is the atrial systole and shows as the P wave on an ECG. - there is a region of non-conducting tissues between the atria and ventricles. This stops the wave of depolarisation from spreading to the ventricles. 2) the wave of depolarisation is carried to the AVN. 3) there is then a slight delay to ensure the ventricles contract after the atria. 4) the AVN is then stimulated and passes the stimulation along the Bundle of His. - the bundle of his is a collection of conducting tissues in the septum. 5) the bundle of his divided into two conducting fibres - the Purkinje fibres - they carry the stimulation around the ventricles. 6) this initiates the depolarisation of the ventricles causing the ventricles to contract ——-> this is the ventricular systole and shows as the QRS complex on an ECG.

during systolic and diastolic the heart valves open and close based on pressure changes. 1) during diastolic —-> bicuspid/tricuspid open and semi-lunar closed. 2) during systolic —-> bicuspid/tricuspid closed and semi-lunar open.

1) chemoreceptors and baroreceptors in the aorta arch measure blood pH and pressure. 2) excess carbon dioxide leads to blood being more acidic. 3) they send messages to the cardiac control centre in the medulla oblongata. 4) this sends messages down one of two pathways to the heart. —–> sympathetic pathway: message to SAN to speed up impulses. ——> parasympathetic pathway: message to SAN to slow down impulses.

c = sensitive to acidity in the heart. b = sensitive to pressure in the heart.

erythrocyte, leucocyte, thrombocyte, plasma.

for carrying oxygen by binding it to haemoglobin.

our immune system and destroying pathogens.

blood clotting.

this is mostly water and dissolved chemicals and carries the carbon dioxide around the body.

it is an inherited characteristic.

ABO blood grouping and Rhesus blood grouping.

your blood group depends on the protein antigen molecules on the erythrocytes and the antibodies found in the plasma.