Transport + Cardiac cycle

Open circulatory system

blood moves directly through tissue

held in cavity called haemocoel

Closed circulatory system

blood moves in blood vessels

-single = blood goes through heart once

-double = blood goes through heart twice

Describe fish's circulation system

single

heart pumps deoxygenated blood into gill then oxygenated blood in carried to tissues

pressure reduced by capillary network

pulmonary circulation

serves lungs as right side of heart pump deoxygenated blood to lungs

systemic circulation

serves body tissue as left side of heart pump oxygenated blood to tissues

Describe order of blood flow

deoxygenated blood enters through superior + inferior vena cava

flows through right atrium + right atrio-ventricular valve (tricuspid) + ventricle

through pulmonary valve then out through pulmonary artery to lungs

oxygenated blood flows through pulmonary vein into left atrium + left atrio-ventricular valve (bicuspid) + ventricle

passes through aortic valve then aorta to the body

Describe structure of Arteries

thick muscular walls to withstand high blood pressure

branch into arterioles then capillaries

Describe structure of veins

large lumen and thin walls

blood pressure + flow rate is lower

have semi-lunar valves to ensure one direction flow

Properties of valves

prevent backflow of blood

close under high blood pressure when behind pressure is greater than in front

Structure of capillaries

from lungs blood collects into venules which take it to heart

thin walls of one layer endothelium

have pores so permeable

small diameter = slow rate

Describe atrial systole

atrium walls contract + increase blood pressure in atria

blood pushes through tricuspid + bicuspid valves into currently relaxed ventricles

Describe ventricular systole

ventricle walls contract + blood pressure increases

blood pushed through semi-lunar valves and out of heart

tricuspid and bicuspid valves closed due to rise in ventricular pressure

when blood pushed out ventricles relax so volume increases pressure decreases

Describe blood pressure is aorta

highest

rises and falls rhythmically with ventricular systole

drops in arterioles and further in capillary beds

What happens to pressure in arteries + capillaries as distance from heart increases?

pressure falls

describe structure of arteries and veins

tunica intimata - innermost layer of endothelium which is smooth so less friction + resistance to blood flow

tunica media - middle layer with elastic fibres for stretching in changes in blood pressure

tunica externa - collagen fibres to resist overstretching