cardiovascular system

content on the cardiovascular system

composition of the blood

• platelets

• erythrocytes

• leucocytes

• plasma

function of platelets

help to clot blood and repair slightly damaged blood vessels

function of erythrocytes

• red blood cells

• transport oxygen and carbon dioxide

function of leucocytes

• white blood cells

• help fight infection

4 chambers of the heart

• right atrium

• left atrium

• right ventricle

• left ventricle

4 valves of the heart

• tricuspid

• bicuspid

• pulmonary

• aortic

4 major blood vessels of the heart

• vena cava

• pulmonary artery

• pulmonary vein

• aorta

circulation through the heart

vena cava→right atrium→tricuspid valve→right ventricle→pulmonary valve→pulmonary artery→lungs→pulmonary vein→left atrium→bicuspid valve→left ventricle→aortic valve→aorta→body

sequence of excitation of the heart

1. sinoatrial node create electrical impulse

2. impulse travel across atria and arrive at atrioventricular node

3. atrioventricular delay impulse so atria can drain blood to ventricles

4. impulse pass from AV node to bundle of His

5. impulse conduct through purkinje fibres on ventricle walls

6. ventricle forces blood out through main arteries

systematic circuit

oxygenated blood is pumped from heart to body and deoxygenated blood is brought back to the heart

pulmonary circuit

deoxygenated blood is pumped from heart to the lungs and oxygenated blood is returned to the heart

heart rate

number of times heart beats per min

stroke volume

amount of blood pumped by left ventricle per beat

cardiac output

• heart rate x stroke volume

• amount of blood pumped from left ventricle per min

cardiac drift

• upward drift of hr when exercise intensity is constant

• body temp increase causing sweat

• sweat decreases blood volume/blood viscosity higher

• stroke volume lower and heart rate higher

systolic blood pressure

force exerted on arterial walls at ventricular contraction

• on top

diastolic blood pressure

force exerted on arterial walls during ventricular relaxation

• on bottom

trends in systolic blood pressure

- increases in dynamic exercise e.g. running

- increases due to increase in SV

- increases as cardiovascular workload increases

trends in diastolic blood pressure

- remains constant through repetitive action of the muscles on the blood vessels

- constant due to decrease in total peripheral resistance

bp in dynamic/isotonic

• increases systolic in first few mins then levels off

• diastolic bp relatively unchanged

bp in static exercise

• increases both dramatically

• increases peripheral resistance to limit movement of body

distribution of blood in exercise

- q redirects to working muscles

- reduction in blood flow to internal organs

- vasodilation in skeletal muscles and arterioles to working muscles increases blood flow

- vasoconstriction of arterioles to non-working muscles

pre-capillary sphincters within non-active tissue vasoconstrict

- pre-capillary sphincters within working muscles vasodilate

- vasodilation to skin to cool

cardiac adaption due to endurance training

- increased left ventricle volume

- increase SV

- lowers heart rate

- lowers resting heart rate

- increases capilliarisation

- increased a-VO2 (arteries and veins, amount of oxygen used by muscles) difference

max oxygen consumption

- VO2 max

- max amount of oxygen the body can take in, transport and use per min

- depends of lungs to inhale (lung size)

- ability of blood to get oxygen (haemoglobin, capillary density)

- heart to pump blood

- muscles to extract oxygen

- muscles to convert oxygen to fuels