2.1 blood circulation

Blood circulatory system

The function of blood circulatory systems are to:i. Supply oxygen to all body.ii. Eliminate carbon dioxideiii. Transport waste product like carbon dioxide and urea for elimination.

Artery Vein

a) Humans have a close blood circulatory system.

b) Blood is carried to the heart by vein blood vessel and pump out from the heart through artery blood vessel.

Artery

Vein

Artery – the blood vessel that carries blood out of the heart

Vein – the blood vessel that carries blood into the heart

Blood capillaries

Blood capillaries-Act as connectors that joint the blood vessel of arteries to veins

CO2 blood

O2 blood

Go to body

The heart is a muscular organ which contract and relaxes without stopping to pump and circulate blood to the whole body.

The heart has four large chambers:i. Left atriumii. Right atriumiii. Left ventricleiv.Right ventricle

Left atrium and right atriumare situated at the upperpart of the heart

Left ventricle and right ventricle are situated at the lower part of the heart.

The space in the atrium is smaller than in the ventricle.

The wall of ventricle is thicker and stronger than atrium

The wall of left ventricle is thicker and more muscular compared to right ventricle.

This is because strongerpressure is needed by the left ventricle to pump the blood to our body.

The valve in the heart enable blood to flow in one direction only. Blood is prevented from flowing back.

There are 3 types of valve inthe heart:i. Tricuspid valveii. Bicuspid valveiii. Semi lunar valve

The left chamber of the heartcontains oxygenated bloodThe right chamber containsdeoxygenated blood.

TYPE OF VALVE POSITION FUNCTIONTricuspid Between the right

atrium and right ventricle

Prevents blood in the right ventricle from flowing back to the right atrium

Bicuspid Between the left atrium and the left ventricle

Prevents blood in the left ventricle from flowing back to the left atrium

Semilunar At the base of the pulmonary artery and the aorta

Prevents blood leaving the heart from flowing back

TYPE OF BLOOD VESSEL

FUNCTION

Pulmonary artery Carries deoxygenated blood from the heart to the lungs

Pulmonary vein Carries oxygenated blood from the lungs to the heart.

Aorta Carries oxygenated blood from the heart to the whole body.

Vena cava Channels deoxygenated blood from all parts of the body to the right atrium.

Four blood vessels are connected to the heart:

Right ventricle

S

Vena cava

TricuspidValve

Right atrium

Left ventricle

Bicuspid valveLeft atrium

Semilunar valve

Pulmonaryveins

Vena cava

Aorta Pulmonaryartery

1. The vena cava caries deoxygenated blood from all the body to the right atrium.

2. When it is filled with blood, the wall of the right atrium will contract and push the blood through the tricuspid valve into the right ventricle.

3. When the right ventricle is filled with blood, its wall will contract and push the blood through the semilunar valve into the pulmonary artery and go to the lungs.

4. Gaseous exchange takes place in the lungs. Carbon dioxide diffused out and oxygen diffused into the blood.

5. Oxygenated blood then flows from the lungs into the left auricle through the pulmonary vein. 6. The left auricle wall contracts and pushes blood through the bicuspid valve into the left ventricle.

7. The contraction of the left ventricle wall pushes blood through the semilunar valve into the aorta.

8. The aorta then carries the blood to the whole body.

The pathway of blood circulation:

Vena cava

Right auricle

Tricuspid valve

Right ventricle

Semilunar valve

Pulmonary artery

Semilunar valve

Left ventricle

Bicuspid valve

Left auricle

Pulmonary vein

Lungs

Aorta

Whole body

Video : Heart 1

Video: Heart 2

Blood vessels in humans

Blood vessels are tubes in the body that channel blood

3 types ofblood vessels

Artery

Vein

Blood capillary

Artery Vein Blood capillaryStructureFunction Carries

blood out of heart

Carries blood into the heart

Carries blood from artery to vein

Type of blood carried

Oxygenated blood (except pulmonary artery)

Deoxygenated blood (except pulmonary vein)

Oxygenated blood (artery)Deoxygenated blood (vein)

Rate of blood flow

High pressure blood flow faster

Low pressure blood flow slowly

Blood flows very slowly to enable diffusion process

Artery Vein Blood capillary

Thickness of blood vessel wall

Has thick, muscular and elastic.

Has thin less muscular and less elastic.

Has porous and thin wall to enable gas exchange

Lumen size

Small Big Very small

Existence of valve

No Yes No

Oxygenated blood Deoxygenated bloodDifference

PresentNot present

High

Not presentArtery and pulmonary

vein

OxygenCarbon dioxide

Concentration of digestion

food (glucose)

Waste product(urea)

Blood vessel that carries it

Not presentPresentVery low

PresentVein and

pulmonary artery

Deoxygenatedblood

Vein Artery

Blood capillary

Oxygenatedblood

Relationship between artery, vein and blood capillary

Cell

Vena cava andveins

Arteries andaorta

1. Heart disease is caused by:a. Damage to the valve in the heartb. Failure of the ventricle and atrium muscular wall to contract

c. Blockage of blood supply to the heart as a result of cholesterol deposits.

The importance of maintaining a healthy heart is toa. Avoid contracting heart disease. If serious can cause deathb. Ensure that our body cells get enough supply of oxygen