What is this sound?http://www.youtube.com/watch?v=7eFn8Cgcx8g

Blood and the HeartLearning Objective: • To label and describe the roles of the

main parts of the heart (C)• To explain the route of blood through

the transport system. (B)• To describe double circulation (A)

The Circulatory System The circulatory system is made up of:• Blood• Arteries• Veins• Capillaries• The Heart

Why Does Our Heart beat?

• To pump blood around the body.

Why do we need to pump blood around the body?

•To get oxygen to all the organs and tissues in our bodies.

What happens when we run out of oxygen?

•We need to get more

How do we get more?

• The blood is pumped back to our lungs.•Where it is oxygenated again.

Where does it go from here?

•Back to the heart.

Where does it go from here?

• To the rest of the body.

body’scellsbody’scells

lungslungs

Double circulatory system

This is often shown in a

diagram like this

What happens at each section?

See animation in Go Science 2

p14/15

Double Circulation• So we have two things going on in the heart,

this is known as double circulation. • The blood is being pumped to the body to give

it oxygen AND the blood is being pumped to the lungs to get more oxygen.

• So we say that the heart is spilt into two sections, the left and the right.

4 Chambers• Each side has two

chambers:1. Atria at the top, 2. Ventricles are the

bottom.

What are their functions?

• Atria – Let blood pour into heart and down into ventricles. • Ventricles - Blood from

ventricles pumped out of heat when muscle contracts.

How do we stop the blood from flowing backward?

• Valves stop the flow of blood once it has entered the ventricles. • And also once the blood has been pumped

out the valves stop it from coming back into the heart.

TASK•TASK : Label the diagram of the heart with all the key words.

In the Boxes:

• From Body• To Lungs• To Body• From Lungs

Other:

• Right Atrium• Right Ventricle• Left Atrium• Left Ventricle• Valves

A real heart

The Heart• The heart is made of very special

muscle, CARDIAC muscle. It must keep beating all the time for the rest of a persons life! If you tried to do the same action repeatedly (like the heart) your muscles would get tired and, after a while, they would stop working.

• For example if you clench and unclench your hand continuously, it will get tired, and may even start to cramp.

Structures of the heart

What are the stages in the cardiac cycle?

The blood system

This is the system which carries the dissolved food and oxygen around the body. This includes the heart and the lungs.

Blood cells provide oxygen and the plasma in the blood carries dissolved food to ALL the cells in the

body.

Role of Blood•Transport gases around the body (oxygen and carbon dioxide)•Transport nutrients (i.e. Glucose) around the body

Red Blood Cells

White Blood Cells Platelets Plasma

Description

Diagram

Function

Red Blood Cell• Red blood cells have a perfect biconcave shape

for absorbing and releasing oxygen. • Red blood cells are red only because they

contain a protein chemical called haemoglobin which is bright red in colour.

• Haemoglobin contains the element Iron, making it an excellent vehicle for transporting oxygen.

• They also have no nucleus so they can transport as much oxygen as possible.

There are approximately five million red blood cells per cubic millimetre of blood, slightly more in men and less in women.

The number of red blood cells is higher in people who live at high altitudes.

Red blood cells do not have nuclei.

Haemoglobin• Haemoglobin is an amazing chemical

because if you warm it slightly and add a bit of acid, it will give up all its oxygen.

• As blood passes through the lungs, oxygen molecules attach to the haemoglobin.

• As the blood passes through the body's tissue, the haemoglobin releases the oxygen to the cells.

White Blood Cells• There are usually a few thousand white blood

cells per cubic millimetre of blood. • Their jobs are to produce antibodies and to

engulf bacteria, i.e. they fight disease.

Plasma• Plasma is the liquid part of blood. It

contains many important substances which must be carried around the body.

Products of Digestion (Glucose) Carbon Dioxide Hormones Vitamins

• The plasma is a slightly yellowish in colour.

Platelets• To stop the loss of blood from

wounds• Platelets form a clot which dries up

into a scab. • This is quite a good thing because it

prevents any more blood from getting out and it prevents germs from getting in

Components of Blood• red blood cells -transport of oxygen • white blood cells -defence • plasma -transport of food/waste• platelets -blood clotting