Circulation. Body In action SG Biology

Transcription

1 Circulation Body In action SG Biology

2 What you need to know! Substances are transported around the body, for example from where they are taken into the body to cells; or from cells to where they are removed from the body, by the circulation system, the heart, the blood vessels and the blood.

3 Learning Outcomes Lesson 1 To be able to explain the circulation system are a double circulation. To label a diagram of the body showing the major blood vessels, saying in each case if the blood is oxygenated of deoxygenated. To understand the main features of arteries, veins and capillaries

4 Why do we need a circulatory system? Transport over short distances is achieved by diffusion, osmosis or active transport. Situation in larger organisms is different Giant redwoods need to transport water to a height of 100m without the expenditure of energy

5 Why do we need a circulatory system? Cell Metabolism What do cells need? Amino acids, glucose, oxygen Removal of waste products What is important in determining whether an organism has a transport system? Size Surface area to volume ratio Level of activity

6 Features of transport systems Suitable medium to carry materials Closed system of tubular vessels Mechanism to maintain flow in one direction A mean of controlling the flow of the transport medium to suit the changing needs

7 Types of circulation Open circulation E.g. insects Closed circulation Single circulation e.g. fish Double circulation e.g mammals

8 Circulation System Double Circulation The heart is divided into two halves, the left and the right. The blood on the right side does not mix with the blood on the left. So the circulation is in two parts. The blood passes through the heart twice in one circuit, this is called a double circulation. Blood picks up oxygen in the lungs (oxygenated), and gives up its oxygen to the body cells (deoxygenated).

9 Double Circulation

10 Blood Vessels The blood flows from the heart to organs through arteries and returns through veins. Arteries have thick walls containing muscle and elastic fibres, they carry blood to the organs. Arteries contract and bounce back to force the blood along, this bouncing back can be felt as a pulse as the blood flows through. Veins have thinner walls and often have valves to prevent the back-flow of blood.

11 Blood Vessels In the organs the blood flows through capillaries. These are very narrow, thin-walled blood vessels, they are only one cell thick. Substances needed by the cells in body tissues pass out of the blood, and substances produced by cells pass into the blood through the walls of the capillaries.

12 Learning Outcomes Lesson 2 To be able to label a diagram of the heart To take part in a heart dissection, demonstrating the main parts of the heart. To be able to describe the events in the cardiac cycle.

13 The Structure of the heart

14 Structure of heart pulmonary artery vena cava right atrium tricuspid valve right ventricle aorta pulmonary vein left atrium semi-lunar valve bicuspid valve tendon supporting valve left ventricle muscle

15 The Heart The heart pumps blood through the circulatory system all round the body. The heart is a double pump. The right side collects blood from the body and pumps it to the lungs. The left side collects blood from the lungs and pumps it to the rest of the body.

16 Heart Dissection

17 Valves in the heart There are three main types of valves in the heart. These are: Semi-lunar valves aorta and pulmonary artery Tricuspid valves Bicuspid valves The valves are attached to the wall of the heart by tendons (heart strings), which prevent the valves being turned inside out.

18 What do these valves do? Each valve has a particular function Semi-lunar valves these prevent blood sucking back into the ventricles when they stop contracting. Tricuspid valve (between the right atrium and ventricle) and bicuspid valve (between the left atrium and ventricle) these prevent blood passing up into the atria when the ventricles contract.

19 The Cardiac Cycle Draw a flow chart to demonstrate the blood flow through the heart. Mention which muscles are contracted Which valves are open Which valves are closed