1. 6.2 The Blood System

2. The Heart
Transport system consists of the heart and associated blood vessels
Heart pumps blood to pulmonary circuit (lungs) for gas exchange
The heart consists of 4 chambers
2 atria which are on the top (right and left)
2 ventricles which are on the b (right and left)

3. Flow of Blood Heart Blood enters right atrium from vena cava
Goes through the Tricuspid valve
Move to the right ventricle
Pumped through the pulmonary valve (pulmonary artery)
To the lungs (gas exchange)(pulmonary veins)
To the left atrium
Through the Bicuspid valve
To the left ventricle
Through the aortic valve and out of the heart

5. Two Circulatory Paths
Systemic: blood flows from the heart to the body (out the aorta and back through the vena cava)
Pulmonary: blood flows from the heart to the lungs (out through the pulmonary artery to the lungs and back to the heart through the pulmonary vein)

6. Coronary Arteries
Located outside of the heart and supply the heart cells with nutrients and clear metabolic waste products
Can become blocked which can lead to a heart attack

7. Actions of the Heart
Atria receive blood from body (right) and from the lungs (left)
Ventricles are more powerful: pump blood a greater distance
When AV valves are closed (atrioventricular) then the semilunar valves are open and vica versa
Valves control the direction of blood flow

8. Control of the Heart Myogenic muscle contraction
- Signal for heartbeat comes from the heart not the brain
- Signal originates in the Sinoatrial Node (SA) signal is then sent to the AV node
- SA is a specialized set of cardiac cells that generate an electric impulse
- The impluse spreads across the atria at a speed of approx 1m per sec., causing the atria to contract

9. SA node and Bundle of His

10. Influences to heart rate
Heart beat set by SA node
Nervous system can influence heart rate by impulses delivered by medulla oblongata
Increase or decrease if there is a need for oxygen
Endocrine system also influences heart rate
Increase or decrease by releasing adrenalin

11. Arteries Largest circulatory vessels Take blood away from the heart
Have high pressure
Aorta is the largest artery in the body
Most carry oxygenated blood except the pulmonary artery

12. Veins Bring blood back to the heart
Carry most deoxygenated blood (except the pulmonary vein)
Superior and inferior vena cava (top and bottom) bring blood back to the heart

13. Capillaries Most numerous of all blood vessels
Contain only endothelium
One cell thick
Carry out exchange of materials between blood and body cells

14. Blood flow through arteries, veins and capillaries Heart  arteries  arterioles  capillaries  venules  veins  heart

15. Vessel Tissue Size Function
Artery
Endothelium,
Smooth muscle, connective tissue (with elastic fibers)
Largest (thick layer of smooth muscle and connective tissue)
Takes blood away from the heart and helps maintain blood pressure (pumps blood)
Vein
Second largest (thin layer of smooth muscle & connective tissue)
Brings blood back to heart and helps maintain blood pressure (pumps blood)
Capillary
Endothelium only
Thinnest and most numerous
Allows exchange of material with body cells

16. Composition of Blood Cell fragments called…
A straw-coloured liquid called…
Plasma
Red Blood Cells
White Blood Cells
Carries dissolved substances:
CO2
Other wastes
Hormones
Food molecules
Carry oxygen
Fight Infection
Help with blood clotting