1. The Circulatory System
Purpose of the circulatory system:
To circulate necessary materials to all cells (e.g. oxygen, hormones, nutrients)
To remove waste products of cell metabolism
To regulate temperatures in various parts of the body

2. Composition of Blood

3. Plasma: the liquid portion
water: to dissolve minerals and ions and to allow contents of blood to flow
plasma proteins: antibodies for defense against bacteria and viruses
solutes: ions and minerals needed elsewhere in the body and also to maintain isotonic nature of blood

4. Red Blood Cells (Erythrocytes)

5. White Blood Cells (Leucocytes)

6. Platelets

7. Blood Vessels Arteries and arterioles: carry blood away from the heart
walls contain a thick muscle layer that help control the flow of blood and enables them to withstand high pressures

8. Veins and venules: carry blood towards the heart
walls have thinner muscle layer and can stretch more easily; cannot carry blood at high pressures
contain sets of one-way valves to prevent the backflow of blood

9. The Structure of an Artery vs. a Vein

10. The Function of Venous Valves

11. Capillaries: capillary beds connect arteriolesa and venules
capillaries have thin permeable walls (one cell thick)
gas exchange (diffusion of oxygen into cells and carbon dioxide out of cells) occurs at capillaries

13. (gas exchange at the capillaries)
Internal Respiration
(gas exchange at the capillaries)

14. Circulation Pulmonary circulation: supply of blood to the lungs
Cardiac circulation: supply of blood to the heart muscle
Systemic circulation: supply of blood to all other tissues of the body

15. F-1. superior vena cava
F-1
E. aorta E
G. pulmonary artery G
H. pulmonary vein
M. sino-atrial [SA] node H M
C. left atrium
I. pulmonary semi-lunar valve C I
K. mitral valve K
N. AV node N
A. right atrium
L. aortic semi-lunar valve L A
D. left ventricle D
P. Purkinje fibres P
J. tricuspid valve J
O. Bundle of His O
B. right ventricle B
F-2 inferior vena cava
F-2

16. The Heart
· is a muscle that supplies the pressure to move the blood through the arteries
·   is made of cardiac muscle tissue
·  is covered with a sac of epithelial and fibrous tissue called the pericardium that contains liquid which reduces friction as the heart beats

17. 1. the heart consists of two pumps, separated by a muscular wall called the septum that prevents the mixing of blood from the two sides
2. the two pumps in the heart each have two chambers: the atrium (on top), and the ventricle (on the bottom)
3. an atrioventricular valve [bicuspid or tricuspid] controls the flow of blood between the atrium and the ventricle
4. the pulmonary semi-lunar valve and the aortic semi-lunar valve prevent backflow from the arteries leaving the heart

18. 5. The veins [vena cava or pulmonary] bring blood to the heart
6. The arteries [aorta or pulmonary] take blood away from the heart

19. B. Heart Beats
1. the pacemaker (sinoatrial node) is a group of nerve fibers in the right atrium that maintain the beating of the heart
2. the SA node sends a signal that causes the atria to contract from the top and force blood through the atrioventricular valves
3. The signal also reaches the AV node which reacts by sending a signal down the Bundle of His to the bottom of the ventricles.
4. The Purkinje Fibres in the ventricle transmit this signal to start the ventricles contracting from the bottom and this forces blood out the aorta or pulmonary arteries

20. 5. one heart beat = one cardiac cycle
6. each cardiac cycle consists of a systole (a contraction of the heart muscle) and a diastole (a relaxation of the heart muscle)
7. the sounds you hear when your heart beats are the sounds of the valves in your heart closing (first the atrioventricular valves (bicuspid and tricuspid), then the semi-lunar valves)

21. right side
low O2 blood enters the right atrium from the superior or inferior vena cava
the full atrium triggers the SA node which causes both the atria to contract
blood is forced through the bicuspid valve into the ventricle
the ventricle fills and the electrical signal triggers the AV node to send a signal down the Bundle of His
The Purkinje Fibres distribute the signal and the ventricle contracts
Blood is forced past the pulmonary semi-lunar valve and into the pulmonary artery

22. left side
high O2 blood enters the left atrium from the pulmonary vein
the full atrium triggers the SA node which causes both the atria to contract
blood is forced through the tricuspid valve into the ventricle
the ventricle fills and the electrical signal triggers the AV node to send a signal down the Bundle of His
The Purkinje Fibres distribute the signal and the ventricle contracts
Blood is forced past the aortic semi-lunar valve and into the aorta

23. The Spleen
The Spleen is an organ of the Circulatory System which purifies the blood of microbes and old worn out or damaged red blood cells (RBC) or erythrocytes.
It is also an organ of the Immune system as it produces White Blood Cells (WBC) or Leukocytes to help fight infections such as pneumonia and meningitis and synthesize antibodies.

24. Problems in Circulation:
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