1. Blood System The Slide 001

2. Application William Harvey’s discovery of the circulation of the blood with the heart acting as the pump.

3. Arteries Convey blood away from the heart Under high pressure –From the contraction of the ventricles Walls composed of elastin fibres & involuntary muscles –Elastin stretch & then recoil. The recoil helps propel blood down the artery Slide 002

4. Comparison of arteries, veins & capillaries

5. Artery Walls Tunica externaa tough outer layer of connective tissueout Tunica mediaA thick layer containing smooth muscle and elastic fibres made of the protein elastin Tunica intimaA smooth endothelium forming the lining of the artery

6. Arterial blood pressure Blood enters under high pressure Systolic pressure Pushes artery walls outward, widens lumen, stretches elastic fibres

7. Blood pressure End of heartbeat the pressure falls Stretched fibres squeeze blood into the lumen Diastolic pressure

8. Measuring Blood Pressure

9. Vasoconstriction/Vasodilation Vasoconstriction – smaller diameter = high pressure Vasodilation – larger diameter = less pressure

10. Arterioles High density of muscle cells Respond to various hormones & neural signals to control blood flow downstream

11. Capillaries Transport blood to tissue except for the lens and cornea of the eye

12. Bruises Damage to the capillary walls Leakage of plasma & blood cells into interstitial fluid Hemoglobin broken down to green & yellow bile pigments Phagocytes remove remaining blood cells by exocytosis

13. Veins Transport blood toward the heart Blood is at low pressure Greater dilation 80% of a sedentary persons blood is in the veins

14. Veins Blood flow assisted by gravity & by pressure exerted on them by other tissue Veins contain pocket valves to prevent backflow (3 cup shaped flaps Allows blood to flow in only one direction

15. Double Circulation Systemic – to the body Pulmonary – to the lungs Heart is a double pump, delivering blood under different pressures separately to the 2 circulations

16. Heart structure

17. Atherosclerosis

18. The development of fatty tissue call atheroma Low density lipoproteins (LDL) containing fats & cholesterol accumulate Phagocytes engulf the fats & cholesterol by endocytosis & grow large Smooth muscle cells migrate to form a tough cap over the atheroma Artery bulges into the lumen = narrowing

19. Causes???? High blood concentrations of LDL (Low density lipoprotein) Chronic high blood glucose concentrations due to overeating, obesity or diabetes Chronic high blood pressure due to smoking, stress or any other cause Consuption of trans fats, which damage the endothelium of the artery

20. More recent theories Infection of the artery wall with Chlamydia pneumoniae Production of trimethylamine N-oxide by microbes in the intestine

21. Sinoatrial Node The heartbeat is initiated by a group of specialized muscle cells in the right atrium called the sinoatrial node

22. Working of the Sinoatrial Node Cardiac muscle can contract without stimulation from motor neurons (myogenic) Membrane of the cells depolarizes when the cell contract & this activates adjacent cells Contraction

23. Heartbeat Sinoatrial node set the pace for the heart beat = pacemaker Can be replaced with an artificial one

24. Contractions Atrial Sinoatrial node initiates a heartbeat Goes to walls of the atria Less than 1/10 th of a second Ventricular After 0.1 second delay the signal goes to the ventricles allows time for the atria to pump blood to the ventricles

25. Contractions Systole = heart contracting Diastole = heart at rest 120/80 mm Hg –(South Dakota)

26. One Cardiac Cycle ~.8 seconds

27. Cardiac Cycle ~ 0.0 – 0.1 seconds The atria contract – small pressure increase which pumps blood from atria to ventricles (open atrioventricular valves) Semilunar valves are closed (blood pressure in arteries drops to its minimum)

28. Cardiac Cycle ~ 0.1 – 0.15 seconds The ventricles contract which causes the atrioventricular valves to close Semilunar valves remain closed

29. Cardiac Cycle ~ 0.15 – 0.4 seconds Pressure in ventricles rises above pressure in the arteries Semilunar valves open & blood is pumped out Pressure slowly rises in the atria as blood drains into them from the veins & they fill

30. Cardiac Cycle ~ 0.4 – 0.45 seconds The contraction of the ventricular muscles wanes & pressure inside the ventricles rapidly drops below the pressure in the arteries The semilunar valves close Atrioventricular valves remain closed

31. Cardiac Cycle ~ 0.45 – 0.8 seconds Pressure in the ventricles drops below the pressure in the atria Atrioventricular valves open Blood from the veins drains into the atria and from there into the ventricles, causing a slow increase in pressure

32. Changing the heart rate The sinoatrial node responds to signals from outside the heart Includes signals from branches of two nerves originating in the medulla oblongata (cardiovascular centre)

33. Changing the heart rate

34. Cardiovascular centre receives inputs from receptors that –Monitor blood pressure –Blood pH (reflects CO 2 concentration) –Oxygen concentration

35. Speed up the Heart Low blood pressure Low oxygen concentration Low pH

36. Slow down the heart High blood pressure High oxygen concentration High pH Why is Sheldon blowing into a bag? What will it accomplish?

37. Epinephrine Epinephrine in the blood stream Also called adrenaline Adrenal glands located on top of kidneys

38. Epinephrine Secretion is controlled by the brain Amount secreted increases with ”fight or flight”