1. Blood Vessels

2. Flow of Blood through Blood Vessels
Heart
Artery
Arterioles
Capillaries
Venule
Vein

3. Arterial System

5. Arterioles the major determinant of blood pressure
The major determinant of blood flow to the individual organs.
Blood flow to individual organs can be regulated by controlling the diameter of the arterioles.
Vasodilation lowers resistance
Vasoconstriction increases resistance and results in decreased flow through that particular arteriole.

6. Arteries vs Arterioles

7. Capillaries

8. Veins Larger and more compliant (stretchable) than arteries
Hold more blood.
Containing 60% of the total blood volume at rest.
As physical activity:
vasoconstriction, driving more blood back to the heart and increasing circulation.
one-way valves that insure unidirectional flow of blood.

10. Skeletal muscle pump.
Veins pass between skeletal muscles. The contraction of skeletal muscle squeezes the vein, thus increasing blood pressure in that section of the vein. Pressure causes the upstream valve (furthest from the heart) to close and the downstream valve (the one closest to the heart) to open. Repeated cycles of contraction and relaxation, as occurs in the leg muscles while walking, effectively pumps blood back to the heart.

11. Review Questions Pg , 16,17

12. Fig. 20.8

13. Varicose Veins

14. Systemic Blood Pressure

15. Arterial BP “Normal” BP = 120/80 Hg/mm
Systolic pressure- ventricles contract- Aortic valve open – Peak pressure
Diastolic Pressure: ventricle relax- aortic valve closed- lowest pressure
MAP= - mean arterial pressure- pressure that pushes blood into tissues
MAP = diastolic + (pulse pressure/3)

16. Regulation Of BP 2. Peripheral resistance 3. Blood Volume
Cardiac Output = heart rate) X stroke volume
An average person has a resting heart rate of 70 beats/minute and a resting stroke volume of 70 mL/beat.
The total volume 5 liters (5000 mL). According to our calculations, the entire volume of blood within the circulatory sytem is pumped by the heart each minute (at rest).
During vigorous exercise, the cardiac output can increase up to 7 fold (35 liters/minute)
1 Cardiac Output
2. Peripheral resistance
3. Blood Volume

17. Starling's Law
Describes the relationship between end-diastolic volume and stroke volume.
The heart will pump out whatever volume is delivered to it. If the end-diastolic volume doubles then stroke volume will double

18. Baroreceptors- Neural Control

19. Hormonal Control

20. ADH and Aldosterone Aldosterone released by adrenal gland
Sodium reabsorbed in kidney
Water reabsorption by kidneys
Increased blood volume

21. Control of Heart Rate
SA node: controlled by sympathetic and parasympathetic nerve fibers. 1. At rest: the parasympathetic fibers release acetylcholine, which slow the pacemaker. 2. Activity (physical or emotional) sympathetic nerve fibers release norepinephrine and Epinephrine which acts to speed up the SA node thus increasing heart rate.

22. Blood Flow Capillaries- Blood Volume

24. How do Ace Inhibitors Work