1. Blood Vessels & Circulation

2. Three Types of Blood Vessels
1. Arteries
Take blood away from heart
Usually oxygenated
Branch repeatedly
Arterioles
2. Capillaries
One cell thick
Billions present
Large surface area for nutrient exchange

3. Three Types of Blood Vessels
3. Veins
Take blood to heart
Usually deoxygenated
Converge
Venules

5. Tunics – Layers of Blood Vessels
Tunica intima
Endothelium
Lines vessels
Tunica media
Smooth muscle/elastic tissue
Changes vessel diameter
Vasodilation
Vasoconstriction
Tunica externa
Connective tissue covering

6. What structural differences do you see?

7. Structural Differences - Arteries
Very thick tunica media (Why?)

8. Structural Differences - Veins
Thinner walls, larger lumens
Valves (Why?)
Three factors aiding in venous return
Valves
Respiratory pump
Skeletal muscles

9. Structural Differences - Capillaries
Tunica intima is only one cell thick (Why?)
Capillary beds
True capillaries
Vascular shunts
Microcirculation

10. Capillary Exchange
Substances diffuse through interstitial fluid from high to low concentration

11. Homeostatic Imbalances
Varicose Veins

12. Homeostatic Imbalances
Atherosclerosis & arteriosclerosis

13. Hydrostatic & Osmotic Pressure
Hydrostatic Pressure – forces fluid out at arteries
Osmotic Pressure – draws fluid back in at veins

14. Vital Signs Respiratory Rate Body Temperature Blood Pressure
Pulse – pressure wave of blood; measure at Pressure Points

15. Blood Pressure

16. Measuring Blood Pressure
Two measurements using a sphygmomanometer:
Systolic – Pressure at peak of ventricular contraction
Diastolic – Pressure when ventricles relax

17. Blood Pressure Gradient
Highest in aorta
Lowest in vena cava

18. Measuring Blood Pressure
Sounds of Korotkoff
Systolic pressure – 1st tapping sound when blood squirts through constricted artery
Diastolic pressure – sounds disappear, blood flows freely
Ex. A normal reading of 120/75 mmHg
120 systolic pressure/75 diastolic pressure

19. Blood Pressure (BP) BP = CO x PR
CO = cardiac output = heart rate x stroke volume
PR = peripheral resistance
The amount of friction encountered by the blood as it flows through the blood vessel

20. Factors Affecting Cardiac Output

21. Factors Affecting Peripheral Resistance
Viscosity – fairly constant in a healthy person
What could cause an increased viscosity?

22. Factors Affecting Peripheral Resistance
Neural factors
Vasoconstriction
Vasodilation

23. Factors Affecting Peripheral Resistance
Renal factors
The kidney retains or releases water in urine to regulate BP levels
When BP is low:
Kidneys release renin to cause vasoconstriction.
Adrenal glands release mineralocorticoids to retain salt (causing less water lost as urine)

24. Factors Affecting Peripheral Resistance
Chemicals
Nicotine - BP by vasoconstriction… and then you DIE!
Alcohol – BP by vasodilation
Epinephrine – HR and BP

25. Factors Affecting Peripheral Resistance
Diet and Exercise
High salt, saturated fats, cholesterol = BP
Each extra pound of fat, requires miles of additional blood vessels = BP

26. Homeostatic Imbalance
Hypertension – sustained high blood pressure (140/90 or greater)