1. CARDIOVASCULAR SYSTEM
Blood Vessels and Blood Pressure
Chapter 15
Topics 4 - 7

2. Differences Between the Vessels
Arteries  arterioles  capillaries  venules  veins
Arteries - carry blood away from heart
Round Cross Section
Tough and Elastic
Elastic recoil helps keep blood flowing
3 Layers:
Tunica Adventitia – Outer
CT to connect arteries in place
Tunica Media – middle
Smooth muscle
Vasoconstriction  sympathetic N.S.
Vasodilation  inhibition of sympathetic NS
Elastic CT – pulse
Tunica Intima – inner endothelium
Needs to be smooth
DIAGRAM

3. Differences Between the Vessels
Arterioles – small arteries
Precapillary sphincters – open and close capillary beds
Metaterioles
Major part of vasodilation and vasoconstriction
Veins – carry blood toward heart (atria)
3 layers
Tunica adventitia
Tunica Media – less developed
Tunica Intima – one way valves
Blood Resevoir
Skeletal Muscles help move blood
Venules – small veins
DIAGRAM

4. CAPILLARIES Smallest; walls one cell thick
Largest total cross sectional area
Connect arteriole and venous systems
Capillary permeability varies
Muscle tissue cap small
Gland, intestinal cap. Larger
Liver, spleen and bone marrow cap. Largest  sinusoids
Capillary Arrangement
Nearly every tissue has associated cap. Bed
High metabolic  extensive cap. Bed
Can be shut off or opened up
Precapillary sphincters
DIAGRAM

5. CAPILLARIES Only place for exchange Diffusion
At Tissues: O2, nutrients out; CO2, wastes in
At alveoli (lungs): CO2 out; O2 in
Sm. Intestines: Nutrients in
Lipid soluble and small molecules diffuse easily
Plasma Proteins remain in blood
Filtration – hydrostatic pressure
Pressure decreases as distance increases
Filtration greater at arteriole end
Water is lost
Movement depends on osmotic and hydrostatic pressures
Lymph system returns fluid
DIAGRAM

6. Arteries VS Veins

7. Capillary Structure

8. Fluid Pressure at Capillaries