1. Ch. 19 The Cardiovascular System: Blood Vessels

2. I. OVERVIEW OF BLOOD VESSEL STRUCTURE AND FUNCTION
OVERVIEW: Parts & Function
Arteries and arterioles:
Capillaries
Veins and Venules
TOPICS
Histology
Gross Anatomy
Physiology
Blood Flow
Blood Pressure
Disorders
Specific Blood Vessels & Identification
Arteries
Capillaries
Veins

3. I. Histology of Blood Vessel Walls– 3 layers1.
Tunica intima
• Endothelium
Valve
• Subendothelial layer
Internal elastic lamina 2.
Tunica media
(smooth muscle and
elastic fibers)
External elastic lamina 3.
Tunica externa
(collagen fibers)
Vasa Vasorum
Lumen
Vein
Lumen
Artery
Capillary
network
Basement membrane
Vasodilation & Vasoconstriction
Endothelial cells
(b)
Capillary
Figure 19.1b

4. * a) Endothelium & Basement membrane Function: In veins:
1. Tunica Intima =
* a) Endothelium & Basement membrane
Function:
In veins:
* b) Subendothelial Layer– Areolar C.T w/ mostly elastic fibers
c) Internal Elastic Lamina (membrane) =
Type of vessels:
Artery
Endothelium
SubEndo.
Internal E.L.
Vein
Endothelium
SubEndo.

5. Thickest layer in arteries * a) smooth muscle:
2. Tunica Media =
Thickest layer in arteries
* a) smooth muscle:
* b) Connective tissue:
Appears wavy
c) External Elastic Lamina =
Vessels: only large arteries
Location: between T.M. & T.E.
3. Tunica Externa (adventitia) =
Thickest layer in veins
Outer border unclear
Artery
Tunica M.
Smooth Muscle
External E.L
Tunica Externa.
Vein
Tunica M.
Smooth Muscle
Tunica Ex.

6. Tunica Intima
Endothelium &
Internal Elastic Lamina
Tunica Media
Tunica
Externa
Tunica Intima
Endothelium
Tunica Media
Tunica
Externa

7. B. Arterial System Elasticity = Compliance 1. Elastic Artery
Resistance to Flow:
Pressure:
2. Muscular Artery
Smooth muscle:
Lumen diameter:
3. Arteriole
Number & Size:
resistance to flow:
Flow to capillaries: controlled by

8. 4. Vascular Anastomoses =
Arterial anastomoses =
Organs: Joints, abdominal organs, brain, and heart
Venous anastomoses = very common
BRAIN: Arterial Anastomoses =
Circle of Willis
- Internal Carotid & Vertebral Arteries

9. C. Capillaries 5-10 µm diameter
Basic Structure
Endothelium:
Some scattered smooth muscle
Function:
Three Types
Continuous capillaries =
Prevalence:
tight junctions:
Brain:

10. 2. Fenestrated capillaries Tight Junctions: Fenestrations Locations:
C. Capillaries …
2. Fenestrated capillaries
Tight Junctions:
Fenestrations
Locations:
3. Sinusoidal capillaries (sinusoids)
Flattened
Leakiest:
Pass large molecules and blood cells

11. 4. Capillary Beds
a) Metarteriole & Thourghfare Channel = Vascular Shunt
Location:
Attach Capillary beds attached ( capillaries)
b) Precapillary Spincters =
Normally closed, but open to allow O2 & nutrients
c) Function:
Thoroughfare Channel
Metarteriole
Figure 11.11a

12. Bypassed Capillary Beds
Figure 11.11b

13. D. Venous System 1. Venules 2. Veins Overall size & Lumen size:
Pressure is?
Thin walls
Capacitance Vessels: blood reservoirs
Venous Valves: foldsn in largest V
Function:
Venous Sinuses: flattened with only endothelium

14. C. Venous System … - Differences Between Vessels