I). Description

• Arteries carry blood away from the heart
• Veins carry blood to the heart

II). Vessel structure

A). tunics

1). Tunica interna

Endothelium

2). Tunica media

smooth muscle

3). Tunica externa

Collagen fibers

B). Vasa Vasorum: blood vessels

C). Capillaries are composed of only endothelium.

III). Arterial System

A). Elastic (Conducting) Arteries (2.5 cm à 1.0 cm)

 aorta and the major branches.

Characteristics:

1). low resistance

2). absorb the changes in blood pressure.

3). limited vasoconstriction

4). no pulsing

B). Muscular (Distributing) Arteries (1cm à 3mm)

Characteristics

1). thick muscle

2). less elastic tissue

3). dilation and constriction

4). pulses

 

C). Arterioles (.33mm à 10: m)

 Determine the blood flow into the capillary beds.

Pericyte Cells:

IV). Capillaries

A). Function

1). access to tissues.

2). exchange of material

3). waste removal

B). Structure

1).thin tunica interna.

2). "Openings to allow material to pass"

i).   tight junctions

ii).  intercellular cleft:

iii). fenestrations:

C). Types of Capillaries

1). Continuous Capillaries

	intercellular clefts.
	muscles and skin & forms the blood brain border

2). Fenestrated Capillaries

•  pores or fenestrations covered in a membrane.
• intestine, endocrine organs, nephrons.

3). Sinusoidal Capillaries

	liver, bone marrow, lymphatic tissue, endocrine organs
	Large intercellular clefts

D). Capillary Beds

1). Shunt

2). True Capillaries

V). Venous System

A). Venules

B). Veins

1). Structure

i).  3  tunics.

ii). little smooth muscle

iii). larger lumens and thinner walls

iv). blood pressure low

2). Adaptations to low blood pressure

i).  little resistance

ii). venous valves that prevent backflow

 

VI). Vascular Anastomoses