Histo of Blood Vessels

Question 1

3 layers of blood vessels

Answer 1

Tunica intima
Tunica media
Tunica adventitia

Question 2

Tunica intima

Answer 2

Innermost layer
Lined with endothelium
Basement membrane
Lamina propria (CT)

Question 3

Tunica media

Answer 3

Middle layer
Smooth muscle cells
Connective tissue with collagen and elastic fibers
SM cells secrete the ECM

Question 4

Tunica adventitia

Answer 4

Outermost layer
Mostly loose CT
Has blood vessels, nerves, immune cells and fibroblasts

Question 5

Endothelial cells

Answer 5

Simple squamous epithelial cells that line the blood vessels

Aligned with long axes in the direction of blood flow

Question 6

Large (elastic) arteries

Answer 6

Large vessels that move blood along the arterial tree
Operate under high pressure
Elastic lamellae in arterial wall compensate for intermittent pressure changes

Question 7

Medium (muscular arteries)

Answer 7

Distributing arteries
Thick tunica media
Most of the named arteries in the body
Prominent internal and external elastic membranes
Elastic fibers not lamellae

Question 8

Arterioles

Answer 8

Smaller arteries that regulate blood flow to the capillary networks
Vasodilate or vasoconstrict
Control blood flow (and regulate BP)
Large amount of smooth muscle relative to the size of vessel

Question 9

Key features of arterial walls

Answer 9

Thick vessel wall compared to lumen size
Tunica media is the most prominent layer
Tunica adventitia is approx the same size as the media

Question 10

Atherosclerosis pathogenesis

Answer 10

Endothelium injury
LDLs penetrate, accumulate, and oxidize beneath endothelium
Oxidized LDL stimulates endothelium to secrete chemokines that attract monocytes
Monocytes –> macrophages that phagocytose the oxLDLs and become large, lipid laden foam cells
Foam cells accumulate and form fatty streaks = earliest stage of plaque formation
Migration of SMC from media to intima marks the progression from a fatty streak to a more mature plaque (core and fibrous cap)

Question 11

Mild plaques

Answer 11

Thickened intimal layer
Core contains lipids, macrophage foam cells, SMC
Surrounding plaque has a fibrous cap with SMC secreting ECM

Question 12

Pericytes

Answer 12

Often associated with capillaries

Supportive and contractile

Question 13

3 types of capillaries

Answer 13

Continuous
Fenestrated
Discontinuous

Question 14

Continuous capillaries

Answer 14

Most common
Single, continuous endothelial layer with tight junctions
Muscle, lung, CNS, blood brain/thymus/gas barriers
Transport has to go through the cells

Question 15

Fenestrated capillaries

Answer 15

Fenestrations in capillary wall to facilitate gas exchange an movement of small molecules
Endocrine glands, gallbladder, kidney, intestinal tract

Question 16

Discontinuous capillaries

Answer 16

Sinusoids
Larger, discontinuous, irregularly shaped
No basement membrane
Liver, spleen, bone marrow

Question 17

Large veins

Answer 17

High capacitance vessels
Hold large volumes of blood
Thin walls and large lumens
Intimal-medial boundary is hard to distinguish, contains circular smooth muscle
Prominent adventitia with longitudinal smooth muscle
Vasa vasorum

Question 18

Medium veins

Answer 18

Travel with medium arteries
Thin walls and large lumens
Valves prevent retrograde movement of blood
Has vasa vasorum
Prominent adventitia, hard to tell between intima and media

Question 19

Venules

Answer 19

Receive blood from capillaries

Question 20

3 ways blood gets back to the heart

Answer 20

Skeletal muscle pump (and valves)
Venoconstriction
Respiratory pump

Question 21

3 functions of the lymphatic system

Answer 21

Return of excess filtered fluid and protein
Defense against disease
Transport of absorbed fat