Chapter 21 Lecture 5

Question 1

The Cardiovascular System involves:

Answer 1

Structure and function of blood vessels (Pt. 1)
Hemodynamics
forces involved in circulating blood (Pt. 2)
Major circulatory routes (Pt. 3)

Question 2

Artery:

Answer 2

These muscular, elastic vessels carry blood under pressure from the heart. They branch many times before they become arterioles

Question 3

Arterioles

Answer 3

Microscopic, thin-walled but still muscular vessels that regulate blood flow into the Capillaries

Question 4

Capillaries

Answer 4

Single layer of epithelial cells that allow exchange of fluids, gasses, and nutrients in tissues. They then pass on to Venuoles

Question 5

Venuoles

Answer 5

Thin-walled vessels that intersect others to begin returning blood to the heart. Eventually they merge to become larger veins

Question 6

Veins

Answer 6

Similar structure to arteries, but much thinner walls, wider diameter, and less elastic

Question 7

Inner layer =

Answer 7

tunica interna. Very thin inner lining in contact with blood. Three layers:

1. squamous cell epithelium
2. epithelial basement membrane
3. internal elastic lamina

Question 8

Middle Layer =

Answer 8

Muscular, elastic layer that varies considerably in thickness between the vessel types. Composition:

1. smooth muscle cells
2. elastic fibers

Question 9

Outer layer =

Answer 9

tunica externa.  Three primary elements:
1. external elastic lamina
2. nerves
3. vascular system 
4/ connections/anchorage

Question 10

Sympathetic Innervation:

Answer 10

Vascular smooth muscle is innervated by sympathetic nervous system

Question 11

increase in stimulation causes

Answer 11

muscle contraction or vasoconstriction

Question 12

injury to artery or arteriole causes

Answer 12

muscle contraction reducing blood loss (vasospasm)

Question 13

decrease in stimulation or presence of certain chemicals causes

Answer 13

vasodilation

Question 14

Structure of Arteries:

Answer 14

thick-walled elastic, muscular vessels that take blood from the heart under pressure

Question 15

Two types of arteries:

Answer 15

1. Elastic (connecting) arteries: thick tunica media and both elastic lamina. Ex.: pulmonary, aorta. Stretches, then pushes blood away from the heart.
2. Muscular (distributing) arteries: thick muscle, low elastic, high collagen = regulation of blood pressure & direction, but do not aid in propelling flow.

Question 16

Structure of Arterioles

Answer 16

Small arteries delivering blood to capillaries

Metarterioles form branches into capillary bed

Question 17

Structure of Capillaries:

Answer 17

endothelial cell layer only; no tunica media or externa. Desmosomes, tight jcns, but also intercellular clefts between cells.

Question 18

Types of capillaries:

Answer 18

• continuous: complete basement membrane. Most capillaries.
• fenestrated: pores in basement membrane. Increase fluid exchange in kidneys, sm. intestine, and choroid plexes.
• sinusoid: gaps in basement membrane. Allow cell crossing in bone marrow, liver, spleen.

Question 19

Structures of Venules:

Answer 19

Essentially the reverse of arterioles, but no bordering muscular sphincter.

Question 20

Two types of venules:

Answer 20

1. post capillary venule: larger than capillary but very loose intercellular endothelial connections allow continued exchange of nutrients, gasses, wastes, etc. No sphincter.
2. muscular venules: muscle fibers surround thickened endothelium; exchange no longer occurs

Question 21

Structure of Veins:

Answer 21

Like arteries, 3 tunics, but
tunica interna and tunica media are much thinner
elastic layers missing
blood with little pressure
veins in extremities have valves to aid return
more veins than arteries, often with interconnected superficial and deep or paired, connected veins following artery

Question 22

venous sinuses =

Answer 22

no tunica media & externa; bordered by connective tissue.

Question 23

Vein valve function:

Answer 23

movement against gravity

Question 24

Varicose Veins:

Answer 24

• Twisted, dilated superficial veins (caused by leaky venous valves, allow backflow and pooling)
• Deeper veins not susceptible because of support of surrounding muscles

Question 25

Capillary Exchange

Answer 25

1.Movement of materials in and out of a capillary
2.Oxygen, carbon dioxide, nutrients,
and metabolic wastes diffuse
between the blood and interstitial
fluid along concentration gradients
3. 3 Mechanisms

Question 26

3 mechanisms

Answer 26

Diffusion
Transcytosis
Filtration and Reabsorption

Question 27

Diffusion

Answer 27

• Most important mechanism
• Substances move down concentration gradient
• Lipid soluble substances
• Insoluble substances

Question 28

Transcytosis

Answer 28

Passage of material across endothelium in tiny vesicles by endocytosis and exocytosis

Question 29

Bulk Flow: Filtration and Reabsorption

Answer 29

• Movement of large amount of dissolved or suspended material in same direction
• Move in response to pressure - from area of high pressure to area of low
• Regulates relative volumes of blood & interstitial fluid
• Comprised of: filtration (movement of material into interstitial fluid) + reabsorption