packet 4

Question 1

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

Answer 1

artery

Question 2

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

Answer 2

arterioles

Question 3

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

Answer 3

capillaries

Question 4

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

Answer 4

venuoles

Question 5

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

Answer 5

veins

Question 6

tunica interna. Very thin inner lining in contact with blood.

Answer 6

inner layer

Question 7

three layers of inner layer

Answer 7

squamous cell epithelium
epithelial basement membrane
internal elastic lamina

Question 8

“endothelium” that lines the entire circulatory system. Cells help in regulation of vessel contraction, protection of cells, mediating capillary permeability and preventing permeability elsewhere.

Answer 8

squamous cell epithelium

Question 9

Tough acellular layer that anchors endothelium to connective tissues. Additional barrier to diffusion.

Answer 9

epithelial basement membrane

Question 10

Porous, elastic fibers

Answer 10

internal elastic lamine

Question 11

*thin, tough, flexible layer to contain blood and mediate exchange with surrounding tissues.

Answer 11

inner layer (tunica internal)

Question 12

tunica media. Muscular, elastic layer that varies considerably in thickness between the vessel types. Composition: smooth muscle, elastic fibers

Answer 12

middle layer

Question 13

encircle vessel to regulate diameter, essential to direct blood flow and modify blood pressure.

Answer 13

smooth muscle cells

Question 14

provide flexible support within the muscular layer.

Answer 14

elastic fiber

Question 15

essential to direct blood flow and provide structural strength and flexibility.

Answer 15

middle layer (tunica media)

Question 16

tunica externa. Three primary elements:
elastic and collagen fibers of the external elastic lamina. Again = tough flexibility.
nerves to interact with and regulate smooth muscles of tunica media
vascular system (vasa vasorum) to nourish cells in larger vessels (e.g., aorta, vena cavae, etc.)
connections/anchorage to surrounding tissues.
* Outer protective (rip, stretch, feed) layer.

Answer 16

outer layer

Question 17

Vascular smooth muscle is innervated by sympathetic nervous system
increase in stimulation causes muscle contraction or vasoconstriction
decreases diameter of vessel
injury to artery or arteriole causes muscle contraction reducing blood loss (vasospasm)
decrease in stimulation or presence of certain chemicals causes vasodilation
increases diameter of vessel
nitric oxide, K+, H+ and lactic acid cause vasodilation

Answer 17

sympathetic innervation

Question 18

Structure: thick-walled elastic, muscular vessels that take blood from the heart under pressure.
Two types: elastic, musclular

Answer 18

arteries

Question 19

thick tunica media and both elastic lamina. Ex.: pulmonary, aorta. Stretches, then pushes blood away from the heart.

Answer 19

elastic (connecting) arteries

Question 20

thick muscle, low elastic, high collagen = regulation of blood pressure & direction, but do not aid in propelling flow.

Answer 20

muscular (distributing) arteries

Question 21

Small arteries delivering blood to capillaries
tunica media containing few layers of muscle
Metarterioles form branches into capillary bed
to bypass capillary bed, precapillary sphincters close & blood flows out of bed in thoroughfare channel
vasomotion is intermittent contraction & relaxation of sphincters that allow filling of capillary bed 5-10 times/minute

Answer 21

arterioles

Question 22

Structure: endothelial cell layer only; no tunica media or externa. Desmosomes, tight jcns, but also intercellular clefts between cells.
Types via basement membrane: continous, fenestrated, sinusoid

Answer 22

Capillaries

Question 23

complete basement membrane. Most capillaries.

Answer 23

continous

Question 24

pores in basement membrane. Increase fluid exchange in kidneys, sm. intestine, and choroid plexes.

Answer 24

fenestrated

Question 25

gaps in basement membrane. Allow cell crossing in bone marrow, liver, spleen.

Answer 25

sinusoid

Question 26

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

Answer 26

venules

Question 27

larger than capillary but very loose intercellular endothelial connections allow continued exchange of nutrients, gasses, wastes, etc. No sphincter.

Answer 27

postcapillary venule

Question 28

muscle fibers surround thickened endothelium; exchange no longer occurs

Answer 28

muscular venules

Question 29

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 venous sinuses = no tunica media & externa; bordered by connective tissue.

Answer 29

veins

Question 30

Twisted, dilated superficial veins caused by leaky venous valves congenital or mechanically stressed from prolonged standing or pregnancy allow backflow and pooling of blood extra pressure forces fluids into surrounding tissues nearby tissue is inflamed and tender Deeper veins not susceptible because of support of surrounding muscles

Answer 30

varicose veins

Question 31

3 mechanisms of capillary exchange | MICRO ESSAY

Answer 31

Diffusion Transcytosis Filtration and Reabsorption

Question 32

``` Movement of materials in and out of a capillary Oxygen, carbon dioxide, nutrients, and metabolic wastes diffuse between the blood and interstitial fluid along concentration gradients Oxygen and nutrients pass from the blood to tissues Carbon dioxide and metabolic wastes pass from tissues to the blood ```

Answer 32

capillary exchange

Question 33

Most important mechanism Substances move down concentration gradient through lipid bilayer, fenestrations or intercellular clefts Lipid soluble substance Insoluble substance

Answer 33

diffusion

Question 34

steroid hormones, O2 and CO2 diffuse easily

Answer 34

lipid soluble substance

Question 35

``` glucose and electrolytes must pass through channels, fenestrations, or intercellular clefts ```

Answer 35

insoluble substance

Question 36

Passage of material across endothelium in tiny vesicles by endocytosis and exocytosis large, lipid-insoluble molecules such as insulin or maternal antibodies passing through placental circulation to fetus

Answer 36

transcytosis

Question 37

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 (movement from interstitial fluid into capillaries)

Answer 37

Bulk Flow: Filtration and Reabsorption