Circulatory System 1

Question 1

Arteriosclerosis

Answer 1

generic term for conditions involving thickening and loss of elasticity of arterial walls. There are 3 major patterns, the most common of which is Atherosclerosis (esp. involved in coronary artery disease)

Question 2

Lumen

Answer 2

open space within a vessel where the fluid passes, like the open space in a straw or a garden hose. In RL: lumen contains blood, in Lab: lumen may be empty or filled with clotted blood.

Question 3

Tunica intima

Answer 3

Innermost
Single layer of flattened epithelia cells = Endothelium
Supported by delicate connective tissue
Capillaries consist of only this layer

Question 4

Three layers of Blood vessels

Answer 4

Tunica Intima, Tunica media, Tunica Adventitia (externa)

Question 5

Tunica media

Answer 5

Middle layer
Smooth muscle under autonomic innervation
Variable thickness and composition (arterty vs vein vs lymphatic ducts) (sometimes very thick or very thin)

Question 6

Tunica adventitia

Answer 6

Outermost

Comprised of connective tissue

Question 7

Atherosclerosis

Answer 7

Development of plaque lesions along the tunica intima
Lesions protrude into lumen
Obstructs flow
Weaken tunica media, leading to aneurysm
Plaques can rupture, leading to thrombosis
Thrombosis can partially or fully obstruct lumen, leading to ischemia downstream
In descending order, the most extensively involved vessels are the lower abdominal aorta, the coronary arteries, the popliteal arteries, the internal carotid arteries, and the vessels of the circle of Willis. Upper limb usually spared.

Plaques reduces diameter of vessel and reduce blood flow.

Plaque can also cause damage in the mucsle layer, it can then buldge out and rupture called an anyerism

Question 8

Three types of arteries

Answer 8

Large elastic, Medium muscular, Arterioles

Question 9

Large elastic arteries

Answer 9

Aka Conducting a.
Consist of multiple layers of elastic fibers in their walls
Allows expansion of vessel during systole
E.g., aorta, aa. originating from arch of aorta, pulmonary trunk + pulmonary aa

Question 10

Medium muscular arteries

Answer 10

Aka Distributing a.
Large component of circularly-arranged smooth muscle (thick tunica media meaning a lot of smooth muscle fibers)
Allows vasoconstriction: reduction in diameter of vessel to regulate blood flow
Pulsatile contractions of m. wall propels blood throughout body
E.g., most named aa. encountered in lab, femoral a.
Helps with temperature regulation

Question 11

Arterioles

Answer 11

Aka Small a. (need mircroscope to see)
Narrow lumen with thick muscular walls (regulate pressure of blood)
Tonus in walls regulates degree of filling of capillary beds and arterial pressure
E.g., typically unnamed, seen under magnification

Question 12

Capillaries

Answer 12

Simple tubes of tunica intima + supporting basement membrane, usually arranged in beds
Receive blood from arterioles (control flow to bed) and are drained by venules
Simple composition of endothelial tube allows exchange of materials with the intersitital/extracellular fluid
At arteriole end, pressure squeezes fluid out into intersitital space; at venule end, osmotic pressure drives fluid back into capillary

Lack tunica externa and media
In some regions (e.g., finger), some arterioles and venules are directly connected. This forms an ateriovenous anastomosis (AV shunt) that permits blood to pass directly from the arterial to the venous side, bypassing the capillary bed. AV shunts are important in temperature regulation.

Question 13

Three types of veins

Answer 13

Venules, Medium vv., Large vv.

Question 14

Venules

Answer 14

Drain capillary beds
Flow towards larger vv. that unite to form venous plexus (e.g., dorsal venous arch of foot)
Unnamed, require magnification to see

Question 15

Medium vv.

Answer 15

Receive blood from venous plexuses
May have valves, passive flaps that prevent backflow of blood; usually where blood is flowing opposite gravity
Often double or multiple, surrounding deep aa. (venae comitantes) bundled with it in fascial vascular sheath:
1) arterial blood serves to warm blood en route to heart,
2) arteriovenous pump, veins are flattened and compressed with each pulsation of the artery, thus squeezing blood back towards heart
- E.g., named superficial vv., named vv. that accompany medium aa. (femoral v.)

Question 16

Large vv.

Answer 16

Comprised of wide bundles of longitudinal smooth m. + well-developed tunica adventitia
E.g. SVC

Question 17

3 Major mechanisms to help blood return to the heart

Answer 17

Valves, especially common in medium vvv., Venae Comitantes, Musculovenous Pump

Question 18

Valves

Answer 18

Passive flaps of tissue within veins protruding into the lumen
Flow of blood towards heart pushes valve cusps open, allowing passage of blood
Backflow of blood (opposite direction) causes valve cusps to close, preventing blood from moving away from the heart

Question 19

Venae Comitantes

Answer 19

Accompanying veins
Often double or multiple, surrounding deep arteries
Usually a. + vv. are surrounded by fascia (a vascular sheath)
As a. pulses, veins are squeezed, which propels blood back towards heart
This arrangement also serves thermal function by warming the venous blood through close proximity to the arterial blood.
Viens will hug onto arteries surrounded by vascualr sheath. As blood pulsates through the artery, it generates force against the vein to push blood upward back towards the heart.

Question 20

Musculovenous Pump

Answer 20

Especially in limbs, superficial vv. shunt blood into deep veins
Deep veins positioned within muscle compartments wrapped in dense fascia
As muscle contracts, fibers shorten but m. bulge in outwards direction is limited by fascia, thereby constricting veins.
Propels blood towards heart, effectively ‘milking’ venous blood.

Question 21

Portal Venous Systems

Answer 21

A venous system that links two (2) capillary beds

Question 22

Anastomoses

Answer 22

Communications between multiple branches of an artery

Question 23

Three mechanisms of Vascular Growth

Answer 23

Vasculogenesis, Angiogenesis (neovascularization), Arteriogenesis

Question 24

Vasculogenesis

Answer 24

Formation of blood vessels during embryogenesis

Question 25

Angiogenesis

Answer 25

growth of new blood vessels from preexisting blood vessels (New vessel formation in mature organism)

Question 26

Arteriogenesis

Answer 26

Remodeling of existing arteries
Response to chronic changes
in pressure or flow

Question 27

Functions of the Lymphatic system

Answer 27

Keep interstitial fluid at constant level by draining excess tissue fluid + plasma proteins (not all fluid in extracellular spaces is resorbed by capillaries, and plasma proteins generally cannot pass through capillaries)
Removes debris stemming from cellular decomposition + infection
Malfunction leads to excess of intersitital fluid, causing edema (swelling)
Immunological role in infection response
Absorption and transport of dietary fats (discuss more in abdomen)

Question 28

Three parts of the lymphatic system

Answer 28

Lymphatic Plexuses, Lymphatic vessels, Lymph nodes

Question 29

Lymphatic Plexuses

Answer 29

Capillaries originate in extracellular space
Tubes of endothelium w/out basement membrane; allows excess tissue fluid, plasma proteins, bacteria, cellular debris, whole cells (e.g. lymphocytes) to enter capillaries
This fluid is called lymph, clear-to-yellowish watery fluid

Question 30

Lymphatic vessels

Answer 30

Network of thin-walled vessels, superficial and deep
Numerous valves
Return lymph to venous circulation via two large lymphatic trunks
Rt. Lymphatic duct  drains Upper Right Quadrant lymph into Rt. IJV and Rt. Subclavian v.
Thoracic duct  drains rest of body lymph into Lt. IJV and Lt. Subclavian v.
- Some lymphatic vessels also communicate directly with veins throughout the body (lymphaticovenous anastomoses)

Question 31

Lymph nodes

Answer 31

Small masses of lymphatic tissue intermittently positioned along lymphatic vessels
Lymph is filtered by passing through the nodes before returning to venous circulation