Anatomy of Blood Vessels

Question 1

What are arteries known for doing?

Answer 1

they carry blood away from the heart

Question 2

What are the (3) main tunics (layers) of the artery’s and vein’s?

Answer 2

Tunic intima (interna) -the deepest layer, lined with "simple squamous epithelium" aka endothelium, Subendothelial layer and internal elastic membrane, (lamina) thin scale.
Tunica media- the middle layer, usually the thickest, contains smooth muscle and an external membrane, (lamina) thin scale.
Tunica externa - aka (adventitia), outermost layer, composed of mostly collagen fibers and vasa vasorum. (vessels of the vessel)

Question 3

what is lumen?

Answer 3

the hollow center that blood runs through

Question 4

Can a Neuronal stimulus change the diameter of blood vessels?

Answer 4

Yes, it stimulates blood vessels by making smooth muscle to contract.

Question 5

What is vasoconstriction and vasodialation?

Answer 5

Vasoconstriction- decreases blood vessel diameter due to sympathetic stimulation and makes contraction of the smooth muscle. Vasodiation-an increase in blood vessel diameter due to smooth muscle relaxing.

Question 6

Describe Elastic (conducting) arteries

Answer 6

They are the largest in diameter because, they carry large volumes of blood. They handle high pressure well, they are made out of elastic fibers and function as a pressure reservoir.

Question 7

Describe Muscular (distributing) arteries

Answer 7

Medium diameter, muscular because they have smooth muscle and fewer elastic fibers, they can adjust their diameter to a great range to meet the needs of tissue or organs supply.

Question 8

Describe Arterioles

Answer 8

Small artery, still visible to the naked eye, they get smaller as they merge with capillaries and have less smooth muscle than arteries.

Question 9

How would you describe Capillaries and their function ?

Answer 9

They account for the microcirculation of blood and function in the exchange of gases, wastes and nutrients. Tunica intima only (made up ob endothelium and basement membrane). Arterioles , act as “valves” and close the flow into a capillary bed when they constrict.

Question 10

What is differnt about Microcirculation through a special (mesenteric) capillary beds?

Answer 10

Metateriole- connects arteriole to the capillary bed and connects venule via throughfare channel. Metaarteriole has smooth muscle close to arteriole to regulate flow.

Question 11

What part of metearteriole merges with the venule?

Answer 11

the throughfare channel portion of the metarteriole merges with the venule.

Question 12

What is a vascular shunt?

Answer 12

metarteriole + throughfare channel = vascular shunt

Question 13

What are true capillaries?

Answer 13

true capillaries are a part of the capillary bed and not on the direct flow. They have papillary sphincters that is a ring of smooth muscle to control the flow of blood.

Question 14

Vasomotion

Answer 14

is contraction and relaxation of smooth muscle in the sphincter.

Question 15

Name (3) types of true Capillaries

Answer 15

Continuous capillary- when the endothelium is an uniterrrupted lining, no pores and intercellular clefts are present.
Fenestrated capillaries- Pores (microscopic holes) are present, very commonly found in small intestine and kidneys.
Sinusoids ( sinusodial capillaries)- wide diameter capillaries, large intercellular clefts usually fenestrated, and are very leaky. Basement membrane is not complete and they are found primarily in the liver and the spleen.

Question 16

Where are venules formed on a capillary?

Answer 16

they form on the other side of cappilaries from throughfare channel, very porse, like fenestrated capillries. They are similar to arterioles and there is much less smooth muscle than veins, especially if they are close to a capillary.

Question 17

characteristics of veins

Answer 17

no elastic laminates, carry blood toward the heart, the pressure in veins is much lower so they dont need to be as elastic or as muscular as arteries, they contain valves that are extensions of the tunica interna and they allo blood to pool.

Question 18

Venous (vascular) Sinus

Answer 18

a vein with a very thin endothelium and no smooth muscle, they contain dense connective tissue intstead of a tunica media or tunica externa. Example: coronary sinus and intracranial sinuses.

Question 19

Anastomoses

Answer 19

the joining of two or more arteries that provide for the blood flow or collateral circulation. they can occur between arterioles and venules.

Question 20

Blood distrabution (reservoirs at rest)

Answer 20

60% systeminc veins and veneules,15% systemic arteries and arterioles, 12% pulmonary circuit, 8% heart, 5% systemic capillaries.

Question 21

What is happening with venoconstriction?

Answer 21

Venoconstriction- involves the constriction of veins which diverts blood where it is needed, skeletal muscle during exercise, it also occurs during extreme blood loss to maintain blood pressure.

Question 22

what are the (3) mechanisms that support the transportation in and around the capillaries?

Answer 22

Diffusion- small, lipid soluble molecules can pass through plasma membrane easily, all transportation is with the concentration gradient.
transcytosis- (aka vesicular transport) includes endocytosis, exocytosis and pinocytosis.
bulk flow- (includes filtration and reabsorption)-Large amounts of fluid are being transported due to pressure diffrences.

Question 23

what is “Filtration” referring to capillary exchanges and “Reabsorption”?

Answer 23

filteration-Is the movement from capillaries to interstital fluid.
Reabsorption- is the movement from interstital fluid to the capillaries.

Question 24

What are two factors that affect blood flow?

Answer 24

Pressure diffrence (flow from high to low) and Resistance to flow.

Question 25

Circulation and Circulation time?

Answer 25

Circulation= Volume of blood flow per minute ml/min and Circulation time= round trip from right atrium to right atrium. (usually one minute)