Chapter 11 - Circulatory System

Question 1

Function of the circulatory system

Answer 1

• propels blood to all tissues/organs of the body - heart and blood vessels
• returns tissue fluid to the blood through lymphatic vessles to reach fluid homeostasis

Question 2

What are the types of tissues present?

Answer 2

• squamous epithelium - endothelium
• connective tissue
• smooth muscle
• blood cells

Question 3

Fluid movement in the tissues

Answer 3

• fluid moves into tissues from capillary beds
• most returns to circulatory system via lymphatic vessels

Question 4

Microvasculature vs. microvasculature

Answer 4

• macro - elastic, muscle arteries, muscular veins, large arterioles
• micro - arterioles, capillaries, venules

Question 5

General properties of Capillaries

Answer 5

• only have tunica intima
• adapted for ga/metabolite exchange - transport occurs by diffusion, pinocytosis, movement of molecules/cells through intercellular clefts of fenestrations
• RBCs pass through one at a time
• several diff types of capillaries to permit diff levels of exchange with the surrounding tissue

Question 6

Continuous capillaries

Answer 6

tightest

skin, muscle, lung, CNS

continuous basal lamina

tight junctions

Question 7

Fenestrated capillaries

Answer 7

middle level of tightness

have pored called fenestrations - allow for greater permeability than continuous capillaries

found wherever active capillary absorption occurs or filtrate formation takes place

kidneys, small intestines, endocrine

Question 8

Sinusoidal capillaries

Answer 8

greatest permability

incomplete basal lamina and large fenestrations

leaky - proteins and cells can pass through

liver, spleen, lymph nodes, bone marrow, adrenal glands

Question 9

All blood vessels have 3 layers, except which kind? What are those three layers?

Answer 9

• capillaries only have two
• tunica intima
• tunica media
• tunica adventitia

Question 10

Tunica intima

Answer 10

innermost layer, in direct contact w/ blood

endothelium composed of squamous epithelium

basal lamina underlies endothelium in vessels >1 mm indiameter

Question 11

Tunica media

Answer 11

middle layer

circular layer made of smooth muscle (the larger the vessel, the more smooth muscle)

collagen and elastic fibers encircle the vessel lumen (larger vessels will have more)

Question 12

Tunica adventitia

Answer 12

outermost layer of CT

collagen fibers that are oriented longitudinally

elastic fibers

in very large vessels, may contain small blood vessels

Question 13

What are lumen?

Answer 13

interior of vessels

Question 14

What are the different types of arteries?

Answer 14

• carry blood away from the heart
• elastic arteries, muscular arteries, arterioles

Question 15

Elastic arteries

Answer 15

conducting arteries - those that are nearest the heart are thick walled (aorta)

extensive elastic fibers in tunic media that withstand and smooth out large pressure changes

in charge of blood pressure as the ventricle squeezes and relaxes

some of the largest lumens

Question 16

Muscular arteries

Answer 16

internal elastic lamina is a hallmark of these

distribution arteries

more smooth muscle in tunica media than elastic arteries

prominent internal elastic lamina at innermost part of tunica media

Question 17

Arterioles

Answer 17

regulate blood flow to capillary beds

precapillary sphincters at the junction of arterioles with capillary beds (contraction/relaxation is regulated by vasoconstrictors/dilators)

have anywhere from 1-3 layers

relatively thin tunica adventitia

in general, smooth muscle tone is very important to regulate blood pressure

Question 18

Veins

Answer 18

return blood to the heart

not as much elastic tissue or muscle - low pressure and low resistance

volume reservoirs - 60-70% of blood volume is in the venous system

typically have thinner walls and larger lumens

adventitia is thicker in veins than arteries, is the most developed tunic in veins

relative thin tunica media - lumen may appear collapsed

Question 19

Venules

Answer 19

formed when capillary beds unite

consists of endothelium surrounded by pericytes (minimal tunica adventitia)

larger venules have 1-2 layers of smooth muscle (tunica media)

Question 20

Hypertension

Answer 20

long term, elevated BP is a risk factor for stroke

BP setpoint determined by smooth muscle tone in arterioles

also influenced by atherosclerosis

Question 21

Atherosclerosis

Answer 21

accumulation of fatty deposits in tunica media of arteries, proliferation of smooth muscle in tunica media also occurs

normal part of aging

occurs more frequently in persons w elevated cholesterol and plasma lipids

most dangerous when plaques form in coronary and carotid arteries

increases platelet aggregation

gradual occlusion of artiers

aspirin and Plavix decreased formation by decreasing platelet aggregation

Question 22

What occurs during atherosclerosis?

Answer 22

1- ciruclating monocytes take up lipids, then are called foam cells
2- foam cells adhere to tunica intima and release growth factors
- stimulates further lipid uptake and proliferation of smooth muscle in tunica media that creates plaque
- endothelial cells also take up lipids
- creates abnormality in wall, alerting platelets

Question 23

Arteriosclerosis

Answer 23

hardening of arteries that occurs when fatty deposits become calcified (atherosclerosis)

as it progresses, smooth muscle in tunica media begins to die and elastic fibers are degraded, replaced by scar tissue

calcium salts accumulate at the site

arteries become rigid

increased risk for MI, stroke, aneurysms

Question 24

Marfan syndrome

Answer 24

• FBN-1 mutations affect fibrillin, a component of elastic fibers

elastic fibers important in structure/function of large arteries

defective elastic fibers = dissection of large arteries

Question 25

Lymphatic vessels

Answer 25

thin walled channels that conduct tissue fluid to venous system - thinner than veins

one way

lymphatic capillaries, vessels, and trunks

Question 26

Lymphatic capillaries

Answer 26

very similar to blood capillaries

transport lymph to even larger lymphatic vessels that empty into the thoracic R lymphatic duct

these then empty into the L and R subclavian veins

Question 27

Lymphatic vessels

Answer 27

very similar to veins but with thinner walls, also have valves