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A&P 3.1 > Capillaries and Veins > Flashcards

Capillaries and Veins Flashcards

1
Q

How big are capillaries?

A

Microscopic

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2
Q

What do capillaries connect?

A

Arterioles to venules, endothelium, and basement membrane

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3
Q

Where aren’t there capillaries?

A

cornea, lens, epidermis, cartilage

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4
Q

Where are there few capillaries?

A

Tendons and ligaments

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5
Q

Where are there lots of capillaries?

A

brain/nervous tissue; endocrines system; kidneys

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6
Q

What are the three kinds of capillaries?

A

Continuous capillaries
Fenestrated capillaries
Sinusoid capillaires

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7
Q

Where are continuous capillaries found?

A

Found in most tissue, eg skeletal muscle

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8
Q

Describe the basement membrane of a continuous capillary. How are the endothelial cells held together?

A

Basement membrane forms a continuous ring around capillary

Endothelial cells are held together by tight junctions

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9
Q

What special structure is found in the endothelial cells of continuous capillaries?

A

intercellular clefts

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10
Q

How big is the intercellular cleft in a continuous capillary? What can pass through it? Where aren’t they?

A

~4 nm wide
Glucose and other small solutes can get through the clefts
The capillaries in the brain do not have these clefts- because of blood brain barrier

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11
Q

What is a fenestrated capillary and why is it named as such?

A

These endothelial cells have filtration pores (windows),

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12
Q

How big are the windows in a fenestrated capillary, and what covers them?

A

~20-100 nm, often spanned by a glycoprotein membrane

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13
Q

Where are fenestrated capillaries found?

A

Found in kidneys, endocrine glands, small intestine

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14
Q

Describe the basement membrane of a fenestrated capillary

A

surrounds the fenestrated capillaries

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15
Q

Where are sinusoid capillaries found?

A

Found in liver, bone marrow, spleen

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16
Q

What does a sinusoid capillary look like?

A

There are spaces in between the endothelial cells

Basement membrane in incomplete or absent

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17
Q

Why do sinusoid capillaries have space between the endothelial cells?

A

These spaces allow things like albumin, clotting factors, etc to get into the blood (from the liver/marrow/spleen where they are produced)

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18
Q

What are the three specialized structures in the capillary bed?

A

Metarteriole
Thoroughfare channel
Precapillary sphincter

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19
Q

Where is the metarteriole?

A

Short, 1st section of the thoroughfare channel to venule, when an arteriole gives off a branch to a capillary bed area

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20
Q

What surrounds the met metarteriole?

A

Has isolated smooth muscle fibers around this short section

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21
Q

Where is the thoroughfare channel?

A

Longer section, from metarteriole to venule

Is the continuation of the metarteriole, capillaries come off this part

22
Q

Where does the thoroughfare channel go? What can it act as?

A

Will empty to a venule- Sometimes acts as a shunt, if precapillary sphincters are closed

23
Q

How many capillary beds come off the thoroughfare channel?

A

Usually 10-100 capillary beds are supplied off this channel

24
Q

What is the pre capillary sphincter?

A

Smooth muscle wrapped around the beginning of a capillary bed

25
Q

What does the pre capillary sphincter do?

A

Autoregulation: if theres plenty to O2, will slow blood flow for a short time

26
Q

__of the body’s capillaries are shut down at any given time, because there’s not enough ______ to fill everything.

A

¾

Blood

27
Q

Several _____ unite to form a venule

A

capillaries

28
Q

Will a vein ever be as thick as an artery?

A

No

29
Q

How many layers does a vein have? Which is the thickest?

A

3

Tunica adventitia

30
Q

How to veins prevent back flow? Where are these structures located?

A

Have valves to prevent the backflow of blood, only on tunica intima

31
Q

What two “pumps” allow for veinous return?

A

Skeletal Pump

Respiratory Pump

32
Q

What is the skeletal pump?

A

In the legs when the skeletal muscle contracts, blood is pushed up towards the heart

33
Q

What is the respiratory pump?

A

During respiration, the diaphragm flattens and moves downwards, this decreases pressure in the thoracic cavity, increases pressure in abdominal cavity, and blood will flow to an area of lower pressure- returning to the thoracic cavity

34
Q

What is hemostasis?

A

Cessation of bleeding

35
Q

What is a thrombus?

A

A blood clot that develops in the luminal wall of a blood vessel

36
Q

What is a thrombosis?

A

Clotting in an unbroken blood vessel

37
Q

What is hemophilia?

A

A genetic disorder, clotting is diminished or absent

38
Q

What is an embolus?

A

“A mass” A substance that is carried in the blood and obstructs a blood vessel
eg an air bubble, a blood clot, a fat globule

39
Q

What is an aneurysm?

A

A sac formed by the dilation of a wall of an artery or vein

40
Q

What are the “layers” of blood flow called?

A

Laminar flow

41
Q

Describe laminar flow

A

Blood in the middle of an artery flows faster than blood near the walls, due to friction
The diameter of a vessel has a powerful influence on blood flow velocity

42
Q

In addition to laminar flow, what also impacts blood flow?

A

Viscosity and peripheral pressure

43
Q

What does MAP stand for?

A

Mean arterial pressure

44
Q

What is MAP?

A

Pressure that propels blood to tissues
A measure of stress on blood vessels
Since diastole lasts longer than systole, it’s not just an average of the two

45
Q

How is MAP determined?

A 
MAP = Diastolic pressure + ⅓( Pulse Pressure)	Pulse pressure: Systolic-Diastolic
MAP = Diastolic pressure + ⅓(Systolic-Diastolic)
46
Q

What is hypertension?

A

Abnormally high BP

Chronic resting BP higher than 140/90 mmHg

47
Q

What is atherosclerosis?

A

Tearing of endothelium due to pressure, causes lesions that lead to lipid deposits along the walls of vessels

48
Q

What is hypotension?

A

Chronic systolic pressure below 100mmHg

49
Q

What is net filtration/reabsorption pressure?

A

The difference between fluids entering/exiting capillaries

50
Q

What is hydrostatic pressure?

A

Fluid filters out of the arterial end of a capillary

The physical force exerted by blood against the capillary wall

51
Q

What is colloidal osmotic pressure?

A

Fluid osmotically reenters at the venous end of capillary

Albumins primarily responsible for re entry of fluid back into capillary

52
Q

How, where, and in what percents is fluid reabsorbed?

A

Capillaries reabsorb 85% of fluid they filter, remaining 15% absorbed/returned by lymphatic system

A&P 3.1 (20 decks)

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