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biol 1190 > Chapter 21: Blood vessels > Flashcards

Chapter 21: Blood vessels Flashcards

1
Q

How many layers to blood vessels have with the exception of capillaries

A

3 layers:
1. tunica interna (innermost)
2. Tunica media ((middle)
3. tunica externa

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2
Q

What layer of blood vessels helps to constrict them

A

Tunica media: the smooth muscle

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3
Q

Endothelium for blood vessels is

A

one layer; gas exchange is easier

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4
Q

are arteries or veins thicker

A

arteries are thicker because they have more smooth muscle

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5
Q

The walls of arteries are elastic which allow…

A

them to absorb pressure created by the ventricles of the heart as they pump blood into the arteries eg. aorta

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6
Q

What are the different types of arteries

A
  • elastic arteries
  • muscular arteries
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7
Q

Elastic arteries (conducting arteries)

A
  • large diameter
  • more elastic fibers, less smooth muscle
  • function as pressure reservoirs
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8
Q

Example of elastic artery

A

aorta: a lot more elastic fibers and less smooth muscle

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9
Q

Muscular arteries ( distributing arteries)

A
  • medium diameter
  • more smooth muscle, fewer elastic fibers
  • distribute to various parts of the body
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10
Q

As arteries branch they become …

A

muscular arteries

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11
Q

Anastomoses

A

the union of the branches of two or more arteries supplying the same region of the body

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12
Q

Anastomosis results in

A

collateral circulation
- provides an alternate route for blood flow
- example: circle of willis

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13
Q

Arteries that do not form anastomosis is called

A

end arteries
- if an end artery is blocked, blood cannot get to that particular region of the body and necrosis occurs

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14
Q

Capillaries

A
  • are microscopic vessels that usually connect arterioles and venules
  • composed of a single layer of cells and basement membrane
  • because their walls are so thin, they allow gas exchange
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15
Q

capillary networks are found near

A

almost every cell in the body

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16
Q

Continuous capillaries

A

individual cells join to one another
- not much space between cells

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17
Q

What is the intercellular cleft

A

space which allows wbcs to squeeze through to emigrate

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18
Q

Fenestrated capillaries

A
  • they have pores
  • allow arteries to exchange substances
  • present in the kidneys
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19
Q

Sinusoid capillaries

A
  • has incomplete basement membrane
  • allows for greater exchange
  • has bigger holes than fenestrated capillaries and allows red blood cells to squeeze through
  • wbcs can freely enter
  • present in the liver
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20
Q

Venules

A

are small vessels that are formed by the union of several capillaries
- drain blood from capillaries into veins

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21
Q

Veins

A
  • formed by the union of several venules
  • less elastic tissue and smooth muscle than arteries
  • have thicker tunica externa and thinner tunica interna and media
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22
Q

Varicose veins

A

are formed when venous valves become weak of damaged
- cannot prevent backwards flow and veins will buldge
- dilated and twisted in appearance

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23
Q

Spider veins

A

are dilated venules close to the skin, especially in the lower limb and face
- spider veins appear red, blue or purple, resembling a spider web

24
Q

At rest, the largest portion of the blood is in systemic..

A

veins and venules, which are considered blood reservoirs

25
Q

Substances cross capillary walls by …

A
  • diffusion
  • transcystosis
  • bulk flow
26
Q

Diffusion in capillaries

A

substances move from an area of high concentration to an area of low concentration
- substances in blood or interstitial fluids can cross the capillary walls by: intercellular clefts, fenestrations and diffusion through the plasma membrane of the endothelial cells

27
Q

Transcytosis in capillaries

A

combination of endo and exocytosis
- example: insulin

28
Q

Bulk flow in capillaries

A

movement of liquid plasma and small particles
- everything goes in the same direction unlike diffusion

29
Q

Bulk flow occurs from an area of

A

higher pressure to an area of lower pressure and it continues as long as there is a pressure difference between two areas

30
Q

What is bulk flow important for

A

important for regulation of the relative volumes of blood and interstitial fluid
- in contrast diffusion is the regulation of movement of solutes

31
Q

Bulk flow is calculated by

A

filtration and absorption

32
Q

Filtration in bulk flow

A

the pressure-driven movement of fluid and solutes from blood capillaries into interstitial fluid

33
Q

What promotes filtration

A

blood hydrostatic pressure (BHP) and intersitital fluid osmotic pressure (IFOP) promote filtration

34
Q

Reabsorption in bulk flow

A

the pressure-driven movement of fluid and solutes from interstitial fluid into blood capillaries

35
Q

What promotes reabsorption

A

interstitial fluid hydrostatic pressure (IFHP) and blood colloid osmotic pressure (BCOP) promote reabsorption

36
Q

Net filtration pressure

A

NFP = (BHP + IFOP) - (BCOP + IFHP)

37
Q

Blood flow

A

the volume of blood that flows through any tissue in a given time period (in mL/min)

38
Q

Total blood flow is represented by…

A

cardiac output

39
Q

Cardiac output equals

A
  • heart rate X stroke volume (mL of blood pushed out by ventricles in each contraction)
  • mean arterial pressure (MAP) divided by resistance
40
Q

Vascular resistance

A

is the opposition to blood flow due to friction between blood and the walls of blood vessels
- the higher the resistance the lower the blood flow

41
Q

Vascular resistance depends on 3 factors…

A
  1. the size of the blood vessel lumen
    - arteries and veins have larger diameters and lower resistance
    - arterioles, venules and capillaries contribute to the most resistance
  2. blood viscosity
  3. total blood vessel length
42
Q

What is a major function of arterioles

A

to control systemic vascular resistance through vasodilation or vasoconstriction

43
Q

Velocity of blood flow

A

is inversely related to the total cross-sectional area of blood vessels

(blood flow is the volume of blood that flows through a tissue in a given period of time)

44
Q

Venous return

A

is the volume of blood flowing back to the heart through the systemic veins.
- it occurs due to the pressure generated by contractions of the heart’s left ventricle

45
Q

What 3 factors affect venous return

A
  1. contraction and relaxation of the heart
  2. skeletal muscle pump
  3. respiratory pump
46
Q

How does contraction and relaxation affect venous return

A

relaxation causes return at diastole; the volume is higher and the pressure is lower which helps blood return from the vena cava to the right atrium. The pressure difference causes it

47
Q

What controls blood pressure and blood flow

A

Medulla oblongata contains the cardiovascular center which is a group of neurons that regulates the heart rate, contractility and blood vessel diameter

48
Q

Homeostasis - negative feedback loop for decreased blood pressure explained

A
  1. stimulus: decreased blood pressure
  2. controlled condition: blood pressure
  3. receptors: baroreceptors in the carotid sinus and aortic arch
  4. input: stretch less and decrease the rate of nerve impulses
  5. control centers: cardiovascular center
  6. Output: increased sympathetic and decreased parasympathetic responses.
  7. Effectors: heart and blood vessels which increase stroke volume, hr and vasoconstriction
  8. Response: blood pressure is increased and returns to homeostasis
49
Q

ANP (atrial natriuretic peptide) is made during

A

high blood pressure to decrease it

50
Q

What is shock

A

shock is failure of a cardiovascular system to deliver enough oxygen and nutrients to meet the metabolic demands for delivery of oxygen and nutrients and removal of wastes

51
Q

what are the four different types of shock

A
  1. hypovolemic
  2. cardiogenic
  3. vascular (distributive)
  4. obstructive
52
Q

Homeostatic responses to shock

A
  • activation of renin-angiotensin-aldosterone system (constricts blood vessels, increases resistance and blood pressure)
  • secretion of ADH
  • release of local vasodilators
53
Q

signs and symptoms of shock

A
  • low systolic bp
  • tachycardia (due to sympathetic stimulation from release of epinephrine and norepinephrine)
  • weak pulse (reduced cardiac output)
  • skin is cool and clammy (vasoconstriction to nonvital organs)
  • mental state is altered
  • urine formation reduced (dark and concentrated urine)
  • thirst
  • pH is low due to acidosis (build up of lactic acid) –> not enough O2 going to cells of the body
  • nausea; vasoconstriction of blood vessels of the digestive system
54
Q

What is the source of the hepatic portal system

A

venous system returns blood from the digestive tract and spleen into the liver where raw nutrients are processed before they return to the heart

55
Q

Age related changes to the CV system

A
  • loss of compliance (elasticity) of aorta
  • reduction in cardiac muscle fiber size
  • decline in maximal heart rate
  • increased systolic bp

biol 1190 (16 decks)

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