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Anatomy And Physiology 2 > Chapter 19: Blood Vessels > Flashcards

Chapter 19: Blood Vessels Flashcards

0
Q

Capillaries :

A

Contact tissue cells; directly serve cellular needs

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1
Q

Arteries do what?

A

Carry blood away from the heart; oxygenated except for pulmonary circulation and umbilical vessels of fetus

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2
Q

Veins:

A

Carry blood toward heart

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3
Q

Lumen :

A

Central blood containing space

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4
Q

Capillaries have which type of tissue?

A

Endothelium with sparse basal lamina

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5
Q

Where is the subendothelial layer found?

A

In vessels larger than 1 mm ; connective tissue basement membrane

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6
Q

Tunica media:

A

Smooth muscle and sheets of elastin

  • sympathetic vasomotor nerve fibers control vasoconstriction and vasodilation of vessels
  • influence blood flow and blood pressure
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7
Q

Tunica externa (tunica adventitia):

A

Collagen fibers protect and reinforce ; anchor to surrounding structures

  • contains nerve fibers, lymphatic vessels
  • vaso vasorum of larger vessels nourishes external layer
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8
Q

Elastic arteries:

A

▪️large thick walled arteries with elastin in all three tunics
▪️aorta and it’s major branches
▪️large lumen offers low resistance
▪️inactive in vasoconstriction
▪️act as pressure reservoirs– expand and recoil as blood ejected from heart
-smooth pressure downstream

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9
Q

Muscular arteries:

A

▪️distal to elastic arteries. Deliver blood to body organs
▪️thick tunica media with more smooth muscle
▪️active in vasoconstriction

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10
Q

Arterioles:

A

▪️smallest arteries
▪️lead to capillary beds
▪️control flow into capillary beds via vasodilation and vasoconstriction.

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11
Q

Capillaries:

A

▪️microscopic blood vessels
▪️walls of thin tunica intima. One cell thick
▪️pericytes : helps stabilize their walls and control permeability
▪️diameter allows only single RBC to pass at a time

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12
Q

Capillaries are in all tissues EXCEPT?

A

Cartilage
Epithelia
Cornea and lens of eye

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13
Q

What is the function of capillaries?

A

Exchange of gases, nutrients, wastes, hormones between blood and interstitial fluid

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14
Q

What are the 3 structural types of capillaries ?

A

Continuous capillaries
Fenstrated capillaries
Sinusoid capillaries

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15
Q

Continuous capillaries:

A

▪️abundant in skin and muscles :
-tight junctions connect endothelial cells
- intercellular clefts allow passage of fluids and small solutes
▪️continuous capillaries of brain are unique :
- tight junctions complete, forming blood brain barrier

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16
Q

Fenstrated capillaries:

A

▪️some endothelial cells contain pores (fenstrations )
▪️more permeable than continuous capillaries
▪️function in absorption or filtrate formation (small intestines, endocrine glands, kidneys)

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17
Q

Sinusoid capillaries:

A

▪️fewer tight junctions; usually Fenstrated ; larger intercellular clefts; large lumens
▪️blood flow sluggish– allows modification.
- large molecules and blood cells pass between blood and surrounding tissues
▪️FOUND ONLY IN LIVER, BONE MARROW, SPLEEN, ADRENAL MEDULLA
▪️macrophages in lining to destroy bacteria

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18
Q

What is microcirculation in capillary beds?

A

▪️interwoven network of capillaries between Arterioles and venules
▪️terminal Arteriole ➡️ metarteriole

▪️metarteriole continuous with thoroughfare channel
▪️thoroughfare channel ➡️post capillary venule that drains bed

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19
Q

Vascular shunt:

A

Metarteriole–thoroughfare channel

-directly connects terminal Arteriole and post capillary venule

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20
Q

True capillary:

A
  • 10 to 100 exchange vessels per capillary bed

- branch off metarteriole or terminal Arteriole

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21
Q

How is the blood flow through capillaries?

A

▪️true capillaries normally branch from metarteriole and return to thoroughfare channel
▪️pew capillary sphincters regulate blood flow into true capillaries.
Blood may go into true capillaries or to shunt
▪️regulated by local chemical conditions and vasomotor nerves

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22
Q

Venous system- venules:

A

▪️formed when capillary beds unite.
-smallest post capillary venules
-very porous ; allow fluids and WBC into tissues
-consists of endothelium and a few pericytes
▪️larger venules have one or two layers of smooth muscle cells

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23
Q

Veins:

A

▪️formed when venules converge
▪️have thinner walls, larger lumens compared with corresponding arteries
▪️blood pressure lower than in arteries
▪️thin tunica media; thick tunica externa of collagen fibers and elastic networks
▪️called capacitance vessels (blood reservoirs ) ; contain up to 65% of blood supply

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24
Q

Vein adaptions ensure return of blood to heart despite low pressure:

A

▪️large - diameter lumens offer little resistance
▪️venous valves prevent backflow of blood. Most abundant in veins of limbs
▪️venous sinuses : flattened veins with extremely thin walls (coronary sinus of heart)

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25
Q

Vascular anastomoses :

A

▪️interconnections of blood vessels
▪️arterial anastomoses provide alternate pathways (collateral channels) to given body region.
- common at joints, in abdominal organs , brain, and heart NONE IN retina, kidneys , spleen
▪️Vascular shunts f capillaries are examples of arteriovenous anastomoses
▪️venous anastomoses are common

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26
Q

Blood flow:

A

▪️volume of blood flowing through vessel, organ, or entire circulation in given period.

  • measured as ml/min
  • equivalent to cardiac output for entire vascular system
  • relatively constant when at rest
  • varies widely through individual organs based on needs
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27
Q

Resistance(peripheral):

A

▪️opposition to flow

▪️measure of amount of friction blood encounters with vessel walls, generally in peripheral (systemic) circulation

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28
Q

What are the three important sources of resistance?

A

Blood viscosity
Total blood vessel length
Blood vessel diameter

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29
Q

Factors that remain constant in resistance?

A

▪️blood viscosity : the stickiness of blood due to formed elements and plasma proteins.
-increased viscosity = increased resistance
▪️blood vessel length : longer vessel = greater resistance encountered

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30
Q

Does blood vessel diameter have a great influence on resistance?

A

Yes

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31
Q

What are major determinants of peripheral resistance?

A

Small diameter Arterioles

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32
Q

Do abrupt changes in diameter or fatty plaques from atherosclerosis dramatically increase resistance ?

A

Yes.

  • disrupt laminar flow and cause turbulent flow.
    • irregular fluid motion ➡️ increased resistance
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33
Q

Relationship better bold flow, blood pressure, and resistance ?

A
  • if pressure increases = blood flow increase

- if R increase = blood flow decrease

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34
Q

Where is systemic blood pressure the highest?

A

In aorta

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35
Q

Systemic pressure declines throughout pathway. True or false.

A

True

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36
Q

In systemic pressure what is the pressure in the right atrium?

A

0mm Hg

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37
Q

Where is the steepest drop of systemic pressure occur?

A

Arterioles

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38
Q

Arterial blood pressure reflects what two factors?

A

Elasticity
And
Volume of blood forced into them at any time

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39
Q

What is the blood pressure near the heart called ?

A

Pulsatile

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40
Q

Systolic pressure:

A

Pressure exerted in aorta during ventricular contraction. Ex 120mm Hg

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41
Q

Diastolic pressure:

A

Lowest level of aortic pressure. Ex: 80mm Hg

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42
Q

Pulse pressure:

A

Is the difference between systolic and diastolic pressure (throbbing of arteries)

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43
Q

Mean arterial pressure:

A

Pressure that propels blood into tissues

- MAP = diastolic pressure + 1/3 pulse pressure

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44
Q

Pulse pressure and MAP both decline with increasing distance from heart. True or false ?

A

True

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45
Q

Where does the capillaries blood pressure range?

A

17 to 35 mm Hg

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46
Q

Venous blood pressure:

A

Small pressure gradient : 15 mm Hg

-low reassure due to cumulative effects of peripheral resistance

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47
Q

What are the 3 factors that aid in venous return?

A

Muscular pump
Respiratory pump
Venoconstriction

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48
Q

Muscular pump:

A

Contraction of skeletal muscles “milks” blood toward heart; valves prevent backflow

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49
Q

Respiratory pump:

A

Pressure changes during breathing move blood toward heart by squeezing abdominal veins as thoracic veins expand

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50
Q

Venoconstriction:

A

Under sympathetic control pushes blood toward heart

51
Q

Maintaining blood pressure requires:

A

Cooperation of heart, blood vessels, and kidneys

52
Q

Main factors influencing blood pressure:

A
  • cardiac output
  • peripheral resistance
  • blood volume
53
Q

Cardiac output is determined by what?

A

Venous return , neural and hormonal controls

54
Q

Resting heart rate maintained by what?

A

Cardioinhibitory center via parasympathetic vagus nerves

55
Q

Stroke volume is controlled by what?

A

Venous return

56
Q

During stress, cardioacceleratory center increases heart rate and stroke volume via sympathetic stimulation. True or false

A

True.

-ESV decreases and MAP increases

57
Q

He does short term neural and hormonal control blood pressure?

A

Counteract fluctuations in blood pressure by altering peripheral resistance and CO

58
Q

Long term renal regulation intros of blood pressure:

A

Counteracts fluctuations in blood pressure by altering blood volume

59
Q

Neural controls of peripheral resistance:

A

Maintain MAP by altering blood vessel diameter

-if low blood volume all vessels constricted except those in heart and brain

60
Q

How do short term neural mechanisms control blood pressure?

A

Operate via reflex arcs that involve :
▪️baroreceptors
▪️cardiovascular center of medulla
▪️vasomotor fibers to heart and vascular smooth muscle
▪️sometimes input from chemoreceptors and higher brain centers

61
Q

Cardiovascular center:

A

▪️clusters of sympathetic neurons on medulla oversee changes in CO and blood vessel diameter
▪️consists of cardiac centers and vasomotor center
▪️vasomotor center sends steady impulses via sympathetic efferent story blood vessels ➡️ moderate constriction called vasomotor tone
▪️receives inputs from baroreceptors, chemoreceptors, and higher brain centers

62
Q

Where are baroreceptors located?

A

Carotid sinuses
Arortic arch
Walls of large arteries in neck and thorax

63
Q

Increased blood pressure stimulates baroreceptors to do what?

A

To increase input to vasomotor center.

  • inhibits vasomotor and cardioacceleratory center causing arteriolar dilation and venodilation
  • stimulates cardioinhibitory center
  • decreased blood pressure
64
Q

Short term mechanism: baroreceptors decrease in blood pressure due to ?

A
  • Ateriolar vasodilation
  • venodilation
  • decreased cardiac output
65
Q

Short term: chemoreceptors :

A

▪️chemoreceptors in aortic arch and large arteries of neck detect increase in CO2 or drop in pH or O2
▪️caused by increased blood pressure by:
-signaling cardioacceleratory center ➡️ increase CO
-signaling vasomotor center ➡️ increase vasoconstriction

66
Q

Short term mechanism: influence of higher brain centers :

A

▪️reflexes in medulla
▪️hypothalamus and cerebral cortex can modify arterial pressure via relays to medulla
▪️hypothalamus increases blood pressure during stress
▪️hypothalamus mediates redistribution of blood flow during exercise and changes in body temperature

67
Q

Short term mechanisms : hormonal controls:

A
  • Short term regulation via changes in peripheral resistance
  • long term regulation via changes in blood volume
68
Q

Short term mechanisms : hormonal control increased blood pressure ?

A
  • Epinephrine and norepinephrine from adrenal gland ➡️ increased CO and vasoconstriction
  • angiotensin II stimulates vasoconstriction
  • high ADH levels cause vasoconstriction
69
Q

Short term mechanism : hormonal controls LOW blood pressure?

A

Atrial natriuretic peptide caused decreased blood volume by antagonizing aldosterone

70
Q

Long term mechanism: renal regulation?

A

▪️baroreceptors quickly adapt to chronic high or low BP so are ineffective
▪️long term mechanisms control BP by altering blood volume via kidneys
▪️kidneys regulate arterial blood pressure:
1.direct renal mechanism
2.indirect real mechanism

71
Q

What two mechanisms do kidneys use to regulate arterial blood pressure ?

A

Direct renal

And indirect renal (renin-angiotensin-aldosterone)

72
Q

Direct renal mechanism:

A

Alters bold volume independently of hormones.

  • increase BP or blood volume causes elimination of more urine this reducing BP
  • Decreased BP Or blood volume causes kidneys to conserve water, BP rises
73
Q

Renin-angiotensin-aldosterone mechanism:

A
  • Decrease ⬇️ arterial pressure = release of renin
  • renin catalyzes conversion of angiotensin from liver to angiotensin I
  • angiotensin converting enzyme especially from lungs converts to angiotensin I to angiotensin II
74
Q

Functions of Angiotensin II?

A 
▪️increase blood volume:
 -stimulates aldosterone secretion 
 - causes ADH release 
 - triggers hypothalamic thirst center 
▪️causes vasoconstriction directly increasing blood pressure
75
Q

Systolic pressure is heard first when using a korotkoff and stethoscope?

A

Pressure when sounds first occur as blood starts to spurt through artery

76
Q

Diastolic pressure heard when while using karotkoff and stethoscope?

A

Is pressure when sounds disappear because artery is no loner constricted , blood is flowing freely

77
Q

Hypertension is classified by BP of what?

A

140/90 or higher

78
Q

Prolonged hypertension may cause what?

A

Heart failure
Vascular disease
Renal failure
Stroke

79
Q

Primary/essential hypertension:

A

▪️90% of hypertensive conditions
▪️no underlying caused identified
▪️no cure but can be controlled

80
Q

Secondary hypertension:

A

-Due to identifiable disorders including obstructed renal arteries , kidney disease , and endocrine disorders such as hyperthyroidism and cushions syndrome

81
Q

Hypotension:

A

Low blood pressure usually 90/60 mm Hg

82
Q

Orthostatic hypotension :

A

Temporary low BP an dizziness when suddenly rising from sitting or reclining position

83
Q

Chronic hypotension:

A

Hint of poor nutrition and warning sign for Addison’s disease or hypothyroidism

84
Q

Acute hypotension:

A

Important sign of circulatory shock ; threat for surgical patients and those in ICU

85
Q

Tissue perfusion involved in:

A

▪️delivery of O2 and nutrients to and removal of wastes from tissue cells
▪️gas exchange (lungs)
▪️absorption of nutrients (digestive tract)
▪️urine formation
▪️rate of flow is precisely right amount to provide proper function

86
Q

Velocity in blood flow is fastest where?

A

In aorta

87
Q

Velocity of blood flow is slowest where?

A

In capillaries

88
Q

What is auto regulation?

A

▪️automatic adjustment of blood flow to each tissue
▪️controlled intrinsically by modifying diameter of local Arterioles feeding capillaries
- independent of MAP which is controlled as needed to maintain constant pressure
▪️organs regulate own blood flow by caring resistance of own Arterioles

89
Q

Two types of auto regulation?

A

Metabolic control
And
Myogenic control

90
Q

Metabolic autoregulation control:

A

Vasodilation of Arterioles and relaxation of precapillary sphincters occur in response to
-declining tissue O2
-substances from metabolically active tissues (H+ , K + , adenosine , prostaglandins )
And inflammatory chemicals

91
Q

Effects of metabolic autoregulation?

A

▪️effects : relaxation of vascular smooth muscle and release of NO (powerful vasodilator ) by endothelial cells
▪️endothelins: released from endothelium are potent vasoconstrictors
▪️NO and endothelins balanced unless blood flow inadequate , then NO wins
▪️inflammatory chemicals also cause vasodilation

92
Q

Myogenic autoregulation controls:

A

▪️myogenic responses keep tissue perfusion constant despite most fluctuations in systemic pressure
▪️vascular smooth muscle responds to stretch :
-passive stretch (increase intravascular pressure) promotes tone and vasoconstriction
-reduced stretch promotes vasodilation and increases blood flow to the tissue

93
Q

Angiogenesis :

A

Number of vessels to region increases and existing vessel enlarge
-common in heart when coronary easel occluded, or throughout body in people in high altitude areas

94
Q

Blood flow: skeletal muscles :

A
  • at ret myogenic and general neural mechanisms predominate - maintain ~ 1 L /min
  • during muscle activity : local controls override sympathetic vasoconstriction
95
Q

What is the constant blood flow to the brain?

A

Averages 750 ml/min

96
Q

Brain blood flow: metabolic control:

A

Decreased pH of increased carbon dioxide caused marked vasodilation

97
Q

Blood flow to brain: myogenic control:

A
  • decreased MAP causes cerebral vessels to dilate

- increased MAP. Causes cerebral vessels to constrict

98
Q

Brain MAP below 60 mm Hg causes?

A

Syncope (fainting )

99
Q

Brian MAP above 160 causes?

A

Cerebral edema

100
Q

Blood flow through the skin:

A
  • Supplies nutrients to cells (autoregulation in response to O2 needs)
  • helps regulate body temperature (neurally controlled ) - primary function
  • provides a blood reservoir (neurally controlled )
101
Q

Blood flow to venous plexus we below skin surfaces regulate body temperature :

A
  • Varies from 50 ml/min to 2500 ml/min , depending on body temp.
  • controlled by sympathetic nervous system reflexes initiated by temperature receptors and central nervous system
102
Q

Temperature regulation:

A
  • Hypothalamic signals reduce vasomotor stimulation of skin vessels➡️
  • warm blood flushes into capillary beds ➡️
  • heat radiates from skin
103
Q

Sweat causes vasodilation via_?

A

Bradykinin in perspiration

- bradykinin stimulates NO release

104
Q

As temperature decreases, blood is shunted into deeper more vital organs. True or false

A

True

105
Q

Pulmonary circuit unusual:

A
  • Pathway short
  • arteries/Arterioles more like veins /venules (thin walled large lumen)
  • arterial resistance and pressure are low (24/10 mm Hg)
106
Q

The auto regutory mechanism is opposite in most tissues (lungs) :

A

Low O2 levels cause vasoconstriction ; high levels promote vasodilation
- allows blood flow to O2 rich areas of lungs

107
Q

Blood flow: heart: during ventricular systole ??

A

Coronary vessels are compressed

  • myocardial blood flow ceases
  • stored myoglobin supplies sufficient oxygen
108
Q

Blood flow : heart: during diastolic high aortic pressure forces blood through coronary circulation. True or false?

A

True

109
Q

Blood flow: heart: at rest blood flow equals?

A

~ 250 ml/min ; control probably myogenic

110
Q

During strenuous exercise, heart blood flow does what?

A
  • Coronary vessels dilate in response to local acclimation of vasodilators
  • blood flow may increase 3 or 4 times
    - important — cardiac cells use 65% of O 2 delivered so increased blood flow provides more O 2
111
Q

Vaso motion (in capillaries):

A

Slow, intermittent flow

-reflects on/off opening and closing of precapillary sphincters

112
Q

Capillary exchange of respiratory gases and nutrients :

A

▪️diffusion down concentration gradients.
O2 and nutrients from blood to tissues.
CO2 and metabolic waste from tissues to blood
▪️lipid soluble molecules diffuse directly through endothelial membranes
▪️water soluble solutes pass through clefts and fenstrations
▪️larger molecules such as proteins are actively transported in pinocytotic vesicles or caveolae

113
Q

Fluid leaves capillaries at arterial end; most returns to blood at venous end . True or false?

A

True.

Extremely important in determining relative fluid volumes in blood and interstitial space

114
Q

Capillary hydrostatic pressure:

A

Tend a to force fluids trough capillary walls

- greater at arterial end (35 mm Hg) of bed than at venule end (17mm Hg)

115
Q

Interstitial fluid hydrostatic pressure:

A
  • Pressure that would push fluid into vessel

- usually assumed to be zero because of lymphatic vessels

116
Q

Capillary colloid pressure (oncotic) :

A

-Created by mom diffusable plasma proteins, which draw water tears themselves
~ 26 mm Hg
-interstitial fluid osmotic pressure
(Low ~ 1mm Hg due to low protein content )

117
Q

Hypovolemic shock:

A

Results from large scale blood loss

118
Q

Vascular shock:

A

Results from extreme vasodilation and decreased peripheral resistance

119
Q

Cardiogenic shock:

A

Results when an inefficient heart cannot sustain adequate circulation.

120
Q

Twhat are the two main circulations?

A

Pulmonary

Systemic

121
Q

Pulmonary circulation :

A

Short loop that runs from heart to lungs and back to heart

122
Q

Systemic circulation :

A

Long loop to all parts of body and back to heart

123
Q

The heart pumps blood by what week of development ?

A

4 th week

124
Q

What determines whether the vessel becomes an artery or vein?

A

Vascular endothelial growth factor

125
Q

What forms rudimentary vascular tubes ?

A

Blood islands guided by cues

126
Q

Where does endothelial lining rise from?

A

Mesodermal cells in blood vessels

Anatomy And Physiology 2 (7 decks)

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