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BIO 224 > Ch. 18 Blood vessels > Flashcards

Ch. 18 Blood vessels Flashcards

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1
Q

What are the 3 main type of blood vessels?

A

Arteries - blood away from heart - oxygenated
Capillaries - direct contact with tissue cells
Veins - Carry blood to heart - deoxygenated

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2
Q

What makes up a capillary wall?

A

Endothelium with sparse basal lamina

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3
Q

What is the tunica intima made of?

A

Endothelium- simple squamous, continuous with endothelium

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4
Q

What are the characteristics of tunica intima?

A
  • Can secrete chemicals that can dilate or constrict
  • Repels blood
  • leukocytes can adhere if inflamed
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5
Q

What is the tunica media made of?

A

Smooth muscle, collagen and sheets of elastin

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6
Q

What are the characteristics of the tunica media?

A

Responsible for maintaining BP and BF by dilation or constriction

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7
Q

What nerve innervates the tunica media?

A

Sympathetic vasomotor nerve

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8
Q

What is tunica adventitia made of?

A

Loose connective tissue

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9
Q

What are the functions of the tunica adventitia?

A

Anchors blood vessel and provides passage for small nerves and lymphatic vessels

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10
Q

Arteries are divided into 3 groups based on what?
What are 3 groups?

A

Size and function

Elastic, Muscular, Arterioles

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11
Q

Elastic arteries are also called

A

Conducting arteries because they conduct blood from heart to medium sized vessels

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12
Q

What are the characteristics of elastic arteries?

A
  • Thick-walled with large, low resistance lumin
  • Contain substantial smooth muscle but don’t vasoconstrict
  • Act as pressure reservoirs that expand and recoil as blood is ejected - allows for continuous flow & lessens fluctuations in blood flow
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13
Q

What are some common elastic arteries?

A

Aorta, common carotid, subclavian, pulmonary trunk

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14
Q

What are muscular arteries also called?

A

Distributing arteries - deliver blood to body organs

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15
Q

What are the characteristics of muscular arteries?

A
  • account for most of the names arteries
  • Thickest tunica media - more smooth muscle, less elastic
  • Acitve in vasoconstriction
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16
Q

What are some common muscular arteries?

A

Brachial, femoral, renal, splenic arteries

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17
Q

Arterioles are also called

A

Resistance arteries bc of changing diameters

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18
Q

What are the characteristics of arterioles?

A
  • Larger contain 3 tunics, smaller have smooth muscle and endothelial cells
  • Lead to capillary beds
  • Control amount of blood into capillary beds by vasodilation or constriction
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19
Q

Capillaries are made of

A

endothelium - just a thin tunica intima

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20
Q

What are the functions of capillaries

A

exchange of gases, nutrients, waste, hormones etc between blood and interstitial fluid

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21
Q

Capillaries supply almost every cell except

A

cartilage, epithelia, cornea, and lens of the eye

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22
Q

Pericytes

A

Spider shaped stem cells which help stabilize capillary walls, control permeability and play a role in vessel repair

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23
Q

Capillary endothelial cells are joined by

A

tight junctions with gaps called intercellular clefts

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24
Q

Intercellular clefts allow for

A

passage of fluids and small solutes

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25
Q

What are the 3 types of capillaries?

A

Continous, fenestrated, sinusoidal

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26
Q

Continuous capillaries are found

A

in skin, muscles, lungs, and CNS
BBB in brain

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27
Q

Fenestrated capillaries are found in areas where

A

active filtration (kidneys) or filtration (intestines) or endocrine hormone secretion

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28
Q

Fenestrated capillaries look like —– which allows for—-

A

swiss cheese & increases permeability

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29
Q

Sinusoidal capillaries are found in and contain?

A

Macrophages - found in liver, bone marrow, spleen and adrenal medulla

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30
Q

What is a capillary bed?

A

interwoven network of capillaries between arterioles and venules

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31
Q

What is microcirculaton?

A

Flow of blood through capillary bed

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32
Q

What 2 types of vessels make up the capillary bed?

A

Vascular shunt - connects arteriole directly with venule
True capillaries - vessels involved with exchange

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33
Q

What are precapillary sphincters?

A

Regulate flow of blood into capillaries
10-100 exchanged vessels per bed
Regulated by local chemical conditions and vasomotor nerves

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34
Q

What 2 parts make up a vascular shunt?

A

Metarteriole and thoroughfare channel

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35
Q

Capillaries unite to form

A

postcapillary venules

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36
Q

Venules consist of

A

endothelium and a few pericytes; very porous - allow fluid and WBC into tissues

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37
Q

Veins are also called

A

capacitance vessels (blood reservoirs) bc they contain up to 65% of blood supply

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38
Q

What are the characteristics of veins?

A

all 3 tunics, but thinner walls with larger lumens
Tunica media is thin, tunica external is thick
contain collagen fibers & elastic
low pressure
have valves

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39
Q

What are the 3 types of veins?

A

Large - larger than 10mm
medium - up to 10mm
Postcapillary venules - smallest

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40
Q

What are some common large veins?

A

Venae cavae, pulmonary veins, jugular veins

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41
Q

venous valves prevent

A

backflow of blood, most abundant in lower limbs

42
Q

Venous sinuses are

A

flattened veins with thin walls, composed of only endothelium. Ex. coronary sinus

43
Q

Varicose veins are caused by

A

incompetent (leaky) valves
Heredity and external conditions, standing, obesity, pregnancy, elevated pressure (delivering baby)

44
Q

What are 4 types of anastomoses?

A

Vascular - interconnections of blood vessels
Arterial - alt. pathways to ensure continuous flow in arteries
Ateriovenous - shunts, ex. metarteriole-thoroughfare
Venous - veins

45
Q

How is blood flow (F) defined?

A

Volume of blood flowing through vessel, organ or entire circulation in any given period

measured in ml/min

46
Q

How is blood pressure (^P) defined?

A

force per unit area exerted on wall of blood vessel by blood

expressed in mm Hg

Pressure gradient keeps blood moving to areas of lower pressure

47
Q

How is resistance (R) defined?

A

Opposition to flow

48
Q

What are 3 sources of resistance to blood flow?

A
  1. Blood viscosity
  2. Total blood vessel length
  3. Blood vessel diameter

*if radius increases resistance decreases (if radius is doubled, resistence drops 1/16)

49
Q

Blood flow is directly porportional to …

A

Blood pressure

If pressure increases blood flow speeds up

50
Q

Blood flow is inversely proportional to…

A

resistance

if resistance increases blood flow decreases

51
Q

Steepest drop in pressure occurs in

A

arterioles

52
Q

Arterial blood pressure is determined by what 2 factors?

A

Elasticity of arteries close to heart

Volume of blood forced at any time

53
Q

What does pulsatile mean?

A

Rises and falls with every heart beat

54
Q

What is systolic pressure?

A

Pressure exerted in aorta during ventricular contraction

avg 120 mmHg

55
Q

What is diastolic pressure?

A

Lowest level of aortic pressure when heart is at rest

56
Q

What is pulse pressure?

A

Difference between systolic and diastolic pressure (SP-DP)

57
Q

What is MAP?

A

The pressure that propels blood into tissues

evens out by end of arteriole / pulse and MAP both decline with increasing distance from heart

58
Q

How do we calculate MAP?

A
59
Q

What are vital signs?

A

Pulse and BP

respiratory rate and temp

60
Q

Capillary bp ranges from

A

35 mm Hg at beginning of bed to 17 mm Hg at end

61
Q

Why is lower capillary pressure more desirable?

A

Could rupture capillaries if too high

Most capillaries are very permeable so low-pressure forces filtrate into interstitial spaces

62
Q

Venous blood pressure is about what mm Hg?

A

15 mm Hg

63
Q

Energy of BP is lost as —– during each circuit

A

heat

64
Q

What are 3 factors that aid in venous return?

A
  1. Muscular pump - skeletal muscles; valves prevent backflow
  2. Respiratory pump - pressure changes during breathing move blood back to the heart
  3. Sympathetic venoconstriction - smooth muscles constrict, pushing blood back to heart
65
Q

What 3 main factors regulate blood pressure?

A
  • Cardiac output
  • Peripheral resistance
  • Blood volume

^P = CO X R

66
Q

Maintaining blood pressure requires the cooperation of..

A

heart, blood vessels and kidneys

67
Q

Anything that increases SV, HR or R will also increase…

A

MAP

68
Q

SV can be affected by

HR is maintained by

R is affected mostly by

A

SV - venous return

HR - medulla oblongata

R - vessel diameter

69
Q

What are the short term regulation of blood pressure: neural controls?

A

Vasomotion via:

Baroreceptor reflex- stretch detector

Chemoreceptor - chemical detector

CNS - Medulla oblongata - cardioinhibitory or cardioacceleratory

70
Q

Where are the baroreceptors located

A

Walls of large arteries, carotid sinuses, aortic arch

Sends to the brain via the glossopharyngeal nerve

** ineffective if altered BP is maintained. They adapt

71
Q

Where are the chemoreceptors located?

what is chemoreceptors primary role?

A

Aortic bodies, arch and large arteries of neck

detect increase in Co2, or drop in PH or 02

Primary - Adjust respiration to changes in blood chemistry

Secondary - vasomotion

72
Q

Medullary ischemic reflex does what

A

The hypothalamus increases bp during stress, anger and arousal

Hypothalamus mediates redistribution of blood flow during exercise and changes in body temp

73
Q

Medulla oblongata monitors its own..

A

blood supply

74
Q

What are the hormones that regulate blood pressure for short term?

A
  • *Adrenal** medulla - Epinephrine/norepinephrine - increases Co and vasoconstriction.
  • aldosterone - promotes Na+ and water retention by kidneys
  • *Angiotensin** II - Stimulates vasoconstriction- ^BP
  • *ADH**(Vasopressin) - promotes water retention - ^BP

atrial natriuretic peptide (ANP) - increases urinary sodium excretion, reduces blood volume and promotes vasodilation - decrease BP

75
Q

When binds to a-adrenergic receptors the result is

when bind to b adrenergic receptors the result is

A

a- adrenergic - vasoconstrict

b-adrenergic - vasodilate

76
Q

Long term mechanisms control BP by regulating

A

blood volume via kidneys

77
Q

Kidneys regulate arterial blood pressure by

A
  1. Direct renal mechanism (urine elimination or retention)
  2. Indirect renal mechanism (renin-angiotension-aldosternone)
78
Q

Decreased arterial blood pressure causes what to release from kidneys..

—– Enters blood and catalyzes the conversion of angiotensinogen from the liver to —–

A

Renin

Angiotensin I which gets converted to angiotensin II

79
Q

Angiotensin II acts in what 4 ways to stabilize arterial BP

A
  1. Stimulates aldosterone secretion
  2. Causes ADH to release from posterior pituitary
  3. Triggers hypothalamic thirst center
  4. Acts as a potent vasoconstrictor, directly increasing blood pressure
80
Q

Tissue perfusion is

A

Blood flow through body tissues at precisely right amount to provide proper function

involved in:
Delivery of O2, nutrients to and removal of waste
Gas exchange
Absorption of nutrients
Urine formation

81
Q

The rate of tissue perfusion is controlled by what extrinsic and intrinsic factors?

A

Extrinsic control - Sympathetic nervous system & hormones (reduce flow to regions that need it least)

Intrinsic control (local) - local arterioles undergo a modification of their diameters

82
Q

What are the 2 intrinsic mechanisms?

What does NO and endothelins do?

A

Metabolic - change in local chemicals - release NO or endothelins

Myogenic - Muscle - passive stretch or reduced stretch

NO - vasodilator

Endothelins - vasoconstrictor

83
Q

Syncope means?

What happens when your bp is above 160 mm Hg?

A

Fainting - Can happen below 60 mm Hg

Above 160 mm Hg can result in cerebral edema

84
Q

Speed of blood flow is related to cross sectional area. Capillaries have the largest area so they have the —– flow

A

Slowest - which allows for enough time for exchange between blood and tissues

85
Q

Molecules pass by —– between blood and interstitial fluid down their _______ ______.

What passes from blood to tissues?

What passed from tissues to blood?

A

Diffusion

Concentration gradient

Blood to tissues - O2 and nutrients

Tissues to blood - CO2 and metabolic waste

86
Q

What are the 4 different routes molecules use to cross capillary?

A
  1. Diffuse directly through endothelial membrane (except lipids)
  2. Pass through clefts (water soluble)
  3. Pass through fenestrations (water soluble)
  4. Active transport via pinocytotic vesicles or caveolae (proteins/larger molecules)
87
Q

Direction and amount of fluid exchange at capillaries depend on what 2 opposing forces?

A

Hydrostatic pressure

Colloid osmotic pressure

88
Q

What is hydrostatic pressure?

what are the 2 types?

A

Force exerted by fluid pressing against wall

Capillary (HPc) - bp that forces fluids through capillary walls, 35 - 17 mmHg

Interstitial (HPif) - pressure pushing fluid back into vessel, usually assumed a 0 bc lymphatic vessels drain interstitial fluid

89
Q

What are the 2 colloid osmotic pressures?

A

Capillary colloid osmotic pressure (OPc) 26 mmHg- Sucking pressure created by nondiffusible plasma proteins pulling water back into capillary

Interstitial fluid osmotic pressure (OPif) - pressure sucking from interstitial fluid. very little proteins so only around 1 mmHg

90
Q

Net filtration pressure (NFP) is what formula

Net fluid out at arterial end is?

Net fluid in at venous is?

A

NFP = (HPc-HPif) + (OPif-OPc)

Filtration

reabsorption

91
Q

What is edema?

what is it caused by?

A

Accumulation of excess fluid in a tissue (abnormal increase in amount of interstitial fluid)

occurs when fluid filters into a tissue faster than its absorbed

Caused by increase in outward pressure or decrease in inward pressure

92
Q

an increase is capillary hydrostatic pressure accelerates….

an increase in interstitial fluid osmotic pressure can result…

a decrease in capillary colloid osmotic pressure hinders…

A

fluid loss from blood

from an inflammatory response

fluid return to blood (reduced capillary absorption)

93
Q

Interstitial fluid in subcutaneous tissues generally causes

A
94
Q

What are the 3 main causes of edema?

A
  • *Increased capillary filtration**
  • Kidney failure, histamine release, old age, poor venous return
  • *Reduced capillary absorption**
  • Hypoproteinemia, liver disease, protein deficiency
  • *Obstructed lymphatic drainage**
  • surgical removal of lymph nodes
95
Q

What are the consequences of edema?

A

Tissue necrosis

pulmonary edema- suffocation threat

cerebral edema - headaches, nausea, seizures, coma

Severe edema or circulatory shock - low blood volume and pressure

96
Q
A
97
Q

What is hypertension?

A

Sustained elevated arterial pressure of 140/90 mm Hg or higher

Prehypertension is close to those numbers

Can be seen during fever, physical exertion and emotional upset. Common in obese people

Prolonged hypertension is cause of heart failure, vascular disease, renal failure and stroke

98
Q

What is hypotension?

Orthostatic hypotension?

Chronic hypotension?

Acute hypotension?

A

Below 90/60 mm Hg

temp low bp - suddenly rising too fast

chronic - poor nutrition warning sign for hyppthyroidism

acute - warning sign for circulatory shock

99
Q

Circulatory shock?

A

Abnormal perfusion

where blood vessels inadequately fill and cannot circulate blood normally; cannot meet tissue needs

100
Q

What is hypovolemic shock?

Vascular shock?

Cardiogenic shock?

Neurogenic shock?

Septic shock?

Anaphylactic shock?

A

hypovolemic shock - results from large scale blood loss

Vascular shock - results from extreme vasodilation

Cardiogenic shock - inefficient heart cannot sustain adequate circulation

Neurogenic shock - loss of vasomotor tone, vasodilation (emotional shock to brainstem injury)

Septic shock - bacterial toxins trigger vasodilation and increased capillary permeability

Anaphlyatic shock - severe immune reaction to antigen, histamine release, generalized vasodilation, increased capillary permeability

BIO 224 (20 decks)

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