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Chapter 20 Flashcards

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1
Q

Name the layers of veins and arteries

A

tunica Interna
Tunica media
Tunica externa

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2
Q

Which is the innermost layer of the tunicas?

A

Tunica interna

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3
Q

Which is the middle layer of the tunicas?

A

tunica media

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4
Q

Which is the outermost layer of the tunics?

A

tunica externa

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5
Q

Explain the anatomy and physiology of the tunica interna

A

Lines the blood vessel and is exposed to blood.

Simple squamous endothelial overlying basement membrane and sparse layer of loose connective tissue allows rapid exchange.

Acts as a selectively permeable barrier
secretes chemicals that Stimulate vasodilation and constriction

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6
Q

Explain the anatomy and physiology of the tunica media

A

middle layer
Consists of smooth muscle collagen and elastic tissue.
Strengthens blood vessels and prevents blood pressure from rupturing them
Regulates diameter of the blood vessel
Pump of the blood vessel

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7
Q

Explain the anatomy and physiology of the tunica externa

A

outermost layer
Loose connective tissue that often merges with neighboring blood vessels, nerves and organs
Anchors vessel and provides passage for nerves and lymphatic vessels
Vasa vasorum, small vessels that supply blood to larger vessels

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8
Q

What are vasa vasorum

A

small blood vessels found in the tunica externa that supply the larger blood vessels with blood

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9
Q

What is the difference between the anatomy of veins and arteries?

A

The tunica media of the arteries are much thicker than the tunica media of the veins

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10
Q

Place the following in the correct order

Large vein
Conducting artery
Venule
Capillary
Distributing,medium artery
Medium vein
Arteriole
A 
conducting,large artery
Distributing, medium artery
Arteriole
Capillary
Venule
Medium vein
Large vein
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11
Q

Why are arteries sometimes called resistance vessels

A

because of their strong resilient tissue structure

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12
Q

What are the size classifications of arteries?

A

Conducting arteries, large
Distributing arteries, medium
Arteriole small
Metarterioles

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13
Q

Name some of the conducting elastic large arteries

A 
aorta
Common carotid
Subclavian
Pulmonary  trunk
Common iliac
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14
Q

Explain physiology of conducting elastic artery

A

expand during systole, recoil during diastole.
Expansion takes pressure of smaller downstream vessels
Recoil maintains pressure during relaxation and keeps pressure flowing

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15
Q

Explain anatomy of conducting arteries

A

have a layer of elastic tissues internal elastic laminate at the border between lamina internal and media

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16
Q

Name some of the distributing arteries

A

brachial
Femoral
Renal
Splenic

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17
Q

Explain anatomy of distributing arteries

A

smooth muscle layers constitute three fourths of wall thickness

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18
Q

Explains the physiology of distributing arteries

A

Distributes blood to specific organs

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19
Q

Name the resistance arteries

A

arterioles

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20
Q

Explain the physiology of resistance arteries

A

control amount of blood to various organs

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21
Q

Explain the anatomy of resistance arteries

A

thicker tunica media in proportion to their lumen than large arteries and very little tunica externa

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22
Q

What are metarterioles

A

short vessels that link Arteriole to capillaries

Muscle cells form pre capillary sphincter around the entrance to the artery

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23
Q

What is the function of the pre capillary sphincter?

A

to direct blood towards the tissue by opening or to constrict, directing blood away and along the thoroughfare channel

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24
Q

What is an aneurysm?

A

weak point in artery or heart wall
Forms a thin wall bulging sac that pulsates with each
heartbeat and may rupture at any time

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25
Q

What is a dissecting aneurysm?

A

When blood accumulates between the tunica of an artery and separates them. Usually because of degeneration of tunica media

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26
Q

What are the most common sites of aneurysms.

A

abdominal aorta
Renal arteries
Arterial circle at base of brain

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27
Q

what are the causes if an aneurysm?

A

Atherosclerosis and hypertension.
Congenital weakness of blood vessels
Trauma
Bacterial infections

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28
Q

What is the function if chemoreceptors?

A

detect fluctuations in PH usually due to CO2 fluctuations

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29
Q

What are arterial sense organs

A

sensory structures in walls of major vessels that monitor blood pressure and chemistry. They transmit I formation to the brainstem to regulate heart rate, blood pressure, vessel diameter and respiration

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30
Q

What is the function of baroreceptors?

A

Detect fluctuations in blood pressure

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31
Q

What are the carotid sinuses?

A 
baroreceptors
In walls of internal carotid artery
Monitor blood pressure
Transmit signals through glossopharyngeal nerve
Allow baroreflex
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32
Q

What are carotid bodies

A

chemoreceptors
Oval bodies near branch of common carotids
Monitor blood chemistry
Transmit signals through glossopharyngeal nerve to brainstem respiratory centers
Adjust respiratory rate to stabilize PH CO2 and O2

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33
Q

What are aortic bodies

A

chemoreceptors
One to three bodies in aortic arch
Innervated by vagus nerve

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34
Q

Explain how the composition of capillary walls differs from that of other blood vessels.

A

Capillary walls consist only of endothelial and basal laminar. This makes exchange more rapid as they are the business end of the cardiovascular system.

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35
Q

What are the three types of capillaries?

A

Continuous capillaries
Fenestrated capillaries
Sinusoid/noncontinuous

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36
Q

Explain the anatomy and physiology of a continuous Capillary

A

occur in most tissues
Endothelial cells have tight junctions forming a continuous tube with intercellular clefts.
Because the clefts are so small, they allow only passage of the smallest solutes such as water and glucose.
Pericytes, peripheral to the endothelial cells wrap around the capillaries and contain the same contractile protein as muscle so they can contract and regulate blood flow.

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37
Q

Explain the anatomy and physiology of a fenestrated Capillary

A

found in organs where rapid absorption or filtration is needed. The endothelial cells are rich with filtration pores called fenestrations. Spanned by a very thin glycoprotein layer and allow passage of only small molecules.

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38
Q

Explain the anatomy and physiology of a sinusoid

A

Have large fenestrations that can allow entire cells, proteins such as albumins and clotting factors to pass through them.

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39
Q

Most common site of a fenestrated capillary

A

kidneys and small intestine

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40
Q

Most common site of a sinusoid

A

liver, bone marrow and spleen

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41
Q

How many capillaries make up a capillary bed

A

a network of 10-100

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42
Q

What are capillary beds supplied by?

A

A single arteriole or metarteriole

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43
Q

At the distal end of the capillary bed…

A

capillaries transition to venules or drain into the thoroughfare channel

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44
Q

How is bloodflow through the capillary bed controlled?

A

The control of bloodflow through the capillary bed involves constriction of arterioles that are upstream from the capillaries. Bloodflow is usually dependent upon the need of tissues or organs. Once the blood reaches the capillary bed, precapillary sphincters control flow. When sphincters are relaxed, capillaries are well perfused with blood. When sphincters contract, they constrict entry to the capillary and blood continues along the thoroughfare channel.

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45
Q

Where is the majority of blood found and what is the percentage?

A

Veins

54%

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46
Q

what are postcapillary venules?

A

the smallest veins

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47
Q

explain the anatomy and physiology of postcapillary venules

A

More porous than capillaries so also exchange fluid with surrounding tissues
Tunica interna with a few fibroblasts and no muscle fibers
most leukocytes emigrate from the bloodstream through venule walls

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48
Q

What are muscular venules?

A

veins that are up to 1mm in diameter
have one or two layers of smooth muscle in tunica media
thin tunica externa

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49
Q

What are medium veins?

A

veins up to 10mm in diameter
Thin tunica media and thick tunica externa
Tunica interna forms venous valves

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50
Q

What are varicose veins?

A

Blood pools in the lower legs of people who stand for long periods stretching the veins
cusps of the valves pull apart in enlarged superficial veins further weakening
blood backflows and further extends the vessels

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51
Q

What are venous sinuses?

A

Veins with especially thin walls. large lumens and no smooth muscle.
Not capable of vasomotor responses

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52
Q

Name the types of venous sinuses

A

Dural venous sinus and coronary sinus of the heart

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53
Q

What are large veins?

A

veins with a diameter of 10mm and above
contain some smooth muscle in all three tunics
Thin tunica media with moderate amount if smooth muscle
Tunica externa is the thickest layer containing longitudinal bundles of smooth muscle

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54
Q

Name some large veins

A

Venae Cavae, Pulmonary veins, internal jugular veins and renal veins

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55
Q

What are hemorrhoids?

A

Varicose veins of the anal canal

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56
Q

Common causes of varicose veins

A

Hereditary weakness, obesity and pregnancy

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57
Q

What are the circulatory routes?

A

Simple
Portal system
Anastomoses

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58
Q

Describe the simple circulatory route

A

Heart-arteries-arterioles-capillaries-venules-veins

Passes through only one set of capillaries from when it leaves the heart and returns

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59
Q

Describe the Portal system

A

Passes through two consecutive capillary beds between leaving the heart and returning

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60
Q

Anastomosis

A

Convergence point between 2 vessels other than capillaries.

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61
Q

Types of anastomosis

A

Arteriovenous (shunt)
Venous anastomosis
Arterial anastomosis

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62
Q

Arteriovenous anastomosis

A

Artery flows directly into vein, bypassing capillaries

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63
Q

venous anastomosis

A

most common
one vein empties directly into another
reason vein blockage is less serios than arterial blockage

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64
Q

Arterial anastomosis

A 
2 arteries merge
provides collateral (alternative) routes of blood supply to a tissue
coronary circulation and common around the joints
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65
Q

Blood flow

A

The amount of blood flowing through an organ, tissue or blood vessel in a given time (mL/min)

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66
Q

Perfusion

A

the flow per given volume or mass of tissue in a given time (mL/min/g)

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67
Q

What is resting blood flow

A

5.25 L/min and is equal to cardiac output

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68
Q

Importance of blood flow

A

important for delivery of nutrients and O2 and removal of metabolic wastes

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69
Q

Hemodynamics

A

study of bloodflow

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70
Q

Formula for physical principles of blood flow

A

F(flow)= AP(difference in pressure)/R(resistance)

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71
Q

Principle of blood flow

A

The greater the pressure difference between two point the greater the flow.
The greater the resistance, the less flow

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72
Q

What is blood pressure?

A

The force that blood exerts against a vessel wall

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73
Q

How is blood pressure measured?

A

At the brachial artery of the arm using a sphygmomanometer

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74
Q

Which two pressures are recorded when determining blood pressure?

A

Systolic pressure

Diastolic pressure

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75
Q

What is systolic pressure?

A

Peak arterial BP taken during ventricular contraction (Ventricular systole)

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76
Q

What is diastolic pressure?

A

minimum arterial pressure taken during ventricular relaxation (diastole) between heartbeats

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77
Q

Normal blood pressure for a young adult

A

120/75 mm Hg

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78
Q

What is pulse pressure?

A

Difference between systolic and diastolic pressure

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79
Q

why is pulse pressure important?

A

It is an important measure of driving force on circulation and of stress exerted on small arteries by pressure surges generated by the heart

80
Q

What is mean arterial pressure

A

the mean pressure obtained by taking measurements at several intervals throughout the cardiac cycle

81
Q

Blood flow in arteries is

A

pulsatile

82
Q

Blood flow in capillaries and veins

A

flows at steady speed

83
Q

BP rises with age - true or false

A

true

84
Q

Why does blood pressure rise with age?

A

Arteriosclerosis- stiffening of arteries

atherosclerosis- build up of lipid deposits

85
Q

What is hypertension?

A

chronic resting blood pressure of over 140/90

resulting in weakening of arteries, aneurysms and atherosclerosis

86
Q

What is hypotension

A

Chronic resting BP of less than 120/75 usually caused by blood loss, dehydration and anemia

87
Q

What is arteriosclerosis

A

stiffening of arteries causing blood pressure to rise

88
Q

What is atherosclerosis

A

build up of lipid deposits resulting in clogging of artery

89
Q

What are the determining factors of Blood pressure?

A

Cardiac output, blood volume and resistance to flow

90
Q

How is blood volume regulated

A

kidneys

91
Q

what happens to blood pressure as we get further from the heart?

A

it gets lower

92
Q

Where is blood pressure highest?

A

Aorta/ Arterial system

93
Q

Where is blood pressure lowest?

A

Venae Cavae/Venous system

94
Q

What is peripheral resistance?

A

The opposition of flow that blood encounters in vessels away from the heart

95
Q

What are the three variables in peripheral resistance?

A

Blood viscosity
Vessel length
Vessel radius

96
Q

How does blood viscosity affect peripheral resistance?

A

RBC count and albumin concentration elevate viscosity slowing flow
Decreased viscosity with anemia and hypoproteinemia speeding up flow

97
Q

How does vessel length affect peripheral resistance?

A

The farther liquid passes through a tube, the more cumulative friction it encounters. Pressure and flow therefore decline with distance

98
Q

How does Vessel radius affect peripheral resistance?

A

Vasoconstriction and vasodilation expand and contract vessel radius markedly affecting blood velocity.

99
Q

Which factor is the most powerful influence over flow?

A

Vessel radius

100
Q

What are vasoreflexes?

A

changes in vessel radius controlled by the tunica media

101
Q

Explain laminar flow

A

Blood in the centre experiences less friction than blood in the periphery against vessel walls. So the wider the vessel the less friction and the greater the flow

102
Q

Why does blood velocity decrease between the aorta and the capillaries?

A

Greater distance, more friction to reduce speed
Smaller radii of arterioles and capillaries offers more resistance
Farther from the heart, the number of vessels and their total cross sectional area become greater and greater

103
Q

Why does blood velocity increase again between capillaries and vena cava?

A

Veins are larger so create less resistance than capillaries

104
Q

Which vessels are the most significant point of contract over peripheral resistance and flow?

A

Arterioles because they are positioned on proximal end of capillary beds and best positioned to regulate flow into the capillaries
more muscular in proportion to their diameter
outnumber any other type of artery

105
Q

How much of peripheral resistance do arterioles produce

A

Half

106
Q

what are the three ways of controlling vasomotor activity?

A

Local control
Neural control
Hormonal control

107
Q

List the local methods of vasomotor control

A

Autoregulation
Vasoactive chemicals
reactive hyperemia
angiogenesis

108
Q

what is autoregulation?

A

The ability of tissues to regulate their own blood supply.
metabolic theory of autoregulation:
inadequately perfused tissues results in wastes accumulating stimulating vasodilation. bloodstream delivers o2 and removes metabolites
vessels constrict

109
Q

What are vasoactive chemicals in local control?

A

substances secreted by platelets, endothelial cells and perivascular tissue to stimulate vasomotor responses

110
Q

Examples of vasoactive chemicals

A

Histamine
Bradykinin
prostaglandins

111
Q

What is reactive hyperemia

A

Local vasomotor control. If blood supply is cut off then restored, flow increases above normal

112
Q

What is angiogenesis

A

growth of new blood vessels controlled by growth factors and inhibitors

113
Q

Where does angiogenesis occur

A

regrowth of uterine lining
around coronary artery obstructions
exercised muscle
malignant tumors

114
Q

Which Nervous systems does vasomotor control concern?

A

Central and autonomic nervous system (ANS)

115
Q

Where in the brain is the vasomotor centre located?

A

Medulla oblongata

116
Q

does the medulla oblongata exert sympathetic or parasympathetic control over blood vessels?

A

sympathetic

117
Q

Does the vasomotor centre stimulate all vessels to constrict?

A

Most, but it dilates vessels in cardiac muscle to meet demands of exercise

118
Q

The vasomotor centre is the integrating centre for which autonomic reflexes?

A

Baroreflexes
Chemoreflexes
Medullary ischemic reflex

119
Q

what is a baroreflex?

A

An automatic negative feedback response to change in blood pressure detected in carotid artery
glossopharyngeal nerve sends the signal to the brain
Govern short term regulation of BP

120
Q

What is a chemoreflex?

A

an automatic response to changes in blood chemistry

PH, Co2 and O2 especially

121
Q

What are chemoreceptors?

A

aortic bodies and carotid bodies located in the aortic arch, subclavian arteries and external carotid arteries

122
Q

What is the primary role of chemoreceptors?

A

adjust respiration in response to changes in blood chemistry

123
Q

What is the secondary role of chemoreceptors?

A

vasoreflexes

124
Q

What is the medullary Ischemic reflex?

A

automatic response to drop in blood perfusion of the brain.

125
Q

How is medullary Ischemic reflex triggered?

A

Medulla oblongata monitors its own blood supply and activates corrective reflexes when ischemia is detected

126
Q

What other factors can trigger the vasomotor centre?

A

stress
anger
arousal

127
Q

what is hormonal control of vasomotor activity?

A

influence on blood pressure with either vasoactive effects or regulation water balance

128
Q

What is Angiotensin II?

A

A potent vasoconstrictor
raises blood pressure and volume
promotes NA+ and water retention by kidneys

129
Q

What is Atrial netriuretic peptide (ANP)

A

Increases urinary sodium excretion
reduces blood volume and pressure
promotes vasodilation

130
Q

What is ADH?

A

promotes water retention and raises BP

pathologically high concentrations are aslo a vasoconstrictor

131
Q

What is the effect of epinephrine and norepinephrine on blood vessels?

A

They promote Vasoconstriction of most blood vessels and vasodilation of the cardiac muscle vessels at the same time

132
Q

what are the two main purposes of vasoreflexes?

A

General control of BP

Routing blood from one region to another

133
Q

How is blood flow rerouted in response to needs?

A

Arteries shift blood flow with changing needs

134
Q

what is capillary exchange?

A

2 way movement of fluid across capillary walls

135
Q

Name some of the things being exchanged in capillary exchange

A

water oxygen glucose immunoacids carbon dioxide wastes

136
Q

Name the routes chemicals pass through capillary walls

A

endothelial cytoplasm
intercellular clefts between endothelial cells
filtration pores of the fenestrated capillaries

137
Q

name the mechanisms involved in capillary exchange

A

Diffusion
Transcytosis
filtration
Reabsorption

138
Q

Which is the most important form of capillary exchange?

A

Diffusion

139
Q

What happens in capillary diffusion?

A

Glucose and O2 being more concentrated in the blood diffuse out of the blood and in to the tissue fluid.
Co2 and other waste being more concentrated in tissue fluid diffuse in to the blood

140
Q

Which substances can pass through the plasma membrane during capillary diffusion?

A

Lipid soluble substances

141
Q

Which substances must pass through filtration pores or intercellular clefts during capillary diffusion?

A

Glucose and electrolytes

142
Q

Which substances cannot enter the blood via capillary diffusion?

A

large particles such as proteins

143
Q

Which substances must be exchanged via transcytosis during capillary exchange?

A

fatty acids, albumin and some hormones such as albumin

144
Q

What is the process of filtration in capillary exchange

A

Fluid filters out of the arterial end of the capillary

145
Q

What is the process of reabsorption in capillary exchange?

A

fluid osmotically re-enters the capillary at the venous end

146
Q

What is Blood hydrostatic pressure?

A

It drives fluid out of the capillary. It is high on the arterial end and low on the venous end

147
Q

What is Colloid osmotic pressure (COP)

A

draws fluid in to the capillary . Results from plasma proteins being more in the blood

148
Q

What is oncotic pressure ?

A

blood cop-tissue cop

149
Q

What percentage of fluid to capillaries reabsorb?

A

85%

150
Q

What happens to the 15% of fluid not reabsorbed by capillaries?

A

it is absorbed by the lymphatic system and returned to the blood

151
Q

What is net filtration pressure (NFP)?

A

hydrostatic pressure - COP

152
Q

At which end of the capillary bed does filtration occur?

A

Arterial end

153
Q

At which end of the capillary bed does reabsorption occur?

A

Venous end

154
Q

What is Edema?

A

accumulation of excess fluid in a tissue as a result of fluid entering a tissue faster than it is absorbed

155
Q

What are the primary causes of edema?

A

Increased capillary filtration
Reduced capillary absorption
obstructed lymphatic drainage

156
Q

What is tissue necrosis?

A

O2 delivery and waste removal impaired

157
Q

What is Pulmonary edema

A

suffocation threat

158
Q

what is Cerebral edema

A

Headaches, seizures, nausea and coma

159
Q

What is Severe edema/circulatory shock?

A

Excess fluid in tissue spaces causing low blood volume and low blood pressure

160
Q

What is venous return?

A

The flow of blood back to the heart

161
Q

What does venous return rely on?

A 
Pressure gradient
Gravity
skeletal muscle pump
thoracic pump
cardiac suction
162
Q

What is the significance of pressure gradient in venous return?

A

Blood pressure is the most important force in venous return

163
Q

What is the role of gravity in venous return?

A

drains blood from head and neck

164
Q

What is the role of the skeletal muscle pump in venous return?

A

located in the limbs

contracting muscle squeezes blood out of the compressed part of the vein

165
Q

What is the role of the thoracic (respiratory) pump in venous return?

A

during inhalation, the thoracic cavity expands and thoracic pressure decreases, abdominal pressure increases, forcing blood upwards

166
Q

What is the role of cardiac suction in venous return?

A

expanding of the arterial space creates suction and assists in venous return

167
Q

Name some of the ways exercise increases venous return

A

Heart beats faster and harder increasing Cardiac output and BP
Vessels of muscles lungs and heart dilate
Increased respiratory rate means increased action of thoracic pump
increased activity of skeletal muscle pump

168
Q

What is venous pooling?

A

pooling of blood that is not returned via venous return due to inactivity

169
Q

What is circulatory shock?

A

any state in which cardiac output is insufficient to meet the body’s needs

170
Q

what are the types of circulatory shock?

A

Cardiogenic shock

Low venous return

171
Q

What is cardiogenic shock?

A

Inadequate pumping of the heart (MI)

172
Q

What is Low venous return? (LVR)

A

Cardiac output is too low because too little blood is returning to the heart

173
Q

what are the three principal forms of LVR shock?

A 
Hypovolemic shock 
Obstructed venous return shock
Venous pooling (Vascular shock)
174
Q

What are the causes of Hypovolemic shock?

A

Loss of blood volume, trauma, burns, dehydration

175
Q

what is the cause of obstructed venous return shock?

A

Tumor or aneurysm obstructing a vein

176
Q

What are the causes of venous pooling (vascular) shock?

A

Long periods of standing, sitting or widespread vasodilation

177
Q

What is Neurogenic shock?

A

Loss of vasomotor tone leading to vasodilation

178
Q

What is septic shock?

A

Bacterial toxins trigger vasodilation and increased capillary permeability

179
Q

What is anaphylactic shock?

A

Severe immune reaction to antigen, histamine release, generalized vasodilation, increased capillary permeability

180
Q

What are the responses to circulatory shock?

A

Compensated shock

Decompensated shock

181
Q

What is compensated shock?

A

several homeostatic mechanisms bring about spontaneous recovery

182
Q

What is decompensated shock?

A

When compensation fails
Life threatening positive feedback loops occur
can be fatal

183
Q

Blood flow to the brain fluctuates —————-than that of any other organ

A

Less

184
Q

What happens to the brain after seconds of blood deprivation?

A

loss of consciousness

185
Q

What happens to the brain after 4-5 minutes of blood deprivation?

A

irreversible brain damage

186
Q

Which organ regulates blood flow to the brain?

A

The brain

187
Q

How does the brain regulate blood flow?

A

Cerebral arteries dilate as systemic BP drops and constrict as BP rises

188
Q

What is the main chemical stimulus for brain regulation of blood flow?

A

PH

189
Q

What is hypercapnia?

A

Co2 levels increase in brain, PH decreases triggering vasodilation

190
Q

What is hypocapnia?

A

raised PH stimulates vasoconstriction (occurs for example with hyperventilation)

191
Q

What is a stroke (CVA)?

A

Sudden death of brain tissue caused by ischemia

192
Q

What are the two main circulatory pathways?

A

Pulmonary circulation

Systemic circulation

193
Q

What is the Pulmonary circulation?

A

A short loop that runs from heart to lungs and back to heart

194
Q

What is the systemic circulation?

A

A long loop to all parts of the body and back to the heart

195
Q

Which ventricle belongs to the systemic circuit

A

Left

196
Q

which atrium receives blood from the systemic circuit?

A

Right

197
Q

which ventricle has the thickest myocardium?

A

Left

Bio 151 (12 decks)

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