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Anatomy & Physiology II > Blood Vessels > Flashcards

Blood Vessels Flashcards

1
Q

Where are the arteries and arterioles located?

A

deep in the body for protection

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2
Q

Which way do arteries flow?

A

carry blood away from the heart

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3
Q

What are the types of arteries?

A

elastic and muscular arteries

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4
Q

Elastic arteries characteristics

A
  • Located close to heart
  • Large diameter, lots of elastic fibers
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5
Q

What is the function of elastic arteries?

A

maintain pressure during ventricular diastole
- pressure reservoir = storage
- pressure gradient)

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6
Q

Elastic recoil

A

the ability of the arteries to expand and slowly return back to their original shape.

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7
Q

What are examples of elastic arteries?

A

aorta, common carotid, subclavian, pulmonary

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8
Q

Muscular arteries characteristics

A
  • Smaller diameter than elastic
  • Located further out from heart
  • Contain more smooth muscle, therefore not as stretchy
  • Thicker walls
  • Change diameter using muscle
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9
Q

Arterioles characteristics

A

Smaller than arteries

  • Microscopic (CAN NOT SEE with naked eye)

Control blood flow to tissue

  • Vasodilation
  • Vasoconstriction
  • Resistance vessels
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10
Q

In what order do blood vessels go in regard to size?

A

large to small and back again

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11
Q

What order do the blood vessels go in?

A

Arteries, arterioles, capillaries, venules, veins

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12
Q

What are the three layers of a blood vessels?

A
  • Tunica externa
  • Tunica media
  • Tunica intima
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13
Q

What type of tissue is the tunica media composed of?

A

smooth muscle (helps with vaso- processes)

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14
Q

What type of tissue is the tunica intima composed of?

A

endothelium tissue (simple squamous) and a basement membrane

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15
Q

Arteries characteristics

A

Arteries have thicker walls so that:
* Lumen of arteries is smaller
* Under higher pressure

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16
Q

Veins characteristics

A
  • Veins have valves
  • Under low pressure thus
  • Prevents backflow
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17
Q

Capillaries characteristics

A

Capillaries are composed of tunica intima
* Very thin walled
* For exchanges
* Smallest blood vessels

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18
Q

What are the three types of capillaries?

A
  • continuous capillaries
  • fenestrated capillaries
  • sinusoidal capillaries
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19
Q

Continuous capillaries

A
  • Most common
  • Small gaps between
    cells allow passage of
    fluid & small solutes
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20
Q

Fenestrated capillaries

A

Walls have pores
* Greater permeability
* Found in areas of
* High absorption (e.g.
intestines)
* Filtration (e.g.
kidney

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21
Q

Sinusoidal capillaries

A

Very leaky

  • Large gaps between
    cells
  • Found in bone
    marrow, liver, lymph
    and some endocrine
    tissue
  • Allow cells to cross

Blood flow is very
slow

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22
Q

What do capillaries from?

A

capillary beds

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23
Q

What controls blood flow in the capillaries/capillary beds?

A

pre-capillary sphincter

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24
Q

What is vasomotion?

A

the change in diameter of the blood vessels

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25
Q

What is the metarteriole?

A

A metarteriole is a short micro vessel in the microcirculation that links arterioles and capillaries.

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26
Q

Veins characteristics

A
  • Formed by joining of venules
  • Return blood to heart
  • Walls are very stretchy
  • Under very low pressure
  • Has valves that prevent backflow of blood
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27
Q

Veins act as what?

A

acts as a fluid reservoir: contains 60% of blood at rest

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28
Q

Define blood flow

A

volume of blood flowing through a
vessel, organ, or body per unit time (ml/min)

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29
Q

Define blood pressure

A

the force exerted on the walls of
vessels by the blood (mmHg)

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30
Q

How is blood pressure generated?

A

by the contraction of ventricles

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31
Q

Blood pressure is dependent on what?

A

blood volume

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32
Q

Pressure gradient

A

The tendency of blood to flow from an area of high to low pressure.

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33
Q

Where is pressure gradient the greatest and least?

A

Greatest near left ventricle, least in vena cavae

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34
Q

Define resistance

A

opposition to flow

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35
Q

What is friction in regards to blood vessels/blood flow?

A

Friction between blood and vessel wall

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36
Q

What are the three sources of resistance?

A
  • blood viscosity
  • total length of blood vessels
  • blood vessel diameter
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37
Q

Source of resistance: blood viscosity

A
  • As viscosity increases so does resistance
  • Is a function of the number of cells per unit volume
  • remains relatively constant
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38
Q

Source of resistance: total length of blood vessels

A

As length increases, so does resistance

  • Stays relatively constant
  • Weight gain can increase length
  • 200 miles/lb of fat
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39
Q

Source of resistance: blood vessel diameter

A
  • Not constant
  • Most important factor in determining resistance
  • smaller the diameter, the greater the resistance
  • More fluid in contact with the walls of the vessel
  • Capillaries have greatest resistance and large
    vessels have low resistance
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40
Q

How does vessel diameter change from artery to capillaries?

A

decreases

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41
Q

How does vessel diameter change from capillary to vein?

A

increases

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42
Q

Capillaries have the ______________ cross sectional area.

A

greatest

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43
Q

Larger vessels have the ______________ cross sectional area.

A

smallest

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44
Q

How does pressure change from arteries to veins?

A

decreases

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45
Q

Which type of vessel experiences the greatest drops in pressure?

A

arterioles

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46
Q

Why do arterioles experience the greatest drops in pressure?

A

because there needs to
be a drop in pressure before the blood reaches the capillaries so that they do not burst

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47
Q

Which vessels have the greatest luminal diameter?

A

the Vs (venules, veins, vena cava)

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48
Q

Which vessels have the greatest velocity of flow?

A

the As (Elastic arteries, muscular arteries, arterioles)

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49
Q

What is the relationship between the velocity of flow and the cross sectional area?

A
  • Decreases with increase in x sectional area
50
Q

Where is the velocity of flow the slowest?

A

in the capillaries

51
Q

Why is the velocity of flow the slowest in the capillaries? What does it aid in?

A
  • because exchanges take place in the capillaries so the slow flow of blood aids in the exchange process
52
Q

Where is the velocity of flow the greatest?

A

in the large vessels

53
Q

Why is the velocity of flow the greatest in the large vessels?

A
  • Speeds blood to capillaries
  • Assists in returning blood to heart in large veins
54
Q

Where is average blood pressure the greatest?

A

the elastic arteries

55
Q

Where is average blood pressure the smallest?

A

the vena cava

56
Q

What determines where the blood pressure is greatest and lowest?

A
  • blood pressure is greatest at the arteries because they are closest to the left ventricle pushing blood to the rest of the body
  • blood pressure is the lowest at the vena cava/veins because they are furthest from the pressure from the left ventricle in addition to the gravity acting on the body when blood tries to push blood back to the heart
57
Q

Arterial pressure is dependent on what?

A
  • How much the elastic arteries can be stretched
  • Blood volume
58
Q

Why is arterial pressure not constant?

A

As ventricle contract and eject blood, the arteries stretch causing an increase in pressure aka systolic pressure

59
Q

Why does blood flow away from the heart?

A

because of differences in
pressure

  • High in ventricle, low in veins
60
Q

How does ventricular diastole effect arterial pressure?

A

Semilunar valves shut to prevent backflow into
heart

Elastic recoil in aorta propels blood forward

61
Q

What is another name for arterioles?

A

pressure vessels

62
Q

The blood pressure in the arterioles drops to what before entering the capillaries?

A

35-40 mmHg

63
Q

What is the blood pressure at the ends of capillaries?

A

drops to 20 mmHg

64
Q

Why is low pressure required in the capillaries?

A
  • Capillaries are thin-walled
  • Capillaries are permeable to fluid even at low pressure
65
Q

What is venous pressure?

A

the blood pressure in the vena cava

66
Q

Why is venous pressure steady or not pulsatile?

A
  • Pressure gradient is low
    - Resistance is low
    - Increasing vessel diameter increases velocity
67
Q

What factors aid in venous return?

A

respiratory pump and muscular compressions

68
Q

Respiratory pump

A

Breathing causes low thoracic pressure

helps to pump blood back to the heart during inspiration. Inspiration increases the size of the thoracic cavity and decreases the pressure inside causing the pressure in the atria of the heart to drop to around 2.1 kPa, aspirating blood towards the right atrium from the thoracic vein.

69
Q

Muscular compressions

A
  • Skeletal muscles relax and contract forcing blood
    along (milking)
  • Blood cannot flow backwards due to valves in the veins
  • Most important of 2 mechanisms
70
Q

What three processes are involved in capillary exchange?

A

Diffusion
- Gases & small molecules

Transcytosis
* Large molecules

Bulk flow
* Filtration
* Reabsorption

70
Q

Bulk flow =

A

a process used by small lipid-insoluble proteins to cross the capillary wall

70
Q

Filtration =

A

pushed out

71
Q

Reabsorption =

A

pulled in

72
Q

Capillary exchange: define filtration

A

Movement of fluid and materials out of capillary due to pressure gradient
- Blood pressure is higher in the capillaries than tissue pressure

73
Q

Where does filtration occur?

A

on arteriole end of capillary

74
Q

Capillary exchange: define reabsorption

A

Movement of fluid back into capillaries due to osmotic pressure, caused by plasma proteins

75
Q

Blood colloid osmotic pressure

A

the osmotic pressure exerted by large molecules

76
Q

Reabsorption process:

A
  • As fluid leaves the capillaries due to filtration, capillary pressure decreases.
  • CAPILLARIES now have low pressure, and tissue have high pressure
  • Due to pressure gradient the blood flows from the tissues to the capillaries
  • Fluid from tissue enters capillaries by osmosis
77
Q

What three factors effect blood/control blood pressure?

A
  • Cardiac output
  • Peripheral resistance
  • Blood volume
78
Q

What factors can change cardiac output (CO)?

A
  • Change in heart rate
  • Change in stroke volume
  • Change in both
79
Q

What organ controls blood volume?

A

kidneys

80
Q

What are the kidneys capabilities on changing blood volume?

A
  • Can remove excess fluid if volume is too great
  • Cannot add fluid back if there has been loss
  • Can only prevent further loss
81
Q

What is the most influential/important factor when controlling blood pressure?

A

Peripheral resistance

82
Q

How is Peripheral resistance altered?

A
  • Altered by changing
    - diameter of blood vessels
    - distribution of blood between organs
83
Q

What two pathways are used to control Peripheral resistance?

A
  • Neural
  • Chemical
84
Q

What parts of the body are distributed the most blood at rest?

A

internal organs
- kidney
- digestive organs

85
Q

What parts of the body are distributed the most blood when active?

A
  • heart
  • skin
  • skeletal muscles
86
Q

What three factors are responsible for Neural Control of Peripheral Resistance?

A
  • Vasomotor center
  • Baroreceptor (pressure receptors) initiated reflex
  • Chemoreceptor initiated reflex
87
Q

Where is the vasomotor center located?

A

in cardiovascular center of medulla oblongata

88
Q

Vasomotor center function

A

Transmits signals along motor nerves to smooth muscle in blood vessels (tunica media)

89
Q

The vasomotor center is always doing what?

A

Always sending out signals. Thus, when a muscle is at rest it is slightly constricted.

90
Q

Vasomotor tone =

A

Muscles at “rest” are slightly constricted

91
Q

Increased and decreased activity levels in the vasomotor center?

A

Increase in activity level causes muscle to contract (vasoconstriction)

Decrease in activity causes muscles to relax (vasodilation)

92
Q

Baroreceptors are what kinds of receptors?

A

pressure receptors

93
Q

Where are baroreceptors located?

A

Pressure receptors located in elastic arteries

94
Q

What effect does an increase in pressure have on baroreceptors?

A
  • causes receptors to signal vasomotor center to decrease activity resulting in vasodilation (blood pressure decreases)
  • sends message to cardiac center to cause reduction in heart rate
95
Q

What effect does a decrease in pressure have on baroreceptors?

A
  • Causes opposite reaction
  • Receptors send signal to vasomotor, increasing activity, causing vasoconstriction
  • This causes an increase in blood pressure
96
Q

Baroreceptor initiated reflex protects against what?

A

helps protect body from rapid changes in blood pressure, such as occur during standing

97
Q

Chemoreceptors respond to what?

A

Respond to changes in O2 , CO2 , pH

98
Q

Where are chemoreceptors located?

A

located in carotids and aortic arch

99
Q

What chemical levels trigger chemoreceptors to send a signal to the vasomotor center to cause vasoconstriction?

A

Low O2 , high CO2 , or low pH

100
Q

When a blood vessel vasoconstricts what effect does it have on blood pressure?

A

Increases blood pressure speeding blood to heart and lungs

101
Q

What chemicals control the Chemical control of peripheral resistance?

A
  • Epinephrine and norepinephrine
  • Renin-Angiotensin-Aldosterone
  • Antidiuretic Hormone
  • Natriuretic peptides
  • NO (nitric oxide)
102
Q

Epinephrine and norepinephrine is secreted from where?

A

adrenal medulla

103
Q

Epinephrine and norepinephrine is part of what system?

A

sympathetic nervous system

104
Q

Epinephrine and norepinephrine affects the heart by doing what?

A

increasing CO

105
Q

How does Epinephrine and norepinephrine increase cardiac output (CO)?

A

Causes vasoconstriction of arterioles and blood vessels supplying digestive organs

Causes vasodilation in skeletal and cardiac muscle

Causes an overall increase in blood pressure

106
Q

Renin-Angiotensin-Aldosterone: How does the liver and kidneys respond to a decrease blood pressure?

A
  • liver secretes angiotensinogen in blood
  • kidney secretes renin into blood
107
Q

Angiotensinogen and renin in the blood cause the rise of what?

A

angiotensin II

108
Q

What are the effects of angiotensin II?

A
  • Vasoconstriction of arterioles
  • Release of Aldosterone and ADH
  • Increased water and Na+ reabsorption
  • Stimulates thirst
  • Functions to increase blood pressure
109
Q

Both Aldosterone and ADH cause what?

A
  • causes salt reabsorption = keeping more water = steady blood volume
  • both keep fluid in body
110
Q

What is the function of Antidiuretic Hormone (ADH)?

A
  • Stimulates kidneys to retain water
  • Causes vasoconstriction
  • Results in increase in blood pressure
111
Q

ADH responds to what chemical levels?

A
  • an increase in blood osmolarity,
  • decrease in volume,
  • increase in angiotensin II
112
Q

Natriuretic peptides is an antagonist to what chemicals?

A

Aldosterone and ADH

113
Q

Atrial natriuretic peptide (ANP) are produced by what?

A

both atria

114
Q

When is Atrial natriuretic peptide (ANP) released?

A

increases in blood volume

115
Q

What is the function of Natriuretic peptides/Atrial natriuretic peptide?

A

Lowers blood pressure

Vasodilation

Increases salt and water loss by kidneys

Suppresses ADH and aldosterone

116
Q

NO (nitric oxide) effects

A
  • Vasodilation
  • Effects are short lived
  • May be major factor in affecting blood pressure
117
Q

NO (nitric acid) is released by what?

A
  • Released by endothelial cells
118
Q

NO (nitric acid) is produced by what?

A
  • Produced by the tunica intima

Anatomy & Physiology II (13 decks)

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