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Anatomy & Physiology > Chapter 20- Cardiovascular > Flashcards

Chapter 20- Cardiovascular Flashcards

1
Q

Layers of the Arteries

A 
Lumen (middle, blood flow) 
Tunica Intima (Endothelium, subendothelial layer, internal elastic membrane)
Tunica Media (Smooth Muscle and elastic fibers, external elastic membrane)
Tunica Externa (Vasa Vasorum)
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2
Q

Elastic Arteries

A

Large thick-walled arteries with elastin. Aorta and major branches. Large lumen offers low-resistance pressure reservoirs, Expand and recoil as blood ejected from heart.

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3
Q

Muscular Arteries

A

Distal to elastic arteries. Thick tunica media with more smooth muscle. Active in Vasoconstriction.

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4
Q

Arterioles

A

Smallest arteries leading to capillary beds, control flow into capillary beds via vasodilation and vasoconstriction.

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5
Q

Capillaries

A

Microscopic blood vessels, walls of thin tunica intima

Pericytes support their walls, control permeability, in all tissues except for cartilage, epithelia, cornea and lens

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6
Q

Function of Capillaries

A

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

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7
Q

Venules

A

Formed when capillary beds unite,porous, allow fluids and WBC’s into tissues, consist of endothelium and a few pericytes

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8
Q

Veins

A

Return blood to heart for reoxygenation, thinner walls, larger lumens, lower blood pressure than arteries

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9
Q

Venous Sinus

A

Flatten veins with extremely thin walls

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10
Q

Venous Valves

A

Prevent backflow of blood

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11
Q

Anastomoses

A

Alternative pathway to given body region

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12
Q

Factors that affect the physiology of circulation

A

Blood Flow
Blood Pressure
Resistance

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13
Q

Blood Flow

A

Volume of blood flowing in a given period of time (ml/min) = (CO cardio output) Relatively constant when at rest

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14
Q

Blood Pressure

A

Force per unit area exerted on wall of blood vessel by blood - provides driving force that keeps blood moving from higher to lower pressure area.

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15
Q

Resistance

A

Opposition to flow measure of amount of friction blood encounters with vessel walls, generally in peripheral (systemic) circulation.

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16
Q

3 Factors that affect Resistance

A

Viscosity
Blood Vessel Length
Blood Vessel Diameter

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17
Q

Viscosity

A

Stickiness of blood due to formed elements and plasma proteins, increased viscosity = increased resistance

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18
Q

Blood Vessel Length

A

Longer Vessel = Greater resistance encountered

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19
Q

Blood Vessel Diameter

A

Greatest influence on resistance, varies inversely with 4th power of radius (if radius is doubled, resistance is 1/16) Vasoconstriction = increased resistance.

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20
Q

Pericytes

A

support walls, control permeability

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21
Q

Arterial blood pressure reflects two factors of arteries close to heart

A

Elasticity (compliance or distensibility)
Volume of blood forced in them time
Blood pressure near heart is pulsatile

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22
Q

Systolic pressure

A

pressure exerted in aorta during ventricular contraction
Averages 120 mm Hg in normal adult

When DR. Listening, is pressure when sounds first occur

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23
Q

Diastolic pressure

A

lowest aortic pressure

When Dr. Listening, is pressure when sounds disappear as blood flows freely

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24
Q

Pulse pressure

A

systolic - diastolic

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25
Q

Mean arterial pressure (MAP)

A

pressure that propels blood to tissues

MAP = diastolic pressure + 1/3 pulse pressure (BP = 120/80; MAP = 93 mm Hg)

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26
Q

Capillary blood pressure

A

Low is desirable because high BP would rupture thin-walled capillaries
Most very permeable, so low pressure forces filtrate into interstitial spaces

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27
Q

Venous blood pressure

A

Small gradient; about 15 mm Hg

Low pressure due to cumulative effects of peripheral resistance

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28
Q

Factors Aiding Venous Return

A

Muscular pump: contraction of skeletal muscles “milks” blood toward heart; valves prevent backflow

Respiratory pump: pressure changes during breathing move blood toward heart by squeezing abdominal veins as thoracic veins expand

Venoconstriction under sympathetic control pushes blood toward heart

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29
Q

Maintaining Blood Pressure

A 
Requires
• Cooperation of heart, blood vessels, and kidneys
• Supervision by brain
Main factors influencing blood pressure
• Cardiac output (CO)
• Peripheral resistance (PR)
•Blood volume
30
Q

Chemoreceptor Reflexes

A

Chemoreceptors in aortic arch detect increase in CO2, drop in pH or O2
Cause increased blood pressure by
Signaling cardioacceleratory center increase CO
Signaling vasomotor center increase vasoconstriction

31
Q

Hormonal Controls

A

Cause increased blood pressure
Epinephrine and norepinephrine increased CO and vasoconstriction
Angiotensin II stimulates vasoconstriction
High ADH levels cause vasoconstriction

32
Q

Direct Renal Long-Term Mechanism

A

Alters blood vol. independent of hormones
•Increased BP or blood volume causes elimination of more urine, reducing BP
•Decreased BP or blood volume causes kidneys to conserve water, and BP rises

33
Q

Indirect Renal

A 
Angiotensin II increases blood volume
Stimulates aldosterone secretion
Causes ADH release
Triggers hypothalamic thirst center
Causes vasoconstriction increasing blood pressure
34
Q

Pulse

A

expansion and recoil of arteries

35
Q

Pressure points

A

arteries close to surface

36
Q

How is Pressure Measured

A

BP measured indirectly by auscultatory method using a sphygmomanometer
Pressure increased in cuff until it exceeds systolic pressure in brachial artery
Pressure released slowly and listen for sounds of Korotkoff with a stethoscope

37
Q

Hypertension

A

Sustained elevated arterial pressure of 140/90 or higher

38
Q

Prehypertension

A

if values elevated but not yet in hypertension range

May be transient or persistent.

39
Q

Why Hypertension is bad

A

Prolonged hypertension big cause of heart or renal failure, vascular disease, stroke
Heart must work harder myocardium enlarges, weakens, becomes flabby
Also accelerates atherosclerosis

40
Q

Secondary hypertension

A

due to obstructed renal arteries, kidney disease, endocrine disorders

41
Q

Hypotension

A

Blood pressure below 90/60 mm Hg

Usually not a concern, only if leads to inadequate blood flow to tissues

42
Q

Orthostatic hypotension

A

temporary low BP and dizziness when suddenly rising from sitting or reclining position

43
Q

Chronic hypotension

A

hint of poor nutrition and warning sign for endocrine disorders

44
Q

Acute hypotension

A

sign of circulatory shock; threat for surgical and ICU patients

45
Q

Tissue perfusion

A

involved in
• Delivery of O2 and nutrients to, and removal of wastes from, tissue cells
• Gas exchange (lungs)
• Absorption of nutrients (digestive tract)
• Urine formation (kidneys)

46
Q

Order of strongest blood pressure to lowest blood pressure

A 
Aorta
Arteries
Arterioles
Capillaries
Venules
Veins Venae Cavae
47
Q

Autoregulation

A

Automatic adjustment of blood flow to each tissue relative to needs
Controlled intrinsically by modifying diameter of local arterioles feeding capillaries

48
Q

Autoregulation: Metabolic Controls

A

Vasodilation of arterioles and relaxation of precapillary sphincters occur in response to:
Declining tissue O2 and substances from metabolically active tissues (H+, K+, adenosine, prostaglandins), inflammatory chemicals
Effects
• Relaxation of vascular smooth muscle
• Release of NO (powerful vasodilator)
• Endothelins released from endothelium are potent vasoconstrictors

49
Q

Autoregulation: Myogenic Controls

A

Tissue perfusion constant despite most fluctuations in systemic pressure, stretch
• Passive stretch promotes vasoconstriction
•Reduced stretch promotes vasodilation

50
Q

Intrinsic Vasodilators

A 
-- Metabolic --
Reduced O2
 Increased CO2
 Increased H+
 Increased K+
• Prostaglandins
• Adenosine 
• Nitric oxide
51
Q

Intrinsic Vasoconstrictors

A 
Myogenic = Stretch
Metabolic = Endothelins
52
Q

Extrinsic Vasodilators

A

Neuronal - Decrease Sympathetic Tone

Hormonal - Atrial natriuretic peptide

53
Q

Extrinsic Vasoconstrictors

A

[ Maintain mean arterial pressure
(MAP) & Redistribute blood during exercise
and thermoregulation ]

Neuronal - Increase Sympathetic Tone
Hormonal 
• Angiotensin II
• Antidiuretic hormone
• Epinephrine
• Norepinephrine
54
Q

Angiogenesis

A

Number of vessels to region increases and existing vessels enlarge
Coronary vessel included, or in people in high-altitude areas, exercise

55
Q

Blood Flow: Skeletal Muscles

A

At rest, myogenic and neural mechanisms predominate ~ 1L /minute
• Active or exercise hyperemia - blood flow increases in direct
• Local controls override sympathetic vasoconstriction
• Muscle blood flow can increase 10

56
Q

Blood Flow: Brain

A 
Constant as neurons intolerant of ischemia; averages 750 ml/min
Metabolic controls
↓ pH of ↑ CO2 cause vasodilation
Myogenic controls
↓ MAP, cerebral vessels to dilate 
↑ MAP, cerebral vessels constrict

Brain vulnerable under extreme pressure changes - MAP below 60mm Hg can cause syncope (fainting) - MAP above 160 can result in cerebral edema

57
Q

Blood Flow: Skin

A

Supplies nutrients to cells, O2 needs
Provides a blood reservoir
Helps regulate body temperature

58
Q

Blood Flow: Lungs

A

Pulmonary circuit unusual: Path is short, arteries like veins (thin walls, large lumens), Arterial resistance and pressure are low

Autoregulatory mechanism opposite: Low O2 levels cause vasoconstriction; high levels promote vasodilation

59
Q

Blood Flow: Heart

A

Ventricular systole: vessels are compressed
• Myocardial blood flow ceases
• Stored myoglobin supplies oxygen
During diastole high aortic pressure forces blood through coronary circulation

60
Q

During Strenuous exercise

A

During strenuous exercise coronary vessels dilate in response to local accumulation of vasodilators
• Blood flow may increase 3-4 times
•Cardiac cells use 65% of O2 delivered, increased blood flow provides more O2

61
Q

Direction and amount of flow within capillaries depends on 2 Opposing Forces

A

Hydrostatic and Colloid Osmotic Pressure

62
Q

Hydrostatic pressure

A

Tends to force fluids through capillary walls

Greater at arterial end (35mmHg) of bed than at venule end (17mmHg)

63
Q

Interstitial fluid hydrostatic pressure

A

Pressure that would push fluid into vessel, Usually 0 due to lymphatic vessels

64
Q

Colloid osmotic pressure

A

Created by non-diffusible plasma proteins, which draw water toward themselves ~26 mm Hg

65
Q

Net Filtration Pressure (NFP)

A

The outward pressure minus the inward pressure or Hydrostatic Pressure minus Colloid osmotic pressure

66
Q

Hypovolemic shock

A

Hypovolemic shock is a result of severe blood loss. It will cause the blood vessels to constrict in an attempt to increase venous return and the heart will increase the rate of pumping blood as it attempts to make up for the low blood pressure and blood not getting throughout the body.

67
Q

Vascular shock

A

from extreme vasodilation and decreased peripheral resistance

68
Q

Cardiogenic shock

A

results when an inefficient heart can’t sustain adequate circulation

69
Q

3 Types of Capillaries

A
  • continuous - most common, in all vascular tissue, complete endothelial lining with tight junctions intermixed with intercellular clefts
  • fenestrated - has pores and clefts, found in intestinal lining, choroid plexus, and endocrine glands
  • sinusoid - swiss cheese and flattened, found in the liver and spleen, bone marrow, lymph nodes (where they carry lymph, not blood), and many endocrine glands including the pituitary and adrenal glands.
70
Q

Ischemia

A

blood pressure too low to pump blood sufficiently

71
Q

Hypoxia

A

inadequate oxygenation of tissues do to ischemia

72
Q

Skeletal Muscle Pump

A

In many body regions, the pressure within the veins can be increased by the contraction of the surrounding skeletal muscle.

Anatomy & Physiology (26 decks)

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