Chapter 20- Cardiovascular

Question 1

Layers of the Arteries

Answer 1

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)

Question 2

Elastic Arteries

Answer 2

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.

Question 3

Muscular Arteries

Answer 3

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

Question 4

Arterioles

Answer 4

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

Question 5

Capillaries

Answer 5

Microscopic blood vessels, walls of thin tunica intima

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

Question 6

Function of Capillaries

Answer 6

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

Question 7

Venules

Answer 7

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

Question 8

Veins

Answer 8

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

Question 9

Venous Sinus

Answer 9

Flatten veins with extremely thin walls

Question 10

Venous Valves

Answer 10

Prevent backflow of blood

Question 11

Anastomoses

Answer 11

Alternative pathway to given body region

Question 12

Factors that affect the physiology of circulation

Answer 12

Blood Flow
Blood Pressure
Resistance

Question 13

Blood Flow

Answer 13

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

Question 14

Blood Pressure

Answer 14

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.

Question 15

Resistance

Answer 15

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

Question 16

3 Factors that affect Resistance

Answer 16

Viscosity
Blood Vessel Length
Blood Vessel Diameter

Question 17

Viscosity

Answer 17

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

Question 18

Blood Vessel Length

Answer 18

Longer Vessel = Greater resistance encountered

Question 19

Blood Vessel Diameter

Answer 19

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

Question 20

Pericytes

Answer 20

support walls, control permeability

Question 21

Arterial blood pressure reflects two factors of arteries close to heart

Answer 21

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

Question 22

Systolic pressure

Answer 22

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

When DR. Listening, is pressure when sounds first occur

Question 23

Diastolic pressure

Answer 23

lowest aortic pressure

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

Question 24

Pulse pressure

Answer 24

systolic - diastolic

Question 25

Mean arterial pressure (MAP)

Answer 25

pressure that propels blood to tissues | MAP = diastolic pressure + 1/3 pulse pressure (BP = 120/80; MAP = 93 mm Hg)

Question 26

Capillary blood pressure

Answer 26

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

Question 27

Venous blood pressure

Answer 27

Small gradient; about 15 mm Hg | Low pressure due to cumulative effects of peripheral resistance

Question 28

Factors Aiding Venous Return

Answer 28

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

Question 29

Maintaining Blood Pressure

Answer 29

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

Question 30

Chemoreceptor Reflexes

Answer 30

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

Question 31

Hormonal Controls

Answer 31

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

Question 32

Direct Renal Long-Term Mechanism

Answer 32

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

Question 33

Indirect Renal

Answer 33

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

Question 34

Pulse

Answer 34

expansion and recoil of arteries

Question 35

Pressure points

Answer 35

arteries close to surface

Question 36

How is Pressure Measured

Answer 36

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

Question 37

Hypertension

Answer 37

Sustained elevated arterial pressure of 140/90 or higher

Question 38

Prehypertension

Answer 38

if values elevated but not yet in hypertension range | May be transient or persistent.

Question 39

Why Hypertension is bad

Answer 39

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

Question 40

Secondary hypertension

Answer 40

due to obstructed renal arteries, kidney disease, endocrine disorders

Question 41

Hypotension

Answer 41

Blood pressure below 90/60 mm Hg | Usually not a concern, only if leads to inadequate blood flow to tissues

Question 42

Orthostatic hypotension

Answer 42

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

Question 43

Chronic hypotension

Answer 43

hint of poor nutrition and warning sign for endocrine disorders

Question 44

Acute hypotension

Answer 44

sign of circulatory shock; threat for surgical and ICU patients

Question 45

Tissue perfusion

Answer 45

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)

Question 46

Order of strongest blood pressure to lowest blood pressure

Answer 46

``` Aorta Arteries Arterioles Capillaries Venules Veins Venae Cavae ```

Question 47

Autoregulation

Answer 47

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

Question 48

Autoregulation: Metabolic Controls

Answer 48

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

Question 49

Autoregulation: Myogenic Controls

Answer 49

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

Question 50

Intrinsic Vasodilators

Answer 50

``` -- Metabolic -- Reduced O2 Increased CO2 Increased H+ Increased K+ • Prostaglandins • Adenosine • Nitric oxide ```

Question 51

Intrinsic Vasoconstrictors

Answer 51

``` Myogenic = Stretch Metabolic = Endothelins ```

Question 52

Extrinsic Vasodilators

Answer 52

Neuronal - Decrease Sympathetic Tone | Hormonal - Atrial natriuretic peptide

Question 53

Extrinsic Vasoconstrictors

Answer 53

[ Maintain mean arterial pressure (MAP) & Redistribute blood during exercise and thermoregulation ] ``` Neuronal - Increase Sympathetic Tone Hormonal • Angiotensin II • Antidiuretic hormone • Epinephrine • Norepinephrine ```

Question 54

Angiogenesis

Answer 54

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

Question 55

Blood Flow: Skeletal Muscles

Answer 55

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

Question 56

Blood Flow: Brain

Answer 56

``` 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 60 mm Hg can cause syncope (fainting) - MAP above 160 can result in cerebral edema

Question 57

Blood Flow: Skin

Answer 57

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

Question 58

Blood Flow: Lungs

Answer 58

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

Question 59

Blood Flow: Heart

Answer 59

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

Question 60

During Strenuous exercise

Answer 60

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

Question 61

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

Answer 61

Hydrostatic and Colloid Osmotic Pressure

Question 62

Hydrostatic pressure

Answer 62

Tends to force fluids through capillary walls | Greater at arterial end (35 mm Hg) of bed than at venule end (17 mm Hg)

Question 63

Interstitial fluid hydrostatic pressure

Answer 63

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

Question 64

Colloid osmotic pressure

Answer 64

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

Question 65

Net Filtration Pressure (NFP)

Answer 65

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

Question 66

Hypovolemic shock

Answer 66

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.

Question 67

Vascular shock

Answer 67

from extreme vasodilation and decreased peripheral resistance

Question 68

Cardiogenic shock

Answer 68

results when an inefficient heart can’t sustain adequate circulation

Question 69

3 Types of Capillaries

Answer 69

* 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.

Question 70

Ischemia

Answer 70

blood pressure too low to pump blood sufficiently

Question 71

Hypoxia

Answer 71

inadequate oxygenation of tissues do to ischemia

Question 72

Skeletal Muscle Pump

Answer 72

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