The Circulatory system

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List the vessels of the microcirculation

ARTERIOLES, CAPILLARIES, VENULES

Name the 3 wall layers arteries and veins

TUNICA ADVENTITIA (EXTERNAL)
TUNICA MEDIA (MID LAYER)
TUNICA INTIMA (INNER)

What is the innermost tissue layer of arteries and veins? What type of cell composes this tissue layer? What characteristic does this tissue layer have? Why is this important?

TUNICA INTIMA
ENDOTHELIAL CELLS
CREATES A SMOOTH SURFACE OVER WHICH BLOOD FLOWS
INHIBITS PLATELET ACTIVATION AND REDUCES BLOOD CELL DAMAGE

Which vessel wall layer is innervated by sympathetic nerve fibers

TUNICA MEDIA

How do the walls of large vessels receive O2 and nutrients

VIA THE VASA VASORUM

How do arterial walls differ from vein walls

THEY ARE MUCH THICKER AND MORE RIGID

How does the tunica media layer of the aorta differ from that of smaller arteries and arterioles

IT CONTAINS LESS SMOOTH MUSCLE AND MORE ELASTIC FIBERS

What is the name of the vessel known as the major regulator of blood flow to systemic capillary beds

ARTERIOLE

Arteriolar smooth muscle function is regulated by 2 control mechanisms

SYMPATHETIC NERVOUS SYSTEM INPUT
LOCAL MECHANISMS

When blood vessels dilate, how does this affect tissue blood flow, vessel resistance to blood flow, and systemic blood pressure

TISSUE BLOOD FLOW INCREASES
VESSEL RESISTANCE DECREASES
SYSTEMIC BLOOD PRESSURE DECREASES

Capillaries consist of a single layer of which cell type

ENDOTHELIAL CELLS

Capillaries do NOT have a tunica media or tunica adventitia layer. Why is this important

THIN WALLS FACILITATE GAS DIFFUSION AND NUTRIENT TRANSPORT

Name the vessels that can function as thoroughfare channels in the circulatory system

METARTERIOLES

14. Briefly describe the function of pre-capillary sphincters

THEY RESPOND TO LOCAL BLOOD FLOW CONTROL SUBSTANCES BY CONSTRICTING OR RELAXING. WHEN CONSTRICTED, BLOOD FLOW IS ROUTED DOWN OTHER CAPILLARIES WHERE PRE-CAPILLARY SPHINCTERS ARE RELAXED AND/OR BLOOD FLOW IS ROUTED THROUGH METARTERIOLES DIRECTLY FROM ARTERIOLES TO VENULES

What percent of capillary beds are open at any given time in an individual at rest

25%

Describe vasomotion

AT REST, IT ALLOWS INTERMITTENT BLOOD FLOW THROUGH VARIOUS REGIONS OF TISSUE CAPILLARY BEDS SO TISSUE DOES NOT BECOME HYPOXIC

Where are venules located? They receive blood flow from which blood vessel

THEY ARE LOCATED AT THE VENOUS ENDS OF TISSUE CAPILLARIES AND RECEIVE BLOOD FROM TISSUE CAPILLARIES

List the 2 major characteristics of vein walls

THIN
DISTENSIBLE

Do vein walls contain smooth muscle

YES, BUT NOT AS MUCH AS ARTERIES

Which part of the circulatory system acts as a major blood reservoir

THE VENOUS CIRCULATION

Name the anatomic structure found in veins that insures one-way blood flow

VALVES

What is the mean systemic capillary blood pressure

17 mmHg

What is the normal blood pressure at the arteriolar end of a capillary

35 mmHg

What is the normal blood pressure at the venule end of a capillary

16 mmHg

List all 4 Starling forces that control fluid movement into and out of capillaries and briefly describe each one

BLOOD COLLOID OSMOTIC PRESSURE: PRESSURE EXERTED BY PLASMA PROTEINS
BLOOD HYDROSTATIC PRESSURE: PRESSURE CREATED BY ARTERIOLAR RESISTANCE AND "UPSTREAM" ARTERIAL BLOOD PRESSURE
INTERSTITIAL FLUID HYDROSTATIC PRESSURE: HYDROSTATIC PRESSURE WITHIN TISSUE INTERSTITIAL FLUID. IT IS USUALLY 0 mmHg.
INTERSTITIAL FLUID OSMOTIC PRESSURE: PRESSURE EXERTED BY PROTEIN MOLECULES WITHIN TISSUE INTERSTITIAL FLUID. THIS PRESSURE IS NORMALLY VERY LOW (< 1 mmHg)

Which 2 pressures named above promote filtration

BLOOD HYDROSTATIC PRESSURE
INTERSTITIAL FLUID OSMOTIC PRESSURE

Which 2 pressures named above promote reabsorption

BLOOD COLLOID OSMOTIC PRESSURE
INTERSTITIAL FLUID HYDROSTATIC PRESSURE

What is the normal net filtration pressure (NFP) at the arteriolar end of a capillary

10 mmHg

What is the normal NFP at the venule end of a capillary

- 9 mmHg

What is the overall NFP across a tissue capillary

+1 mmHg

Does the overall NFP favor filtration or reabsorption

IT FAVORS FILTRATION
THE COMBINED STARLING FORCES CAUSE APPROXIMATELY 20 LITERS OF PLASMA TO BE FILTERED INTO THE INTERSTITIAL SPACES FROM THE ARTERIOLAR END OF THE CAPILLARIES DAILY. OF THAT VOLUME, APPROXIMATELY 17 LITERS IS REABSORBED INTO THE VENULE END OF THE CAPILLARIES. THIS RESULTS IN FILTRATION OF APPROXIMATELY 3 LITERS OF PLASMA

What effect does plasma filtration from tissue capillaries have on interstitial fluid volume

IT INCREASES

Briefly explain how this fluid is returned to the blood circulation:

VOLUME NOT REABSORBED IS DRAINED FROM THE INTERSTITIAL SPACES BY THE LYMPHATIC SYSTEM AS LONG AS INTERSTITIAL FLUID VOLUME DOES NOT EXCEED THE CAPACITY OF LYMPHATIC DRAINAGE. THIS FLUID CIRCULATES THROUGH LYMPHATIC VESSELS AND ENTERS THE BLOOD CIRCULATION THROUGH THE THORACIC DUCT

Pathologic processes alter Starling forces. For each process below, indicate if Starling forces are favoring FILTRATION or REABSORPTION:
EDEMA

FILTRATION

Pathologic processes alter Starling forces. For each process below, indicate if Starling forces are favoring FILTRATION or REABSORPTION:
DEHYDRATION

REABSORPTION

List the 3 basic principles of circulatory function

A. TISSUE BLOOD FLOW IS CONTROLLED LOCALLY BASED ON O2 AND NUTRIENT REQUIREMENTS
B. NORMALLY CARDIAC OUTPUT IS REGULATED BY THE SUM OF ALL LOCAL TISSUE FLOWS IN ACCORDANCE WITH TISSUE O2 AND NUTRIENT REQUIREMENTS
C. ARTERIAL BLOOD PRESSURE IS REGULATED INDEPENDENTLY OF LOCAL BLOOD FLOW OR CARDIAC OUTPUT

Human circulatory function depends on the relationship between 3 physical factors

BLOOD FLOW
BLOOD PRESSURE
VASCULAR RESISTANCE

Write Ohm's law

Q = ∆P / R
Q= blood flow
∆P= pressure difference
R= vascular resistance

Considering Ohm's law, indicate the relationship between ∆P and vascular resistance

AS VASCULAR RESISTANCE INCREASES, ∆P DECREASES
AS VASCULAR RESISTANCE DECREASES, ∆P INCREASES

How is blood flow affected if P1 equals P2

BLOOD DOES NOT FLOW

In vessel #1: P1 = 100 mmHg and P2 = 70 mmHg
In vessel #2, P1 = 100 mmHg and P2 = 30 mmHg
In which vessel is blood flowing faster

VESSEL 2 (THERE IS A GREATER PRESSURE GRADIENT)

To insure that blood continues to flow at a specific rate, what must happen to the pressure gradient when vascular resistance increases

THE PRESSURE GRADIENT MUST INCREASE

According to Ohm's law, there is a linear relationship between pressure and flow; however, this cannot be applied to blood flow through vessels. Briefly explain why blood flow can increase 4-6X while blood pressure increases only 2X

INCREASED BLOOD PRESSURE DISTENDS VESSELS. VASCULAR RESISTANCE IS REDUCED.

Describe laminar flow

STREAMLINED FLOW (NORMALLY) OCCURRING IN LONG, SMOOTH VESSELS

Describe turbulent flow

CHAOTIC MIXING OF BLOOD STREAMS WITHIN A BLOOD VESSEL

List 3 factors that increase turbulent blood flow within blood vessels

INCREASED FLOW VELOCITY
INCREASED VESSEL DIAMETER
DECREASED BLOOD VISCOSITY

List pathologic causes of turbulent blood flow

ABNORMAL HEART VALVE STRUCTURE
ATHEROSCLEROSIS
COARCTATION OF THE AORTA
ANEMIA

What are Korotkoff sounds

THE SOUNDS PRODUCED BY INTENTIONALLY CREATING TURBULENT BLOOD FLOW IN THE LARGE ARTERIES OF THE ARM AS AN INFLATED BLOOD PRESSURE CUFF IS GRADUALLY DEFLATED. THE FIRST KOROTKOFF SOUND IS HEART THROUGH A STETHOSCOPE AS BLOOD (UNDER HIGH PRESSURE) BEGINS TO FLOW THROUGH PARTIALLY COMPRESSED ARTERIES (SYSTOLIC BLOOD PRESSURE). THE LAST KOROTKOFF SOUND IS HEARD JUST PRIOR TO TOTAL ARTERY DECOMPRESSION (DIASTOLIC BLOOD PRESSURE).

If you auscultate major arteries (listen through a stethoscope to carotid, abdominal aortic, iliac, renal, and femoral arteries) and hear sounds of turbulent blood flow, is this a NORMAL physical examination finding? Why or why not

NO. THIS USUALLY INDICATES NARROWING OF THE ARTERIAL LUMEN (MOST COMMONLY CAUSED BY CHOLESTEROL PLAQUES IN ARTERIAL WALLS)

Considering factors of Poiseuille's law discussed in class, name 2 factors that increase resistance to blood flow through vessels

BLOOD VESSEL DIAMETER
BLOOD VISCOSITY

Name the blood vessel that creates approximately 2/3 of the normal total systemic vascular resistance

THE SMALLEST ARTERIOLES

Blood flowing into an increased number of blood vessels oriented parallel to each other is expected to encounter increased or decreased vascular resistance? Why

VASCULAR RESISTANCE DECREASES
THE TOTAL CROSS-SECTIONAL AREA FOR BLOOD FLOW INCREASES

How does the normal narrow diameter of arterioles affect blood pressure and blood flow velocity through systemic capillaries

BLOOD PRESSURE IN SYSTEMIC CAPILLARIES IS LOW COMPARED TO ARTERIAL BLOOD
PRESSURE PROXIMAL TO THE ARTERIOLES
BLOOD FLOW VELOCITY IS SLOWER AS WELL

Blood viscosity is how many times greater than the viscosity of water

3 TIMES

why is it important for blood mpressure in the systemic capillaries to be low compared to arterial blood pressure

BLOOD FLOW THROUGH CAPILLARIES CANNOT BE TOO FAST. THERE MUST BE ENOUGH TIME TO ALLOW GAS DIFFUSION AND NUTRIENT TRANSPORT TO TISSUE CELLS

List 3 causes of increased hematocrit

POLYCYTHEMIA
BLOOD DOPING
DEHYDRATION

Up to 1 liter of intravenous fluid can normally be transfused rapidly without adverse effects on circulatory function. What is the primary physical characteristic of veins that allows this

VASCULAR DISTENSIBILITY

Large arteries like the aorta have very little compliance; however, the compliance they have serves 3 important functions. List them

A. DAMPENING OF THE PRESSURE PULSE WAVE (IN DISTAL ARTERIES)
B. FORWARD PROPULSION OF BLOOD
C. ENERGY ABSORPTION FROM LEFT VENTRICULAR EJECTION

Why is it important that damping of the pressure pulse wave occurs before it reaches systemic capillary beds

SO BLOOD FLOW THROUGH CAPILLARIES IS NON-PULSATILE (THIS ENHANCES GAS DIFFUSION)

Sympathetic stimulation of arteriolar walls has what effect on arteriolar diameter? What is the term for this change

IT DECREASES
VASOCONSTRICTION

Sympathetic stimulation IN VEINS, has what effect on venous return (VR)?

IT INCREASES VR

During exercise arterioles within skeletal muscles vasodilate, while at the same time arterioles in the GI tract and kidneys vasoconstrict. Blood preferentially flows to the skeletal muscles where arteriolar resistance to blood flow is lower. This process is known as

BLOOD TRANSLOCATION

List the terms that describe the normal state of partial vasoconstriction caused by continuous low-level sympathetic nervous system stimulation of blood vessels

VASCULAR TONE
VASOMOTOR TONE

During a significant hemorrhage, mass sympathetic discharge occurs. What effect does this have on all systemic blood vessels

THEY VASOCONSTRICT

Name the organ or tissue that has the highest priority for blood flow (esp in significant hemorrhage)

THE BRAIN

Sympathetic nervous system inhibition has what effect on systemic veins

THEY DILATE

Parasympathetic nerve fibers conduct impulses to which area(s) of the cardiovascular system

SA NODE
AV NODE
BOTH ATRIA
(ALSO TO VESSELS OF THE GENITALS, SALIVARY GLANDS, AND THE GI TRACT)

Describe stress-relaxation

INCREASED BLOOD VOLUME INITIALLY INCREASES INTRAVASCULAR PRESSURE. AFTER MINUTES TO HOURS, BLOOD VESSELS DISTEND TO ACCOMMODATE THE EXTRA VOLUME. BLOOD PRESSURE RETURNS TO BASELINE

Describe reverse stress-relaxation

DECREASED BLOOD VOLUME CAUSES VESSEL CONSTRICTION. THIS OCCURS TO KEEP BLOOD PRESSURE HIGH ENOUGH TO PERFUSE THE BRAIN AND OTHER VITAL ORGANS

stress relaxation and reverse stress relaxation describe a specific concept. Name it

DELAYED COMPLIANCE

Define pulse pressure

THE DIFFERENCE BETWEEN SYSTOLIC AND DIASTOLIC ARTERIAL BLOOD PRESSURE

List 2 situations that INCREASE (or widen) pulse pressure

INCREASED STROKE VOLUME
DECREASED ARTERIAL COMPLIANCE

Does stroke (blood) volume travel with pressure pulsations as they move down the aorta and branching arteries? Why or why not?

NO. THE WAVE OF PRESSURE AND DISTENTION TRAVELS JUST AHEAD OF THE NEW BLOOD VOLUME THAT WAS EJECTED INTO THE AORTA

Is mean arterial pressure (MAP) the average of systolic plus diastolic blood pressure? Why or why not?

NO. DIASTOLE MAKES UP APPROXIMATELY 60% OF THE CARDIAC CYCLE AT REST, SO THE MEAN PRESSURE IS CLOSER TO THE DIASTOLIC PRESSURE THAN THE SYSTOLIC PRESSURE.

Systolic blood pressure increases more than diastolic blood pressure or MAP with age. Why?

DECREASED COMPLIANCE OF THE AORTIC WALL
WHEN THE LEFT VENTRICLE EJECTS STROKE VOLUME INTO THE AORTA, THE DECREASED COMPLIANCE CAUSES THE SYSTOLIC PRESSURE TO BE HIGHER THAN IT WOULD BE IF THE AORTIC WALLS WERE MORE COMPLIANT.

What is considered a normal MAP?

> 60 mmHg

What is another name for central venous pressure (CVP)?

RIGHT ATRIAL PRESSURE

What is the normal range for CVP

0-4 mmHg

CVP regulation requires a balance between 4 factors. List them

A. THE MANNER IN WHICH BLOOD FLOWS FROM THE SYSTEMIC VEINS INTO THE RIGHT ATRIUM
B. THE COMBINED EFFORT OF THE RIGHT ATRIUM AND RIGHT VENTRICLE TO EJECT BLOOD INTO THE PULMONARY TRUNK AND LUNGS
C. NORMAL FUNCTION OF THE PULMONARY VASCULAR SYSTEM
D. THE COMBINED EFFORT OF THE LEFT ATRIUM AND LEFT VENTRICLE TO EJECT BLOOD INTO THE AORTA AND SYSTEMIC VESSELS

Arteriolar vasodiation plus increased vascular tone of large veins increase venous return (VR). What effect does this have on CVP

IT INCREASES (IN HEALTHY PEOPLE, THE CVP RETURNS TO NORMAL RAPIDLY)

MAP formula

diastolic + 1/3 pulse pressure
ex: BP 120/80
80 + 1/3 of 40 = 93 mmHg

If cardiac output (CO) equals venous return (VR), what is the CVP (normally)?

0-4 mmHg

how does RIGHT HEART PATHOLOGY increases CVP

CORONARY ARTERY DISEASE REDUCING RIGHT VENTRICULAR FUNCTION AND TRICUSPID OR PULMONIC VALVE DISEASE ALL CREATE A HIGHER RESISTANCE TO BLOOD FLOW FROM THE SYSTEMIC VEINS

how does RIGHT VENTRICULAR DYSFUNCTION 2° TO LUNG DISORDERS increases CVP

COPD, ARDS, AND PULMONARY EMBOLISM ALL CAUSE INCREASED PULMONARY VASCULAR RESISTANCE. THE RIGHT VENTRICLE CANNOT ADEQUATELY EJECT BLOOD INTO THE HIGHER RESISTANCE TO BLOOD FLOW IN THE LUNGS.

how does RIGHT HEART FAILURE 2° LEFT HEART FAILURE increases CVP

AORTIC AND MITRAL VALVE DISEASE AND CORONARY ARTERY DISEASE WITH DECREASED LEFT VENTRICULAR FUNCTION ALL CAUSE BLOOD TO BACK UP INTO THE LUNGS AND RIGHT HEART. IF THE CONDITION IS SEVERE ENOUGH, THE RIGHT VENTRICLE WILL FAIL BECAUSE IT CANNOT EJECT BLOOD INTO AN INCREASED AFTERLOAD.

how does LEFT HEART DISEASE - PERICARDIAL TAMPONADE, CONSTRICTIVE PERICARDITIS, AORTIC AND MITRAL VALVE DISEASE increase CVP

PERICARDIAL TAMPONADE AND CONSTRICTIVE PERICARDITIS COMPRESS THE HEART AND REDUCE VENTRICULAR FILLING. INCOMING BLOOD FROM THE LUNGS ENCOUNTERS INCREASED RESISTANCE TO BLOOD FLOW. AORTIC AND MITRAL VALVE DISEASE ALSO CREATE INCREASED RESISTANCE TO BLOOD FLOW. ALL OF THESE CONDITIONS CAUSE BLOOD TO BACK UP INTO THE LUNGS, RIGHT HEART, AND SYSTEMIC VEINS (DEPENDING ON HOW LONG THE CONDITION EXISTS).

How does intravascular fluid overload affect CVP?

IT INCREASES

There is an increased risk of volume overload in elderly patients. Why?

ELDERLY PERSONS HAVE DECREASED GFR ASSOCIATED WITH AGING. IF THE ELDERLY PATIENT ALSO HAS CO-MORBID RENAL INSUFFICIENCY ASSOCIATED WITH DIABETES AND/OR HYPERTENSION, THE RISK OF VOLUME OVERLOAD INCREASES EVEN MORE.

Can CVP be as low as - 3 to - 5 mmHg? If so, why?

YES. THIS OCCURS IN CONDITIONED ATHLETES WHEN CO EXCEEDS VR. THE SAME CAN OCCUR IN PATIENTS WITH SEVERE HEMORRHAGE

When CVP is > 4 mmHg, initially, there is no increase in peripheral venous pressure. Why?

VEINS THAT ARE NORMALLY COMPRESSED FILL WITH BLOOD AND DISTEND. PERIPHERAL VENOUS PRESSURE DOES NOT CHANGE AT THIS POINT.

What effect does pregnancy have on venous pressure within the legs?

IT INCREASES

What is the venous pressure in the feet of a person standing absolutely still?

90 mmHg

A person eventually loses consciousness (faints) if they continue to stand absolutely still. Why?

BLOOD POOLS IN THE LOWER EXTREMITIES BECAUSE THE VENOUS PUMP IS NOT WORKING.
BLOOD FLOW TO THE BRAIN DECREASES CAUSING BRAIN HYPOXIA.

What is the function of the venous pump?

IT PREVENTS BLOOD POOLING IN THE VEINS OF THE EXTREMITIES

Briefly explain how the venous pump works

AS A PERSON ACTIVELY MOVES HIS/HER LEGS (AND ARMS), MUSCLES ALTERNATELY CONTRACT AND RELAX PUSHING BLOOD TOWARD THE VENA CAVAE. VENOUS VALVES PREVENT RETROGRADE BLOOD FLOW IN THE VEINS

What effect does walking have on venous pressure in the feet?

IT REDUCES IT DRAMATICALLY FROM 90 mmHg TO 20 mmHg.

When a person stands at rigid attention, capillary pressure increases rapidly. Two events occur if the person stands too long. List them

PERIPHERAL EDEMA
HYPOTENSION AND FAINTING

List the etiologies of varicose veins

PREGNANCY
OBESITY
STANDING FOR WEEKS TO YEARS

How does pregnancy, obesity, and prolonged standing affect venous valves

THE VEINS ARE DAMAGED. PERMANENT DISTENTION OF THE VEINS IN AREAS WHERE VALVES ARE LOCATED PREVENTING THEM FROM CLOSING PROPERLY

Describe the appearance of varicose veins

ENLARGED, BULBOUS

In some patients with varicose veins, the accompanying interstitial edema may have adverse consequences. What are they and

LEG WEAKNESS AND PAIN
SKIN ULCERATION(S)

Pts with varicose veins may have leg weakness and pain and/or skin ulcerations, why does this occur

BOTH CONDITIONS OCCUR BECAUSE OF POOR BLOOD FLOW THROUGH THE CAPILLARIES. INADEQUATE GAS DIFFUSION AND NUTRIENT DELIVERY TO THE SOFT TISSUES OF THE LEGS CAUSES PAIN, WEAKNESS, AND SKIN ULCERS

List treatment strategies for varicose veins

A. ELEVATE LEGS TO HEART LEVEL
B. USE COMPRESSION STOCKINGS
C. LOSE WEIGHT
D. DELIVER BABY (INDUCED LABOR IS NOT NORMALLY PERFORMED AS A TREATMENT FOR VARICOSE VEINS)

How is CVP measured in hospitalized cardiac/critical care patients

A PRESSURE TRANSDUCER IS PLACED IN THE RIGHT ATRIUM. PRESSURE IS DISPLAYED ON A BEDSIDE MONITOR

How is CVP estimated in a sitting patient? What is another name for this procedure

BY OBSERVING NECK VEIN DISTENTION
JUGULAR VENOUS PULSATIONS

Is it normal for external neck veins to be distended in a patient who is supine with their head elevated 30-45 degrees? Why or why not

NO. THIS INDICATES THAT VENOUS RETURN IS ENCOUNTERING SOME TYPE OF RESISTANCE IN THE RIGHT HEART, LUNGS, OR LEFT HEART DUE TO A PATHOLOGIC PROCESS.

Explain how the respiratory pump works during inhalation:

DURING INHALATION, INTRA-ABDOMINAL PRESSURE INCREASES AND INTRA-THORACIC PRESSURE DECREASES. LARGE ABDOMINAL VEINS ARE COMPRESSED PUSHING BLOOD UPWARD INTO THE THORACIC VEINS THAT ARE NOT COMPRESSED.

What prevents blood from flowing back toward the lower extremities during exhalation

VENOUS VALVES

Normal respiratory pump function during strenuous exercise has what effect on venous return

IT INCREASES SIGNIFICANTLY

Each tissue controls its own blood flow according to

TISSUE METABOLIC REQUIREMENTS

How does local blood flow control by tissues benefit heart function

IT KEEPS CARDIAC WORKLOAD TO A MINIMUM

Low tissue O2 changes the diameter of some blood vessels. How

BLOOD VESSELS DILATE

Acute control of local blood flow is via vasoconstriction or vasodilation of 2 types of blood vessels. List them:

ARTERIOLES
METARTERIOLES

A structure of the microcirculation is affected by local blood flow control. Name it:

PRE-CAPILLARY SPHINCTERS

How rapidly does acute local control of blood flow to tissues occur?

WITHIN SECONDS TO MINUTES

Reference the O2/nutrient lack theory. When O2 and nutrient supply to tissues is inadequate, 3 events occur. List them

A. VASCULAR SMOOTH MUSCLE RELAXES
B. VESSELS DILATE
C. BLOOD FLOW INCREASES UNTIL THE DEFICIENCY IS CORRECTED

Formation of endogenous vasodilators in tissue cells occurs in response to

HYPOXIA OR INCREASED TISSUE METABOLISM

What effect do endogenous vasodilators have on arterioles, metarterioles, and pre-capillary sphincters? (be specific)

ENDOGENOUS VASODILATOR SUBSTANCES RELAX SMOOTH MUSCLE

What is the name of the substance that most physiologists believe is the most important endogenous vasodilator?

ADENOSINE

The vasodilator, adenosine, is very important in enhancing blood flow through the arteries of which organ?

THE HEART (MYOCARDIUM)

Briefly explain the roles hypoxia, ATP, and increased tissue metabolic activity have on release of adenosine from muscle cells:

INCREASED TISSUE METABOLISM WITH HYPOXIA CAUSES ADENOSINE RELEASE FROM TISSUE CELLS
METABOLICALLY ACTIVE TISSUES DEGRADE INCREASED AMOUNTS OF ATP AND THIS INCREASES ADENOSINE RELEASE FROM TISSUE CELLS

Describe active hyperemia:

BLOOD FLOW TO METABOLICALLY ACTIVE TISSUE INCREASES. TISSUES RELEASE INCREASED AMOUNTS OF VASODILATOR SUBSTANCES. THIS INSURES CONTINUED INCREASED BLOOD FLOW TO THESE TISSUES

Describe reactive hyperemia

THIS OCCURS WHEN BLOOD FLOW TO TISSUES IS OCCLUDED FOR AWHILE. ONCE THE OCCLUSION IS REMOVED, BLOOD FLOW TO THE TISSUES INCREASES SUBSTANTIALLY - UP TO 4-7 TIMES NORMAL. THE INCREASED FLOW CONTINUES UNTIL THE TISSUE O2 AND NUTRIENT DEFICIT IS CORRECTED

Briefly describe autoregulation of blood flow

AUTOREGULATION RETURNS TISSUE BLOOD FLOW ALMOST TO BASELINE AFTER AN INCREASE IN ARTERIAL BLOOD PRESSURE

Briefly describe metabolic autoregulation:

INCREASED TISSUE BLOOD FLOW DELIVERS TOO MUCH O2. THIS CAUSES LOCAL VASOCONSTRICTION

Briefly describe myogenic autoregulation

STRETCHING OF TISSUE BLOOD VESSELS CAUSED BY INCREASED BLOOD FLOW CAUSES MOMENTARY CONSTRICTION OF VASCULAR SMOOTH MUSCLE. BLOOD FLOW DECREASES TO NEAR BASELINE. AKA REACTIVE VASOCONSTRICTION

Briefly explain why "upstream" arteries vasodilate when local tissue blood flow increases

THERE IS INCREASED SHEAR STRESS ON UPSTREAM BLOOD VESSELS WHEN TISSUE BLOOD FLOW INCREASES. UPSTREAM VESSELS PRODUCE NITRIC OXIDE IN RESPONSE TO THE SHEAR STRESS. THIS VASODILATES UPSTREAM VESSELS ALLOWING MORE BLOOD FLOW TO TISSUE VESSELS

Another name for nitric oxide is:

ENDOTHELIUM-DERIVED RELAXING FACTOR

Define long-term blood flow regulation

SLOW, CONTROLLED BLOOD FLOW CHANGES OVER A PERIOD OF DAYS, WEEKS, OR MONTHS

If 75% of tissue blood flow is restored after LOCAL blood flow mechanisms are activated, why is it important that long-term blood flow control mechanisms be activated

LOCAL CONTROL MECHANISMS FOR BLOOD FLOW ARE ONLY TEMPORARY MEASURES

How do tissues compensate for chronic (long-term) tissue hypoxia and nutrient deficiency?

THE SIZE AND NUMBERS OF ARTERIOLES AND CAPILLARIES SERVING THAT TISSUE INCREASE

Do new vessels that grow into tissue become a permanent part of that tissue's vascular structure? Why or why not

NO. IF THE TISSUE NO LONGER REQUIRES INCREASED BLOOD FLOW, THESE VESSELS ATROPHY.

New vessel construction occurs rapidly in what type(s) of tissue(s)

NEW-GROWTH TISSUE: SCARS, SOME CANCEROUS TUMORS, NEONATES

New vessel construction in older tissue occurs much slower. Are these new vessels normally able to provide adequate O2 and nutrients to metabolically active tissue(s)

NO

Briefly describe how angiogenic factors work:

THEY STIMULATE NEW VESSEL GROWTH FROM EXISTING BLOOD VESSELS

What stimulates release of angiogenic factors?

CHRONICALLY DECREASED TISSUE O2 AND NUTRIENT DELIVERY

List 3 major angiogenic factors:

VEGF: VASCULAR ENDOTHELIAL GROWTH FACTOR
FIBROBLAST GROWTH FACTOR
ANGIOGENIN

What is the purpose for growth of collateral blood vessels?

LONG-TERM BLOOD FLOW REGULATION AROUND A VASCULAR OBSTRUCTION

Do collateral vessels supply a near-normal blood supply to tissues during any activity level? Why or why not?

NO. THEY ARE NOT STRUCTURALLY ABLE TO SUPPLY HIGH BLOOD FLOWS

List 5 major vasoconstrictor substances

NOREPINEPHRINE
EPINEPHRINE
ANGIOTENSIN II
VASOPRESSIN
ENDOTHELIN

List 2 primary effects that norepinephrine has on the cardiovascular system

INCREASED HEART RATE
VASOCONSTRICTION OF VEINS AND SOME ARTERIOLES

What is the primary effect that epinephrine has on coronary arteries?

VASODILATION DURING PERIODS OF INCREASED HEART ACTIVITY

Is angiotensin II considered a local vasoconstrictor? Why or why not?

NO. ITS EFFECTS ARE SYSTEM-WIDE

What effect does vasopressin have and what is the result of vasopressin activity in an individual who has experienced a significant hemorrhage?

VASOPRESSIN IS NOT NORMALLY A MAJOR VASOCONSTRICTOR SUBSTANCE. IN SIGNIFICANT HEMORRHAGE, VASOPRESSIN ACTIVITY CAN INCREASE ARTERIAL BLOOD PRESSURE BY APPROXIMATELY 60 mmHg

What stimulates endothelin release? Does it exert local or systemic effects

ENDOTHELIN IS RELEASED WHEN THE ENDOTHELIAL LAYER OF BLOOD VESSELS IS DAMAGED IN SOME WAY. THE EFFECTS ARE LOCAL.

Name the 2 vasodilator substances commonly released during allergic reactions

HISTAMINE AND BRADYKININ

Stimulatory impulses from which of the nerve fiber types DOMINATES while a person is exercising

VASODILATOR

indicate the effect(s) that an increased ECF concentration of CALCIUM has on the vascular system

VASOCONSTRICTION

indicate the effect(s) that an increased ECF concentration of POTASSIUM has on the vascular system

VASODILATION

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