Capillaries consist of a single layer of which cell type
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
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
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
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
What is the mean systemic capillary blood pressure
What is the normal blood pressure at the arteriolar end of a capillary
What is the normal blood pressure at the venule end of a capillary
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)
What is the normal net filtration pressure (NFP) at the arteriolar end of a capillary
What is the normal NFP at the venule end of a capillary
- 9 mmHg
What is the overall NFP across a tissue capillary
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
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
Pathologic processes alter Starling forces. For each process below, indicate if Starling forces are favoring FILTRATION or REABSORPTION: DEHYDRATION
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
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
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
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
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
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
Name the organ or tissue that has the highest priority for blood flow (esp in significant hemorrhage)
Sympathetic nervous system inhibition has what effect on systemic veins
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)
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
Define pulse pressure
THE DIFFERENCE BETWEEN SYSTOLIC AND DIASTOLIC ARTERIAL BLOOD PRESSURE
List 2 situations that INCREASE (or widen) pulse pressure
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
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)
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)?
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?
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?
What is the venous pressure in the feet of a person standing absolutely still?
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
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
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:
A structure of the microcirculation is affected by local blood flow control. Name it:
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)
What is the name of the substance that most physiologists believe is the most important endogenous vasodilator?
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)
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
Name 3 tissues whose blood vessels receive parasympathetic innervation:
SALIVARY GLANDS GI TRACT (INCREASED SECRETIONS) GENITAL ERECTILE TISSUE
Name the regions of the heart innervated by parasympathetic nerve fibers
SA NODE, AV NODE, ATRIAL MYOCARDIUM
Through which nerve do parasympathetic impulses travel to the SA node, AV node, and atrial myocardium?
How is heart function affected when parasympathetic stimulation of the SA node, AV node, and atrial myocardium predominates?
HEART RATE AND MYOCARDIAL CONTRACTILITY DECREASE
List the organs/tissues that possess more sympathetic vasoconstrictor nerve fibers than the rest of the circulation
KIDNEYS INTESTINES SKIN SPLEEN
The normal function of body temperature regulating systems works toward preventing
Blood in skin capillaries flows into what structure
A VENOUS PLEXUS
Describe arteriovenous anastomoses in the skin. What is their function
THEY ARE VERY SMALL ARTERIES THAT TRANSPORT BLOOD FROM SKIN CAPILLARIES TO THE VENOUS PLEXUS. THEY ARE LOCATED IN THE HANDS, FEET, AND EARS
When the body core temperature increases, vasodilation of vessels transporting blood to skin capillaries occurs. What causes this vasodilation
INHIBITION OF SNS CENTERS IN THE HYPOTHALAMUS
Smooth muscle in three (3) vessels within the skin relaxes when body core temperature increases causing vasodilation of the vessels that transport blood to the skin. Name them
ARTERIES ARTERIOLES ARTERIOVENOUS ANASTOMOSES
The vasomotor center in the brain sends sympathetic output to which blood vessels (3)
ARTERIES ARTERIOLES VEINS
briefly describe Vasoconstrictor area function (vasomotor center)
SENDS EXCITATORY OUTPUT TO SYMPATHETIC NEURONS. INNERVATED BLOOD VESSELS CONSTRICT
briefly describe the Vasodilator area function (vasomotor center)
SENDS INHIBITORY OUTPUT TO THE VASOCONSTRICTOR AREA. SYMPATHETICALLY INNERVATED BLOOD VESSELS DILATE
briefly describe the Sensory area function (vasomotor center)
RECEIVES SENSORY INPUT FROM THE CIRCULATION VIA THE VAGUS AND GLOSSOPHARYNGEAL NERVES. OUTPUT SIGNALS REGULATION FUNCTION OF THE VASOCONSTRICTOR AND VASODILATOR AREAS
What effect does vasoconstriction have on heart rate and myocardial contractility
What effect does vasodilation have on heart rate and myocardial contractility?
Complete the equation: ARTERIAL BLOOD PRESSURE =
ARTERIAL BLOOD PRESSURE = CARDIAC OUTPUT X SYSTEMIC VASCULAR RESISTANCE
List and briefly describe the 3 major circulatory changes that INCREASE arterial blood pressure so more O2 and nutrients can be provided to tissues
A. ALMOST ALL ARTERIOLES IN THE SYSTEMIC CIRCULATION CONSTRICT B. VEINS AND OTHER LARGE VESSELS CONSTRICT C. THE SNS DIRECTLY STIMULATES THE HEART INCREASING HEART RATE AND MYOCARDIAL CONTRACTILITY
How is parasympathetic input to the heart affected when the cardioaccelerator and vasoconstrictor areas of the vasomotor system are activated
PARASYMPATHETIC INPUT TO THE HEART IS OVERRIDDEN
Outgoing sympathetic nerve impulses from the cardioaccelerator and vasoconstrictor areas can increase arterial blood pressure rapidly. To what extent and how rapidly
UP TO 2 TIMES NORMAL IN APPROX 5-10 SECONDS
Name the stretch receptors located within the carotid sinus
Name the stretch receptors located in the aortic arch
In what other locations are stretch receptors located?
WITHIN THE WALLS OF LARGE ARTERIES IN THE NECK AND THORAX
Briefly explain how the baroreceptor reflex DECREASES arterial blood pressure
INCREASED BLOOD PRESSURE STRETCHES BARORECEPTORS. RECEPTORS SEND IMPULSES TO THE VASOMOTOR CENTER. VASOCONSTRICTOR AREA FUNCTION IS INHIBITED. FEEDBACK IMPULSES TO THE HEART AND CIRCULATION (SYMPATHETIC INHIBITION) DECREASES HEART RATE, MYOCARDIAL CONTRACTILITY, AND CAUSES VASODILATION. BLOOD PRESSURE DECREASES.
Briefly explain how the baroreceptor reflex prevents a sudden decrease in arterial blood pressure within the head when a person stands up from a supine position:
THE REFLEX STIMULATES STRONG SYMPATHETIC NERVE STIMULATION THROUGHOUT THE BODY PRODUCING RAPID AND BRIEF DIFFUSE SYSTEMIC VASOCONSTRICTION PREVENTING CEREBRAL HYPOTENSION AND FAINTING
How does age affect the baroreceptor reflex
IT SLOWS WITH AGE
In a healthy person, minute-by-minute variations in arterial blood pressure are kept within the normal range by the baroreceptor reflex. Why is this important?
MEAN ARTERIAL PRESSURE IS MAINTAINED SO ORGANS ARE ADEQUATELY PERFUSED PHYSICAL STRESS ON BLOOD VESSELS IS MINIMIZED
Where are "low pressure" receptors located
IN THE WALLS OF THE PULMONARY ARTERIES AND BOTH ATRIA
What effect does increased blood volume within the "low pressure" area of the circulation have on heart rate and cardiac output
How is the "volume reflex" mechanism activated?
INCREASED BLOOD VOLUME
Name the substance released when the volume reflex mechanism is activated:
ATRIAL NATRIURETIC PEPTIDE (ANP)
Briefly explain how the REVERSE STRESS-RELAXATION reflex regulates RENAL FUNCTION
ANP DILATES KIDNEY AFFERENT ARTERIOLES CAUSING GLOMERULAR CAPILLARY PRESSURE TO INCREASE AND GFR TO INCREASE. ADH SYNTHESIS AND RELEASE ALSO DECREASES. THIS INCREASES URINE OUTPUT
The CNS ischemic response dramatically increases arterial blood pressure. To what extent can the response increase the mean arterial pressure (MAP)
UP TO 250 mmHg
Maximum stimulation of the CNS ischemic response occurs when the MAP is
15 - 20 mmHg
What is the stimulus for the Cushing reaction
INCREASED CSF PRESSURE
Briefly describe how the Cushing reaction works
INCREASED CSF PRESSURE COMPRESSES CEREBRAL BLOOD VESSELS. THE REACTION INCREASES ARTERIAL BLOOD PRESSURE TO A LEVEL GREATER THAN CSF PRESSURE. THIS INCREASES CEREBRAL BLOOD FLOW
Decreased blood volume and decreased blood pressure caused by a hemorrhage results in movement of interstitial fluid into systemic capillaries. What is the name of this process?
CAPILLARY FLUID SHIFT
In a normal, healthy heart, the rate of blood flow to the heart equals the rate of blood flow from the heart according to which physiologic law?
THE FRANK-STARLING LAW OF THE HEART
What is the upper limit of CO in a healthy adult
List 4 individual factors that affect CO:
AGE BODY SIZE (BSA) ACTIVITY LEVEL BASAL METABOLIC RATE (BMR)
Name 2 hemodynamic factors that affect CO, that rely on normal heart AND vascular system function
PRELOAD AND AFTERLOAD
What is the cardiac index (CI)?
IT REFLECTS THE CARDIAC OUTPUT FOR INDIVIDUALS BASED ON BODY SIZE AND WEIGHT
What is the average range for the cardiac index
2.5 - 4.0 L/MIN/M2
Why is the cardiac index lower for older persons compared to younger persons?
OLDER PEOPLE ARE LESS ACTIVE
Normally, cardiac output varies inversely with:
SYSTEMIC VASCULAR RESISTANCE
How does increased systemic vascular resistance affect CO?
When an individual exercises, the autonomic nervous system sends signals to the heart and vascular system preventing an abnormal drop in blood pressure when peripheral blood vessels dilate to send more oxygenated blood to exercising tissues. This insures adequate blood flow through capillary beds and adequate VR. List the three (3) major changes in heart and vascular function that occur:
LARGE VEINS CONSTRICT HEART RATE INCREASES MYOCARDIAL CONTRACTILITY INCREASES
Anticipation of exercise stimulates cardioaccelerator function. Briefly describe changes in heart function at this time
HEART RATE INCREASES (PARASYMPATHETIC INPUT TO THE SA NODE, AV NODE, AND ATRIAL MYOCARDIUM IS OVERRIDDEN)
What increases the myocardial contraction force (DURING EXERCISE)
SNS STIMULATION AND CATECHOLAMINE RELEASE
Increased heart rate and increased myocardial contractility have what effect on arterial blood pressure (DURING EXERCISE)
Blood flow to skeletal muscles initially decreases, then increases as tissue O2 consumption increases. What occurs in tissue blood vessels that causes this change in tissue blood flow?
LOCAL CONTROL MECHANISMS (RELEASE OF ENDOGENOUS VASODILATOR SUBSTANCES) ARE ACTIVATED WHEN TISSUE PO2 DECREASES
How is blood flow to the GI tract and kidneys affected? Where is this blood volume going (during exercise)
BLOOD FLOW TO THE GI TRACT AND KIDNEYS IS REDUCED. THIS BLOOD VOLUME IS TRANSLOCATED TO THE VESSELS WITHIN TISSUE THAT HAS A GREATER O2 AND NUTRIENT DEMAND.
Decreased renal blood flow has what effect on GFR? Why is this important? (during exercise)
GFR DECREASES AND URINE OUTPUT IS REDUCED. THIS SERVES TO KEEP FLUID VOLUME IN THE INTRAVASCULAR SPACE
All dilated blood vessels in the skeletal muscles are routing increased blood volume to the venous circulation. What must occur in the systemic veins to insure that VR is keeping pace with CO (during exercise)
How is CVP affected at this point of exercise when dilated blood vessels in skeletal muscle are routing increased blood volume to the venous circulation causing veins to constrict to insure VR is keeping pace with CO