H. Physiology, Ch. 14 - Cardiac Output, Blood Flow, & Blood Pressure (Combo)

Intrinsic regulation of blood flow

"Built-in" mechanisms within individual organs that provide a localized regulation of vascular resistance and blood flow.

In adults, hypertension is generally blood pressure greater than ____

130/90

Higher compliance in veins

A given amount of pressure will cause more expansion in veins than in arteries, so the veins can hold more blood.

Atrial natriuretic peptide (ANP)

A hormone produced by the atria of the heart is antagonistic to aldosterone and promotes Na+ and water excretion in the urine.

The renin-angiotensin-aldosterone system

A hormone system that regulates blood pressure and water (fluid) balance.

Arteriovenous anastomoses

A small blood vessel with a relatively thick muscular coat that provides a direct connection between an artery and vein, thus bypassing capillaries. (termoregulation)

Aldosterone

A steroid hormone secreted by the adrenal cortex, stimulates the reabsorption of salt by the kidneys.

Preeclampsia

A toxemia of late pregnancy characterized by high blood pressure, proteinuria and edema.

Hormone secreted in response to lowered blood volume

ADH

Active hyperemia

An increase in blood flow in sceletal muscles and other organs as a result of increased metabolism.

Atrial stretch receptors

An increase in heart rate due to an increase in central venous pressure. Increased blood volume is detected by stretch receptors located in both atria.

ADH

Antidiuretic hormone involved in the regulation of blood volume.

hormone secreted when blood vol is too high

Atrial natriuretic factor

Total blood volume

Averages about 5.5 L.

Resistance vessels (arteries)

Because muscular arteries and arterioles expand less under the pressure.

Capacitance vessels (veins)

Because veins hold about two-thirds of the total blood volume.

3 important variable affesting blood pressure

Cardiac rate, stroke rate (determined by blood volume), total peripheral resistance. Increase in any of this if not compensated will result in an increased blood pressure.

Extrinsic Control of contractility

Depends on the activity of the sympathoadrenal system. Norepinephrine and epinephrine produce an increase in contraction strength.

Pulse pressure

Equals to systolic pressure minus diastolic pressure.

Edema

Excessive accumulation of interstitial fluid.

Primary (essential) hypertension

Hypertension as a result of complex and poorly understood processes.

Secondary hypertension

Hypertension as a result of known disease processes.

Vasomotor control center

In medulla. Regulates the degree of vasoconstriction/vasodilation and helps to regulate total peripheral resistance.

Auscultatory method of blood pressure measurement

Is based on the correlation of blood pressure and arterial sounds.

Blood flow

Is directly proportional to the pressure difference between the two ends of the tube, but is inversely proportional to the frictional resistance to blood flow through the vessels.

Intrinsic control of contractility

Is due to variations in the degree to which the myocardium is stretched by the end-diastolic volume.

Baroreceptor reflex

It provides a negative feedback loop in which an elevated blood pressure reflexively causes heart rate and thus blood pressure to decrease; similarly, decreased blood pressure depresses the baroreflex, causing heart rate and thus blood pressure to rise.

Hypertension may be treated by ingesting which ions in diet?

K+; Ca2+

Too much plasma __ decreases resting membrane potential of cardiocytes and low blood ___ makes contraction inefficient. Heart stops in what phase

K+; Ca2+; diastole

Too little plasma ___ and too much Ca2+ arrests heart in _____

K+; systole

Cardiac control center

Located in medulla regulates the cardiac rate.

Cardiac control center

Located in the medulla oblongata coordinates the activity of the autonomic innervation of the heart.

Baroreceptors

Located mainly in carotid sinuses and the aortic arch, monitor changes in blood pressure.

Paracrine regulators

Molecules produced by one tissue that help to regulate another tissue of the same organ (tunica interna causes tunica media to relax or contract).

Digitalis is used to treat CHF. Inhibits ____, elevating intracelluar ___. This stimulates ____ exchanger, which increases cardiac ____ concentration and improves strength of contraction.

Na+/K+ ATPase; Na+; Na+/Ca2+; Ca2+

Osmoreceptors

Neurons in the hypothalamus that detect an increase in plasma osmolality (due to dehydration or excessive salt intake), which results in release of ADH.

Laminar flow

Occurs when all parts of a fluid move in the same direction, parallel to the axis of the vessel.

Congestive heart failure

Occurs when the cardiac output is insufficient to maintain the blood flow required by the body.

Circulatory shock

Occurs when there is inadequate blood flow and/or oxygen utilization by the tissues.

Myogenic regulation

Occurs when there is variation in systemic arterial pressure. Blood pressue falls - cerebral arteries dilate, rises - they constrict.

Starling forces

Opposing forces that affect the distribution of fluid across the capillary.

Parasympathetic control of blood flow

Parasympathetic endings in arterioles are always cholinergic and always promote vasodialation, but it is limited to digestive tract, external genitalia and salivary glands.

Bradykinin

Polypeptide that stimulates vasodilation.

Anaphylactic shock

Rapid fall of blood pressure as a result of a severe allergic reaction (bee stings, penicillin).

Septic shock

Refers to a dangerously low blood pressure that may result from sepsis, or infection.

Hypovolemic shock

Refers to circulatory shock that is due to low blood volume (hemorrhage, dehydration, burns).

Regulation of stroke volume

Regulated by 3 variables: 1. end-diastolic volume, 2. total peripheral resistance, 3. contractility.

Mean arterial pressure

Represents the average arterial pressure during the cardiac cycle.

Venous return

Return of blood to the heart via veins.

Turbulent flow

Some parts of the fluid move in different directions, churning and mixing the blood.

Regulation by sympathetic nerves

Stimulation of the sympathoadrenal system produces an increase in the cardiac output and an increase in total peripheral resistance, producing vasoconstriction.

Contractility

Strength of ventricular contraction.

Baroreceptors

Stretch receptors located in the aortic arch and in the carotid sinuses.

Autoregulation

The ability of organs (brain, kidneys) to utilize the intrinsic mechanisms to maintain relatively constant blood flow despite wide fluctuations in blood pressure.

Mean arterial pressure (MAP)

The average pressure. It is about 100mmHg.

Oncotic pressure

The difference between colloid osmotic pressures of blood plasma and interstitial fluid, which is much higher in plasma.

Total peripheral resistance

The frictional resistance, or impedance to blood flow, in the arteries. Stroke volume is inversely proportional to TPR.

Metabolic regulation

The most avtive regions of the brain receive an increased blood flow.

Colloid osmotic pressure

The osmotic pressure exerted by plasma proteins.

Total peripheral resistance

The sum of all the vascular resistances within the systemic circulation.

Reactive hyperemia

The transient increase in organ blood flow that occurs following a constriction. The accumulated metabolic products cause vasodilation.

End-diastolic volume (preload)

The volume of blood in the ventricles at the end of diastole. Stroke volume is directly proportional to EDV.

Cardiac output

The volume of blood pumped per minute by each ventricle. Cardiac output (ml/min) = Stroke volume (ml/beat) x cardiac rate (beats/min).

Stroke volume

Volume of blood pumped per beat by each ventricle - about 70-80 ml per beat.

Frank-Starling law of the heart

Volume of the heart increases in response to an increase in the volume of blood filling the heart (the end diastolic volume). The increased volume of blood stretches the ventricular wall, causing cardiac muscle to contract more forcefully (the so-called Frank-Starling mechanisms).

Extrinsic control of coronary blood flow includes sympathetic and adrenal control. ___ (alpha/beta) adrenergic receptors promote vasoconstriction and ___ adrenergics promotes vasodilation

alpha; beta

Low blood pressure as result of severe allergic reaction. Widespread release of histamine, which is a vasodilator

anaphylactic shock

For the heart to eject blood, the pressure in ventricle must be greater than the ____ pressure, which is a function of the peripheral resistance of the vessels.

arterial

Cerebral autoregulation may involve ____ transmitting metabolic information to endothelial cells.

astrocytes

Atrial stretch receptors are located in ____. They are activated by an increase in ____ _____. They stimulate reflex tachycardia through increased sympathetic nerve activity. They inhibit ___ release causing larger urine volume and decline in blood volume. They also increase ___ secretion.

atria of heart; venous return; ADH;ANF

The medulla oblongata of the brain stem coordinates ____ effects on the heart.

autonomic

Extrinsic regulation of blood flow is controlled by the ____ and ____ systems

autonomic; endocrine

The driving force of filtration is the ___ ____ in the capillaries, which is higher than ____ ____ in the interstitial fluid.

blood pressure; hydrostatic pressure

Veins are ____ vessels, while arteries are ____ vessels.

capacitance; resistance

Increased blood pressure or venous obstruction increases ___ ___ pressure so that fluid moves into tissues

capillary filtration

Volume of blood pumped per min by each ventricle

cardiac output

Vasodilation in one large organ may decrease total peripheral resistance, but this is normally prevented by increase in ___ ____ and vaso ____ in other areas.

cardiac output; constriction

arterial blood pressure is proportional to ___ ___ multiplied by ___ ___ ___

cardiac output; total peripheral resistance

Parasympathetic innervation of arterioles is always _____ (cholinergic/adrenergic) and always causes vaso_____(dilation/constriction)

cholinergic; dilation

Osmotic pressure exerted by plasma proteins

colloid osmotic pressure

The sympathoadrenal system raises blood pressure by vaso____, thus raising total peripheral resistance, which increases ___ ____.

constriction; cardiac output

Cardiac rate increases during exercise due to ____ (increased/decreased) vagal inhibition of the SA node.

decreased

Cerebral autoregulation likely involves a CO2 sensor. A rise in brain CO2 causes vaso____(dilation/constriction)

dilation

Intrinsic control of coronary blood flow involves vaso____(dilation/constriction) during exercise. Metabolism of myocardium increases and there is a local accumulation of ___, ___ and adenosine and lack of ___, which all promote cardiac muscle relaxation.

dilation; CO2; K+; O

Frank-Starlin Law of the heart implies that the strength of contraction is intrinsically adjusted by ___ ___ ___

end diastolic volume

Stroke volume is dependent on 3 variables: 1. __ ___ volume 2. total ____ resistance (frictional resistance, impedance to flow from arteries_ 3. ____ (strength of ventricular contraction_

end diastolic; peripheral; contractility

NO, bradykinin, and PGI2 are ____-derived relaxing factors

endothelium

The longer/skinnier a rube is, the ____ (greater/lesser) the resistance.

greater

colloid osmotic pressure of the plasma is ___ (greater/less than) that of interstitial fluid

greater

Shock caused by low blood volume, involves decrease blood pressure and cardiac output

hypovolemic shock

Cardiac rate

in adults about 70 beats per minute.

Baroreceptors are the pressure sensors in the aorta and carotid arteries. A fall in blood pressure produces ____ (increase/decrease) in heart rate.

increase

an increase in end diastolic volume causes an ____ (increase/decrease) in stroke volume

increase

In congestive heart failure, the body tries to compensate by activating sympathoadrenal axis to ____ cardiac rate and induce vaso_____. Elevated blood ____ and dilation/hypertrophy of _____.

increase; constriction; volume; ventricles.

ACh _____ (increases/decreases) pacemaker potential. It promotes opening of K+ channels and hyperpolarizes pacemaker cells.

increases

2/3 of the body's water is within cells. Of the remaining 1/3 extracellular water, 80% is in ____ fluid and 20% is in ___.

interstitial; blood (plasma)

ADH causes kidneys to secretes ___ (more/less) water in urine

less

Intrinsic regulation of blood flow is controlled by ____ factors

metabolic

As EDV rises, the ___ is stretched and contraction of the heart is more forceful. Stretching of the ventricle positions actin and myosin filaments at optimum distance, thus increasing force of heart muscle contraction.

myocardium

Stroke volume is ___ (pos/neg) correlated to peripheral resistance, but this can be accommodated within minutes.

neg

Blood volume (urine/tissue fluid volume) is ____ (negatively/positively) correlated to cardiac output

negatively

Starling forces are the opposing forces of ___ pressure and ____ ____ pressure that affect distribution of fluid across capillary

osmotic; hydrostatic filtration

At arteriole end of capillary, fluid moves ___ (out/into) capillary At venule end of capillary, fluid moves ___ (out/into) capillary

out of; into

Intrinsic regulation (autoregulation) of blood flow involves products of metabolism: decreased ____ consumption, increased ____, decreased ___, and release of adenosine or __.

oxygen; CO2; pH; K+

Norepineprine and epinephrine increase cardiac rate by shortening the ____ potential, so it takes less time for pacemaker to reach threshold.

pacemaker

The vagus nerve provides main ____ (sympathetic/parasympathetic) input to the heart.

parasympathetic

In hypertension, organ damage could occur due to high ___ pressure. There may also be thickening of vessel walls, vascular damage, atherosclerosis. Also increase in _____ (preload/afterload) which makes the left ventricle work harder. Cerebral vasculature damage may cause ____

perfusion; afterload; stroke

In essential hypertension, increased ___ ___ is characteristic. Cardiac rate and cardiac output are ____ (higher/lower) in general. This could be caused by defect in ______ system, high ___ intake combined with metabolic defect, sustained high ___, and genetics.

peripheral resistance; higher; renin-angiotensin; salt; stress

Resistance in our blood vessels correlates to total ____ resistance and mean ___ pressure.

peripheral; arterial

Stroke volume is __(pos/neg) correlated to contractility.

pos

Negative intrathoracic pressure is ___(pos/neg) correlated to cardiac output.

positively

Venous pressure (venoconstriction/skeletal muscle pump) is _____ (pos/neg) correlated to cardiac output.

positively

Amount of blood in the ventricles when AV and semilunar valves are shut, the ventricles are filled, just prior to contraction

preload

Extrinsic regulation

refers to control by the autonomic nervous system and endocrine system. (hormones producing vasoconstriction)

Aldosterone is secreted when ___ content is too low.

salt

Low blood pressure resulting from sepsis or infection. caused by endotoxin, could be due to NOS activaion in macrophages

septic shock

In paracrine regulation of blood flow, endothelium releases factors which relax ___ ____ of arterioles.

smooth muscle

vol of blood pumped per beat by each ventricle

stroke volume

cardiac output = ___ volume x ____ rate

stroke; cardiac

In congestive heart failure, failure of right ventricle raises pressure in right atrium, causing congestion in ____ circulation.

systemic

Resting bradycardia of athletes is due to high ___ activity.

vagal

In congestive heart failure, failure of left _____ (atrium/ventricle) raises pressure in the left ____, producting pulmonary congestion and edema, resulting in shortness of breath and fatigue.

ventricle; atrium

Edema is the accumulation of ____ in interstitial fluid

water