Physiology III - Exam 2 (Part 2)

What is the expansion and recoil of an artery during heart activity?

Pulse

What is stroke volume x heart rate?

Cardiac output

What hinges on three variables: blood viscosity, vessel length, and vessel radius?

Peripheral resistance

What is the event primarily responsible for peripheral resistance?

Contraction of arterioles

Where are sites where blood pressure readings are made (normally)?

Over arteries

Where are points on the body where pulse may be felt?

Pressure Points

What are the sounds heard over a blood vessel when the vessel is partially compressed?

Sounds of Korotkoff

What is the force that blood exerts against a vessel wall? Where is it measured?

Blood pressure

-- measured at brachial artery of arm using sphygmomanometer

What is a normal blood pressure reading?

120/80

What is the peak arterial BP taken during ventricular contraction (ventricular systole)? What is this telling us?

Systolic Pressure

-- reflects the arterial pressure resulting form the ejection of blood during ventricular contraction (systole)

NOTE: this is the first number (ex: 120/80 its the 120)

What is the minimum arterial BP taken during ventricular relaxation between heart beats? What is this telling us?

Diastolic pressure

-- represents arterial pressure of blood during ventricular relaxation (diastole)

NOTE: this is the second number (ex: 120/80 its the 80)

What is the difference between systolic and diastolic pressure? What is significant about this/what does it tell us?

Pulse Pressure

-- measure of driving force on circulation and stress exerted on small arteries by pressure surges generated by the heart

(ex: 120/80 would be 120-80 = 40 mmHg)

NOTE: if number high, means overall circulatory system pressure HIGH

What is the mean pressure one would obtain by taking measurements at several intervals throughout the cardiac cycle and is the average blood pressure that most influences risk level for edema, fainting (syncope) atherosclerosis, kidney failure, and aneurysm? What is the calculation for it?

Mean arterial pressure (MAP)

Diastolic pressure + 1/3 pulse pressure

(ex: 120/80 --> 80 + (1/3)(120-80) )

NOTE: helps us indicate overall organ supply and pressure to sustain organ supply

What is the ideal range for MAP?

70-110

How is blood flow different between arteries and veins?

Arteries = pulsatile; surging fast; spurts form open artery

Veins/Capillaries = slow & stead (even with bleeding)

What are two reasons why BP tends to rise with age?

Arteriosclerosis & Atherosclerosis

What is the buildup of lipid deposits that become plaques?

Atherosclerosis

What is the stiffening of arteries due to deterioration of elastic tissue of artery walls?

Arteriosclerosis

What is high blood pressure called? Low blood pressure? What 3 things can cause a low blood pressure state?

High BP = Hypertension (>140/90)

Low BP = Hypotension

--> caused by blood loss, dehydration, anemia (decreased RBC concentration)

What is it called when systolic blood pressure is higher than 130, but diastolic blood pressure is under 80 (still normal)?

Isolated systolic hypertension

What are some ways that isolated systolic hypertension is treated?

- BP drugs

- Diuretics to help kidneys flush water and sodium from body

- Beta-blocker making heart beat slower/less forceful

- Angiotensin-converting enzyme (ACE) inhibits AT2 or calcium channel blockers to relax blood vessels

-Renin inhibitors to keep kidneys form making chenmical that can lead to higher blood pressure

- Stop smoking

- Lower salt in diet

- Cut back alcohol

- Get to/stay at healthy weight

- Exercise regularly

What is the most common cardiovascular disease affecting about 30% of Americans over 50

Hypertension

Why is Hypertension the "silent killer"?

Major cause of heart failure, stroke, and kidney failure (often not really symptomatic until damage has occured)

-- Damages heart by increasing afterload (myocardium enlarges until overstretched and inefficient)

-- Renal arterioles thicken in response to stress (drop in renal BP leads to salt retention and worsens overal hypertension)

What type of hypertension makes up 90% of cases due to obesity, sedentary behavior, diet, or nicotine?

Primary hypertension

What type of hypertension makes up 10% of cases due to a kidney disease, atherosclerosis, hyperthyroidism, or Cushing syndrome?

Secondary Hypertension

(underlying condition causing the BP)

Blood pressure is determined by what three things?

1) Cardiac output (HR x SV)

2) Blood volume

3) Resistance to flow

What organ mainly regulates blood volume?

Kidneys

What is the amount of blood glowing through an organ, tissue, or blood vessel in a given time (mL/min)?

Blood flow

(for given period of time)

What is the flow per given volume or mass of tissue in a given time (mL/min/g)

Perfusion

(discussing organ itself)

Blood supply to a tissue can be expressed in terms of ____ & ______?

Flow and perfusion

At rest, total flow is quite constant and equal to what other measure?

Cardiac output (HR x SV)

-- averages 5.25 L/min

Does the kidney or liver receive more BLOOD FLOW? Does the kidney or liver have a greater PERFUSION?

Flow = Liver more than kidney

-- because its large supply and more whole supply

Perfusion = Kidney more than liver

-- because of its more vascular density and more blood supply per 100 g of tissue

Blood pressure, resistance, and flow is important for the delivery of ______ and removal of ______?

Delivery of nutrients/oxygen

Removal of metabolic wastes

What is the flow of blood through blood vessels?

Hemodynamics

What is the distance that a particle of fluid travels with regard to time?

Velocity

What is the rate of displacement of a volume of fluid?

Flow

What is the relationship between flow, pressure, and resistance?

F = P / R

-- greater pressure difference between two points, the greater the flow

-- greater resistance, less flow

(change in pressure proportional to flow; resistance is inversely proportional to flow)

What is the study (non-pulsatile) laminar flow of Newtonian fluids through rigid cylindrical tubes, where the flow through a tube increases as the pressure gradient is increased, and it decreases as either viscosity of the fluid or length of the tube increases?

Poiseuille's Law

What three variables determine peripheral resistance? Which is the most powerful influence on flow>

1) Blood viscosity

2) Vessel length

3) Vessel radius --> MOST POWERFUL INFLUENCE

When it comes to the effect of blood viscosity on peripheral resistance, concentrations of what substances elevate viscosity the most?

RBC count & Albumin concentration

________ viscosity with anemia and hypoproteinemia will ______ flow.

DECREASED viscosity

SPEED flow

_______ viscosity with polycythemia and dehydration will ______ flow

INCREASED viscosity

SLOW flow

When it comes to the effect of vessel length on peripheral resistance, the farther the blood travels through a tube, the more cumulative friction it encounters, therefore having what affect on pressure and flow?

More distance = DECREASED pressure & flow

What are the two vasoreflexes involved in changing vessel radius?

1) Vasoconstriction --> when smooth muscle of tunica media contracts

2) Vasodilation --> relax smooth muscle, allowing blood pressure to expand vessel

What is the flow in layers, where flow is faster in the center?

Laminar flow

T/F: Vessel length is the ONLY significant way of controlling resistance.

FALSE

Vessel radius is the ONLY

T/F: Blood viscosity markedly affects blood velocity.

FALSE

Vessel radius markedly affects blood viscosity

Blood flow is proportional to the 4th power of radius... What does this mean?

If the vessel diameter decreases by half, the resistance will increase by 16x

From aorta to capillaries, blood velocity (speed) decreases for what three reasons?

1) Greater distance (more friction/reduced speed)

2) Smaller radii of arterioles and capillaries have MORE resistance

3) Further form heart, number of vessels and their cross-sectional area become greater and greater

Why does velocity increase from capillaries to vena cava? How does this compare to the flow this same blood had in the arteries?

Veins larger so they create less resistance than capillaries

- Blood in veins never regain velocity it had in arteries as they are further from pumping heart and more compliant (stretch more)

What is the most significant point of control over peripheral resistance and flow, producing HALF of the total peripheral resistance?

Arterioles

-- on proximal side of capillary bed and best positioned to regulate flow; outnumber any other artery type; more muscular in proportion to their diameter; & highly capable of changing radius

What are the three ways of controlling vasomotor activity??

1) Local control

2) Neural control

3) Hormonal control

What are the four ways in which local control will regulate blood pressure?

1) Autoregulation

2) Vasoactive chemicals

3) Reactive hyperemia

4) Angiogenesis

In vasomotor local control, what is the ability of tissues to regulate their own blood supply?

Autoregulation of blood flow

What is the metabolic theory of autoregulation?

If tissue is inadequately profuse, waste accumulates which stimulates vasodilation (and increases perfusion)

How does the body autoregulate the blood flow in local control? (2)

1) Bloodstream delivers oxygen and removes metabolites

2) When wastes are removed, vessels constrict

What is the response to increased tissue metabolic activity?

Active Hyperemia

In vasomotor local control, what are the substances secreted by platelets, endothelial cells, and perivascular tissue to stimulate vasomotor responses?

Vasoactive chemicals

Histamine, bradykinin, and prostaglandins are vasoactive chemicals that sitmulate what?

Vasodilation

Endothelial cells secrete vasoactive chemicals such as prostacyclin and nitric oxide which stimulate what?

Vasodilation

Vasoactive chemicals like Endothelin 1, Angiotensin II, and Thromboxane A2 stimulate what?

Vasoconstriction

In vasomotor local control, what occurs if the blood supply cut off is then restored, so blood flow increases above normal (as a response to the occlusion)?

Reactive hyperemia

In vasomotor local control, what is the growth of new blood vessels that occurs in regrowth of uterine lining, around the coronary artery in obstructions, in exercised muscle, and in malignant tumors?

Angiogenesis

T/F: Angiogenesis is controlled by several growth factors and inhibitors

TRUE

What route of vasomotor control is where the central and autonomic (sympathetic) nervous systems exert control over blood vessel size and integrates centers for the three autonomic reflexes: baroreflexes, chemoreflexes, and medullary ischemic reflex?

Neural Control

In vasomotor neural control, what is the automatic negative feedback response to a change in blood pressure?

Baroreflexes

When there is a ________________ in blood pressure, it is detected by the carotid sinuses, and ___________ nerve sends the signals to the brain stem?

INCREASE

glossopharyngeal nerve

The signal sent to the brainstem about the BP will result in what two things to happen?

1) Inhibits sympathetic cardiac & vasomotor neurons

2) Excites vagal fibers that slow heart rate

T/F: Baroreflexes govern long-term regulation of blood pressure.

FALSE

- short term

-- adjusts for rapid changes in posture, but NOT helpful for correcting chronic hypertension

In vasomotor neural control, what is the automatic response to changes in the blood chemistry (especially pH, O2, & CO2)? What is the receptor for this and where is it located?

Chemoreflexes

Receptor = aortic bodies & carotid bodies

-- located in aortic arch and bifurcation of common carotid

What is the primary role of Chemoreflexes? Secondary role?

Primary = Adjust respiration to change blood chemistry

Secondary = Vasomotion

-- widespread vasoconstriction, increasing BP, increasing lung perfusion and gas exchange, and stimulating breathing

In vasomotor neural control, what is the automatic response to a drop in perfusion of the brain?

Medullary ischemic reflex

T/F: The medulla oblongata monitors its own blood supply and activates corrective reflexes when it senses ischemia (insufficient perfusion).

TRUE

When the medulla oblongata senses the ischemia, cardiac and vasomotor centers send sympathetic signals to the heart and blood vessels to do what 3 things?

1) Increase heart rate and contraction force

2) Cause widespread vasoconstriction

3) Raise BP and restore normal perfusion to brain

T/F: The vasomotor center is independent of other brain centers when it comes to blood pressure.

FALSE

-- other brain centers can affect vasomotor center

(ex: stress, anger, and arousal can increase blood pressure)

What regulation of blood pressure through vasomotor activity is where hormones influence the blood pressure, some through their vasoactive effects, and some by regulating water balance?

Hormonal control

In vasomotor hormonal control, what hormone is a potent VASOCONSTRICTOR because it RAISES blood pressure, promotes Na and water retention by kidneys, and increases blood volume & pressure?

Angiotensin II

In vasomotor hormonal control, what hormone increases urinary sodium excretion, therefore reducing blood volume, promoting VASODILATION, and LOWERING blood pressure?

Atrial natriuretic peptide (ANP)

In vasomotor hormonal control, what hormone promotes water retention and RAISES blood pressure, and at pathologically high concentrations, is a VASOCONSTRICTOR?

ADH (antidiuretic hormone)

In vasomotor hormonal control, what hormone is a VASOCONSTRICTOR in most blood vessels as it binds to alpha-adrenergic receptors, but in cardiac muscle is a VASODILATOR as it binds beta-adrenergic receptors?

Epinephrine & Norepinephrine

What are the two purposes of Vasoreflexes (dilation & constriction)?

1) General control of BP

2) Routing blood from one body region to another

Does an increased diameter of the arterioles have a increasing or decreasing effect on blood pressure?

Decrease

Does increased blood viscosity have a increasing or decreasing effect on blood pressure?

Increased

Does increased cardiac output have a increasing or decreasing effect on blood pressure?

Increased

Does increased pulse rate have a increasing or decreasing effect on blood pressure?

Increased

Does anxiety/fear have a increasing or decreasing effect on blood pressure?

Increased

Does increased urine output have a increasing or decreasing effect on blood pressure?

Decreased

Does a sudden change in position from reclining to standing have a increasing or decreasing effect on blood pressure?

Decreased

Does physical exercise have a increasing or decreasing effect on blood pressure?

Increased

Does alcohol have a increasing or decreasing effect on blood pressure?

Decreased

Does hemorrhage have a increasing or decreasing effect on blood pressure?

Decreased

Does nicotine have a increasing or decreasing effect on blood pressure?

Increased

Does Arteriosclerosis have a increasing or decreasing effect on blood pressure?

Increased

Does stimulation of arterial baroreceptors have a increasing or decreasing effect on blood pressure?

Decreased

Does stimulation of carotid body chemoreceptors have a increasing or decreasing effect on blood pressure?

Increased

Does release of epinephrine form adrenal medulla have a increasing or decreasing effect on blood pressure?

Increased

Does secretion of ADH have a increasing or decreasing effect on blood pressure?

Increased

T/F: Renin, released by the kidney, causes a decrease in blood pressure

FALSE

- increase

T/F: Two body organs in which vasoconstriction rarely occur are the heart and kidneys

FALSE

- heart & brain

T/F: In active skeletal muscle, autoregulated vasodilation is promoted by an increase in carbon dioxide in the area

TRUE