Hemodynamics and Flow Patterns

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Questions and Answers

What is the main function of baroreceptors in the cardiovascular system?

To increase heart rate during exercise

To regulate blood pressure by opposing fluctuations (correct)

To decrease blood volume during hemorrhage

To enhance myocardial contractility

What triggers the CNS ischemic response?

Increased blood pressure above 100 mm Hg

Rapid decrease in heart rate

Diminished blood flow to the brain (correct)

Increased venous return to the heart

What mechanism does the body use for long-term blood pressure regulation?

Baroreceptor adaptation to new blood pressure levels (correct)

Epinephrine release from adrenal glands

Changes in vascular resistance only

Increase in heart rate through sympathetic activation

What is orthostatic hypotension characterized by?

Decrease in arterial pressure upon standing Signup and view all the answers

Which baroreceptor has a lower limit of response?

Carotid baroreceptor at approximately 60 mm Hg Signup and view all the answers

What occurs during the body's response to hemorrhage?

Activation of sympathetic vasoconstriction to maintain circulation Signup and view all the answers

What is the role of the vasomotor center during a CNS ischemic response?

Induce vasoconstriction in peripheral vessels Signup and view all the answers

What is a primary advantage of using normal saline in hemodynamic measurements?

Saline is completely innocuous Signup and view all the answers

What is a common consequence of baroreceptor adaptation after prolonged high blood pressure?

Decreased ability to regulate blood pressure Signup and view all the answers

According to Poiseuille's Law, which factors primarily determine blood flow?

Pressure difference and radius Signup and view all the answers

What is one clinical consequence of turbulent flow in blood vessels?

Damage to platelets leading to clot formation Signup and view all the answers

What measure is used to calculate resistance to flow according to Poiseuille's Law?

Pressure difference divided by flow Signup and view all the answers

How does a decrease in blood vessel diameter affect flow?

It potentially increases turbulence and reduces flow efficiency Signup and view all the answers

What condition is primarily indicated by increased capillary pressure due to venous obstruction?

Blood clots Signup and view all the answers

Which condition could lead to increased turbulence in blood flow?

Increased blood flow velocity from exercise Signup and view all the answers

What effect does anemia have on blood flow in relation to turbulence?

Decreases viscosity, potentially increasing turbulence Signup and view all the answers

Which of the following is NOT a cause of decreased plasma proteins?

Severe dehydration Signup and view all the answers

What risk is associated with the procedure of injecting normal saline into the right atrium?

Risk of pneumothorax and valve damage Signup and view all the answers

What mechanism helps facilitate venous return through the contraction of leg muscles?

Venous pump or muscle pump Signup and view all the answers

Which factor contributes to increased capillary permeability?

Histamine release during allergic reactions Signup and view all the answers

What is the typical range for central venous pressure (CVP)?

2-6 mm Hg Signup and view all the answers

Which of the following describes the hydrostatic pressure in veins while a person is standing erect?

90 mm Hg at ankles Signup and view all the answers

What role does the abdomino-thoracic pumping mechanism play in venous return?

Squeezes veins in the abdomen Signup and view all the answers

What condition is indicated by increased venous pressure in the extremities when a person is standing still?

Venous obstruction Signup and view all the answers

What does compliance measure in blood vessels?

Ability to expand in response to internal pressure Signup and view all the answers

As the aorta ages, what change in compliance is typically observed?

It becomes less compliant Signup and view all the answers

Which factors primarily influence pulse pressure?

Stroke volume and compliance Signup and view all the answers

Which equation accurately describes Mean Arterial Pressure (MAP)?

MAP = DBP + (SBP - DBP) × 3 Signup and view all the answers

What role does microcirculation primarily serve?

Facilitates gas exchange and waste removal Signup and view all the answers

What primarily contributes to controlling blood flow in microcirculation?

Local tissue metabolic needs Signup and view all the answers

Which factors are known to affect blood pressure?

Age, gender, and diet Signup and view all the answers

Acute control in the microcirculation occurs within which timeframe?

Seconds to minutes Signup and view all the answers

What primarily causes osmosis of fluid inward through the capillary membrane?

Plasma colloid osmotic pressure Signup and view all the answers

Which factor does NOT typically influence the rate of diffusion?

Hydrostatic pressure difference Signup and view all the answers

What is the role of plasma proteins in the context of osmotic pressure?

They exert osmotic pressure that retains fluid in the capillaries. Signup and view all the answers

What occurs when there is elevated capillary pressure?

Increased filtration of fluid from capillaries Signup and view all the answers

Which of the following substances primarily determines the permeability of capillaries?

Molecular size Signup and view all the answers

What is the primary function of the lymphatic system?

Return interstitial fluid to the blood Signup and view all the answers

What condition results from abnormal capillary dynamics leading to excess interstitial fluid?

Edema Signup and view all the answers

Which factor does NOT increase lymph flow rate?

Increased capillary osmotic pressure Signup and view all the answers

Study Notes

Hemodynamics

Hemodynamics are the physical principles of pressure, flow, resistance, and compliance that relate to the cardiovascular system.
Flow is proportional to the pressure difference between the ends of the tube.
Blood flow is most affected by pressure difference and radius of the blood vessel.
Blood viscosity is measured by hematocrit.
High hematocrit = higher friction.
Resistance depends on the diameter of the blood vessels.

Streamlined vs Turbulent Flow

Streamlined flow is orderly and silent with low resistance, it is characterized by concentric layers of fluid slipping past each other.
Turbulent flow is chaotic and disorganized, cross-currents form.
Turbulent flow can damage platelets and cause blood clots.
Turbulent flow can be caused by constricted blood vessels, a narrowing of a heart valve, increased flow rate (pregnancy, hyperthyroidism), or decreased viscosity (anemia).

Factors Affecting Turbulence

High flow velocity.
Vascular resistance.

Arterial System

The arterial system converts intermittent flow generated by the heart to a virtual steady flow through the capillaries.
Compliance is the ability of vessels to expand in proportion to pressure.
Compliance decreases with age.
Veins have a greater volume capacity than arteries.

Systolic and Diastolic Pressures

The pressure in the arterial system rises and falls with each beat of the heart.
Pulse pressure is the difference between systolic and diastolic pressures (SBP - DBP).

Mean Arterial Pressure (MAP)

MAP is the average pressure in the arterial system over a single cardiac cycle.
MAP is determined by the volume of blood in the arterial system and is calculated as DBP + (SBP-DBP)/3.

Factors Affecting Blood Pressure

Age
Gender
Diet
Weight
Pregnancy
Behaviors (smoking, alcohol intake, illicit drugs, medications)

Microcirculation

Microcirculation is the network of tiny blood vessels that connect arteries and veins.
They exchange nutrients, water, gases, hormones, and waste products.
Exchanges are accomplished by diffusion and bulk flow.

Local Control of Blood Flow

Flow is controlled in proportion to individual tissue needs.
Greater metabolism = Greater blood flow.

Acute Control of Blood Flow

Occurs through auto-regulation and vasomotion.
Occurs within seconds to minutes.
Decreases in oxygen (decreased [O2] ) make vessels relax and increase blood flow.

Effect of Molecular Size

Permeability of capillaries varies according to molecular diameters, permeability of capillaries differ in different tissues.

Effect of Concentration Difference

The net rate of diffusion is proportional to the concentration difference.

Bulk Flow

Move more water and dissolved substances through membranes than diffusion alone.
It is caused by hydrostatic pressure differences.

Osmotic Pressure Differences

Osmotic pressure is exerted by substances that cannot move through capillary membrane.
Exerted by plasma proteins.

Factors that Determine Fluid Movement

Capillary pressure pushes fluid outward through capillary membranes.
Interstitial fluid pressure makes fluid move outward.
Plasma colloid osmotic pressure moves fluid inward.
Interstitial fluid colloid osmotic pressure moves fluid outward.

Lymphatic System

It is an accessory route used to return fluid from interstitial spaces to the blood.
It also transports proteins and large particulate matter.
It is important in fighting bacterial infections.

Formation of Lymph

Derived from interstitial fluid that flows into the lymphatics.

Determinants of Lymph Flow Rate

Interstitial fluid pressure is affected by elevated capillary pressure, decreased plasma colloid osmotic pressure, increased interstitial fluid proteins, and increased capillary permeability.
The lymphatic pump pushes lymph forward.

Edema

Edema is excess interstitial fluid in the tissues.
Edema is caused by abnormal capillary dynamics.

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Description

This quiz covers the principles of hemodynamics, including the concepts of pressure, flow, and resistance in the cardiovascular system. It also explores the differences between streamlined and turbulent flow, and the factors that influence turbulence. Test your understanding of these essential cardiovascular mechanics.