Control of Blood Flow and Pressure

This set of flashcards covers key concepts related to the quantitative physiology of blood flow and pressure, including heart regulation, blood vessel composition, cardiovascular disease, and related physiological mechanisms.

What is stroke volume (SV)?

The amount of blood pumped by one ventricle during a contraction.

How is stroke volume calculated?

Stroke volume is calculated by subtracting end systolic volume (ESV) from end diastolic volume (EDV).

What is the average stroke volume?

The average stroke volume is approximately 70 mL.

What is cardiac output (CO)?

The volume of blood pumped by one ventricle in a given period of time.

How is cardiac output calculated?

Cardiac output is calculated as heart rate (HR) multiplied by stroke volume (SV).

What is the average cardiac output?

The average cardiac output is about 5 L/min.

Where is heart rate (HR) initiated?

Heart rate is initiated by autorhythmic cells in the SA node.

How does the autonomic division modulate heart rate?

Through neural and hormonal inputs affecting the SA node.

What is the effect of parasympathetic stimulation on heart rate?

Parasympathetic stimulation decreases heart rate.

What neurotransmitter is associated with parasympathetic control?

Acetylcholine (ACh) is the neurotransmitter associated with parasympathetic control.

What are the effects of sympathetic stimulation on heart rate?

Sympathetic stimulation increases heart rate.

What neurotransmitter is involved in sympathetic control of heart rate?

Norepinephrine (NE) is involved in sympathetic control.

What is the role of the cardiovascular control center?

It integrates inputs to regulate heart rate and blood pressure.

How does blood pressure relate to blood flow?

Blood flows from areas of high pressure to areas of low pressure.

What is the equation for blood flow in relation to pressure?

Flow is proportional to the difference in pressure (ΔP) divided by resistance (R).

What is the primary determinant of blood flow?

The primary determinant of flow speed is the cross-sectional area of the vessels.

How does resistance affect blood flow?

Higher resistance decreases blood flow.

What structure in blood vessels regulates its diameter?

Smooth muscle in the blood vessel walls regulates diameter.

What percentage of blood volume is stored in veins?

About 60% of blood volume is stored in veins.

What percentage of blood volume is stored in arteries?

About 11% of blood volume is stored in arteries.

What is angiogenesis?

Angiogenesis is the development of new blood vessels.

Which factors promote angiogenesis?

Cytokines like VEGF and FGF promote angiogenesis.

What is the clinical relevance of angiogenesis?

It is important in tumor growth and coronary heart disease.

What does blood pressure reflect?

It reflects the driving force created by the heart.

What is systolic pressure?

Systolic pressure is the highest pressure in the arteries during ventricular contraction.

What is diastolic pressure?

Diastolic pressure is the lowest pressure in the arteries during ventricular relaxation.

What device is used to measure blood pressure?

A sphygmomanometer is used to measure blood pressure.

What happens when the cuff pressure is higher than systolic pressure?

No sound is heard because arterial blood flow is stopped.

What are Korotkoff sounds?

Sounds created by pulsatile blood flow through a compressed artery.

What is mean arterial pressure (MAP)?

MAP is the average pressure in a person's arteries during one cardiac cycle.

How is MAP calculated?

MAP = diastolic pressure + 1/3(systolic pressure - diastolic pressure).

What happens to baroreceptors when blood pressure increases?

Baroreceptors fire more frequently when blood pressure increases.

What is atherosclerosis?

Atherosclerosis is the buildup of plaque in arteries.

What is one major risk factor for atherosclerosis?

Elevated low-density lipoprotein (LDL) cholesterol is a major risk factor.

What is hypertension?

Hypertension is chronically elevated blood pressure.

What are two controllable risk factors for cardiovascular disease?

Smoking and obesity are controllable risk factors.

What happens to heart function during hypertension?

The heart hypertrophies to maintain blood flow at higher pressures.

What is the function of the lymphatic system?

It returns fluid and proteins to the circulatory system and filters pathogens.

What is edema?

Edema is swelling resulting from disrupted exchange between the circulatory and lymphatic systems.

What can cause tissue hypoxia downstream of a clot?

Insufficient blood flow caused by a clot can lead to tissue hypoxia.

How do capillaries facilitate exchange?

Capillaries have thin walls that allow for efficient exchange of materials.

What are continuous capillaries?

Continuous capillaries have tight junctions between endothelial cells.

What is the effect of high hydrostatic pressure in capillaries?

It causes net filtration of fluid out of the capillaries.

What causes net absorption at the venous end of capillaries?

Higher colloid osmotic pressure causes net absorption.

What is the relationship between capillary density and metabolic activity?

Capillary density correlates with the metabolic activity of nearby cells.

What two factors primarily determine capillary exchange?

Hydrostatic pressure and colloid osmotic pressure primarily determine capillary exchange.

What is the result of increased colloidal pressure in capillaries?

It decreases absorption of fluid into the capillaries.

What does the baroreceptor reflex help regulate?

The baroreceptor reflex helps regulate blood pressure.

Where are carotid baroreceptors located?

Carotid baroreceptors are located in the carotid arteries.

What is a thrombus?

A thrombus is a clot that occludes a blood vessel where it forms.

What is an embolus?

An embolus is a clot that has broken free and travels through the bloodstream.

How can high blood pressure affect the heart and lungs?

It can lead to pulmonary edema and heart failure.

What happens when blood pools in the lower extremities upon standing?

It reduces blood volume in the ventricles, lowering cardiac output.

endothelium?

regulates interaction with blood cells

Smooth muscle?

diameter

elastic connective tissue?

resp to pressure

fibrous connective tissue?

mech strength

What does the capacitor represent?

aorta

What does the Resistor represent?

Resistance to flow due to small arteries.

arteriolar resistance

local control in CNS, based on tissue needs; reflexes = autonomic control; site of variable resistance == blood distribution

arteriolar resistance example

Homeostatic needs: temperature – diverts vessels away or to skin

Brain-gut vessel control after a meal,

A clot is lodged in an arteriole vessel. Downstream of the clot the vessel is becoming hypoxic (↓ O2) and metabolic paracrines are accumulating. What happens next?

The change in paracrines will trigger local vasodilation of the vessel, restoring blood flow

cappillary exchange guarantee two things?

It ensures that all tissues have access to exchange

It allows rapid exchange

Fenestrated capillaries?

Large pores between endothelial cells allow large volumes of fluid to exchange in kidney & intestine

A patient has a disorder that results in insufficient elimination of proteins from the blood plasma. How would this effect capillary exchange?

Increase colloidal pressure; increase absorption

three main fxns of lymphatic system?

Fluid balance, immune response, lipid absorption

Atherosclerosis clot from ruptured plaque can three options:

Resolve, Occlude vessel, break free; heart attack = coronary vessels; stroke = cerebral vessels