Cardiovascular Physiology Flashcards
What are the primary functions of the cardiovascular system?
Transport and distribute essential substances to tissue, removal of byproducts of cellular metabolism.
What is the purpose of arterial wall recoil during diastole?
To help move blood through the circulatory system during relaxation of the heart.
What role do skeletal muscles play in venous return?
Skeletal muscles compress veins, aiding in the return of blood to the heart.
What are the main components of blood?
- plasma
- red blood cells
- white blood cells
- platelets
What is the function of plasma in the blood?
Regulates blood pressure and temperature, contains water, electrolytes, and proteins.
What is the role of red blood cells?
Carry oxygen from the lungs to the tissues and return carbon dioxide from the tissues to the lungs.
What is anemia?
A condition characterized by a lack of red blood cells or hemoglobin, leading to reduced oxygen transport.
What is polycythemia?
A condition with an increased number of red blood cells, leading to thicker blood.
What are leukocytes?
Leukocytes: White blood cells that protect the body against infection.
What is the role of blood platelets?
Involved in blood clotting, prevent abnormal bleeding.
What is the significance of low platelet count?
Leads to increased risk of bruising and abnormal bleeding.
What happens when there is a high number of platelets?
It can lead to thrombosis or blood clots.
What factors influence blood volume?
- fitness status,
- dehydration
- body size
How does the endocrine and urinary system manage blood volume?
Through hormones like ADH and aldosterone that regulate water and salt retention.
What is the Frank-Starling mechanism?
The strength of the heart’s contraction increases with an increase in venous return (end-diastolic volume).
What is the role of the autonomic nervous system in heart rate regulation?
It regulates heart rate through sympathetic (increases HR) and parasympathetic (decreases HR) nervous systems.
What is Ohm’s Law as applied to blood flow?
Flow (F) = ΔP / R, where ΔP is the pressure gradient and R is vascular resistance.
What is the difference between laminar and turbulent flow?
- Laminar flow is smooth and orderly.
- Turbulent flow is chaotic and can be caused by changes in vessel diameter or blood flow speed.
- B = laminar flow
- C = turbulent flow
What triggers vasoconstriction in the circulatory system?
The sympathetic nervous system, exercise, or stress.
What triggers vasodilation in the circulatory system?
The release of substances like bradykinin, histamine, or nitric oxide.
What is coronary blood flow?
Blood flow that supplies the heart muscle itself, primarily during diastole.
What is the effect of increased heart rate on myocardial oxygen consumption?
Increased heart rate leads to increased oxygen consumption by the heart muscle.
What is venous return?
The return of blood to the right side of the heart, influenced by venous pressure and total blood volume.
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What role does the thoracic pressure change during breathing play in venous return?
It creates pressure differences that promote blood flow back to the heart.
What is the function of the lymphatic system?
Removes excess fluid, waste, and other substances from tissues, preventing edema.
What is the cardiac cycle?
The sequence of events in one complete heartbeat, including systole (contraction) and diastole (relaxation).
What happens during isovolumic systole?
Both mitral and aortic valves are closed, and the ventricles contract without ejecting blood.
What is cardiac output?
The amount of blood the left ventricle pumps out every minute, calculated as Heart Rate (HR) x Stroke Volume (SV).
What is stroke volume?
The amount of blood ejected by the ventricle with each heartbeat.
What factors determine stroke volume?
- preload (EDV)
- contractility
- afterload (resistance)
What is preload?
The amount of blood returning to the heart, filling the ventricles before contraction.
What is afterload?
The resistance the heart must overcome to eject blood, mainly influenced by systemic vascular resistance.
What is ejection fraction?
The percentage of blood pumped out of the ventricles with each heartbeat, normally 60-70%.
What is the effect of sympathetic stimulation on the heart?
It increases heart rate and contractility through positive chronotropic and inotropic effects.
What is the effect of parasympathetic stimulation on the heart?
It decreases heart rate and contractility through negative chronotropic and inotropic effects.
What is mean arterial pressure (MAP)?
The average pressure in the arteries during one cardiac cycle, necessary for organ perfusion.
- MAP = 1/3 (PP) + DBP
- PP (Pulse Pressure) = SBP – DBP
- MAP = 1/3 (SBP –DBP) + DBP
What factors increase afterload?
Increased blood viscosity, vessel length, or decreased vessel radius.
What is the Bainbridge reflex?
A reflex that increases heart rate in response to increased venous return.
What is the baroreceptor reflex?
A reflex that helps maintain stable blood pressure by adjusting heart rate and vessel diameter.
What is the Valsalva maneuver?
A forced expiration against a closed glottis, affecting thoracic pressure and venous return.
What happens during ventricular systole?
The ventricles contract, ejecting blood into the aorta and pulmonary artery.
What is the role of nitric oxide in the cardiovascular system?
Nitric oxide acts as a vasodilator, helping to regulate blood pressure and blood flow.
What is congestive heart failure (CHF)?
A condition where the heart cannot pump efficiently, leading to fluid buildup in the lungs and other tissues.
What is the effect of aging on the cardiovascular system?
Aging leads to changes like increased left ventricular wall thickness, reduced cardiac output, and altered vascular function.
What is a positive inotropic effect?
An increase in the strength of heart muscle contraction.
What medications are used to increase inotropic effect in heart failure?
Medications like phosphodiesterase inhibitors (milrinone) and adrenergic agonists (epinephrine, dobutamine).
What is the significance of the pulse pressure (PP)?
The difference between systolic and diastolic pressure, indicative of the force that the heart generates with each contraction.
How does exercise affect cardiac output?
Exercise increases cardiac output by increasing both heart rate and stroke volume to meet the body’s increased oxygen demand.
What is a normal cardiac output at rest?
4-6 liters per minute.
What is the impact of beta-blockers on exercise?
Beta-blockers reduce heart rate response during exercise, making heart rate an unreliable measure of exercise intensity.
What is the Frank-Starling law of the heart?
The heart’s stroke volume increases in response to an increase in the volume of blood filling the heart.
What is the role of the adrenal medulla in cardiovascular regulation?
It releases hormones like epinephrine and norepinephrine that enhance heart rate and contractility during stress or exercise.
What is the significance of ejection fraction in assessing heart function?
Ejection fraction indicates how well the heart is pumping; values below 40% suggest heart failure.
What is the Bainbridge reflex, and when is it activated?
It’s activated by increased venous return, leading to an increase in heart rate to accommodate the extra blood volume.
