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What are the primary functions of the cardiovascular system?
Pump oxygenated blood to tissues, transport deoxygenated blood to lungs, and return blood for oxygenation.
Define blood flow.
The volume of blood passing a given point in the circulation per unit time (mL/min).
Define blood velocity.
The displacement of blood from one point to another in the circulation (cm/s).
What determines blood flow in the circulatory system?
Pressure gradient (ΔP) and resistance (R).
State the formula for blood flow (Ohm’s Law).
Blood Flow = ΔP / R.
What is a pressure gradient in the vascular system?
The difference in pressure between two points, driving blood flow from high to low pressure.
What is resistance in the vascular system?
Opposition to blood flow, influenced by vessel length, blood viscosity, and vessel radius.
How does vessel radius affect resistance?
Resistance is inversely proportional to the fourth power of the radius (R∝1r4R)
What is total peripheral resistance (TPR)?
The sum of all vascular resistances within systemic circulation.
What role do arterioles play in blood flow regulation?
Arterioles regulate blood flow to capillaries and control blood pressure through vasoconstriction and vasodilation.
What is vasoconstriction?
Narrowing of blood vessels due to smooth muscle contraction, increasing resistance and decreasing blood flow.
What is vasodilation?
Widening of blood vessels due to smooth muscle relaxation, decreasing resistance and increasing blood flow.
How does blood velocity relate to vessel cross-sectional area?
Blood velocity is inversely proportional to cross-sectional area; slowest in capillaries to maximize exchange.
Where is blood velocity highest?
In the aorta, due to the smallest total cross-sectional area.
Why is slow blood flow important in capillaries?
It allows efficient exchange of gases, nutrients, and waste products.
Define blood pressure (BP).
The pressure exerted by blood on the walls of blood vessels, expressed in mmHg.
How is mean arterial pressure (MAP) calculated?
MAP = 1/3(Systolic BP - Diastolic BP) + Diastolic BP.
What two factors determine blood pressure?
Cardiac output (CO) and total peripheral resistance (TPR).
What are the two short-term BP regulatory mechanisms?
Baroreceptor reflex and chemoreceptor reflex.
Where are baroreceptors located?
In the aortic arch and carotid sinus.
What is the baroreceptor response to increased BP?
It decreases heart rate and cardiac output by stimulating parasympathetic activity.
What is the baroreceptor response to decreased BP?
It increases heart rate and cardiac output by stimulating sympathetic activity.
What regulates long-term BP?
Blood volume, primarily controlled by the kidneys.
What is the renin-angiotensin-aldosterone system (RAAS)?
A hormone system that regulates BP and fluid balance by increasing sodium and water retention.
How does angiotensin II affect BP?
It increases BP by causing vasoconstriction, stimulating aldosterone secretion, and enhancing sodium and water reabsorption.
What is the role of antidiuretic hormone (ADH) in BP regulation?
It increases water reabsorption in the kidneys, raising blood volume and BP.
What does atrial natriuretic peptide (ANP) do?
It decreases BP by promoting sodium and water excretion,0 reducing blood volume.
Write the formula linking BP, CO, and TPR.
BP = CO × TPR.
What is the physiological effect of venoconstriction?
It increases venous return, end-diastolic volume (EDV), and stroke volume (SV).
Why is understanding vascular physiology important?
It helps in managing conditions like hypertension and ensuring proper perfusion to tissues.
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