Blood Flow and Pressure

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Questions and Answers

Which phase of the cardiac cycle is characterized by the heart cells being at rest and the ventricles filling up with blood?

  • End-systolic volume (ESV)
  • End-diastolic volume (EDV)
  • Systole
  • Diastole (correct)

What is the equation for stroke volume (SV)?

  • SV = EDV + ESV
  • SV = EDV / ESV
  • SV = EDV - ESV (correct)
  • SV = EDV x ESV

Which factor affects stroke volume by representing the degree of stretching experienced by the heart muscle cell during diastole?

  • Muscle Pump
  • Preload (correct)
  • Gravity
  • Venous return

What happens to end-diastolic volume (EDV) and end-systolic volume (ESV) when you start exercising?

<p>EDV rises, ESV drops (A)</p> Signup and view all the answers

What is the average stroke volume (SV) per beat?

<p>About 70 mL (A)</p> Signup and view all the answers

Which factor affects the amount of blood returning to the heart and is influenced by gravity?

<p>Venous return (B)</p> Signup and view all the answers

What happens to stroke volume (SV) when the end-diastolic volume (EDV) increases and the end-systolic volume (ESV) decreases?

<p>Stroke volume increases (A)</p> Signup and view all the answers

Which of the following factors causes an increase in stroke volume during exercise?

<p>Venous return (C)</p> Signup and view all the answers

What is the equation for calculating ejection fraction?

<p>SV/EDV (A)</p> Signup and view all the answers

Which of the following is responsible for increasing heart rate during exercise?

<p>Sympathetic nervous system (C)</p> Signup and view all the answers

What is the equation for calculating cardiac output (Q)?

<p>Q = SV x HR (D)</p> Signup and view all the answers

Which of the following is true about systolic blood pressure (SBP) during exercise?

<p>It increases (D)</p> Signup and view all the answers

What is the equation for calculating mean arterial pressure (MAP)?

<p>MAP = â…“ SBP + â…” DBP (A)</p> Signup and view all the answers

What is the pulse pressure if the systolic blood pressure (SBP) is 120 mmHg and the diastolic blood pressure (DBP) is 80 mmHg?

<p>93.3 mmHg (B)</p> Signup and view all the answers

According to Poiseuille's Law, which of the following factors does NOT influence blood flow rate?

<p>Length of tubing (C)</p> Signup and view all the answers

Which of the following statements about vasodilation is correct?

<p>Vasodilation is influenced by hormones, metabolites, and shear stress (A)</p> Signup and view all the answers

What is the relationship between flow, pressure, and resistance according to the equation Q = \frac{P},{R}?

<p>Flow is directly proportional to pressure and inversely proportional to resistance (B)</p> Signup and view all the answers

Which of the following factors does NOT affect blood flow distribution?

<p>Blood pressure (B)</p> Signup and view all the answers

What is the relationship between viscosity, shear stress, and shear rate according to the equation \eta = \frac{\tau},{\dot{\gamma}}?

<p>Viscosity is directly proportional to shear stress and inversely proportional to shear rate (B)</p> Signup and view all the answers

During static exercise, which of the following factors does NOT contribute to decreased stroke volume?

<p>Pressor response (C)</p> Signup and view all the answers

Which of the following statements about blood flow distribution is correct?

<p>The skeletal muscles receive the highest percentage of blood flow during maximal aerobic exercise (B)</p> Signup and view all the answers

Which type of exercise, static or dynamic, is associated with a greater increase in heart rate?

<p>Dynamic (A)</p> Signup and view all the answers

During dynamic exercise, why is there not much increase in blood flow until the muscle relaxes?

<p>Because the blood vessels are occluded (D)</p> Signup and view all the answers

Which gender has higher cardiac output (Q) and heart rate (HR), but lower stroke volume (SV) at the same absolute work rate?

<p>Females (C)</p> Signup and view all the answers

Which gender has a smaller heart size, males or females?

<p>Females (A)</p> Signup and view all the answers

Which parameter is higher in males: red blood cell (RBC) count or hematocrit (Hb)?

<p>Red blood cell (RBC) count (D)</p> Signup and view all the answers

In aging individuals, which parameter tends to be smaller and which tends to be higher at the same absolute heart rate (HR): stroke volume (SV) and heart rate (HR)?

<p>SV smaller, HR higher (B)</p> Signup and view all the answers

In older individuals, is resting blood pressure (BP) higher or lower compared to younger individuals?

<p>Higher (B)</p> Signup and view all the answers

In older individuals, is exercise blood pressure (BP) higher or lower compared to younger individuals?

<p>Higher (D)</p> Signup and view all the answers

Which type of exercise, static or dynamic, allows a bigger volume of blood to be pumped around the body?

<p>Dynamic (D)</p> Signup and view all the answers

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Study Notes

Cardiac Cycle and Stroke Volume

  • Diastole Phase: Characterized by the heart at rest and ventricles filling with blood.
  • Stroke Volume (SV) Equation: SV = End-Diastolic Volume (EDV) - End-Systolic Volume (ESV).
  • Preload: The degree of stretching of the heart muscle cells during diastole affects stroke volume.

Exercise Effects on Volumes and Stroke Volume

  • End-Diastolic Volume (EDV) & End-Systolic Volume (ESV): Both EDV increases and ESV decreases during exercise.
  • Average Stroke Volume: Approximately 70 mL per beat in a healthy adult.
  • Venous Return Influences: Factors like gravity affect blood returning to the heart.

Stroke Volume Changes

  • Increased EDV and Decreased ESV: Lead to an increase in stroke volume.
  • Factors Increasing Stroke Volume During Exercise: Increased preload and heart rate contribute to higher stroke volume.

Cardiac Output and Ejection Fraction

  • Ejection Fraction Calculation: EF = (Stroke Volume / End-Diastolic Volume) x 100%.
  • Cardiac Output (Q) Equation: Q = Heart Rate (HR) x Stroke Volume (SV).

Blood Pressure Dynamics

  • Systolic Blood Pressure (SBP) During Exercise: Typically increases with exercise intensity.
  • Mean Arterial Pressure (MAP) Equation: MAP = DBP + 1/3(SBP - DBP).
  • Pulse Pressure Calculation: Pulse Pressure = SBP - DBP = 120 mmHg - 80 mmHg = 40 mmHg.

Blood Flow and Vasodilation

  • Poiseuille's Law: Factors influencing blood flow rate include radius, viscosity, and pressure difference; flow rate is unaffected by blood viscosity changes at low Re (Reynolds number).
  • Vasodilation Effects: Leads to increased blood flow by widening blood vessels.

Relationship in Circulatory Dynamics

  • Flow, Pressure, and Resistance Equation: Q = P / R indicates inversely proportional relationships between resistance and flow.
  • Viscosity and Shear Stress: Related by η = Ï„ / ɣ̇, where η is viscosity, Ï„ is shear stress, and ɣ̇ is shear rate.

Static vs. Dynamic Exercise Effects

  • Static Exercise: Less contribution to decreased stroke volume compared to dynamic exercise.
  • Dynamic vs. Static: Dynamic exercise typically results in a greater increase in heart rate.

Gender Differences

  • Cardiac Output and Stroke Volume: Females generally have higher HR and Q but lower SV than males at the same absolute work rate.
  • Heart Size: Males possess a larger heart size compared to females.
  • Red Blood Cell Count: Males typically have higher RBC count and hematocrit levels.

Aging Population Dynamics

  • Stroke Volume and Heart Rate: Older individuals tend to have smaller stroke volumes and higher heart rates at the same absolute HR.
  • Blood Pressure Changes: Resting and exercise BP is generally higher in older individuals compared to younger counterparts.
  • Dynamic Exercise Efficiency: Dynamic exercise is more effective in allowing larger volumes of blood to be pumped around the body compared to static exercise.

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