Ex phys Wk 1&2

Question 1

Purpose of cardiovascular system?

Answer 1

• Transport of O2 to tissues and removal of wastes,
• Transport of nutrients to tissues, and
• Regulation of body temperature.
• Protection

Question 2

Where does the left and right side of heart pump blood to?

Answer 2

The heart is two pumps in one.

• Right side pumps blood through the pulmonary circulation
• Left side delivers blood to the systemic circulation.

Question 3

What is the contraction and relaxation phase of the cardiac cycle?

Answer 3

Contraction phase = systole

Relaxation= diastole

Question 4

What node is the pacemaker of the heart?

Answer 4

SA node - Sinoatrial

Question 5

What is the average blood pressure during a cardiac cycle called?

Answer 5

Mean arterial pressure

Question 6

What does PNS activity
and
SNS activity
do to the HR

Answer 6

PNS activity slows HR

SNS activity speeds it up

Question 7

Why does Heart Rate increase at beginning of exercise?

Answer 7

Due to a withdrawal of parasympathetic tone. At higher work rates, the increase in heart rate is achieved via an increased sympathetic outflow to the SA node.

Question 8

What is stroke volume regulated by?

Answer 8

1. EDV
2. aortic blood pressure, and
3. the strength of ventricular contraction.

Question 9

Venous return increases during exercise due to?

Answer 9

1. Venoconstriction
2. Muscle pump
3. Respiratory pump

Question 10

What are the adjustments to HR at commencement of exercise (immediate)

Answer 10

1. Anticipatory rise in HR
2. Response to exercise
   
   1. Increased neural activity
   2. Muscle and joint mechanoreceptor reflexes
   3. Muscle chemoreceptor reflexes
   4. Circulating Hormones
      
      1. Ep and Norep
   5. Intrinsic Factors
      
      1. Frank Starling Law
         
         1. Factors affecting EDV…
      2. Increased temp during exercise

Question 11

What are the two principle components of blood?

Answer 11

Plasma

Cells

Question 12

What is blood flow through the vascular system directly and inversely proportional to?

Answer 12

• Directly proportional to the pressure at the two ends of the system
• Inversely proportional to resistance

Question 13

What is the most important factor determining resistance to blood flow in the blood vessel?

Answer 13

The radius of the blood vessel

Question 14

Where is the greatest resistance to blood flow offered in?

Answer 14

The arterioles

Question 15

What are the changes in HR and BP occurring during exercise a function of?

Answer 15

The

• duration
• type and intensity of exercise performed
• environmental conditions.

Question 16

At the same level of oxygen consumption, are HR and BP greater during leg or arm exercise?

Answer 16

Arm exercise

Question 17

What is Cardiovascular drift?

Answer 17

The increase in HR occurring during prolonged exercise

Question 18

What does the central command theory of cardiovascular control during exercise propose?

Answer 18

The initial signal to “drive” the cardiovascular system at the beginning of exercise comes from higher brain centres.

Question 19

What is the cardiovascular response to exercise fine tuned by?

Answer 19

• feedback from muscle chemoreceptors
• muscle mechanoreceptors
• arterial baroreceptors to the cardiovascular control centre.

Question 20

Major purposes of cardiovascular system?

Answer 20

• Transport O2 and nutrients to tissues
• Removal of CO2 wastes from tissues
• Regulation of body temperature

Question 21

Briefly, outline the design of the heart. Why is the heart often called “two pumps in one”?

Answer 21

“two pumps in one” = 2 circuits - pulmonary (right) and systemic (left)

• Pulmonary Circulation
  a. Pumps deoxygenated blood to lungs by pulmonary arteries
  b. Returns oxygenated blood to left side of heart by pulmonary veins
• Systemic Circulation
  a. Pumps oxygenated blood to whole body by arteries
  b. Return deoxygenated blood to left side by veins

Question 22

Outline the cardiac cycle and the associated electrical activity recorded via the electrocardiogram.

Answer 22

• Systole (contraction/ejection of blood). 2/3 of blood ejected per beat
  a. AV valves open and blood pumped into aorta and pulmonary artery
  b. “Dub” sound when Semilunar valves close
• Diastole (relaxation/filling of blood)
  a. blood flows into left and right atria
  b. Semilunar valves open and SA node contracts causing depolarization
  c. Blood dumped into ventricles
  d. AV valves close causing “lub” sound
• Pulse pressure: difference systolic and diastolic
• MAP= DBP + 1/3 Pulse Pressure OR
  MAP= CO x Total Vascular Resistance

EKG

• P wave: atrial depolarization (started by SA node)
• QRS wave: ventricular depolarization (passed by AV node) and atrial repolarization
• T wave: ventricular repolarization
• ST segment depression can indicate myocardial ischemia

Question 23

Graph the heart rate, stroke volume, and cardiac output response to incremental exercise.

Answer 23

• Heart rate: increases linearly towards max
• SV: increases and then plateaus ~40-60% VO2 max (no plateau in trained subjects)
• CO: increases linearly

Question 24

What factors regulate heart rate during exercise? Stroke volume?

Answer 24

Heart Rate

• Parasympathetic: decreases HR by inhibiting SA and AV node through the vagus nerve
• Sympathetic: Increases HR by stimulating SA and AV node through cardiac accelerator nerve

Stroke Volume

• End diastolic volume: volume of blood in the ventricles at the end of diastole
• MAP: pressure heart pumps against
• Strength of ventricular contraction. Enhanced by epinephrine/NE and sympathetic stimulation.

Question 25

How does exercise influence venous return?

Answer 25

- Venoconstriction: - Muscle pump: rhythmic skeletal muscle contractions force blood in the extremities toward the heart - Respiratory pump: changes in thoracic pressure pull blood toward heart - Change in pressure: difference b/w MAP and right atrial pressure - Resistance a. MOST important is radius of vessel b. length of vessel c. viscosity of blood - Large arteries and arterioles are resistance vessels. Arterioles offer greatest resistance to blood flow and greatest drop in pressure.

Question 26

What factors determine local blood flow during exercise?

Answer 26

- Skeletal muscle vasodilation a. Autoregulation b. Due to changes in O2 tension, CO2 tension, nitric oxide, potassium, adenosine, and pH - Vasoconstriction to visceral organs and inactive tissues

Question 27

Graph the changes that occur in heart rate, stroke volume, and cardiac output during prolonged exercise. What happens to these variables if the exercise is performed in a hot/humid environment?

Answer 27

- HR: gradual increase towards max - SV: gradual decrease due to dehydration and reduced plasma volume - CO: maintained at high level - Hot/humid environment a. HR: increases b. SV: decreases c. CO: increases

Question 28

Compare heart rate and blood pressure responses to arm and leg work at the same oxygen uptake. What factors might explain the observed differences?

Answer 28

- HR: higher during arm workout than leg workout a. Due to higher sympathetic stimulation - BP: higher during arm workout than leg workout a. Due to vasoconstriction of large inactive muscle mass

Question 29

Explain the central command theory of cardiovascular regulation during exercise.

Answer 29

- Proposes that the initial signal to "drive" the cardiovascular system at the beginning of exercise comes from higher brain centers - Cardiovascular response to exercise is fine-tuned by feedback from muscle chemoreceptors, muscle mechanoreceptors, and arterial baroreceptors to the cardiovascular control center.

Question 30

What percentage of the total amount of oxygen transported in aterial blood is bound to Haemoglobin? How is the remainder transported?

Answer 30

Haemoglobin holds 98 percent of the oxygen that is delivered by aterial blood overall. After being physically dissolved in plasma, the final 2 percent is transferred.

Question 31

What are two other functions of Haemoglobin in the body? Give brief details

Answer 31

1) Hb carries C02: C02 binds to Hb, molecule carbaminohaemoglobin is formed. Bind is reversible. When at lungs, C02 can freely dislocated from Hb and leave body. 2) Hb as a buffer: Major buffer system in red cell. Its buffer power is strengthened through the Haldane effect. - Hydrogen ions are buffered to Hb

Question 32

Explain in your own words what blood viscosity is:

Answer 32

- The measurement of the resistance of blood flow when its being stretched or sheared. - Usually caused by deformity in the RBC shape or components of blood are elevated. -There are different variation such as the vera tumour, Hct which rises, its problematic because it raises blood viscosity, which raises blood pressure.

Question 33

Explain the typical sequence of events, which accompany: a) the regulation of a high blood glucose level b) the regulation of a low blood glucose level Refer to specific hormones

Answer 33

a) BGL increase after meal. when BSL rise, cells in pancreas release insulin, causing body to absorb glucose from the blood and lowering the BSL to normal Type 1 diabetes Hormone = Insulin to decrease BGL b) BGL drops too low, Insulin level decreases and other cells in pancreas release glucagon, causing liver to turn stored oxygen back into glucose and release into blood. Type 2 Hormone = Glycogen increase BGL