Major Adjustments to Circulatory System During Exercise.

Question 1

Increase Cardiac Output (Q) Formula

Answer 1

(Q = HR * SV); Typical values at rest and during exercise depend on training state and gender

Question 2

Heart Rate (HR)

Answer 2

Number of beats per minute

Question 3

Stroke Volume (SV)

Answer 3

Amount of blood ejected in each beat

Question 4

Parasympathetic Nervous System

Answer 4

Via vagus nerve; Slows HR by inhibiting SA and AV Node

Question 5

Sympathetic Nervous System

Answer 5

Via cardiac accelerator nerves; Increases HR by stimulating SA and AV node

Question 6

Low resting HR due to…

Answer 6

Parasympathetic Tone

Question 7

Increase in HR at onset of exercise

Answer 7

1st parasympathetic withdrawal (up to ~100 bpm), 2nd increased SNS stimulation

Question 8

Expected Values for Untrained Male at Rest

Answer 8

72 b/min x 70 ml/beat = 5.00

Question 9

Expected Values for Untrained Female at Rest

Answer 9

75 b/min x 60 ml/beat = 4.50

Question 10

Expected Values for Trained Male at Rest

Answer 10

50 b/min x 100 ml/beat = 5.00

Question 11

Expected Values for Trained Female at Rest

Answer 11

55 b/min x 80 ml/beat = 4.40

Question 12

Expected Values for Untrained Male at Max Exercise

Answer 12

200 b/min x 110 ml/beat = 22.0

Question 13

Expected Values for Untrained Female at Max Exercise

Answer 13

200 b/min x 90 ml/beat = 18.0

Question 14

Expected Values for Trained Male at Max Exercise

Answer 14

190 b/min x 180 ml/beat = 34.2

Question 15

Expected Values for Trained Female at Max Exercise

Answer 15

190 b/min x 125 ml/min = 23.8

Question 16

End-Diastolic Volume (EDV)

Answer 16

Volume of blood in the ventricles at the end of diastolic (“Preload”)

Question 17

Average Aortic Blood Pressure

Answer 17

Pressure the heart must overcome to eject blood (“Afterload”)

Question 18

Strength of Ventricular contraction (contractility) is enhanced by

Answer 18

Circulating epinephrine and norepinephrine, Direct sympathetic stimulation of heart

Question 19

SV is influenced by:

Answer 19

Frank Starling Mechanism, Catecholamines

Question 20

Frank Starling Mechanism

Answer 20

(Only beneficial to 60% Max exercise) Greater EDV results in more forceful contraction due to stretch of ventricles (Length/Tension Relationship) and is dependent on venous return

Question 21

Venous return is influenced by:

Answer 21

1) Venoconstriction (via SNS), (2) Skeletal Muscle Pump (Skeletal muscle cx force blood back toward the heart, One-way valves in veins prevent backflow of blood), (3) Respiratory Pump (Changes in thoracic pressure pull blood toward heart)

Question 22

Catecholamines

Answer 22

influence stroke volume by increasing cardiac contractility by increasing the amount of calcium available to the myocardial cell; specifically increase the entry of extracellular calcium into the cardiac muscle fiber which increases cross bridge activation and force production

Question 23

Where does majority of blood goes at rest?

Answer 23

15-20% of cardiac output to muscle

Question 24

Where does majority of blood goes during exercise?

Answer 24

Increases to 80-85% during maximal exercise; Decreased blood flow to less active organs (Liver, Kidneys, GI Tract), Redistribution depends on metabolic rate (Exercise Intensity)

Question 25

Metabolic need:

Answer 25

Autoregulation refers to intrinsic control of blood flow by increases in local metabolites (e.g., nitric oxide, prostaglandins, ATP, adenosine, and endothelium-derived hyperpolarization factors). These factors work together to promote vasodilation to increase blood flow to the working muscles.

Question 26

The exercise-induced increase in local factors result in…

Answer 26

Increased vasodilation of arterioles/small arteries and promote increased blood flow to the contracting muscle in order to match the metabolic demand.

Question 27

Autoregulation

Answer 27

Blood flow increased to meet metabolic demands of tissue due to changes in O2 tension, CO2 tension, Nitric Oxide, Potassium, Adenosine, and pH

Question 28

Cardiovascular Control Center

Answer 28

Regulates vascular resistance in skeletal muscle decreases during exercise, vascular resistance to flow in the visceral organs and other inactivity tissue increases.

Question 29

As a result of the increase in visceral vasoconstriction during exercise (resistance increases):

Answer 29

blood flow to the viscera can decrease to only 20% to 30% of resting values