30 - Exercise Physiology I

Question 1

the essence of exercise is ________ not _____

Answer 1

physical activity NOT intent

Question 2

activity characterized by recurrent and substantial body movement

Answer 2

dynamic exercise

Question 3

muscle generates constant tension while changing length

Answer 3

isotonic contraction

Question 4

activity characterized by muscular contraction without substantial body movement

Answer 4

static exercise

Question 5

muscle generates tension without a change in length

Answer 5

isometric contraction

Question 6

concentric v. eccentric isotonic contraction

Answer 6

concentric - shortening muscle

eccentric - lengthening muscle

Question 7

blood flow to exercising muscle increases _______ to exercise intensity

Answer 7

in proportion to

Question 8

________ blood flow are reduced to the greatest extent

Answer 8

splanchnic and renal

Question 9

skeletal muscle pump

Answer 9

contracting muscles squeeze the veins and push blood back to the heart

Question 10

respiratory pump

Answer 10

during inspiration, pressure drops and increases venous return (gradient)

opposite with expiration

Question 11

thinly myelinated

sensitive to mechanical deformation

Answer 11

group III muscle afferent

Question 12

unmyelinated

metabolic byproducts associated with muscle contraction

Answer 12

group IV muscle afferents

Question 13

afferent projections synapse in the ______ and exert significant influence on __ and ____ respiratory function

Answer 13

nucleus of solitary tract

autonomic and respiratory function

Question 14

sympathetic n. activity _______ progressively with increasing exercise intensity —>

Answer 14

increases

–> increased arterial pressure, direct blood flow away from low-metabolically active tissue, venous return, and neurohumoral activation

Question 15

two phases of blood flow response to exercise

Answer 15

1. Initial increase: mechanical compression induced vasodilation and muscle pump
2. steady state exercise: vasodialtion in arterioles induced by metabolic substances (adenosine, K+, CO2, H+)

Question 16

_______ portion of the vascular tree most sensitive to metabolic vasodilators

Answer 16

terminal arterioles

• dilation of the terminal arterioles leads to recruitment of additional capillary networks

Question 17

___________: decreasing affinity of Hgb for O2 and ___ shifting the oxyhemoglobin dissociation curve

Answer 17

Bohr effect

right shift

–> more oxygen can be off-loaded at the muscle

Question 18

cardiovascular responses to exercise =
_ preload
_ contractility
_ HR
_ vascular resistance
_ SV
_ CO
_ BP

Answer 18

all increase except vascular resistance

Question 19

Increases in ventilation are well-matched to metabolic demands during ________ exercise. During ______, ventialtion and PaCO2 become uncoupled.

Answer 19

submaximal ; high intensity

–> CO2 levels decline in high intensity exercise

What mechanisms work to match ventilation and CO2 production? 1. Co2 flow to lung sensed with receptors 2. Central Command for conscious control 3. Mechano/metaboreceptors blocking III/IV afferents to reduce respiration

Question 20

in isometric exercises, BP ________ than in isotonic exercise

Answer 20

increases much more

why? 1. m. contraction compresses arteries, increasing resistance

Also observe… higher levels of central command and increased intra-abdmonal and intra-thoracic pressure

Question 21

Phases of Valsava Maneuver

Answer 21

I: increase intra-throacic pressure and compress aorta, veins, and heart. Reflex decrease in HR.

II: falling aortic pressure secondary to reduced CO. Reflex increase in HR.

III (done w/ maneuver): decreased compression of aorta.

IV: increased preload/cardiac filling/CO

Question 22

anticipate the metabolic demand associated with exercise and prevent significant perturbation to blood gas homeostasis and tissue oxygen supply

Answer 22

feed-forward mechanisms

Question 23

as exercise continues to increase in duration and intensity, _________ is thought to play a greater role

Answer 23

sympathetic activation

Question 24

what is though to account for the majority of early ehart rate response to exercise?

Answer 24

withdrawl of vagal tone