1. Intro & Key Concepts Flashcards
What is exercise physiology?
- Study of adjustments made by biological organisms, beyond resting homeostasis, in order to create or sustain “exercise”
- Study of “intense living” (as indicated by elevated metabolism or force production) and how we survive it
What are some rapid fluxes that occur during “intense living” (exercise)?
- Mean arterial blood pressure rises due to vasodilation of muscle
- Temp regulation
- PCO2
- PO2
- Increase glucose uptake 7-20 fold
- Lower pH b/c increased lactate
Explain the rapid flux of blood glucose during exercise. What occurs at rest vs. during exercise?
-Total of 18 Kcals of glucose in blood
AT REST:
-rate of glucose use is 1.75 Kcal / 5 mins
-if no glucose replacement into blood, one depletes blood glucose by half in ~42 mins –> results in severe brain dysfunction
DURING EXERCISE (80% VO2max):
-rate of glucose use = 16.2 Kcal/min (46x resting rate)
-if no glucose replacement into blood, one depletes blood glucose by half in 33 seconds
Acute vs. Chronic exercise
ACUTE: -a single work bout -physiologic responses -often via rapid, temporary neuro-endocrine changes CHRONIC: -repeated work bouts, aka "training" -physiologic adaptations (body changes) -often via structural changes (ex. heart growth), or altered regulatory functions (ex. slowed HR)
What is homeostasis?
Dynamic equilibrium maintained by an organism w/ its environment in order to maintain biologically critical variables relatively constant
Explain the relationships between cells, body systems, and homeostasis.
- Cells make up body systems
- Body systems maintain homeostasis
- Homeostasis is essential for the survival of cells
What are the components of a biological control system? How does each react to stressors to maintain homeostasis?
- negative feedback loop*
1. Stimulus (stress) excites receptor (+)
2. Receptor signals the integrating center of a disturbance (+)
3. Integrating center signals effector to correct disturbance (+)
4. Effector corrects disturbance and removes stimulus (-)
Stress vs. Stressor. Examples?
STRESSOR:
-An environmental factor that displaces the body from equilibrium (homeostatic) conditions
-ex) exercise work rate, thermal load, high altitude
STRESS:
-Passive, “unwanted” bodily displacement specific to a certain stressor
-increased body temp b/c of thermal load
-ex) decreased oxygen in blood b/c high altitude
What is a response? Characterized by what?
- Seeks to limit or correct the acute displacement (stress)
- Active, energetically expensive
- Characterized by changes in controlled variables to stabilize regulated variables
Regulated vs. Controlled variables. Examples?
REGULATED: -targets of homeostasis -biologically critical -change very little (very narrow range) -ex) MAP, blood glucose, body temp, pH CONTROLLED: -change to minimize displacement of regulated variables -ex) cardiac output, insulin, glucagon, sweating
List the special, ultra rapid response mechanisms of negative feedback.
- Feed forward
- Central command / Central Co-activation
Describe the feed forward response mechanism of exercise. Examples?
Response to a peripheral phenomenon that precedes the actual stress
-many enzymes, via allosteric effectors
Describe the central command response mechanism of exercise. Examples?
CNS institutes correction of the problem even as it starts the problem
- many cardiovascular & ventilation responses to onset of exercise
- ex) CNS activates muscles during exercise –> w/in 5-10 seconds, higher breathing levels
What is allostasis? How does it become established? Aka?
- If the level of stressor is w/in the adaptive range of the organism –> a new dynamic equilibrium is established
- Aka “steady-state” or heterostasis
Define fatigue.
Inability to sustain force/work rate in a single bout
What is adaptive failure?
Inability to tolerate repeated bouts
Responses vs. Adaptations
RESPONSES:
-short-term adjustments to a single bout of exercise
-leave no lasting change
ADAPTATIONS:
-longer term adjustments to repeated or chronic exercise stressors
-structural changes
-measurable alterations in regulatory functions
In its original definition, homeostasis referred to the stability of which body fluid compartment?
Extracellular fluid
How is steady state body temp during exercise different from resting?
Steady state body temp is slightly higher during exercise than when at rest
In response to exercise in heat (stressor), what are the stress, response, and adaptations?
- Stress = increased core body temp
- Response = sweating, vasodilation
- Adaptations = increased plasma volume, increased threshold & gain
In response to sustained exercise (stressor), what are the stress, response, and adaptations?
- Stress = increased aerobic metabolism in skeletal muscle
- Response = increased cardiac output
- Adaptations = increased cardiac dimensions, increased HR & SV
