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
