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Why are the effects of the endocrine system considered global?
- They're considered global because anywhere there is a receptor for the hormone, the receptor will be affected.
- This system allows for activity for organs that dont receive neural stimulation.
What are the different types of hormones we discussed? Which are water soluble? Why is this important?
Peptide: WATER SOLUBLE. Cannot transverse phospholipid bilayer. Relies on receptors on cell membrane. Requires 2nd messenger system to exert effect.
Steroid: Cholesterol base, fat soluble, able to transverse phospholipid bilayer to attach to receptors inside a cell. Gene transcription.
What are second messengers? What's the name of the one we talked about? What's the mechanism of it's action?
- Second messengers allow a hormone (peptide) to exert effect w/o entering cell.
- We spoke about cAMP: the hormone acts as a first messenger to react with the enzyme adenlyate cyclase (which is in the plasma membrane) to form the compound cAMP from ATP.
- cAMP acts as a second messenger to active a protein kinase, which leads to the desired biological activity.
What is the master gland? What hormone are released from here?
- The pituitary gland is the master gland.
- Ant. Pit.: GH, TSH, ACTH, LS/FSH, Prolactin
- Post. Pit.: Oxytocin and ADH
- ADH, GH and TSH are important for exercise.
What is the effect of ADH and how does it work?
- ADH is Anti-diuretic Hormone: In response to dehydration (a decreasing PV), it decreases urination by acting directly on the kidney, causing H2O reabsorption.
- It also stimulates thirst.
What effect does Growth Hormone have on fat metabolism? Protein metabolism?
GH: Increases use of fatty accids for energy and protein synthesis
What's the risk of taking exogenous Growth Hormone? When is GH normally released?
- Since GH makes tissues grow, taking extra GH increases risk for cancer. It's also diabetogenic causing type 1 diabetes.
- It's release is based on diurnal rhythm: Peaks during 1st hour of sleep.
What's the primary effect of thyroid hormone? What does TH bind to? How does this affect metabolism?
- TH Primary effect: Increases Oxygen uptake, regulates metabolic rate.
- It binds to mitochondria.
- When we exercise we increase formation of mitochondria, giving way to more TH binding sites, which helps burn more calories at rest.
- More muscle=More mitochondria.
- Exercise=Increased Metabolic Rate
How does exercise training combine with TH to affect caloric balance?
You burn more calories with the help of the increased mitochondria allowing TH to bind to more.
What are catecholamines? Name them.
- They are peptide hormones released from Adrenal Medulla that bind to alpha/beta receptors.
- Epinephrine and Norepinephrine.
What systems in the body do catecholamines affect?
- The Nervous Sys. stimulates their release.
- Their effects are relative to exercise:
- Increase HR
- Increase Contractility
- Bronchiodilation (maintain lung diffusion gradient, ex. inhalers have epinephrine)
Where are insulin and glucagon are peptide hormones released from? What stimulates their release?
- Insulin and Glucagon are released from the Pancreas. They must maintain blood glucose
- They're sensitive to Blood glucose:
- If BG is high, Insulin is released.
- Low, Glucagon is released.
What is Glut4?
Glut4 is a transport protein, used to transport glucose into the cell.
How does exercise affect glucose transport? How is this significant for diabetics?
- Exercise releases Calcium in the muscle cells, which causes an increase in glucose sensitivity.
- With glucose sensitivity, we'll need less insulin for glucose release, helping to prevent or manage risk of diabetes.
How is an elevated glucagon beneficial to the exercise response?
It signals the liver to release glucose into the blood to supply muscle cells. It also signals for Gluconeogenesis, for further glucose formation.
What duration and intensity intervals will best increase VO2max in athletes? How much rest should accompany these intervals?
HIIE: High Intensity Intermittent Interval Exercise. Short exercise with long rest.
What duration intervals promote increases in glycolytic capacity? What is the optimal work to rest ratio for glycolytic intervals?
- Duration: 1-2 minutes
- Recovery is 2:1, so its twice as long as the exercise.
How can you improve the phosphagen energy system? What are the two primary principles we discussed?
- Duration: Less than 1 minute.
- Recovery 3:1, 3x longer, os 3-5 minute
- Intense exercise.
What effect does HIIE have on VO2max? Which is more effect is increasing VO2max: HIIE, or steady exercise?
- HIIE increases VO2max.
- HIIE is more effective.
- How + why
Which burns more calories: HIIE or steady exercise?
Does HIIE have an effect on weight loss?
Yes, great effect.
Which is likely most effective in targeting abdominal fat losses: HIIE or steady exercise?
What is muscular strength? How can we use weight training to increase it? How can we induce muscular hypertrophy using weight training?
- Muscular strength is tension developed in muscle.
- To increase strength with weight training, the key is VOLUME: Volume=weight x reps
- Reccomended to train @ 75% of 1RM, 3x10. Hypertrophy tends to happen after 12 weeks.
When we sweat, which fluid compartment is affected the most? What affect does this have on the CV system? How much of a fluid loss does it take to affect VO2max?
- Plasma volume is affected most by fluid loss.
- Less PV means decreased CV function: @ 1% loss, theres impaired CV function
- @ 3%, decrease in VO2max.
Why is a 6% CHO solution considered superior to water for fluid replacement?
6% CHO solution is more isotonic than water, so we get more intestinal absorption. Allows more fluid to be absorbed than urinated.
How can we acclimate to heat? How does our physiology change with heat acclimation?
- To acclimate we need exposure to heat
- Low intensity (~40-50% VO2max)
- For athletes, 60 minutes, (regular humans 30)
- Acclimation will have in 4-10 days.
- Physiologically, our PV increases because of an earlier sweat response which increases sweat capacity and better evaporative cooling, which conserves sodium loss.
Explain how altitude changes the inspired partial pressure of O2.
At higher altitudes there is lower barometric pressure, which causes a decrease in aveolar-arterial gradient, causing hypoxia.
What are the immediate responses to altitude?
- Inc. alkalinity due to loss of HCO3-
- Diruesis (inc. urine volume, lower BV, slows down blood, allowing O2 to stick to RBCs
- Decrease in SaO2
- Decrease in VO2max
What chronic adaptations at altitude take place to help increase O2 transport?
- Increased RBC production
- Renal Compensation (Kidneys release excess HCO3-)
- Ventilatory acclimatization
- Reduced muscle mass
- Improved SaO2
- Decreased VO2max
Why is altitude training so popular?
- It's popular due to the chronic altitude exposure adaptations:
- Inc. RBC mass
- Inc. Capillary density
- Inc. FFA Utilization
- Inc. Oxidative capacity
Will altitude help or hurt athletes that are involved in power events?
- Yes: It causes muscular atrophy and detraining due to reduced training intensity and chronic adaptation.
- Less HCO3- means blood is alkalytic.
WHy is it that VO2max doesnt increase after chronic exposure to altitude?
- VO2max decreases the higher the altitude.
- SL VO2max is not regained after acclimatization.
- Decrease in mitochondria.
- So, despite an increase in RBC and cap. density, it's balances out from the decrease in mitochondria, allowing no change in VO2max. Even though we can deliver more, there's nothing more to deliver it to.
WHy is altitude training potentially detrimental to endurance performance?
It causes muscular atrophy, and a decrease in Bicarbonate in the blood, causing it to become alkaline. These factors contribute to a Reduction in Training Activity
Why is LHTL the new answer to the altitude training question?
- Is it? I thought it was LLTH.
- This is because this method does not allow for Intermittant Hypoxic Exposure. So you reap the benefits that altitude bestows upon training ( INC RBC MASS, INC. CAP DENSE, INC. FFA UTIL., INC. OXI CAP), but you avoid the detriments (Reduced training intensity, muscular atrophy, decrease in HCO3-) by reducing exposure to just training
WHat's AMS? What are the first signs of it? WHy is it dangerous?
Acute Mountain Sickness. Headache, nausea, lethargy, no appetite. Lethal if not treated because it can lead to HACE or HAPE
What does HACE stand for?
- High altitude cerebral edema:
- Swelling of frontal lobe, headaches
What can we do if someone is suffering from AMS?
- Give them acetazolamide.
- It's a diuretic, allowing us to pee and blood to become more acidic which helps breathing.
What percentage of people develop AMS on Mt. Whitney? What factors are protective of AMS?
- Protective factors:
- Prior Acclimatization.