EXSC384: Hormonal Control of Exercise

Explain the steps for the MOA direct gene activation

1. hormone enters cells

2. binds to receptor and forms HRC

3. HRC enters nucleus and activates cell’s DNA

4. formation of mRNA

5. mRNA leaves nucleus

6. within cytoplasm, mRNA directs protein synthesis

Explain the steps for the MOA I2CM

1. hormone binds to receptor and forms HRC

2. HRC activates adenylate cyclase

3. adenylate cyclase catalyzes the formation of cAMP

4. cAMP activates protein kinases

5. protein kinases carry out cellular effect

Cyclic AMP controls… (5)

1. activation of cellular enzymes

2. cellular metabolism

3. cellular secretion

4. protein synthesis

5. changes in membrane permeability

cAMP activates as a secondary messenger for… (3)

• glucagon

• epinephrine

• luteinizing hormone

What are the functions of prostaglandins? (3)

1. mediate the effects of other hormones

2. increase vascular permeability and vasodilation

3. sensitive nerve endings

What are the functions of growth hormone?

1. increase muscle growth and hypertrophy

2. stimulate lipolysis

3. inhibits CHO metabolism

4. stimulate the release of IGF-1

• released in response to muscle contraction

What does blood flow resistance (BFR) training do?

• increase release of IGF-1

• stimulates hypertrophy

What are the functions of the thyroid hormone? (6)

1. increase metabolic rate

2. increase protein synthesis

3. increase size and number of mitochondria

4. promote rapid cellular uptake of glucose

5. enhance glycolysis and glucogenolysis

6. enhance lipid mobilization

What are the hormones in the adernal cortex? (3)

1. mineralocorticoid → aldosterone

2. glucocorticoid → cortisol

3. gonadocorticoid 

What are the functions of catecholamines (epi & norepi)? (7)

1. increase HR

2. increase BP

3. increase respiration

4. redistribution of bloodflow

5. increase metabolic rate

6. increase release of glucose and FFA

7. increase glucogenolysis

What are the actions of insulin? (3)

1. facilitates glucose transport into cells

2. promotes glycolysis

3. inhibits glucogenlysis

What are the actions of glucagon? (4)

1. increased breakdown of liver glycogen

2. increased gluconeogensis

3. increased glycogenolysis

4. increased release of plasma glucose

What are the hormones that increase plasma glucose?

• epinephrine

• noriepinephrine

• cortisol

• glucagon

What is the only hormone used for brain metabolism?

glucose

Explain the steps of CNS-Endocrine system interaction (3)

1. insulin released by beta-cells acts through NGY/AgRP neurons

2. POMC neurons are stimulation by leptin and GLP-1

3. decrease liver glucose production

How does the regulation of fat metabolism occur?

• prolonged exercise = CHO depletion

• endocrine system can accelerate lipolysis

  • decreased insulin

  • epinephrine

  • norepinephrine

  • cortisol

  • growth hormone

How does fluid & electrolyte regulation occur?

Posterior pituitary is responsible for releasing ADH, water conservation, hemoconcentration, and osmolarity

The adrenal cortex secretes mineralocorticoids (aldosterone)

• electrolyte balance

Practice drawing out the kidneys & renin-angiotensin system

Make sure to relisten to the lecture recording to explain the process first :)

(insert practice)

Summarization Excitation Contraction Coupling (13)

1. AP moves down a-motor neuron (axon terminal)

2. synaptic vesicles release ACh

3. ACh binds to receptors on motor end plate

4. generates EPP

5. EPP travels down t-tubule

6. activates electrically charged gates

7. SR releases Ca2+

8. Ca2+ bind to 3rd subunit of troponin

9. confirmational shift of troponin

10. bind: myosin head attaches (ATP)

11. bend: myosin head moves

12. break: myosin head detaches (ATP)

13. bounce: myosin head returns to starting position

What direction are the transverse tubules and SR orientened within the sarcoplasm?

T-tubule: run laterally through muscle fibers

SR: run parallel to myofibrils (storage cite for Ca2+)

What is the basic functional unit of muscle?

sarcomere

What is contained within each of the sections within the sarcomere?

• I band

• A hand

• H zone

• M line

• Z disk

• I band = light zone, only thin filaments

• A hand = dark zone, thick & thin filaments

• H zone = contains only thick filaments

• M line = attachment site for myosin

• Z disk = attachment & stability for thin filaments

What is the function of titin?

• stabilize the myosin filaments

• stabilize sarcomere & center myosin filaments to middle

• providing increased force when muscles are stretched

• prevented the overstretching & damage to the sarcomere by resisting active stretching 

What is the function of nebulin

anchoring protein

What is the function of satellite cells?

• activated during muscular injury 

• follows chemotaxis (change in another substance")

• donates nucleus & increases protein synthesis for injured cell

What are the functions of troponin & tropomyosin?

troponin: causes actin and myosin to interact

tropomyosin: blocks actin binding site

What is a neuromuscular junction?

a connection between a synapse and a muscle fiber

What happens during muscle relaxation?

• Ca2+ is pumped back into SR by an active system

• troponin and tropomyosin return to resting conformation

• blocs actin & myosin from interacting

What is the difference between short and long term fatigue?

oxygen demand > oxygen supply

• use of anaerobic systems

• fatigues more quickly than the aerobic energy systems

• mitochondria cannot make ATP soon enough

What happens during muscular fatigue?

• a decline in signal transmission through the NMJ

• prior exercise & alcohol production decreases neural drive & decreases force production

What is neural drive?

the number of APs discharged by the motor neurons that innervate a muscle

What are the two ways of differentiating muscle fibers?

1. skin punch biopsy

2. muscle biopsy

Summarize the main differences between Type I & Type II muscle fibers based on the following categories:

• sarcoplasmic reticulum

• anaerobic or aerobic

• number of motor units/muscle fibers

• type of ATPase (CB cycling)

Type I

• SR: less developed, but better at delivering Ca2+ to muscle 

• aerobic

• smaller cell body (less than 300 MF) - less force

• slow ATPase (slow CB cycling)

Type II

• SR: more developed (obtains Ca2+ faster)

• anaerobic

• larger cell body (more than 300 MF) - more force

• fast ATPase (fast CB cycling)

What are the steps for a synapse reaction to occur? (6)

1. impulse reaches axon terminal

2. synaptic vesicles release NT

3. NT bind diffuse across synaptic cleft

4. NT bind to specialized post synaptic receptor

5. GP

6. AP

What occurs during an ascending tract?

• neural pathways carry sensory information through peripheral nerves and transmit to cerebral cortex

• somatosensory pathways

What occurs during a descending tract?

• motor signals are sent from the brain to lower motor neurons 

• pyramidal tract: responsible for voluntary control of musculature (ex: getting up from chair)

• extrapyramidal tract: responsible for involuntary control of musculature (ex: heart beat)

What is the function of the primary motor cortex?

• control of fine movement

What is the function of the premotor cortex?

• control of learned motor skills

What is the function of the basal ganglia?

• initiate sustained repetitive movements

• maintains posture & muscle tone

What is the function of the thalamus?

sensory integration

What is the function of the hypothalamus?

HOMEOSTASIS

• blood pressure

• sleep cycles

• digestion

• heart rate

• contractility

• respiration

• temperature

• thirst

• appetite

What is the function of the cerebellum?

timing and rapid progression

What is the function of the brain stem?

• origin of 10/12 CN

• holds the autonomic centers (respiratory, CV)

What is the function of the reticular formation?

• coordinate skeletal muscle formation

• maintain muscle tone

• CV & respiratory control

• determine state of consciousness

What is runner’s high caused by and what are the hormones released?

Caused by endurance exercise that increases the concentration of opioid like substance

• enkephalins

• beta-endorphins 

What is the pathway for sensory motor integration? (5)

1. stimulus is received by a sensory receptor

2. AP travels through sensory neurons to CNS

3. CNS interprets information & determines response

4. Motor AP travels out from CNS through motor neurons

5. AP reaches the muscle fibers & response occurs

What are the 4 sensory integration centers?

1. thalamus

2. cerebral cortex

3. cerebellum

4. brain stem

What are the three levels of motor response?

1. spinal cord - simple reflex - ex: hot stove

2. lower regions of brain - middle - ex: walking

3. motor area of the cerebral cortex - ex: backflip

How do you maintain RMP? (2)

1. permeability K+ > Na+

2. Na+/K+ pump

What is hyperpolarization?

inside of cells become more negative

Describe the steps of an AP (6)

1. RMP = -70 mV, Na+/K+ pump, K+ > Na+

2. Depolarization = Na+ channel, influx Na+

3. Overshoot = closing Na+ channel, open K+ channel

4. Repolarization = open K+ channel, efflux K+

5. K+ channels slow to close, extra negative on the inside

6. Return to RMP