Endocrine System (Chapter 8) Flashcards
Two major systems of communication in the body
- endocrine
- nervous
Endocrine systems sends signals causing
- physiological response (acute)
- adaptations (chronic)
Hormones
- chemical released from glands in response to mechanical chemical, neural, or hormonal stimulation
- changes the function of a cell or tissue
- specific receptors
- blood is major transport
Exercise effect on endocrine system
- muscle growth and repair
- CT repair and remodeling
- blood glucose control
- adipose and blood fat levels
- extrinsic control of HR and SV
- done density
- fluid and electrolyte balance and hydration
Steroid hormones
- derived from cholesterol
- diffuse easily through cell membrane (act directly on
DNA in cell) - anabolic or catabolic
- corticosteroid (cortisol-like, man made)
Name the steroid hormones
- testosterone
- estrogen
- aldosterone
Peptide hormones
- composed of various sequences of amino acid
- cannot diffuse through cell membrane
- receptors on outside of cell
- need a secondary messenger to stimulate DNA
- very common
Name the peptide hormones
- growth hormone
- beta-endorphin
- antidiuretic hormone
- oxytocin
- thyroid stimulating hormone
Amine hormones
- contain nitrogen with various types of alkyl groups
- quick to break down
- cannot diffuse through cell membrane
- receptors on outside of cell
- need a secondary messenger to stimulate DNA
- catecholamines (fight or flight)
Name the amine hormones
Endocrine hormone transport
- secreted directly into bloodstream
Paracrine hormone transport
- released and acts on nearby cells
- neurohormones
- neurotransmitters
- adipocytes releasing leptin to affect nearby fat cells
- WBC releasing cytokines and hormones
Autocrine hormone transport
released and acts on the cell that released it
Plasma levels
- production vs half-life
- up and down regulation
Circadian rhythms
- regulation fluctuation
Circadian rhythms impact hormones response to exercise when?
- some are low in the morning then peak later
- other peak in morning and decline thought-out the
day
Circadian response patterns are sensitive to?
- light and dark cycles
- sleep patterns
- seasonal changes
What regulates secretion
feedback systems
Negative feedback
- hormone or its effect causes the gland to dec secretion
- reduces effect to return to initial status
Positive feedback
- hormone or its effect causes the gland to inc secretion
- inc effect to continue moving away from the initial status
multiple feedback influences
redundant regulation (multiple hormones)
Hypothalamus
- controls function of pituitary gland
- responds to stimuli and/or feedback loops by secreting “releasing” or “inhibiting” hormones
pituitary gland
- “master gland”
- releases peptide hormones
- small endocrine gland located just below brain
- the hormones released influence many physiological
functions
Growth hormone
- not a steroid
- anabolic
- stimulated by exercise stress
Effects and influences of growth hormones
- muscle fibers
- protein synthesis
- adipose cells, breakdown of triglycerides not allowing uptake of lipids
- other tissues, bones, and CT growth
Resistance training and growth hormones
- high volume, moderately heavy, and short rest
- maximizes release during recovery
- released in pulses or bust
- production reduces with age but there is much variability
Beta-endorphin
- analgesic effect, partially responsible for “runners high”
- levels in in response to all types of exercise
- the harder the workout the more produced
Antidiuretic hormone (ADH)
- causes kidneys to reabsorb water
- dec urination
- stimulated by inc blood osmolarity
- diuretic blacks ADH
Oxytocin
- creates contraction during labor
- positive feedback loop
Thyroid stimulating hormone (stimulating hormone)
- stimulates thyroid and calcitonin
- controls metabolic rate, growth and development, and metabolism of fats, proteins, and carbs
- iodine is needed for synthesize
Adrenocorticotropin (stimulating hormone)
- stimulates cortisol production
Gonadotropin releasing hormone (GnRH)
- GnRH from the hypothalamus causes pituitary to release luteinizing hormone and follicle stimulating hormone
Gonads
- steroid hormone
- sex hormones
Testosterone
- released by gonads
- most potent anabolic hormone in men
- builds muscle, bone mass, strength, and libido
- 10-30 times lower in women
- inc by exercise
Estrogen
- released by gonads
- promotes female sex traits
- regulates the menstrual cycle
- exercise influence on menstrual cycle
- amenorrhea related to overtraining (linked with malnutrition)
liver
- releases peptide hormones
Insulin-like growth factor (IGFs)
- released by liver
- peptides and binding proteins
- stimulate muscle fibers repair and growth
-signaling systems are complex and are still not understood - effects on target cells can be carried out by endocrine, paracrine, and autocrine
Kidneys
- release peptide hormones
Erythropoietin (EPO)
- released by the kidney
- promotes RBC production by stimulating bone marrow
- stimulated by low hematocrit (cased by training/altitude)
Adrenal gland
- assists in response to stress
- located on top of kidney
- adrenal cortex (outer part)
- adrenal medulla (inner part)
Adrenal gland influences
- high intensity exercise
- recovery from exercise stress
Adrenal medulla
- releases amine hormones
- stimulated by SNS to prepare for immediate action
Catecholamines (epinephrine)
- released by adrenal medulla
- 85% of total catecholamines
- causes an inc HR, contractility of heart, BP, and respiration
- metabolic rate, glycogenolysis, and release of glucose and fatty acid into blood
- faster Ca release from SR
Neurotransmitters
norepinephrine and dopamine
stimulation related to intensity
- slight inc in blood levels before exercise
- helps physiological preparation
- significant inc about 50% of VO2 max
- exponential inc as exercise reaches max levels
- quick recovery to resting levels (quick breakdown)
Adrenal cortex
- releases steroid hormones
- stimulated by other hormones
- adrenocorticotropin
- angiotensin II
- mineralocorticoids regulate electrolytes and water
aldosterone
- regulates water balance and electrolytes in blood by regulating tubules and CD in kidney
- signal kidney to retain sodium and secrete potassium
- inc BP/V by causing water retention
- helps balance pH by excreting H+ and releasing bicarbonate into blood
- stimulates release of an diuretic hormone
- stimulated by dec BP/V
glucocorticoids
- regulates sugar
Cortisol (glucocorticoids)
- primary catabolic hormone in the body
- protein, glycogen, and fatty acid from adipose tissue breakdown
- preserve plasma glucose levels
- glycogenesis from fat and amino acids
- limits glucose absorption (counteracts insulin)
- anti-flammatory function, suppresses immune cell function
- slow recovery, block protein synthesis and suppresses tissue repair
Cortisol is increased by
high intensity, resistance training and stress
Pancreas
- releases peptide hormones
Insulin
- secreted when BS levels are above normal
- produced by beta cells
- exercise dec insulin in blood and inc sensitivity of insulin
Glycogen
- catabolic action to inc BS and fatty acid in blood by glycogenolysis and lipolysis
- secreted when BS levels are below normal
- produced by alpha cells
Hormones that maintain glucose with endurance training
- epinephrine
- norepinephrine
- glucagon
- cortisol
Hormones that inc fatty acids with endurance training
- fatty acid and cortisol are opposite
- growth hormones
- epinephrine
- norepinephrine
Hormones that maintain fluid balance
- antidiuretic hormone
- aldosterone