Hormones, Exercise, & Training Flashcards
What 3 components characterize the endocrine system
- host gland
- hormones
- target (receptor) cells or organs
What does the host gland do
- secrete hormones
- lack ducts but discharge their substances directly into the extracellular space around the gland
Describe hormones
- a chemical secreted by a cellar group of cells into the blood for transport to a distant target, where it exerts its effect at low concentrations
How can hormones be classified
- by their sources
- their receptor type
- their chemical structure
How do hormones function
- most hormones combine with a specific receptor molecule on the cell surface causing the cell to discharge a second chemical that initiates a cascade of cellular events
What are the 4 mechanisms that hormone actions occur
- changing the synthesis rate of intracellular proteins
- altering enzyme activity
- modifying cell membrane transport
- inducing secretory activity
What 3 factors determine a hormone’s plasma concentration
- sum of synthesis and release by the host gland
- rate of receptor tissue uptake
- rate of removal from the blood by the liver and kidneys
Describe growth hormone
- promotes cell division & proliferation throughout the body
How does growth hormone facilitate protein synthesis
- increasing amino acid transport through plasma membranes
- stimulating RNA formation
- activating cellular ribosomes that increase protein synthesis
Describe growth hormone relating to exercise
- secretion increases a few minutes after exercise begins
- relates more closely to peak exercise intensity rather than duration or total exercise volume
How is cortisol released
- hypothalamus secretes corticotropin-releasing hormone which is transported to the anterior pituitary & stimulates the release of corticotropin, which acts on the adrenal cortex to promote synthesis & release of cortisol
Describe ACTH related to exercise
- ACTH concentrations increase with exercise duration if intensity exceeds 25% of aerobic capacity
What are the two types of gonadotropic hormones
- follicle stimulating hormone (FSH)
- luteinizing hormone (LH)
What does follicle stimulating hormone (FSH) do in females
- initiates follicle growth in the ovaries & stimulates ovarian secretion of estrogens
What does follicle stimulating hormone and luteinizing hormone in combination do in females
- stimulates estrogen secretion & initiates rupture of the follicle to allow the ovum to pass through the fallopian tube for fertilization
What does follicle stimulating hormone do in males
- stimulates germinal epithelial growth in the testes to promote sperm development
What does luteinizing hormone do in males
- stimulates the testes to secrete the hormone testosterone
What hormones come from the anterior pituitary
- growth hormone
- corticotropin
- follicle stimulating hormone
- luteinizing hormone
What hormones come from the posterior pituitary
- antidiuretic hormone
- oxytocin
How does the posterior pituitary release hormones
- it does not synthesize its hormones, it receives them from the hypothalamus for release to the general circulation via neural stimulation
What does antidiuretic hormone do
- it limits how much urine the kidneys produce
What does oxytocin do
- it stimulates uterine muscle activity & milk ejection from the breasts during lactation