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Hormones
chemical messengers that regulate body functions
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What is the most common control mechanism for regulation?
negative feedback
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Up-regulation
the cell makes more hormone receptors
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Down-regulation
the cell makes less hormone receptors
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Hormone classifications
- based on structure
- peptides
- amines
- steroids
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Amino acids (amines)
- derived from Tyrisine
- secreted from thyroid and adrenal medulla
- stored as granules in the cytoplasm
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Proteins (peptides)
- majority of hormones
- water soluable
- excreted from pituitary, parathyroid, heart, stomach, liver, kidneys
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how are peptides stored?
as secretory granules until they are released into the blood
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Cholesterol (steroids)
- derived from cholesterol
- secreted by gonads, adrenal cortex and placenta
- once synthesized, passed directly into the bloodstream, they are not stored
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How hormones are elinated
- can be eliminated intact or inactivated
- can be taken up then destroyed
- can be destroyed in the liver and passed out in the bile
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What does the hypothalamus regulate?
temperature, hunger, mood, release of hormones, sex drive, sleep, thirst
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How to detect where hormone disorders are coming from
- tertiary - from the hypothalamus
- secondary - from the pituitary
- primary - from the gland
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How growth hormone is released
- released by anterior pituitary
- reacts to hypothalamus releasing growth hormone releasing hormone
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Growth hormones causes what?
an increase in size and number in cells
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Growth hormone is stimulated by
hypoglycemia, fasting, starvation, stress
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Growth hormone is inhibited by
Increased glucose levels, free fatty acid release, obesity, and cortisol
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Functions of growth hormone
⇧ bone length and thickness by depositing cartilage to the end of the bones
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sex hormones released in adolescence
causes bones to stop growing by replacing cartilage with calcium and phospahate
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IGF 1
stimulates protein synthesis and makes the body retain carbohydrates, blood glucose will rise
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IGF 1
⇩ adipose tissue, decreases glucose uptake in cells
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growth hormone causes
more protein uptake and synthesis, less glucose uptake, and an increase in fat breakdown
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Growth hormone deficiency
- idiopathic - lacks hypothalamic GHRH
- pituitary tumors/agenesis - can't produce GH
- Laron-type dwarfism - hereditary defect in IGF production
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four common dwarfism
- Achondroplasia
- Turner Syndrome
- Pituitary
- Lack of nurture
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Achondroplasia
- longs bones do not develop
- fibula become overly long
- head disproportionately large
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Achondroplasia
- can occur by itself with no prior family history
- risk increases with father's age
- can be an autosomal dominant trait
- most are spontaneous
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Turner's Syndrome
- Chromosomal abnormality, occurs only in females
- one X chromosome is either missing or defective
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Dwarfism
- GH deficiency
- body is in proportion
- can be treated with GH therapy
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Lack of Nurture
Failure to thrive
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