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What are chemical compounds secreted into the blood that affect target tissues generally at a site distant from original production?
Hormones
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Name the 3 classes of hormones
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What synthesizes steroid hormones?
- Adrenal glands
- Gonads
- Placenta
- Synthesized from cholesterol as needed, not stored, lipid soluble
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How are steroids circulated in the blood?
Need a carrier protein to circulate in the blood
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Name the clinically significant hormones
- Cortisol
- Aldosterone
- Testosterone
- Estrogen
- Progesterone
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How do steroid hormones work?
Free hormone is transported across cell membrane to interact with intracellular receptor
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How are steroids regulated?
Negative feedback by another hormone (cortisol/ACTH)
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What are protein hormones synthesized by?
- Anterior pituitary
- Placenta
- Pancreas
- Parathyroid glands
- Synthesized then stored in the cell as secretory granules until needed
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How are protein hormones carried in the blood?
- NO carrier needed
- Water soluble
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Name the clinically significant protein hormones
- Follicle stimulating hormone (FSH)
- Luteinizing hormone (LH)
- Thyroid stimulating hormone (TSH)
- Human chorionic gonadotrophin (hCG)
- Insulin
- Glucagon
- Parathyroid hormone
- Growth hormone
- Prolactin
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Name the glycoprotein hormones
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What are the glycoproteins (FSH, LH, TSH, and hCG) composed of?
- Alpha chains - identical
- Beta chains - unique for each hormone
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How do protein hormones work?
Protein hormones interact with a cell membrane receptor - which activates a second messenger system and then cellular action
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How is protein hormone synthesis regulated?
- Change in analyte concentration in serum
- Negative feedback by another hormone
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How are amine hormones synthesized?
- Synthesized by thyroid and adrenal glands
- Synthesized from amino acids
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How are amine hormones carried in the blood?
Some amine hormones require a carrier protein and others do not
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Name the clinically significant amine hormones
- Epinephrine
- Norepinephrine
- Thyroxine (T4)
- Triiodothyronine (T3)
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How do the amine hormones work?
- Epinephrine and norepinephrine do NOT bind to carrier proteins and interact with the receptor site on the cell membrane
- T4 and T3
circulate bound to carrier proteins, with the free hormone being transported across the cell membrane to interact with the intracellular receptor
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How are the amine hormones regulated?
- Regulated by nerve stimulation
- Another hormone
- Negative feedback
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Name the hormones produced by the hypothalamus
- Corticotropin releasing hormone (CRH)
- Gonadotropin releasing hormone (GnRH)
- Growth hormone releasing hormone (GHRH)
- Thyrotropin releasing hormone (TRH)
- Dopamine
- Somatostatin
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What hormone stimulates secretion of adrenocorticotropic hormone (ACTH)?
Corticotropin releasing hormone (CRH)
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What hormone stimulates secretion of follicle stimulating hormone (FSH) and luteinizing hormone (LH)?
Gonadotropin releasing hormone
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What hormone stimulates secretion of thyroid stimulating hormone (TSH) and prolactin?
Thyrotropin releasing hormone (TRH)
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What hormone inhibits prolactin release?
Dopamine
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What hormone inhibits secretion of TSH and GH?
Somatostatin
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Where does the antidiuretic hormone get produced?
Supraoptic and paraventricular nuclei of the hypothalamus
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What other names is the antidiuretic hormone (ADH) known by?
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Name the hormones secreted by the anterior pituitary
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What does an increase of cortisol level do?
Increased levels of cortisol turns off secretion of ACTH and CRH
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What does a decrease of cortisol level do?
Decreased levels of cortisol stimulates secretion of ACTH through negative feedback - which promote cortisol synthesis
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What else is the growth hormone known as?
Somatotropin
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What effect does the growth hormone have?
- Antagonistic effect to insulin in relationship the glucose metabolism
- Stimulates gluconeogenesis in the liver
- Stimulates lipolysis
- Promotes protein synthesis
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What is the reference range for growth hormone?
Basal level 2-5 ng/mL
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What is the clinical significance of increased levels of growth hormone?
- Pituitary gigantism
- Acromegaly (enlarged feet, hands, and facial bones...)
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What is the clinical significance of decreased levels of growth hormone?
- Adults - caused by pituitary adenomas or irradiation
- Children - may be familial or caused by a tumor, craniopharyngioma; results in pituitary dwarfism
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When is prolactin secreted and by what?
- Released upon stimulation from TRH
- Secreted by pituitary lactotroph cells
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What inhibits the release of prolactin?
Dopamine
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What hormone has the following functions:
-Initiates and maintains lactation
-Effects reproduction through ovarian and testicular steroidogenesis
-Affects the immune system
Prolactin
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What is the reference range for prolactin?
- Males: 3.0-14.7 ng/mL
- Females: 3.8-23.0 ng/mL
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What causes an increase of prolactin?
- Pituitary adenoma
- Trauma
- Inflammation
- Chronic renal failure
- Side effect of certain drugs
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Hyperprolactinemia results in __________
Hypogonadism
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What causes a decrease in prolactin?
Tumor that compresses or replaces normal pituitary tissue
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