Physiology: Hormones in General Flashcards
(26 cards)
What is a endocrine?
secretes HORMONE, reach target organ via circulation
What hormones control digestion, utilization and storage? (glycogen, protein, fatty acids, glucose)
Cortisol GH/IGF-1 Glucagon Insulin Thyroid Hormone
What hormones control reproduction? (sexual, behavioral)
FSH/LH
Estrogen
Androgen
Prolactin
What hormones control growth and development? (cell proliferation, differentiation, skeletal and neuronal)
Estrogen Androgen GH/IGF-1 Vitamin D Cortisol Insulin/Glucagon
What hormones control the internal milieu? (body fluids, electrolytes, acid-base, glucose)
Insulin PTH ADH Cortisol Aldosterone
3 basic types of hormones:
Amino acid derived (epinephrine, thyroxine)
Steroids (progesterone)
Proteins and peptides (growth hormone, vasopressin)
Synthesis of protein and peptide hormones:
- synthesized through complex process of protein synthesis
- undergo further processing (pro hormone to hormone)
- exocytosis
- stored in secretory granules
- binds to specific binding proteins
Synthesis of steroid hormones:
- synthesized from acetate or cholesterol
- no storage
- spontaneous secretion
- binds to albumin and specific globulins
Synthesis of amino-acid hormones:
- synthesized from tyrosine and phenylalanine via enzymatic reactions
- stored in secretory granules
- exocytosis
- no binding protein (except thyroid hormone)
Measurement of Metabolic Clearance Rate
mg/ml plasma minute
To induce a cellular action a hormone must: (2)
- bind to specific cell surface or receptor
2. evoke hormone specific biological action
Why are hormone binding proteins not receptors?
They do not evoke a hormone-specific intracellular signal. Regulate free hormone levels in blood.
Protein hormone receptors:
cell membrane
Amine receptors:
cell membrane (exception thyroid hormone - nucleus)
Steroid receptors:
cytoplasm or nucleus
Responsiveness to hormone depends on:
- Hormone concentration
- Receptor number
- Duration of exposure
- Intervals between consecutive exposures
- Intracellular conditions, such as cofactors, enzymes, etc
- Concurrent presence of antagonistic or synergistic hormones
GPCR signaling via Protein Kinase A
- Hormone (1st messenger binds)
- Receptor activates G protein (GaS)
- G protein activates adenylate cyclase
- Adenylate cyclase converts ATP to cAMP (2nd messenger)
- cAMP activates protein kinases
Triggers response of target cell: activates enzymes, stimulates, cellular secretion, opens ion channel)
Hormones that act via cAMP
Epinephrine ACTH
FSH LH
Glucagon PTH
TSH Calcitonin
GPCR signaling via Protein Kinase C
- Hormone binds
- Receptor activates GaQ
- G protein activates PL-CB
- PLCB activates PIP2 to IP3 stimulating increase in Ca2+ and release of DAG
- Diacylglycerol (DAG) activates PKC
Steroid Hormone Action
- Steroid binding protein releases steroid hormone
- Hormone binds to receptor making hormone receptor complex
- Hormone receptor complex enters the nucleus binds to the hormone response element on the DNA to induce transcription
Negative Feedback
negatively influenced by the product of the target organ
Positive Feedback
positively influenced by the product of the target organ
Neuronal Feedback
release of hormones as the result of nerve activity (release of oxytocin from suckling)
Methods of detection: radioimmunoassay (RIA)
competition between radio labeled and unlabeled ligands for the antibody
HIGH SENSITIVITY, MORE SPECIFIC
