Endocrine Flashcards
endocrinology
- study of hormones
- chem that go thruought the body
hormones are responsible for what?
- long term ongoing fxns of the body
- metabolism (thyroid)
- regulation of the internal environment as a homeostasis
- reproduction
- growth
- development
hormones act in 3 basic ways
- (1) Rates of enzymatic reactions (speeds up rxn)
- (2) Transport of ions or molecules across cell membranes
- (3) Gene expression and protein synthesis (Ex: growth hormone)
cellular mechanism of action for hormones
- depends on binding to target cell receptors
- initiates biochemical responses
hormone action must be terminated
- half-life indicates length of activity
- measure how long molecules can degrade
most hormones are what
- peptides or proteins
peptide hormone synthesis, storage, and release
– Preprohormone is a large, inactive precursor
– Prohormone is processed to smaller form but still inactive
– Active hormone stored in vesicle; requires signal to be released
transported in the blood and half-life of peptide hormones
- relatively short half-life
cellular mechanism of action of peptide hormones
– Bind surface membrane receptors
– Cellular response through signal transduction system
steroids hormones are derived from cholesterol
- Made only in a few organs
– Adrenal cortex of adrenal gland and gonads - Steroid hormone synthesis and release
– Made as needed, not stored - Transport in the blood and half-life of steroid hormones
– Bind carrier proteins in blood
– Longer half-life (example: cortisol = 69-90 minutes in blood) - Cellular mechanism of action of steroid hormones
– Cytoplasmic or nuclear receptors stimulate genomic effects
– Cell membrane receptors stimulate nongenomic repsonses
some hormones are derived from single amino acid
- Derived from tryptophan
– Melatonin from pineal gland - Derived from tyrosine
– Single tyrosine give rise to catecholamines
▪ Epinephrine, norepinephrine, and dopamine
▪ Behave like peptide hormones
– Two tyrosine molecules give rise to thyroid hormones
▪ Behave like steroid hormones
stimulating hormones come from what?
anterior pituitary gland
inhibiting or releasing comes from what?
hypothalamus
anterior pituitary gland hormones
- thyroid stimulating hormones (TSH)
- luitenizing hormone (LH)
- follicle stimulating hormone (FSH)
- growth hormone (GH)
- prolactin (lactation)
- ACTH = adrenocortical tropic hormone (gets released when you’re stressed. goes to adrenocortex to release cortisol)
primary, secondary, teritary
- primary: think actual gland itself
- secondary: think pituitary gland
- tertiary: think hypothalamus
posterior pituitary gland
- anti-diuretic (vasopressin)
- oxytocin (milk outlet and stimulates pos feedback loop in birthing)
reflex pathways have similar components
– Stimulus, sensor, input signal, integration, output signal, one or more targets, & response
the endocrine cell is the sensor in simple endocrine reflexes
- parathyroid hormone (PTH)
many endocrine reflexes involve the what?
nervous system
neurohormones are secreted into the blood by what?
neurons
the posterior pituitary stores and releases two neurohormones
– Neural tissue
– Stores hormones produced in the hypothalamus
– When hypothalamus is stimulated, posterior pituitary secretes two
neurohormones: vasopressin (antidiuretic hormone (ADH) and oxytocin
the anterior pituitary secretes six hormones
– Epithelial origin, thus true endocrine gland
– Trophic hormones stimulate secretion of other hormones
– Prolactin (PRL), thyrotropin (TSH), adrenocorticotropin (ACTH), growth hormone (GH), follicle-stimulating hormone (FSH), and luteinizing hormone (LH)
– Regulated by hypothalamic hormones
▪ Somatostatin (SS) = growth hormone-inhibiting hormone
portal systems
- encapsulation of veins
- consists of two sets of capillaries connected in series by a vein
hypothalamic-hypophyseal (pituitary) portal system
– Hypothalamic neurons produce trophic hormones
– Released into 1st capillary bed in portal system to anterior pituitary
– Anterior pituitary endocrine cells produce trophic hormones
– Released into 2nd capillary bed in portal system to target tissues
what does the portal system connect?
- hypothalamus and anterior pituitary