Endocrine System Flashcards
Hormone Generic Timescale, Mechanism, Regulation
Timescale|| compared to neurotransmitter, slower, indirect, more long-lasting (time of effect: hours, days)
Mechanism|| released into general circulation and bind to specific receptors, found extra or intracellularly
Regulation|| if too much – downregulation of receptors ; if too little – upregulation of receptors
Endocrine v. Exocrine glands
Endocrine: release hormones into body fluids
Exocrine: release enzymes to external environment through ducts (ex. Sebaceous, sudoriferous, mucous glands)
Basic Hormone Types
- Peptide hormones
- Steroid hormones
- Tyrosine derivatives
Peptide Hormones (production)
Rough ER || preprohormone manufactured
ER lumen || cleavage of pre- portion into prohormone, sent to Golgi
Golgi || cleavage of pro portion of prohormone and addition of carbohydrate tail (some hormones), packaging into secretory vesicles
Secretory vesicles || release contents via exocytosis once they receive signal to do so
Peptide Hormones (characteristics)
- Water soluble, therefore hard time diffusing through effector cell membrane
- Bind to extracellular receptors that may act in various ways:
|| ligand gated ion channel or activate nearby channels
|| second messenger activates intracellularly cascade (via cAMP, cGMP, calmodulin) — this mechanism allows a small hormone concentration to have amplified effects
Effector
Target cell
Steroid Hormones (production and characteristics)
Production || synthesized in smooth ER and mitochondria, derived from (and similar to) cholesterol
Characteristics || lipid soluble | transport through blood requires being bound to protein | can diffuse through effector membrane, bind to cytosolic protein, and can go into nucleus to affect TRANSCRIPTION
Typical effect || increase specific cellular protein expression
Tyrosine Derivative Hormones
Thyroid Hormones || lipid soluble, transported through blood by plasma protein carriers to which they have high affinity (therefore slow release into effector tissue), affect transcription in large amount of tissue
Catecholamines (Epinephrine, Norepinephrine) || peptides, water soluble! bind to extracellular receptor and activate second messenger (usually cAMP)
Anterior Pituitary (location, regulation)
|| aka adenohypophysis
|| located beneath the hypothalamus
|| release or inhibition of hormone release controlled by hypothalamus, which is controlled by nervous system
Anterior Pituitary Hormones
- Human growth hormone (hGH)
- Adrenocorticotropin (ACTH)
- Thyroid stimulating hormone (TSH)
- Follicle stimulating hormone (FSH)
- Prolactin
- Leutenizing hormone (LH)
hGH (human growth hormone)
|| peptide, released by Anterior Pituitary
|| stimulates growth in nearly all tissue types by
Increasing rate of protein synthesis
Increasing cell size
Increasing frequency of mitosis
Increasing use of fatty acids for energy | decreasing use of glucose for energy
Increasing transport of amino acids across cell membrane
Increasing translation and transcription
TSH (thyroid stimulating hormone)
|| peptide hormone, released by Anterior Pituitary
|| stimulates thyroid:
Cell size
Rate of T3 and T4 secretion
Cell numberACTH (adrenocorticotropic hormone)
|| peptide, released by Anterior Pituitary
|| stimulates Adrenal Cortex release of glucocorticoids (stress response)
|| second messenger, via cAMP
Prolactin
|| peptide hormone, released by Anterior Pituitary
|| promotes lactation (milk production)
|| its release is Tonically inhibited by hypothalamus while progesterone and estrogen are present
Posterior pituitary (general)
|| aka neurohypophysis
|| hypothalamus synthesizes small polypeptides (ADH and oxytocin) and sends them to posterior pituitary through axons for release into blood
Oxytocin
|| small peptide, released by posterior pituitary
|| stimulates uterine contractions during pregnancy
|| stimulates milk ejection
ADH (anti diuretic hormone)
|| aka vasopressin
|| increase permeability of kidney collecting ducts to water –> increasing fluid reabsorption –> increasing blood pressure
|| coffee and beer are ADH blockers (therefore increase urine volume)
Adrenal cortex
|| outer portion of adrenal gland (that sits on top of the kidney)
|| secretes steroids once stimulated by peptide hormone ACTH
|| hormones:
Aldosterone (mineral corticoid)
Cortisol (glucocorticoid)
Small amount sex hormones
Aldosterone
|| mineral corticoid (steroid), secreted by Adrenal Cortex
|| acts at distal tubule and collecting duct (kidney)
|| increase Na and Cl reabsorption, increase K and H secretion
|| net plasma solute concentration increase! therefore increase BP
Gluconeogenesis
Formation of glucose and glycogen from amino acids, glycerol, lactic acid
In liver
Cortisol
|| glucocorticoid (steroid), secreted by adrenal cortex
|| stress response:
Increase blood glucose concentration (by liver gluconeogenesis)
Increase fatty acid use for energy
Decrease immune system ability to fight infection
May have anti inflammatory capability
Increases non hepatic protein degradation
Catecholamines (hormone)
|| tyrosine derivative, peptide hormones, secreted by adrenal medulla
|| norepinephrine, epinephrine
|| stress response, similar to sympathetic nervous system effects but longer lasting
| vasoconstriction for most internal organs and skin
| vasodilation (increased blood flow) for skeletal muscles
T3, T4
|| tyrosine derivatives, lipid soluble, secreted by thyroid gland
|| secretion regulated by TSH (from anterior pituitary)
|| slow release into effector tissue (high affinity to plasma protein carriers)
|| number stands for iodines bound
|| affects transcription, increase basal metabolic rate
Calcitonin
|| large peptide, secreted by thyroid gland
|| slightly decreases blood ca2+ by decreasing osteoclast activity and number
|| not super essential for blood ca regulation
