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26 Cards in this Set
- Front
- Back
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What are the 3 types of regulation in the body?
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Nervous:
-electrochemical signals Humoral: -send chemical signals, release into body fluids Endocrine: -part of humoral -endocrine system: all hormone-secreting glands, tissues and cells -endocrine gland: ductless gland that secrete hormones directly into ECF |
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What are types of chemical messengers?
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hormones:
-specialized endocrine cells/tissues/organs -act on distant target cells Neurohormones: -secreted by neurons in ECF Paracrine agents: -secreted by specialized or nonspecialized endocrine cells -rapidly taken up, destroyed or immobilized --> short-time effects Autocrine agents: -secreted by cell into ECF and bind to surface receptors of own cell |
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What are some biological functions of hormones?
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embryogenesis
physical, sexual, and mental growth and development reproduction metabolism and energy balance circadian rhythms immunity maintaining of homeostasis |
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What are some functional characteristics of hormones?
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high biological activity
long latent period of action specificity of action multiple action multiple control |
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What are differences between endocrine and exocrine glands?
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endocrine:
-ductless -intracellular effects (ex. intracellular metabolism) -synthesize and release hormones into interstitial fluid -small amt of secretion exocrine: -have ducts that carry secretions to body surface, body cavity or lumen of another organ -extracellular effects (ex. food digestion) -large amount of secretion |
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What are the Primary and Secondary Endocrine organs?
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Primary:
-Hypothalamus -Pancreas -Gonads -Placenta in pregnant female -pituitary gland -pineal gland -thyroid/parathyroid gland -thymus -adrenal gland Secondary: -heart -LIver -Stomach -Small Intestine -Kidney -Skin |
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What is a candidate hormone?
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hormones with inconclusive functions (ex. melatonin in humans)
local hormones (paracrine and autocrine agents) |
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What are some classifications of Hormones?
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Steroids - ALL DERIVED FROM CHOLESTEROL
Amino Acid derivatives/amines -Tyrosine - thyroxine & catecholamines -Tryptophan - melatonin and seratonin -Histidine - Histamine Peptides (oxytocin, ADH) and proteins (insulin, glucagon) Derivatives of FA (arachidonic acid) -elcosanoids: (prostaglandins and prostacyclins), leukotrienes, and lipoxines Gases (NO) |
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What are the route of administration for hormones?
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steroids and thyroid hormones are not digested in GI and can cross intestinal lining --> administered orally
Peptides and proteins digested by GI --> given by injection (ex. Insulin for diabetics) |
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What is the life cycle of hormones?
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secretion
synthesis and storage --> release --> transport in a circulatory fluid --> intracellular action --> either biological effect or inactivation and excretion |
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How are water soluble and lipid soluble hormones transported in blood?
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Water Soluble and some lipid soluble:
-dissolved in plasma (unbound form) --> biological action Lipid soluble hormones, thyroid hormones etc: -bound to plasma protein -Low affinity, high binding = albumins and prealbumins -High affinity, low binding = globulins -this leads to low clearance rate, high water solubility and concentration in blood, low speed of biological action -acts as a physiological reserve |
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What are Hormone receptors (def, location, function)?
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Definition:
-hormone receptors: glycoprotein molecules with specific ligand binding sites -ligand: any molecule or ion which binds to a binding site by forces other than covalent bonds location: -polypeptide hormones and catecholamines: plasma membrane receptors on target cells -steroid and thyroid hormones, vit D, prostaglandins, retinoic acid - specific nuclear/cytoplasmic receptors Functions: -recognition of a particular hormone -receptor-effector coupling: transition of hormone recognition to intracellular response (signal transduction) |
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How are receptors regulated?
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Down regulation:
-endocytosis of receptors and subsequent intracellular metabolic degradation -lower production of receptors -inactivation of receptors this lowers target cells sensitivity to a hormone (ex. when plasma concentration of a hormone is high) Up Regulation: -increase in number of receptos -increase sensitivity of target cells of hormone (ex. when plasma concentration of hormone is too low) |
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What are the differences in the mechanism of hormone action between fat and water soluble?
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water soluble:
-receptors on surface of target cell membrane -involved in cascading chemical reactions, second messenger, and protein kinases Fat Soluble: -receptors inside target cell in cytoplasm or nucleus -hormone receptor complex binds to DNA to regulate gene expression by influencing TRANSCRIPTION |
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What is the signal transduction pathway? (INCOMPLETE)
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Ligand + Receptor --> allosterical modulation which activates receptor
Intracellular receptors: -ONLY modulation of gene transcription Plasma membrane receptors: - |
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What are Second Messengers?
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hormones are first messengers
needed for water soluble hormones because they bind to plasma membrane activated by first messenger serve as chemical relays from plasma membrane to intracellular biochemical machinery one hormone can trigger generation of many secondary messengers ex. is G protein, one molecule leads to phosphorylation of millions of proteins |
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What are G-Protein Coupled Receptors?
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largest family of plasma membrane receptors
heterotrimetric - contain 3 subunits (alpha, beta, and gamma) GTP binding complex binds GDP and GTP and hydrolyzed GTP interacts with various effector proteins (ex. adenylyl cyclase) |
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How is protein phosphorylation/dephosphorylation catalyzed?
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phosphorylation:
-catalyzed by protein kinases dephosphorylation: -catalyzed by phosphoprotein phosphotase (PP) |
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What is the action of Lipophilic Hormones?
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bind to intracellular receptors in:
cytoplasm - gluco and mineralocorticoids nucleus - sex steroids, thyroid hormones, vit D, active metabolites, retinoic acid |
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What are factors for responsiveness of target tissues to hormones?
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concentration of unbound hormone in plasma
number of hormone receptors in target tissues influences exerted by other hormones |
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How do horomones act synergistically?
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Additive:
-net effect of 2 or more hormones equals sum of individual effects ex. adrenaline and noradrenaline act synergistically to increase HR Complementary: -net effect of 2 or more hormones greater than sum of individual effects ex. milk production requires prolactin, oxytocin, estrogen, cortisol follicular growth requires FSH and estrogen Agonism: -can initiate maximal biological response (full agonism) or submaximal response (partial agonism) |
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What is Antagonism and Permissive effect?
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Antagonism:
-physiological: insulin promotes glycogen synthesis in liver, glucagon does opposite) -competitive: binds to particular type of receptors -noncompetitive: blocks at some point the chain of events Permissive effect: -Estrogen stimulates formation of progesterone in uterus which leads to increase uterus response to progesterone -PTH stimulates production of hydroxylating enzymes converting Vit D3 to active metabolites |
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What are the types of control of Hormone Secretion?
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Neural:
-adrenergic, cholinergic etc hormone-hormone feedback chemical feedback chronotropic inputs (circadian rhythms, sleep-wake cycle) |
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What are examples of Negative/Positive Feedback?
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Negative:
-Thyroid hormone with TSH Positive: -oxytocin during childbirth |
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What are long, short, and ultra short loops?
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long:
-operate between controlle variable and endocrine or neuroendocrine cells Short: -operates between anterior pituitary and hypothalamus ultrashort: -operates within HT |
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What Hormones are released by each Primary Endocrine organ?
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Hypothalamus:
-TRH, CRH, GnRH, Somatostatin, Dopamine Anterior Pituitary: -TSH, FSH, LH, prolactin, GH, ACTH, MSH Posterior Pituitary: -Oxytocin and ADH (Vasopressin) Thyroid: -Calcitonin and T3, T4 Parathyroid: -PTH Pancreas: -Insulin, Glucagon Adrenal Medulla: -Epinephrine and Norepinephrine Kidney: -Renin Adrenal Cortex: -Cortisol, Aldosterone, Adrenal Androgens Testes: -Testosterone Ovaries: -Estradiol and Progesterone Corpus Luteum: -Estradiol and Progesterone Placenta: -HcG, HPL, Estriol and Progesterone |
