Physiology > Endocrine System > Flashcards

Endocrine System Flashcards

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1
Q

what does the endocrine system include

A

-all endocrine cells and tissues that produce hormones or paracrine
-endocrine organs are scattered throughout the body
-endocrine cells and tissues produce about 30 different hormones
-hormones control and coordinate body processes

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2
Q

where do endocrine cells release secretions

A

-into extracellular fluid
-exocrine cells do not release into extracellular fluid

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3
Q

endocrine organs and tissues of the head and neck

A
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4
Q

endocrine cells and tissues of the trunk

A
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5
Q

mechanisms of intercellular communication

A

-direct
-paracrine
-autocrine
-endocrine

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6
Q

direct communication

A

-excahneg of ions and molecules between adjacent cells across gap junction
-occrs between two cells of the same type
-highly specialized and relatively rare

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7
Q

autocrine communication

A

-messages affect the same cells that secrete them
-chemicals involves are autocrines
e.g: prostaglandins secreted secreted by smooth muscle cells cause the same cells to contract

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8
Q

endocrine communication

A

-endocrine cells release hormones that are trasnported in bloodstream
-alters metabolic activities of many organs

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9
Q

target cells

A

have receptors needed to bind and read hormonal messages

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10
Q

hormones

A

-changes types, quantities or activities of enzymes and proteins in target cells
-can alter metabolic activites of multiple tissues and organs at the same time
-affect long term processes like growth and development

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11
Q

similarities between endocrine and nervous system

A

-rely on release of chemicals that bind to specific receptors on target cells
-share many chemical messengers
-are regulated mainly by negative feedback
-function to preserve homeostasis by coordinating and regulating activities

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12
Q

classes of hormones table

A
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13
Q

amino acid derivatives

A

-small molecules
-related to AA
-derivatives of tyrosine include thyroid hormones, and caecholamins like epi, norepi, and dopamine
-derivatives of tryptophan include serotonin and melatonin

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14
Q

peptide hormones

A

-chains of AA
-most are inactive converted to active hormones before or after they are secreted (prohormones)
-glycoproteins = >200 AA and have carbohydrate side chains (TSH, LH, FSH)
-short polypeptides and small proteins are ADH and OXT (9AA)
-small proteins include insulin, GH, Prolactin
-all hormones secreted by hypothalamus, heart, thymus, GI, pancreas, posterior pit,

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15
Q

Lipid derivatives

A

-eicosanoids
-steroid hormonez

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16
Q

eicosanoids

A

-derived from arachidonic acid (20C FA)
-paracrines that coordinate cell activities and affect enzyme activity
-some eicosanoids act as hormones as well
-prostglands coordinate local cellular activities

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17
Q

steroid hormones

A

-include: androgens, esteogens and progesterone, corticosteroids, calcitriol
-bound to specific transport proteins in the plasma and remain in criculation longer than peptide hormones

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18
Q

catecholamines and peptide hormones

A

-not lipid solible
-cannot penetrate plasma membrane
-bind to receptor proteins on outer surfacee of plasma membrane

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19
Q

notes abotu steroid and thyroid hormones

A

-lipid soluble
-diffuse across plasma membrane and bind to receptors inside cell

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20
Q

free hormones

A

-remain functional for less than an hour and are inactivated when they:
-diffuse out of bloodstream and bind to target
-are absorbed or broken down by liver or kidneys
-are broken down by enzymes

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21
Q

thyroid and steorid hormones transport and activation

A

-remain functional much longer
-more than 99% become attached to special transport proteins in blood
-equilibirum state exists between free and bound forms
-bloodstream contains substantial reserve of bound hormones

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22
Q

binding of hormone may:

A

-alter genetic activity
-alter rate of protein synthesis
-change membrane permeability

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23
Q

hormone receptor

A

-a protein molecule to which a particular molecule binds strongly
-different tissues have different combinations of receptors
-presence or absence of specific receptor determines hormonal sensitivity of cell

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24
Q

down regulation

A

-presence of hormone triggers decrease in the number of hormone receptors
-when levels of a particular hormone are high, cells become less sensitive to it

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25
up-regulation
-absence of hormone triggers increase in the number of hormone receptors -when levels of a particular hormone are low, cells become more sensitive to it
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first messenger
-hormone that binds to extracellular receptor -promotes release of second messenger
27
second messenger
-inteermediary molecule that appears due to hormone receptor interaction -may act as enzyme activator, inhibitor or cofactor -results in change rates of metabolic reactions -e.g cAMP, cGMP, Ca2+
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G proteins and second messengers photo
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steps in increasing cAMP level, which accelerates metabolic activity of cell
1. activated G protein activates adenylate cyclase 2. adenylate cyclase converts ATP to cyclic AM 3.cyclic amb functions as a second messenger 4, generally cyclic AMP activates kinases hat phosphorylates protein -
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enzyme that converts cAMP to AMP
-phosphodiesterase -acts quickly - increased cAMP levels short lived
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G proteins and calcium ions
-G protein activates phospholipase C (PLC) -triggers receptor cascade beginning with production of DAG and Inositol triphosphase (IP3) from phospholipids -IP3 diffuses into cytoplasm and triggers release of CA2+ from intracellular reserves -calcium ion channels open due to activation of protein kinase C and CA enters cell -Ca binds to calmodulin
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hormones and intracellular receptors
-steroid hormones can alter rate of DNA transcripstion in nucleus -alterations in synthesis of enymes or structural protein directly affect activity and strucutre of target cell -thyroid hormones bind to receptors within nucleus and on mitochondria activationg genes or changing rate of trasncription, increasing rate of ATP production
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steroid hormones photo
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thyroid hormones photo
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hormone secretion
-mainly controlled by negative feedback -can be triggered by: humoral stimuli, hormonal stimuli, or nueral stimuli
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humoral stimuli
-change in extracellular fluid
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control of hormone secretion
-may involve only one hormone -humoral stimuli controls hormone secretion by heart, pancreas, parathyroid gland and GI -hormonal stimuli may involve one or more intermediary steps and have two or hore hormones involved -nueral stimuli
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Orientation and anatomy of the pit gland photo
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blood supply to pit gland photo
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the hypothalamus
-regulates functions of the pituitary gland -synthesises ADH and OXT and transports them to posterior pit for release -secretes regulatory hormones that control secretory activity of anterior pit -contains autonomic centers that exert control over adrenal medulla
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releasing hormones diagram
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5 hormones of anterior pit
-TSH -ACTH -PRL -GH /somatotropin -Gonadotropins
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gonadotropins
-FSH -LH -GnRH
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hypogonadism
caused by low production of gonadotropins
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LH functions
-in females induces ovulation and stimulates secretion of estrogens and progesteron -males stimulates production of androgens
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hormones diagram
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PIH and PRL interaction photo
48
growth hormone stimulates
-liver cells to release somatomedins that stimulate tissue growth -stem cells in epithelia and connectibe tissues to divide -breakdown of triglycerides in adipocytes which leads to glucose sparingn effect -break down of glycogen by liver cells. causing diabetogenic effect
49
somatomedins
-cause skeletal muscle fibers and other cells to increase uptake of AA
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production of growth hormone refulated by
-growth hormone releasing hormone -growth hormone inhibiting hormone
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pars intermedia
-secretes melanocyte stimulating hormone -virtually nonfunction in adults excpeti in pregnant women and those with certain diseases
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posterior lobe of pit gland
-called nuerohyphysis -contains unmyelinated axons of hypothalamic nuerons -supra-optic manufactures ADH -paraventricular nuclei manufactures OXT
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oxytocin
-stimulates contraction of uterus during labour -promotes ejection of milk after delivery
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thyroid gland
-lies inferior to thyroid cartilage of larynx -two lobes connected by isthmus -c cells or parafollicular cells
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thyroid follicles
-hollow spheres lined by cuboidal epithelium -surrounded by capillaries -cells absorb iodied ions from blood -follicle cavity contains viscous colloid
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thyroglobulin
globular potein synthesized by follicle cells -secretes into colloid of thyroid follicle -contains tyrosine
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two thyroid hormones
-thyroxine contains four idoine atoms -triiodothyronine contains three idoine atoms
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thyroid gland photo
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syntehsis storage and secretion of steorid hormones
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homeostasis of t3 and t4 concentration
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thyroid hormones effects
-elevate oxygen and energy consumption -may cause rise in temp in children -increase HR and force of contraction -increase sensitivity to sympathetic stimulation -maintain normal sensitivity of respiratory centers to [O2] and [CO2] -stimulate red blood cell formation -stimulate activity in other endocrine tissues -accelerate turnover of minerals in bone
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where do thyroid hormones bind
-in cytoplasm -on surfaces of mitochondria -in nucleus
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why are thyroid hormones essential in children
-essential to normal development of skeletal muscualr and nevrous system
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C cells
-thyroid -produce calcitonin
65
calcitonin
-helps regulate concentration of Ca2+ in body fluids -stimulates Ca2+ excretion by kidneys -prevents Ca2+ abdosrption by digestive tract
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thryoid hormones involvement in glycolysis and ATP production
-results in calorgenic effect - increased energy consumption and heat generation of cells -responsible for strong immediate, and short lived increased rate of cellular metabolism
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parathyroid glands
-two pairs -embedded in posterior surface of thyroid gland -all four glands together weigh 1.6g
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parathyroid hormone
-secretes by paraythroid (principle) cells in response to low concentrations of Ca2+ in blood -antagonist for calcitonin -stimulates osteoclasts (turnover of bone, Ca2+ release) -enhances reabsorption of Ca2+ by kidneys reuding urine losses -stimulates formation and secretion of calcitrol by kidneys
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homeostasis of blood calcium photo (increased blood ca)
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homeostasis of blood calcium (decreased blood ca)
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superifical adrenal cortex
-storage of lipids especially cholesterol and fatty acids -manufactures steroid hormones
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inner adrenal medulla
-secretory activities controlled by sympathetic division of AND -produces epi and norepi (catecholamines)
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adrenal cortex
-subdivided into three zones -outer z. glometulosa, middle zona fasiculata, inner zona reticularis
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zona glomerulosa
-outer region of cortex -produces aldosterone
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aldosterone
-stimulates conservation of sodium ions and elimation of potassium ions -increases sensitivity of salt receptors in taste buds -secreted in response to drop in blood sodium, blood volume, or blood pressure, rise in blood K
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zona fasiculata
-produces glucocorticoids (cortisol, corticosterone, cortisone)
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glucocorticoids have inhibitory effect on production of
-corticotropin-releasing hormone in hypothalamus -ACTH in anterior pituitary
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zona reticularis
-branching network of endocrine cells -forms narrow band bordering each adrenal medulla -produces small quantities of androgens under stimulation by ACTH some converted to estrogens, and they stimulate the devvelopment of pubic hair before puberty
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adrenal medulla
-two types of secretory cells: one producing epi (75-80% secretion), other produces norepinephrine (20-24%)
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results of activation of adrenal medulla
-in skeletal muscles, E and NE trigger mobilization of glycogen reserves and accelerate breakdown of glucose -in adipose tissue, stored fats are broken down into fatty acids -in the liver, glycogen molecules are broken down -in heart stimulation of B1 receptors speeds and strengthens cardiac muscle contraction
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adrenal hormones chart
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pineal gland
-lies in posterior portion of roof of third ventricle -contains pinealocytes that synthesize melatonin
83
functions of melatonin
-influence circadian rhymthms -inhibit repro functions -protect against damage by free radicals
84
exocrine pancreas
-consists of clusters of gland cells called pancreatic acini and their attached ducts -takes up 99% of pancreatic volume -gland and duct cells secrete alkaline enzyme rich fluid to go to the digestive tract
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endocrine pacreas
-consists of pancreatic islets: -alpha cells produce glucagon -beta cells produce insulin -delata cells produce peptide hormone identicle to GH-IH -pancreatic polypeptide cells produce pancreatic polypeptide
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flucutation of blood glucose results
-beta cells secrete insulin stimulating transport of glucose into target cells -when blood glucose level decreases alpha cells secrete glucagon stimulating glycogen breakdown. and glucose release by liver
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increased blood glucose photo
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decreased blood glucose level photo
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insulin
-peptide hormone released by beta cells -accelerate glucose uptake -accelerate glucose use and enhance ATP production -stimulate glycogen formation -stimulate AA absorbtion and protein synthesis -stimulate triglyceride formation in adipocytes
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glucagon
-released by alpha cells -mobilizes energy reserves -stimulate breakdown of glycogen in skeletal muscle fibers adn liver cells -stimulate breakdwon of triglycerides in adipocytes -stimulate production and release of glucose in liver cellsh
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hyperglycemia
-abnormally high glucose levels in blood
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diabetes mellitus
-high glucose concentration that overwhelm reabsorbtion capibilities of kidneys -glucose in urine -polycuria - high urine volume
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type I diabetes mellitus
-inadequate insulin produced by beta cells -patients require daily injectiosn or continous infusion of insulin -5% of cases -children and young adults
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type II diabetes mellitus
-most common -usually normal amounts of insulin are produced at least initially and tissues develop resistance -associated with obesity -weight loss effective treatment
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complications of untreated or poorly managed diabetes mellitus
-kidney degenration -retinal damage (diabetic retinopathy) -early heart attacks -peripheral nerve problems (diabetic neuropathies) -peripheral tissue damage due to reduced blood flow
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intestines secondary endocrine functuon
-release hormones that coordinate digestive activities
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kidney secondary endocrine function
-release the hormones calcitriol and eryhtropoietin -release renin
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renin
-converts angiotensin to angiotensin I -in lungs angiotensin converting enzyme. onverts angiotensinI to angiotensin II
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production of calcitriol photo
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decreasing blood pressure and volume homesostatic mech
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secondary endocrine function of heart
-production of ANP and BNP -blood volume becomes excessive -actions oppose angiotensin II -results in lower blood volume and pressure
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secondary endocrine function of thymys
-thymosin -promote development and maturation of lymphocytes
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secondary endocrine function of adipose tissue
-leptin -feedback control of appetite -maintains normal levels of GnRH and gonadotropin synthesis
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secondary endocrine function of testes
-androgens by intersitial endocrine cells -nurse/sertoli cells secrete inhibin and support sperm
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secondary endocrine function of ovaries
-estrogens -follicle cells reorganize into CL and release estrogens and progesterone
106
four outcomes when cell recieves instructions from two hormones at same time
-antagonistic effect - result depends on balance between two hormones -synergistic effect - additive effect -permissive effect - one hormone is needed for another to produce effect -integrative effect - hormones produce different but complementary result
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hormones important to growth
-growth hormone -thyroid hormone -insulin -PTH -calctriol -repro hormones
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growth hormone in children and in adults
-child: muscular and skeletal developmetn -adult: maintain blood glucose concetration, movilize lipid reserve
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result of thyroid hormone absent during fetal development or dor first year after birth
-nervous system failure to develop -development delay results -if T4 concentration decline before puberty normal skeletal development does not continue
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insulin in growth
allows passgae of glucose and AA across plasma membrane -important for growing cells
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PTH and calcitriol in growth
promote absorbtion of calcium salts from bloodstream for deposition in bone -inadequate levels result in weak flexible bones
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reproductive hormones in growth
-stimulate growth and differentiation in target tissues -produce gender differences in skelton and secondary sex characteristics
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stress
-any condition that threatens homeostasis
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general adaptation syndrome
-stress response -how body responds to stress causing factors three phases: alarm, resistance, exhaustion
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alarm phase oef GAS
-immesdiate response -symapthetic division of AND -energy reserves are mobilized -body prepares for fight or flight -epinephrine is domiannt
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resistant phase of GAS
-stress longer than few hours -weeks or months -glucocrticoids are dominant -lipids and AA are mobilized for energy -glucose is conserved for use for nervous tissue
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exhaustion phase of GAS
-begins when homeostatic regulation breaks down -drop in K levels due to aldosteron produce in resistance phaw -failure of one or more organ systems will be fatal
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hormone changes can effect
-behaviour -intellectual capacilities -memory -learning -emotional states
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age relatd wchanges
-repro hormones decline in concentration -some endocrine tissues become less responsive to stimulation
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