Upload
mabel-cooper
View
216
Download
1
Tags:
Embed Size (px)
Citation preview
Endocrine SystemEndocrine SystemDr Khamis Al HashmiDr Khamis Al Hashmi
Department of physiologyDepartment of physiologyRoom # 006Room # 006
Ext. 3435Ext. 3435Email: [email protected]: [email protected]
11
Nervous Vs Endocrine system
Nervous and endocrine systems acts Nervous and endocrine systems acts together to coordinate functions of body together to coordinate functions of body system. system.
Nervous system releases; Nervous system releases; NeurotransmitorsNeurotransmitors
Endocrine system releases; Endocrine system releases; HormonesHormones
22
Nervous Vs Endocrine system (cont.)
Characteristic Nervous system Endocrine system
Mediators molecules
Neurotransmitters Hormones
Site of mediator action
Close to site of release
Far from site of release
Types of target cells Muscle cells, gland cells, other neurons
Cells throughout the body
Time to onset of action
Within milliseconds
Seconds to hours
Duration of action Briefer (milliseconds)
Longer (seconds to days) 33
Endocrine Vs Exocrine glands
Exocrine gland:Exocrine gland: secrete their products into secrete their products into ducts that carry the secretion into body ducts that carry the secretion into body cavities, into lumen of organs, or to the outer cavities, into lumen of organs, or to the outer surface of the body.surface of the body.
E.g. Sweat, sebaceous, mucus, digestive E.g. Sweat, sebaceous, mucus, digestive glands.glands.
Endocrine glands:Endocrine glands: secrete their products into secrete their products into the interstitial fluid surrounding the secretory the interstitial fluid surrounding the secretory cells diffused into blood capillaries cells diffused into blood capillaries carried to target cells.carried to target cells.
44
Definitions
Hormone: Hormone: is a mediator molecule that is released in is a mediator molecule that is released in
one part of the body but regulates activity of cells in one part of the body but regulates activity of cells in
other parts of the body.other parts of the body.
Target cell: Target cell: A cells whose activity is affected by aA cells whose activity is affected by a
particular hormone.particular hormone.
Receptor:Receptor: A specific molecule or cluster of moleculesA specific molecule or cluster of molecules
that recognizes and binds a particular ligand (hormone) that recognizes and binds a particular ligand (hormone)
55
Circulating hormones Vs Local hormones
A) Circulating hormones
66
B) Local hormones:
1) Paracrines
E.g. Nitric oxide.
IL2 77
2) Autocrines
E.g. IL2
Local hormones usually are inactivated quickly 88
Chemical classes of hormonesChemical classes of hormones
a) Water-soluble hormones: Amine hormones Amine hormones (Retain an amino group (Retain an amino group
(NH(NH33++))
Peptide and protein hormonesPeptide and protein hormones Eicosanoid hormones Eicosanoid hormones (derived from (derived from
arachidonic acid. Eg. Prostaglandins, leukotrienes)arachidonic acid. Eg. Prostaglandins, leukotrienes)
b) Lipid-soluble hormones: Steroid hormonesSteroid hormones Thyroid hormonesThyroid hormones Nitric oxideNitric oxide
99
a) Water soluble hormone
1010
b) Lipid soluble hormone
1111
Hormone transport in the blood
Water soluble hormones circulate in a Water soluble hormones circulate in a free form (free form (UnUnbound).bound).
Lipid soluble hormones bound to Lipid soluble hormones bound to transport proteins. (>90%).transport proteins. (>90%).
Importance:Importance:- Increase the solubility in blood.Increase the solubility in blood.- Slow the rate of excretion by kidney or Slow the rate of excretion by kidney or
degradation by liver.degradation by liver.- Provide a ready reserve of hormone. Provide a ready reserve of hormone.
1212
Responsiveness of a target cell to a hormonedepend on:
1) Concentration of the hormone2) Number of receptors3) Influence by other hormone (hormones interaction)
1) Concentration of the hormone
– The hormone’s rate of secretion (all hormones)
– Rate of metabolic inactivation and excretion (all hormones)
– Rate of metabolic activation (few hormones)
– Extent of binding to plasma protein (lipophilic hormones)
1313
Control of hormone secretion Important to prevent overproduction or
underproduction
Three types of signals:1. Signals from the nervous systemEg. Nerve impulse to adrenal medulla Epinephrine
2. Chemical changes in the blood.Eg. Blood Ca2+ level parathyroid hormone
3. Other hormoneEg. Ant. Pituitary hormones hormones of other
glands 1414
Negative-feedback control control
Short loop feedback
long loop feedback1515
Positive-feedback control
1616
Diurnal (circadian) rhythm The secretion rate of many hormones rhythmically The secretion rate of many hormones rhythmically
fluctuate up and down as function of time.fluctuate up and down as function of time.– Diurnal (or circadian),Diurnal (or circadian), i.e. “day-night”. characterised i.e. “day-night”. characterised
by repetitive oscillations in hormone levels that are by repetitive oscillations in hormone levels that are very regular and have a frequency of one cycle every very regular and have a frequency of one cycle every 24 hours24 hours.. Eg. Cortisol secretion. Eg. Cortisol secretion.
– Other rhythmOther rhythm. Monthly menstrual period.. Monthly menstrual period.
Negative feedback control mechanisms operate toNegative feedback control mechanisms operate to
maintain whatever set point is established for that time.maintain whatever set point is established for that time.
1717
Clearance of hormones from the bloodClearance of hormones from the blood– Metabolic destruction by the tissuesMetabolic destruction by the tissues
– Binding with the tissues.Binding with the tissues.
– Excretion by the liver into the bile.Excretion by the liver into the bile.
– Excretion by the kidneys into urine. Excretion by the kidneys into urine.
1818
2) Number of receptors
Down regulation:Down regulation:A hormone present in excess Receptors
– Destruction of the receptor by lysosomesDestruction of the receptor by lysosomes– Decrease production of receptors Decrease production of receptors – Inactivation of some of the receptor moleculesInactivation of some of the receptor molecules– Inactivation of some of the intracellular signaling moleculesInactivation of some of the intracellular signaling molecules– Temporary sequestration of the receptor to the inside of the Temporary sequestration of the receptor to the inside of the
cell.cell.
Up regulation:Up regulation:A hormone is deficient Receptors
1919
3) Hormones interaction:3) Hormones interaction:
Permissiveness (permissive effect):Permissiveness (permissive effect): powerful action of a powerful action of ahormone on target cells require a simultaneous or recenthormone on target cells require a simultaneous or recentexposure to a second hormone.exposure to a second hormone.Eg. Epinephrine and thyroid hormones in lipolysis. Eg. Epinephrine and thyroid hormones in lipolysis.
Synergism (synergistic effect): Synergism (synergistic effect): the effect of two hormonesthe effect of two hormonesacting together is greater or more extensive than the effect ofacting together is greater or more extensive than the effect ofeach hormone acting alone.each hormone acting alone.Eg. FSH and estrogen for normal development of oocytes in Eg. FSH and estrogen for normal development of oocytes in ovaries.ovaries.
Antagonism (antagonistic effect):Antagonism (antagonistic effect): one hormone opposes the one hormone opposes theaction of another hormone. action of another hormone. Eg. Insulin and glucagon.Eg. Insulin and glucagon.
2020
Endocrine dysfunctionEndocrine dysfunction
a) Decrease in hormone activity Decrease in hormone secretion by the
endocrine gland (hyposecretion). Increase removal of the hormone from the
blood Abnormal tissue responsiveness to the
hormone:- Lack of target cell receptors. Lack of an enzyme essential to the target cell
response
2121
b) Increase in hormone activity Increase in hormone secretion by the Increase in hormone secretion by the
endocrine gland (hypersecretion)endocrine gland (hypersecretion) Reduced plasma protein binding of the Reduced plasma protein binding of the
hormone (too much free, biologically active hormone (too much free, biologically active hormonehormone
Decreased removal of the hormone from the Decreased removal of the hormone from the blood:-blood:-
Decreased inactivation.Decreased inactivation. Decreased excretionDecreased excretion
2222
Location of endocrine glandsLocation of endocrine glandsOrgan Hormones secreted
Hypothalamus Releasing and inhibitory hormones (e.g. thyrotropin releasing hormones, growth hormone inhibitory hormone), ADH, oxytocin.
Anterior pituitary gland Tropic hormones: ACTH, TSH LH,FSH), GH, prolactin.
Posterior pituitary gland Oxytocin, ADH (vasopressin)
Thyroid gland Thyroxine, Tri- iodothyronine.
Adrenal gland Mineralocorticoids (e.g. aldosterone), glucocorticoids (e.g. cortisol), catecholamines (e.g. epinephrine, nor-epinephrine).
Parathyroid glands Parathyroid hormone.
Pancreatic Islets Insulin, glucagon.
Gonads Testosterone, estradiol.
2323
Hypothalamus and pituitary glandHypothalamus and pituitary gland
Anterior pituitary
Hypothalamic-Hypophyseal portal system
2424
Posterior Pituitary
Hypothalamohypophyseal tract
2525
HypothalamusHypothalamus
HormonesHormones Target cells Target cells Major functionMajor function
Releasing hormones:Releasing hormones:
TRH, CTR, GnRH, GHRH, TRH, CTR, GnRH, GHRH, PRHPRH
Anterior pituitaryAnterior pituitary Stimulate release of Stimulate release of particular anterior particular anterior pituitary hormone.pituitary hormone.
Inhibiting hormones:Inhibiting hormones:
GHIH, PIHGHIH, PIHAnterior pituitaryAnterior pituitary inhibit release of inhibit release of
particular anterior particular anterior pituitary hormone.pituitary hormone.
2626
Anterior pituitary glandAnterior pituitary glandHormonesHormones Target cells Target cells Major functionMajor functionThyroid stimulating hormone (TSH)Thyroid stimulating hormone (TSH) Thyroid follicular cellsThyroid follicular cells Stimulates TStimulates T33 and T and T44 secretion secretion
Adrenocorticotropic hormone (ACTH)Adrenocorticotropic hormone (ACTH) Zona fasciculata and reticularis Zona fasciculata and reticularis of adrenal cortexof adrenal cortex
Stimulates cortisol secretionStimulates cortisol secretion
Growth hormone (GH)Growth hormone (GH) Bone; soft tissueBone; soft tissue
LiverLiver
Essential for growthEssential for growth
Metabolic effects; protein Metabolic effects; protein metabolism, fat mobilization and metabolism, fat mobilization and glucose conservationglucose conservation
Stimulates IGF secresionStimulates IGF secresion
Follicle-stimulating hormone (FSH)Follicle-stimulating hormone (FSH) Female: ovarian folliclesFemale: ovarian follicles
Males: Seminiferous tubules in Males: Seminiferous tubules in testestestes
Promote follicular growth and Promote follicular growth and development; stimulates estrogen development; stimulates estrogen secretionsecretion
Stimulates sperm productionStimulates sperm production
Luteinizing hormoneLuteinizing hormone Females: ovarian follicle and Females: ovarian follicle and corpus luteumcorpus luteum
Males: inerstitial cells of leydig Males: inerstitial cells of leydig in testes in testes
Stimulates ovulation, corpus luteum Stimulates ovulation, corpus luteum development, estrogen and development, estrogen and progesterone secresionprogesterone secresion
Stimulates testosterone secretionStimulates testosterone secretion
ProlactinProlactin Females: mammary glands Females: mammary glands (breast)(breast)
MalesMales
Promotes breast development; Promotes breast development; stimulates milk secresionstimulates milk secresion
UncertainUncertain 2727
Posterior pituitaryPosterior pituitary
HormonesHormones Target cells Target cells Major functionMajor function
Antidiuretic hormone Antidiuretic hormone (ADH), Vasopressin (ADH), Vasopressin
Kidney tubulesKidney tubules
ArteriolesArterioles
Increase water Increase water reabsorptionreabsorption
Produces Produces vasoconstrictionvasoconstriction
OxytocinOxytocin UterusUterus
Mammary glands Mammary glands (Breast)(Breast)
Increase contractilityIncrease contractility
Causes milk ejectionCauses milk ejection
2828
Thyroid GlandThyroid GlandHormonesHormones Target cells Target cells Major functionMajor functionTetraiodothyronine (TTetraiodothyronine (T44 or or thyroxin); Tri-thyroxin); Tri-iodothyronine (Tiodothyronine (T33))
Most cellsMost cells Increase metabolic Increase metabolic rate; essential for rate; essential for normal growth and normal growth and nerve developmentnerve development
CalcitoninCalcitonin BoneBone Decrease plasma Decrease plasma calcium concentrationcalcium concentration
Parathyroid GlandParathyroid GlandHormonesHormones Target cells Target cells Major functionMajor function
Parathyroid hormone Parathyroid hormone (PTH)(PTH)
Bone, kidneys, intestine.Bone, kidneys, intestine. Increases plasma Increases plasma calcium concentration; calcium concentration; decrease plasma decrease plasma phosphate concentration; phosphate concentration; stimulates vitamin D stimulates vitamin D activationactivation 2929
Adrenal glandAdrenal glandHormonesHormones Target cells Target cells Major functionMajor function
Cortex:Cortex:
Zona Zona glomerulosaglomerulosa
Zona Fasiculata Zona Fasiculata and reticularisand reticularis
Mineralocorticoid Mineralocorticoid (Aldosterone)(Aldosterone)
Glucocorticoid Glucocorticoid (cortisol)(cortisol)
AndrogensAndrogens
Kidney tubulesKidney tubules
Most cellsMost cells
Female: bone Female: bone and brainand brain
Increases NaIncreases Na++ reabsorptionand Kreabsorptionand K++ excresionexcresion
Increases blood Increases blood glucose at the glucose at the expense of protein expense of protein and fat store; and fat store; contributes to contributes to stress adaptationstress adaptation
Pubertal growth Pubertal growth spurt and sex drivespurt and sex drive
MedullaMedulla Epinephrine and Epinephrine and norepinephrinenorepinephrine
Sympathetic Sympathetic receptor site receptor site throughout the throughout the bodybody
Contributes to Contributes to stress adaptation stress adaptation and blood pressure and blood pressure regulation regulation
3030
Pancreas (Islets of langerhans)Pancreas (Islets of langerhans)
HormonesHormones Target cells Target cells Major functionMajor function
Beta (Beta (ββ) cells) cells
Alpha (Alpha (αα) cells) cells
D cellsD cells
InsulineInsuline
GlucagonGlucagon
SomatostatinSomatostatin
Most cellsMost cells
Most cellsMost cells
Digestive Digestive systemsystem
Pancreatic islet Pancreatic islet cellscells
Promotes cellular Promotes cellular uptake, use and uptake, use and storage of storage of absorbed nutrientsabsorbed nutrients
Important for Important for maintain nutrient maintain nutrient levels in blood levels in blood during during postabsorptive postabsorptive state state
Inhibits digestion Inhibits digestion and absorption of and absorption of nutrientsnutrients
Inhibits secretion Inhibits secretion of all pancreatic of all pancreatic hormoneshormones
3131
OvariesOvaries
HormonesHormones Target cells Target cells Major functionMajor functionEstrogenEstrogen Female sex organs; Female sex organs;
body as whole.body as whole.
BoneBone
Promotes follicular Promotes follicular development, development, development of development of secondary secondary characteristics, characteristics, stimulate uterine and stimulate uterine and breast growth.breast growth.
Promotes closer of Promotes closer of epiphyseal plateepiphyseal plate
ProgesteroneProgesterone UterusUterus Prepare for pregnancyPrepare for pregnancy
3232
TestesTestes
HormonesHormones Target cells Target cells Major functionMajor function
TestosteroneTestosterone Male sex organs; body Male sex organs; body as wholeas whole
Stimulate sperm Stimulate sperm production; production; development of development of secondary secondary characteristics; characteristics; Promotes sex drivePromotes sex drive
Testes and ovaries secret inhibin that acts on the anterior Testes and ovaries secret inhibin that acts on the anterior pituitary to inhibit secretion of follicle stimulating hormonepituitary to inhibit secretion of follicle stimulating hormone. .
3333