ENDOCRINE SYSTEMENDOCRINE SYSTEM

ObjectivesObjectives Describe the functions of the endocrine glands Describe the functions of the endocrine glands

and there hormones.and there hormones. Describe the relationship between the Describe the relationship between the

hypothalmus and the pituitary glands. hypothalmus and the pituitary glands. Identify the diagnostic tests used to determine Identify the diagnostic tests used to determine

alterations in function in each of the endocrine alterations in function in each of the endocrine glands.glands.

Compare hyper/hypo pituitarism (thyroidism, Compare hyper/hypo pituitarism (thyroidism, parathyroidism, Addison’s, Cushing syndrome, parathyroidism, Addison’s, Cushing syndrome, gigantism, dwarfism, SIADH, diabetes insipidus), gigantism, dwarfism, SIADH, diabetes insipidus), causes, clinical manifestations, management and causes, clinical manifestations, management and nursing interventions. nursing interventions.

Identify teaching of patients needing steroid Identify teaching of patients needing steroid therapy.therapy.

Required ReadingRequired Reading

Smeltzer & Bare (2004) Chapter 42Smeltzer & Bare (2004) Chapter 42 Readings on reserve: Unit IV Readings on reserve: Unit IV

Endocrine Endocrine http://arbl.cvmbs.colostate.edu/hboohttp://arbl.cvmbs.colostate.edu/hboo

ks/pathphys/endocrine/index.htmlks/pathphys/endocrine/index.html ( Excellent web-site) ( Excellent web-site)

Endocrine SystemEndocrine System

The endocrine system (The endocrine system (endo, endo, within) is within) is comprised of glands that secrete comprised of glands that secrete hormones that are carried by the hormones that are carried by the blood to act on target tissue, blood to act on target tissue, regulating multiple body processes. regulating multiple body processes. (ductless)(ductless)

The endocrine, nervous and immune The endocrine, nervous and immune system work together to create a system work together to create a precise control over all body organs precise control over all body organs and metabolic processes. and metabolic processes.

HormonesHormones

Defined as chemical substances Defined as chemical substances synthesized and secreted by a synthesized and secreted by a specific organ or tissue, carried by specific organ or tissue, carried by the blood stream to other cells or the blood stream to other cells or organs, to produce a particularl organs, to produce a particularl regulatory effect.regulatory effect.

(Lewis, Heitkemper & Dirksen, 2004)(Lewis, Heitkemper & Dirksen, 2004)

Principal functions of the Principal functions of the endocrine systemendocrine system

Maintenance of the internal environment Maintenance of the internal environment in the body (maintaining the optimum in the body (maintaining the optimum biochemical environment).biochemical environment).

Integration and regulation of growth and Integration and regulation of growth and development.development.

Control, maintenance and instigation of Control, maintenance and instigation of sexual reproduction, including sexual reproduction, including gametogenesis, coitus, fertilization, fetal gametogenesis, coitus, fertilization, fetal growth and development and nourishment growth and development and nourishment of the newborn. of the newborn.

The Endocrine & Nervous SystemThe Endocrine & Nervous System

The effects of hormones secreted by The effects of hormones secreted by the endocrine system affect the the endocrine system affect the nervous system and are in turn nervous system and are in turn mediated by the nervous system.mediated by the nervous system.

Example: adrenal medulla secretes Example: adrenal medulla secretes substances – epinephrine & substances – epinephrine & norepinephrine – that act as neuro norepinephrine – that act as neuro transmitters causing an effect of the transmitters causing an effect of the sympathetic nervous system.sympathetic nervous system.

Nervous systemNervous system

The nervous system exerts point-to-point control through nerves, similar to sending messages by conventional telephone. Nervous control is electrical in nature and fast.

Hormones travel via the Hormones travel via the bloodstream to target cellsbloodstream to target cells

•The endocrine system sends its hormonal messages to essentially all cells by secretion into blood and extracellular fluid. Like a radio broadcast, it requires a receiver to get the message - in the case of endocrine messages, cells must bear a receptor for the hormone being broadcast in order to respond.

Endocrine System & Immune Endocrine System & Immune SystemSystem

There is also close There is also close interaction between interaction between the endocrine and the endocrine and immune systems.immune systems.

Example: Example: Glucocorticoids play Glucocorticoids play a major role in the a major role in the body’s response to body’s response to stress. stress.

PRINCIPAL ENDOCRINE PRINCIPAL ENDOCRINE GLANDSGLANDS

PituitaryPituitary AdrenalAdrenal ThyroidThyroid Parathyroid GlandsParathyroid Glands PancreasPancreas Gonads (ovaries & testes)Gonads (ovaries & testes)

(Hypothalamus link b/t nervous & endocrine (Hypothalamus link b/t nervous & endocrine systems)systems)

Endocrine Glands GlandsEndocrine Glands Glands

Pineal gland Pineal gland Secretes Secretes melatonin, a hormone that melatonin, a hormone that helps regulate wake-sleep helps regulate wake-sleep cycle.cycle.

HypothalmusHypothalmus:: primary link primary link btw. the endocrine and nervous btw. the endocrine and nervous system. It controls the release system. It controls the release of pituitary hormones.of pituitary hormones.

Pituitary (anterior & Pituitary (anterior & posterior):posterior): the “master gland the “master gland b/c of its importance.b/c of its importance.

ThyroidThyroid: Causes increase in : Causes increase in metabolic rate, increase in metabolic rate, increase in protein and bone turnover.protein and bone turnover.

ParathyroidsParathyroids: (4) regulate : (4) regulate serum calcium & phosphate.serum calcium & phosphate.

ThymusThymus: Secretes hormones that : Secretes hormones that maintain and contribute to the maintain and contribute to the production of peripheral t-cell population. production of peripheral t-cell population.

Adrenal glandsAdrenal glands (cortex & medulla) (cortex & medulla) Cortex secretes glucocorticoids (cortisol), Cortex secretes glucocorticoids (cortisol), mineralcorticoids (aldosterone) and mineralcorticoids (aldosterone) and androgens.Medulla secretes substances androgens.Medulla secretes substances that act as neurotransmitters on that act as neurotransmitters on sympathetic nervous system. sympathetic nervous system.

PancreasPancreas: endocrine and exocrine : endocrine and exocrine functions Endocrine functions carried out functions Endocrine functions carried out by the Islets of Langerhan which produce by the Islets of Langerhan which produce insulin and glucagon (regulate blood insulin and glucagon (regulate blood glucose levels). Exocrine cells secrete glucose levels). Exocrine cells secrete digestive enzymes into the small digestive enzymes into the small intestine.intestine.

GonadsGonads – female ovaries in abdomen; – female ovaries in abdomen; male- testes in scrotummale- testes in scrotum

Other Structures Producing Other Structures Producing HormonesHormones

•Glands within the gastro-intestinal tract

•Structures within the heart and blood vessels (atrial natriuretic peptide/factor (ANF or ANP)

•Kidney: renin & erythropietin

A cell is a target for a hormone because is A cell is a target for a hormone because is has a specific receptor for that hormonehas a specific receptor for that hormone

Most hormones circulate in blood, coming into contact with essentially all cells. However, a given hormone usually affects only a limited number of cells, which are called target cells. A target cell responds to a hormone because it bears receptors for the hormone.

Hormones -Three classes based on Hormones -Three classes based on structurestructure

1.1. SteroidSteroid

2.2. Peptide (protein)Peptide (protein)

3.3. AminesAmines

Mechanism of Protein Hormone Mechanism of Protein Hormone

• Are water soluble

• Bind to cell membrane receptors on target tissue and activate second messenger within.

•Rapid response time

Peptide (Protein) HormonesPeptide (Protein) Hormones

Steroid HormonesSteroid Hormones Steroid hormones Steroid hormones

pass through the the plasma plasma membrane & do membrane & do not require an not require an external external receptor.receptor.

Hormones exert their actions in four Hormones exert their actions in four ways:ways:

1. Maintenance of 1. Maintenance of internal internal environmentenvironment

2. Regulation of 2. Regulation of energy availabilityenergy availability

3. Reproduction3. Reproduction

4. Growth & 4. Growth & developmentdevelopment

1.1. Maintenance of internal environment Maintenance of internal environment is done through such activities as:is done through such activities as:

• Control of extracellular fluid Control of extracellular fluid volume & BPvolume & BP

• Electrolyte regulationElectrolyte regulation• Maintenance of bone, muscle Maintenance of bone, muscle

& fat stores& fat stores

2. Regulation of energy available2. Regulation of energy available

Control of the conversion of Control of the conversion of calories to energycalories to energy

Storage of energyStorage of energy Mobilization of energy stores Mobilization of energy stores

when neededwhen needed

3. Reproduction3. Reproduction

Ovaries: Ovaries: produce ova produce ova and hormones and hormones estrogen estrogen & progesterone& progesterone & are & are controlled by pituitary. controlled by pituitary.

Testes: Testes: produce the produce the male reproductive cells male reproductive cells spermatozoa and the spermatozoa and the male hormones male hormones testosterone and inhibintestosterone and inhibin

44. . Growth and DevelopmentGrowth and Development

Anterior pituitary secretes Anterior pituitary secretes growth hormonegrowth hormone

Review PedsReview Peds

Feedback ControlFeedback Control

Hormone concentration in the blood Hormone concentration in the blood stream is maintained at a fairly stream is maintained at a fairly constant level. When hormone levels constant level. When hormone levels rise, further production of the rise, further production of the hormones is inhibited. When the hormones is inhibited. When the hormone level drops, the rate of hormone level drops, the rate of production increases.production increases.

Feedback controlFeedback control Negative feedback is most common. The Negative feedback is most common. The

gland itself responds by increasing or gland itself responds by increasing or decreasing hormone levels based on decreasing hormone levels based on feedback from various factors. feedback from various factors.

Positive feedback is less common: The Positive feedback is less common: The increased activity of hormone production increased activity of hormone production and response stimulates further and response stimulates further production.production.

The regulation of hormone levels The regulation of hormone levels depend mainly on the body’s negative depend mainly on the body’s negative

feedback system. For example:feedback system. For example:

Elevated blood sugar levels stimulate the Elevated blood sugar levels stimulate the release of insulin from the pancreas. release of insulin from the pancreas.

The insulin facilitates the transfer of sugar The insulin facilitates the transfer of sugar from the blood to the cellsfrom the blood to the cells

Low BS inhibits the release of more insulinLow BS inhibits the release of more insulin Negative feedback is the corrective actionNegative feedback is the corrective action

Feedback Control of Hormone Feedback Control of Hormone ProductionProduction

Feedback loops are used extensively to regulate secretion of hormones in the hypothalamic-pituitary axis. An important example of a negative feedback loop is seen in control of thyroid hormone secretion

Positive FeedbackPositive Feedback

The regulation of hormone levels The regulation of hormone levels also depend on the body’s also depend on the body’s positivepositive feedback systemfeedback system

Positive feedback systems amplify Positive feedback systems amplify changes rather than reversing themchanges rather than reversing them

For example: During labour, For example: During labour, muscle contractions becomes muscle contractions becomes stronger & stronger under the stronger & stronger under the influence of oxytocininfluence of oxytocin

Diseases of the endocrine system Diseases of the endocrine system are related to either:are related to either:

an an excess or a deficiencyexcess or a deficiency of a of a specific hormone orspecific hormone or

to a deficit in the receptor site.to a deficit in the receptor site.

The thyroid and testes are the only The thyroid and testes are the only glands that can be examined directlyglands that can be examined directly

Knowledge of A&P together Knowledge of A&P together with with data from the data from the

history & history & lab tests are essential lab tests are essential in in assessing the assessing the endocrine endocrine system.system.

Hypo and Hypersecretion of Hypo and Hypersecretion of HormonesHormones

Hyper-secretion is production of Hyper-secretion is production of too much hormonetoo much hormone

Hypo-secretion is production of Hypo-secretion is production of too little hormonetoo little hormone

Endocrine Disorders & Psychiatric Endocrine Disorders & Psychiatric DisturbancesDisturbances

GlandGland HypoHypo HyperHyper

PituitaryPituitary MyxedemaMyxedema

DwarfismDwarfism

Sex DysfunctionSex Dysfunction

Diabetes InsipidusDiabetes Insipidus

GigantismGigantism

AcromegalyAcromegaly

Sexual DysfunctionSexual Dysfunction

ThyroidThyroid CretinismCretinism

MyxedemaMyxedemaGravesGraves

ParathyroidParathyroid TetanyTetany Hypercalcemia Hypercalcemia

AdrenalAdrenal Addison’s DiseaseAddison’s Disease Cushing DiseaseCushing Disease

HyperaldosteronismHyperaldosteronism

PancreasPancreas Diabetes MellitusDiabetes Mellitus HypoglcemiaHypoglcemia

Endocrine disorders may be Endocrine disorders may be associated with a wide range of associated with a wide range of psychological/psychiatric symptoms psychological/psychiatric symptoms such as depression, mania, paranoid such as depression, mania, paranoid disorders, cognitive disturbances, disorders, cognitive disturbances, hostility, & irritability. hostility, & irritability.

Nurses need to be aware that such Nurses need to be aware that such symptoms symptoms may precedemay precede other other manifestations of an endocrine manifestations of an endocrine disorder and/disorder and/or be early indications or be early indications of its relapse.of its relapse.

Endocrine Disorders Commonly Manifesting Endocrine Disorders Commonly Manifesting

Psychiatric CharacteristicsPsychiatric Characteristics

Cushing’s DiseaseCushing’s Disease Addison’s DiseaseAddison’s Disease HyperthyroidismHyperthyroidism HypothyroidismHypothyroidism HyperprolactinaemiaHyperprolactinaemia HyperparathyroidismHyperparathyroidism

Hypothalamus and Pituitary as Hypothalamus and Pituitary as PartnersPartners

HYPOTHALMUSHYPOTHALMUS

Coordinates the Coordinates the working of the working of the autonomic nervous autonomic nervous system & endocrine system & endocrine system. Receives info system. Receives info from cerebral from cerebral hemisphere, brain hemisphere, brain stem, spinal cord, stem, spinal cord, autonomic & autonomic & peripheral nerves, peripheral nerves, sensessenses..

Hypothalamus FunctionHypothalamus Function

Produces regulatory hormones that Produces regulatory hormones that stimulate the anterior pituitary stimulate the anterior pituitary (especially stimulating or inhibiting): (especially stimulating or inhibiting): TRH, GHRH, GnRH, GH-IH, CRH, PRH, TRH, GHRH, GnRH, GH-IH, CRH, PRH, PIHPIH

Ultimately the hypothalamus can Ultimately the hypothalamus can controlcontrol every endocrine gland in the every endocrine gland in the body!body!

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Hypothalamic HormonesHypothalamic Hormones

Releasing Factor Anterior Pituitary Target CellsReleasing Factor Anterior Pituitary Target Cells

TRHTRH TSH TSH thyroid thyroid

GHRH GHGHRH GH bone muscle bone muscle

GH-IH GH bone muscleGH-IH GH bone muscle

GnRHGnRH FSH, LH FSH, LH ovaries, testes ovaries, testes

CRHCRH ACTH ACTH Adrenal cortex Adrenal cortex

PRH ProlactinPRH Prolactin mammary glands mammary glands

PIH (dopamine inhibitor) PIH (dopamine inhibitor)

HYPOTHALMUS: SOME MAJOR HYPOTHALMUS: SOME MAJOR FUNCTIONSFUNCTIONS

Autonomic nervous systemAutonomic nervous system Secretion of pituitary hormonesSecretion of pituitary hormones Organization of body metabolismOrganization of body metabolism Availability of energy foods such as Availability of energy foods such as

glucoseglucose sleep & wakefulnesssleep & wakefulness Temperature, thirst & water Temperature, thirst & water

regulationregulation Hunger & AppetiteHunger & Appetite Behavior - fear, rage, sexual desireBehavior - fear, rage, sexual desire GrowthGrowth Sexual reproductionSexual reproduction

Hypothalamus Pituitary Hypothalamus Pituitary PartnersPartners

Due to the unique interaction Due to the unique interaction between the hypothalamus and the between the hypothalamus and the pituitary gland, pituitary gland, hypothalamic hypothalamic dysfunction is often associated dysfunction is often associated with alterations in pituitary with alterations in pituitary function.function. Because the hypothalamus Because the hypothalamus is also responsible for many is also responsible for many homeostatic regulatory functions, homeostatic regulatory functions, alterations can also occur in behavior, alterations can also occur in behavior, temperature control &, appetite. temperature control &, appetite. •Assess

Hypothalmus: disturbance in function may be triggered by:

•Mental or emotional upset, grief

& worry

•Weight changes (drastic)

•Other causes - tumors,

•cerebral infections, trauma.