Structure Structure and and

Function of Function of Endocrine Endocrine

SystemSystem1

2

•Name the parts of the endocrine system and discuss the function of each part•Discriminate the functions of each endocrine hormone secreted by same endocrine glands •Analyze the action of each hormone and demonstrate its contribution in maintaining homeostasis•Classify hormones according to its molecular structure and actions

Identify and describe the structure and function of important biochemical compounds, including protein and steroid hormones (314-3)

Analyze homeostatic phenomena to identify the feedback mechanisms involved (317-2)

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•Regulates many bodily functions

•Maintains homeostasis by regulating the production of chemicals that affect most functions of the body

•Secretes substances that aid the nervous system

•Important regulator of growth and development

•Endocrine glands are ductless glands, unlike exocrine glands that secrete substances into ducts.

The Endocrine System

Maintaining homeostasisMaintaining homeostasis

high

low

hormone 1

lowersbody condition

hormone 2

gland

specific body condition

raisesbody condition

gland

Feedback

Negative FeedbackNegative FeedbackResponse to changed body

condition◦if body is high or low from normal level

signal tells body to make changes that will bring body back to normal level

◦once body is back to normal level, signal is turned off

high

hormone 1

lowersbody condition

gland

specific body condition

RegulationRegulation

How we maintain homeostasis◦nervous system

nerve signals control body functions

◦endocrine system hormones chemical signals control body functions

HormonesHormonesWhy are hormones needed?

◦chemical messages from one body part to cells in other parts of body

◦communication needed to coordinate whole body

◦maintaining homeostasis

growth hormones

Endocrine SystemEndocrine SystemEndocrine system releases

hormones◦glands which secrete (release) chemical signals into blood chemicals cause changes

in other parts of body growth hormones sex hormones response hormones metabolism hormones and more….

Responding to hormonesResponding to hormonesLock and key system

◦hormone fits receptor on “target” cell

targetcell

non-targetcells

secretingcell

can’treadsignal

can’treadsignal

II. Endocrine System vs Neuronal II. Endocrine System vs Neuronal SystemSystem1. Neural & Hormonal communication

a. Similarities i. Chemicals are stored and released ii. Release of chemicals is due to stimulation iii. Many different hormones & neurotransmitters iv. Both systems react w/specific receptors

v. Second messenger involved in both (The first messenger reacts to the initial signal - like an

ionotropic receptor, found in CNS only)

2. Second messenger reacts to a signal from a first messenger (like a

metabotropic receptor) and affects

intracellular functioning; it is a complex intracellular response

that affects functioning.

b. Differences i. In nervous system, neurons communicate with adjacent neurons; in hormones messages are sent long distances ii. Neural messages induce rapid response compared to hormones which have slower messages iii. Neural messages follow the all or none principle; hormonal messages are graded in strength iv. Neural messages can be directed as observed in behavior; hormonal messages are primarily involuntary (cannot be directed)

2. Three types of hormonesa. Protein hormones – effect is on receptors within the membrane, binds to the receptors on the outside of membrane; its effects are the most rapid of all the hormones i. Oxytocin – involved in development of relationships ii. Adrenocorticotrophin – protein hormone; chains of amino acids

b. Amine hormones – same relatively fast receptor response as protein hormones i. Epinepherine ii. Norepinepherine iii. Thyroid hormones iv. Melatonin

c. Steroid hormones – binds to the intercellular receptors; slow actions i. Gonadal hormones

1. Estrogen, progesterone, androgens ii. Adrenal hormones

1. Glucocorticoids, mineralocorticoids

Major Glands of the Major Glands of the Endocrine SystemEndocrine System

HypothalamusPituitaryThyroidAdrenalGonads: Ovaries & Testes

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Consists of:

glands secrete

hormones

intobloodstream

to

target tissues

The Endocrine System

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Homeostasis exists when there is a balance of substances. Endocrine conditions are due to either hypo (too little) or hyper (too much) secretions of substances (hormones).

hyper

hypo

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Hypothalamus

•Part of the nervous system. Also serves as an endocrine gland because it releases hormones that regulate pituitary hormones

•Hormones released have either a releasing or an inhibiting factor

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Pineal Gland

•Located superior and posterior to the pituitary gland

•Releases melatonin, a hormone believed to affect sleep and gonad functioning

PituitaryPituitaryAnterior Pituitary - derived during embryological

development from the roof of the mouth

- connected to the hypothalamus by a portal system (hypothalamic-pituitary portal system)

- most of the hormones are released from the anterior pituitary

Posterior Pituitary - derived from nervous tissue - two protein hormones released: oxytocin

& vasopressin _________________________________

Two Important Points:Hormones released from the posterior

pituitary are synthesized in the hypothalamus.

Hormones released from the anterior pituitary are dormant unless directed to be released by the hypothalamus via Releasing Factors.

Hypothalamus

Anterior Pituitary Posterior Pituitary

Target Organs Target Organs

RF

SH

Hormone

Hormone

RF = Releasing Factor SH = Stimulating Hormone

Pituitary & all Hormones are Under the Control of the Hypothalamus

Hypothalamic Hormones:

Gondotropin RFCorticotropin RF (CRF) Thyrotropin

RFGrowth Hor RF

Prolactin RF

Pituitary Hormones:

Follicle SH &

Luteinizing Hor.

Thyrotropin SHAdrenocorticoptropin Hormone (ACTH)

ProlactinGrowth Hormone

Target Gland or Structure:

Ovaries & Testes

(androgens, estrogen)

Adrenal Gland

(cortisol)

Cells of bodyThyroid Gland

(thyroxine)

Bones, breasts & cells of body

Adrenal GlandAdrenal Gland

i. Adrenal cortex (outer) produces about 50 different chemicals including…1. Mineralocorticoids (outer layer)2. Glucocorticoids, cortisol (middle layer)3. Sex hormones (inner most layer)

a. Estrogen, progesterone androgens note: Congenital adrenal hyperplasia – too much

testosterone produced by mother. This comes from dysfunction in adrenal gland.

ii. Adrenal medulla (inner)1. Dopamine Norepinepherine/Epinepherine

Thyroid GlandThyroid Gland

1. Too little thyroxin – hypothyroidism a. Depression (clinical or subclinical), attention & memory problems2. Too much thyroxin – hyperthyroidism a. Agitation, irritability, & weight loss

*Goiters – Growths on thyroid gland

Gonads & Hormones

LH & FSH

Growth HormoneGrowth HormoneCells of body in response to growth

hormonei. During childhood GH is at maximum

1. Too little and we have a small person

2. Too much and we have gigantism, often accompanied by

acromegaly (continued growth of extremities of bones)

a. Makes hands, feet, jaw, nose, and eye sockets (orbits) enlarged

OxytocinOxytocinThe hormone involved in

inducing labor during childbirthHormone involved in bondingHormone involved in

relationshipsMight be deficient in Autism

All hormones utilize feedback loops:Autocrine response – Same as the autoreceptors, both communicate and terminate release

Note similarity to the CNS: Autoreceptors – in the CNS the

receptors on presynaptic cell that are sensitive to its own NT

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Parathyroid Gland•Four oval shaped glands located on the dorsal side of the thyroid•Regulates calcium and phosphate levels

Thymus Gland•Also part of the immune system•The hormones secreted stimulate the production of T and B cells

Adrenal Glands•A pair of glands, each one situated on top of a kidney•Each gland has an outer portion (adrenal cortex) and inner portion (adrenal medulla)•Regulates electrolytes•Adrenal medulla secretes catecholamines (epinephrine and norepinephrine) in response to stress

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•Helps maintain proper blood glucose levels•Is both an endocrine and exocrine gland. The islets of Langerhans serve its endocrine functions•Two types of cells, alpha and beta are produced by the islets of Langerhans

Insulin is released by the beta cells which stimulate the glucose to be sent to the body’s cells and convert unused glucose to glycogen

Low

Blood sugar

Glucagon is released by the alpha cells which stimulate stored glycogen to be transformed into glucose again

Blood sugar

Elevated

Pancreas

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Insulin and Glucagon Insulin

Glucagon

Artery

Drop in blood glucose stimulates glucagon

secretion

Rise in blood glucose stimulates insulin secretion

Promotes movementof glucose into certain cellsStimulates formationof glycogen from glucose

In response to insulin, blood glucose drops toward normal (and inhibits insulin secretion)

In response to glucagon,blood glucose risestoward normal (andinhibits insulin secretion)

Stimulates cells to break downglycogen into glucoseStimulates cells to convertnon-carbohydrates into glucose

Pancreas

Ultimately,what controls the Ultimately,what controls the endocrine system?endocrine system?

Our emotionsOur perceptionsOur cognitionsOur experiencesOur behaviorOur response to the environment

Higher Brain Areas

Hypothalamus

Pituitary

Endocrine Glands

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Ovaries Testes

•Located in the female pelvic region one attached to the top of each fallopian tube

•Produce the female hormones:

-estrogen-progesterone

•Located in the scrotum, a sac outside the body

•Produce spermatozoa which fertilizes the female ova

•Produce male sex hormones:

-testosterone

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Combining Form Meaning

aden(o)

adren(o)

gluc(o)

glyc(o)

gonad(o)

pancreat(o)

parathyroid(o)

thyr(o)

gland

adrenal glands

glucose

glycogen

sex glands

pancreas

parathyroid

thyroid gland

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Abbreviation Meaning

ACTH

ADH

CRH

DM

FSH

GH

GTT

HCG

adrenocorticotropic hormone

antidiuretic hormone

corticotropin-releasing hormone

diabetes mellitus

follicle-stimulating hormone

growth hormone

glucose tolerance test

human chorionic gonadotropin

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Abbreviation Meaning

IDDM

LH

MSH

NIDDM

PRL

PTH

STH

TSH

insulin-dependent diabetes mellitus

luteinizing hormone

melanocyte-stimulating hormone

noninsulin dependent diabetesmellitus

prolactin

parathyroid hormone, parathormone

somatotropin hormone

thyroid-stimulating hormone