endocrin system

7/28/2019 Endocrin System

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The Endocrine System

AP Chapter 45
http://localhost/var/www/apps/conversion/tmp/Desktop/New%20Folder%20(2)/media/45_01EndocrineSystem_DV.mpg


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The endocrine system, along with the

nervous system, is responsible forcoordinating our responses.

The endocrine system is a slower system

and the nervous system is a fasterresponse.


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Chemical signals

Chemicals found in both systems and

also as part of other signaling

mechanisms bind to specific receptor

proteins on or in target cells.


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Secreted chemical signals include

Hormones produced by endocrine glands,

travel through the blood stream to target

organs

ex insulin, estrogen

Local regulators

(a) paracrine signals act on neighboring

cells, ex. cytokines, interferon,

prostaglandins(b) autocrine signals act on secreting cells

itself, ex cytokines


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Neurotransmitters - secreted by neurons at

synapses

ex- serotonin, nitric oxide (NO)

Neurohormones secreted by neurosecretory

cells, travel through the blood stream to target

organs or synapsesex- epinephrine

Pheromones released into the environment;

between individualsex insects marking trails,

mating, etc.
http://leadmedic.com/img/Pheromone2.jpg


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Fig. 45-2

Bloodvessel Response

Response

Response

Response

(a) Endocrine signaling

(b) Paracrine signaling

(c) Autocrine signaling

(d) Synaptic signaling

Neuron

Neurosecretorycell

(e) Neuroendocrine signaling

Bloodvessel

Synapse

Response


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Chemical Classes of Hormones

Three major classes of moleculesfunction as hormones in vertebrates:

Polypeptides (proteins and peptides)

Amines derived from amino acids Steroid hormones


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Fig. 45-3

Water-soluble Lipid-soluble

Steroid:

Cortisol

Polypeptide:

Insulin

Amine:

Epinephrine

Amine:

Thyroxine

0.8 nm


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Lipid-soluble hormones (steroidhormones) pass easily through cell

membranes, while water-soluble

hormones (polypeptides and amines)do not

The solubility of a hormone correlates

with the location of receptors inside oron the surface of target cells


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Water-soluble hormones are secreted by

exocytosis, travel freely in the

bloodstream, and bind to cell-surface

receptors

Lipid-soluble hormones diffuse across

cell membranes, travel in thebloodstream bound to transport

proteins, and diffuse through the

membrane of target cells


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Fig. 45-5-1

NUCLEUS

Signalreceptor

(a) (b)

TARGETCELL

Signal receptor

Transport

protein

Water-soluble

hormone

Fat-solublehormone

Fi 45 5 2


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Fig. 45-5-2

Signalreceptor

TARGETCELL

Signal receptor

Transport

protein

Water-soluble

hormone

Fat-solublehormone

Generegulation

Cytoplasmicresponse

Generegulation

Cytoplasmicresponse

OR

(a)NUCLEUS

(b)


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Multiple Effects of Hormones

The same hormone may have differenteffects on target cells that have Different receptors for the hormone

Different signal transduction pathways

Different proteins for carrying out the responsedue to different transcription factors theyactivate

A hormone can also have different effectsin different species

Fi 45 8 1


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Fig. 45-8-1

Glycogen

deposits

receptor

Vesseldilates.

Epinephrine

(a) Liver cell

Epinephrine

receptor

Glycogenbreaks downand glucose

is released.

(b) Skeletal muscle

blood vessel

Same receptors but differentintracellular proteins (not shown)

Fig 45 8 2


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Fig. 45-8-2

Glycogen

deposits

receptor

Vesseldilates.

Epinephrine

(a) Liver cell

Epinephrine

receptor

Glycogenbreaks downand glucose

is released.

(b) Skeletal muscle

blood vessel

Same receptors but differentintracellular proteins (not shown)

Epinephrine

receptor

Different receptors

Epinephrine

receptor

Vesselconstricts.

(c) Intestinal blood

vessel

N ti f db k d t i ti


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Negative feedback and antagonistic

hormone pairs are common features of the

endocrine system

Hormones are assembled into regulatory

pathways

A negative feedback loop inhibits aresponse by reducing the initial stimulus

Negative feedback regulates many

hormonal pathways involved inhomeostasis

Fig 45 11


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Fig. 45-11Pathway Example

Stimulus Low pH in

duodenum

S cells of duodenumsecrete secretin ( )

Endocrinecell

Bloodvessel

PancreasTargetcells

Response Bicarbonate release

I li d Gl C t l f Bl d


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Insulin and Glucagon: Control of Blood

Glucose an example of antagonistic

hormone pairs

The pancreashas clusters of endocrine

cells called islets of Langerhanswith alpha

cells that produce glucagon and beta cellsthat produce insulin

Insulin reduces blood glucose levels by

Promoting the cellular uptake of glucose

Slowing glycogen breakdown in the liver

Promoting fat storage


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Glucagon increases blood glucose levelsby

Stimulating conversion of glycogen to glucose in

the liver

Stimulating breakdown of fat and protein into

glucose

Remember: GlucagonGlucose ON!

Fig 45-12-2


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Fig. 45-12-2

Homeostasis:Blood glucose level

(about 90 mg/100 mL)

Insulin

Beta cells of

pancreasrelease insulininto the blood.

STIMULUS:Blood glucose level

rises.

Liver takesup glucoseand stores it

as glycogen.

Blood glucoselevel declines.

Body cellstake up moreglucose.

Fig 45-12-4


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Fig. 45 12 4

Homeostasis:

Blood glucose level


Glucagon

STIMULUS:

Blood glucose level

falls.

Alpha cells of pancreas

release glucagon.

Liver breaks

down glycogen

and releases

glucose.

Blood glucoselevel rises.

Di b t M llit


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Diabetes Mellitus

Diabetes mellitus is perhaps the best-known endocrine disorder

It is caused by a deficiency of insulin or a

decreased response to insulin in targettissues

It is marked by elevated blood glucose

levels


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Type I diabetes mellitus (insulin-dependent) is an autoimmune disorder in

which the immune system destroys

pancreatic beta cells Type II diabetes mellitus (non-insulin-

dependent) involves insulin deficiency or

reduced response of target cells due tochange in insulin receptors

Fig. 45-10


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Fig. 45 10

Major endocrine glands:

Adrenalglands

Hypothalamus

Pineal gland

Pituitary gland

Thyroid gland

Parathyroid glands

Pancreas

Kidney

Ovaries

Testes

Organs containingendocrine cells:

Thymus

Heart

Liver

Stomach

KidneySmallintestine

Coordination of Endocrine and


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Coordination of Endocrine and

Nervous Systems in Vertebrates

The hypothalamus receives information

from the nervous system and initiates

responses through the endocrine system Attached to the hypothalamus is the

pituitary gland composed of the

posterior pituitary and anterior pituitary


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The posterior pituitary stores andsecretes hormones that are made in the

hypothalamus

The anterior pituitary makes andreleases hormones under regulation of

the hypothalamus

Fig. 45-14


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g

Spinal cord

Posteriorpituitary

Cerebellum

Pinealgland

Anteriorpituitary

Hypothalamus

Pituitarygland

Hypothalamus

Thalamus

Cerebrum


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Hypothalamus

The hypothalamus secretes two

hormones which are stored in the posterior

pituitary.

1) oxytocin induces uterine contractions

during birth and milk production

2)ADH which decreases urine volume

Fig. 45-15


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Posteriorpituitary

Anteriorpituitary

Neurosecretorycells of thehypothalamus

Hypothalamus

Axon

HORMONE OxytocinADH

Kidney tubulesTARGET Mammary glands,uterine muscles

Th t i it it l d t


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The anterior pituitary gland secretes

releasing hormones and inhibiting

hormones.

TSH thyroid stimulating

FSH and LH stimulates gonads

ACTH - stimulates adrenal cortex Prolactin milk production

MSH stimulates production of

melanocytes (skin pigments)

GH growth hormone

Fig. 45-17


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Hypothalamicreleasing andinhibiting

hormones

Neurosecretory cellsof the hypothalamus

HORMONE

TARGET

Posterior pituitary

Portal vessels

Endocrine cells ofthe anterior pituitary

Pituitary hormones

Tropic effects only:FSHLHTSHACTH

Nontropic effects only:ProlactinMSH

Nontropic and tropic effects:GH

Testes orovaries

Thyroid

FSH and LH TSH

Adrenalcortex

Mammaryglands

ACTH Prolactin MSH GH

Melanocytes Liver, bones,other tissues

Tropic Hormones


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Tropic Hormones

A tropic hormone regulates the functionof endocrine cells or glands

The four strictly tropic hormones are

Thyroid-stimulating hormone (TSH) Follicle-stimulating hormone (FSH)

Luteinizing hormone (LH)

Adrenocorticotropic hormone (ACTH)


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Thyroid Gland

T3 and T4, regulates metabolism (needs

dietary iodine to function properly goiter)

Calcitonin lowers calcium in blood

deposition in bones and secretion into

kidney filtrate


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Parathyroid Gland

PTH parathormone raises calcium levels

in blood from bones and reuptake in

kidneys

Fig. 45-20-2


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PTH

Parathyroid gland(behind thyroid)

STIMULUS:Falling blood

Ca2+ level

Homeostasis:Blood Ca2+ level


Blood Ca2+

level rises.

Stimulates Ca2+uptake in kidneys

StimulatesCa2+ releasefrom bones

IncreasesCa2+ uptakein intestines

Activevitamin D


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Adrenal medulla

Epinephrine (adrenaline) raises

metabolic rate, fight or flight

Norepinephrine (noradrenaline) controls

blood pressure


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Adrenal cortex

Glucocorticoids glucose from noncarb

sources, such as muscles

Mineralocorticoids (aldosterone)

induces kidneys to reabsorb water and

salts

Both of these deal with long-term stress

Fig. 45-21c


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(b) Long-term stress response

Effects of

mineralocorticoids:

Effects of

glucocorticoids:

1. Retention of sodium

ions and water by

kidneys

2. Increased blood

volume and blood

pressure

2. Possible suppression of

immune system

1. Proteins and fats broken down

and converted to glucose, leading

to increased blood glucose

Adrenalgland

Kidney

Adrenal cortex


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Testes

Androgens (testosterone) gender, male

secondary sex characteristics


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Ovaries

Estrogen maintenance of female

reproductive system and development of

secondary female characteristics

Progesterone prepares uterus for child


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Pineal Gland

Melatonin biological clock

Hormonal pathways work with the


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Hormonal pathways work with the

hypothalamus and anterior pituitary to

coordinate responses

Ex in the gonads

GnRH (hypothalamus) affects FSH and LH

(anterior pituitary) which affects estrogens

and androgens (ovaries/testes)


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Which endocrine gland?

Too little of my hormone and you will

feel tired and sluggish and probably

gain weight.

THYROID

A malfunction in this gland can


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A malfunction in this gland can

result in a giant.

Anterior Pituitary

This gland prepares me for an


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This gland prepares me for an

emergency situation by increasing my

heartrate.

Adrenal

Glands

This gland is also used in the digestive


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This gland is also used in the digestive

system. It also comes into play when I

eat lots of M and Ms!

PANCREAS

This gland is called the master gland


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This gland is called the master gland

because it secretes nine hormones many of

which control other endocrine glands by

feedback control.

Pituitary

Gland

If this gland is not working


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If this gland is not working

properly, diabetes can result.

Pancreas

If this gland is not working properly, your


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If this gland is not working properly, your

nerves and muscles will not function

properly either due to calcium deficiency.

ParathyroidGland

Th l d d t f ti l i


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These glands do not function properly in

chromosomal mutations such as in Turners

and Klinefelters syndrome.

Gonads

This gland makes me wake up in the


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This gland makes me wake up in the

morning and ready to go!

Pineal Gland

endocrin system

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