chapter 50 endocrine system

7/27/2019 Chapter 50 Endocrine System

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CHAPTER 50

Endocrine Systems


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All the endocrine glands and other organs with hormone-

secreting cells

Heart

Adrenal glands (medulla and cortex)

Thyroid

Pineal

Parathyroids

Pancreas

Stomach and small intestine

Adipose tissue

Liver and kidneys

Ovaries (in females)

Anterior pituitary gland

Posterior pituitary gland

Hypothalamus

Cortex

Medulla (not visible)

Testes (in males)

Endocrine system

Figure 50.1

Different organs and glands secrete

different types of hormones


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Hormones - chemical signals produced by endocrine cells

-travel through the blood stream and act on their target cells

Endocrine system

Endocrine cells

Target cells

hormone


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Endocrine system

Amines

Proteins/peptides

: water soluble (except thyroid hormone)

=> unable to cross plasma membrane

=> signal through cell surface receptor



Amines or

proteins/peptide

3 types of hormones


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Endocrine system

Steroids

: lipid soluble => cross plasma membrane => bind to either cytosolic or

nuclear receptor



3 types of hormones

Amines

Proteins/peptides





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Endocrine system

Steroids

: lipid soluble => cross plasma membrane => bind to either cytosolic or

nuclear receptor



3 types of hormones

Amines

Proteins/peptides





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Endocrine system

Function in

- Metabolism

- Mineral Balance

- Growth and Differentiation

- Reproduction

- Response to stress




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! Only cells having the proper receptors can respond to a hormone

! Hormones activate only specific cells

! Hormone interacts noncovalently and reversibly with the receptor

" Prevents cell from being permanently stimulated

8

Endocrine system


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Endocrine system


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Link between Endocrine system and Nerve system

To venous

circulation

Pituitary


Portal veins

Capillaries

Hypothalamus ()

Hypothalamus

Hypothalamic nuclei

1) make neurohormones

Infundibular

stalk

Arterial blood

supply

Anterior

pituitarygland

()

3) Travel through portal vein

to anterior pituitary gland

2) Neurohormones are released from axo

of hypothalamic neurons into capillaries


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To venous

circulation

Pituitary


Portal veins

Capillaries

Hypothalamus ()

Hypothalamus

Hypothalamic nuclei


2) Neurones secrete neurohormo into capillaries

Infundibular

stalk

Arterial blood

supply

Anterior

pituitarygland

()



4) Anterior pituitary gland synthesize several hormones

5) Secrete into the circulation hormones

neurohormones


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To venous

circulation

Pituitary


Portal veins

Capillaries

Hypothalamus ()

Hypothalamus

Hypothalamic nuclei


2) Neurones secrete neurohormo into capillaries

Infundibular

stalk

Arterial blood

supply

Anterior

pituitarygland

()



4) Anterior pituitary gland synthesize several hormones

5) Secrete into the circulation hormones

neurohormones


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Hormonal Control of Metabolism and Energy Balance

e.g., Thyroid hormone ()

!Increase Glucose metabolism

!Increase in heat production


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Hormonal Control of Metabolism and Energy Balance

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-

Hypothalamus

TRH

TSH

Thyroid

Anterior

pituitarygland

Normal levels

of T4and T3

T4 and T3

inhibit TRH secretion

as well as expression

of TRH precursor

negative

feedback

1) TRH (thyrotropin -releasing hormone)

Is released from hypothalamus

2) TSH (thyroid-stimulating hormone)

Is released from anterior pituitary gland

3) T4 and T3 (thyroid hormones)

is released from thyroid

Keeping balance

e.g., Thyroid hormone () Fig 50.6


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Diseases caused by too little or too much Thyroid Hormone

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Hypothyroidism


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16

-

Hypothalamus

TRH

TSH

Thyroid

Anterior

pituitarygland

Normal levels

of T4and T3

T4 and T3


as well as expression

of TRH precursor

negative

feedback

1) Decrease in TSH (thyroid-stimulating hormone)

2) Decrease in T4 and T3 (thyroid hormones)

-most common cause of hypothyroidism

=> Weight gain, sensation of coldness

Keeping balance

Hypothyroidism :Low T3, T4


Fig 50.6


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17

-

Hypothalamus

TRH

TSH

Thyroid

Anterior

pituitary

gland

Normal levels

of T4and T3

T4 and T3


as well as expressionof TRH precursor

negative

feedback

Increase in TSH (thyroid-stimulating hormone)

Thyroid cells are destroyed by immune cells

=> Decrease in T4 and T3 (thyroid hormones)

Hypothyroidism

e.g., Hashimotos thyroiditis :autoimmune disease

Promote the abnormal growth of thyroid : Goit


Fig 50.6


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Hyperthyroidism(overactive thyroid gland)

Graves disease: - autoimmune disease

-caused by hyperthyroidism

Causes: Production of antibodies against TSH receptor present on Thyroid

follicular cells

=> constitutively active

receptor (TSH receptor is always active)

=> Excessive production of T3 T4

=> weight loss, heat intolerance

Protruding eyeballs



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19

Hypothalamus

Thyroid

Anterior

pituitarygland

4)Excess TRH

5)Excess TSH & overstimulation

of thyroid

1) Reduced iodine intake

2) Low T4and T3due to lack of

iodine

3) Reduced

negativefeedback

6)Enlarged

thyroid

Diet can affect production of thyroid hormone :

Iodine is required for T4, T3 production



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Glucose Homeostasis

PancreasSmall intestine

Pancreatic

islets of Langerhans

:spherical clusters of

endocrine cells

Beta cells

produce

insulin

Alpha cells

produce

glucagon

glucagon

Insulin

=>Produced in pancreas

Two hormones involved in Glc Homeostasis


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Glucose Homeostasis

PancreasSmall intestine

Pancreatic

islets of Langerhans

:spherical clusters of

endocrine cells

Beta cells

produce

insulin

Alpha cells

produce

glucagon

glucagon

Insulin

=>Produced in pancreas

Two hormones involved in Glc Homeostasis


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Glucose Homeostasis

Homeostasis : bodys tendency to maintain relatively constant internal condition


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Glucose Homeostasis

3) insulin stimulate

glucose uptake

into cells

(mainly in adipose orskeletal muscle

Cells)

1) Glucose level

Increases above normal

(eating)

Normal blood

glucose level

2) Stimulate secretion of

insulin from Pancreas


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Glucose

molecule

Insulin

receptor

Without insulin

GLUT (glucose transporter)

Glucose Homeostasis


glucose uptakeinto cells

(mainly in adipose or

skeletal muscle

Cells- express glucose

transporter GLUT)

1) Glucose level


(eating)



Most of GLUTs are

located membrane bound

vesicles inside the cells

And only a few are

present in plasms

membrane.


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Glucose Homeostasis


glucose uptake

into cells


Cells)

1) Glucose level


(eating)



Insulin

receptor

With insulin

Insulin

Insulin stimulate movement

Of these GLUT to the plasma

Membrane

=> Increased glc uptake


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Glucose Homeostasis


glucose uptake

into cells


Cells)

4)Blood glucose

level decreases.

1) Glucose level


(eating)

Normal blood

glucose level




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Glucose Homeostasis

Liver

4)Blood glucose

level increases.

1) Glucose level

decreases above normal

(fasting)

Normal blood

glucose level

2) glucose-monitoring

regions in the hypothalamus

stimulate production of

glucagon from Pancreas

3) High Glucagon

Glycogen Noncarbo

hydrates

Glucose

Glucose

glycogenolysis

Gluconeogenesis

(generation of

Glc)

3)Glucagon stimulates


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Glucose Homeostasis

When blood glucose

level increases.

Normal bloodglucose level

When blood glucose

level decreases.

Insulin from pancreas

Glucagon from pancreas

Blood glucoselevel increases.

Blood glucose

level decreases.


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Glucose Homeostasis

When blood glucose

level increases.

Normal bloodglucose level

When blood glucose

level decreases.

Insulin from pancreas

Glucagon from pancreas

Blood glucoselevel increases.

Blood glucose

level decreases.

What happens if this system doesnt work?


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Diabetes

! Type 1 Diabetes mellitus (T1DM)



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Diabetes


" Autoimmune disease where immune system destroyes beta cells =>can not produce insulin

when blood glc increases => no insulin production => accumulation of

Glc in blood

" Also calledjuvenile diabetes(usually diagnosed in children and

Young adults)

" Treated by administration of insulin


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Diabetes



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Diabetes


Most common form of diabetes

2) Diminished Glc uptake

1) Insulin cant signal

to Glucose transporter

1) Pancreas do not produce enough insulin (but not by the attack of immune cells)

2) cells of the body lose much of their ability to respond to insulin

Insulin resistance

Constant high blood Glc level


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Diabetes


Many life style factors are important in development of Type 2diabetes

: High level of Physical activity

Healthy diet

Keeping normal weight

no smoking

=> 89% lower chance to get

type II diabetes

Obesity is cause for over than 1/2 of type II diabetes


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Diabetes

Type 2 Diabetes mellitus (T2DM)


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Control of growth and differentiation

anterior

pituitary

Produces Growth hormone (GH)

Produces IGF1 (insulin like growth factor-1)

Liver

Elongation of bonesduring puberty

Gonadal hormone

: seal growth plate( )


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2

When a person develop a tumor

causing the production of

excessive GH during childhood

-> becomes very tall -> Pituitary giant


If a person develop a tumor

causing the production of

excessive GH after puberty,

-> develops a condition called

Acromegaly (enlargement and thickening of feet and hands)


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3

low amount of GH produced => Short stature

Can be treated by injection of GH

e.g, Lionel (Leo) Messi



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4

Stress Hormone

1. Increase heart rate to maximize blood pumping

2. Maximize oxygen intake3. Increase production of glucose to provide

energy to muscle cells

4. Increase alertness

Stress

Cortisol

(a member of glucocorticoids)

Adrenal

cortex

Anterior

pitutiary

Hypothalamus

ACTH

released into

blood

Secete Releasing

factor

Acute stress (Table 50.3)


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5

Stress Hormone

1. Lower immune systems

2. Slow down thinking

3. Create blood sugar imbalances4. Raise your blood pressure

5. Weaken muscle tissue

6. Decrease bone density

7. Craving for sweets and carbohydrate

8. Increase fat to stomach areas

Stress

Cortisol

(a member of glucocorticoids)

Adrenal

cortex

Anterior

pitutiary

Hypothalamus

ACTH

released into

dlood

Secete Releasing

factor

Exposure to Chronic stress

chapter 50 endocrine system

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