ENDOCRINE SYSTEM

Classes of Chemical Messengers

1. Autocrine – stimulates the cell that originally

secreted it (eg. Eicosanoids)

2. Paracrine – local action on nearby cells (eg.

Histamine)

3. Neurotransmitter – produced by neurons and

secreted into a synaptic cleft (eg. Acetylcholine)

4. Endocrine – secreted into the blood stream (eg.

Thyroid Hormone, Insulin)

Functions 1.Metabolism

2.Control of Food Intake and Digestion

3.Tissue Development

4.Ion Regulation

5.Water Balance

6.Heart Rate and Blood Pressure Regulation

7.Control of Blood Glucose and other nutrients

8.Control of Reproductive Functions

9.Uterine Contraction and Milk Release

10. Immune System Regulation

Endocrine Glands

Pituitary Gland

Pituitary Gland Location:

- Posterior to the optic chiasm

Function:

Main: Control the function of other glands in the body

Other: Secrete hormones that influence growth, kidney function etc.

Hormonal Control

Direct Innervation

Thyroid Gland Location:

- 2 lobes on each side of the trachea, inferior to the

larynx

Function:

Main: Secrete Thyroid Hormones

- T3 (triiodothyronine)

- T4 (tetraiodothyronine)

Other: Secrete Calcitonin

Parathyroid Location

- Posterior wall of Thyroid gland

Function

- Secrete PTH (parathyroid hormone)

- essential for regulation of Ca

levels

ADRENAL GLANDS

o located at the top of each kidney

o produce hormones that help the body control blood sugar, burn protein and fat, react to stressors, and regulate blood pressure

o consists of two main parts: the adrenal cortex and the adrenal medulla

ADRENAL CORTEX -outer portion of the adrenal gland -divided into 3 regions, namely: Zona glomerulosa, Zona fasciculata, and Zona reticularis Zona glomerulosa -outermost layer -secretes the first class of hormones, mineralocorticoids Aldosterone- major mineralocorticoid hormone -raises blood levels of Na+, increases water retention, and lowers blood potassium level Zona fasciculata -middle layer -secretes the second class of hormones, glucocorticoids Cortisol- major glucocorticoid hormone Increases breakdown of proteins and lipids Help fight against stress and inflammation HYPERSECRETION – Cushing’s Syndrome HYPOSECRETION – Addison’s Disease Zona reticularis -innermost layer -secretes gonadocorticoids -supplement sex hormones (Androgens and small amount of Estrogens) HYPERSECRETION – exaggerated male characteristics HYPOSECRETION – congenital adrenal hyperplasia

ADRENAL MEDULLA

-inner portion of the adrenal gland

-function together with the sympathetic division of the

autonomic nervous system

-contains chromaffin cells, which secrete 2 hormones:

Epinephrine and Norepinephrine

-effects of these hormones resemble sympathetic

stimulation

REGULATION OF ALDOSTERONE SECRETION FROM THE ADRENAL CORTEX

REGULATION OF CORTISOL SECRETION FROM THE ADRENAL CORTEX

REGULATION OF ADRENAL MEDULLARY SECRETIONS

Pancreas

• flat, pear-shaped gland

• fifteen (15) cm or 6 in long

• in the upper abdomen (retroperitoneum); behind

the stomach next to duodenum

• network of tubes or pancreatic ducts

• aids in digestion, contains powerful enzymes

PARTS

-Head – widest part

-Body – middle section

-Tail – narrowest part

-Islets of Langerhans – more simply called Pancreatic

Islets

2 FUNCTIONS -Exocrine Salts & Enzymes Duodenum

HCO3

- - neutralize gastric acid (HCl) Pancreatic amylase Starch Smaller Carbs

Lipases - break down fats Proteases Trypsinogen Enteropeptidase trypsin Chymotrypsinogen Trypsin chymotrypsin

-Endocrine Hormones Bloodstream

Glucagon - alpha cell; raises the blood glucose level Glycogen Glucose

Insulin – beta cell; decreases the blood glucose level Glucose Glycogen

Somatostatin – delta cell; inhibit both glucagon and insulin secretion Pancreatic polypeptide - inhibits secretion of pancreatic juice

INSULIN • is released from the beta cells

• produced in the pancreas by the islets of

Langerhans

• regulate the amount of glucose in the blood.

• lack of insulin causes a form of diabetes.

• major target tissues for insulin are the liver, adipose

tissue, muscles, and the area of the hypothalamus

that controls the appetite, called the satiety center

which means fulfillment of hunger

• Insulin binds to membrane- bound receptors and

either directly or indirectly, increases the rate of

glucose and amino uptake in these tissues.

• GLUCOSE is converted to GLYCOGEN or LIPIDS

• AMINO ACIDS are used to synthesize protein

Three Types of Diabetes 1) Type 1

• Is also called insulin-dependent diabetes. It used to

be called juvenile-onset diabetes, because it often

begins in childhood.

• Is an autoimmune condition. It's caused by the

body attacking its own pancreas with antibodies.

• Damaged pancreas doesn't make insulin.

2) Type 2

• Type 2 diabetes used to be called adult-onset

diabetes

• Was also called non-insulin-dependent diabetes.

• With Type 2 diabetes, the pancreas usually

produces some insulin. But either the amount

produced is not enough for the body's needs, or the

body's cells are resistant to it. Insulin resistance, or

lack of sensitivity to insulin, happens primarily in

fat, liver, and muscle cells.

• weight management, nutrition, and exercise

• tends to progress

3) Gestational Diabetes

• Diabetes that's triggered by pregnancy

• It is often diagnosed in middle or late pregnancy.

Because high blood sugar levels in a mother are

circulated through the placenta to the baby,

gestational diabetes must be controlled to protect

the baby's growth and development.

• Careful meal planning to ensure adequate

pregnancy nutrients without excess fat and calories,

Daily exercise, Controlling pregnancy weight gain,

Taking diabetes insulin to control blood sugar levels

if needed

Testes and Ovary Testes

-produce sperm cells

Testosterone

-muscle enlargement, growth of body hair, voice changes, and male sexual drive

Ovaries

-produce oocytes

Estrogen and Progesterone

-enlargement of the breasts; distribution of fat; influences the shape of the hips, breasts and thighs

Progestin

-synthetic version of progesterone

Hypothalamus

-release of hormones controls the rate of LH and FSH secretion

-negative feed back effect

THYMUS GLAND

THYMUS

• lies on the upper part of our thoracic cavity

• important in function of our IMMUNE SYSTEM

Thymosin

• aids in the development of white blood cells called T CELLS

• most important EARLY IN LIFE

T Cells

• help protect the body against infection by foreign organisms

GLAND HORMONE TARGET

TISSUE

FUNCTION

Thymus Thymosin Immune Tissues Promotes

immune system

development

and function

PINEAL GLAND

PINEAL

• small pinecone-shaped structure located superior and posterior to the thalamus of the brain.

Melatonin

• inhibits the functions of the reproductive system

• longer day length causes decrease in

melatonin production

• plays an important role in the onset of puberty in humans

GLAND HORMONE TARGET

TISSUE

FUNCTION

Pineal Gland Melatonin Hypothalamus Inhibits secretion

of gonadotropin-

releasing

hormone thereby

inhibiting

reproduction.

OTHER HORMONES Stomach and Small Intestine

• secrete hormones that stimulate the production of gastric juices from the stomach, pancreas, and liver.

Prostaglandins

• widely distributed in tissues of the body

• function as intercellular signals

• plays an important role in inflammation

Kidneys

• secrete ERYTHROPOIETIN

Placenta

• secretes hormones that maintains pregnancy and stimulates breast development which are: Estrogen, Progesterone, Human Chorionic Gonadotropin which is similar in structure and function to LH.

EFFECTS OF AGING ON THE ENDOCRINE SYSTEM

• Age-changes include gradual decrease in:

a. Growth Hormone or GH

b. Melatonin

c. Thyroid Hormones

d. Renin

e. Reproductive Hormones

f. Thymosin

• Parathyroid hormone secretion increases

• Increase in type 2 diabetes in people with familial

tendency

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