THE ENDOCRINE SYSTEM

Its Parts and Functions

Nervous System - body control

Endocrine System - body regulator

What is a GLAND?

It is an organ that develops a secretion which performs

specific functions.

The Endocrine System

Is made up of ductless glands.

“Ductless” means without tubes

HORMONES

- Comes from the Greek word which means “to arouse”

- Are chemical messengers formed from substances taken from the blood.

- They circulate throughout the body & exert specific effects on tissues, organs or other glands located some distance away from the cells that secrete them.

Our body needs a certain hormone at one time , but not at all times.

(ex. Fireman’s adrenaline rush)

Your endocrine glands does not release hormones continuously. There are signals within the body that tell each gland to secrete hormones. There are also some signals that tell the gland to stop.

Pituitary Gland

LOCATION: found at the base of the brain

DESCRIPTION: called the “master gland” because it controls most of the other endocrine glands.

The pituitary gland has two lobes: The Anterior and Posterior

Hormones Released by the Anterior Pituitary

HORMONE TARGET TISSUES FUNCTION

1. Growth Hormone (GH)

Most tissues Stimulates cell division & growth of the muscles and

bones

2. Thyroid- Stimulating Hormone (TSH)

Thyroid Gland Increases the secretion of Thyroxine

3. Adrenocorticotropic Hormone (ACTH)

Adernal Cortex Increases the secretion of the medulla

4. Luteinizing Hormone (LH)

Ovaries/Testis Promotes ovulation & progesterone production

5. Follicle-Stimulating Hormone (FSH)

Follicles in ovarySeminiferous Tubules in

Testis

Promotes follicle maturation & estrogen secretion in ovary ;

sperm cell production in testis

6. Prolactin Ovary & Mammary Gland in females, testis in males

Stimulates milk production & prolongs progesterone

secretion following ovulation & during pregnancy

Hormones Secreted by the Posterior Pituitary

HORMONE TARGET TISSUES FUNCTION

1. Antidiuretic hormone (ADH)

Kidney Increases water reabsorption (less H2O) is

lost as urine2. Oxytocin -Uterus

-Mammary Gland-Increases uterine

contractions -increases milk “let-down”

from mammary glands

Pineal Glands

LOCATION: found near the base of the brain

DESCRIPTION: outgrowth of the brain

HORMONE SECRETED: Melatonin-regulates the body’s day & night cycle.

TARGET TISSUES – at least the hypothalamus

Thyroid Gland

LOCATION: at the base of the neck (just below the larynx

DESCRIPTION: soft, brownish-red organ shaped like a butterfly.

HORMONES SECRETED: Thyroxine-increases metabolic rates, essential for the normal

process of growth & maturation. Calcitonin-decreases the rate of bone breakdown.

TARGET TISSUES – Thyroxine- most tissues

Calcitonin – primarily bone

Parathyroid Gland

LOCATION: attached to the back of the thyroid gland

DESCRIPTION: 2 pairs of pea-sized glands

HORMONE SECRETED: Parathormone(Parathyroid Hormone)-helps control the

level of calcium in the blood

TARGET TISSUES – bone & kidney

Thymus Glands

LOCATION: located in the upper part of the chest, below the neck

DESCRIPTION: consists of 2 lobes

HORMONE SECRETED: Thymosin-promotes immune system

development & function

TARGET TISSUES – immune tissues

Adrenal Glands

LOCATION: found above the kidneys

DESCRIPTION: cone-shaped glands

HORMONE SECRETED: Adrenaline (Epinephrine)-also called “the emergency

hormone”. It prepares the body for physical activity. Cortisol(Glucocorticoids)-increase fat & protein breakdown

TISSUES – immune tissues

Pancreatic Glands

LOCATION: lies behind the stomach

DESCRIPTION: elongated & tapers at one end

HORMONE SECRETED: Insulin-lowers blood sugar level Glucagon-raises blood sugar level

TARGET TISSUES – Insulin-liver, skeletal muscle, adipose tissue Glucagon-liver

OvariesLOCATION: located on one side of the uterus

DESCRIPTION: pair of glands that functions to produce egg cells/ova.

HORMONE SECRETED: Estrogen-stimulate the dev’t of secondary female sex characteristics

(pubic hair, enlargement of breasts, etc). It is also responsible for the growth & dev’t of the external genitalia structure

Progesterone-it promotes growth of the uterine lining.Responsible also for sexual behavior.

TARGET TISSUES – Estrogen-most tissues Progesterone-most tissues

Testes

LOCATION: near the penis

DESCRIPTION: pair of glands that functions to produce sperm cells.

HORMONE SECRETED: Testosterone-Responsible for the development of secondary

sex characteristics (pubic hair, growth of beard, changes in voice quality, etc.). It also aids in sperm cell production.

TARGET TISSUES – Testosterone-most tissues

Summary

• Some endocrine glands perform only hormonal functions. Others are mixed glands. They produce hormones and perform other functions as well.

• Each part of the endocrine system produces different hormones that affect other parts of the body.

Quiz

Write TRUE if the statement is true . If the statement is FALSE, change the underlined word or phrase to make it true.

______1. The parts of the endocrine system are not connected to one another.

______2. Endocrine glands are ductless glands.

______3. The endocrine system controls the body through nerve impulses.

______4. Oversecretion of the growth hormone causes dwarfism.

______5. Insulin lowers the amount of calcium in the blood.

______6. When blood sugar level is low, glucagon raises it.

______7. The testes produces estrogen.

______8. The hormone that stimulates the body for fight or flight is thymosin.

______9. The body’s biological clock is stimulated by melatonin produced by the pineal gland.

______10. The menstrual cycle in females is stimulated by testosterone and progesterone.

ASSIGNMENT

Research for pictures of people who have DISORDERS of Endocrine System. Name the disorder and paste it on your notebook.