Endocrine System

Chapter 8

Overview of Hormones

The endocrine and nervous systems often work together to bring about homeostasis.

The blood stream transports hormones throughout the body.

Overview of Hormones

Each hormone acts on a certain type of tissue called its target tissue.

Organs, tissues, or cells lacking the specific receptor do not respond to its stimulating effects.

Negative Feedback Loop

A decrease in function in response to a stimulus

The system controls how much product it makes by shutting down manufacturing when levels of output or the amount of accumulated product gets too high Example # 1: the regulation of the blood glucose

level in the body Example # 2: regulation of body temperature

Negative Feedback Loop

Positive Feedback Loop

An increase in function in response to a stimulus

“A” produces more of “B” which in turn produces more of “A”

Only a few positive feedback loops occur in the human endocrine system. Example: the process of birthing a child

Positive Feedback Loop

Glands

Glands

Exocrine glands – secretions released into ducts opening onto an epithelial surface

Endocrine glands – ductless organs that secrete their molecules directly into the bloodstream

Glands

Endocrine glands are activated by other hormones

Hypothalamus

Controls the pituitary gland Receives information from the nervous

system

Pituitary

Location: Inferior to the hypothalamus Known as the master gland

I. Anterior Pituitary

1. Growth hormone (GH) General metabolic hormone Major effects are directed to growth of skeletal muscles and

long bones

I. Anterior Pituitary

2. Prolactin (PRL) Stimulates and maintains milk production following

childbirth Function in males is unknown

I. Anterior Pituitary

3. Adrenocorticotropic hormone (ACTH) Regulates endocrine activity of the adrenal cortex

which makes a hormone called cortisol (helps the body manage stress)

I. Anterior Pituitary

4. Thyroid-stimulating hormone (TSH) Produces the hormone thyroxine

Regulates the rate of metabolism

I. Anterior Pituitary

Gonadotropic hormones – Regulate hormonal activity of the gonads 5. Follicle-stimulating hormone (FSH)

Stimulates follicle development in ovaries Stimulates sperm development in testes

I. Anterior Pituitary

Gonadotropic hormones – Regulate hormonal activity of the gonads 6. Luteinizing hormone (LH)

Triggers ovulation Prepares uterus for fertilized egg Stimulates testosterone production in males

II. Posterior Pituitary

1. Oxytocin Stimulates contractions of the uterus during labor Causes milk ejection

II. Posterior Pituitary

2. Antidiuretic hormone (ADH) Can inhibit urine production In large amounts, causes vasoconstriction leading to

increased blood pressure

Posterior Pituitary Anterior Pituitary

Mnemonic Device for anterior and posterior pituitary gland Anterior pituitary

FLAT PIG FSH LH ACTH TSH

Prolactin (Ignore) Growth Hormone

Posterior pituitary Audio Osmosis = AO = ADH and Oxytocin

Mnemonic Device

Hormone Targeted Area Produces

F FSH Ovaries and Testes

Sperm and egg 

L LH Ovaries and Testes

Ovulation and testosterone 

A ATCH Adrenal Gland CortisolT TSH Thyroid ThryoxineP Prolactin Breast MilkI Ignore - -G GH Muscles and

bonesGrowth of muscles and bones

Anterior Pituitary Gland Chart

Mnemonic Device

Hormone Targeted Area Produces

A ADH Kidneys Inhibit urine production

O Oxytocin Uterus and breast Uterine contraction and milk letdown

Posterior Pituitary Gland Chart