1. The Endocrine System

2. Importance of the Endocrine System:
Helps in the regulation of homeostasis
Regulate the body's growth, metabolism (the physical and chemical processes of the body), and sexual development and function
Works in conjunction with the nervous system to promote balance throughout the body
A source of communication in the body, just like that of the NS.
Both NS and Endocrine System have cell to cell contact.

4. What are hormones? Protein or steroid (lipid) based in nature.
Hormones are chemical messengers created by the body.
They transfer information from one set of cells to another to coordinate the functions of different parts of the body.

5. Major components of the Endocrine system:
The major glands of the endocrine system are:
Hypothalamus
pituitary
thyroid
parathyroids
adrenals
pineal body
reproductive organs (ovaries and testes)
pancreas is also a part of this system; it has dual role in hormone production as well as in digestion.

6. Two Types of Secretions
Target cells- are the cells acted on by hormones.
Hormones filter through the blood stream to target site (cells).
Some glands secrete directly into interstitial tissue and are rapidly broken down
Referred to as “local hormones.”
Two types Paracrine and Autocrine
Paracrine: affect neighboring cells ONLY
Autocrine: affect the secreting cell itself

7. How does the Endocrine System function?
The endocrine system is regulated by feedback in much the same way that a thermostat regulates the temperature in a room.
For the hormones that are regulated by the pituitary gland, a signal is sent from the hypothalamus to the pituitary gland in the form of a "releasing hormone," which stimulates the pituitary to secrete a "stimulating hormone" into the circulation.
The stimulating hormone then signals the target gland to secrete its hormone.
As the level of this hormone rises in the circulation, the hypothalamus and the pituitary gland shut down secretion of the releasing hormone and the stimulating hormone, which in turn slows the secretion by the target gland.
This system results in stable blood concentrations of the hormones that are regulated by the pituitary gland.

8. Hormones Regulated by the Hypothalamic/Pituitary System
Pituitary Stimulating Hormone
Hypothalamic Releasing Hormone
Thyroid hormones T4, T3
Thyroid-stimulating hormone (TSH)
Thyrotropin-releasing hormone (TRH)
Cortisol
Adrenocorticotropin hormone (ACTH)
Corticotropin-releasing factor (CRF)
Estrogen or testosterone
Follicle-stimulating hormone (FSH), luteinizing hormone (LH)
Luteinizing hormone-releasing hormone (LHRH) or gonadotropin-releasing hormone (GnRH)
Insulinlike growth factor-I (IGF-I)
Growth hormone
Growth hormone-releasing hormone (GHRH)

9. Exocrine Gland
Theses are glands that secrete to the external environment through ducts.
Examples:
Sweat glands
Ear wax
Pancreatic juice

10. Compare and Contrast NS and ES
Both have cell to cell communication
Both release chemical messengers
NS-neurotransmitters
NS-various receptors within the brain and spinal cord
ES- glandular cells release hormones
ES-Hormones are cell specific
ES-Receptors are glycoprotein's
Both help regulate homeostasis

11. Types of Hormones Protein- Amino Acid based
(glycoprotein's are formed by protein and carbohydrate)
Steroid- formed from cholesterol
(Major difference is in how they enter the cell)
Both stimulate the cells in even very low concentrations