1. Endocrine System

2. Objectives State the structures that make up the endocrine system
Describe the functions of the endocrine system

3. Introduction
The body needs to coordinate and integrate all of ifs functions into one harmonious whole. This is called homeostasis. The maintenance of homeostasis involves the growth, maturation, reproduction, and metabolism. The body system responsible for this coordination is the endocrine system.

4. Structures
Composed of numerous glands throughout the body that secrete hormones into the bloodstream and excrete chemicals to rid the bod of wastes
These chemicals are passed in the body through blood and tissues
Chemicals and hormones provide changes in the body that regulate growth, regulate sexual production and development, metabolize nutrients in cells, and maintain a homeostasis in the body allowing for a balance in the body system.

5. Endocrine Glands Secrete hormones directly into the bloodstream
Then transported to all areas of the body
Glands include:
Pituitary
Thyroid
Parathyroid
Adrenal
Thymus
Pancreas
Pineal
Gonads

6. Pituitary Gland Main gland
Works with the hypothalamus to control the endocrine system and create a link with the nervous system
Lies at the base of the brain and has an anterior and posterior lobe
Posterior lobe connects to the hypothalamus
Develops from brain tissue while an animal is in the embryo stage
Serves as a reservoir for hormones and allows for the release and regulation of hormones

7. Pituitary Gland Continued
The posterior or black lobe releases two peptide hormones: oxytocin and antidiuretic hormone (ADH)
Oxytocin plays vital role in parturition or labor
Hormone releases and causes muscles of the uterine wall to contract and milk production to begin in the mammary gland
ADH promotes urine formation, water absorption, controls blood pressure and changes control in water content

8. Pituitary Gland Continued
The anterior lobe is controlled by the hypothalamus
Main function is to release hormones into bloodstream and produce and regulate growth hormones within the body
Major growth hormone somatotropin increases protein synthesis within the body, thus increasing the size of the animal
Produces the hormone prolactin, which controls milk production
Pituitary Gland is often called the master gland as it controls the thyroid gland which regulates and secretes hormones within the body

9. Thyroid Gland
Can become overactive or underactive in animals, causing many conditions that can affect them
Produces thyroid stimulating hormone (TSH) and tells the thyroid when to produce thyroxine
controls the actions of the thyroid gland and cell metabolism
Two hormones found in the bloodstream that help identify normal or abnormal thyroid gland production are T3 and T4
T3 hormone is more potent and a more active hormone
T4 hormone is converted into tissues and breaks down fats and helps control cholesterol
Located in the neck and contains two lobes

10. Parathyroid Glands Located on the surface of the thyroid gland
Secrete parathormone
Helps regulate blood calcium and phosphorous levels

11. Adrenal Glands Lie cranial to the kidneys
Produce and release adrenaline and other hormones
Adrenaline is a chemical that is released by the nervous system in times of stress to create a response in an animals fight or flight instinct reaction
Also regulate function of ACTH or adrenocorticotropic hormone
Controls blood pressure, releases cholesterol, and also controls the body’s production of steroids

12. Pancreas
Serves a dual role in endocrine and exocrine production and functions
Produces and regulates insulin production
Insulin is regulated by the blood glucose level (AKA blood sugar)

13. Thymus A gland in young animals
Has immunologic functions through maturation of t-lymphocytes

14. Pineal Gland Located in a central portion of the brain
Plays a role in the regulation of body rhythms

15. Hormones
Made up of four major chemical groups that regulate parts of the body
Fatty acids control hormones involved in estrus in the female animal’s heat cycle
Steroids occur naturally in the body and regulate chemicals, such as cholesterol, in the body that control essential life functions
Amino acids are the simplest hormones and control the thyroid gland functions
Peptides are the largest hormones and control the proteins in the body