The Endocrine System (Part 1)

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The Endocrine System:

1. What is the Endocrine System?

•The Endocrine System influences almost every cell, organ, and function of our bodies.

•It is a collection of glands and organs that produce and regulate hormones in the bloodstream to control many bodily functions.

•Whereas the nervous system responds to and controls body processes which occur quickly and last for a short amount of time, the endocrine system is responsible for many of the slow acting changes which may last for hours, even days.

•Regulates: mood, growth, development, tissue function, metabolism, sexual function, and reproductive processes.

•The endocrine system helps to maintain homeostasis.

2. Glands-

•A gland is a group of cells that produces and secretes (gives off) chemicals called hormones to specific cells in the body- "target cells"

o Target Cells- any cell that has a specific receptor for an antigen or antibody or hormone or drug, or is the focus of contact by a virus or phagocyte or nerve fiber etc.

3. Hormones-

•The body's chemical messengers that transfer information and instructions from one set of cells to another.

•The hormones which all move along the bloodstream are each designed for a specific task and will only affect certain (Target) cells

•After the hormones reach the correct target cell, it links to a receptor spot, which tells the cell what to do next.

o The hormone will not interfere with a non-target cell, and the target cell won't react to any other chemical than its specific hormone.

4. Endocrine System and Homeostasis-

•The endocrine system and homeostasis are related primarily in that certain causes of imbalance may be corrected through endocrine intervention.

o Seen when homeostasis is being thrown out of balance due to hormonal causes

5. Parts of the Endocrine System-

•pituitary gland, hypothalamus, and pineal gland (Brain)

•thyroid and parathyroid (Throat)

•thymus, adrenal glands, and pancreas (abdomen)

•gonads- testes or ovaries (lower abdomen)

a. Pituitary Gland- (“Master Gland”)

•The hormones of the pituitary gland help regulate the functions of other endocrine glands.

•The pituitary gland is only about 1/3 of an inch in diameter (that’s about as large as a pea) and located at the base of the brain.

o connected by the infundibulum, or more simply, the pituitary stalk.

•The pituitary gland has two parts—the anterior lobe and posterior lobe—that have two very separate functions.

•The anterior lobe releases hormones upon receiving releasing or inhibiting hormones from the hypothalamus.

•The posterior lobe does not produce hormones (this is done by nerve cells in the hypothalamus) but it does release them into the circulation.

i. Hormones of the Pituitary Gland:

•Anterior Lobe:

o Adrenocorticotropic hormone (ACTH): ACTH stimulates the adrenal glands to produce hormones.

o Follicle-stimulating hormone (FSH): FSH works with LH to ensure normal functioning of the ovaries and testes.

o Growth hormone (GH): GH is essential in early years to maintaining a healthy body composition and for growth in children. In adults, it aids healthy bone and muscle mass and affects fat distribution.

o Luteinizing hormone (LH): LH works with FSH to ensure normal functioning of the ovaries and testes.

o Prolactin: Prolactin stimulates breast milk production.

o Thyroid-stimulating hormone (TSH): TSH stimulates the thyroid gland to produce hormones.

• Posterior Lobe:

▪ Contains the ends of nerve cells coming from the hypothalamus.

o Antidiuretic hormone (ADH): This hormone prompts the kidneys to...
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