Mrs. Degl 1

The Endocrine System

Mrs. Degl 2

The human endocrine system is made up of glands, that secrete hormones into the blood. Hormones are transported by the circulatory system to organs and tissues on which they act.

Glands of human endocrine system:

1.Hypothalamus 2.Pituitary3.Thyroid 4.Parathyroid5.Adrenal6. Islets of Langerhans7.Gonads (ovaries and testes)

Mrs. Degl 3

Hypothalamus is a small part of the brain the secretes hormones.

Pituitary Gland is located at the base of the brain. It secretes many hormones.

1. Growth Stimulating Hormone is a pituitary hormone that has widespread effects in the body as well as growing long bones.

2. Thyroid Stimulating Hormone (TSH) is a pituitary hormone that stimulates the secretion of the thyroid hormone thyroxin.

3. Follicle Stimulating Hormone (FSH) is a pituitary hormone that stimulates the development of follicles in the ovaries of females. In males, it influences sperm production.

Mrs. Degl 4

Thyroid Glands are located in our necks. It secretes thyroxin, which contains iodine, and regulates the metabolism of the body cells. A normal level is essential for appropriate mental and physical development

Parathyroid Glands are embedded in back of the thyroid gland. They secrete parathormone. This controls calcium metabolism, which is required for normal nerve function, blood clotting, and proper growth of teeth and bones.

Mrs. Degl 5

Adrenal Glands•An adrenal gland is located on top of each kidney.•The outer layer is the adrenal cortex•The inner layer is the adrenal medulla•The adrenal cortex secretes two types of steroid hormones.•One type increases glucose levels in the blood.•One type stimulates the absorption of sodium from the kidney into the bloodstream. This affects blood pressure.•The adrenal medulla secretes the hormone adrenaline, which increases the blood glucose levels and accelerates the heartbeat and breathing rates. Adrenaline is released during times of stress and heavy exercise.

Mrs. Degl 6

Islets of Langerhans

•Small groups of cells that are found throughout the pancreas.•Secretes the hormones insulin and glucagon.•Insulin promotes the absorption of glucose into the body.

•Glucagon increases the blood glucose level.•Through their opposite effects, insulin and glucagon maintains homeostasis in the body by keeping the blood glucose levels within certain limits.

Mrs. Degl 7

Gonads

•The gonads (testes and ovaries) are endocrine glands.•The testes secrete testosterone, which stimulates the growth of male sex organs, sex characteristics, and production of sperm.•The ovaries secrete estrogen and progesterone.•Estrogen influences the development of the female sex characteristics and egg production.•Progesterone stimulates the thickening of the uterus for pregnancy.

Mrs. Degl 8

Negative Feedback

Negative Feedback is how the endocrine system regulates hormone levels.

•The level of one hormone in the blood stimulates or inhibits the production of a second hormone.•The blood level of the second hormone in turn stimulates or inhibits the production of the first.•TSH (secreted by the pituitary gland) and thyroxin (secreted by thyroid) is a classic example of negative feedback.

This helps maintain homeostasis.

Mrs. Degl 9

Disorders of the Endocrine System

•Goiter is the enlargement of the thyroid gland and is most commonly caused by a lack of iodine in the diet.•Diabetes is a disorder in which the islets of Langerhans do not secrete enough insulin into the blood so the body’s blood glucose levels are too high.•Growth problems can usually be attributed to the pituitary gland.•Recent technology had allowed scientists to create insulin, human growth hormone, and thyroxin to combat some of these disorders.