Endocrine SystemKelsey JacksonAD BradleyHailey Bell

Period 3

Functions of Endocrine System

•Regulating the functions of the body to maintain homeostasis.

•Coordinate with the nervous system functions.

•Oversee cell to cell communication using chemical signals.

Characteristics

•Like the nervous system, the endocrine system exerts precise effects in helping regulate metabolic processes.

• The Endocrine System includes cells, tissues, and organs that make up a network of glands that secrete hormones, which travel in the blood stream and affect the functioning of target cells

Nervous System vs. Endocrine System

Secretions

•Paracrine secretions act locally, only affecting neighboring cells.

•Autocrine secretions act on cells that make them, only the secreting cell itself.

•Exocrine glands secrete through tubes and ducts.

Major Endocrine Glands

Hormone Action

•Endocrine glands secrete hormones that affect target cells with specific receptors

•Chemical hormones are:▫Steroids▫Amines▫Peptides▫Proteins▫Glycoproteins

Steroid Hormones

•Steroid hormones enter a target cell and bind receptors forming complexes in nucleus.

•Complexes activate specific genes so that specific proteins synthesize.

The following events occur:1. The lipid-soluble steroid hormone diffuses

through the cell membrane2. The steroid hormone binds a specific

protein molecule-the receptor for that hormone.

3. The resulting hormone-receptor complex binds within the nucleus to particular regions of the target cell’s DNA and activities transcription of specific genes into messenger RNA (mRNA) molecules.

4. The mRNA molecules leave the nucleus and enter the cytoplasm.

5. The mRNA molecules associate with ribosomes to direct the synthesis of specific proteins.

Steroid Hormones

Non Steroid Hormones

The mechanism works as follows:1.A hormone binds its receptor.2.The resulting hormone-receptor complex

activates a protein called a G protein.3.The G protein activates an enzyme called

adenylate cyclase, which is a membrane protein.

4.Activated adenylate cyclase catalyzes the circularization of ATP in the cytoplasm into cAMP.

Nonsteroid Hormone

Control of Hormone Secretions

•Concentration of each hormone is regulated in the body

•Endocrine glands secrete hormones in response to hormones that the hypothalamus secretes

•Other glands secrete hormones in response to nerve impulses

•Negative feedback mechanisms guide these hormone secretions

• Glands sense hormone concentration

Control of Hormone Secretions

• If hormone secretion reaches a certain concentration the gland is inhibited and can no longer secrete

• Negative feedback systems maintain stable hormone concentrations

Pituitary Gland

•Anterior pituitary hormones- Secretes growth hormones, prolactin, thyroid-stimulating hormone, adrenocorticotropic hormone, follicle-stimulating hormone and luteinizing hormone

•Growth hormones- Stimulates cells to grow and divide more frequently

Pituitary Gland

Pituitary Hormones

• Prolactin- Stimulates and sustains women’s milk production

• Thyroid stimulating hormones- Controls secretion of hormones from thyroid gland- Hypothalamus secretes throtropin-releasing hormones that regulates thyroid stimulating hormones

Adrenocorticotropic Hormone

•ACTH controls secretion of hormones from the adrenal cortex

•The hypothalamus secretes thyrotropin-releasing

• Hypothalamus secretes corticotropin-releasing hormone that regulates thyroid secreting hormones

Posterior Pituitary Hormones

•Posterior lobe of pituitary gland consists largely of neurological cells and nerve fibers

• Hypothalamus produces hormones of the posterior pituitary

•Antidiuretic hormone reduces volume of water that the kidney excretes

Oxycotin

•Oxycotin contracts muscles in the uterine wall

•Also contracts cells associated with producing and ejecting milk

Thyroid Gland

•Consists of two lobes in the neck• Includes many follicles•The follicles are fluid filled and store

hormones•Thyroid Hormones

- Thyroxine and triiodothyronine increase the metabolic rate of cells, enhance protein synthesis and stimulate lipid utilization - Calcitonin helps regulate concentrations of blood calcium and phosphate ions

Thyroid Gland

Parathyroid Glands•Located on the posterior surface of the

thyroid gland•Structure

- Each parathyroid gland consists of secretory cells that are well supplied with capillaries

•Parathyroid Hormone- Parathyroid hormones increase blood calcium level and decrease blood phosphate ion concentration- Negative feedback mechanisms operate between parathyroid glands and the blood

Adrenal Glands

•Adrenal glands are closely associated with the kidneys.

•Located atop each kidney like a cap and is embedded in the mass of adipose tissue that encloses the kidney.

Structure of Adrenal Glands

•Each gland consists of an adrenal medulla and an adrenal cortex.

•The glands are functionally distinct and secrete different hormones.

Hormones of Adrenal

Adrenal Glands

Hormones of Adrenal Medulla and Adrenal Cortex

Medulla: 1.Cells of adrenal medulla secrete

epinephrine (adrenalin) and norepineephrine.

Cortex: 1.Produces several steroid hormones2.Aidosterone is a mineralocorticoid that

cause the kidneys to conserve sodium ions and water to secrete potassium ions.

Adrenal Sex Hormones

•These hormones are male types, adrenal androgens, but some are converted to female hormones, estrogens, in the skin, liver, and adipose tissue.

•May supplement the supply of sex hormones from the gonads and stimulate early development of reproductive organs.

Pancreas•Structure

- Attached to small intestine- Pancreatic islets secrete glucagon and insulin

• Hormones of the pancreatic islets- Glucagon stimulates the liver to produce glucose from glycogen and non-carbohydrates

- Insulin moves glucose across cell membranes that stimulate glucose and fat storage and promotes protein synthesis.

Pancreas

Pineal Gland

•Attaches to the thalamus• Secretes melatonin in response to

varying light conditions• Melatonin may help regulate the female

reproduction cycle by inhibiting gonadotropin secretion from the anterior pituitary.

Thymus Gland

•Lies between the sternum and between the lungs

•Secretes thymosins, which affect the productions of certain lymphocytes that function in immunity

Reproductive Glands

•Ovaries secrete estrogens and progesterone and gonadotropin

• Testes secrete testosterone

Digestive Glands

•Certain glands of the stomach and small intestine secrete hormones

Other hormone producing glands• The heart and the kidneys produce

hormones

Stress and Health

•Types of stress-Physical stress results from environmental factors that are harmful to tissues- Psychological stress results from thoughts about real or imagined dangers

• Response to stress- Responses to maintain homeostasis - Hypothalamus controls general stress syndrome

Endocrine System Diseases

Diabetes- One of the more prevalent endocrine system diseases, diabetes is a condition in which the pancreas does not produce enough of the hormone insulin or the body does not effectively use the insulin it does produce. Because insulin is instrumental in helping the body convert sugars and starches into necessary energy, there can be serious consequences if diabetes is left undiagnosed and/or untreated.

Endocrine System Diseases

Cushing’s Syndrome- Cushing's syndrome, less common than the endocrine system diseases discussed above, occurs as the result of too much Cortisol in the blood for an extended period of time. Cortisol is a hormone that, in normal amounts, helps the body perform a number of important functions including converting fat into energy, maintaining immune system function, and responding to stress.

Endocrine System DiseasesGrowth Disorders- Given that the endocrine

system regulates growth processes, endocrine system diseases often result in growth disorders. If the body produces too much growth hormone (GH), gigantism or acromegaly (gigantism in adults) can occur; too little growth hormone results a condition called growth hormone deficiency, or GHD, which can cause children to grow more slowly than normal.

Work Cited• Raji, Annaswamy. "Endocrine System Diseases: Cushing's

Syndrome, Addison's Disease and More." Endocrine System Diseases, Symptoms & Treatment: The Hormone Health Network. The Endocrine Society, n.d. Web. 21 Mar. 2013. <http://www.hormone.org/endocrine_system_diseases.cfm>.

• Shier, David, Jackie Butler, and Ricki Lewis. "Endocrine System." Hole's essentials of human anatomy and physiology. 9th ed. Boston: McGraw-Hill, 2006. 276-301. Print.

• Images courtesy of Hole’s essential of human anatomy and physiology.