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Endocine System
Flashcards on the Endocrine system
38
Anatomy
Undergraduate 2
11/08/2010

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Term
The Endocrine System
Definition

- Works with nervous system to maintian body homeostasis

- regulates long term processes like growth and the reproductive system

- Is comprised of specific glands that secrete hormones into the blood that ultimately alter the activities of specific "target" organs

Term
Exocrine Glands
Definition
Secretions released into ducts opening onto an epihelial surface
Term
Endocrine glands
Definition

ductless organs that secrete their molecules directly into the bloodstream

- hormone passes through blood

Term
Glands and Hormones
Definition

- All endocrine cells are located within highly vascularized areas to ensure that their products enter the bloodstream immediately

- Hormones are molecules that have a specific effect on specific organs

- Only target cells in target organs with specific receptors for the hormone respond to that hormone

Term
Peptide Hormones
Definition

- Most hormones in body are peptide hormones

- Chains of amino acids

Longer chains are called protein hormones

- E.g. human growth hormone

Term
Steroid Hormones
Definition

- Type of lipid (fatty substance/energy supply) derived from cholesterol

- E.g. testosterone

 

Term
Biogenic Amines
Definition

- Small molecules produced by altering the structure of a specific amino acid

- E.g. thyroid hormone

Term
Negative Feedback Loop
Definition

- Return to homeostasis

- A stimulus starts a process

- Eventually either the hormone that is secreted or a product of its effects causes the process to slow down or turn off

- Many hormonal systems work by negative feedback mechanisms

Term
Positive Feedback Loop
Definition

- A stimulus starts a process which accelerates

- Either to ensure that the process continues to run, or to speed up the activities of the process

- Few hormonal systems work by positive feedback mechanisms

- E.g. Lactation from the mammary glands

Term
Pituitary Gland
Definition

- Anterior and posterior lobes

- Located in sella turcica of sphenoid bone

- Attached to inferior surface of hypothalamus via the infidibulum (pathway between hypothalamus and pituitary)

- Carries axons from the nuclei located in the hypothalamus

Term
Pituitary Gland- Hypothalamic-Pituitary Tract
Definition

- Axons from hypothalamic nuclei travel through the infundibulum to innervate posterior lobe of the pituitary gland (action potential- nerve impulse)

-Homones are then released in response to action potentials from the hypothalamus

Term
Hormones produced by the hypothalamus and stored in pituitary
Definition

- Antidiuretic hormone (ADH)- stimulates water reabsorption in the kidney

- Oxytocin- stimulates uterine contraction and milk letdown

Term
Pituitary Gland- Anterior lobe (adenohypophysis)
Definition
- Pars intermedia produces, stores, and secretes MSH (melanin control)
Term
Pituitary Gland- Hypothalamic-hypophyseal portal system
Definition

- Capillaries in hypothalamus pick up releasing factors (RF) from the hypothalamus

- Capillaries unite to form a portal vein; carries RFs to anterior lobe

- Each RF is secific to a hormone of adenohypophysis and controls release of that hormone 

Term
Hormones of the Anterior Pituitary
Definition

- TSH

- ACTH

- FSH

- LH

- Prolactin

- GH

- MSH

Term
TSH
Definition
- Targets the thyroid gland; stimulates the release of thyroid hormone (e.g. thyroxine)
Term
ACTH
Definition
- Targets the adrenal gland; stimulates the release of corisol (metabolism)
Term
FSH
Definition
- Targets the ovaries and testes; stimulates follicles development and spermatogenesis
Term
LH
Definition
- Targets ovary and testes; stimulates ovulation and testosterone production
Term
Prolactin
Definition
- Targets the mammary glands; stimulates galactopoiesis
Term
GH
Definition
- Targets various body tissues; stimulate growth
Term
MSH
Definition
- Targets integument; stimulates melanin production
Term
Thyroid Gland
Definition

- 2 lobes lying either side of the trachea just inferior to the thyroid cartilage of the larynx

- Joined across the midline by the isthmus (bridge)

- Secrets thyroxine and triiodothyronine

- Iodine that triggers body cells to increase metabolism

- Calcitonin- hypocalcemic agent that decreases osteoclast activity (decrease blood calcium)

Term
Goiter
Definition

- Idodine deficiency that restricts synthesis of thyroid hormones

- Iodized salt marketed during the 1920's in response to deficiencies endemic to parts of the U.S. (soils with inadequate iodine=less iodine in foods)

Term
Parathyroid Glands
Definition

- Two glands located on the posterior surface of each thyroid lobe (4 total)

- Secretes parathormone (extra calcium in blood/kidney)

- Hypercalcemic agent that acts on bone and the kidney

Term
Adrenal Gland
Definition

- Gland located at the superior pole of each kidney

- Cortex is composed of:

- Zona glomerulosa (secretes aldosterone; hypernatremic and hypokalemic agent that targets the kidney- salt)

- Fasciculata (secretes cortisol; aids in coping with stress and targes various body cells- sugar)

- Reticularis (secretes sex steroids - androgens, estrogens- sex)

- Adrenal medulla (secrete epinephrine, norepinephrine, and dopaine that have varying effects and target organs)

Term
Pancreas
Definition

- Gland closely associated with the upper GI

- Secretory units: Islets of Langerhans scattered throughout the pancreas secretions

- Insulin- beta cells; hypoglycemic agent; targets adipose tissue, liver and skeletal muscle- elevate sugar levels

- Glucagon- alpha cells; hyperglycemic agent; targets liver and adipose- lowers sugar levels

Term
Ovaries
Definition
- Located in the pelvis, lateral to uterus, suspended within the broad ligament
Term
Ovaries secrete: estrogen (estradiol)
Definition
- Follicular maturation and development of 1 and 2 degree sex characteristics
Term
Ovaries secrete: Progesterone
Definition
- Growth and maintenance of endometrium of the unterus
Term
Testes
Definition

- Testes (testicles) are suspended within the scrotum

- Interstitial cells of Leydig located within semiferous tubules

Term
Testes: secrete Testosterone
Definition
- Sperm maturation and development of 1 and 2 degree sex characteristics
Term
Thymus
Definition

- Located between sternum and pericardial sac

- Largest at puberty and regresses thereafter

Term
Thymus: Secretes Thymosin
Definition
- Stimulates maturation of Tlymphocytes
Term
Pineal
Definition

- Part of epitalamus of brain

- Secretes melatonin which regulates circadian rhythms

- Day/night-wake/sleep cycles

Term
Kidney
Definition

- Secretes renin

- Released to regulate the body's salt and water balance, and blood volume

- Secretes erythropoietin

- Critical for the formation of red blood cells by the bone marrow

Term
Stomach and Small Intestine
Definition

- Secrete gastrin, secretin, and cholecystokinin

- Aid in gastric motality

- E.g., regulating gastric acid levels, secretion of pancreatic digestive enzymes, release of bile

Term
Placenta
Definition

- Human chorionic gonadotropin

- Maintains progesterone levels to maintain pregnancy

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