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What are the functions of the Endocrine ?
- 1. sexual differentiation
- 2. Growth and development
- 3. Continous maintenance of the body's internal enviroment
- chemical messengers synthesized by endocrine glands and released into circulation
- Usually work on negative feedback
- act on target cells
- Have both a direct effect or permissive effect
- Receptors for hormones may be located on the plasma membrane or in the intracellular compartement of a target cell
Water Soluble Hormones:
act as first messangers binding to receptors on the cells plasma membrane. The signals initiated by hormone receptor binding are then transmitted into the cell by the action of second messangers
Lipid Soluble Hormones
- including steriod and thyroid hormones
- cross the plama membrane by diffusion and directly into the cell nucleus and bind to neuclear receptors. Rapid respnses of steroid hormones may be mediated by plasma membrane receptors
The pituitary gland:
consists of anterior and posterior portions and is contected to the CNS via the hypothalamus
What is the function of the hypothalamus in relation to the anterior pituitary
it regulates the anterior pituitary function by secreting releasing hormones and releasing factors into the portal circulation.
- 1. Prolactin inhibiting factor (PIF)- inhibits prolactin secretion
- 2. Thyrotropin releasing hormone (TRH)- affects the release of thuroid hormones
- 3. Gonadotropin releasing hormone (GnRh)- realseses adrenocorticotropc hormone (ACTH), endorphins, and substance P (which inhibits ACTH release and stimulates release of a variety of other hormones)
What does the posterior pituitary secretet:
ADH and oxytocin
What are the hormones released by the anterior pituitary?
- melanocyte stimulating hormone (MSH)
- somatotropic hormones (growth hormones and prolactin)
- Follicle Stimulating hormone (FSH)
- Luitenizing Hormone (LH)
- Thyroid Stimulating Hormone (TSH)
How is TSH regulated?
it is regulated by thyroid releasing hormone (TRH) through a negative feedback loop that involves the anterior pituitary and hypothalamus
T3 and T4:
when released into circulation they are bound by carrier proteins in teh plasma which store these hormones and provide a buffer for rapid changes in hormone levels. The free form is the active form.
What do Thyroid hormones do?
alter protein synthesis and have a wide range of metablic effects on proteins, carbs, lipids, and vitamins. It also effects heat production and cardiac function
Parathyroid Hormone (PTH):
In bone PTH causes bone breakdown and resorption. In the kidney it increases reabsorption of calcuim and decreases reabsorption of phosphorus and bicarbonate
Iselts of Langerhans (Pancreas):
- 1. Alpha - Glucagon
- 2. Beta- Insulin
- 3. Delta- somatostatin which inhibits glucagon and insulin secretion
- 4. F Cells- pancreatic polypeptide
- Cortex - releases steriod hormones
- Medulla - which secretes catecholamines
The Adrenal Cortex
- releases steriod hormones which are synthesized from cholesterol.
- These include glucocorticoids, mineralocorticoids, and adrenal androgens and estrogens.
directly affect carb metabolism by increasing blood glucose concentration through gluconeogenesis in the liver and by decreasing use of glucose. They also inhibit immune and inflamatory response
- is a gluccocorticoid, which is necessary for the mainteance of life and for protection from stress. It is regulated by the hypothalamus and anterior pituitary
- ist is stimulated by ACTH (which is stimulated by CRH) which binds to receptors in the adrenal cortex and activatees intracellular mechanisms (cyclic AMP) and leads to its release.
regulates sodium concentration through the RAS.
Adrenal Medulla secretes:
catecholamines such as epinephrine and norepinephrine. Their release is stimulated by the sympathetic nervous system, ACTH, and gluccocorticoids.