Wingerd Chap 10 Endocrine

mdlewis34's version from 2015-06-20 01:26

Composition of Endocrine System - Concept 1

Question Answer
How does Endocrine system work?Endocrine system maintains homeostasis by releasing hormones and provide slow, but long lasting control.
Exocrine GlandSecrete products into ducts that transport the products into body cavities.
Endocrine GlandSecrete products into extracellular space surrounding the secretory cells (ductless glands)
Primary endocrine glands of the body and their locations.Pituitary gland - beneath the brain: Thyroid and Parathyroid glands - in the neck; Adrenal glands - on top of each kidney, the pancreas, and behind the stomach; Sex glands - testes in males, ovaries in females.
Minor role endocrine glandsPineal gland - in the brain; Thymus gland - above the heart
What happens when a hormone unites with receptor on target cell membrane?May change the rates of enzyme activities, secretion, protein synthesis or rates at which materials are transported.

Water-soluble Hormones - Concept 2

Question Answer
Water Soluble HormonesRelease in minute quantities, have an effect only on a particular type of cell, cannot pass through lipid cell membrane unassisted.
What is a target cell?Special protein molecules in their cell membrane that serve as receptors that recognize and bind to specific hormones.
What is the second messenger system?A signal is passed across membrane barrier.
Describe the role of cyclic AMPThe compound used by the 2nd messenger system.
What is the first messenger system?The hormone.
What protein is activated when a hormone binds to the membrane receptor?The membrane hormone activated is G protein which 'hands the baton' on to adenylate cyclase.
What is the role of adenylate cyclase?Adenylate cyclase converts ATP into cAMP, then cAMP acts the second messenger diffusing through the cell to initiate a cascade of chemical rxns that activate enzymes called protein kinases.
What does protein kinase do?Protein kinases activate other proteins which react with other molecules to induce changes in the cell.
Why is the second messenger system called an enzymatic cascade?A single hormone triggers a single enzyme, which catalyzes hundreds of rxns.

Lipid-soluble Hormones - Concept 2

Question Answer
What are lipid-soluble hormones?Mainly steroid hormones that can diffuse directly through the target cell.
What do they do in the cell?They bind to a protein receptor located within the cytoplasm and that complex binds to DNA to 'turn on' the synthesis of special protein molecules.
The synthesis of what materials within a cell is stimulated by steroid hormones?Includes aldosterone, cortisol, testosterone, estrogen and thryroxine - may stimulate or inhibit metabolic pathways.

Prostaglandins - Concept 2

Question Answer
What are prostaglandins?Hormone-like lipid soluble chemicals that are produced by many organs and have regulating effects on cells.
Why are prostaglandins called local hormones?Because they act on cells within close proximity of their site of release.
What is the function of prostaglandins?Stimulate or inhibit the formation of cAMP and hormones that use cAMP as a second messenger.
What are the effects of prostaglandins?Some reduce blood pressure, open airways by causing smooth muscles to relax, stimulate smooth muscle, cause fever inflammation and pain.

Hormonal Control - Concept 2

Question Answer
What is feedback control of hormones?Chemical signals in the bloodstream cause endocrine glands to adjust its rate of secretion.
How do negative feedback systems work?When hormones reach a certain level in the blood either the hormone itself or chemicals provide a response working in the opposite direction of the stimulus.
What is an example of a negative feedback system?PTH released by the parathyroid gland stimulates the release of Ca ions from the bones. A high blood calcium level provides a stimulus to the parathyroid gland to stop production of PTH so high chemical levels in the blood inhibits further hormone production.
How do positive feedback systems work?Positive feedback systems by causing a response in the same direction as the stimulus. They tend to by unstable and uncommon.
What is an example of a positive feedback system?Oxytocin (OT) release by the pituitary stimulates contractions during childbirth which stimulates more oxytocin release until birth is accomplished.

Pituitary Gland - Concept 3

Question Answer
Where is the pituitary gland (PG) located and what does it do?Base of the brain in a bony depression formed by sella turica of the sphenoid bone, and attached to the hypothalamus by the infundibulum.
Why is the PG attached to the hypothalamus?The hypothalamus regulates the secretion of hormones by the pituitary gland which in turn controls the activities of several other glands.

Anterior Lobe of PG - Concept 3

Question Answer
What does the anterior lobe of the pituitary gland do?Its glandular epithelium is composed of 5 different types of secretory cells that release 6 types of hormones.
What part of the brain controls the hormones the pituitary makes?The hypothalamus controls the pituitary with releasing hormones which either stimulate or inhibit the release of anterior lobe hormones.
What are the 6 hormones released by the pituitary?Growth hormone (GH), Thyroid-stimulating hormone (TSH), Adrenocorticotropic Hormone (ACTH), Follicle-stimulating hormone (FSH), Luteininzing hormone (LH), and Prolactin (PL)
What do each of the 6 released hormones target?GH - various tissues, including liver to convert glycogen to glucose; TSH - thyroid, TSH is tropic hormone because it stimulates the thyroid to 2 more hormones, regulation of cell metabolism; ACTH - adrenal cortex, stress affects its release; FSH and LH - ovaries/testes, gonadotropic hormone because it targets gonads, LH w/estrogen stimulates release of egg; PL - secretion and ejection of breast milk.

Posterior Lobe of PG - Concept 3

Question Answer
What does the posterior lobe of the pituitary do?It is really an extension of the hypothalamus and mainly neuroglial cells that supports axons - does not produce hormones.
What do the cell bodies of the posterior lobe produce?Referred to as neurosecretory cells because they produce oxytocin and anti-diuretic hormone; the hormones are packaged in vesicles and sent to the posterior lobe for storage.
What is the function of Oxytocin (OT)?Smooth muscle contraction of uterus and milk ducts, male function unknown.
What is the function of Anti-diuretic hormone (ADH)?Causes a decrease in urine output and increase in body fluid volume (osmotic pressure in bloodstream).
How does ADH effect blood pressure?It is a vasopressin which means it elevates blood pressure.

Thyroid and Parathyroid Glands - Concept 4

Question Answer
What do the thyroid gland (TG) and the parathyroid (PTG) do?The thyroid gland regulates body metabolism, and both glands manage calcium and phosphate ion levels in body fluids.
Where is the thyroid look like and where is it located?Shaped like butterfly or shield, located lightly below larynx in front of trachea - 2 lobes connect by isthmus.
What are the hollow ball-shaped compartments in the TG called?Thyroid follicles
What is the purpose of the thyroid follicles?The follicular cells produce and secret thyroxine or T4 and triiodothyronine or T3.
What do the cells between the follicles do?Parafollicular cells produce a 3rd hormone called calcitonin which helps maintain calcium and phosphate levels in the bloodstream.

T4 and T3 - Concept 4

Question Answer
What is the function of T4 and T3?Important roles in metabolism and growth. together they stimulate the rate of metabolism, promote protein synthesis, increase the rate of glucose uptake, promote lipid metabolism, and accelerate actions of the nervous system.
How are concentrations regulated?Negative feedback between the hypothalamus and anterior lobe of the PG- thyroid hormone levels in the blood drop, hypothalamus secretes a releasing hormone (TRH) which triggers PG to secrete TSH.

Calcitonin (CT) - Concept 4

Question Answer
What is the function of CT?Reduces Ca and PO4 levels in blood.
How and why control these ions?Functions with PTH release by PTG to regulate concentrations. Ca conc. must be kept within narrow limits for normal nerve and muscle function, and bone.
What is the effect of CT?Primary effect is the inhibition of bone-dissolving cells and stimulates the excretion of calcium and phosphate ions by kidneys.

Parathyroid Glands (PTG) - Concept 4

Question Answer
What are PTG's?4 or 5 pea shaped masses of glandular epithelium embedded within the posterior thyroid gland. Secrete parathyroid hormone (PTH).
What role does PTH play in the body?Maintains blood levels of Ca and PO4 which opposes CT release by the TG - prompts osteoclasts to break done bone matrix (bone resorption). Also stimulates conversion of precursor molecules to form vitamin D in kidneys.

Adrenal Glands - Concept 5

Question Answer
What do adrenal glands look like?
Where are adrenal glands located?
What are the 2 parts of the adrenal glands?

Adrenal Medulla