A&P II Endocrine system part 3

Where are the adrenal glands located?

Paired, pyramid-shaped organs atop kidneys =Also referred to as suprarenal glands

Which cells of the pancreas produce the pancreatic hormones?

Pancreatic islets (islets of Langerhans) contain endocrine cells. Insulin is produce by beta cell of the pancreatic islets. Glucagon is produce by alpha cells of the pancreatic islets.

Graves' disease

1. Autoimmune disease: body makes abnormal antibodies directed against thyroid follicular cells 2. Antibodies mimic TSH, stimulating TH release 3. Symptoms include elevated metabolic rate, sweating, rapid and irregular heartbeats, nervousness, and weight loss despite adequate food =Exophthalmos may result: eyes protrude as tissue behind eyes becomes edematous and fibrous 4. Treatments include surgical removal of thyroid or radioactive iodine to destroy active thyroid cells =Kill the thyroid cell by radio

List the glucocorticoids. What are their functions?

1. Cortisol (hydrocortisone); only glucocorticoid in significant amounts in humans 2. Cortisone 3. Corticosterone

Factor the influence insulin release?

1. Elevated blood glucose levels: primary stimulus 2.Rising blood levels of amino acids and fatty acids 3.Release of acetylcholine by parasympathetic nerve fibers 4. Hormones glucagon, epinephrine, growth hormone, thyroxine, glucocorticoids 5.Somatostatin and sympathetic nervous system inhibit insulin release

How is the release of thyroid hormone controlled by negative feedback?

1. Falling TH levels stimulate release of thyroid-stimulating hormone (TSH) =Rising TH levels provide negative feedback inhibition on TSH =TSH can also be inhibited by GHIH, dopamine, and increased levels of cortisol and iodide 2. Hypothalamic thyrotropin-releasing hormone (TRH) can overcome negative feedback during pregnancy or exposure to cold, especially in infants

What hormones are produced by the adrenal cortex?

1. Mineralocorticoids: Aldosterone, Renin-angiotensin-aldosterone mechanism, Plasma concentration of K+, ACTH, and Atrial natriuretic peptide (ANP) 2. Glucocorticoids: Cortisol (hydrocortisone), Cortisone, Corticosterone 3. Gonadocorticoids (adrenal sex hormone): (Influence metabolism of most cells and help us resist stressors. Keep blood glucose levels relatively constant. Maintain blood pressure by increasing action of vasoconstrictors)

What are the functions of mineralcorticoids?

1. Regulate electrolyte concentrations (primarily Na+ and K+) in ECF (regulate mineral) =Importance of Na+: affects ECF volume, blood volume, blood pressure, and levels of other ions (K+, H+, HCO3− and Cl−) =Importance of K+: sets resting membrane potential of cells

Aldosterone is secreted in response to decreasing blood volume and blood pressure. Describe the 4 mechanisms that regulate aldosterone secretion.

1. Renin-angiotensin-aldosterone mechanism 2. Plasma concentration of K+ 3. ACTH 4. Atrial natriuretic peptide

myxedema

1. Symptoms include low metabolic rate, thick and/or dry skin, puffy eyes, feeling chilled, constipation, edema, mental sluggishness, lethargy 2. If due to lack of iodine, a goiter may develop =Lack of iodine decreases TH levels, which triggers increased TSH secretion, triggering thyroid to synthesize more and more unusable thyroglobulin =Thyroid enlarges

Regulation of secretion of cortisol

=Cortisol is released in response to ACTH --ACTH released in response to corticotropin-releasing hormone (CRH) --CRH released in response to low cortisol levels --Increased cortisol levels inhibit ACTH and CRH through negative feedback =Cortisol secretion cycles are governed by patterns of eating and activity =Acute stress (infection, physical or emotional trauma) interrupts cortisol rhythm =CNS can override cortisol inhibition of ACTH and CRH, leading to more cortisol secretion

Where are the parathyroid glands located?

Four to eight tiny yellow-brown glands embedded in posterior aspect of thyroid

What hormone is produced by the parathyroid gland and what are its functions?

Hormons: 1. Contain oxyphil cells (function not clear) and parathyroid cells that secrete parathyroid hormone (PTH), or parathormone 2. PTH is most important hormone in Ca2+ homeostasis =Secreted in response to low blood levels of Ca2+ =Inhibited by rising levels of Ca2+ 3. Target organs are skeleton, kidneys, and intestine Functions to: 1. Stimulate osteoclasts to digest bone matrix and release Ca2+ to blood 2. Enhances reabsorption of Ca2+ and secretion of phosphate (PO43-) by kidneys 3. Promotes activation of vitamin D by kidneys, which leads to increased absorption of Ca2+ by intestinal mucosa

Describe homeostatic imbalances of thyroid hormone.

Hyposecretion = lead to myxedema and cretinism Hypersecretion= Graves' disease

What hormones are responsible for the development of secondary sex characteristics in males and females? What glands produce these hormones?

In women Estrogen and progesterone produce by ovaries. In male it is testosterone produce by testes.

Describe the function and regulation of calcitonin.

Regulation: Calcitonin is involved in helping to regulate levels of calcium and phosphate in the blood, opposing the action of parathyroid hormone. 1. Produced by parafollicular (C) cells in response to high Ca2+ levels 2. Antagonist to parathyroid hormone (PTH) 3. No known physiological role in humans at normal physiological levels, but at higher-than-normal doses: a. Inhibits osteoclast activity and prevents release of Ca2+ from bone matrix c. Stimulates Ca2+ uptake and incorporation into bone matrix

What are the functions of glucagon and insulin?

The pancreas releases glucagon when the concentration of glucose in the bloodstream falls too low. Glucagon causes the liver to convert stored glycogen into glucose, which is released into the bloodstream. High blood-glucose levels stimulate the release of insulin.

What are the functions of corticosteroids?

This area of adrenal gland produces over 24 different hormones collectively Function: suppress inflammation and immunity and assist in the breakdown of fats, carbohydrates, and proteins, or as. mineralocorticoids (salt retaining) that regulate the balance of salt and water in the body.

factor the influence glucagon release?

Triggered by decreased blood glucose levels, rising amino acid levels, or sympathetic nervous system

action of cortisol

a. Cortisol causes increase in blood levels of glucose, fatty acids, and amino acids b. Prime metabolic effect is gluconeogenesis, formation of --glucose from fats and proteins --Encourages cells to use fatty acids for fuel so glucose is "saved" for brain c. Other function is to enhance vasoconstriction --Causes rise in blood pressure to quickly distribute nutrients to cells d. Excessive levels of glucocorticoids: --Depress cartilage and bone formation --Inhibit inflammation by decreasing release of inflammatory chemicals --Depress immune system --Disrupt normal cardiovascular, neural, and gastrointestinal functions e. Glucocorticoid drugs can control symptoms of many inflammatory diseases (arthritis, allergies) but can also cause undesirable effects

What two hormones are released in response to stimulation of the sympathetic nervous system?

a. Epinephrine is more a stimulator of metabolic activities --Example: bronchial dilation, and blood flow to skeletal muscles and heart b. Norepinephrine has more of an influence on peripheral vasoconstriction and blood pressure

Describe Cushing's disease.

a. Hypersecretion b. Depresses cartilage/bone formation and immune system; inhibits inflammation; disrupts neural, cardiovascular, and gastrointestinal function c. Causes: tumor on pituitary, lungs, pancreas, kidney, or adrenal cortex; overuse of corticosteroids d. Cushingoid signs: "moon" face and "buffalo hump" Treatment: removal of tumor, discontinuation of drugs

Describe Addison's disease.

a. Hyporsecretion b. Also involves deficits in mineralocorticoids c. Decrease in glucose and Na+ levels d. Weight loss, severe dehydration, and hypotension e. Treatment: corticosteroid replacement therapy

What are the general functions of gonadocorticoids. What are the more potent gonadotropins?

a. adrenal sex hormone b. Weak androgens (male sex hormones) converted to testosterone in tissue cells, some to estrogens --Example: androstenedione and dehydroepiandrosterone (DHEA) c. May contribute to: --Onset of puberty and appearance of secondary sex characteristics --Sex drive in women --Source of estrogens in postmenopausal women

Describe the mechanism behind diabetes mellitus.

can be due to: =Hyposecretion of insulin: Type 1 (not producing) =Hypoactivity of insulin: Type 2 (not responding) =When blood glucose levels remain high, person feels nauseated, leading to sympathetic response ==Fight-or-flight response acts to further increase blood glucose levels =When sugars cannot be used as fuel, as in DM, fats are used, causing lipidemia: high levels of fatty acids in blood

What are the effects of hyperparathyroidism?

due to parathyroid gland tumor =Calcium leaches from bones, causing them to soften and deform =Elevated Ca2+ depresses nervous system and contributes to formation of kidney stones =Osteitis fibrosa cystica: severe form resulting in easily fractured bones

What hormone is produced by the pineal gland and what is its function? What inhibits the release of this hormone?

pineal gland cell called pinealocytes secrete melatonin. Timing of sexual maturation and puberty. Day/night cycles Physiological processes that show rhythmic variations (body temperature, sleep, appetite) Production of antioxidant and detoxification molecules in cells. bright light inhibits the productions of malatonin

Look over table 16.5 and identify the different hormones produced by organs other than endocrine glands.

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