Chapter 19: The Endocrine System

What are the functions on parathyroid hormones (PTH)?

1) Stimulates osteoclast activity 2) stimulates osteoblast activity to a lesser degree 3) reduces calcium loss in the urine 4) promotes calcium absorption in the intestine (by stimulating calcitriol production) 5) decrease PTH could result in muscle spasm.

What does the kidney produce and why?

1) The enzyme renin for blood pressure and volume regulation. 2) The peptide hormone, erythropoietin, when blood pressure or oxygen levels in the kidneys decline

How does the hypothalamus regulate endocrine and neural activity?

1) controls the output of the adrenal medulla, an endocrine component of the sympathetic division of the ANS 2) Produces two hormones of its own (ADH and oxytocin), which are released from the posterior lobe of the pituitary gland 3) controls the activity of the anterior lobe of the pituitary gland through the production of regulatory hormones (releasing hormones and inhibiting hormones)

What are the steps of negative feedback control that regulates the endocrine activity? How do the step effect stimulation?

1) endocrine cell releases its hormone in response to changes in the composition of the extracellular fluid 2) the target cell is stimulated 3) the target cell restores homeostasis This response eliminates the source of stimulation of the endocrine system

What are the two functions of somatostatin?

1) reduce the rate of hormone secretion by alpha and beta cells 2) slows food absorption and enzyme secretion in the digestive tract

What are the subdivisions of the adrenal cortex

1) the outer zona glomerulosa 2) the middle zona fasiculata 3) the inner zona reticularis

What hormones are released by the pars distalis?

1)Thyroid-stimulating hormone (TSH) 2) Adrenocorticotropic hormone (ACTH) 3) follicle-stimulating hormone (FSH) 4) Luteinizing hormone (LH)

Where do the 9 peptide hormones that the pituitary gland release go?

2 are synthesized in the hypothalamus and released at the posterior lobe of the pituitary and 7 are synthesized in the anterior lobe of the pituitary

Pancreas

A nodular organ occupying space between the stomach and small intestines. It contains both exocrine and endocrine cells.

Where do adrenal glands lie? and how many?

A single adrenal gland rests on the superior border of EACH kidney. One each kidney they are surrounded by fibrous capsule

What are the steroid hormones in the adrenal cortex called?

Adrenocortical steroids (corticosteriods)

Four cell types of pancreatic islets

Alpha Cells-produce glucagon to raise blood glucose levels Beta Cells-Secrete insulin to lower blood glucose levels Delta cells-secrete somatostatin (growth hormone-inhibiting factor) to inhibit the production and secretion of glucagon and insulin F cells-secrete pancreatic polypeptide (PP) to inhibit gallbladder contraction and regulate the production of some pancreatic enzymes.

What are the four groups hormones can be divided into based on chemical structure?

Amino acid derivatives, peptide hormones, steroids, and eicosanoids.

What do male interstitial cells produce?

Andgrogens

What do specialized muscle cells of the heart produce? When?

Atrail natriuetic peptide (ANP) and brain natriuretic peptide (BNP) when blood pressure or blood volume becomes too much by stimulating water and sodium ion loss at kidneys to reduce blood volume.

How does insulin lower blood glucose?

By increasing the rate of glucose uptake and utilization by most body cells.

How does glucagon raise blood glucose?

By increasing the rates of glycogen breakdown and glucose synthesis in the liver.

What do C cells of the thyroid follicles produce?

Calcitonin (CT)

What is Humoral Stimuli?

Changes in the composition of extracellular fluid

What happens when production of estrogen declines too much to support ovulation?

Early menopause

Where is the thymus?

Embedded in a connective tissue mass in the thoracic cavity.

How do thyroid glands store its hormones?

Extracellularly

What happens with over production of thyroid hormone?

Grave's disease.

What does calcitonin do?

Helps decrease calcium ion concentrations in body fluids by inhibiting osteoclast activities and stimulating calcium ion excretion at the kidneys.

What is Melanocyte-stimulating hormone (MSH)?

Hormones released by the pars intermedia and stimulates melanocytes to produce melanin

Where are oocytes developed?

In follicles in the female ovary

Where is the thyroid gland located?

Inferior to the thyroid cartilage of the larynx

How is the anterior lobe of the pituitary gland subdivided?

Into the large pars distalis, the slender pars intermedia, and the pars tuberalis.

What happens in an decrease of ADH?

It causes diabetes insipidus.

What does progesterone do?

It facilitates the movement of fertilized eggs through the uterine tube to the uterus and stimulates the preparation of the uterus for implantation.

What is aldosterone?

It is a mineralcorticoids that restricts sodium and water losses at the kidneys, sweat glands, digestive tract, and salivary gland.

What happens to Renin in lung capillaries?

It is covered to angiotensin II which is a hormone that stimulates the production of aldosterone in the adrenal cortex.

What hormone is produced by sustentacular cells in the testes? What is its function?

It produces inhibin which interacts with FSH from the anterior lobe of the pituitary gland to maintain sperm production at normal levels

What does the thymus do?

It produces several hormones that stimulate the development and maintenance of normal immunological defenses.

What does the zona glomerulosa do?

It releases mineralocorticoids (MC) principally aldosterone and respondeds ti the presence of the hormone angiotensin II.

What does ADH do?

It releases the amount of water lost at the kidneys in response to a rise in the concentration of electrolytes in the blood or a fall in blood volume.

What happens if the zona fasciculata is damaged?

It results in an increase of urine volume and increased water retention.

What does the kidney secrete and when?

It secretes the steroid hormone calcitriol when parathyroid hormone is present

What does oxytocin do in men?

It stimulates prostatic smooth muscle contractions

what does oxytocin do in women?

It stimulates smooth muscle cells in the uterus and contractile cells in the mammary glands in response to stretched uterine muscles and or suckling of an infant

What does melatonin do?

Melatonin slows the maturation of sperm, eggs, and reproductive organs by inhibiting the production of FSH- and LH- releasing factors from the hypothalamus. It also may establish circadian rhythms

What is the posterior lobe of the pituitary gland called? What does it produce?

Neurohypophysis or pars nervosa and it produces ADH and oxytocin.

What do clusters of cells of endocrine pancreas form?

Pancreatic Islets

What are the secretory cells in the pineal gland called?

Pinealocytes, which synthesize melatonin

What does the zona fasciculata do?

Produce glucocorticoids (CG) specifically cortisol and corticosterone.

What does the zona reticular do?

Produce small amounts of sex hormones called androgens.

Endocrine cells in the the kidney and heart produce hormones that are important for what?

Regulation of blood pressure and blood volume, blood oxygen levels, and calcium and phosphate ion absorption.

What does growth hormone (GH or somatotropin) do?

Stimulates cells' growth and replication. GH is the only hormone to target all cells to some degree.

What does Follicle Stimulating Hormone (FSH) do?

Stimulates estrogen secretion (estradiol) and egg development in women and sperm production in men

What does Erythropoietin (EPO) do?

Stimulates red blood cell production by the bone marrow.

What does Calcitriol do?

Stimulates the absorption of both calcium and phosphate in the digestive tract

What dos prolactin (PRL) do?

Stimulates the development of the mammary glands and the production of milk

What does Adrenocorticotropic hormone (ACTH) do?

Stimulates the release of glucocorticoids by adrenal gland

What is the most important androgen? Why?

Testosterone because it promotes the production of functional sperm, maintains reproductive0tract secretory glands, influences secondary sexual characteristics, and stimulates muscle growth

What happens when a thyroid gland is stimulated by TSH?

The follicle cells reabsorb the thyroglobulin, break down the protein, and release the thyroid hormones, thyroxine (T4) and triidothyronine (T3) into the circulation.

What is the largest part of the adrenal cortex?

The middle zona fasciculate which is three quarts of the adrenal cortex.

What happens to remaining follicle cells after ovulation?

The remaining follicles within the ovary reorganize into corpus luteum?

What is the most dramatic endocrine change with advancing aging?

The rise in reproductive hormone levels at puberty and the decline in reproductive hormone levels at menopause.

How do hormones exert their effects?

They modify the activities of target cells.

Wha do principal (chief) cells produce in the parathyroid glands and what do they do?

They produce parathyroid hormones in response to lower than normal concentrations of calcium ions.

What does thymosin promote?

They promote the development and maturation of lymphocytes

What do chromatic cells secrete?

They secrete either epinephrine (75-80%) or norepinephrine (20-25%)

Why do the nervous and endocrine system work together?

To monitor and adject physiological activities for the regulation of homeostasis.

What does Thyroid Stimulating Hormone (TSH) do?

Triggers the release of thyroid hormones.

How is the thyroid gland connected?

Two lobes connected by narrow isthmus

How can endocrine activity be controlled?

by neural activity, positive feedback, or negative feedback mechanisms

What does Luteinizing hormone (LH) do?

causes ovulation and production of progenitors (pregesterone) in women and androgens (testosterone) in men

What are target cells?

cells that are sensitive to that particular hormone.

What does the adrenal medulla contain?

clusters of chromaffin cells that resemble sympathetic ganglia neurons.

What are cellular activities and metabolic reactions controlled by?

enzymes

Renin

important for blood pressure and volume regulation catalyzes the conversion of circulating angiotensinogen to angiotensin I

Corpus Luteum

left over follicles that produces a mixtures of estrogen and progestin, especially progesterone.

Exocrine pancreas

secretes an enzyme-rich fluid into the lumen of the digestive tract.