Exam 5 Review:  Chapter 16:  General Endocrine Terminology

endocrine gland - A ductless gland, e.g., the thyroid or the pituitary glands, which produces one or more hormones which will be released into the bloodstream to be distributed body wide in order to interact with their target cells, tissues, and organs.

endocrine system - The glands and parts of glands which produce endocrine secretions, i.e., hormones, which help to integrate and control bodily metabolic activity and physiological functions; e.g.,. the pituitary, thyroid, parathyroids, adrenals, pancreatic islets of Langerhans, ovaries, and testes.

endocrinology - The science dealing with the endocrine glands and their diseases.

hormone = endocrine = endocrine substance - a regulatory molecule, produced by an endocrine gland or endocrine or neuroendocrine cell, which is secreted into the blood stream to circulate widely in the body to interact with their target cells, tissues, and organs in order to integrate and control their metabolic activity and physiological functions; hormones may be made from cholesterol, the steroids, or from amino acids, the amine, peptide and protein hormones.

neuroendocrine system - Complex control systems in the body where the nervous system and one or more endocrine organs or tissues cooperate closely to regulate and control the metabolic activity and physiological functions of specific target cells, tissues, or organs; e.g., the cooperation between the hypothalamus and each lobe of the pituitary gland, and the cooperation between the sympathetic division of the ANS and the adrenal cortex.

target cells - Cells which are acted upon selectively by a specific agent, e.g., a hormone, local hormone, neurotransmitter, a drug, or a virus; target cells for neurotransmitters have cell surface receptors which bind to the neurotransmitter;  target cells for hormones have cell surface receptors or cytoplasmic receptors which bind to the hormones.

cell surface receptor - An integral or peripheral membrane protein of a target cell's plasmalemma which has an affinity for and will bind noncovalently and reversibly with a specific molecule, which may be a part of a hormone, local hormone, neurotransmitter, a drug, or a virus; such membrane protein receptors for hormones and local hormones generally activate one or more internal second messenger systems to effect the regulatory change controlled by the arrival of the hormone or local hormone.

cytoplasmic receptor - A cytoplasmic protein of a target cell which has an affinity for and will bind noncovalently and reversibly with a specific molecule, which may be a part of a hormone, local hormone, neurotransmitter, a drug, or a virus; cytoplasmic receptors for hormones, usually steroid hormones or thyroid hormones, generally form a complex which migrates to the nucleus to bind with specific portions of a DNA molecule, i.e., a chromosome, in order to activate one or more genes which will be translated to form new proteins which will effect the regulatory change controlled by the arrival of the hormone.

down-regulation - A reduction in the number of receptors for a control substance, e.g., a hormone, local hormone, neurotransmitter, or a drug, in response to a prolonged excess of the control substance; this is an internal adjustment which usually helps restore homeostasis in a disease state.

up-regulation - An increase in the number of receptors for a control substance, e.g., a hormone, local hormone, neurotransmitter, or a drug, in response to a prolonged decrease of the control substance; this is an internal adjustment which usually helps restore homeostasis in a disease state.

Compare and Contrast:

1.  nervous system to endocrine system regulation of homeostasis.

 

Nervous System

Endocrine System

1.  rapid control 2.  control via action potentials = nerve impulses propagated along nerve fibers 3.  chemical signal molecule is a neurotransmitter released locally at the site of specific effector cells/tissues which have receptors for the neurotransmitter 4.  each nerve impulse acts briefly (msecs/seconds) although control can be sustained by continuing to send more nerve impulses 5.  response by the effectors is of relatively short duration (seconds/minutes) from a single nerve impulse 6.  hypothalamic control exerted via autonomic nervous system

1.  slower control 2.  control via hormones released into body fluids which must be circulated through the circulatory system (bloodstream) to all parts of the body 3.  chemical signal molecule is a hormone released widely throughout the bloodstream and body fluids, although responses will occur locally only at the site of specific effector cells/tissues which have receptors for the hormone 4.  each hormone molecule somewhat longer (seconds/hours/days) and target tissues may respond longer still; control can be sustained by continuing to send more hormone molecules 5.  response by the effectors is of relatively long duration (seconds/minutes/hours/days/weeks/months) from a single nerve impulse 6.  hypothalamic control exerted via pituitary hormones

List and Describe:

1.  the two main chemical categories of hormones (endocrines).

 

main chemical categories

amino acid based lipid based

important chemical subcategories

amines peptides proteins steroids (cholesterol-based) eicosanoids (arachidonic acid- based)

2.  three ways in which hormones interact.

 

permissiveness - one hormone allows another hormone to cause an effect

synergism - when the effect of two hormones acting together is great than the sum of the effects produced when each hormone acts alone

antagonism - when two hormones exert opposite effects on a given target cell/tissue (a common form of negative feedback control)

3.  three examples of hormone released under (a) humoral control/autocontrol, (b) nervous system control, and (c) endocrine control.

 

Mechanism Of Control Of Hormone Release	Example Hormones [not a complete list]
humoral control/autocontrol	all hypothalamic releasing & inhibiting hormones glucagon & insulin (thyrocalcitonin) parathyroid hormone = parathormone aldosterone atrial natriuretic peptide (ANP)
nervous system control	oxytocin antidiuretic hormone (ADH) = vasopressin norepinephrine & epinephrine = adrenalin
endocrine control	all anterior pituitary hormones (hGH, TSH, ACTH, FSH, LH, PR) thyroid hormones (T3 & T4) glucocorticoids (cortisone, hydrocortisone, cortisol) estrogens & progesterone androgens (testosterone)

4.  at least two examples of antagonistic hormone interactions.

 

insulin lowers blood glucose while glucagon (and the other "insulin antagonists) elevates blood glucose

(thyro)calcitonin lowers blood calcium while parathyroid hormone elevates blood calcium

aldosterone lowers blood potassium and elevates blood sodium while atrial natriuretic peptide/hormone elevates blood potassium and lowers blood sodium

growth hormone releasing hormone (GHRH) increases anterior pituitary output of human growth hormone (hGH) while growth hormone inhibiting hormone (GHIH) [= somatostatin] lowers  anterior pituitary output of human growth hormone (hGH)

thyroid releasing hormone (TRH) increases anterior pituitary output of thyroid stimulating hormone (TSH) while growth hormone inhibiting hormone (GHIH) [= somatostatin] lowers anterior pituitary output of thyroid stimulating hormone (TSH)

an unidentified prolactin releasing hormone (PRH) increases anterior pituitary output of prolactin while dopamine = prolactin inhibiting hormone (PIH) lowers anterior pituitary output of prolactin

5.  three fundamental ways in which hormone secretion is regulated.

 

humoral control/autocontrol	endocrine cells themselves check the level of some substance in the blood and respond to changes with a change in hormone secretion, e.g., pancreatic islet cells monitor blood glucose to adjust output of insulin and glucagon
nervous system control	the hypothalamus regulates the output of posterior pituitary = neurohypophysis hormones (ADH = vasopressin and oxytocin) and autonomic stimulation of the adrenal medulla leads to epinephrine = adrenalin and norepinephrine release
hormonal control	neurohormones from the hypothalamus stimulate the anterior pituitary = adenohypophysis to release its hormones; many of those hormones (e.g., TSH, ACTH, FSH, LH) then regulate the output of other endocrine glands

12. the hormone(s) secreted by each of the main endocrine glands, their targets and their effects.

 

Endocrine Gland	Hormone(s)	Target Cell(s)/Organ(s)	Action(s)
Anterior Pituitary	human growth hormone (hGH) thyroid-stimulating hormone (TSH) follicle-stimulating hormone (FSH) luteinizing hormone (LH) prolactin (PRL) adrenocorticotropic hormone (ACTH) melanocyte stimulating hormone (MSH)	(hGH) all body cells (TSH) thyroid follicular cells (FSH) ovary & ovarian follicles (LH) ovary & ovarian follicles (PRL) mammary glands (ACTH) adrenal cortex (MSH) melanocytes	(hGH) growth, protein synthesis (TSH) stimulate T3 & T4 release (FSH) stimulate follicular growth and estrogen production (LH) stimulate ovulation and progesterone production (PRL) stimulate mammary gland growth and milk production (ACTH) stimulate adrenal cortical hormone production (MSH) little action in humans
Posterior Pituitary	oxytocin (OT)     antidiuretic hormone (ADH) = vasopressin	myometrium of uterus mammary ducts kidney tubules blood vessel smooth muscle	smooth muscle contractions for labor & delivery smooth muscle contractions & milk letdown conserve water from the urine increasing blood pressure vasoconstriction increasing blood pressure
Thyroid	thyroxine = tetraiodothyronine = T4 triiodothyronine = T3 calcitonin = thyrocalcitonin	all body cells   osteoclasts	increase metabolic activity & thermogenesis especially by skeletal muscle inhibit osteoclastic activity which lowers blood calcium levels
Parathyroid	parathyroid hormone = parathormone (PTH)	osteoclasts   small intestine kidney tubules	stimulate osteoclastic activity which elevates blood calcium levels increase calcium absorption from a meal increase calcium absorption from the urine; add phosphate ions to the urine
Adrenal Cortex	mineralocorticoids:  aldosterone     glucocorticoids: cortisol, etc.   gonadocorticoids:  estrogens, androgens	kidney tubules   most body cells immune cells ovary & testis and tissues of secondary sexual characteristics	increase sodium and H2O absorption from the urine; add potassium ions to the urine increasing blood glucose levels and fat catabolism various anti-inflammatory properties see ovary & testis below minor effects from low production levels
Adrenal Medulla	epinephrine = adrenalin norepinephrine	all visceral effectors with adrenergic receptors	same response as by stimulation from the Sympathetic Division of the ANS
Pancreas	glucagon     insulin	liver   liver most tissue cells other than nervous tissue	glycogenolysis elevate blood glucose liver - glycogenesis all target cells - take up glucose from the blood and use it for energy (adipose cells covert glucose to stored fat)
Ovary	estrogen   progesterone   inhibin   relaxin	uterus, breasts, tissues of secondary sexual characteristics uterus, breasts, tissues of secondary sexual characteristics anterior pituitary gland cervix and pelvic ligaments	supports reproductive functions supports reproductive functions negative feedback control of FSH softens cervix and relaxes pelvic ligaments to assist in labor and delivery
Testis	androgens:  testosterone, etc.	testes and tissues of secondary sexual characteristics	supports reproductive functions

17.  three disease states caused by hyposecretion of a hormone.

 

Hormone	Hyposecretion Disease State
human growth hormone (hGH) thyroid-stimulating hormone (TSH) adrenocorticotropic hormone (ACTH)	pituitary dwarfism hypothyroidism (cretinism in infants, myxedema in adults) hypoadrenalism "Addison's disease"
antidiuretic hormone (ADH) = vasopressin	diabetes insipidus
thyroxine = tetraiodothyronine = T4 triiodothyronine = T3	hypothyroidism (cretinism in infants, myxedema in adults)
glucocorticoids: cortisol, etc. (mineralocorticoids:  aldosterone)	hypoadrenalism "Addison's disease"
insulin	diabetes mellitus
estrogen  progesterone	amenorrhea & infertility
androgens:  testosterone, etc.	infertility

18.  three disease states caused by hypersecretion of a hormone.

 

Hormone	Hypersecretion Disease State
human growth hormone (hGH) thyroid-stimulating hormone (TSH) adrenocorticotropic hormone (ACTH)	pituitary gigantism hypothyroidism Cushing's Disease
thyroxine = tetraiodothyronine = T4 triiodothyronine = T3	hyperthyroidism
glucocorticoids: cortisol, etc. gonadocorticoids:  androgens (less involved:  estrogens)	Cushing's Disease congenital adrenal hyperplasia
epinephrine = adrenalin norepinephrine	hypertension (pheochromocytoma)

20.  the hormone(s) secreted by each of the main endocrine glands, the chemical class of each hormone, and the trigger(s) for each hormone's release

.

Endocrine Gland	Hormone(s)	Chemical Class	Trigger(s) For Each Hormone's Release
Anterior Pituitary	human growth hormone (hGH) thyroid-stimulating hormone (TSH) follicle-stimulating hormone (FSH) luteinizing hormone (LH) prolactin (PRL) adrenocorticotropic hormone (ACTH) melanocyte stimulating hormone (MSH)	Protein Protein Protein Protein Protein Protein Protein	GHRH TRH GnRH GnRH PRH(?), suckling reflex CRH, glucocorticoid levels (?)
Posterior Pituitary	oxytocin (OT) antidiuretic hormone (ADH) = vasopressin	Peptide Peptide	uterine smooth muscle stretching during labor & delivery; suckling reflex dehydration & increasing blood osmolarity
Thyroid	thyroxine = tetraiodothyronine = T4 triiodothyronine = T3 calcitonin = thyrocalcitonin	Amine   Protein	TSH & hypothermia & periods of growth & pregnancy in females   an increase in blood calcium levels
Parathyroid	parathyroid hormone = parathormone (PTH)	Protein	a decrease in blood calcium levels
Adrenal Cortex	mineralocorticoids:  aldosterone   glucocorticoids: cortisol, etc. gonadocorticoids:  estrogens, androgens	Steroid   Steroid Steroid	dehydration, decreased plasma sodium, increased plasma potassium, angiotensisn I & II and (minor role:  ACTH) ACTH (minor role:  ACTH)
Adrenal Medulla	epinephrine = adrenalin norepinephrine	Amines	stimulation from the Sympathetic Division of the ANS
Pancreas	glucagon insulin	Protein Protein	a decrease in blood glucose levels an increase in blood glucose levels
Ovary	estrogen progesterone inhibin relaxin	Steroid Steroid Protein Protein	FSH & (minor role:  LH) LH & (minor role:  FSH) an increase in blood estrogen levels anticipation of labor and delivery
Testis	androgens:  testosterone, etc.	Steroid	LH = ICTH

Diagram:

1.  the antagonistic hormonal control of:

  [Note:  include hormone actions at specific target organs/tissues.]

    a.  plasma glucose levels

This first figure (below) provides the basics of the antagonistic control.

This second figure (below) provides the details on insulin's actions.

This third figure (below) provides the details on glucagon's actions.

    b.  plasma calcium levels

    c.  plasma sodium and potassium levels
 

The question emphasizes the antagonistic hormonal control of plasma sodium and potassium levels.  The figure (below) contains additional background information.  Therefore, you should focus on the interplay between aldosterone, angiotensin I & II, and atrial natriuretic peptide -- they are the main antagonists.

Follow this link for a preview of how some of this endocrine control will be presented again in discussions of kidney function and the homeostasis of water balance in the body.