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36 Cards in this Set

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FUNCTIONS
A. to help regulate body activity through the release of hormones into the blood/lymph (ductless glands)

B. alter existing cell activities (enhance or diminish) through the actions of the chemical hormones on
the cells

C. closely integrated with nervous system in regulating body activities (maintain homeostasis), often
referred to as the NEUROENDOCRINE SYSTEM.

1. endocrine system is long lasting but slow to get going hormones enter blood -> organs ->
removed by kidneys wide spread effects

2. nervous system is short lasting but fast starting electrical signals sent down axons to organs
localized effects

3. HYPOTHALAMUS is the link between the nervous and endocrine systems and is referred to
as a NEUROENDOCRINE ORGAN
HORMONES
A. chemicals (mostly proteins and some steroids) secreted by cells into extracellular fluids (including
blood) that regulate existing cell functions

B. SPECIFICITY OF HORMONES

1. TARGET CELLS: cells affected by the particular hormone

2. RECEPTORS for specific hormones are found only on target cells
CONTROL OF HORMONE RELEASE
A. primarily through negative feedback loops: increased hormone concentration inhibit hormone release

B. three main control mechanisms for hormone release other than negative feedback; stimulation of
hormone release may be from more than one control mechanism

1. HUMORAL STIMULUS (simplest)
a. secretion is in response to changing blood concentrations of ions and nutrients
b. lo [Ca+] -> PTH release

2. NEURAL STIMULUS (rare)
a. nerve fibers stimulate hormone release
b. stress -> symp N.S. -> adrenal medulla -> norepinephrine

3. HORMONAL STIMULUS (by tropic hormones) hormones stimulate the release

C. NERVOUS SYSTEM can override normal endocrine controls to maintain homeostasis
HYPOTHALAMUS
1. secretes tropic hormones regulating release of hormones from the anterior pituitary (homeostatic control)
prolactin inhibitory hormone (PIH) thyrotropic releasing hormone (TRH)
prolactin releasing hormone (PRH) growth hormone releasing hormone (GHRH)
gonadotropic releasing hormone (GnRH) growth hormone inhibiting hormone (somatostatin) (GHIH)
corticotropic releasing hormone (CRH)

2. secretes hormones to be stored in the posterior pituitary for later release by the posterior pituitary
Antidiuretic hormone (ADH)
Oxytocin (OT)
PITUITARY GLAND (HYPOPHYSIS)
LOCATION: in sella turcica of sphenoid bone
SHAPE: pea-sized, round, bilobed (anterior and posterior) attached to HYPOTHALAMUS by
INFUNDIBULUM
ANTERIOR LOBE: ADENOHYPOPHYSIS
a. hormone production/secretion CONTROLLED by secretion of horm. from hypothalamus
b. two classes of hormones from adenohypophysis
i. TROPINS: regulate other endocrine glands TSH, ACTH, FSH, LH
ii. NON-TROPIC HORMONES: GH, PRL MSH
c. ANTERIOR PITUITARY HORMONES AND HYPOTHALAMIC REGULATORS
** indicates a hormone produced in hypothalamus
GROWTH HORMONE - GH
TARGET: most tissue cells
FUNCTION: stimulate protein synthesis/growth, mobilize fat for energy, conserves
glucose (^blood glucose)
REGULATION:
**GHRH: growth hormone releasing hormone
**GHIH (SOMATOSTATIN):growth hormone inhibiting hormone
-FEEDBACK conc. of GH in blood
THYROID STIMULATING HORMONE - TSH
TARGET: thyroid gland
FUNCTION: stimulates normal thyroid growth, stimulates thyroid hormone secretion
REGULATION:
**TRH - thyrotropin releasing hormone
**GHIH
- FEEDBACK conc. of TSH, TH in the blood
ADRENOCORTICOTROPIC HORMONE - ACTH
TARGET: adrenal cortex of adrenal gland
FUNCTION: stimulate corticosteroid hormone secretion to combat the effects of stress
REGULATION:
**CRH: corticotropin releasing hormone
- feedback conc. of ACTH and corticosteriods in blood
MELANOCYTE STIMULATING HORMONE: MSH
TARGET: melanocytes in skin
FUNCTION: stimulate production of melanin
REGULATION: hypothalamic neuronal stimulus of adenohypophysis
PROLACTIN: PRL
TARGET: mammary glands
FUNCTION: stimulate milk production
REGULATION:
**PRH: prolactin releasing hormone
**PIH: prolactin inhibiting hormone
ESTROGEN: low estrogen, stimulates PIH and inhibits PRL
hi estrogen, stimulates PRH and stimulates PRL
SUCKLING: increases PRL
GONADOTROPINS
LH & FSH
LUTEINIZING HORMONE: LH
TARGET: gonads
FUNCTION: stimulate secretion of gonadal hormones
females: induce ovulation, stimulate estrogen/progesterone secretion,
assists in egg maturation
males: testosterone production
FOLLICLE STIMULATING HORMONE: FSH
TARGET: gonads
FUNCTION: stimulate egg and sperm production and estrogen production
REGULATION OF BOTH FSH AND LH
**GnRH: gonadotropin releasing hormone
- feedback: conc. of testosterone, estrogen, progesterone in blood
NO RECEPTORS FOR HORMONES ON TARGET CELLS UNTIL PUBERTY
POSTERIOR LOBE OF PITUITARY: NEUROHYPOPHYSIS
a. stores hormones produced by hypothalamus OT, ADH
b. CONTROLLED by nervous stimulation by hypothalamus
c. POSTERIOR PITUITARY AND THE HYPOTHALAMIC HORMONES STORED THERE
OXYTOCIN: OT
TARGET: smooth m.: especially in uterus and in breast ducts
FUNCTION: stimulates contraction of uterus during labor, allows "milk let-down" for
nursing, promotes sexual arousal and "bonding" behaviors in males/females
REGULATION:
+ FEEDBACK: stretch of uterus/cervix toward the end of child birth ^ OT release
causing more uterine contractions ALSO in response to stretching of the
breasts due to milk production (a function of PRL), OT is stimulated, or when
suckling occurs, milk is let down.
ANTIDIURETIC HORMONE: ADH (diuresis = urine production)
TARGET: kidneys, blood vessels
FUNCTION: regulate water and electrolyte balance by causing vasoconstriction (causing
less urine to be produced) when BP drops or when dehydration occurs
REGULATION: fluid balance/volume is monitored by OSMORECEPTORS if the
blood concentration increases or if fluid volume falls, these receptors
are stimulated and tell the hypothalamus to produce more ADH and
tell the posterior pituitary to release the ADH. Less urine is made, fluid
volumes stabilize and less ADH is released.
HYPOSECRETION:
DIABETES INSIPIDUS: large urine output POLYUREA
large thirst POLYDIPSIA
THYROID GLAND
LOCATION: anterior side of trachea below larynx
SHAPE: BUTTERFLY: rt. and lt. lobes and ISTHMUS
FUNCTION: production and secretion of
a. THYROID HORMONE: TH
b. CALCITONIN: CT
THYROID HORMONE (metabolic hormone) THYROXINE
TARGET: most cells in the body
FUNCTION: metabolic hormone
stimulates use of O2 in breakdown of fats/sugars, stimulates protein
production, increases body temperature
REGULATION:
TRH: from hypothalamus
TSH: from anterior pituitary
-FEEDBACK: ^ TH in blood, inhibit TSH.....
NEED FOR ENERGY: increased production during pregnancy, cold climate
(HYPOTHALAMUS WILL OVERRIDE THE NEGATIVE FEEDBACK)
GHIH: from hypothalamus inhibits TSH .....
ABUNDANCE OF IODINE: needed to make the hormone TH
CALCITONIN: CT
TARGET: bones, osteoblasts
FUNCTION: decrease blood calcium by stimulating bone formation
REGULATION:
hi Ca in blood stimulates CT
lo Ca in blood inhibits CT release
PARATHYROID GLANDS
LOCATION: embedded in the posterior aspect of the thyroid gland
SHAPE: small clusters of cells usually 4 to 8 clumps
FUNCTION: produce and secrete PTH

PARATHYROID HORMONE: PTH
TARGET: bones (osteoclasts), kidneys
FUNCTION: increase blood Ca levels by breaking down bone, causing Ca retention from
urine, and activation of VIT D for Ca uptake from the intestine
REGULATION:
lo calcium in blood stimulates PTH
hi calcium in blood inhibits PTH
ADRENAL (SUPRARENAL) GLANDS
LOCATION: above kidneys
SHAPE: pyramidal, outer region = CORTEX, inner region = MEDULLA
FUNCTION: maintain homeostasis by combating the effects of stress
ADRENAL CORTEX HORMONES: steroid horm LONG TERM STRESS CONTROL
MINERALOCORTICOIDS: ALDOSTERONE
GLUCOCORTICOIDS: CORTISOL
GONADOCORTICOIDS: ANDROGENS (TESTOSTERONE) and ESTROGENS
MINERALOCORTICOIDS: ALDOSTERONE
TARGET: kidneys causing reabsorption of Na+ from urine K+ excretion
FUNCTION: regulate electrolyte (Na, K) balance in body fluids by causing uptake
of electrolytes from urine (water will follow)
REGULATION:
RENIN-ANGIOTENSIN SYSTEM
*kidney cells stimulated when blood volume drops or when solute conc.
in blood drops.
*kidney cells release RENIN into blood
*renin changes ANGIOTENSINOGEN -> ANGIOTENSIN II
through a series of events
*angiotensin II stimulates aldosterone release

Lo Na and Hi K ION concentrations stimulate aldosterone release

ACTH from the ant. pit. during stress ^ aldosterone release to ^BP to meet
body needs during stress

ATRIAL NATRIURETIC FACTOR hormone from the heart
when BP is high. Inhibits renin/aldosterone
GLUCOCORTICOIDS: CORTISOL
TARGET: most body cells
FUNCTION: help to resist the effects of stress by increasing blood sugar: use fats
for energy and gluconeogenesis
REGULATION:
CRH, ACTH increase release
-FEEDBACK
GONADOCORTICOIDS: ANDROGENS (TESTOSTERONE) and ESTROGENS
TARGET: most body cells
FUNCTION: puberty onset
REGULATION: ACTH
ADRENAL MEDULLA: EPINEPHRINE, NOREPINEPHRINE brief stress regulator
TARGET: cardiac muscle cells, smooth muscle lining bv's
FUNCTION: "fight or flight response", increase heart rate, constrict blood vessels to ^BP
REGULATION: stress increases the release of these hormones, SYNS stimulates release
PINEAL GLAND (EPIPHYSIS)
LOCATION: in brain, near third ventricle and posterior commissure
SHAPE: pea sized gland
FUNCTION: produce, release MELATONIN
MELATONIN
TARGET: most cells of body
FUNCTION: puberty onset, regulate body cycles and patterns (sleep, eat, temp...)
REGULATION: by natural light (inhibits melatonin) and dark
THYMUS GLAND
LOCATION: below sternum, above heart
SHAPE: 2 lobes, big during childhood, atrophies with age
FUNCTION: production of thymosin

THYMOSIN
TARGET: white blood cells, LYMPHOCYTES
FUNCTION: matures WBC’s into T-lymphocytes, cells of the immune system
Regulated by immunity needs, age
PANCREAS
LOCATION: inf. and post. to stomach, between duodenum and Spleen
SHAPE: long, narrow
FUNCTION: production of insulin, glucagon (ISLETS OF LANGERHANS)
GLUCAGON: (from alpha cells)
TARGET: liver
FUNCT: inc. blood sugar & dec. blood amino acids by glycogenolysis, gluconeogenesis
REGULATION:
hi amino acids or low blood sugar stimulate glucagon
hi glucose, somatostatin inhibit glucagon
INSULIN: (from beta cells)
TARGET: muscle cells and other tissue cells
FUNCTION: decrease blood sugar by glucose uptake into cells
increase cellular use of glucose
increase glycogenesis, lipogenesis
increase protein synthesis
REGULATION:
hi AA, hi fatty acids, hi glucose stimulate insulin
lo glucose, somatostatin inhibit insulin

HYPOSECRETION
DIABETES MELLITUS: hi blood sugar, hi sugar in urine,
increased urine production
polyurea, polydipsia, polyphagia (eat more)
increased protein degradation, increased fat breakdown --> buildup
of KETOACIDS in blood (decreased pH)

type I (IDDM): no insulin production, hard to control, juvenile onset

type II (NIDDM): lo insulin production or receptors unable to respond to insulin.
highly genetic, weight related, age onset
GONADS: TESTICLES AND OVARIES
cover in reproductive chapter
CHAPTER 16 THE ENDOCRINE SYSTEM
CHAPTER 16 THE ENDOCRINE SYSTEM