THE ENDOCRINE SYSTEM
CHAPTER 16
_______________: study of hormones and endocrine organs
Exocrine glands:
 Produce_______________substances (ex. sweat, saliva)
 Have _______________ to carry secretion to membrane surface
Endocrine glands:
 Produce _______________ (ex. aldosterone, oxytocin)
 Do not have _______________, secretions are released directly into the
bloodstream
Endocrine glands: _______________, _______________, _______________,
_______________, and ______________________________
Neuroendocrine gland: _______________
Organs and tissues that have exocrine and endocrine functions: _______________,
_______________, _______________
Tissues and organs that produce hormones: ______________________________,
_______________, and cells in walls of the ______________________________,
_______________, _______________, and _______________
_______________: long-distance chemical signals that travel in blood or lymph
Two main classes of hormones:
 _____________________________________________
 _______________ (synthesized from cholesterol)
______________________________: tissues with receptors for specific hormone or
hormones
Hormones alter target cell activity by:
 Alter plasma membrane _______________
 Stimulate synthesis of _______________
 Activate or deactivate _______________
 Induce ______________________________
 Stimulate _______________
Water-soluble hormones:
 Include all _____________________________________________hormones
except thyroid hormone
 Act on _____________________________________________ (cannot enter the
cell)
 Act via G protein ______________________________
Plasma Membrane Receptors and Second Messenger Systems: cAMP
1. _______________ (first messenger) binds to
_____________________________________________located on the
outside the cell
2. Receptor activates _______________located inside the cell
3. G protein activates ______________________________
4. Adenylate cyclase converts ATP to _______________ (second messenger)
5. cAMP activates ______________________________that phosphorylate proteins
 Phosphorylating proteins can either activate or inactivate them
 cAMP keeps working until it is degraded by the enzyme _______________
 Intracellular enzymatic cascades have huge ______________________________
Lipid-soluble hormones:
 Include all ______________________________and thyroid hormone
 Act on ______________________________ (can enter the cell)
 Directly activate _______________
Intracellular Receptors and Direct Gene Activation
1. _______________ diffuses into target cells and bind with
______________________________
2. Receptor-hormone complex enters _______________
3. Receptor-hormone complex binds to specific region of _______________
4. Binding prompts DNA transcription to produce _______________
5. mRNA directs ______________________________
Target cell activation depends on three factors:
 ______________________________of hormone
 ______________________________on or in the target cell
 ______________________________between receptor and hormone
______________________________: target cells form more receptors in response to low
hormone levels
______________________________: target cells lose receptors in response to high
hormone levels
Blood levels of many hormones are controlled by _______________ _______________
_______________ (result of a process regulates the process itself)
Endocrine gland are stimulated to synthesize and release hormones in response to:
 ______________________________: changing blood levels of ions and nutrients
directly stimulate secretion of hormones
o Example: low Ca2= concentration in blood stimulates the release of
parathyroid hormone which increases Ca2+ levels
 ______________________________: nerve fibers stimulate hormone release
o Example: excitation of sympathetic fibers in the adrenal medulla
stimulates the release of epinephrine and norepinephrine
 ______________________________: hormones stimulate other endocrine organs
to release their hormones
o Tropic hormones: hormones that stimulate the release of other hormones
o Example: hormones from the hypothalamus stimulate the release of
hormones from the pituitary gland
______________________________modifies stimulation of endocrine glands and their
negative feedback mechanisms (nervous system can override normal endocrine controls)
Interaction of Hormones at Target Cells:
 _______________: one hormone cannot exert its effects without another hormone
being present
o Example: estrogen and progesterone work together in uterine development
 _______________: more than one hormone produces same effects on target cell;
their combined effects are amplified
o Example: glucagon and epinephrine each increase blood glucose levels,
together their effects increase 150%
 _______________: one or more hormones oppose(s) action of another hormone
o Example: insulin lowers blood glucose levels while glucagon raises blood
glucose levels
Pituitary gland has two major lobes:
 Posterior pituitary composed of ______________________________
 Anterior pituitary composed of ______________________________
Pituitary-hypothalamic Relationships:
 Posterior pituitary is a down growth of hypothalamic neural tissue
 Neural connection to the hypothalamus is the
_____________________________________________
o Nuclei originating in the hypothalamus synthesize _______________
which are transported down the hypothalamic-hypophyseal tract and
stored in posterior pituitary
Pituitary-hypothalamic Relationships
 Anterior pituitary originates as out pocketing of oral mucosa
 Vascular connection to the hypothalamus is the
_____________________________________________
o _____________________________________________from the
hypothalamus travel via the hypophyseal portal system to the anterior
pituitary regulating hormone secretion there
Posterior Pituitary and Hypothalamic Hormone: _______________
 Strong stimulant of ______________________________that is released during
childbirth
 Hormonal trigger for ______________________________
Posterior Pituitary and Hypothalamic Hormone:
____________________________________________________________
 Inhibits ______________________________thereby regulating water balance
 Targets ______________________________for water reabsorption
 Inhibited by _______________ and _______________
 High concentrations causes _______________ resulting in increased blood
pressure (vasopressin)
Decreased ADH secretion: ______________________________
 Increased thirst
 Increased urine output
 Regular blood glucose levels
Anterior Pituitary Hormone: ______________________________
 ______________________________on metabolism: GO
o _______________ metabolized and used for fuel
o _______________ metabolized increasing blood glucose
o Increased _______________ breakdown and _______________ release to
blood
 ______________________________on growth: GROW
o Stimulates the liver and other tissues to produce growth-promoting
proteins,
_____________________________________________
_______________ (IGFs)
o IGFs increase _______________ formation and _______________ growth
o IGFs increase _______________ synthesis and _______________ growth
and proliferation
Increased GH:
 In children _______________
 In adults acromegaly (overgrowth on bones)
Decreased GH:
 In children _______________In adults no effect
.
Anterior Pituitary Hormone:
____________________________________________________________
 Stimulates normal development and secretory activity of _______________
 Release triggered by _____________________________________________from
hypothalamus
 Inhibited by rising blood levels of ______________________________that act on
pituitary and hypothalamus
Anterior Pituitary Hormone: _____________________________________________
 Stimulates adrenal cortex to release _______________
 Triggered by hypothalamic
____________________________________________________________
Anterior Pituitary Hormone: _______________
 ____________________________________________________________stimula
tes gamete (egg or sperm) production
 _____________________________________________promotes production of
gonadal hormones
 Release triggered by
____________________________________________________________during
and after puberty
Anterior Pituitary Hormone: ______________________________
 Stimulates ______________________________
 Regulation of PRL release primarily controlled by
____________________________________________________________
 PRL blood levels rise toward end of pregnancy
 Suckling stimulates PRL release
Thyroid Gland Structure:
 Two lateral lobes connected by median mass called _______________
 Composed of ______________________________that produce glycoprotein
thyroglobulin
 _______________ (fluid composed of thyroglobulin and iodine) fills lumen of
_______________and is precursor of thyroid hormone
 ______________________________produce the hormone calcitonin
Thyroid Gland: ______________________________
 _______________ metabolic rate and heat production
 _______________ of tissue growth and development
 _______________ blood pressure
 Two related compounds
o ______________________________has 2 tyrosine molecules + 4 bound
iodine atoms
o ______________________________has 2 tyrosines + 3 bound iodine
atoms
 Rising TH levels provide negative feedback inhibition on release of
_______________
Synthesis of Thyroid Hormone
1. _______________ synthesized and discharged into
______________________________
2. _______________actively taken into cell and released into lumen
3. Iodide oxidized to _______________
4. Iodine attaches to _______________
5. Iodinated tyrosines link to form _______________ and _______________
6. Colloid is _______________ and vesicle is combined with a lysosome
7. T3 and T4 are cleaved and diffuse into _______________
Increased TH secretion: ______________________________
 Autoimmune disease against follicular cells
 Increased metabolic rate
Decreased Iodine: _______________
 Low dietary iodine levels result in thyroglobulin becoming trapped in follicles
 Engorged follicles cause enlargement of the thyroid gland
Thyroid Gland: _______________
 Produced by parafollicular cells
 At higher than normal doses it inhibits osteoclast activity and stimulates Ca2+
uptake and incorporation into bone matrix,
____________________________________________________________
Parathyroid Glands
 Four to eight tiny glands embedded in posterior of the _______________
 Contain _______________ _______________ (function unknown) and
______________________________that secrete parathyroid hormone (PTH)
Parathyroid Gland: ______________________________
 Most important hormone in ______________________________
 Stimulates osteoclasts to digest bone matrix and release Ca2+ to blood
 Enhances ______________________________
 Promotes _____________________________________________ (by kidneys);
increases absorption of Ca2+ by intestinal mucosa
Increased PTH levels: weakened bones
Decreased PTH levels:
 More excitable neurons
 Tetany, convulsions
Adrenal Glands: Structure
 Paired, pyramid-shaped organs atop _______________
 ______________________________: nervous tissue; part of sympathetic nervous
system
 ______________________________: three layers of glandular tissue that
synthesize and secrete corticosteroids
o ______________________________: mineralocorticoids
o ______________________________: glucocorticoids
o ______________________________: gonadocorticoids
Adrenal Cortex, Zona Glomerulosa: Mineralocorticoids
 _______________ most potent mineralocorticoid
 Stimulates ______________________________and
______________________________by kidneys and the elimination of K+
o Increased water retention increases blood volume resulting in increased
blood pressure
 Release triggered by _____________________________________________and
______________________________and rising blood levels of K+
____________________________________________________________: decreased
blood pressure stimulates kidneys to release renin which triggers formation of
angiotensin II, a potent stimulator of aldosterone release (increased blood pressure)
Adrenal Cortex, Zona Fasiculata: Glucocorticoids
 _______________ only glucocorticoid in humans
 Released in response to _______________,
____________________________________________________________, and
_______________
 Keeps _____________________________________________relatively constant
by gluconeogenesis (formation of glucose from fats and proteins)
 Maintain ______________________________by increasing action of
vasoconstrictors (raises blood pressure)
Increased ACTH produce increased Coritsol release:
______________________________
 Depression of cartilage and bone formation
 Increase inflammation
 Depressed immune system
Adrenal Cortex, Zona Reticularis: Gonadocorticoids (Sex Hormones)
 Most _______________ _______________ (male sex hormones) converted to
testosterone in tissue cells, some to estrogens
 May contribute to onset of puberty and appearance of secondary sex
characteristics
Adrenal Medulla
 _______________ synthesized by the medullary chromaffin cells
 Causes _______________,
_____________________________________________, and
____________________________________________________________
 _______________ stimulates metabolic activities, bronchial dilation, and blood
flow to skeletal muscles and heart (80% of catecholamine produced)
 _______________ influences blood pressure (20% of catecholamine produced)
Pineal Gland
 Small gland hanging from roof of third ventricle
 _______________ secrete _______________which effects day/night cycles
 ______________________________: dense particles containing Calcium salts
Pancreas: Structure
 Triangular gland partially behind stomach
 ______________________________ (exocrine) produce enzyme-rich juice for
digestion
 ______________________________ (islets of Langerhans) contain endocrine
cells
o ______________________________produce glucagon (hyperglycemic
hormone)
o ______________________________produce insulin (hypoglycemic
hormone)
Pancreas: Alpha (α) cells, Glucagon
 Causes ___________________________________________________________
 _______________: breakdown of glycogen to glucose in the live
 _______________: synthesis of glucose from lactic acid and non-carbohydrates
Pancreas: Beta (β) cells, Insulin
 Causes _____________________________________________levels by
enhancing membrane transport of glucose into fat and muscle cells
 Inhibits glycogenolysis and gluconeogenesis
Factors That Influence Insulin Release
• ____________________________________________________________is the
primary stimulus
• Rising blood levels of ______________________________and
______________________________
• Release of _______________ by parasympathetic nerve fibers
• Hormones glucagon, epinephrine, growth hormone, thyroxine, glucocorticoids
Diabetes mellitus (DM)
• Due to _______________ (type 1) or _______________ (type 2) of insulin
• _______________: glucose spilled into urine
• _______________: fats used for cellular fuel
o Excessive ketones from lipidemia can results in ketoacidosis
Three Cardinal signs of Diabetes Mellitus
• _______________: huge urine output
• _______________: excessive thirst
• _______________: excessive hunger and food consumption
Gonads produce steroid sex hormones
• _______________ produce estrogens and progesterone
o Estrogen responsible for maturation of reproductive organs and secondary
sexual characteristics
o Progesterone responsible for breast development and cyclic changes in
uterine mucosa
• _______________ secretes estrogens, progesterone, and human chorionic
gonadotropin (hCG)
• _______________ produce testosterone
o Testosterone responsible for maturation of male reproductive organs and
secondary sexual characteristics
Adipose Tissue
• _______________: appetite control; stimulates increased energy expenditure
• _______________: insulin antagonist
• _______________: enhances sensitivity to insulin
Enteroendocrine Cells of Gastrointestinal Tract
• _______________: stimulates release of HCl
• _______________: stimulates liver and pancreas
• _______________: stimulates pancreas, gallbladder, and hepatopancreatic
sphincter
• _______________: stimulates stomach contractions
Heart
• _____________________________________________:decreases blood Na+
concentration, therefore blood volume and blood pressure
Kidneys
• _______________: signals production of red blood cells
• _______________: initiates the renin-angiotensin-aldosterone mechanism
Skin
•
_______________: precursor of vitamin D
Thymus
• Large in infants and children; shrinks with age
• Produces _______________,_______________, and _______________
• Involved in normal development and maturation of
______________________________