Download Unit 9 Endocrine system notes

• The two regulatory systems involved in
maintenance of homeostasis are the nervous
system and the endocrine system
• Remember: homeostasis: the condition in
which the body’s internal environment remains
relatively constant
• Neural control is quick, brief and generally
results muscle contractions or glandular
secretions
Endocrine Hormones
• Is made up of ductless glands that secrete
directly into the blood.
• Affects cell activities by releasing chemical
messengers ( hormones) directly into the
bloodstream, the target cells are varied (may be
all over body)
• Hormones control generally takes from minutes
to hours to occur and the changes are long
lasting, usually due to changes in the metabolic
activity of the target cell
Endocrine glands
• Remember: exocrine glands: secrete
products by way of ducts onto a surface.
Ex sweat glands, digestive glands, oil
glands
• Endocrine glands: secrete produces into
extracellular spaces where they are picked
up and transported by the circulatory
system
Hormones
• A secretion of endocrine tissue that is
transported in the blood and its signaling
influences a wide variety of body functions
ranging from bone growth and muscle
grow to the concentration of glucose in the
blood.
2 major types of hormones
• 1. Amino acid based :
• molecules: range from small amino acids to
huge proteins
• Are water soluble
• Include majority of hormones
• 2. Steroids: ( derivatives of cholesterol)
• Are lipid soluble so can cross cell membranes
• Includes only gonads and some adrenal
hormones
Mechanisms of hormone action:
• Since hormones are released into the
circulatory system, virtually all tissues are
exposed to them.
• The ability of a cell to respond to a
hormone depends on the presences of
large protein molecules called receptors
which are very specific ( lock and key
analogy)
Mechanisms of hormone action:
• They bind with specific hormones and not
others.
• The combination of a hormone and receptor
activates a chain of events resulting in the
hormonal effect
• A single type of hormone can have different
effects on different cells because they might be
either different types of receptors, or varying
quantities of receptors producing varying
magnitudes of effects
2 major types of receptors are:
• 1. Plasma membrane receptors: found
on cell membrane
• 2. Intracellular receptors: found within
cell.
• React with hormones that enter cell
membrane and generally initiate or stop
protein synthesis
In General, A hormones effect is
one of the following:
1.
2.
3.
4.
Change in membrane permeability
Start or stop protein synthesis
Activate or deactivate enzymes
Induce or stop secretory activites
The endocrine glands
• Are pockets of hormones producing tissue
found in the : stomach, heart, small
intestines and placenta
• Additionally there are “local hormones”
called prostaglandins
Prostaglandins
• are membrane associated lipids produced
by possibly all cells.
• Some characteristics:
• 1. have a hormone-like effect but are not
true hormones
• 2. have local effect only if not produced by
endocrine glands. Ex of their functions is
influencing blood clotting to effect
inflammation
Pituitary gland (hypophysis)
• Located in the sella turcica of sphenoid bone
and is attached to the hypothalamus of the brain
by the stalk-like infundibulum
• Regulates so many bodily activities ( especially
glands) that it is called the master gland of the
body
• The pituitary gland is stimulated/inhibited by
factors produced in the hypothalamus of the
brain
Pituitary gland
• Is divided into:
• Anterior pituitary gland: adenohypophysis
which makes up 75% of mass of the pituitary
gland and releases 7 different hormones
• Posterior pituitary gland: Neurohyphysis
which is not really a gland, it stores and secretes
hormones which are produced in the
hypothalamus
•
Hypophysis
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Know 2
division:

Adenohypophy
sis ( anterior ½)
H/F
Neurohpophysis

(posterior ½) H/F
it has fibers and
is lighter
The anterior pituitary synthesizes and secretes the
following important endocrine hormones:
1.
FSH ( follicle stimulating hormone):
regulates hormonal activities of gonads such
as sperm or egg production, (ovulation),
estrogen and progesterone release and
testosterone
2. Luteinizing hormone (LH): same as above
3. ACTH (adrenocorticotropic hormone)
regulates endocrine activity of adrenal gland
(cortex)
The anterior pituitary synthesizes and secretes the
following important endocrine hormones:
4. TSH (thyoid stimulating hormone)
(thyrotropic hormone): functions ingrowth
and activity of thyroid gland
5. Growth hormone (SRH) (somatotropin):
functions in metabolism/body size, stimulates
growth via protein synthesis, deficiency causes
dwarfism
6. LTH (leuteotropic hormone) (prolactin):
lactation of mammary glands
The anterior pituitary synthesizes and secretes the
following important endocrine hormones:
7. MSH ( meloancyte stimulating
hormone) not significant in humans,
may be a precursor to several other
hormones
Hormones of posterior pituitary
gland
1. oxytocin: functions in uterine contraction
and mammalary gland due to smooth
muscle contractions
2. ADH (antidiuretic hormone)
(vasopresin) functions in increasing
blood volume and pressure, also
constricts blood vessels and affects the
kidney tubules causing them to reabsorb
water
Thyroid gland
• Located below the larynx and is composed
of spherical bags called follicles
• The follicle walls are simple cuboidal
epithelium and are called follicular cells
• The follicular cells produce and store the
thyroid hormones in the follicles as
thyroblobin in a gelatin state called a
colloid
Thyroid gland
• Cells outside of the follicle walls are called
parafollicular cells
Thyroid Gland
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Know
Thyroid
follicle
Thyroid
colloid
Follicular
cells H/F
Parafollicular
cells H/F
Thyroid hormones
1. Thyroxin: produced by follicular cells
and affects body metabolism
2. Calcitonin: produced by parafollicular
cells and decreases calcium levels. It is
antagonistic against parathyroids attempt
to increase calcium
Thyroid disorders: hyperthyroidism:
 Characteristics:
 Abnormal
metabolic rate
 Sensitive to heat
 Restless, overactive
 Appears mentally alert
 Eyes protrude (exophthalms)
 Irritable de to sensitive nervous system
 Enlarged thyroid ( goiter)
Thyroid disorders: hypothyroidism
 Characteristics:
 Low
metabolic rate
 Abnormal sensitivity to cold
 Physical sluggishness
 Poor appetite
 Appears mentally dull
 Swelling of body tissue
 Tendency to gain weight
Parathyroid gland
• Tiny glands located on posteror surface of
the thyroid gland
• Hormone secreted is:
• Parathrormine: which increases calcium
levels by increasing absorption in the
kidneys and intestines. If this hormone
functions improperly the result is weak
brittle bones
Disorder of parathyroid gland
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•
•
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Hypoparathyroidism: Characteristics
Blood calcium drops
Nervous system excitable
Muscles undergo tetanic contractions
(cramps and seizures)
• Can die due to respiratory failure
• Treatment large does of vitamin D and
calcium
Disorder of parathyroid gland
•
•
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Hyperparathyroidism: Characteristics
Blood calcium is high
Nervous system depressed
Muscle contractions weak and sluggish
Usually caused by tumors
Bones deformed and soft due to
osteoclast
Parathyroid Gland

Just Identify it and know
H/F
Thymus gland
• Located below the thyroid gland,
superficial to the heart
• Is a large gland in infants which diminishes
in size with age
• Hormone produced:
• Thymosin: for production and
programming of T cells (immunity) is gone
by age 35
Pineal gland
• Found in center of brain,
• Its function is mostly a mystery
• Hormone produced:
• Melatonin: may be involved in circadian
rhythems
Pancreas
• Located behind and inferior to the stomach
• Has both endocrine and exocrine functions
( called a mixed gland)
• Endocrine portion consists of clusters of
cells called islets of Langerhan which
consist of 2 types of cells:
• 1: alpha cells: in middle
• 2. beta cells: outer edge
Pancreas
• Exocrine section is the acini cells which
secrete various enzymes for digestive
purposes
PANCREAS
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Know
 Acini cells
 Islet of
Langerhans
 Alpha cells (
found at edges
H/F)

Beta cells (
found in center
H/F)
Diabetes
• Any of a various disorders having in common the
abnormal amounts of urine produced
• Diabetic insipidus: pituitary disorder resulting in
insufficient ADH and excess fluid loss
• Diabetic mellitus: collection of diseases
grouped together because they result in
excessive sugar levels in blood
(hyperglycemia)
• Hypoglycemia: low blood sugar
Diabetic mellitus
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2 types:
Type I: juvenile onset, lack insulin activity
insulin dependent
 Something destroys insulin producing capacity
of beta cells
 Type II: 90%, maturity onset ( after age 40),
alpha cells
 Strong genetic link??? Unable to use insulin
produced by body due to abnormal receptors in
cell membrane
Hormones released by Pancreas
1.
2.
•
Insulin: released by beta cells
functions to decrease glucose
Glucose: released by alpha cells
which secrete glucagon that
increases sugar levels
Hyperinsulinism: rare, usually tumor
of islet cells
Adrenal Gland
 Located
on the superior surface of each
kidney,
 composed of 2 distinct layers: adrenal
cortex and adrenal medulla
 Adrenal medulla is the central portion of
the gland
 Adrenal cortex is the outer layer of the
gland and has 3 zones
Adrenal Gland
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1.
2.
3.
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Know:
Adrenal cortex and its sublayers:
Zona glomerulosa (loops and circles _ H/F)
Zona fasiculata (widest H/F)
Zona reticularis ( netlike with brown spots H/F)
Adrenal medulla H/F
Capsule
Adrenal hormones
 Adrenal
Medulla: central portion
 Hormones:
 Epinephrine: fight or flight , increase
respiratory and metabolic rates and
constrict blood vessels
 Norepinephrine: same
Adrenal hormones
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Adrenal cortex: outer layer has 3 zones
 1. Zona glomerulosa (outer layer): hormone is
aldosterone (mineralocorticoid) which regulates
sodium ion reabsorption by kidneys
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2. Zona fasiculata (middle)
 Hormone is cortisone (glucocorticoid) functions
in increasing blood glucose levels
Adrenal hormones
 3.
zona reticularis: (inner layer)
 Hormone is sex hormones
(gonadocorticoids)
Adrenal Gland
Adrenal disorders: hyposecretions
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Causes Addison’s disease
Characteristics:
Low sodium, high potassium
Low blood glucose
Dehydration
Low blood pressure
Increased skin pigmentation (ACTH mimics MSH)
Mental lethargy
Muscular weakness
Weight loss
Death in a few days if untreated
Adrenal disorders: hypersecretions
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Causes Cushing’s Disease
Characteristics
Decrease in protein
wasting of muscle and loss of bone tissue
Blood glucose elevated
Puffy skin due to water retention
Sodium high
Fat deposits between shoulders and in face making
buffalo hump and moon face
Spindly arms and legs
Poor wound healing
Gonads
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Ovaries: primary source of female sex
hormones
 Hormones
 Estrogen: secondary sex characteristics
 Progesterone: menstrual cycle
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Testes: primary source of male sex hormones
 Hormones:
 Testosterone: secondary sex characteristics of
male
 MORE LATER