Download ENDOCRINE SYSTEM

ENDOCRINE SYSTEM
Endocrine glands secrete chemical messages into the
blood stream that affects distant specific target
tissues
Endocrine Glands are small in size (less than 1/10th and
kg total) but big in maintaining homeostasis.
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HORMONES- chemical messengers released into the
blood stream that direct activities in the body’s cells
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FUNCTIONS
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Reproduction
Growth and development
Body defense system
Maintain electrolyte, water, and nutrient balance
Regulate cellular metabolism
3 CLASSES OF HORMONES
1. Amino acid based- proteins, peptides, and
amines
2. Steroids- built around a core of cholesterol
(hydrophobic – does not dissolve in water)-sex
hormones and adrenal hormones
3. Prostaglandins – fatty acid based- act locally at
site of release
How do hormones work?
TARGET CELLS or TARGET ORGANS- hormones
must attach to specific protein receptors (on the
plasma membrane)
When hormone binds it typically changes the cell
in one of the following ways1. Changes plasma membrane permeability or electrical
state
2. Synthesis of proteins or enzymes in the cell
3. Activate or deactivate enzymes in the cell
4. Stimulation of mitosis (cell division)
STEROIDS- hydrophobic- so
therefore fat soluble
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Page 281
STEP 1
diffuses
through plasma
membrane
STEP 2
enters the
nucleus
STEP 3
binds to
specific receptor proteins
in nucleus
STEP 4
binds to
specific sites of DNA
STEP 5
activates
genes
STEP 6
genes make
new proteins
NONSTEROIDAL HORMONES- not
fat soluble
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Page 281STEP 1 binds to receptor
on plasma memb
STEP 2
sets off a
series of reactions that
activate enzyme
STEP 3- produces a
second messenger
molecule
STEP 4- produces cells
predicted reaction to the
hormone
Types of endocrine glands

HORMONAL- glands prodded into action
due to hormones

NEURAL- glands prodded into action due
to neural stimulation

HUMORAL- changing blood levels of
certain ions (Ca+) for example prods the
glands into action
NEGATIVE FEEDBACK SYSTEM
•Negative feedback limits amount of hormone that is
released
Hypothalamus
Set point
Levels
OK ?
Blood
•Yes?
•No?
Hypothalamus releases a
"Releasing
Hormone"
Pituitary gland releases
"Tropic
hormone"
Peripheral gland releases its hormone
Structure and function of Endocrine
glands
PITUITARY GLAND (HYPOPHYSIS)- “Master
endocrine gland”- located in the sella turcica of
the skull consists of 2 functional areas
ANTERIOR PITUITARY- secretes the 4 tropic
hormones- activates other endocrine glands
POSTERIOR PITUITARY- serves as a storage area
for two hormones to be used when activated by
the neurons of the hypothalamus
ANTERIOR PITUITARY
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1.
Secretes 4 tropic hormones
Receives hormones from hypothalamus called
“regulating factors”
Growth hormone (GH)
TROPIC HORMONES
1. Thyroid stimulating hormone (TSH)
2. Adrenocorticotropic hormone (ACTH)
3. Gonadotropins
1.
2.
Follicle stimulating hormone (FSH)
Luteinizing hormone (LH)
GROWTH HORMONE
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(increases amino acid transport into cells and
increases protein synthesis, mitosis, and
cartilaginous bone growth)
Growth hormone acts on liver and bone (growth
plates)
Overproduction of (GH) will result in gigantism.
Or if occurs after long bone formation has
completed Acromegaly will occur
 Underproduction of (GH) will result in pituitary
dwarfism
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Growth Hormone
Thyroid stimulating hormone
 Controls
production of metabolic
regulatory hormones from thyroid
gland
Adrenocorticotropic hormone
 Controls
adrenal cortex production of
corticosteroid hormones
Follicle Stimulating Hormone
 females
– FSH promotes synthesis of
estrogen and development and growth
of follicles in ovaries to become
oocyte(s)
 males – FSH promotes production of
sperm in testes
Luteinizing Hormone
Luteinizing Hormone
 1)
females – promotes sex hormone production
and release of oocyte from follicle
 2) males – promotes sex hormone production
Posterior lobe of pituitary
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Anti-Diuretic Hormone (ADH) -VASOPRESSIN- causes collecting ducts of
nephron to re-absorb more water from
urine. Underproduction leads to diabetes
insipidus (dehydration)
Oxytocin- Causes contraction of
uterine smooth muscle (i.e. LABOR!!!)
Release (post-partum) causes
contraction of milk ducts in mammary
Intermediate pituitary
MELANOCYTE STIMULATING HORMONEtargets the melanocytes in skin, hair, and
eyes to make more melanin. More active in
pregnant women. (common in animals
which change fur color)
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Controlled by regulating hormones in
hypothalamus
Underproduction leads you susceptible to
sunburns
Pineal gland
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Produce the hormone melatonin- targets
all cells.
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Effects- circadian rhythms, protect vs free
radicals, inhibits reproductive functions
THYROID GLAND
Located ate the base of the throat just inferior
to the Adam’s apple
 Two large lobes joined by an isthmus
 Produces- Thyroxine and Calcitonin
Thyroxine- stimulates metabolismcontains iodine
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People with not enough iodine in their diet get
GOITERS. Negative feedback loop tells thyroid
to keep producing but lack of iodine makes the
molecule nonfunctional
Thyroid
Goiter
Thyroid Gland
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Hypothyroidism- Cretinism- “dwarfism”
occurs in early childhood
 In
adults results in MYXEDEMA- physical or
mental sluggishness
Thyroid Gland
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Hyperthyroidism- high
metabolic rate,
intolerance of heat,
rapid heartbeat,
nervous behavior
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GRAVE’s DISEASEthyroid enlarges and
eyes bulge
Thyroid gland
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CALCITONIN- decreases blood calcium
levels by causing calcium to be deposited
into bones
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Hyposecretion- lead to decalcification in
elderly adults
PARATHYROID GLAND
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PARATHYROID HORMONE- regulates
calcium level in blood- when low it
decalcifies bone to add to blood supply
- If blood calcium levels fall too low then
neurons become irritable and overactive.
-Hyperparathyroidism- causes massive bone
destruction-
THYMUS
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THYMOSIN- programs certain
lymphocytes
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Thymus stores “T cells” until they mature
Adrenal Cortex
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Mineralcorticoids- regulate salt and potassium in
the blood
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ALDOSTERONE- high levels in the blood reclaim
sodium and allow potassium out in urine
When sodium is absorbed then water will flow
smoother
Hyposecretion- ADDISON’S DISEASE- sodium and
water are lost from the body- skin appears bronze
and muscles become weak
Hypersecretion- excessive water and sodium retainedpotassium severely lost-
RENIN
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Enzyme produced by the kidneys that
controls the release of ALDOSTERONE
Adrenal Cortex
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CORTISONE- promote
normal cell
metabolism- resists
long-term stressors
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Have antiinflammatory and pain
inhibitors
HypersecretionCUSHING’S
SYNDROME- “buffalo
hump”
Adrenal Cortex
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ANDROGENS- male sex hormones
hypersecretion- masculinization regardless
of sex
-ESTROGEN- female sex hormonesproduction of female characteristics
ADRENAL MEDULLA
EPINEPHRINE (ADRENALINE) AND
NOREPINEPHRINEProlongs the effects of the sympathetic
nervous system
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Hyposecretion- no major effects
PANCREAS
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INSULIN- acts on all body cells and
increases their ability to take glucose in
through cell membrane
 Takes
glucose out of blood
 Without
insulin- glucose will be lost out urine
along with excess water- dehydrationDIABETES MELLITUS
 Too much insulin- leads to hypoglycemia
PANCREAS
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3 COMMON SIGNS OF DIABETES
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sugars
excessive urination
excessive thirst
hunger due to inability to take in
PANCREAS
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GLUCAGON- adds glucose to bloodstimulates liver to breakdown glycogen
into glucose
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Hyposecretion / hypersecretion- no
important disorders
Somatostatin- GH-IH- targets other cells
in the pancreas
inhibits insulin and
PANCREAS
glucagon secretion Stimulated by protein-rich meal
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Pancreatic polypeptide- targets gall
bladder- regulates gall bladder contraction
 Stimulated by protein-rich meal
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OVARIES
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ESTROGENS- stimulate secondary sex characteristics in
women-
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ESTROGEN AND PROGESTERONE- prepares the uterus
to receive a fertilized egg- Menstrual Cycle
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Prepares breasts for milk production
Helps maintain pregnancy
HYPOSECRETION- inhibits woman’s fertility
menopause
Hypersecretion- increased breast cancer and ovarian
cancer
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TESTES
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ANDROGENS- male sex hormones
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TESTOSTERONE- causes male sex
characteristics
 Production
of sperm
 Hyposecretion-
sterility
PLACENTA
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HUMAN CHORIONIC GONADOTROPINstimulates the production of more
estrogen and progesterone
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Home pregnancy tests test for Human
chorionic gonadotropin
PINEAL GLAND
MELATONIN- “sleep trigger” establishes
the day/night cycle
 Coordinates hormones of fertility
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KIDNEYS
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ERYTHROPOIETIN- targets the red bone
marrow to make more red blood cells-
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Overproduction- too many RBC which
will thicken the blood
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Underproduction- too few RBC- which
leads to ANEMIA