The Endocrine System

The Nervous System’s Cousin
 Differentiate
between endocrine and
 Describe the structure and function of
various endocrine glands and their
corresponding hormones
 Determine how hormones are recognized by
receptors and can alter cellular function
 Differentiate between steroid and peptide
 Explain what negative feedback means
within the endocrine system
 2nd
greatest controlling
system of the body
 Works
closely with what
other system?
 Works
slowly by secreting
chemical messengers
called hormones
throughout the circulatory
system that tell the body
what to do
 Endocrine
glands- ductless glands that
produce hormones that release into blood or
lymph circulation
Pituitary, hypothalamus, thyroid, parathyroid,
adrenal, pineal, thymus, gonads, and pancreas
 Exocrine
glands- release their products at the
body’s surface or into body cavities through
Sweat and oil glands; pancreas; liver
 Chemical
messengers secreted by endocrine
glands that diffuse into the bloodstream and
act on target cells some distance away
 “Local
hormones” that function similarly to
hormones but are not technically hormones:
Paracrine – only affect neighboring cells
Autocrine – affect only the secreting cell (itself)
 Many
hormones, many functions
Growth and development
Nutrient, water, and ion balance
 Ongoing
Feedback loops
 What
does it mean to have a “hypo”
 What
does it mean to have a “hyper”
 Your
body wants to be in equilibrium to
function properly; when there are
hypo/hyper conditions, hormones are
released to bring the body back to normal!
 Disease/disordered
 What
can cause this to happen?
Problems with synthesis or secretion of the
Problems with the hormone’s receptor protein
 How
blood levels of hormones are regulated
by maintaining homeostatic function
 Negative
feedback mechanism
If you have high levels of leptin in your body,
what happens?
 High
levels of hormone in the blood stream
will “feedback” to the source and tell the
gland to stop producing the hormone
 Turns
itself off
 If
negative feedback shuts down hormone
production after a large amount is detected
in the blood stream… what does positive
feedback do?
Process of amplification where an increase in
hormones causes an increase in the response
The body goes further away from equilibrium
 Hormone
known to exhibit positive feedback:
Oxytocin stimulates uterine contraction in
Oxytocin promotes milk letdown in nursing
 Steroid
Made from
 Includes hormones
made in the
adrenal cortex
(cortisol &
 Includes hormones
made in gonads
(testosterone &
 Peptide
Consist of amines,
peptides, proteins
 Made from amino
What differences do
you notice between
peptide and steroid
hormone structure?
Steroid Hormones
Peptide Hormones
Steroid vs. Peptide Hormones
 Water
 Lipid soluble?
 Ability to pass through cell membrane?
 Site of formation of hormone-receptor
complex? (where do they bind?)
 How does it work?
 Half-life?
Insoluble in water
(doesn’t dissolve)
 Soluble in lipids (does
 Can pass through the
phospholipid cell
membrane but cannot
travel in the aqueous
bloodstream without
a protein carrier
Steroid Hormones
Soluble in water
 Insoluble in lipids
 Cannot pass through
the phospholipid cell
membrane on its own
but can travel in the
aqueous bloodstream
Peptide Hormones
complex binds in the
 This causes specific
genes to be activated
to make specific
proteins coded for by
the genes
 Long half-life
Steroid Hormones
complex binds on the
cell membrane
(cannot pass through)
 This causes a cascade
of events triggering a
1st messenger protein,
which triggers a 2nd
messenger, eventually
activating proteins to
alter cell activity
 Very short half-life
Peptide Hormones
Broken down into 3 parts
 Describe
the structure of the pituitary and
label which hormones are released in each
 Describe the function of the pituitary
 Recognize various pathologies related to
pituitary hormone imbalances
 Located
at the base of the brain where the
pituitary stalk attaches to the hypothalamus
 1 cm in diameter
 Anterior
 Intermediate Pituitary
Not as functional in humans
 Posterior
 Produces
melanin stimulating hormone (MSH)
 Stimulates melanocyte cells to produce
 What does melanin do?
Pigment in the skin and in portions of the eye
and brain
is increased in exposure to UV light
 Disappears
during fetal development, but its
cells become parts of the two remaining
Neural-endocrine hormones are produced in
hypothalamus and stored in posterior pituitary
Post. Pit. hormones are released upon
stimulation by hypothalamic neurons
Supraoptic nucleus (SON)
 Paraventricular nucleus (PVN)
Even though they are made in the hypothalamus,
the post. pit. hormones are named so because
that is where they enter the bloodstream
 Antidiuretic
hormone (ADH)
Sometimes called Vasopressin
 Oxytocin
Background info:
Diuretic- chemical that increases urine production
Antidiuretic- chemical that decreases urine formation
Peptide hormone
Released by the Post. Pituitary when SON is
How can ADH prevent urine production? What
organ may ADH target?
ADH produces an antidiuretic effect by reducing the
volume of water the kidneys excrete
Overall, regulates the water concentration of body
 Osmoreceptors
in the brain sense changes in the
osmotic pressure of body fluids
 When
dehydrated, concentration of blood
solutes (ions, salt, sugar) increases, which
increases osmotic pressure
Targets kidneys to reabsorb more water into the
Concentrates urine (low volume of urine, higher
blood volume)
Increases blood pressure by constricting
arterioles in kidneys to allow for more water to
be absorbed
 Drinking
too much water dilutes body fluids,
inhibiting ADH
 Diuretics
cause water to be flushed out of
the body through urine
 Can you think of any diuretics?
 Antagonists
 Thinking
of ADH
question: College students
typically drink excessive amounts of alcohol
and walk from bars back to their apartments.
Why is this dangerous in the winter? Think
about ADH!
 If
the SON is damaged lowering the secretion
of ADH…
What will happen?
 Pathology
called Diabetes Insipidus
Frequent urination; kidneys don’t reabsorb water
Excessive, continual drinking
Continual thirst
Not necessarily life threatening unless don’t
drink enough water
 Peptide
 Synthesized in the hypothalamus, released by
the Post. Pituitary when stimulated by the
paraventricular nucleus (PVN)
 Hormone involved in + feedback
 Made in significant amounts in childbirth and
nursing women
 Stimulates
uterine contractions in childbirth
& “milk letdown reflex” in nursing mothers
 Nursing mothers often get cramps while
nursing after childbirth due to high levels of
oxytocin released
 Synthetic oxytocin drugs are used to induce
labor by mimicing oxytocin (Pitocin)
 “Mother/Father Love hormone” or “Bonding
For relationships?
Boyfriend blues?... Oxytocin is not the cure
 Women with less oxytocin receptors in their brain
show not as many affectionate behaviors toward
significant other
For anorexia
Anti-anxiety drug possibility; help fight food fixations
For autism
Helpful in boosting emotional recognition
Still in the research phase
 Glandular
 Makes
tissue, purely endocrine function
many peptide hormones:
 Growth
Hormone (GH)
 Prolactin (PRL)
 Follicle Stimulating Hormone (FSH)
 Luteinizing Hormone (LH)
 Adrenocorticotropic Hormone (ACTH)
 Thyroid Stimulating Hormone (TSH)
 Function
in reproductive endocrinology
(follicle stimulating hormone)stimulates follicle development in female
ovaries & stimulates sperm production in
 LH
(luteinizing hormone)- triggers ovulation
in female ovary monthly & stimulates
testosterone production in males
 Infertility
of males and females
 Some fertility treatments increase levels of
 Multiple births due to increase in these
gonadotropic hormones causing multiple
ovulations a month
 Hormone
that controls metabolism, building
up muscles and uses glycogen & fats for
 Anabolic function
 Plays role in bone and skeletal muscle
 Hypo-GH
What does this mean?
Pituitary Dwarfism is hypo-GH in childhood
4 feet tall, proportional body
 Hyper-GH
What does this mean?
Gigantism is hyper-GH in childhood
8-9 feet tall, proportional body
Acromegaly is hyper-GH after long bone growth
has ended in adulthood; facial bones continue to
grow; non-proportional growth
 Gigantism
 Acromegaly
 Dwarfism
 Stimulates
and maintains milk production in
mother’s breasts after childbirth
 Inhibited
by dopamine (high levels of
dopamine = no milk production)
 Prolactinomas-
increase milk production; can
occur in males too
 Influences
the activity of the thyroid gland
by stimulating the release of T3/T4 (thyroid
 Regulates
the endocrine activity of the
adrenal cortex
And the Parathyroid Glands
 Describe
the structure and function of the
thyroid gland
 Describe the function of the T3/T4 thyroid
 Describe the function of the C cell’s
Calcitonin hormone
 Explain the function of the parathyroid gland
and secreted parathyroid hormone
 Recognize thyroid and parathyroid hormone
 Located
at the base of the throat below the
Adam’s apple around the esophagus
 Sticky colloid-filled follicles where thyroid
hormone is made
 C (parafollicular) cells is where calcitonin is
 T4
Thyroxine has 4 Iodines (the major form)
 T3
Triiodothryonine has 3 Iodines
 Both
T3 and T4 have similar functions
 T3 is five times stronger than T4
 Thyroid
collects iodine in order to make
T3/T4 hormones
Where do you get iodine?
 Function
Controls the rate at which glucose is used for
body heat and chemical energy
If a lot of thyroid hormones are made,
metabolism will increase
 Basal
in cellular metabolism
metabolic rate (BMR)
Determines how many calories the body must
consume at rest in order to maintain life
 Every
cell in the body is a target for T3/T4
(the thyroid hormones)
 Draw
it out
Anterior pituitary releases TSH
TSH goes to Thyroid
Thyroid releases T3/T4
How do they feedback?
 Hyperthyroid:
Goiter forms due to
overactive thyroid
 Swelling of eye socket
tissue  bulging eyes
 Irritable, hyperactive,
insomnia, high body
temp., ravenous
 Grave’s Disease
disorder) can be a
cause of hyperthyroid
 Too
little T3/T4:
Possible cause is Iodine deficiency
Common before “iodized” salt
Goiter due to constant TSH in thyroid
Weight gain, lowered body temp., lethargy,
slower pulse
 Protein
 Made in the C cells in the connective tissue
between the thyroid follicles
 Decreases
blood calcium levels by putting
calcium deposits in bones
 If blood calcium levels increase, CT is
released to lower them again
tiny yellow glandular tissue masses on
outside of the thyroid gland
 Secretes parathyroid hormone (PTH), a
protein hormone, which is another regulator
of blood calcium levels
works antagonistically with CT… what
does this mean?
 Functions in raising calcium levels in the
blood if they drop below a certain level by
causing osteoclasts in bone to break down
bone matrix to release calcium
 PTH also stimulates kidneys and intestines to
absorb more calcium from food
Severe hyperparathyroidism- breakdown of bone
matrix, increased osteoporosis, and broken
brittle bones
 Severe hypothyroidism results in death due to
low Ca2+ levels
Nervous system failure; uncontrollable spasms
Can actually remove parts of PTH tumors and
place remaining healthy parathyroid gland on
the skin and it will function normally!
 Low CT in elderly adults (possible link to
Take salmon calcitonin supplements
Consisting of the Adrenal Cortex and
Adrenal Medulla
 Located
on top of the kidneys
 Adrenal cortex- outer portion
of adrenals that is purely
Makes steroid endocrine
 Adrenal
medulla- inner region
consisting of neuroendocrine
Makes neurotransmitters
epinephrine and norepinephrine
 Makes
3 main groups of steroid hormones
called corticosteroids
Sex steroids
Cannot survive
without adrenal
 Functions
in regulating salt concentration in
the blood (Na+ and K+)
Higher aldosterone leads to increased absorption
of Na+ into blood and release of K+ into urine
 What
organ do you think this hormone
Kidneys- selectively absorb ions or allow them to
be flushed out in urine
 Help
regulate water and electrolyte balance
in blood
 Hyperaldosterone
water & Na+ retention
Abnormally high amount of water and sodium in
blood leads to HIGH blood volume and HIGH
blood pressure
Heart has to work harder!
Usually due to a tumor; must be removed
 Addison’s
Sodium and water are lost,
electrolyte imbalance, weakened
muscles, tiredness, bronze skin
Low blood glucose, dehydration, low
blood pressure
Can lead to deficiency in
glucocorticoids (cortisol)
Lethal within days without
treatment of adolsterone and
cortisol hormone replacement shots
Excess unused ACTH
leads to buildup of
sometimes called the stress
 Produced
in the middle adrenal cortex
 Without cortisol, a person will not survive
 Raises
blood glucose levels
Liver breaks down excess amino acids to glucose
Promotes fatty acid breakdown (rather than
glucose break down) for metabolism
 Suppresses
immune system by counteracting
inflammatory response
Hydrocortisone Cream- reduce swelling & itching
Steroid injections for extreme cases of
swelling/immune responses
Poison ivy, eczema, swollen/bulged disks in back, etc.
 Organ
transplant patients receive high doses
of cortisol-like steroids (dexamethasone) to
prevent immune response against foreign
 Cushing’s
Disease- HYPERcortisol disorder
More likely to develop Diabetes due to high blood
High blood pressure (due to high blood glucose)
Fat deposits at waist, buffalo hump, moon face
Higher susceptibility to infection
Normally accompanied by an excess in
adolsterone as well
 Extreme
Addison’s disease is also linked to
low cortisol
Usually when low in adolesterone, low in cortisol
 Hypoglycemia
(low blood glucose levels)
 Inability to deal with stress
 Both
male and female sex hormones
produced by innermost adrenal cortex
 Sometimes called sex steroids
 Androgens- male sex hormones are produced
in both males and females but at a higher
level in males
 Estrogens- female sex hormones produced in
both sexes but higher quantity in females
 Secretes
epinephrine and norepinephrine
Work together to do the same job
 Increase
heart rate, breathing rate, blood
glucose level, elevate blood pressure, and
decrease digestion
 Sympathetic nervous system stimulates
adrenal medulla
 Fight or flight
The Sex Hormones
 Most
of the androgens, like testosterone, is
produced by the testes in males
 Most of the estrogen and progesterone is
produced by the ovaries in females
 Made
in the testes
 Increase
primary and secondary sex
 Testosterone plays role in building muscle
Anabolic steroids
 If
females overproduce androgens in adrenals
or can’t convert testosterone to estrogen,
can show characteristics of maleness
Masculinization regardless of the sex
 Made
in the ovaries
 3 types
Normal estrogen, 1 in pregnancy,
1 in menopause
 Primary
and secondary sex
characteristics in females
 Necessary for egg development
 Progesterone is necessary for
 Synthetic
progesterone called progestin in
birth control pills
 Taken daily with makes the body think that it
is pregnant thus ovulation ceases
Near the end of monthly cycle, if egg is not
fertilized and implanted in uterus, progesterone
levels lower and the cycle starts again
If levels do not decrease, the cycle will not start
 Male
birth control by regulating hormones
Block FSH receptors?
Block FSH secretion?
Possibly interfere with inhibin
Another male hormone involved in sperm
A review from semester 1
 Exocrine-
digestive enzymes
 Endocrine- releases
 Posterior
to stomach
and attached to first
section of small
intestine (duodenum)
 Pancreatic
islets- (Islets of Langerhans)
endocrine portion of the pancreas that
consists of two types of cells closely
associated with blood vessels
Alpha cells
Secrete glucagon
Beta cells
Secrete insulin
 Stimulates
liver to break down glycogen into
glucose to raise blood sugar
Epinephrine can also do this (not as efficiently)
 Low
blood glucose triggers the release of
 Glucagon
prevents hypoglycemia between
meals and during exercise
 Stimulates
the liver to MAKE glycogen from
glucose and to uptake glucose from the blood
stream into cells
 Lowers blood glucose levels
 Prevents hyperglycemia
 High blood glucose levels trigger the release
of insulin
 Glucagon
 Lack
of insulin or the inability of cells to
recognize it
 Insulin deficiency disrupts carbohydrate,
protein, and fat metabolism
 Symptoms- hyperglycemia leading to kidneys
excreting sugar in the urine; sweet breath;
polydipsia (extreme thirst); weight loss;
hunger increase; ketoacidosis (low blood pH)
 Usually
before the age of 20 and is
autoimmune where the immune system
attacks the beta cells of pancreas (so they
cannot make insulin)
 Insulin dependent- shots/pumps are required
 Islet
replacements can be placed in liver
Procedure is risky and rarely successful; thus
hormone replacement is the best choice for
 Beta
cells produce insulin but the body cells
lose the ability to recognize it
 85-90% of people with diabetes have Type 2
 Usually correlated with overweight people
over the age of 40
 Treatment: diet, exercise, oral drugs to
control glucose levels, possible insulin shots