The
Endocrine
System
What is the Endocrine System?
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The endocrine system is the
collection of glands, all of which
secrete different types of hormones
that control metabolism, growth and
development, tissue function, sexual
function, reproduction, sleep and
mood, along other things.
Greek Meaning:
endo- within
crinis- secrete
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Glands
The endocrine system is composed of 8
major glands: the hypothalamus, pituitary
gland, thyroid gland, parathyroid gland,
adrenal glands, pineal gland, reproductive
glands, and pancreas
Glands select and remove materials from the
blood, process them, and secrete the
finished chemical product for use somewhere
in the body
The glands are controlled directly by
stimulation from the nervous system as well
as by chemical receptors in the blood and
hormones produced by other glands.
These glands help to maintain the body’s
homeostasis
A group of glands that signal each other in
sequence are usually referred to as an axis
Intro to the Endocrine System
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The roles of hormones in selecting target cells
and delivering the hormonal message
Almost every organ in our body is affected
by the endocrine system
The endocrine system sends signals
throughout the body, similar to the nervous
system, but instead of immediate responses
triggered by the nervous system, responses
can take a few hours to weeks in the
endocrine system
The endocrine system gets some help from
organs such as the kidney, liver, heart and
gonads, which have secondary endocrine
functions and secrete certain hormones.
https://www.youtube.com/watch?v=gjmS4_7kvDM
Hormones and Receptors
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The endocrine system uses chemical
messengers called hormones that are
transported by the circulatory system (blood).
They act on target cells that may be anywhere
in the body
Target cells have receptors that are specific
to the signaling molecules. The binding of
hormones to the receptors on or within the
target cell produces a response by the target
cell.
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Hormones and Receptors cont.
Endocrine glands make hormones.
The glands release hormones directly into the blood or lymph system. The
hormones then travel into the blood to tissues and organs where they can attach
to specific cell sites called receptors.
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By attaching to receptors, hormones trigger various responses in the tissues
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The receptors are specific to the signaling molecules.
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The binding of hormones to the receptors on or within the target cell produces a
response by the target cell
Classes of Hormones
Water-soluble hormones: include the peptide and
amino acid hormones (insulin, epinephrine,
HGH, and oxytocin). These hormones are soluble
in water. They are unable to pass through the
phospholipid bilayer of the plasma membrane
and are therefore dependent upon receptor
molecules on the surface of cells. When this cell
binds to a receptor molecule on the surface of
the cell, it triggers a reaction inside the cell.
Lipid soluble hormones: include the steroid
hormones (testosterone, estrogens,
glucocorticoids, and mineralocorticoids). These
hormones are able to pass directly through the
phospholipid bilayer of the plasma membrane
and bind directly to receptors inside the cell
nucleus because they are lipid soluble. They are
able to directly control the function of a cell
from these receptors which often trigger the
transcription of particular genes in the DNA to
produce “messenger RNAs” that are used to
make proteins that affect the cell’s growth and
function.
Steps of Endocrine Functions
1. The nervous system sends impulses primarily
to the brain, which triggers the function of the
endocrine system
2. Specific hormones are secreted based on the
messages to the brain
3. The hormones travel through the bloodstream
across the plasma membranes of cells
4. Corresponding target cells have receptors
which only receive certain hormones (this is
called specificity)
5. Cells have special proteins which bind to
hormones, controlling how much of the
hormones is received
General Function
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Maintenance of homeostasis in terms of balanced
hormone levels and metabolic activity
● Negative Feedback System
(most common)
○ Thyroid hormones
● Positive Feedback System
○ Childbirth
Endocrine System vs Nervous System
Endocrine System
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dispersed through the body
depends on receptors in target cells
slow signals/process
long lasting effects
Nervous System
● precise arrangement
● depends on anatomical placement
● rapid signals/ response
● short-term effects
● influences endocrine output
influences CNS output
Both systems enable cells to communicate with others by
using chemical messengers
Hormone Responses
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Environmental condition to hormone
o Some glands respond immediately to homeostatic changes
Hormone to gland
o Automatic hormone secretion maintenance
Hormone Regulation
● Nervous System- triggers hypothalamus
● Number of receptors- controls uptake
● Tropic Hormones- “two birds with one stone”
● Nutrition- maintenance of metabolic rate
Homeostatic Control
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Metabolic rate
Growth hormone
Blood glucose levels
Blood calcium levels
Stress
Hypothalamus
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Located on the undersurface of the brain, below the thalamus
and above the pituitary gland. The hypothalamus is
approximately the size of a pea.
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Responsible for maintaining homeostasis, hormone production
and controls the pituitary gland and many other glands.
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The hormones produced in the hypothalamus regulate body
temperature, thirst, hunger, sleep, mood and sex drive.
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There are two sets of nerve cells that produce hormones in the
hypothalamus. The first set sends the hormones to the
posterior lobe of the pituitary gland and out into the
bloodstream. These hormones include the anti-diuretic
hormones and oxytocin. The second set of nerve cells produces
stimulating hormones that go to the anterior lobe of the
pituitary gland which help regulate the hormones.
Pituitary Gland
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Very small gland located in the center of the skull. It is
protected and surrounded by the sphenoid bone.
There are two parts of the pituitary gland: the anterior
pituitary gland (adenohypophysis) and the posterior pituitary
gland (neurohypophysis).
The adenohypophysis is a hormone producing gland that is
made up of up granular epithelial tissue. The anterior pituitary
glands produces many hormones: the human growth
hormone,follicle-stimulating hormone, luteinizing hormone,
prolactin,adrenocorticotropic hormone, and melanocytestimulating hormone.
The neurohypophysis is nervous tissue extended from the
hypothalamus that stores and releases hormones produced in
the hypothalamus.
Thyroid
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Butterfly shaped gland which lies in front of the trachea just below
the larynx.
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The two thyroid hormones, thyroxine and triidothyronine are
produced from iodine in food.
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These hormones are stored and released as needed, they help
regulate and produce adrenaline, epinephrine, dopamine and
metabolism.The thyroid gland also helps regulate calcium levels in
the body.
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The levels of hormones secreted are controlled by the pituitary
gland’s thyroid-stimulating hormones, which are controlled by the
hypothalamus.
Parathyroids
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There are four parathyroid glands which are located in the neck
behind the thyroid.
The main job of the parathyroid gland is to control the calcium.
If calcium levels goes down, the parathyroid gland recognizes
this and will make parathyroid hormone (PTH) which will go to
the bone where calcium will be taken out and put into the
blood.
If the calcium level is too high, then it will make a less amount
of PTH or will stop making it all together.
Adrenal Glands
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Triangle shaped, located on top of each kidney and controlled by the
pituitary gland.
The outer adrenal cortex produces the hormones aldosterone and
cortisol.
Aldosterone balances potassium and calcium which manages a persons
blood pressure.
Cortisol works along with adrenaline and noradrenaline which help
regulate your body to stress. Along with that, cortisol helps regulate
blood pressure, sugar levels and metabolism.
Pineal Gland
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Referred to as the “Third Eye”, the pineal gland is a small
pinecone shaped organ inside the brain that secretes the
hormones melatonin, serotonin and dimethyltryptamine(DMT).
Melatonin and serotonin involve sleeping and meditative states
and the emotional states of well being.
The DMT effects range from time dilation, time travel, and
encounters with spiritual beings from other dimensions.
Reproductive Glands
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The two major reproductive glands include the ovaries and the testes.
The main source of sex hormones in males, androgens, are secreted by
the testes which are located in the scrotum.
The most important male reproductive hormone is testosterone which
have an impact on many male characteristics such as the growth of facial
hair and also sperm production.
In females, the ovaries which are located on both sides of the uterus;
produce estrogen, progesterone and eggs.
These hormones control the female characteristic development such as
breast growth.
Pancreas
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Located in the upper abdomen and consist of two separate
glands, the digestive exocrine gland and the hormone
producing endocrine gland.
The exocrine gland allows the pancreas to excrete
enzymes to break down proteins, carbohydrates, lipids
and nucleic acids in food.
The endocrine gland allows the pancreas to secrete the
hormones insulin and glucagon which help control blood
sugar levels.
Endocrine System Disorders
What is an endocrine system disorder?
a medical condition creating a hormonal imbalance
Two groups of endocrine disorders:
-disease results from hormone imbalance (too much or too little of a
hormone)
-develops due to lesions such as nodules or tumors which could or
could not affect hormone levels
Endocrine System Disorder Affects:
-mood
-growth and development
-sexual function
-reproduction
Hormone Imbalances
hormone- chemical messenger for the body
-even tiny amounts of changes in hormone levels can greatly affect
the body
How do hormone imbalances occur?
- There may not be enough receptors, or binding sites, for the
hormones. There may be a problem with regulating hormones in
the blood stream.
-due to problem with feedback from endocrine system, disease,
genetic disorder, infections, injury or tumor of an endocrine
gland, etc.
hypersecretion- overproduction of hormone from a gland
hyposecretion- underproduction of a hormone from a gland
Evaluating Disorders
Pituitary Gland Disorders: can disrupt hormone production and normal functioning
Thyroid Gland Disorders: affects the sympathetic nervous system and normal metabolism
Parathyroid Gland Disorders: affects calcium levels in bone, blood, nerves, muscles, and other tissues
Adrenal Gland Disorders: affects bone calcium levels, blood pressure, metabolism, and mental status
Pancreatic Gland Disorders: includes diabetes, disrupts hormones such as insulin
Types of Disorders
diabetes- most common endocrine system disorder; affects
metabolism; pancreas doesn’t produce enough insulin
adrenal insufficiency- adrenal gland releases too much hormone;
symptoms: fatigue, upset stomach, dehydration, skin changes
gigantism- pituitary gland produces too much growth hormone causes
children to grow too fast
hypothyroidism- not enough thyroid hormone is produced; symptoms:
fatigue, dry skin, depression
hyperthyroidism- body produces too much thyroid hormone;
symptoms: fast heart, weight loss, fast heart rate, sweating, and
nervousness
Cushing's disease- overproduction of pituitary gland hormone which
leads to overactive adrenal gland; causes swelling and obesity
hypopituitarism- pituitary gland releases too little or no hormone; can
be caused by many different diseases; symptoms: fatigue, weight
loss
Types of Disorders
multiple endocrine neoplasia I and II- a rare genetic condition that causes tumors
of the parathyroid, adrenal, and thyroid glands; leads to overproduction of
hormones; symptoms include abnormal bone structure, being tall and slender
polycystic ovary syndrome- overproduction of androgens; interferes with
development of eggs and release from ovaries
precocious puberty- abnormally early puberty; occurs when glands tell body to
release hormones too soon
thyroid cancer- cancer begins in thyroid gland, grows, and forms a tumor
metabolic disorder- abnormal chemical reactions disrupt metabolic rate; could
lead to dysfunction of the liver and pancreas (diabetes falls under this
category)
dwarfism- pituitary gland does not produce enough growth hormone; reduces
muscle and bone growth
acromegaly- overgrowth of the flat bone of the face due to excessive growth
hormone
acromegaly
Testings and Treatments
endocrinologist- specially trained in endocrine
system
-symptoms vary widely so can be difficult to
diagnose
-modern treatment is effective
-mild cases often don’t require treatment
-can be treated by correcting hormonal imbalance
-most common symptoms are fatigue and
weakness
-synthetic hormones can be administered
-blood and urine tests can be used to check
hormone levels
-surgery or radiation can be used in cases of tumors
or nodules
-imaging testing can be used to locate tumors
Risk Factors
- elevated cholesterol levels
-family history of an endocrine disorder
-inactivity
-poor diet
-recent surgery/treatment
-pregnancy
Reduce the Risk by:
-eating a well-balanced diet
-get adequate exercise
-lowering stress levels
-getting enough sleep
Works Cited
http://www.livescience.com/26496-endocrine-system.html
http://www.innerbody.com/image/endoov.html
http://www.pamf.org/endocrinology/services/faqs.html
http://www.healthgrades.com/procedures/endocrine-disorders
http://www.endocrineweb.com/
http://www.ssa.gov/disability/professionals/bluebook/9.00-Endocrine-Adult.htm
http://www.physiologyinfo.org/mm/What-is-Physiology/Endocrine/Diseases-of-the-Endocrine-System.html
http://www.hormone.org/diseases-and-conditions
http://www.pennmedicine.org/health_info/body_guide/reftext/html/endo_sys_fin.html#homeostatic
http://arbl.cvmbs.colostate.edu/hbooks/pathphys/endocrine/basics/control.html
http://www2.estrellamountain.edu/faculty/farabee/biobk/biobookendocr.html
http://health.howstuffworks.com/human-body/systems/endocrine/endocrine-system-ga.htm
http://faculty.stcc.edu/AandP/AP/AP2pages/Units14to17/endocrine/hormonal.htm
http://www.innerbody.com/image/endoov.html
Works Cited Continued
http://themindunleashed.org/2013/09/activating-your-pineal-gland.html
http://www.healthline.com/human-body-maps/hypothalamus#5/3
http://www.innerbody.com/image/endo01.html#full-description
http://www.webmd.com/a-to-z-guides/thyroid-gland
http://www.healthline.com/human-body-maps/thyroid-gland#3/7
http://www.healthline.com/health/adrenal-glands#Definition
http://www.emedicinehealth.com/anatomy_of_the_endocrine_system/page8_em.htm
http://parathyroid.com/parathyroid.htm
Video
https://www.youtube.com/watch?v=gjmS4_7kvDM