Download Hormones

Endocrine System
By Debra Kuhn & Katrine Viscaya
What is the endocrine system?
• The word Endocrine derives from Greek origin
• The endocrine system is the collection of glands in
which each gland secretes a different type of
hormone that regulates:
• Metabolism
• Growth & Development
• Tissue Function
• Sexual Function
• Reproduction
• Sleep & Mood
• Ect.
What are hormones? What do
they influence?
Hormones: They are substances
secreted by endocrine glands into the
internal environment.
Influences: They diffuse from the
interstitial fluid into the bloodstream
and then act on target cells. They
regulate physical and chemical
processes. They may act on several
organs throughout the body.
Exocrine vs. Endocrine
Exocrine
Endocrine
• These glands secrete
products into ducts that
open onto surfaces (outside
environment)
• They have ducts to carry
hormones
• Sub-classifications:
Multicellular and Unicellular
• Multicellular glands include:
• Holocrine Glands
• Apocrine Glands
• Merocrine Glands
• Glands from this system
secrete their products into
tissue or blood (Inside the
Body).
• These glands are ductless
• The response is slower
because hormones travel
through blood
• The duration of the response
in motion is longer because
kidneys filter blood.
What makes up the Endocrine
System
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Hypothalamus
Pituitary Gland
Thyroid
Parathyroid
Adrenal Glands
Pineal Body
Reproductive (Ovaries and Testes)
Pancreas
Thymus
Regulation of Hormone Secretion
Every time a Hormone is secreted, it is due to Negative Feedback
Mechanisms. These mechanisms include
1.
The Hypothalamus: The Hypothalamus regulates anterior
pituitary glands release of hormones that tell other Endocrine
glands to release their hormones.
2.
The Nervous System
3.
The Changing level of substance in plasma: Another group of
glands responds directly to changes of the composition of the
internal environment
Nervous System Explained
• The Nervous System stimulates some
glands directly which then release
hormones to the target cells that cause
the action of hormone response.
Steroid vs. Non-steroid
Steroid
• Soluable (Soluable to Lipids so they can diffuse into cells easily)
• The Steroid Hormone binds a specific Hormone Molecule which
is the receptor for that Hormone
• Hormone Receptor Complex binds within the Nucleus to
particular regions of the target cells DNA
• This activate Transcription
• RNA molecules leave the Nucleus and enter cytoplasm
• mRNA associate with Ribosomes to direct the synthesis of
specific proteins
Steroid Vs. Non-Steroid
Non-Steroid
• A hormone binds its receptor
• This hormone receptor complex activates a protein called “G”
Protein
• The “G” Protein activates the enzyme Adenylate Cyclase
• Activated Adenylate Cyclase catalyses the circularization if ATP
in the Cytoplasm into cAMP
• cAMP activates another set of enzymes called Protein Kinases
which transfer Phosphate group from the ATP to their substrate
molecule
1. The Hypothalamus
• Location: Above the brain stem
• Controls the release of the 8 major hormones
• Controls body temperature, Food and Water
intake, hunger, thirst, sexual behavior, daily cycles
in psychological state, and the meditation of
emotional responses
2. Pituitary Gland
• Location: Beneath the Hypothalamus
• “Master Gland” – Most important gland of the
Endocrine System
• Hormone production
• Divided into two parts (Anterior and Posterior)
• Controls secretion of Endorphins
• Also controls Ovulation & Menstrual Cycle for
women
3. Thyroid Gland
• Location: Frontal part of Lower neck (Butterfly
Shape)
• Produces Thyroxine & Triiodothyronine = controls
rate of cell burning of food (energy)
• Metabolism
• Helps kids/teens bone grow and develop
• Develops the brain and nervous system in kids
4. Parathyroid Gland
• Location: Attached to Thyroid
• Releases Parathyroid Hormones =
regulates level of calcium in blood with
help of calcitonin (produced in Thyroid)
5. Adrenal Gland (Two Parts)
Location: On top of each Kidney
Outer (Adrenal
Cortex)
• Produces
Corticosteroids =
Regulates salt and
water balance in the
body, its response to
stress, metabolism,
immune system, and
sexual development
and function
Inner (Adrenal
Medulla)
• Produces
Catecholamines =
(Adrenaline), this
increases blood
pressure and heart
rate when the body
experiences stress
6. Pineal Gland
• Location: Middle of the Brain
• Secretes Melatonin = Regulates sleeping Schedule
(when you sleep at night and when you wake up in
the morning)
• Involved in daily biological cycles
7. Reproductive Glands
Males
• Gonads are main
source of sex
hormones
• Location: Testes in
Scrotum
• Secrete hormones
called androgen
Females
• Gonads are main
source of sex
hormones
• Location: Ovaries in
the Pelvis
• Secrete hormones
estrogen and
progesterone
8. Thymus
• Location: Behind Sternum & Between lungs
• This Gland is only active until puberty, and after
puberty it starts to shrink and is replaced by fat
• This gland stimulates the development of T cells =
• T cells are a type of white blood cells which helps
protect the body from infection and viruses
9. The Pancreas
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Location: Behind the Stomach
Two main functions:
exocrine function - helps in digestion
endocrine function - regulates blood
sugar
Hormones Released by Glands
Regulation of Hormone Secretion
• Hypothalamus regulates the anterior pituitary
gland’s release of hormones that stimulate
other glands to release.
• Nervous system stimulates some glands
directly (i.e. the adrenal medulla which
secretes hormones in response to
sympathetic nerve impulses)
• Other glands respond directly to changes in
the internal environment (i.e. blood glucose
level so pancreas secretes insulin or
glucagon)
Negative Feedback
Mechanisms
Cycle:
1.
2.
3.
4.
5.
Stimulus (ex. Blood
Glucose)
Receptors (ex. Beta Cells)
Control Center (Nerve
cells in Brain)
Effector (Insulin)
Response (Blood Drops)
Diseases
• Diabetes
•
Body does not process glucose properly, due to lack of insulin or
the body is not working effectively with the insulin
• Hypothyroidism
•
Thyroid gland doesn’t produce enough thyroid hormone, which
may cause many body functions to slow or shut down completely
• Hypoglycemia
•
Low blood glucose or low blood sugar, occurs when blood glucose
drops below normal. Typically happens as result to diabetes
treatment because too much insulin is taken
• Hormones can also impact bones, in diseases such as
osteoporosis and osteomalacia (rickets) in which bones soften