Transcript Endocrine System What is the endocrine system?

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Second great controlling system of the body
Body system that contains internal organs that
secrete hormones.
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Slowly acting chemical messenger that is
released into the blood
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So glad you asked that question!
Target cells or target organs
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Location where a given hormone affects
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Hormones cause certain changes.
What are these changes?
Changes in plasma membrane permeability or
electrical state
 Synthesis of proteins or certain regulatory molecules
(enzymes) in the cell.
 Activation or inactivation of enzymes
 Stimulation of mitosis
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Hormones control all activities in the body
They alter or change functions of cell to get a
response
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Steroidal Hormones
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Nonsteriodal hormones
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Insoluble in water, carried in the blood and released
near the vicinity of the target cell
Unable to enter target cells and instead bind to
receptors situation on the target cell’s plasma
membrane
Prostaglandins
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act locally, affecting only the organ where they are
produced
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Negative feedback
The chief means of regulating blood levels of nearly
all hormones
 Triggered by some internal or external stimulus
 Rising hormone levels inhibit further hormone
release
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In other words, a stimuli triggers hormone
production… then that hormone may either
stimulate or inhibit other hormones
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Pituitary
Thyroid
Parathyroid
Adrenal
Pineal
Thymus
Pancreas
Gonads
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Structure
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Size of grape
Located at the base of
the brain
Attached to the
hypothalamus
2 parts
 Anterior pituitary
 Posterior pituitary
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Function
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Often called the
“master gland”
because of its great
influence on the body
organs
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Prolactin (PRL)
Stimulates milk production in women after childbirth
 Can affect sex hormone levels in men and women
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Growth hormone (GH)
Stimulates growth in childhood
 Important for maintaining healthy body composition
 In adults, important for muscle mass, bone mass, and fat
distribution
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Adrenocorticotrophin (ACTH)
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Stimulates production of cortisol (“stress hormone”) by
adrenal gland. Helps maintain blood pressue and blood
glucose levels
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Thyroid stimulating hormone (TSH)
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Lutenizing homone (LH)
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Stimulates thyroid to produce thyroid hormones
Thyroid hormones – regulate metabolism, energy,
growth, and development
Regulates testosterone in men and estrogen in
women
Follicle Stimulating hormone (FSH)
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Promotes sperm production in men
Stimulates ovaries to release eggs (ovulate) in
women
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Oxytocin
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Causes milk letdown in nursing mothers and
contractions during childbirth
Antidiuretic hormone (ADH)
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Regulates water balance
If not secreted properly can lead to kidney problems
and too much sodium
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Structure
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Small gland in back
of neck
In front of trachea
and below Adam’s
apple
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Function
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Controls metabolism
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Thyroxin
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Increase rate at which cells release energy from carbs
Calcitonin
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Regulates the blood concentration of calcium
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Hypothyroidism
Stunted growth
 Mental retardation
 Sluggish
 Weight gain in adults
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Hyperthyroidism (Grave’s disease)
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Restlessness
Weight loss
Anxiety
Can cause Goiter (enlarged thyroid)
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Structure
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Behind thyroid
Four tiny glands
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Function
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Help maintain
calcium and
phosphorus levels
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Parathyroid hormone (PTH)
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Takes calcium from bones to make it available in the
blood
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Hyperparathyroidism
Can be caused by a tumor
 Increases PTH secretion
 Bones soften
 Too much calcium can cause kidney stones
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Hypoparathyroidsm
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Too little PTH
Too little calcium affects nervous system
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Structure
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2 organs… 1 located
above each kidney
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Function
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Outer portion called
adrenal cortex and
are essential for life
Inner portion is the
adrenal medulla and
are not essential for
life
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Epinephrine & Norepinephrine
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Increased heart rate, breathing rate, elevated blood
pressure (fight or flight response to stress)
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Aldosterone
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Cortisol
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Helps kidneys conserve sodium and excrete
potassium, maintaining blood pressure
Keeps blood glucose stable
Adrenal Sex Hormones
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Androgens (male) and estrogens (women)
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Cushing’s Syndrome
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Hypersecretion of cortisol
Blood glucose remains high, retains too much
sodium, puffy skin, masculinzing effects in women
Addison’s Disease
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Hyposecretion
Decreased blood sodium, dehydration, low blood
pressure, increased skin pigmentation
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Structure
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Large gland behind
stomach
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Function
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Helps body maintain
healthy blood sugar
levels
Contains islands of
cells called islets of
Langerhans which
secrete glucagon and
insulin
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Glucagon
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Stimulates liver to break down glycogen, raises
blood sugar
Insulin
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Decreases blood sugar concentrations, affects the
uptake of glucose cells
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Diabetes Mellitus
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Results from an insulin deficiency, blood sugar rises
and excess is excreted in the urine
Type I
 Insulin dependent; often inherited immune disorder
that destroys pancreatic cells
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Type II
 Can be controlled with diet and exercise
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Hypoglycemia
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Low blood sugar; can be caused by too much insulin
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Located between the cerebral hemispheres
Secretes melatonin
Important for maintaining Circadian rhythums
(light and dark activity)
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Large in young children
Gradually shrinks with age
Secretes thymosins – important to immune
function
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Testes and ovaries
Testosterone, progesterone, estrogen