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