Transcript Endocrine system

ENDOCRINE SYSTEM
3 methods of communication
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Direct
Cells have direct connections to other cells and can send messenger molecules
Alternatively cells can communicate with themselves (autocrine)
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Paracrine
Signal is sent to nearby cells
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Ex. Neurons communicating with each other via neurotransmitters.
Response to signal is typically very quick and short-term.
Endocrine
Hormones produced in glands communicate with cells throughout the body.
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Response to hormones can be relatively slow, but long-lasting
Endocrine communication
• Two main types of hormone molecules
• Peptides
• Steroids
• Produced by glands which secrete them into the bloodstream
Peptide hormones
• Communicate with other cells by binding to receptors
on the surface of the cell
• This initiates processes inside the cell
• Example:
• Insulin is a hormone
• Binds to surface of cells
• Causes glucose transporters to move to the plasma
membrane
• Glucose is taken in by cells
Steroid Hormones
• Enter cells and find receptors inside target cells
• End result is a change in regulation of certain genes
• Remember genes are responsible for making proteins (the
functional molecules in our cells)
• Slower response than peptide hormones
• Example: Testosterone
• Causes sex cells to differentiate into the male
reproductive system during development
Hypothalamus
• The thalamus receives sensory information, relays
some to the hypothalamus.
• Hypothalamus monitors the body for temperature,
pH, other conditions.
• Hypothalamus signals pituitary gland if conditions
need to be corrected.
Pituitary gland
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The pituitary is the “master gland” that signals other glands to produce
their hormones when needed.
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The pituitary receives signals from the hypothalamus, and responds by
sending out the appropriate hormone to other endocrine glands.
Pituitary gland
Pituitary Hormone
Functions
Follicle-stimulating hormone
Stimulates egg maturation in the ovary and release of
sex hormones.
Lutenizing hormone
Stimulates maturation of egg and of the corpus luteum
surrounding the egg, which affects female sex
hormones and the menstrual cycle.
Thyroid-stimulating hormone
Stimulates the thyroid to release thyroxine.
Adrenocorticotropic hormone
Causes the adrenal gland to release cortisol.
Melanocyte-stimulating hormone
Stimulates synthesis of skin pigments.
Growth hormone
Stimulates growth during infancy and puberty.
Antidiuretic hormone
Signals the kidney to conserve more water.
Oxytocin
Affects childbirth, lactation, and some behaviors.
Other hormones
• Many other organs besides the endocrine
glands produce hormones.
• Kidneys produce several hormones that
regulate blood pressure, which is essential for
kidney function.
• The digestive system produces several
hormones that regulate appetite.
Disorders
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Type II diabetes (remember Type I from autoimmune diseases?)
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Instead of not producing enough insulin cells develop insulin resistance.
Insulin essentially doesn’t work as well as it should
The pancreas produces more insulin to compensate but can’t keep up
Glucose builds up in the blood
Complications:
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Higher risk of cardiovascular disease
Nerve damage – excess sugar damages nerve cells
Kidney damage
And many manymore
Hypothyroidism – low thyroid activity
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Symptoms
• Tired
• Weight gain
• Depression
• Cold sensitivity
• Dry skin and hair
• Muscle aches
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Causes
• Typically an autoimmune disorder (Autoimmune – self immunity, the body
attacks itself)
• Also cancer or treatment for overactive thyroid
Hypothyroidism
• Diagnosis
• Blood test measuring hormone levels
• Compares the levels of two hormones, thyroid-
stimulating hormone and thyroxine
• High levels of thyroid-stimulating hormone and low
thyroxine is a sign of underactive thyroid
Hypothyroidism
• Treatment
• Hormone replacement pills
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Typically for the rest of your life
• Complications
• Heart disease
• Fertility problems