Download Endocrine System

Endocrine
System
Unit 6
Endocrine System
…coordinates
and controls the activities of the body
• Regulates:
– extracellular fluid
– metabolism
– biological clock
– contraction of cardiac & smooth muscle
– glandular secretion
– some immune functions
• Controls growth & development
• Regulates reproductive system
Endocrine System vs. Nervous
System
Endocrine System
•
•
•
•
•
hormones
far from site of release
cells throughout body
seconds - hours - days
long duration
Nervous System
•
•
•
•
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neurotransmitters
close to release site
muscles, glands, neurons
milliseconds
brief duration
Hormones and Glands
Hormones:
Chemical substances
that are produced in
one part of the body
and transported by
the blood to
influence activities
in another part of the
body
Endocrine vs. Exocrine
Endocrine
Exocrine
• hormones into blood
• pituitary, thyroid,
parathyroid. adrenal, pineal
• secondary function
• hypothalamus, thymus,
pancreas, testes, ovaries,
kidneys, stomach, GI,
skin, heart, & placenta
• ducts
• cavity/surface
• sweat, oil, mucous,
digestive glands
Hormone Activity and Cellular
Response
• A given hormone affects only target
cells
• Hormone receptors develop as a cell
differentiates
• Different cells may respond in
different ways to the same hormone
• Some hormones are present much of
the time, while others appear only
sporadically
• The amount of a circulating hormone
is usually governed by negativefeedback control
• Hormones are usually broken down
rapidly
• A hormone can increase the rate at
which other substances enter or
leave the target cell
• A hormone can stimulate a target
cell to synthesize enzymes,
proteins, or other substances
• A hormone can prompt the target
cell’s machinery to activate or
suppress existing cellular enzymes
Hormone Chemistry
1.
Steroid hormones – fat-soluble molecules (made from cholesterol)
•
Sex hormones groups: estrogens, androgens and progesterones.
• Males and females make all three, just in different amounts.
• Steroids pass into a cell's nucleus, bind to specific receptors and genes
and trigger the cell to make proteins.
• Steroid hormones must attach to transport proteins synthesized by liver
• improve transport by making them water-soluble
2.
Amino acid derivatives – water-soluble molecules derived from amino acids
• Epinephrine, insulin, growth hormone.
• These hormones are stored in endocrine cells until needed.
• They act by binding to protein receptors on the outside surface of the cell.
The binding alerts a second messenger molecule inside the cell that
activates enzymes and other cellular proteins or influences gene expression.
• Regulate such processes as metabolism, lactation, growth and reproduction.
•
Amino Acid hormones circulate in ‘free’ form in blood
Steroid Hormone
Action
Amino Acid
Hormone Action
Hormonal Interactions
• Permissive effect
– a second hormone, strengthens the effects of the first
ex. thyroid strengthens epinephrine’s effect upon lipolysis
• Synergistic effect
– two hormones acting together for greater effect
ex. estrogen & LH are both needed for oocyte production
• Antagonistic effects
– two hormones with opposite effects
ex. insulin promotes glycogen formation & glucagon
stimulates glycogen breakdown
Control of Hormone Secretion
• Regulated by signals from nervous system, chemical
changes in the blood or by other hormones
• Negative feedback control (most common)
• decrease/increase in blood level is reversed
• Positive feedback control
• the change produced by the hormone causes more
hormone to be released
• Disorders involve either hyposecretion or
hypersecretion of a hormone
Endocrine Gland Stimuli
How are endocrine glands stimulated?
1. Hormonal - where a hormone stimulates the gland to
release its hormone
•
tropic hormone - a hormone that stimulates a gland
to release another hormone
•
-tropin a suffix often used on tropic hormones
2. Humoral - where the gland monitors the conditions it is
going to control
3. Neural - where a nerve impulse stimulates the gland to
release its hormone
Hypothalamus & Pituitary Gland
Hypothalamus
Oxytocin
Antidiuretic hormone (ADH)
Releasing hormones
Inhibiting hormones
Anterior Pituitary
Growth hormone (GH)
Thyroid stimulating hormone (TSH)
Follicle-stimulating hormone (FSH)
Luteinizing hormone (LH)
Prolactin (PRL)
Adrenocorticotropin hormone (ACTH)
Melanocyte-stimulating hormone (MSH)
Anterior Pituitary Hormones
Posterior pituitary
Posterior pituitary
Posterior Pituitary Hormones
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•
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ADH
Oxytocin during Labor
Stimulation of uterus by baby
Hormone release from posterior
pituitary
Uterine smooth muscle
contracts until birth of baby
Baby pushed into cervix,
increase hormone release
More muscle contraction occurs
When baby is born, positive
feedback ceases
Thyroid Gland
Actions of Thyroid Hormones
Control of
T3 & T 4
Secretion
Parathyroid Gland
Regulation of Calcium Blood Levels
Actions of Parathyroid Hormones
Adrenal Gland
Adrenal Gland
Cortex
Medulla
•
• receive innervation from
sympathetic nervous system
mineralocorticoids
• Aldosterone
• increase reabsorption of Na+
with Cl- (and H2O)
• promotes excretion of K+ and
H+
• glucocorticoids
• cortisol
• corticosterone
• cortisone
• androgens
• dehydroepiandrosterone (DHEA)
• release epinephrine and
norepinephrine in response to
stress
• Produces rapid, drastic effects
involving several targets (fight
or flight response).
Regulation of Aldosterone
Glucocorticoids
Cortisol
• 95% of glucocorticoid
activity
• protein catabolism
• glucose formation
• stimulate lipolysis
• resistance to stress
• anti-inflammatory effects
• depression of immune
responses
Summary of Adrenal Gland
Hormones
Stress Response
Pancreas
Functions of Pancreas
Exocrine function
- Acini - cells clusters that produce digestive enzymes
Endocrine function
- Islets of Langerhans
- clusters of hormone secreting cells
Regulation of
Glucagon &
Insulin
Secretion
Pancreatic Islet Hormones
Pineal Gland
Other Hormones
Pituitary Gland Disorders
Pituitary dwarfism
- hyposecretion of hGH
Giantism
- hypersecretion of hGH (childhood)
Acromegaly
- hypersecretion of hGH (adult)
Thyroid Gland Disorders
Congenital hypothyroidism
- hyposecretion of thyroid hormone
Myxedema
- hypothyroidism during adult years
Grave’s disease
- hyperthyroidism
- exophthalmos (edema behind eyes)
Goiter
- enlarged thyroid
Thyroid Hormone Disorders
Hyperthyroidism - excessive secretion high
basal metabolism (Grave’s disease), high
temperature, sweating, weight loss, irritability,
high bp
Hypothyroidism - deficiency (cretinism)
weight gain, lethargy, intolerance to cold,
simple goiter
Adrenal Gland Disorders
Cushing’s Syndrome
- hypersecretion of cortisol
Addison’s Disease
- hyposecretion of glucocorticoids and
aldosterone
Diabetes Mellitus & Hyperinsulinism
Type I
- insulin-dependent diabetes mellitus (IDDM)
Type II
- non-insulin-dependent diabetes mellitus (NIDDM)