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Endocrine System
Some Review First
4 types of cell signal mechamisms
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Direct Contact- see table and page
127
Paracrine Signaling, message
transmitted to neighboring cells
Synaptic signaling —
neurotransmitters carry messages
between nerve cells
*Endocrine signaling —hormones
travel through circ system
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Focus of this presentation
Hormones-4 groups
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Polypeptides-short chains of aa’sinsulin and ADH (anti-diuretic
hormone)
Glycoproteins-longer chains of aa’FSH and LH (from reproductive
system)
Amines-from tyrosine and
tryptophan-melanin and epinephrine
Steroids- derived from cholesterol
(inc. ring shape)-testosterone and
progesterone
2 Hormone Mechanisms
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Lipid or steroid hormones—diffuse
into cell and trigger response
Protein or peptide hormones– use a
second messenger system
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Hormone binds (1st messenger)
Triggers intracellular response via a G
protein  c AMP (second messenger)
ANTERIOR PITUITARY
HORMONES
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Growth Hormone (GH) – Stimulates bone
growth
Luteinizing Hormone (LH) – Stimulates
ovaries and testes
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Follicle Stimulating Hormone(FSH)stimulates gonads to produce sperm and
ova
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Named for corpus luteum
Named for follicle
Thyroid Stimulating Hormone (TSH)Stimulates thyroid gland
Gigantism
Posterior Pituitary Hormones
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Oxytocin – Stimulates contractions
of uterus and mammary glands,
associated with love and bonding.
Antidiuretic hormone (ADH) –
retention of water by kidneys
GONADS AS GLANDS
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Ovaries
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Estrogen – stimulates uterine lining,
development of primary and secondary
female characteristics
Progesterone – Uterine lining growth,
helps maintain pregnancy
Testes
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Androgens (testosterone) – sperm
production (after stimulation by FSH),
secondary sex characteristics
Thyroid
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Thyroxine– controls metabolic rate
Calcitonin– lowers blood calcium
levels (deposits Ca++ in bone)
Hypothyroidism may lead to goiter
 Hyperthyroidism may lead to protrusion of
the eyes (bulging) and Grave’s Disease
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Both problems make it difficult to control
metabolic rate
Cretinism
Hyposecretion of thyroxine in childhood
Parathyroid
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Parathyroid Hormone (PTH) Raises
blood calcium level (removes Ca ++
from bone)
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Hypoparathyroidism - Bones become
weakened
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Osteoporosis—same outcome, but for a
variety of reasons
Osteoporosis
PANCREASIslets of Langerhans
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Insulin – β cells – lowers blood
glucose levels
Glucagon – α cells -raises blood
glucose levels
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Read Analyzing Functions of Pancreas
(Dog Studies)
Diabetes
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Type 1 – Hyposecretion of Insulin,
Insulin Dependent diabetes
Type 2 – Cellular response to insulin
is decreased
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Associated with obesity, strong diet
correlation
Diabetes
Uncontrolled diabetes can lead to damage of many
systems. Some problems may be kidney disease,
nervous system problems, blindness, peripheral
vascular disease.
Adrenal Glands
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Adrenal Medulla – Catecholamines Epinephrine
and Norepinephrine raises blood sugar by incr.
breakdown of glycogen in liver, short term stress
response
Adrenal Cortex --Glucocorticoids -- raise blood
sugar levels, long term stress response
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Overproduction—Cushing’s Disease (breakdown of
proteins and unusual fat distribution)
Long term stress has adverse effects on many
systems
THYMUS
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Thymosin– Stimulates T
lymphocytes
Pineal
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Melatonin - Biorhythms –Day and
Night Cycles
Homeostasis
 Homeostasis
may be
thought of as a see-saw
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(Look at anatomy transparency 14.20)
Negative feedback--Return to
baseline- balance see-saw
Positive feedback--Continued
unbalance
ANTAGONISTS
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Antagonistic hormones have
opposite effects. They work
together to maintain homeostasis.
Ex: Insulin and Glucagon,
PTH and Calcitonin
GLAND INTERACTIONS
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Glands may stimulate (or inhibit)
other glands
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See Thyroxine secretion page 1004
See testes and anterior pituitary page
1071
CASE STUDIES
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See page 102 in ABLE