Download Endocrine System

Endocrine System
Learning objectives
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What is a hormone? How and where do hormones send messages?
What is the difference between ‘steroid hormones’ and ‘nonsteroid hormones’?
How does the hypothalamus connect the nervous system with the endocrine
system?
For each of the following hormones, you should know in what gland they are
produced, and what their general effects are:
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Growth hormone
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Thyroid hormone
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Calcitonin
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Parathyroid hormone
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Epinephrine (adrenaline)
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Insulin
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Glucagon
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Androgens and Estrogens (general development of secondary sexual
characteristics)
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Melatonin
What are Type 1 and Type II Diabetes?
Hormones and Target Cells
1. Endocrine cells
release hormone.
2. Hormone enters
circulation.
3. Hormone is
carried throughout the body.
Hormone will not
bind to cells that
are not target cells
4. Binding occurs;
receptor
target cell
(skeletal muscle)
hormonal effects
take place.
Hypothalamus and Pituitary
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Hypothalamus
connects nervous
system with
endocrine system
Hypothalamus
‘controls’ pituitary
gland
(a) Hypothalamus
hypothalamus
anterior
pituitary
posterior
pituitary
(b) Two means of endocrine control by the hypothalamus
Pituitary is
divided into
Anterior and
Posterior
which work in
quite different
ways
1. Hypothalamic neurons
secrete hormones into
upper capillary bed.
2. These hormones
travel down connecting
blood vessels . . .
1. Hypothalamic neurons
synthesize hormones
that travel down axons.
3. . . . and diffuse out
of lower capillary
bed into anterior
cells . . .
4. . . . controlling the
release of anterior
pituitary hormones
into general circulation.
2. These are released
into capillary bed . . .
anterior
pituitary
posterior
pituitary
3. . . . and then move from
it into general circulation.
hypothalamus
vasopressin
Controls retention
of water in the body
by the kidneys
kidneys
anterior
pituitary
prostate gland
in males
oxytocin
Stimulates contraction of
uterus muscles and release
of milk in females; assists in
semen ejaculation in males
posterior
pituitary
uterus and mammary
glands in females
medulla
cortex
adrenocorticotropic
hormone (ACTH)
Stimulates adrenal cortex
to secrete glucocorticoids,
which regulate energy use
thyroid-stimulating
hormone (TSH)
Triggers release of thyroid
hormones, which increase
metabolic rate
growth hormones (GH)
Stimulates growth by
prompting liver’s release of
somatomedin hormones
adrenaline + noradrenaline
adrenal gland
glucocorticoids
T3, T4 hormones
thyroid gland
bone, muscle,
other tissues
prolactin (PRL)
Stimulates mammary
gland development and
production of milk
mammary glands
follicle-stimulating
hormone (FSH)
Male: promotes
sperm production
Female: promotes egg
development; stimulates
ovaries to produce estrogen
luteinizing
hormone (LH)
Female: produces ovulation;
stimulates ovaries to produce
estrogen and progesterone
Male: stimulates testes to
produce androgens
testosterone
testes
estrogen
progesterone
ovaries
Hormone
levels are
often
regulated by
negative
feedback
loops
T3 and T4 suppress
production of TRH
hypothalamus releases
thyrotropin-releasing
hormone (TRH)
T3 and T4 suppress
production of TSH
anterior pituitary releases
thyroid-stimulating
hormone (TSH)
metabolic
rate of cells
increases
throughout
body
thyroid gland
releases T3 and T4
Growth hormone (HGH)
Growth hormone
Thyroid
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Thyroid hormone
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Growth
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Metabolism
Calcitonin
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Regulates calcium use
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Promotes bone growth
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Reduces calcium in blood
Parathyroid gland
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Opposite effects of
Calcitonin
Parathyroid hormone
Adrenal Glands
Two parts:
Adrenal Cortex
Adrenal Medulla
Adrenal medulla
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Releases epinephrine
(adrenaline) and
norepinephrine
(noradrenaline) which
triggers ‘fight or flight’
response
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Stimulated by
sympathetic division of
autonomic nervous
system
Adrenal cortex
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Responds to signals
from hypothalamus,
instead of nervous
system
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Aids in metabolism of
glucose and in
maintaining salt and
water balance
Pancreas
Release insulin
and glucagon
into blood
Glucose regulation
• Hypoglycemia
• Too
little sugar in blood
• fasting
• too
much insulin
• Hyperglycemia
• Too
much sugar in blood
• Insulin
may not be present or is ineffective
Type 1 Diabetes
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Reduced insulin production (if any)
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Perpetually hyperglycemic
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Sugar is in blood but cannot be used by cells
Managed by insulin replacement
Type 2 Diabetes
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Body becomes ‘immune’ to insulin
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Insulin is ineffective
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Perpetually high blood sugar levels
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Effects of hyperglycemia
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Body burns fats instead of glucose
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Waste product of fat metabolism (ketones) is toxic
Diabetes best managed by diet and exercise