Download Hormones of the Body

Hormones of the Body
We’ll go through all the glands
and the hormones they produce in
this PowerPoint Presentation!
By Dawn Tamarkin, Ph.D.
Springfield Technical Community College
The Hypothalamus & the Pituitary
Gland-- Master Endocrine Glands!
The Hypothalamus:
• Located in the brain,
this region controls
most endocrine
secretions
• Mainly regulatory
hormones are released
here. Most control the
pituitary gland
The Pituitary Gland
• Descending from the
hypothalamus, this gland
has two halves: anterior &
posterior
• The anterior half secretes
mainly regulatory
hormones
• The posterior half secretes
hormones, but
manufactures none
Hormones secreted by the Hypothalamus
& Anterior Pituitary Gland
Hypothalamus
GHRH (GH-releasing)
SS (somatostatin, GH-inhib)
CRH (corticotropin-rel)
GnRH (gonadotropin-rel)
“
PRH (PRL-releasing)
PIH (PRL rel-inhibiting)
TRH (thyrotropin-rel)
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Anterior Pituitary
GH (growth hormone)
“
ACTH (adrenocorticotropic)
LH (luteinizing hormone)
FSH (follicle-stimulating)
PRL (prolactin)
“
TSH (thyroid stimulating)
What do these anterior pituitary
hormones do?
Growth Hormone:
• stimulates cells to grow
and divide
• increases amino acid
transport rate and protein
synthesis
• increases fat metabolism
Typically, GH is secreted
during sleep.
GH secretion increases when
malnourished
GH influences bone
growth via
somatomedin:
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GH in blood
GH arrives in liver
liver secretes somatomedin
cartilage divides
bones grow!
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Problems with GH
• Too much GH in children leads to gigantism
• Too much GH in adults leads to acromegaly
• Too little GH in children leads to dwarfism
Other Anterior Pituitary Hormone
Functions
ACTH:
LH & FSH:
• works on the cortex of the
adrenal gland, influencing
the release of cortisol
• stress can increase CRH
secretion which will
increase ACTH secretion
• negative feedback when
adrenal cortex hormones
in blood decrease CRH
secretion
• LH in females and in males leads
to sex hormone secretion
• FSH in females causes growth
and development of egg cellcontaining follicles in the ovary,
and causes estrogen secretion
• FSH in males instigates sperm
production
• both hormones are regulated by
GnRH, which is not significant in
concentration until puberty
More Anterior Pituitary Hormone
Functions
PRL:
TSH:
• In females, PRL promotes
lactation
• In males, PRL decreases
LH secretion (note that
too much PRL would then
decrease androgen levels
and cause sterility)
• Controlled by both PRH
and PIH
• works on thyroid gland to
either cause or inhibit its
secretion of hormones
• works on thyroid gland to
affect its growth (too much
TSH leads to a goiter)
• negative feedback via thyroid
hormones in blood
• stress or cold temperatures
can change TSH secretion
The Posterior Pituitary Lobe
No hormones are made here. They are made
in the hypothalamus and just released here.
Two peptide hormones are released from the
posterior pituitary lobe (the neurohypophysis):
• ADH (antidiuretic hormone or vasopressin)
• OT (oxytocin)
Function of Posterior Pituitary
Lobe Hormones
ADH:
OT:
• as an “antidiuretic,” ADH
decreases urine formation by
having kidneys conserve water
• also can contract smooth muscle
cells, as found in blood vessels-this causes an increase in blood
pressure
• ADH release triggered by
osmoreceptors and inhibited by
stretch receptors in blood vessels
• In females, contracts the
uterine wall smooth
muscles
• In females, helps to eject
milk when lactating
• No known function in
males, although in both
males and females, OT
can have some antidiuretic
effects
The Thyroid Gland
Structure:
This bilobed gland contains many follicles. A follicle
is a group of cells encircling a lumen. The lumen contains material
called colloid (a glycoprotein) within it. As hormones are
produced by the cells, the hormones are either released into the
colloid or directly into the blood.
There are also extrafollicular hormone-secreting cells, called
C cells. These are found between lumina.
Hormones Produced:
• Thyroxine (T4)
• Triiodotyronine (T3)
• Calcitonin
made in follicle
made in follicle
made by C cells
About the Thyroid Hormones...
T3 and T4:
Calcitonin:
• Function: metabolism regulation • Function: decrease blood
(break down carbohydrates and
calcium levels and blood
fats, synthesize proteins)
phosphate levels (by
helping them get
• Can only be made by follicular
deposited in bone, and by
cells when iodides are available
stimulating excretion of
• Somewhat hydrophobic and get
them by kidneys)
carried by proteins in the blood.
• Controlled by blood
• Controlled by anterior pituitary
calcium levels and
lobe TSH
digestive chemicals
• T3 more effective, T4 more
abundant
Problems with the Thyroid Gland
Hyperthyroidism:
• high metabolic rate, hyperactivity, sensitivity to heat, protruding eyes
• Grave’s disease: when hyperthyroidism is due to an autoimmune
problem (TSH is mimicked by autoantibodies)
Hypothyroidism:
• in the adult: low metabolic rate, sensitivity to cold, sluggishness
• in an infant: cretinism-- stunted growth, mental retardation,
abnormal bone formation
• Hashimoto’s disease: when hypothyroidism is due to an
autoimmune problem (autoantibodies attack and destroy follicular
cells)
• goiter: no T3 and T4 can be made because not enough iodides were
ingested.
Let’s Review:
What glands and hormones did we
learn about so far?
Hypothalamus & Anterior Pituitary
Hypothalamus
GHRH (GH-releasing)
SS (somatostatin, GH-inhib)
CRH (corticotropin-rel)
GnRH (gonadotropin-rel)
“
PRH (PRL-releasing)
PIH (PRL rel-inhibiting)
TRH (thyrotropin-rel)
Anterior Pituitary
GH (growth hormone)
“
ACTH (adrenocorticotropic)
LH (luteinizing hormone)
FSH (follicle-stimulating)
PRL (prolactin)
“
TSH (thyroid stimulating)
Your book’s review diagram:
Posterior Pituitary & Thyroid Gland
Posterior Pituitary:
• ADH
• OT
Both of these hormones are
made in the
hypothalamus… their
release is regulated by the
brain.
Thyroid Gland:
• T3 (regulated by TSH)
• T4 (regulated by TSH)
• calcitonin (NOT
regulated by the
pituitary!)
Moving on to More Glands!
We still have the following left:
•
•
•
•
•
Parathyroid Gland
Adrenal Gland: both the Medulla and the Cortex
Pancreas
Pineal
Other, including thymus and reproductive glands
Parathyroid Gland
• This gland only
secretes one
hormone:
Parathyroid
Hormone (or PTH)
• PTH function (we
began learning this when
we studied bone):
– increases blood
calcium (Ca2+)
levels and
decreases blood
phosphate (PO42-)
levels
PTH function (continued)
• How does PTH work?
– PTH causes Ca2+ & PO42- to be released from bone into
blood (by increasing osteoclast activity)
– PTH causes the kidneys to remove PO42- ions from the
urine
– PTH increases vitamin D production, so that you absorb
more Ca2+ during digestion
• PTH is regulated by blood calcium levels-- not by
other glands!
Adrenal Glands
An adrenal gland is found on top of each kidney.
Each adrenal gland has two regions that carry out
separate functions!
•The adrenal medulla
•The adrenal cortex
We will cover each of
these two regions
separately in the next few
slides.
The Adrenal Medulla
Acts very much like a part of the sympathetic
nervous system (fight or flight)
Secretes two amines:
– norepinephrine (20%)
– epinephrine (80%)
Stimulated by preganglionic neurons directly, so
controlled by the hypothalamus as if part of the
autonomic nervous system, NOT by tropic
hormones
The Adrenal Cortex
Acts like a regular endocrine organ
Secretes many hormones, but most importantly
secretes the following steroids:
– aldosterone
– cortisol
– sex hormones
Aldosterone and cortisol require further explanation
(while sex hormone production will be covered later this
semester)
More about Adrenal Cortex Hormones
Aldosterone:
Cortisol:
Considered a mineralocorticoid
Considered a glucocorticoid
Regulates “mineral electrolyte” levels in
the blood (for example: Na+ and K+
ions)
How is aldosterone controlled?
– blood plasma ion concentrations
affect its secretion directly (but
not always strongly)
– kidney secretes renin in response
to altered electrolyte levels,
which triggers angiotensin
activation in the blood, which
leads to aldosterone secretion
– ACTH from the anterior pituitary
can cause aldosterone secretion
Overall effect of cortisol:
• Helps to keep blood glucose
concentration within a normal range
between meals
Specific actions of cortisol:
• increases amino acid concentration
in the blood (by inhibiting protein
synthesis in select tissues)
• promotes use of fat for energy
production in our bodies (rather than
glucose)
• stimulates the liver to synthesize
glucose (not from carbohydrates, but
from amino acids and glycerol),
called gluconeogenesis
The Pancreas
• This gland has both endocrine and exocrine
functions… we’ll only cover the endocrine portion now
(exocrine is for digestion)
• The endocrine portion of the gland contains three types
of cells, each making a different hormone, arranged
into groups called Islets of Langerhans
– alpha cells: secrete glucagon
– beta cells: secrete insulin
– delta cells: secrete SS (somatostatin)
• Note that these pancreatic hormones are involved in
blood glucose regulation, and problems with them can
lead to diabetes.
Blood Glucose Regulation by the Pancreas
Glucagon:
It works on the liver to cause
the production of glucose
via:
– glycogenolysis
– gluconeogenesis
It is regulated by blood
glucose levels directly:
Insulin:
It works on the liver to
remove glucose from the
blood via:
– making glycogen
– preventing gluconeogenesis
– increasing glucose transport
into cells
– secreted when blood glucose It is also regulated by blood
glucose levels directly
drops (before next meal)
Prevents hypoglycemia
Prevents hyperglycemia
Note: glucagon and insulin work in opposition, and
their combined effects control blood glucose
Pineal Gland
Secretes only one hormone: melatonin
Involved in your circadian rhythm (your
recognition of day and night times):
– melatonin secretion decreases in the day
– melatonin secretion increases at night
Melatonin is also involved in longer rhythms,
like monthly and seasonal… and is thought to
be involved in the female menstrual cycle and
maybe in the onset of puberty
Other Endocrine Glands
• Thymus Gland: secretes thymosins which
are involved in white blood cell production
• Reproductive glands (the gonads): the
ovaries and the testes produce sex hormones
• Others: too specific for now, we’ll get to
them as we continue this semester.