Download Endocrine System

Endocrine System
Nestor T. Hilvano, M.D., M.P.H.
(Images Copyright Discover Biology, 5th ed., Singh-Cundy and Cain,
Textbook, 2012.)
Learning Objectives
1. Describe the 3 types of hormones by chemical
structure.
2. Describe the endocrine system as to types and
functions of endocrine organs including its
regulatory control.
- pituitary gland, pineal gland, thyroid and
parathyroid glands, pancreas, adrenal glands, and
gonads.
4. Define hypothyroidism, hyperthyroidism, goiter,
diabetes mellitus, and hypoglycemia.
5. Describe the benefits and risks of using
glucocorticoids.
Endocrine System
• Ductless glands
• Hormones – chemical signals secreted and pass directly
into the blood circulation to reach the target organs
3 Types of Hormones
Proteins and peptides – most numerous group; H2O
soluble; ex. TSH, LH, FSH, ADH, prolactin
2. Amine – derivatives of tyrosine; some H2O soluble,
some lipid soluble; ex. TH, Epi, Nor-Epi, dopamine
3. Steroids – not H2O soluble ex. sex hormones
Mechanisms of Action on target cells:
1. Lipid soluble hormones – bind to cytoplasm or nuclear
receptors (inside the cell)
2. Water soluble hormones – bind to receptor on plasma
(cell) membrane; w/ second messenger
1.
Hypothalamus
• Master control center
• Signals pituitary gland, which in turn secretes
hormones that influence many body functions
• Secretes releasing and inhibitory hormones
Brain
Hypothalamus
Posterior pituitary
Anterior pituitary
Bone
Hypothalamus: The Master Gland
Figure 18–9 Pituitary Hormones and Their Targets.
Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Pituitary Gland
• Posterior pituitary –
stores and secretes
hormones made in
the hypothalamus
- ADH, and oxytocin
• Effect of ADHincrease reabsorption of
water in kidney tubules
(DCT/ CT)
• Effect of oxytocinuterine contraction; milk
ejection
Hypothalamus
Hormone
Neurosecretory
cell
Posterior
pituitary
Anterior
pituitary
Blood
vessel
Oxytocin
ADH
Uterine muscles
Mammary glands
Kidney tubules
Pituitary Gland
1. Tropic hormones (control
other glands)
• TSH (thyroid stimulating hormone)
• ACTH (adrenocorticotropic
hormone)
• LH and FSH (luteinizing hormone
and follicular stimulating hormone)
2. GH (growth hormone)
3. Prolactin (lactogenic hormone)
4. Endorphins (pain receptors in
brain)
5. MSH (melanocytes stimulating
hormone)
Neurosecretory
cell
Blood
vessel
Releasing hormones
from hypothalamus
Endocrine cells of
the anterior pituitary
Pituitary hormones
TSH
ACTH
FSH
and
LH
Growth
hormone
(GH)
Thyroid
Adrenal
cortex
Testes or
ovaries
Entire
body
Prolactin
(PRL)
Endorphins
Mammary
Pain
glands
receptors
(in mammals) in the brain
Figure 26.4E
Hypothalamus
Inhibition
TRH
Anterior
pituitary
TSH
Thyroid
Thyroxine
Inhibition
Pineal Gland
• Brain outgrowth
• Secretes melatonin,
with rhythmical
activity and biologic
clock functions
• SAD syndrome
Thyroid Gland
• Located beneath the larynx
• Secretions: Thyroid Hormones
(T3, T4); increase BMR
• Cretinism – congenital
deficiency of thyroxine in
children resulting to physical
and mental retardation
• ___ – increase TH
• ___ – decrease TH
• ___ – enlarged gland; caused
by iodine deficiency
a. Hypothyroidism
b. Goiter
c. Hyperthyroidism
Calcium Homeostasis
• Calcium level in the blood and
interstitial fluids are essential
• Maintained by calcitonin (to
decrease calcium) from thyroid gland
and PTH (parathyroid hormone, to
increase calcium) from the
parathyroid glands
• PTH- increase blood calcium level
by: increase bone destruction,
increase calcium reabsorption in
kidneys, and increase calcium
absorption in GIT
Pancreatic Hormones
• Regulate blood glucose levels
• Islets of Langerhans – endocrine part
- Insulin is a protein hormone produced
by beta cells; lower BS
- Glucagon is a peptide hormone
produced by alpha cells; increase BS
• Diabetes Mellitus:
Type I = destruction of beta cells; no
insulin produced
Type II = low or not responsive to
insulin (insulin resistance)
*DM= hyperglycemia, glycosuria (polydipsia, polyuria,
polyphagia)
• Hypoglycemia – secrete too much insulin,
lower the blood sugar
Adrenal Gland
• Adrenal cortex – produces hormones that provide
slower, longer term responses to stress; secretes steroid
hormones – mineralocorticoids (aldosterone),
glucocorticoids, and androgens
* Glucocorticoids offer relief of pain; suppress body’s defense system
• Adrenal medulla – ensures a rapid, short term response
to stress; releases epinephrine and norepinephrine.
* Secretions stimulate liver and muscle cells to release glucose for energy use
Gonads
• Male = testes; testosterone
• Female = ovaries; estrogen; progesterone
• Sex hormones
1. affect growth and development
2. regulate reproductive cycles and sexual
behavior.
Homework
1. Define terms: endocrine gland, hormones,
goiter, hyperthyroidism, hyperglycemia,
hypoglycemia, and hypothyroidism.
2. Discuss the hormonal effects in regulation of
blood calcium level and regulation of blood
glucose level.
3. List the hormones secreted and its functions
(effects) of the following endocrine organs:
thyroid, posterior pituitary, anterior pituitary,
adrenal gland, pineal gland, pancreas, testes,
and ovaries.