endocrine system nestor t. hilvano, m.d., m.p.h. (images copyright discover biology, 5 th ed.,...
TRANSCRIPT
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 1. 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
Hypothalamus • Master control center• Signals pituitary gland, which in turn secretes
hormones that influence many body functions• Secretes releasing and inhibitory hormones
Brain
Posterior pituitary
Anterior pituitary
Bone
Hypothalamus
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 ADH- increase
reabsorption of water in kidney tubules (DCT/ CT)
• Effect of oxytocin- uterine contraction; milk ejection
Hypothalamus
Neurosecretorycell
Hormone
Posteriorpituitary
Bloodvessel
Oxytocin ADH
Uterine musclesMammary glands
Kidney tubules
Anteriorpituitary
Pituitary Gland1. 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)
Neurosecretorycell
Bloodvessel
Releasing hormonesfrom hypothalamus
Pituitary hormones
TSH ACTH FSHandLH
Growthhormone
(GH)
Prolactin(PRL)
Endorphins
Thyroid Adrenalcortex
Testes orovaries
Entirebody
Mammaryglands
(in mammals)
Painreceptors
in the brain
Endocrine cells ofthe anterior pituitary
Figure 26.4E
Hypothalamus
Anteriorpituitary
Thyroid
Thyroxine
Inhibition
Inhibition
TRH
TSH
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 deficiencya. 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.