Download endocrine system

Hypothalamus and
Pituitary Function
Chemistry CLS415 Didactics
Module 1
Introduction to Endocrinology:
Basic Concepts
Objectives:
 Define the following terms:
– Hormone
– Target organ
– Endocrine system
– Exocrine system
– Receptors
 List the major endocrine glands and the hormones
they secrete
 Describe the action of hormones in terms of their:
– Regulatory and physiologic functions
– Morphologic action
– Integrative action
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What is Endocrinology?
Study of intracellular and
extracellular communication by
hormones of the endocrine system
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Transmission of Information
 Occurs through several
systems or networks
–
–
–
–
Nervous System
Immune System
Hormonal System
Others
 Endocrine system is
controlled by its linkage
with CNS through
hypothalamus and
pituitary glands
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The Endocrine System
 A ‘fine-tuned’ communication system

Maintains cellular homeostasis
– Body metabolism
– Growth and development
– Reproduction
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Major Endocrine Glands
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Hypothalamus
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What are Hormones?
 Chemical messengers
– Interact with target organs by specific receptors
– Illicit biologic response
 Different modes of transport and action
 Example:
Endocrine
Exocrine
Juxtacrine
Neurocrine
Paracrine
Autocrine
Neuroendocrine
Neurotransmission
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Endocrine vs Exocrine
Pancreas: insulin
Pancreas: amylase & lipase
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Hypothalamus
 Releasing Hormones (factors)
 Inhibiting Hormones (factors)
Act on
anterior
pituitary
gland
 Produce ADH and Oxytocin
Stored in posterior pituitary gland
Release
Tropic
Hormones
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Stimulating (tropic) Hormones
Stimulating = tropin = trophic = tropic
Stimulating hormones are specific to
a particular target organ or target cell
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Stimulating (tropic) Hormones
Gonadotropin: stimulates the gonads
Target gland = testes and ovaries
Thyrotropin: stimulates the thyroid
Target gland = thyroid gland
ACTH = adrenocorticotropic hormone:
stimulates the adrenal gland
Target gland = adrenal cortex
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Stimulating (tropic) Hormones
 Stimulating hormones interact with their
target glands through receptors
 Membrane receptors:
– Located on the cell membrane
– Interact with protein-type hormones
 Cytoplasmic receptors:
– Located in the cytoplasm of the cell
– Interact with steroid-type hormones
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Table, page 2 of handout
Endo
Gland
Anterior
Pituitary
Hormone
from endocrine gland
Site of hormone’s
action (target)
Biological
response of
target
TSH
Thyroid gland
Form T3,T4
ACTH
Adrenal cortex
Form Steroid
FSH, LH
tropic
Ovary, testis
hormones
Sexual
maturation
GH
Body as a whole
Bone/muscle
MSH
Skin
Darken skin
Prolactin
Mammary glands
Lactation
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Pituitary Gland (hypophysis)
Posterior
pituitary
Anterior
pituitary
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Table, page 2 of handout
Endo
Gland
Hormone from
endocrine gland
Posterior ADH
Pituitary
Oxytocin
Site of hormone’s
action (target)
Biological response
of target
Renal tubules,
arterioles
Reabsorb H2O
 BP
Uterus,
Breast tissue
Contraction
Milk ejection
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Table, page 2 of handout
Site of hormone’s
action (target)
Endo
Gland
Hormone from
endocrine gland
Biological response of
target
Thyroid
T3 and T4
General body tissue
 O2 consumption,
 BMR
Calcitonin
Bone
Inhibits calcium
resorption (keeps
calcium in bone)
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Table, page 2 of handout
Endo
Gland
Adrenal
Cortex
Site of hormone’s
action (target)
Biological response
of target
Cortisol
General body
tissue
Carbohydrate,
protein, fat
metabolism
Aldosterone
Kidney tubules
(DCT, collecting)
Salt and water
balance
Hormone from
endocrine gland
Steroid hormones:
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Table, page 2 of handout
Endo
Gland
Adrenal
Medulla
Hormone from
endocrine gland
Site of hormone’s
action (target)
Biological response
of target
Norepinephrine and
Epinephrine
Sympathetic
receptors
Stimulate
sympathetic
nervous system
Epinephrine =
‘Fight or Flight’
hormone
Liver, muscle, fat
Glycogenolysis,
lipolysis
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Regulatory and Physiologic
Functions
 Electrolyte and water balance
– Aldosterone: Na+ (and K+, H+)
– ADH: water reabsorption
 Storage and use of nutrients
– Insulin: carbohydrate (glucose) regulation
– Cortisol: carbohydrate, protein, lipid
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Morphogenic Action
 Synthesis of cellular compounds
– Thyroid hormone
– Catecholamines
– Steroid hormones
 Growth and development
– GH (growth hormone)
– Thyroid hormones
– Steroid hormones
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Morphogenic Action
 Sexual maturation and reproduction
– Gonadotropins (LH and FSH)
– Estrogen (female sex hormone)
– Testosterone (male sex hormone)
– HCG (human chorionic
gonadotropin)
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Integrative Action
No hormone works alone!
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Integrative Action
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