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Hypothalamus and Pituitary
FunctionChemistry CLS415
Didactics
Module 1Introduction to
Endocrinology: Basic Concepts
2
Objectives: Define the following terms:
– Hormone– Target organ– Endocrine system
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
– Exocrine system– Receptors
3
What is Endocrinology?
Study of intracellular andextracellular communication byhormones of the endocrine
system
4
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
5
The Endocrine System
A ‘fine-tuned’ communication system
Maintains cellular homeostasis– Body metabolism– Growth and development– Reproduction
8
What are Hormones? Chemical messengers
– Interact with target organs by specific receptors
– Illicit biologic response Different modes of transport and action Example:
Endocrine ParacrineExocrine AutocrineJuxtacrine NeuroendocrineNeurocrine Neurotransmission
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Hypothalamus Releasing Hormones (factors) Inhibiting Hormones (factors)
Produce ADH and Oxytocin
Stored in posterior pituitary gland
Act on anterior pituitary gland
Release Tropic Hormones
11
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 gonadsTarget gland = testes and ovaries
Thyrotropin: stimulates the thyroidTarget 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
14
tropic hormones
Table, page 2 of handoutEndo Gland
Hormonefrom endocrine gland
Site of hormone’s action (target)
Biological response of target
Anterior Pituitary
TSH
ACTH
FSH, LH
GH
MSH
Prolactin
Thyroid gland
Adrenal cortex
Ovary, testis
Body as a whole
Skin
Mammary glands
Form T3,T4
Form Steroid
Sexual maturation
Bone/muscle
Darken skin
Lactation
16
Table, page 2 of handout
Endo Gland
Hormone from endocrine gland
Site of hormone’s action (target)
Biological response of target
Posterior Pituitary
ADH
Oxytocin
Renal tubules, arterioles
Uterus, Breast tissue
Reabsorb H2O BP
ContractionMilk ejection
17
Table, page 2 of handout
Endo Gland
Hormone from endocrine gland
Site of hormone’s action (target)
Biological response of target
Thyroid T3 and T4
Calcitonin
General body tissue
Bone
O2 consumption, BMR
Inhibits calcium resorption (keeps calcium in bone)
18
Table, page 2 of handout
Endo Gland
Hormone from endocrine gland
Site of hormone’s action (target)
Biological response of target
Adrenal
Cortex Steroid hormones:
Cortisol
Aldosterone
General body tissue
Kidney tubules
(DCT, collecting)
Carbohydrate, protein, fat metabolism
Salt and water
balance
19
Table, page 2 of handoutEndo Gland
Hormone from endocrine gland
Site of hormone’s action (target)
Biological response of target
Adrenal
Medulla Norepinephrine and Epinephrine
Epinephrine =‘Fight or Flight’ hormone
Sympathetic receptors
Liver, muscle, fat
Stimulate sympathetic nervous system
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
22
Morphogenic Action Sexual maturation and
reproduction– Gonadotropins (LH and FSH)– Estrogen (female sex hormone)– Testosterone (male sex hormone)– HCG (human chorionic
gonadotropin)