Introduction to the endocrine system Ziying WANG Institute
- Slides: 57
Introduction to the endocrine system Ziying WANG Institute of Pharmacology School of Medicine, Shandong University wangziying@sdu. edu. cn
Part 1 Introduction
Endocrinology 1. Definition: the study of hormones and their functions. 2. History: (1) (2) (3) (4) Ancient China 1849, Berthold 1855, Addison’s disease Ernest Starling 1902, Hormone, 1905, “Endocrine system” Ernest Starling (1866 -1927)
Endocrine vs. exocrine
Characteristic of endocrine gland • Without duct • The endocrine cells arranged in cluster, follicle or cords • Rich in capillaries • The secretion is hormone which transported by blood circulation
Endocrine system 1. Endocrine glands (1) Classical endocrine glands (2) Extensive endocrine glands 2. Endocrine cells
Classical endocrine glands
Hormones Definition -- chemical messengers -- secreted by endocrine gland or cells -- released into the blood -- effect on target cells through receptors
Major Hormones
Hormones Functions • to control the regulatory systems in the body (1) homeostasis (2) metabolism (3) growth and development (4) reproduction
Endocrine vs. Nervous regulation Endocrine regulation -broadcasts its hormonal messages to essentially all cells -by secretion into blood and extracellular fluid -requires a receiver to get the message -slow and wider Neural regulation -exerts point-to-point -control through nerves -electrical in nature and fast
Neuroendocrine regulation: 1928, Scharrer
Transportation of Hormones
Endocrine (Telecrine, hemocrine)
Paracrine
Transportation of Hormones
Types of hormones 1. Peptide hormones 2. Steroids 3. Amine hormones (derivatives of the amino acid tyrosine)
Synthesis of hormones Synthesis of peptide hormones Synthesis of steroid hormones Synthesis of amine hormones
The comparison of hormones Receptors Carrier protein Orally active storage Peptides Cell No membrane Not usually Hormone Steroids Cytoplasm Yes /nucleus Yes, mostly Precursor Thyroid hormone nucleus Yes Precursor No Hormone Yes Catecholamines Cell No membrane
The transport of hormones 1. Peptide and CA: water-soluble 2. Steroids and thyroid hormone: bound to proteins Eg. Thyroid hormones binding globulin (THBG) Cortisol binding globulin (CBG) Sex hormones binding globulin (SHBG) Effects of hormone binding proteins: (1) Increase the solubility (2) Create an accessible reserve (3) Increase the biological half time
The metabolism of hormones 1. Peptide hormones: degradation in a lysosome 2. Steroids: excreted in an unchanged form 3. Catecholamines: COMT and MAO 4. Thyroxine: removing the iodine residues Results of metabolism (1) Inactivation (2) Activation
Properties of the hormone effect 1. Specificity 2. Signal transmission 3. High biological efficiency
Properties of the hormone effect 1. Specificity: target, receptor
Properties of the hormone effect 2. Signal transmission
Properties of the hormone effect 3. High Biological Efficiency Low plasma concentration (nmol – pmol/L) →great regulatory function
Part 2 Important concepts in endocrine regulation
Patterns of hormone secretion Different hormones have markedly different patterns of secretion. 1. Set point regulation 2. Episodic secretion 3. Diurnal variation
Regulation of hormone secretion: endocrine axis
Endocrine axis
Regulation of hormone secretion: negative feedback 1. Long-loop feedback: (1) Classical negative feedback (2) Regulated by the end product 2. Short-loop feedback Regulated by the intermediate product 3. Ultrashort-loop feedback
Regulation of hormones secretion
Interaction Between the Hormones • 1. Synergistic effects • 2. Permissive effect • 3. Antagonist effects
Interaction Between the Hormones • 1. Synergistic effects (1) Additive: same effect of the hormones on one target organ (2) Complementary: work on different stages of a physiological procedure
Interaction Between the Hormones • 2. Permissive effect • A hormone enhances the responsiveness of a target organ to the second hormone, and increases the activity of the second hormone.
Interaction Between the Hormones 3. Antagonist effects • One hormone antagonize the effects of another. • Eg. The regulation effect of glucagon and insulin on blood glucose metabolism
Part 3 Endocrine disorders
Endocrine disorders • Normal amount of hormones are essential for the body. • Either excessive or insufficient hormones secretion are disorders. • Excessive secretion: hyper • Insufficient secretion: hypo-
Endocrine disorders Secondary: Hypothalamus or pituitary disorder Primary: endocrine glands disorder
Endocrine disorders
Part 4 Endocrine investigations
General principles 1. Purposes: diagnosis/monitoring 2. After clinical pattern recognition or understanding of physiology and anatomy 3. Blood test maybe basic or dynamic. 1) Basic test : 9: 00 h, fasted 2) Dynamic test: (1) stimulation test : when suspect a hormone is too low. (2) suppression test: when suspect a hormone is too high.
Measurement of hormones 1. Biological sample (1) Blood (2) Urine (3) Biopsy 2. Image: radiological imaging is vital.
Ectopic hormone secretion 1. Definition: The inappropriate secretion of hormones by tissues that do not usually produce that hormones. 2. Clinical significance: as a feature of endocrine tumors. 3. Diagnosis: combined methods.
Receptors and hormone action The first step of a hormone’s action is to bind to specific receptors at the target cell.
Receptors of hormones Protein in nature (may contain carbohydrate or phospholipid moieties) Classification by location: 1. Cell surface receptors 2. Intracellular receptors: 3. (1) cytoplasm receptors 4. (2) nucleus receptors
Receptors of hormones Classification by mechanisms:
Mechanism of hormones action 1. Second messenger mechanisms: 2. Peptide hormones and CA 3. --bind the receptors on the membrane --activate some enzyme on the membrane -- regulate the concentration of second messengers in the cytoplasm
G-protein-coupled Receptor
Second messenger mechanisms
Mechanism of hormones action 2. Gene expression mechanism: Intracellular receptors (1) --bind the receptors in the cytoplasm -- HR complex goes into nuclear Or -- bind the receptors in the nuclear (2) -- bind to target DNA (3) – regulate transcription
Gene expression mechanism
Gene expression mechanism cytoplasm receptors nucleus receptors
Mechanism of hormones action 3. Receptors activate a protein kinase For insulin or growth hormone receptors
- Endocrine system introduction
- Endocrine system and reproductive system
- Endocrine system and nervous system
- Lymphatic system vs endocrine system
- Mechanism of action of hormones
- Endocrine system
- Chapter 16 matching question 6-10
- Parts of the endocrine system
- The body's speedy electrochemical communication network
- Comparison of endocrine and nervous system
- Steroids endocrine system
- Endocrine system fact
- Rat appendix
- Oxication
- Endocrine system pearson
- Exocrine glands are ductless
- Chapter 7 13 endocrine system
- Mammillary body
- Humoral stimulus
- Hypothal
- Biology 30 endocrine system
- Pak pandani
- Chapter 23 the endocrine system
- Endocrine system analogy
- Classification of hormones
- T3.taktak
- Endocrine glands
- Classification of hormone
- Pancreas in endocrine system
- Glands of the endocrine system
- Endocrine system
- Chapter 16 lesson 1 the endocrine system
- Endocrine system regents questions
- Endocrine system regents questions
- Chapter 45 hormones and the endocrine system
- Endocrine tissues
- Chapter 18: the endocrine system answer key
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