Physiology 2130 Lecture Notes - Lecture 55: Amplitude Modulation, Endocrine System, Remote Control
1 May 2018
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Lecture 055: Introduction to the endocrine system
Definition
● Endocrine System
○ Tissue and cells capable to secreting and responding to hormones
■ A communication system
○ The 2 component communicate via chemical messengers called hormones
● Neural System
○ Function mediated by electrochemical function along nerves
● Hormones
○ Chemical substance
○ Usually formed in one organ and carried in the blood to another organ
○ Have different specificity of effect
■ Alter the functional activity of just one organ (GnRH) or multiple (T3)
○ Regulator of physiology events
■ Influences a physiological response
○ Effect in minute quantity
○ Synthesized by cells/endocrine glands
○ Endocrine hormone
■ Acts on a distal part of the body
■ Remote control
○ Paracrine hormone
■ Acts on a neighbouring cell
■ Neighbourhood watch
○ Autocrine hormone
■ Acts on the same cell it is produced from
■ Self control
Nervous System
Endocrine System
Form of information transfer
Action potentials
Chemicals (hormones)
Speed of information transfer
Fast (fractions of seconds)
Slow (minutes , hours, days)
Mechanism of graduation
(how to increase the
signaling)
Frequency
Amplitude modulation
● Downstream
application
Mechanism to achieve
specificity
“wiring”
Receptors
find more resources at oneclass.com
find more resources at oneclass.com
Hormone Types
● Peptide/Polypeptide
○ WATER SOLUBLE
■ Can dissolve in blood to travel
○ Small monomers
■ TRH
○ Large multimeric proteins
■ TSH, FSH, LH
● Steroid
○ LIPID SOLUBLE
■ Needs a binding/carrier protein to travel in serum
○ Derive from cholesterol metabolism
■ 4 hydrocarbon rings + side chains
○ Testosterone, estrogen, vitamin D
● Amino Acid derivatives
○ LIPID SOLUBLE
■ Also need a carrier protein
○ Large aromatic structure
○ Epinephrine, thyroxine (T4)
Human Endocrine System
● Gut
○ Regulate food intake and digestion
■ CCK, ghrelin, gastrin, secretin, NPY
● Heart
○ Regulate vascular tone and volume
■ ANP
● Kidney
○ EPO (increases erythrocyte formation)
● Liver
○ Angiotensin
○ IGF-I
○ Thromboprotein (increase platelets)
● Fat
○ Adipokines (leptin)
● Most cells
○ Locally-acting growth factors
○ Cytokines
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Tissue and cells capable to secreting and responding to hormones. The 2 component communicate via chemical messengers called hormones. Function mediated by electrochemical function along nerves. Usually formed in one organ and carried in the blood to another organ. Alter the functional activity of just one organ (gnrh) or multiple (t3) Acts on a distal part of the body. Acts on the same cell it is produced from. Speed of information transfer fast (fractions of seconds) Mechanism of graduation (how to increase the signaling) Needs a binding/carrier protein to travel in serum. Acts on tissue b which causes it to produce hormone b. Increase levels of hormone b tells tissue a to stop production of hormone a. Usually to maintain a physiological set point. During the menstrual cycle the rise in estrogen leads to increase in lh and fsh. Progesterone then downregulates lh and fsh after ovulation. Only certain cells respond to a given hormone.
