Mechanisms of intracellular communication, introduction to the endocrine system.
Function of chemical messengers
To relay information and instructions between cells
Gap junction communication
Communication between adjacent cells through the exchange of ions
Example of direct communication
Gap junction communication-Communication between cells of the same type-Must have extensive physical contact
Details about endocrine system
Contains 30 hormones that regulate= body temperature, sleep, hunger, stress management, growth development and reproduction.
Chemical messengers to relay information and instructions between cells
Chemical messengers that are released in one tissue and transported in bloodstream to alter activities of specific cells in other tissues
Have a known chemical structure
Neighbor signalling Local hormones (Prostaglandins)
Function of gap junctions
-Coordinate ciliary movement among epithelial cells-Coordinate cardiac muscle cell contraction-Facilitate propagation of action potentials
Difference between paracrine and hormones (endocrine)
1. Most cells release paracrine signals/factors
2. Specialized cells release hormones
3. Hormones can stimulate the same cell type or can affect distant cells as well.
What do hormones alter?
They coordinate cellular activities of tissues in distant portions of the body.
Alter operations of genes, existing proteins (and the rate of synthesis of proteins (by changing the rate of transcription and translation)
Turn an existing enzyme or membrane channels "on" or "off" by changing its shape or structure.
If hormones travel all over the body, can they activate the wrong cell type?
Even though all cells get exposed to said hormone they may not have the functional (necessary) receptor.
How can hormones affect tissues?
Hormones can modify the physical structure or biochemical properties of its target cells. This target cells can be affected by one hormone, Slowly altering the cells metabolic functions, then the tissues and finally the organs.
transmission: Through gap junctions
Chemical mediators: Ions, small solutes, lipid soluble materials
Distribution of effects: Usually limited to adjacent cells of the same type that are interconnected by connexons.
Transmission: Through extracellular fluid
Chemical Mediators: Paracrine factors
Distribution of effects: Primarily limited to local area, where concentrations are relatively high. Target cells must have appropriate receptors.
Transmission: Through the circulatory system
Chemical Mediators: Hormones
Distribution of effects: Target cells are primarily in other tissues and organs and must have appropriate receptors.
Transmission: Across synaptic clefts
Chemical Mediators: Neurotransmitters
Distribution of effects: Limited to very specific area. Target cells must have appropriate receptors.
What type of molecule is a hormone
Steroid or amino acid-based
Master endocrine gland that regulates other endocrine organs
How are hormones regulated
Have no set chemical structure
As the glucose levels decrease _____ is released by the _______ so cells can take up glucose.