What are the two types of physiological signals?
electrical signals-changes in membrane potential, chemical signals-secreted into ECF, most communication
Communication can occur _____cells, _______ cells and from one _____ to another.
between, within, organ
What are ligands?
specific chemical messengers synthesised by specialised cells to serve a designated purpose,
What do chemical messengers include?
amines, amino acids, steroids, poypeptides (some instances lipids, purine nucleotides and pyramiding nucleotides)
What are the different types of chemical messengers?
autocrines, paracrines, neurotransmitters, hormones, neurohormones
What is paracrine communication?
chemical acts on another cell which is located close to the cell from which it is released
What is endocrine communication?
chemical acts on another cell which is locate far away from the cell which it is released, utilised bloodstream as a transport system
What is autocrine communication?
chemical acts on same cell from which it is released, often a mechanism for limiting release of the chemical
What are characteristics of paracrines?
derived from individual cells, effect on neighbouring cells in immediate environment of their site of secretion, don't enter blood as inactivated by enzymes
What is an example of a paracrine?
Histamine released by mast cell (connective tissue) dilates blood vessels in the vicinity
How do the nerve cells work?
electrical signal travels along a nerve cell until it reaches the end of the cell where it is translated into a chemical signal secreted by the neuron
What are the 4 components of the chemical communication system?
neurotransmitters, hormones, neurohormones, cytokines
What do neurotransmitters do?
provide communication between one neuron and another or between a neuron and its effector cell
What is a chemical signal called a neurotransmitter?
if the chemical signal diffuses from the nueron across a narrow extracellular space to a target cell
What cells do neurotransmitters act on?
act locally on adjoining target cell, may be another neuron, a muscle or a gland
Are neuronal signals accurate?
Yes neuronal signals through neurotransmitters can be restricted to an individual cell.
Is neuronal communication fast?
Yes neuronal communication can be very rapid, essential for locomotion
What are the two classes of neurotransmitters?
excitatory neurotransmitters and inhibitory neurotransmitters
What do excitatory neurotransmitters do?
cause depolarisation of postsynaptic membranes, promote action potentials
What do inhibitory neurotransmitters do?
cause hyper polarisation of postsynaptic membranes, suppress action potentials
What are examples of morphine like substance neurotransmitters?
endorphins, enkephalins, endomorphines, dymorphines
What are characteristics of hormones?
cell to cell communication, made in glands/cells, transported by blood, activates physiological response, distant target tissue receptors, provide communication that allows regulation of other cells
What do hormones control?
rate of enzymatic reactions, transport of ions or molecules across cell membranes, genes expression and protein synthesis
How do the tyrosine derivatives exist in the body?
thyroid hormones use transport protein, catecholamines stored in performed vesicles or can exist in the plasma in free form