Nervous coordination in mammals

Hope it helps! Just some class notes that I made.

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  • Created on: 10-02-09 13:59
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Nervous Coordination in Mammals
The nervous and endocrine systems perform the function of communication and
coordinate all the actions of cells, tissues and organs within the body in response
to internal or external environment changes.
The nervous system consists of two main types of cells-
1. Neurones- cells which are adapted to carry nerve impulses
2. Neuroglia- cells which provide structural and metabolic support to
neurones, these include Swann cells.

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Each neurone consists of-
A cell body containing the nucleus and most of the organelles, dense
clusters of endoplasmic reticulum, responsible for maintaining the cell. The
cytoplasm surrounding the nucleus is known as the perikaryon and contains
granules known as Nissl substance.
A long process or axon stretching out of the cell, sometimes over a very
long distance which is responsible for transmitting signals from the neurone
to other cells (away from the cell body).…read more

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However there is a greater concentration of potassium ions on the inside.
There is a greater concentration of chloride ions on the outside.
The large negatively charged organic ions are only on the inside.
This is because in resting state the permeability of the membrane to potassium is
relatively high due to the presence of protein channels which let the potassium
ions pass through and are attracted by the negative charge inside the axon.…read more

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The membrane must then be repolarised and so the sodium channels
close again and the potassium channels open.
This allows the potassium ions to rush at and the resting potential is
restored however first there is a slight `potassium overshoot'.
This causes the membrane potential to become slightly lower than its
normal resting value, this is called hyperpolarisation.
The resting potential is then gradually restored as sodium and potassium
ions return to their resting concentrations.…read more


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