Transcript Nervous System Overview

Nervous System
Neuron (nerve cell)
Structure
Function
Cell Body
Central part of the neuron. It
contains the nucleus of the cell.
where most protein synthesis
occurs.
Dendrites
cellular extensions where the
majority of input to the neuron
occurs.
Axon
cable-like projection carries nerve
signals. Extensive branching,
enables communication with many
target cells.
Schwann Cell / Myelin Sheath
Schwann cells wrap around the
axon to form the myelin sheath.
The myelin sheath insulates the
axon and speeds up nerve impulses
Axon Terminals
contains synapses, where
neurotransmitter chemicals are
released in order to communicate
with target neurons.
Part II
• 1. Electrical signals that are transmitted by the
neuron are called neural signals.
• 2. The junction between 2 neurons is called the
Synapse.
• 3. The transmitting cell is called the sensory
neuron.
• 4. The receiving cell is called the motor neuron.
• 5. Membrane potential is: the charge inside of a
neuron, relative to the outside while resting or
unstimulated.
Part II
• 6. In a resting nerve cell, the outside of the cell
membrane is electrically positive with respect to
the inside of the cell.
• 7. In a resting nerve cell, the concentration of
sodium ions is higher outside the cell
membrane than within the cell.
• 8. In the are of the nerve impulse, the cell
membrane becomes permeable to sodium ions.
• 9. In the area of the nerve impulse, the outside
of the cell membrane becomes electrically
negative with respect to the inside.
Part II
• 10. How are sodium ions moved out of the
neuron? There is a pump that uses energy to
move three sodium ions out of the neuron for
every two potassium ions it puts in.
• 11. What role do Potassium ions play in action
potential? At rest, potassium ions (K+) can
cross through the membrane easily. Also at rest,
chloride ions (Cl-)and sodium ions (Na+) have a
more difficult time crossing. Potassium ions help
to pump sodium into the cell to change the
charge.
Part II
• 12. What is the refractory period? It is the
amount of time it takes for an excitable
membrane to be ready for a second
stimulus once it returns to its resting state
Part III - CNS
• The Central
Nervous
System (CNS)
is composed
of two parts:
• brain
• spinal cord
Part IV - PNS
• The Peripheral
Nervous System
(PNS) consists of:
• somatic nervous
system (voluntary)
• autonomic nervous
system (involuntary)