The Nervous System, Chapter 11, Anatomy and Physiology

Central Nervous System
Central Nervous System
(CNS) Consists of the brain and spinal cord
Peripheral Nervous System
Peripheral Nervous System
(PNS) Consists of all nerves and receptors that are not part of the brain or spinal cord.
What are the four major parts of the brain?
What are the four major parts of the brain?
Cerebrum, Cerebellum, Brain Stem, and Diencephalon
What are the three functions of the nervous system?
What are the three functions of the nervous system?
Sensory Function (Afferent), Integrative Function, and Motor Function (Efferent)
What is a Sensory Function (Afferent)?
It carries information from the PNS to the CNS.
What is an Integrative Function?
When the brain is processing the information.
What is a Motor Function (Efferent)?
It carries the motor commands from the CNS to the PNS.
What are the two types of cells in the nervous system?
Neurons and Neuroglia (glial cells).
Neurons
Neurons
It transmits the nerve impulse. Does not replicate nor replace themselves when injured.
Neuroglia (glial cells)
Neuroglia (glial cells)
They are the most abundant nerve cell that supports and nourishes the neurons.
Parts of a Neuron
Parts of a Neuron
Dendrites, Cell body, Ganglion (ganglia), Axon, Axon terminals (synaptic knobs), Myelin sheath (myelin), Schwann cells, and Nodes of Ranvier.
Dendrites
Dendrites
Branchlike part of the neuron that transmits the nerve impulse toward the cell body.
Cell body
Cell body
Located in the CNS and contains DNA.
Ganglion (ganglia)
Group of cell bodies in the PNS.
Axon
Axon
Carries impulses away from cell body to the target organ.
Axon terminals (synaptic knobs)
Axon terminals (synaptic knobs)
Ends of the axon that stores neurotransmitters.
Myelin sheath (myelin)
Myelin sheath (myelin)
White fatty material that insulates the axon and speeds up nerve impulses.
What is the difference between Myelinated axon and Unmyelinated axon?
What is the difference between Myelinated axon and Unmyelinated axon?
Myelinated axons have myelin and unmyelinated axons do not contain myelin.
White matter
White matter
Myelinated axons
Gray matter
Gray matter
Unmyelinated axons
Interneurons
Interneurons
Transmit nerve impulses from one neuron to another.
What are the four types of cells in the CNS?
What are the four types of cells in the CNS?
Astrocytes, Oligodendrocytes, Ependymal cells, Microglia
Astrocytes
Astrocytes
Help maintain our blood brain barrier.
Oligodendrocytes
Oligodendrocytes
Produces myelin in the CNS, can produce enough myelin for 70 different axons
Ependymal cells
Ependymal cells
Line the cavities within the brain and contain cilia to keep the cerebral spinal fluid moving.
Microglia
Microglia
Cleans up the debris in the CNS.
Satellite cells
Satellite cells
Surround neuron cell bodies in the ganglia of the PNS. Help regulate the chemical environment of the neurons.
Schwann cells
Schwann cells
Produce myelin in the PNS.
Nodes of Ranvier
Nodes of Ranvier
Gaps between the myelin and is the only place that a nerve impulse can happen.
Blood brain barrier
Made up of tight junctions which prevent toxic substances from entering the blood stream in our brain.
Nerve impulses
Electrical signal from a neuron to another structure.
Action potential
Action potential
Nerve impulse.
Potassium (K+)
We have a lot of potassium on the inside of our cells, which can leak out.
Sodium (Na+)
A lot of sodium is on the outside of our cells.
Polarization
Polarization
The resting state of a neuron, the inside of the cell is more negative than the outside of the cell.
Depolarization
Depolarization
Sodium ions are flooding into the cell.
Repolarization
Repolarization
Potassium is leaving the cell but leaves slowly.
Refractory period
Refractory period
An action potential cannot take place because the axon is busy and directs the action potential to continue down the axon.
All-or-nothing manner
Action potential does not lose strength with distance.
Saltatory conduction
Saltatory conduction
When the action jumps from one Node of Ranvier to the next.
Synapses across neurons
Synapses across neurons
Nerves never touch anything.
Synaptic cleft
Synaptic cleft
The space between the nerve and the next structure.
Neurotransmitters
Neurotransmitters
Chemicals that send a message from the nerve to another structure. Acetylcholine (Ach) and Norepinephrine (NE)
Receptor sites
Receptor sites
Locations on a receptor neuron into which a specific neurotransmitter fits like a key into a lock.
Events at the Synapsis
Events at the Synapsis
1. The nerve impulse travels along neuron A to its axon terminal.
2. The neurotransmitter is released into the synaptic cleft.
3. Neurotransmitter travels across the synaptic cleft and binds to the receptor sites.
4. The nerve impulses travels toward the cell body and axon of neuron B.