The nervous system can be divided in to two major divisions:
CNS consist of the brain and spinal cord
PNS consist of all the nervous tissue outside the CNS
Communication link between the CNS and various parts of the body.
PNS.
Carries information about the different tissues of the body to the CNS and delivers commands from the CNS to other body tissues.
Enumerate the division of the nervous system.
CNS/PNS
PNS- Sensory/Motor↩️
Motor- Somatic/Autonomic↩️
Autonomic- Sympathetic/Parasympathetic
True or False
The ENS can function without input from the CNS or other parts of the PNS.
True
What are the two types of cell that makes up the nervous system?
neurons and glial cells
Receive stimuli,conduct action potentials and transmit signals to other neurons or effector organs.
Neurons or the nerve cells
Part's of a nerve cells:
Cell body that contains the nucleus and other organelles of a neuron.
Dendrites that receive information from other dendrites.
Axon where the stimuli travels to or fro the cell body.
The axon can be surrounded by a highly specialized insulating layer called...
myelin sheath
What are the types of neuron?
Multipolar- has a lot of dendrites
Bipolar- has two dendrites
Pseudo-unipolar- have a single process extending from the cell body. One extending to the CNS one extending to the PNS.
Are supportive cells of the CNS and PNS,these cells do not conduct action potentials. Instead they enhance neuron function and maintain normal conditions within the nervous system.
Glial cells
TRUE or FALSE
Most glial cells retain the ability to divide where as neuron do not.
True
There are four types of glial cells in CNS:
Astrocytes
Oligodendrocytes
Ependymal
Microglia
The major supporting cells in the CNS, it participates with the blood vessel endothelium to form a permeability barrier,called the blood brain barrier.
Astrocytes
Astrocytes help limit damage to neural tissue; however the repair process can form a scar that blocks regeneration of damaged axon.
TRUE or FALSE
TRUE
Line the fluid filled cavity within the CNS.
Ependymal cells
The immune cells of the CNS. They help protect the brain by removing bacteria and cell debris.
Microglia
The glial cells of the PNS:
Satellite cells
Schwann cells
A glial cell of the PNS that provided an insulating material around the axon.
Schwann cells
Provide support and nutrition to the neuron and protect the neurons from heavy-metal poisoning.
Satellite cells
A glial cells of the CNS that provides an insulating material that surrounds the axons.
Oligodendrocytes
TRUE or FALSE
The myelin sheath is produced by the cell process of oligodendrocytes and Schwann cells.
True
__________ increases the speed and efficiency of action potential generation along the axon.
Myelination
A nerve tissue that has little myelinated sheath.
Gray matter
The gray matter on the surface of the brain is called the...
cortex
The gray matter deeper in the brain is called the...
nuclei.
PNS also contains gray matter called the...
ganglion
A nervous tissue that has a lot of myelinated sheath.
The white matter.
TRUE or FALSE
The white matter of the CNS form nerve tracts or conduction pathways, which propagates action potential from one are of the CNS to another.
True
Basic types of ion channels
1.Leak channels and
2.Gated channels
____________channels are opened by specific signals.
Gated channels
__________channels are always open.
Leak
The ________ of the cell are more positively charged, while the _________ are always negatively charged.
outside
inside
Is a junction where the axon of one neuron interacts with another neuron or with cells of an effector organ.
Synapse
Parts of the synapse:
1.Presynaptic neuron - sender of signal
2.Postsynaptic neuron -receiving signals
3.Synaptuc cleft- the gap separating pre and post synapse.
Illustrate the process of communication at the synapse.
1. When action potential reaches the voltage gated Ca+ channels opens, and Ca+ moves into the cell.
2.The influx of Ca²+ causes the release of neurotransmitters by exocytosis.
3.The neurotransmitters diffuse across the synaptic cleft towards the post synaptic membrane.
4.The neurotransmitters then bind to specific receptor molecules on the postsynaptic membrane. The binding of neurotransmitters to these membrane receptors causes chemically gated channels for Na+, K+,or Cl- to open or close in the post synaptic membrane.
Neurotransmitters normally remain in the synaptic cleft indefinitely.
TRUE or FALSE
False. Neurotransmitters do not remain in the synaptic cleft for long. They can either be transported back to the presynaptic neuron for re-up take. Thus their effect on the target cells are typically very short-term.
Within the CNS neurons are organized to form pathways ranging from relatively simple to extremely complex.
What are these neuron pathways?
Converging pathway
Diverging pathway
This neuronal pathway allows information transmitted in more than one neuronal pathway to converge into a single pathway.
Converging pathway
This neuronal pathway allows information transmitted in one pathway to diverge into two or more pathways. The axon from one neuron divides and synapses with more than one other post synaptic neuron.
Diverging pathway
The ______consists of myelinated axons.
White matter
White matter in each half of the spinal cord is organized into three columns :
dorsal column
lateral column
ventral column
Each column of the spinal cord contains ascending and descending tracts or pathways.
__________ consists of axons that conduct action potential towards the brain.
__________ consists pf axon that conduct action potentials away from the brain.
Ascending - towards the brain
Descending - away from the brain
It is shaped like an H with 3 horns namely :
1.
2.
3.
