Chapter 4: CNS, PNS, Neuron Structure & Function Flashcards
What is the CNS? What does it do?
The central nervous system comprises the brain and the spinal cord. It enables the brain to communicate with the rest of the body by conveying messages from the brain to the PNS, and vice versa.
What is the PNS? What does it do?
The peripheral nervous system has 2 subdivisions;
The somatic NS
The autonomic NS
It’s two functions are:
-To communicate info from the body’s organs, glands, and muscles to the CNS, from both the outside world (sensation on the skin via sensory neurons), and the inside world (aches and pains.)
-To communicate info from the CNS to the body’s organs, glands, and muscles via motor neurons.
What is the ANS? What does it do?
Consists of the SNS and PNS, which both affect the same tissues and organs in opposite ways.
Involuntary system that is responsible for the communication of the info between the CNS and the body’s non-skeletal muscles.
What is the SNS branch of the ANS?
The sympathetic NS is like an emergency nervous system that becomes active when the organism perceives itself to be in danger.
It has an essential role in an organisms survival because it readies the body for actions such as running away, fighting the threat, or remaining (freezing). This is the fight, flight, or freeze response.
What is the PNS branch of the ANS?
The parasympathetic NS operates in circumstances where it is calm.
It is responsible for maintaining automatic daily bodily functions such as digestion, normal breathing, and normal heart rate. This functioning is known as homeostasis.
What are neurons?
Neurons receive information from other neurons, process this information, then communicate it to other neurons.
They are generally comprised of dendrites, the soma and the axon.
What is the soma?
The cell body. Largest part of the neuron, controls metabolism and maintenance of the cell.
What is the axon?
A nerve fibre which electric impulses are conducted from the cell body (soma) to other cells.
What are glial cells?
They hold neurons together, surrounding and supplying nourishment and oxygen to them.
They also remove dead neurons, and insulate one neuron from another, increasing the speed of transmission between nerve impulses.
What is myelin?
A fatty substance that covers the axon to insulate it from the surrounding fluid and from other neurons.
What is a synapse?
The connection between two neurons.
What is synaptic pruning?
Involves the elimination of excess neurons and synapses. That is, those that have not established a connection with a neighboring cell will die.
What is myelination?
A process where the axons of the neurons in the child’s brain become insulated by myelin.
What is the SNS?
Somatic nervous system.
The somatic nervous system is responsible for movement of voluntary muscles. This system carries nerve impulses back and forth between the central nervous system.
