The central nervous system (CNS) is composed of
Brain and spinal cord
What are the two main divisions of the nervous system?
Central nervous system and peripheral nervous system
The peripheral nervous system consists of
Vast network of nerves Throughout the body
The peripheral nervous system is divided into
Sensory (afferent) division and motor (efferent) division
What is the function of the sensory (afferent) division?
Carries signals from nerve endings to CNS
What is the function of the motor (efferent) Division?
Transmits information from CNS to rest of body
The sensory (afferent) is further divided into what 2 divisions & what are their roles?
Somatic sensory - Carries signals from skin, bones, joints,muscles
Visceral sensory - Carries signals from viscera of heart, lungs, stomach, and bladder
*Motor (efferent) division is further divided into what 2 divisions & what are their roles?
Somatic motor - Allows voluntary movements of skeletal muscles
Autonomic motor - provides “autonomic” Activities such as control of blood pressure and heart rate
Autonomic motor is further divided into
Sympathetic division and parasympathetic division
*What is the role of the sympathetic division?
Arouses the body for action “fight or flight”
*What is the role of the parasympathetic division?
Has a calming effect “rest & digest”
Describe the two types of cells that make up the nervous system
Neurons - Excitable, impulse conducting cells that perform the work of the nervous system
Neuroglia – protect the neurons
What are the five major types of glia, and what part of nervous system do they reside in?
CNS - Oligodendrocytes, ependymal cells, microfilm, astrocytes
PNS - Schwann cells
*What are the three classes of neurons and their functions?
- Sensory neurons - detect stimuli (such as touch, heat,cold, or chemicals) and then transmits that information to the CNS
- Interneurons - Connect the incoming sensory pathways with the outgoing motor pathways
- Motor neurons - relay messages from the brain to the muscle or gland cells
Control centre of the neuron and contains the nucleus
Soma
Receives signals from other neurons and conducts the information to the cell body
Dendrites
Carries nerve signals away from the cell body
Axon
The axons of many (but not all) Neurons are encased in a ________ , which consist of _________ and acts to _________
Myelin sheath, consists of mostly lipid, acts to insulate the axon
What are the gaps in the myelin sheath called?
Nodes of Ranvier
The end of the axon branches extensively, with each axon terminal ending in a
Synaptic knob
Function of myelin
Help speed impulse conduction
Where are Schwann cells found?
In the PNS, Schwan cells wrap themselves around the axon forming myelin sheath
What is the name for the outermost layer of the schwann cell, which is essential for an injured nerve to regenerate?
Neurilemma
In the CNS, the myelin sheath is formed by
Oligodendrocytes
Extending from the end of the spinal cord is a bundle of nerve roots called the
Cauda equina
How many pairs of nerves branch out of the spinal cord
31
What do nerves from the thoracic region innervate?
Rib cage, abdominal muscles, and back muscles
What do the lumbar spinal nerves innervate?
Lower abdominal wall and parts of the thighs and legs
What is the name of the hole in the vertebrae where the nerves pass through?
Intervertebral foramina
What are the four main nerve networks (plexus) ?
Cervical plexus, brachial plexus, lumbar plexus, sacral plexus
What is the role of the autonomic nervous system?
Responsible for regulating the activities that maintain homeostasis. (Happen autonomously)
