Module 13: Nervous System Flashcards
What are the support cells of the nervous system?
Neuroglia
Where are oligodendrocytes found and what do they form?
– For Mylan sheath in the spinal and brain cord
- Speed signal conduction
*Where are astrocytes found and what is their function?
4 functions
Extend through brain tissue
- Nourish neurons
- Help form blood-brain barrier
- Attach neurons to blood vessels
- Provide the structural support
*Where are Schwann cells found and what do they form?
Form Myelin sheath around nerves in PNS; form neurilemma
What is the role of microglia?
Perform phagocytosis, and engulf microorganisms and cellular debris
*What are the functions of the blood-brain barrier?
Allows small molecules to diffuse across to the brain, but blocks larger molecules. This helps protect the brain from foreign substances
What is the role of sensory (afferent) neurons?
Detects stimuli and then transmit information about the stimuli to the CNS
What is the role of interneurons?
Found only in the CNS, connect the incoming sensory pathways with the outgoing motor pathways.
- The connection made by these neurons make each of us unique and how we think, feel, and act
What is the role of motor (efferent) neurons?
Relay messages from the brain to the muscles or glands cells
What is the function of the cell body (soma)?
Control centre of the neuron and contains the nucleus
What is the function of dendrites?
Receive signals from other neurons and conduct the information to the cell body
What is the function of the axon?
Carries nerve signals away from cell body
What is the function of the myelin sheath?
– Consisting of mostly lipid, myelin acts to insulate the axon
- Help speed impulse conduction
In the PNS, What forms the myelin sheath?
Schwann cells
In the CNS, what forms myelin sheath?
Oligodendrocytes
Describe the nodes of Ranvier
- Gaps in the myelin sheath, the current evenly spaced intervals
- Ion flow across the membrane occurs only at the nodes of Ranvier. As a result, the action potential signal jumps along the axon, from node to node
What is the function of the synaptic knob?
- Located at the ends of axon terminals;contain a neurotransmitter
- At the synaptic knob, the action potential is converted into a chemical message which, in turn, interacts with the recipient neuron or effector
when ions with opposite electrical charges are separated by a membrane, this is called
Membrane potential
When a membrane has an excess of positive ions on one side and an excess of negative ions on the other, it is said to be
Polarized
What is essential for an injured nerve to regenerate?
Neurilemma
What is the division of the nervous system that provides for the bodies automatic activities?
Autonomic motor
What is the division of the nervous system that carries signals from the organs?
Visceral sensory
What is the division of the nervous system that carries impulses to and from skeletal muscles?
Somatic sensory
Gray matter appears gray because of what?
Lack of myelin
Is it white matter or gray matter that contains bundles of axons called tracts that carry impulses from one part of the nervous system to another
White matter
The small space between the outer covering of the spinal cord and the vertebrae is called
Epidural space
List the three layers of meninges, starting with the innermost layer
- Pia mater
- Arachnoid mater
- Dura mater
A nerve consists of many nerve fibres (axons) encased by ?
Connective tissue
Nerve fibres are gathered together in bundles called what?
Fascicles
Area innervated by a spinal nerve
Dermatome
Plexus that innervates the lower part of the shoulder and arm
Brachial
Plexus that contains nerves that supply the muscles and skin of the neck, tops of the shoulders, and part of the head
Cervical plexus
Plexus that supplies the thigh and leg
Lumbar plexus
Largest nerve in the body
Sciatic nerve
The phrenic nerve, which Stimulates the diaphragm for breathing, is located in which plexus?
Cervical plexus
What are the key nerves travelling into the arm from the brachial plexus?
Axillary nerve, radial nerve, ulnar nerve, and the median nerve
Fibrous connective tissue that covers the spinal cord
Meninges
The nerves in the cervical region (C1-C8) innervate
Chest, head, neck, shoulders, arms, hands, diaphragm.
Nerves it thoracic region innervate (T1-T12)
Extend to the intercostal muscles of the rib cage, abdominal muscles, and back muscles
Nerves in the lumbar spinal region innervate
Lower abdominal wall and parts of the thighs and legs
Sacral region nerves innervate
Extend to the thighs, buttocks, skin of the legs and feet, and anal and genital regions
*What is the function of cerebrospinal fluid?
Constantly Flows through the CNS (brain and spinal cord)
- Provides nourishment*
- Removes metabolic wastes
- Cushions the brain against minor trauma
*What is the role of arachnoid villi in the flow of CSF?
The CSF is reabsorbed into the venous bloodstream by projections of the arachnoid mater into the dural sinuses - called arachnoid villi
*How is CSF formed?
CSF is formed by the choroid plexus (A network of blood vessels lining the floor or wall of each ventricle)
A minute opening which carries cerebrospinal fluid through the spinal cord is called
Central canal
Is the dorsal column an ascending or descending tract? What is its function?
Ascending tract
- Relays sensations of deep pressure and vibration as well as those needed to create awareness of the body’s position (proprioception)
Is the corticospinal tracts(also called pyramidal tracts) ascending or descending tract? What is its function?
Descending tract
- Responsible for is fine movements of hands, fingers, feet, and toes on the opposite side of the body
Is the spinocerebellar tract ascending or descending tract? What is it responsible for?
Proprioception
Is the extrapyramidal tracts an ascending or descending tract? What is its function?
Descending
- Group of tracks associated with balance and muscle tone
Is the spinothalamic tract an ascending or descending tract? What is its function?
Ascending
- Relays sensations of temperature, pressure, pain, and touch
*What are reflexes? What is the function of the reflex arc?
- Reflexes are a quick, involuntary, predictable response to a stimulus
- Reflexes employer neural circuit call the reflex arc, which bypass regions of the brain were conscious decisions are made
What is the role of the dorsal (posterior) nerve root which enters the dorsal horn of the spinal cord?
Contains fibres that carry sensory information into the spinal cord
Cell bodies of the dorsal neurons are clustered in a knot-like structure called
Ganglion
Fibres in the ventral (anterior) nerve roots exit from where and what is its role
Exit from the ventral horn to carry motor information out of the spinal cord
Because the autonomic nervous system target organs, is sometimes called the
Visceral motor system
What are the functions of the autonomic nervous system?
- Regulates activities that maintain homeostasis
- Send motor impulses to cardiac and smooth muscle and glands
The Ennis asserts control through visceral reflexes – similar to somatic reflexes, but instead of affecting a skeletal muscle, these reflexes affect…
An organ
Autonomic pathways employe two neurons to reach the target organ. What are these two neurons?
- Myelinated preganglionic neuron – extends from the brain stem or spinal cord to a ganglion
- Postganglionic neuron – In the ganglion, it synapses with a postganglionic neuron, here the neurotransmitter ACh is released
The sympathetic division is also called
The thoracolumbar division
The parasympathetic division is also called
The craniosacral division
