Structure of the Nervous System Flashcards
What is the neuraxis?
An imaginary line drawn through the center of the length of the central nervous system, from the bottom of the spinal cord to the front of the forebrain.
What is the anterior?
With respect to the central nervous system, located near or toward the head.
What is the posterior?
With respect to the central nervous system, located near or toward the tail.
What is the rosteral?
‘toward the back’ - with respect to the central nervous system, in direction along the neuraxis toward the front of the face.
What is the caudal?
‘toward the tail’ - with respect to the cns, in a direction perpendicular (meets at a right angle) to the neuraxis toward the top of the head or the back.
What is the dorsal?
‘Toward the back’ - with respect to the cns, in a direction perpendicular (meets at a right angle) to the neuraxis toward the bottom of the skull or the front surface of the body.
What is the lateral?
Toward the side of the body, away from the middle
What is the medial?
Toward the middle of the body, away from the side.
What is the ipsilateral?
Located on the same side of the body
What is the contralateral?
Located on the opposite side of the body
What is the cross section?
With respect to the cns; a slice taken at right angles to the neuraxis
What is the frontal section?
A slice through the brain parallel to the forehead
What is the horizontal section?
A slice through the brain parallel to the ground
What is the midsagittal plane?
The plane through the neuraxis perpendicular to the ground; divides the brain into two symmetrical halves.
What does the nervous system do?
Receive, integrate and transmit information
What is the central nervous system made up of?
Brain and spinal cord
What is the peripheral nervous system made up of?
Somatic and Autonomic
The human brain is made up of…
2 ceberal hemispheres, cerebral cortex, gyri, sulci, lateral fissure and longitudinal fissure
What are the four lobes of the brain?
Precentral gyrus, central fissure, postcentral gyrus, lateral fissue, superior temporal gyrus, cerebellum
What is the neuron?
The basic unit of structure and function in the nervous system
Where are neurons located?
in the CNS and PNS
What are the 3 types of neurons?
Sensory = respond to external stimuli and transmit sensory information to the cns. These neurons are afferent, meaning they detect information from the environment.
Motor neurons = carry messengers from the CNS to muscles and glands. These neurons are efferent.
Interneurons = transmit messenges to other neurons.
What do Oligodendrocytes do?
Make up the mylein sheath in the cns
What do Schwann cells do?
Make up the mylein sheath in the pns
What do microglia do?
Protect the brain from invading organisms and clean up dead tissue by causing an inflammatory effect in the brain.
If a neuron doesn’t have a mylein sheath, what happens?
Information transmission is slowed down. If the MS breaks down there is no recovery, this is seen in Parkinson’s disease.
What are Glial Cells?
Other cells in nervous system
What are Astrocytes?
They wrap around blood vessels in the CNS, which allow some chemcials from the blood into the brain and some chemicals from the brain into the blood. They provide neurons with physical support, nutrients and clear waste. They also module neuronal activity, communicate with other neurons and glial cells.
What are the two methods of signalling in neurons?
Within the neuron - electrical
From the cell body - down the axon - to nerve terminals
Between neurons - chemical
From nerve terminals - across the synapse - to receptors on adjacent target cell
What is chemical signalling in neurons?
Chemical signalling occurs in synaptic junction between neurons.
What is the role of the nerve membrane?
The nerve membrane defines the cell, creating the intracellular and extracellular fluid components.
What is the resting membrane potential?
An electrical difference that exists across the nerve membrane of inactive neurons
The inside of the neuron is..
Electronegative (-70 millivolts) relative to the outside
An inactive neuron is said to be..
Polarised
What does intracellular and extracellular fluid contain?
Positively and negatively charged particles called ions.
What are the most important ions?
Anions & Cations
What are anions?
Organic and chloride
What are cations?
Sodium and potassium
What causes resting membrane potential?
Ions are unequally distributed across the nerve membrane.
Electrical Transmission - Read only flash card
Strength of sodium transporter is proportional to membrane potential and is maximal at resting potential (-70mV) i.e. is voltage-dependent
Sodium transporter breaks down if membrane potential becomes and little less negative and this is what happens when the neuron is stimulated.
Normally excluded sodium (Na+) ions rush into the cell and briefly reverse the normal polarity.
The inside of the cell briefly becomes positive with relation to the outside of the cell
The active neuron is said to be depolarized
