Physiology: The Nervous System Flashcards
Central Nervous System (CNS) is made up of (structurally):
▪brain
▪spinal cord
Peripheral Nervous System (PNS) made up of:
▪cranial nerves and their branches ▪spinal nerves and their branches ▪ganglia ▪enteric plexuses ▪sensory receptors
what is a nucleus/nuclei:
-cluster of neuronal cell bodies in the CNS
what are ganglion/ganglia?
-cluster of neuronal cell bodies in the PNS
what is a tract?
-bundle of axons in the CNS
what is a nerve?
-bundle of axons in the PNS
what is grey matter composed of?
collections of cell bodies and UNmyelinated nerve fibres in the CNS
what is white matter composed of?
myelinated axons in the CNS
what does the spinal cord taper into at L2?
conus medullaris
what are the roots of the spinal nerves?
cauda equinas
Functions of the NS:
1) Sensory ▪detection and input 2) Integrative ▪processing/storing/analyzing of sensory info ▪decision-making 3) Motor ▪output
what are the two type of nervous cells?
1) Neurons
2) Neuroglia
Role of neuroglia?
▪support neurons
▪nourish “ “
▪protect “ “
what are the parts of a neuron?
dendrite, cell body, axon
function of a dendrite?
it is the input portion of the neuron
function of cell body AKA soma?
cell processes (e.g. protein synthesis)
the end of an axon divides into many fine processes called:
axon terminals
the swollen ends of some axon terminals:
synaptic bulb
a multilayered lipid and protein covering that speeds up signal (‘action potential’) conduction:
myelin
an electrical signal that travels along the cell membrane of a neuron:
action potential
Structural Classification of Neurons (3 of them) and why:
1) multipolar
2) bipolar
3) unipolar
of process extending from the cell body
all motor neurons are (structure):
multipolar
most neurons in the brain and spinal cord (structure):
multipolar
sensory neurons in the PNS are (structure):
unipolar
Functional Classification of Neurons-how classified and what types (3)?:
functionally, they are classified according to the direction in which the AP is conducted with respect to the CNS
1) sensory neurons
2) motor neurons
3) interneurons
Sensory Neurons a.k.a. (directional):
afferent neurons
Motor Neurons AKA (directional):
efferent neurons
Interneurons a.k.a.
association neurons
most interneurons are ______ polar
multi
the site of communication between two neurons or between a neuron and another type of cell:
synapse
2 types of synapses:
electrical and chemical
Electrical Synapses: APs conduct directly between the plasma membranes of adjacent cells through ______________________
gap junctions
the space between the communicating neurons _________________
synaptic cleft
chemical synapses are _________ (than electrical)
slower
Neuroglia of the CNS (4 types):
1) astrocytes
2) oligodendrocytes
3) microglia
4) ependymal cells
2 roles of astrocytes:
▪help form the blood-brain barrier (BBB)
▪provide nutrients to neurons
role of oligodendrocytes:
form/maintain the myelin sheath of CNS neurons
where are epydymal cells in the body?
they line the cavities of the brain and spinal cord
The neuroglia of the PNS are _________ cells:
Schwann
what cells form the myelin sheath of PNS axons?
Schwann cells
where does the spinal cord end, inferiorly?
L2
a small tube in the centre of the SC that contains CSF is the _______________
central canal
the horns of the grey matter of the spinal cord are called the:
- posterior (a.k.a. dorsal) horn
- anterior (a.k.a. ventral) horn
in white matter of spinal cord, _____ (a.k.a. _________) tracts consist of axons that conduct APs away from the brain
motor; descending
in white matter of spinal cord, _____ (a.k.a. _________) tracts consist of axons that conduct APs away from the brain
sensory; ascending
Brain Structure, 4 parts:
1) brain stem
2) cerebellum
3) diencephalon
4) cerebrum
3 regions of the brain stem:
3 regions: medulla oblongata, pons, midbrain
continuous with the SC, it is the part between the SC and the diencephalon:
brain stem
In brain: contains centres (nuclei) for the control of heart rate, blood pressure, breathing, swallowing, and vomiting
medulla oblongata
contains centres for the control of breathing
pons
contains centres for reflex visual activities (e.g. tracking moving objects, scanning stationary objects), hearing
midbrain
- a net-like formation of neural tissue that spreads throughout the brain stem
- contains the (RAS)
reticular formation
where is the reticular formation located?
brain stem
▪smoothes and coordinates skeletal muscle contraction
▪regulates posture and balance
cerebellum
Diencephalon includes 3 parts:
:a) hypothalamus b) thalamus c) epithalamus
what part of brain responsible for:
▪major regulator of homeostasis
▪controls and integrates the autonomic nervous system
▪hormone production
▪emotion and behaviour (with the limbic system)
▪eating, drinking
▪body temperature
▪circadian rhythm (a 24 hour cycle in the biochemical, physiological and/or behavioural processes of living things)
hypothalamus
what part of the brain is the major relay station for most sensory input to the cerebral cortex?
thalamus
what area of the brain contains the pineal gland and is involved in smelling (especially emotional responses to smells)?
epithalamus
which part of brain consists of:
▪an outer rim of grey matter (cerebral cortex);
▪an inner region of white matter(association areas); and
▪grey matter nuclei deep within the white (basal ganglia)
cerebrum
In brain:
▪contains sensory areas involved in perception
▪contains motor areas involved in the execution of voluntary movements
cerebral cortex
In brain are that:
•helps to regulate the starting and stopping of movements
•helps control subconscious contraction of skeletal muscles
•helps suppress unwanted movement
•helps to set resting muscle tone
basal ganglia AKA basal nuclei
three protective layers of CT encircle the brain and SC, what are they called as a unit?
meninges
what are the 3 layers of meninges?
1) dura mater –tough outer layer
2) arachnoid membrane –middle layer
3) pia mater –inner layer
in the PNS: damage to ________ and myelinated axons can be repaired if the cell body is intact and ________cells are active
dendrites; Schwann
can damaged neurons be repaired in the CNS?
mostly no
