INTRO TO NERVOUS SYSTEM Flashcards
what is a nuclei?
functional clusters of nerve cell bodies
what is a tract?
groups of nerve axons
what are neurons/nerve cells?
excitable cells that communicate via electrical and chemical signals
what are glial cells and how common are they?
supporting cells that account for 90% of the cells in the nervous system
what is a unipolar neuron?
have a single projection from the cell body (rare in humans)
what is a bipolar neuron?
have 2 projections (an axon and a dendrite from the same cell body)
what is a pseudo-unipolar neuron?
subdivision of bipolar neurons, cell body branched off axon outside CNS in a ganglion
what is a multipolar neuron?
have multiple projections (one is the axon and the others are dendrites)
what is an efferent neuron?
transmit information from the CNS to the effector organs
what is an afferent neuron?
transmit either sensory information (outside) visceral information (inside)
what is an interneuron?
Located entirely in the CNS, go between sensory and effector, carry out functions within the brain
what is the function of glial cells?
Provide structural integrity for nervous system
how many types of glial cells are there?
5 types and only the Schwaan cells are located in the PNS
what are astrocytes?
support, nutrients, develop/maintain BBB
what are microglia?
small, mobile, macrophages for CNS
what are ependymal cells?
line cavities and fluid-filled spaces
what are oligodendrocytes?
form myelin around axons in the CNS
what are schwaan cells?
form myelin around axons in PNS
what is the CNS?
comprises the brain and spinal cord
what is the PNS?
comprises the spinal and cranial nerves
gives rise to the somatic and autonomic nervous systems
what is the SoNS?
Part of the PNS associated with the voluntary control of movement
what is the function of the SoNS?
Responsible for communicating info from outside the body
what 2 neurons are associated with the SoNS?
afferent (sensory) nerves that bring external information to the spinal cord
efferent (motor) nerves responsible for muscle contraction
what are the protective layers of the brain?
Skull
Cranial meninges
Cerebrospinal fluid
Blood brain barrier
what are the protective layers of the spinal cord?
Vertebral column
Spinal meninges
Cerebrospinal fluid
what are the meninges?
three connective tissue coverings that encircle brain and spinal cord
what is the dura matter?
tough, outer membrane
what is the arachnoid matter?
elastic, middle membrane, act as a cushion
what is the pia matter?
fine, inner membrane
what is the epidural space?
between dura mater and all of vertebral canal
what is the subdural space?
between dura mater and arachnoid mater and contains interstitial fluid
what is the subarachnoid space?
between arachnoid mater and pia mater
what is the CSF?
clear colourless liquid found in the brain and spinal cord
what is the function of the CSF?
acts as a cushion/buffer for the cortex providing protection of the brain inside the skull
what does the CSF contain?
small amounts of protein, glucose and potassium
large amounts of NACL
where is the CSF produced?
choroid plexus of the brain
what can the CSF be used for and why?
can be sampled to aid diagnosis of certain conditions
maintains its own pressure (which can be measured to diagnose or treat illness)
what are the ventricles?
4 cavities found in the brain
what is the central canal?
a long thin cylindrical cavity that runs the length of the spinal cord
what is located in the ventricles?
choroid plexuses
what do the choroid plexuses do?
fills the ventricles and subarachnoid space with CSF, following a cycle of constant production and reabsorption
how does the blood flow to the brain?
internal carotid and vertebral arteries
where about does the blood flow into the brain?
into dural sinuses
where does blood empty in the brain?
into internal jugular veins
how does blood flow to the spinal cord?
posterior intercostal and lumbar arteries
where does blood empty in the spinal cord?
into posterior intercostal and lumbar veins
how are tight junctions formed in the brain BV and what do they do?
astrocytes stimulate endothelial cells to develop tight junctions and this severely limits permeability to and from the CNS
what types of drugs is the BBB restricts to?
lipophilic drugs (can traverse the lipid membranes of cells)
what so brain epithelial cells have?
a number of carrier mechanisms transporting hydrophilic nutrients, amino acids
what is the BBB?
highly selective semipermeable memb barrier that separates the circulating blood from the brain and ECF in the CNS
what does white matter consist of?
neuronal axons (mostly myelyinated) - myelin is fatty so appears white
what does grey matter consist of?
neuronal cell bodies, dendrites, axon terminals, unmyelinated axons and glial cells
what occurs in the grey matter?
Synaptic transmission and neural integration
what is the spinal cord?
Long tubular bundle of nerve+supporting cells that extends from the brainstem, protected by the vertebral column
how many spinal nerves are there?
31 pairs
what are the sub-divisions of the spinal nerves?
cervical, thoracic, lumbar and sacral regions
what is the function of the spinal cord?
channel for both motor and sensory info
Centre for coordinating reflex actions
how is the grey matter organised in the spinal cord?
different neurons are located in different regions, includes one dorsal horn and one ventral horn on each side
where do afferent fibres originate?
in the periphery as sensory receptors
where do afferent fibres terminate?
in the dorsal horn where they synapse on interneurons/efferent neurons
where do efferent fibres originate?
in the ventral horn
where do efferent fibres travel to?
to the periphery, where they form synapses with effector organs e.g. skeletal muscles
what do tracts in the white matter do?
provide communication either between the levels of the spinal cord or between the brain and spinal cord
what do ascending tracts do?
transmit info from spinal cord to brain
what do descending tracts do?
transmit information from brain to spinal cord
what do the tracts link?
link the peripheral nerves to the brain
what is the forebrain?
largest, most superior part
divided into 2 hemispheres, contains the cerebrum and diencephalon
what is the brainstem?
connects the forebrain and cerebellum to the spinal cord
what does the brainstem contain?
Midbrain, Pons, Medulla oblongata
houses the reticular formation
where is the medulla oblongata?
sits directly above the spinal cord, connects to forebrain
what is the function of the medulla oblongata?
contains several centres that control autonomic (involuntary) functions including digestion, breathing and heart rate
where are the pons?
sits above the medulla, connects to cerebellum
what is the function of the pons?
acts as a relay station conveying info from the cerebral hemispheres to the cerebellum
where is the midbrain?
sits on top of the pons, connects to spinal cord
what is the function of the midbrain?
controls many of the sensory/motor functions including eye movement and the coordination of audio visual reflexes
what is reticular formation?
involved in many involuntary functions and is a network of interconnected nuclei and the reticular activating system (RAS)
what does the output of RAS do?
affects the activity of the cerebral cortex
what is the function of RAS?
Controlling our awareness, Attention, Wakefulness/sleep
Consciousness
where is the cerebellum?
Lies beneath the occipital lobe and behind the brainstem
what does the cerebellum contain?
extensive connections with the cerebral hemispheres and spinal cord
what is the function of the cerebellum?
control and coordination of movement control centre
where is the highest level of motor control found?
from the cortex
what do the basal ganglia and cerebellum provide?
feedback to the cerebral cortex and brainstem
where is the diencephalon?
Lies rostral to the midbrain and contains the thalamus and hypothalamus
what is the function of the thalamus?
processes most of the sensory info reaching the cerebral cortex from the rest of the CNS
what is the function of the hypothalamus?
involved in regulating autonomic (temperature, circulation, food intake), endocrine and visceral functions
what is the hypothalamus connected to?
limbic system – emotional behaviour
what does the cerebrum contain?
deep subcortical nuclei and cerebral cortex
what does the deep nuclei contain?
Basal nuclei (basal ganglia), Thalamus, Hypothalamus Those in the limbic system
what is the cerebral cortex?
Largest part of the brain
2 hemispheres connected by the corpus callosum
what does the cerebral cortex contain?
Highly convoluted layer of grey matter consisting of sulci and gyri
what does the frontal lobe control?
personality, voluntary motor activity
what does the temporal lobe contain?
senses of smell, hearing, taste
what does the parietal lobe control?
peripheral sensations
what does the occipital lobe control?
vision
how do complex functions occur?
require involvement of more than one lobe of cortex, but often concentrated in one hemisphere
what is the basal ganglia?
Collection of deep nuclei within the cerebral hemispheres, impact on motor control
what nuclei are involved in the basal ganglia?
Caudate nucleus
Globus pallidus
Putamen
Striatum
what does the basal ganglia do?
Helps to initiate and terminate movements, supress unwanted movements and regulate muscle tone
how is the function of the basal ganglia achieved?
by modulating activity in various descending pathways
where is the limbic system?
Lies underneath the cerebral cortex
what structures does the limbic system contain?
Amygdala, Hippocampus, Fornix, Cingulate gyrus
Potions of the thalamus and hypothalamus
what is the function of the limbic structures?
generate emotional states such as fear, arousal, rage, happiness and contribute to memory and learning processes
