Lecture 2: Introduction to Neurophysiology Flashcards
In both the CNS and PNS, there are two nervous systems. What are these called?
somatic nervous system and autonomic nervous system
What is the major function of the somatic nervous system?
this is for stuff we are aware of/have control over
What is the major function of the autonomic nervous system?
this is for stuff we are not aware of/can’t control
What are the two divisions of the somatic nervous system?
afferent (somatic sensory division)
efferent (somatic motor division)
What are the two divisions of the autonomic nervous system?
afferent (visceral sensory division)
efferent
What are the two divisions of the efferent autonomic nervous system?
sympathetic and parasympathetic nervous system
What are the functions of the sympathetic nervous system (efferent autonomic nervous system)?
fight or flight, prepares the body for acute/stress response
What are the functions of the parasympathetic nervous system (efferent autonomic nervous system)?
rest and digest, prepares the body for restful situations
The dorsal root ganglia are part of which division of the spinal cord?
somatic (afferent)
As well as the dorsal root ganglia, there are autonomic ganglia. What are these called?
sympathetic ganglia
parasympathetic ganglia
Describe the somatic nervous system (voluntary control of skeletal muscle) organisation
- how many neurons between the brain and the effector?
- where is the UMN cell body located? Where is its axon located?
- where is the LMN cell body located? Where is its axon located?
- are they myelinated?
- what are the neurotransmitters that are released?
- 2 neurons between the brain and the effector
- the UMN cell body is in the brain and its axon is in the spinal cord
- the LMN cell body is in the spinal cord and the axon is in the PNS (sensory neuron)
- both neurons are myelinated
- the LMN releases ACh to the effector
Describe the parasympathetic nervous system (autonomic) organisation
- how many neurons between the brain and the effector?
- where are the cell body located? Where is its axon located?
- where is the LMN cell body located? Where is its axon located?
- are they myelinated?
- what are the neurotransmitters that are released?
- where is the synapse?
- 3 neurons between the brain and the effector
- neuron 1 has the cell body in the brain, axon in the spinal cord
- neuron 2 has the cell body in the spinal cord, axon in the PNS
- neuron 3 has both the cell body and axon in the PNS
- neuron 2 is long and myelinated, neuron 3 is short and un-myelinated
- neuron 2 and 3 synapse in the parasympathetic ganglion which is distant from the CNS
- neuron 2 (presynaptic) releases ACh to neuron 3 (postsynaptic)
- neuron 3 releases ACh to the effector
Describe the sympathetic nervous system (autonomic) organisation
- how many neurons between the brain and the effector?
- where are the cell body located? Where is its axon located?
- where is the LMN cell body located? Where is its axon located?
- are they myelinated?
- what are the neurotransmitters that are released?
- where is the synapse?
- 3 neurons between the brain and the effector
- neuron 1 has the cell body in the brain, axon in the spinal cord
- neuron 2 has the cell body in the spinal cord, axon in the PNS
- neuron 3 has both the cell body and axon in the PNS
- neuron 2 is short and myelinated, neuron 3 is long and un-myelinated
- neuron 2 and 3 synapse in the sympathetic ganglion which is close to the CNS
- neuron 2 (presynaptic) releases ACh to neuron 3 (postsynaptic)
- neuron 3 releases noradrenaline to the effector
On which side of the brain is the stimulus recorded?
on the opposite side of the brain from the one where the stimulus occurred
Where is the stimulus mapped in the brain?
in the primary somatosensory cortex
Where does the primary somatosensory cortex send signals to?
to the secondary somatosensory cortex to process the information
Describe how the body is mapped in the brain
the parts of the body with more receptors to perceive information (such as on the fingers) of the face are mapped larger in the somatosensory cortex compared to other parts of the body (such as the back) that does not perceive information and have as many receptors
Are both neurons and glia excitable?
no, only the neurons are
What three things do neurons have?
axons, dendrites, synapses
What features do neurons have that allow them to have ionic excitability?
K+ ion channels
Na+ ion channels
Na+/K+ ATPase
What other features do neurons have?
transporters and synapse specialisation
Are glia excitable?
no
If glia are not excitable, what are they used for?
they maintain the local environment and support the neurons
What are some features of glia?
they have myelin
What are some of the roles of glia?
they maintain the metabolism of the neurons and maintain the cerebrospinal fluid
Do glia have a resting membrane potential?
yes, despite not being excitable
Despite not being excitable, glia have a resting membrane potential, what allows them to have this?
K+ channels,
Na+ channels
Na+/K+ ATPase
What other features do glia have?
they express transporters
What are the four types of glia?
oligodendrocytes/Schwann cells
ependymal cells
astrocytes
microglia
What is the function of oligodendrocytes/Schwann cells?
they wrap around the axon to form the myelin sheath
What is the function of astrocytes?
they maintain the micro environment and form part of the blood-brain barrier
What is the function of the microglia?
mount the CNS immune response
What is the function of the ependymal cells?
it forms the ventricular epithelium
What is the purpose of saltatory conduction?
it increases the speed of the action potential propagation
What are the two types of synapses?
electrical (gap junction)
chemical
Describe an electrical synapse (gap junction)
this is the gaps between the neurons where the membranes are very close and channels are in the membrane that connect one to another to allow the flow of ions between adjacent neurons. This is very fast
Describe a chemical synapse
an action potential arrives at the axon terminal and depolarises it to allow Ca2+ to flow into the terminal of the presynaptic neuron. This influx of Ca2+ promotes vesicles to move to the cell membrane. The neurotransmitter is released across the cleft and is received on the post-synaptic neuron which activates the neuron to conduct an action potential (of there is sufficient synaptic activation)
What is the function of the pre-frontal cortex (right at the front of the brain)?
aggression and emotion
What is the function of the basal ganglia?
voluntary movement
What are the basal ganglia?
group of structures found deep within the cerebral hemispheres
What is the function of the hypothalamus?
neuroendocrine and autonomic control
What is the function of the brainstem?
autonomic/somatic regulation
What is the function of the cerebellum?
integration of sensory and motor information for smooth controlled movement
What is the function of the reticular formation?
arousal
What is the function of the limbic system? This includes the amygdala and hippocampus
language, learning, emotion, short and long term memory
What is the function of the corpus callosum?
communication between two hemispheres
What is the function of Broca’s area?
speech production
What is the function of the auditory association area?
it monitors sensory activity in the auditory cortex and recognises sounds such as spoken words
What is the function of the primary auditory area?
monitoring sound formation
What is the function of Wernicke’s area?
language comprehension
What is the purpose of the visual cortex?
receives info from the lateral geniculate bodies
What is the purpose of the visual association area?
it monitors the patterns of activity in the visual cortex and interprets the results
Afferent information that enters the spinal cord within the somatic nervous system, crosses over at which level?
at the spinal cord
Where is the primary motor cortex?
in the precentral gyrus
What is the function of the primary motor cortex?
direct voluntary movement by controlling somatic motor neurons in the brainstem and spinal cord
Where is the primary somatosensory cortex?
in the post central gyrus
What is the function of the primary somatosensory cortex?
neurons here somatic sensory information from receptors for touch, pressure, pain, vibration or temperature
