Lecture 2 - Neurophysiology II Flashcards
what are the 2 divisions of the central nervous system?
somatic nervous system and autonomic system
what composes the central nervous system?
brain and spinal cord
what composes the peripheral nervous system?
cranial nerves and spinal nerves
what does the somatic nervous system consist of?
somatic sensory division (afferent) and the somatic motor division (efferent) both of these compose the somatic integration centres
what does the autonomic nervous system consist of?
visceral sensory division (afferent), sympathetic division (efferent) and the parasympathetic division (efferent), all compose the autonomic integration centres
what are the 2 divisions of the peripheral nervous system?
sympathetic nervous system and parasympathetic nervous system
what is the relationship between the peripheral nervous system + neuroendocrine system to the central nervous system?
the peripheral nervous system and neuroendocrine system have somatic and special receptors which detect a stimulus and relay it to the CNS
what are the effectors of the somatic nervous system?
skeletal muscle and visceral receptors
what are the effectors of the autonomic nervous system?
cardiac and smooth muscle; adipose and other tissues
what is the spinal reflex arc?
a stimulus is perceived in the skin sent by afferent signals to the brain from the dorsal root ganglion and the spinal cord. The reflex is processed at the level of the spinal cord resulting in stimulation of the motor neuron to the skeletal muscle effector. A response is produced through the efferent nerve of the agonist skeletal muscle results in withdrawal from the stimulus (reflex). The antagonist muscle acts as the inhibitor.
is the brain involved in the spinal reflex arc?
yes as it compares the actual response to the expected response and modulates to see if any further input is required
what are the divisions of the brain?
pre-frontal cortex basal ganglia (including thalamus) hypothalamus brainstem (including pons and medulla) cerebellum reticular formation limbic system (including amygdala and hippocampus) corpus callosum (part of the limbic system)
what is the function of the pre-frontal cortex?
aggression and emotion
what is the function of the basal ganglia (including thalamus)?
voluntary movement
what is the function of the hypothalamus?
neuroendocrine and autonomic control
what is the function of the brainstem (including pons and medulla)?
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 (including amygdala and hippocampus)?
language, learning, emotion and short and long term memory
what is the function of the corpus callosum (part of the limbic system)?
communication between the 2 brain hemispheres
what is the somatotopic map?
the somatotopic map represents how some areas of the body are more innervated in the somatosensory cortex due to areas with a larger number of sensory receptors such as the face/hands compared to the back/feet and everything sensed at one side of the body activates the other side of the brain
state the 6 major features of neurons?
1) excitable
2) store and pass on information
3) composed of axons and dendrites
4) form synapses between adjacent neurons
5) contain K+ ion channels and Na+ ion channels
6) resting membrane potential (RMP) is maintained by Na+/K+ATPase
state the 6 major features of glia?
1) non-excitable
2) located in the ventricles of the brain where CSF is stored to maintain and regulate CSF signalling in the CNS
3) composed of myelin
4) aid in metabolism and maintain the local environment
5) contain K+ channels
6) resting membrane potential is maintained Na+/K+ATPase
what are the 4 types of glia?
microglia
astrocytes
oligodendrocytes (and schwann cells)
ependymal cells
what is the function of microglia?
mount the CNS immune response
what is the function of astrocytes?
maintain the microenvironment and form part of the blood-brain barrier
what is the function of oligodendrocytes (and schwann cells)?
wrap around the axon to form the myelin sheath
what is the function of ependymal cells?
form the ventricular epithelium
what are electrical synapses (gap junctions)?
channels in the membrane that connect from one neuron to the other and when open allow for the flow of ions between adjacent neurons
what are gap junctions?
junctions between neurons where cell membranes are very close that form channels
what do electrical synapses allow in terms of communication?
rapid communication
what are the 5 key components of chemical synapses?
1) slower communication
2) relies upon chemical crossing the gap
3) complex series of events
4) neurotransmitter packed into vesicles
5) synapse strength can be modified
what occurs when an AP arrives at a chemical synapse?
AP arrives at axon terminal –> depolarises axon terminal to allow Ca2+ influx into the presynaptic terminal –> increased intracellular Ca2+ promotes the diffusion of vesicles within the cell membrane (takes time) –> diffuses across the synaptic cleft –> activates receptor –> mediates post synaptic response
