52 Questions
What is the main function of neurons in the nervous system?
Processing information
Which type of glial cell is responsible for forming the blood-brain barrier (BBB)?
Astrocytes
What is the role of microglia in the nervous system?
Removing debris and waste by phagocytosis
What is the function of oligodendrocytes in the nervous system?
Myelinating CNS axons
What is the function of the thalamus?
Act as a final relay point for sensory information before transmission to the cortex and serves as a filter
What is the role of the hypothalamus in the nervous system?
Control the autonomic nervous system, regulate emotional and behavioral patterns, and control body temperature and circadian rhythms
Which part of the brain is responsible for adjusting postural muscles and fine-tuning conscious and subconscious movements?
Cerebellum
What is the function of the medulla in the brain?
Regulate vital functions such as heartbeat and breathing
Which part of the brain contains functional areas such as the sensory cortex, association areas, and integrative centers for complex analytical functions?
Cerebrum
What is the main function of the spinal cord in neural responses?
Participate in neural responses through spinal reflexes
How many pairs of spinal nerves are there in the spinal cord?
31
What is the composition of the nervous tissue?
Neurons and glia
Which part of the nervous system is protected by bone, meninges, and cerebrospinal fluid?
Central nervous system (CNS)
What is the function of the cranial nerves?
Innervate the head and neck
What is the role of the motor cortex and pre-motor cortex in the nervous system?
Coordinate voluntary movements
What is the division of the white matter in the spinal cord for conveying sensory and motor impulses?
Ascending and descending tracts
What is the primary cause of the resting membrane potential (RMP) in neurons?
K+ efflux and a small Na+ influx
What predicts the resting membrane potential (RMP) based on ion concentrations and assumes full permeability to the ion?
The Nernst equation
What equation considers the permeability of all ions relative to K+ and explains the RMP of neurons?
The Goldman constant field equation
How is the nerve impulse propagated in myelinated axons?
Salutatory conduction
What occurs during the absolute refractory period (RP) after an action potential (AP)?
The membrane is inexcitable
How do electrical synapses occur between neurons?
Through gap junctions, allowing direct ion movement between cells
What is the role of calcium ions in synaptic vesicle release of neurotransmitters?
Dependent on calcium ions
What is the time period after an action potential when it is difficult to generate a second action potential?
Refractory period (RP)
What are the different types of chemical synapses in the central nervous system (CNS)?
Axodendritic, axosomatic, axoaxonic, and dendrodendritic
What is the mechanism of neurotransmitter release in chemical synapses?
Neurotransmitter release into the synaptic gap
What is the evidence for the role of calcium ions in vesicle release?
Experiments with calcium chelators and fluorescence imaging
What predicts the resting membrane potential (RMP) based on ion concentrations and assumes full permeability to the ion?
The Nernst equation
Which neurotransmitter is primarily used by the parasympathetic nervous system?
Acetylcholine
What is the primary function of the sympathetic nervous system?
Initiating 'fight or flight' responses
Where do the preganglionic neurons of the parasympathetic nervous system originate?
Craniosacral outflow
What triggers depolarization to threshold in the action potential?
Local currents
What is the ionic basis of the action potential?
Increased Na+ permeability
Where do visceral afferents terminate, generating autonomic reflexes?
Brainstem nuclei
What is responsible for the release of adrenaline and noradrenaline into the blood?
Direct innervation by some sympathetic neurons
What is the function of the enteric division of the autonomic nervous system?
Regulating gastrointestinal function
What is the role of the autonomic nervous system in reflexes like baroreceptors?
Reacting to danger by overriding normal reflex control
What is the peak reversal of membrane potential in the action potential?
-60mV to +40mV
What is the primary function of the parasympathetic nervous system?
Governing 'rest and digest' activities
What is the primary function of the sympathetic nervous system in terms of innervation?
Dual antagonistic, single, and dual nonantagonistic innervation
What is the result of phosphorylation of synapsin proteins?
Release of vesicles from the cytoskeleton
Which proteins are involved in priming the vesicle prior to fusion and release of neurotransmitter?
Syntaxin and SNAP-25
What is the main effect of excitatory neurotransmitters on the postsynaptic membrane?
Depolarisation
What is the primary result of inhibitory transmitter release at an inhibitory synapse?
Hyperpolarisation of the postsynaptic membrane
What is the process by which multiple synaptic potentials combine within one postsynaptic neuron?
Synaptic integration
What determines whether an action potential is generated in a postsynaptic neuron?
The balance between excitatory and inhibitory influences
What ion channels do excitatory neurotransmitters typically open?
Na+ channels
What type of response is an excitatory postsynaptic potential (EPSP)?
A graded response
What is the term for the process where effects of the excitatory transmitter release at different synapses add together to give a larger total response?
Spatial summation
What is the result of repeated stimulation of a single excitatory synapse?
Increased peak of the EPSP
What is the primary effect of IPSPs on a postsynaptic neuron?
Hyperpolarisation
What is the primary mechanism by which neurotransmitters produce changes in postsynaptic potential?
Opening receptor-operated ion channels
Study Notes
Neurophysiology: Autonomic Nervous System and Action Potential
- The autonomic nervous system (ANS) regulates visceral functions and maintains internal homeostasis, consisting of sympathetic (SANS) and parasympathetic (PANS) divisions, and the enteric division.
- The SANS, responsible for "fight or flight" responses, has preganglionic neurons in the thoracolumbar outflow and utilizes acetylcholine and noradrenaline as neurotransmitters.
- The PANS, governing "rest and digest" activities, has preganglionic neurons in the craniosacral outflow and uses acetylcholine as its primary neurotransmitter.
- Both SANS and PANS have specific patterns of innervation, including dual antagonistic, single, and dual nonantagonistic innervation.
- Visceral afferents enter the spinal cord via the dorsal horn, terminating in various brainstem nuclei, thalamus, and hypothalamus, generating autonomic reflexes and controlling visceral homeostasis.
- The action potential (AP) is the transitory reversal of membrane potential, involving depolarization, repolarization, and hyperpolarization, driven by changes in ion permeability and voltage-gated channels.
- The ionic basis of the AP involves increased Na+ permeability, reaching the Na+ electrochemical equilibrium potential, which triggers depolarization to threshold by local currents.
- The AP peaks at a reversal of membrane potential from -60mv to +40mV, followed by inactivation of sodium channels and opening of voltage-regulated potassium channels, leading to repolarization.
- The ANS has overarching central control, with communication of information occurring through membrane phenomena, transitory reversal of membrane potential, and conduction of information along nerve cells.
- The ANS encompasses reflexes, such as baroreceptors, that react to danger by overriding normal reflex control, increasing heart rate, blood pressure, and cardiac output.
- The ANS is responsible for fast, predictable automatic responses to stimuli in the environment, such as spinal reflexes that involve the dorsal column pathway and information about joint sense and fine discriminatory touch.
- The SANS has exceptions in its organization, with some preganglionic neurons passing through paravertebral ganglia without synapsing and directly innervating the adrenal gland, leading to the release of adrenaline and noradrenaline into the blood.
Test your knowledge of the autonomic nervous system and action potential with this quiz. Explore the divisions of the ANS, neurotransmitters, innervation patterns, visceral reflexes, and the ionic basis of the action potential. Gain insights into the central control of the ANS and its role in generating fast, predictable responses to environmental stimuli.
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