NMJ, Neurotransmitters, and NS Overview
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Questions and Answers

What is the Neuromuscular Junction?

  • A synapse or connection between a motor neuron and a muscle fiber that leads to muscle contraction. (correct)
  • A type of neuron responsible for sensory information.
  • A location where muscle fibers are generated.
  • The point of communication between two motor neurons.

    • What are the 3 components of the neuromuscular junction (NMJ)?

  • Presynaptic terminal, synaptic cleft, and postsynaptic membrane (correct)
  • Muscle fiber, motor neuron, and synaptic vesicle
  • Dendrite, axon, and cell body
  • Synaptic vesicle, neurotransmitter, and ion channel

    • Where are high concentrations of calcium stored in the myocyte?

  • Sarcoplasmic reticulum (correct)
  • Mitochondria
  • Cytoplasm
  • Nucleus

    • Which of the following statements about the sarcoplasmic reticulum (SR) is true?

    <p>The SR structure surrounds the myofibrils, allowing storage and release of calcium directly at sites of actin and myosin overlap.</p> Signup and view all the answers

    What is the function of T tubules in muscle contraction?

    <p>They facilitate the conduction of action potentials into the muscle cell.</p> Signup and view all the answers

    What is the purpose of the Dihydropyridine (DHPR) and ryanodine receptors?

    <p>To facilitate the release of calcium ions from the sarcoplasmic reticulum</p> Signup and view all the answers

    What type of receptor is a nicotinic acetylcholine (ACh) receptor?

    <p>Ligand-gated ion channel</p> Signup and view all the answers

    Why are fetal nicotinic receptors also considered extrajunctional receptors?

    <p>Because they can be located anywhere in the muscle membrane, inside or outside the neuromuscular junction.</p> Signup and view all the answers

    When do fetal nicotinic acetylcholine receptors typically disappear?

    <p>After birth</p> Signup and view all the answers

    What type of receptors are muscarinic acetylcholine receptors? (select 2)

    <p>Metabotropic receptors</p> Signup and view all the answers

    Which of the following statements about muscarinic acetylcholine receptors (mAChRs) is true regarding their functions in the body? (select all that apply)

    <p>They primarily decrease heart rate.</p> Signup and view all the answers

    What is the positive effect of fetal nicotinic acetylcholine receptors (nAChRs) reappearing in muscle tissue?

    <p>They help the muscle adapt and recover by increasing sensitivity to acetylcholine (ACh).</p> Signup and view all the answers

    How do fetal nicotinic receptors contribute to muscle function after a denervation injury?

    <p>They compensate for reduced neural input by preventing muscle atrophy and maintaining muscle tone.</p> Signup and view all the answers

    Where are pre-junctional acetylcholine receptors located?

    <p>At the synaptic end bulb</p> Signup and view all the answers

    What is the role of pre-junctional ACh receptors?

    <p>To move Ach towards and modulate ACh release into the synaptic cleft</p> Signup and view all the answers

    What is true about post-junctional acetylcholine (ACh) receptors?

    <p>They can be activated by exogenous ACh.</p> Signup and view all the answers

    What causes upregulation of extra-junctional receptors?

    <p>All of the above</p> Signup and view all the answers

    What is the mechanism by which fetal acetylcholine receptors (AChR) are more sensitive to acetylcholine (ACh)?

    <p>Longer channel opening time</p> Signup and view all the answers

    What metabolic disorder is of concern in the presence of upregulated immature acetylcholine receptors (AChR)?

    <p>Hyperkalemia</p> Signup and view all the answers

    What is the resting membrane potential of a neuron?

    <p>-70 mV</p> Signup and view all the answers

    What is the movement of sodium and potassium in the Na-K pump?

    <p>3 Sodium moves out of the cell while 2 potassium moves in.</p> Signup and view all the answers

    What is the axolemma?

    <p>The outermost surface of the axon</p> Signup and view all the answers

    The influx of calcium through voltage-gated calcium channels cause ___ to fuse to synaptic vesicles.

    <p>Neurotransmitters</p> Signup and view all the answers

    What does it mean that action potentials are all or none?

    <p>They must meet a threshold potential to occur.</p> Signup and view all the answers

    Which type of muscle cells tend to have a longer refractory period in relation to contraction?

    <p>Cardiac myocytes</p> Signup and view all the answers

    What is the primary excitatory neurotransmitter in the central nervous system (CNS)?

    <p>Glutamate</p> Signup and view all the answers

    What are the excitatory responses associated with glutamate? (Select all that apply)

    <p>Motor neuron activation</p> Signup and view all the answers

    Glutamate does not cross the BBB so it must be synthesized in the brain

    <p>True</p> Signup and view all the answers

    What neurotransmitter can the brain convert glutamate to?

    <p>GABA</p> Signup and view all the answers

    Which of the following statements about glial cells is true?

    <p>They recycle glutamate by converting it into glutamine.</p> Signup and view all the answers

    What is the primary inhibitory neurotransmitter in the brain?

    <p>GABA</p> Signup and view all the answers

    What is the primary inhibitory neurotransmitter in the spinal cord and lower brainstem?

    <p>Glycine</p> Signup and view all the answers

    How is glycine formed from serine?

    <p>Through an enzyme-catalyzed reaction</p> Signup and view all the answers

    Which of the following serve as co-activators of the NMDA receptor? (Select all that apply)

    <p>Glutamate</p> Signup and view all the answers

    Which endogenous substances are associated with opioid-like activity? (select all that apply)

    <p>Enkephalins</p> Signup and view all the answers

    Where is substance P primarily found in the CNS?

    <p>Dorsal root ganglia</p> Signup and view all the answers

    What is Substance P associated with? (Select all that apply)

    <p>Pain perception</p> Signup and view all the answers

    Unconventional neurotransmitters are stored in synaptic vesicles

    <p>False</p> Signup and view all the answers

    Unconventional neurotransmitters may carry messages from postsynaptic to presynaptic neurons

    <p>True</p> Signup and view all the answers

    Which of the following are examples of gasotransmitters (gas signaling molecules)?

    <p>Nitric Oxide (NO)</p> Signup and view all the answers

    Which type of cannabinoid receptor is associated with the "high" effect?

    <p>CB1 receptors</p> Signup and view all the answers

    Which type of cannabinoid receptors are primarily located in the brain?

    <p>CB1</p> Signup and view all the answers

    What type of cannabinoid receptors are involved in immune system function and do not produce a 'high' effect?

    <p>CB2 receptors</p> Signup and view all the answers

    The human body produces _____ which are structurally similar to the molecules in the cannabis plant.

    <p>endocannabinoids</p> Signup and view all the answers

    What system is the first and last to develop in utero?

    <p>Nervous system</p> Signup and view all the answers

    What becomes the ventricular system in the mature brain?

    <p>Neural tube</p> Signup and view all the answers

    What structure becomes neural tissue in the mature brain?

    <p>Neural tube walls</p> Signup and view all the answers

    What is Meningomyelocele?

    <p>A type of neural tube defect where the spinal cord and meninges protrude through an opening in the spine.</p> Signup and view all the answers

    What is a meningocele?

    <p>A type of spina bifida where the meninges protrude through the vertebral arch.</p> Signup and view all the answers

    What is the most common neuron structure?

    <p>Multipolar</p> Signup and view all the answers

    Dorsal root ganglion and cranial ganglion are types of what kind of neurons?

    <p>Pseudounipolar</p> Signup and view all the answers

    Where are bipolar neurons typically found?

    <p>In sensory organs</p> Signup and view all the answers

    Order the collections of neurons from most defined to least defined. (nucleus, loci, substantia)

    <p>Nucleus, Loci, Substantia</p> Signup and view all the answers

    Which statement is true regarding ganglia? (select 2)

    <p>Ganglia are collections of neurons in the PNS.</p> Signup and view all the answers

    Neuroeffector junctions are connections between which two structures?

    <p>Neurons and smooth muscle cells or glands</p> Signup and view all the answers

    What is a group of axons connecting the cerebrum and brain stem called?

    <p>Capsule</p> Signup and view all the answers

    A collection of axons connecting one side of the brain to the other is called what?

    <p>Commisure</p> Signup and view all the answers

    Match the spinal cord horn with the appropriate function

    <h1>Dorsal = Sensory Ventral = Motor Lateral T1-L2 = Autonomic</h1> Signup and view all the answers

    What is the predominant cell type found in the brain, which constitutes about 90% of its cells?

    <p>Glial cells</p> Signup and view all the answers

    Microglia cells are similar to what type of cells?

    <p>Macrophages</p> Signup and view all the answers

    Which macroglial cells are found in the CNS? (Select all that apply)

    <p>Oligodendrocytes</p> Signup and view all the answers

    Which of the following macroglial cells are found in the peripheral nervous system (PNS)?

    <p>Schwann cells</p> Signup and view all the answers

    Which of the following glial cells are responsible for forming the myelin sheaths?

    <p>Oligodendrocytes (CNS)</p> Signup and view all the answers

    What is the function of astrocytes?

    <p>All of the above</p> Signup and view all the answers

    Ependymal cells are primarily involved in which of the following functions?

    <p>Production of cerebrospinal fluid (CSF)</p> Signup and view all the answers

    What is the function of satellite cells? (Select all that apply)

    <p>Supply nutrients to surrounding neurons</p> Signup and view all the answers

    Which type of glial cell expresses receptors that allow for chronic pain and HSV?

    <p>Satellite cells</p> Signup and view all the answers

    Match the astrocyte subtype with the appropriate matter

    <h1>fibrous = white matter protoplasmic = gray matter</h1> <p>=</p> Signup and view all the answers

    What is membrane potential?

    <p>The difference between concentration of molecules and charge across the cell membrane.</p> Signup and view all the answers

    Which of the following are the four main brain regions?

    <p>Cerebrum, Diencephalon, Brainstem, Cerebellum</p> Signup and view all the answers

    The hypothalamus, thalamus, and pineal gland are found in which brain region?

    <p>Diencephalon</p> Signup and view all the answers

    Which brain structure connects the cerebrum with the spinal cord?

    <p>Brainstem</p> Signup and view all the answers

    Which brain region coordinates autonomic functions of the peripheral nervous system?

    <p>Brainstem</p> Signup and view all the answers

    What disease is the tegmentum primarily involved in?

    <p>Parkinson's Disease</p> Signup and view all the answers

    Which cerebral cortex lobe contains the motor cortex?

    <p>Frontal lobe</p> Signup and view all the answers

    Which cerebral lobe is involved in sensation and contains the postcentral gyrus?

    <p>Parietal lobe</p> Signup and view all the answers

    Broca's area is located in the ___ and involved in ____.

    <p>Frontal lobe, speech production</p> Signup and view all the answers

    Wernicke's area is located in ____ and is involved in _____.

    <p>Temporal lobe; language comprehension</p> Signup and view all the answers

    A patient has difficulty speaking and writing within lines after a brain injury. What type of aphasia is this?

    <p>Broca's aphasia</p> Signup and view all the answers

    A patient speaks in long sentences with no meaning and no awareness of mistakes. What type of aphasia is this?

    <p>Wernicke's aphasia</p> Signup and view all the answers

    Meningeal layers from superficial to deep= DAP = dura, arachnoid, pia

    <p>True</p> Signup and view all the answers

    Which of the following are functions of the brain's ventricular system? (Select all that apply)

    <p>CSF production</p> Signup and view all the answers

    the ventricular system consists of ___ interconnected ventricles with CSF that gets replaced ___ times a day

    <p>4</p> Signup and view all the answers

    CSF is LIT AF Choroid plexus to Lateral ventricles to Intraventricular foramen to Third ventricle to cerebral Aqueduct to Fourth ventricle

    <p>True</p> Signup and view all the answers

    Where is the third ventricle located?

    <p>Between the left and right cerebral hemispheres</p> Signup and view all the answers

    What is the function of the foramen of Monroe?

    <p>Connects each lateral ventricle to the third ventricle</p> Signup and view all the answers

    After exiting the fourth ventricle, where does the cerebrospinal fluid (CSF) move to?

    <p>Foramen of Luschka (lateral apertures)</p> Signup and view all the answers

    The intraventricular foramen is also known as the ____

    <p>Foramen of Monro</p> Signup and view all the answers

    Once cerebrospinal fluid (CSF) leaves the foramen of Luschka or Magendie, where does it move to?

    <p>Subarachnoid space</p> Signup and view all the answers

    Once cerebrospinal fluid (CSF) leaves the subarachnoid space, where does it move to for reabsorption?

    <p>Superior sagittal sinus</p> Signup and view all the answers

    Where is the choroid plexus located?

    <p>In each cerebral ventricle</p> Signup and view all the answers

    What are the boundaries of the spinal cord?

    <p>From the foramen magnum to the conus medullaris</p> Signup and view all the answers

    What does the reabsorption of cerebrospinal fluid (CSF) depend on?

    <p>The pressure gradient between CSF and venous circulation</p> Signup and view all the answers

    CSF is isotonic

    <p>True</p> Signup and view all the answers

    Compared to plasma, CSF has less protein, less glucose, and a lower pH

    <p>True</p> Signup and view all the answers

    How is the balance of cerebrospinal fluid (CSF) maintained?

    <p>CSF is produced and reabsorbed at equal rates to maintain balance.</p> Signup and view all the answers

    What is the cauda equina?

    <p>A bundle of spinal nerve roots that extend past the end of the spinal cord</p> Signup and view all the answers

    What is unique about the spinal cord in the thoracic region?

    <p>It is thinner than in other regions.</p> Signup and view all the answers

    Spinal cord length < the length of the vertebral column

    <p>True</p> Signup and view all the answers

    At what vertebral levels does the spinal cord end in adults and newborns?

    <p>L1-L2 in adults, L3 in newborns</p> Signup and view all the answers

    Which meningeal layer directly adheres to the spinal cord?

    <p>Pia mater</p> Signup and view all the answers

    How does the spinal cord attach to the dura mater?

    <p>Lateral denticulate ligaments that arise from the pial folds</p> Signup and view all the answers

    Match the vertebrae with its correct region

    <p>cervical = 7 thoracic = 12 lumbar and sacral = 5 coccygeal = 4</p> Signup and view all the answers

    What is unique about the sacral and coccygeal vertebrae?

    <p>They are fused together.</p> Signup and view all the answers

    What are the two primary curvatures in the spine?

    <p>Sacral and Thoracic</p> Signup and view all the answers

    What are the two secondary curvatures in the spine?

    <p>Cervical and Lumbar</p> Signup and view all the answers

    Which part of the nervous system are interneurons found in?

    <p>Central Nervous System</p> Signup and view all the answers

    What is a nerve?

    <p>A bundle of axons that transmits signals between the brain and body</p> Signup and view all the answers

    How many pairs of spinal nerves are there?

    <p>31 pairs</p> Signup and view all the answers

    What is the longest nerve in the human body?

    <p>Sciatic nerve</p> Signup and view all the answers

    Match the spinal nerve with the correct number

    <p>cervical = 8 thoracic = 12 sacral = 5 coccygeal = 1</p> Signup and view all the answers

    Why are injuries in the CNS more devastating than injuries in the PNS?

    <p>CNS has minimal axonal regeneration</p> Signup and view all the answers

    What are the functions of the enteric nervous system? (Select all that apply)

    <p>Regulates gastrointestinal motility</p> Signup and view all the answers

    What is the threshold potential for a neuron?

    <p>-55 mV</p> Signup and view all the answers

    What is the site of cerebrospinal fluid (CSF) absorption?

    <p>Arachnoid granulations (villi)</p> Signup and view all the answers

    Where is the blood-brain barrier (BBB) absent? (Select all that apply)

    <p>Choroid plexus</p> Signup and view all the answers

    As cerebral blood flow increases, which of the following also increases?

    <p>Cerebral metabolic rate of oxygen (CMRO2)</p> Signup and view all the answers

    Which inhaled anesthetic is the only one that increases cerebral metabolic rate of oxygen (CMRO2)?

    <p>Nitrous Oxide</p> Signup and view all the answers

    How are cerebral blood flow (CBF) and arterial carbon dioxide tension (PaCO2) related?

    <p>CBF is directly proportional to PaCO2</p> Signup and view all the answers

    Volatile anesthetics uncouple cerebral blood flow (CBF) from cerebral metabolic rate of oxygen (CMRO2), meaning that ____.

    <p>They increase CBF despite decreasing metabolism.</p> Signup and view all the answers

    What is the range of cerebral autoregulation in terms of cerebral perfusion pressure (CPP)?

    <p>50-150 mmHg</p> Signup and view all the answers

    Outside of the limits of cerebral autoregulation, what is cerebral perfusion dependent on?

    <p>Arterial blood pressure</p> Signup and view all the answers

    How does cerebral blood flow (CBF) respond to changes in arterial oxygen partial pressure (PaO2)?

    <p>CBF increases as PaO2 decreases below 50-60mmHg</p> Signup and view all the answers

    Study Notes

    Neuromuscular Junction (NMJ)

    • NMJ is the synapse between a motor neuron and a skeletal muscle fiber.
    • Composed of three key components: presynaptic terminal, synaptic cleft, and postsynaptic membrane (muscle cell membrane).

    Calcium Storage in Myocyte

    • High concentrations of calcium are stored in the sarcoplasmic reticulum (SR) of myocytes.

    Sarcoplasmic Reticulum (SR)

    • The SR stores and releases calcium ions necessary for muscle contraction.

    T Tubules Function

    • T tubules assist in transmitting the action potential deep into the muscle fiber, ensuring synchronous contraction.

    Dihydropyridine (DHPR) and Ryanodine Receptors

    • DHPR serves as a voltage sensor, while ryanodine receptors mediate calcium release from the SR during muscle contraction.

    Nicotinic Acetylcholine (ACh) Receptors

    • Nicotinic ACh receptors are ligand-gated ion channels.
    • Fetal nicotinic receptors are termed extrajunctional because they appear outside the NMJ.

    Fetal Nicotinic Receptor Dynamics

    • Fetal nicotinic receptors typically disappear postnatally.

    Muscarinic Acetylcholine Receptors (mAChRs)

    • mAChRs are G protein-coupled receptors that mediate various physiological roles, including heart rate regulation and smooth muscle contraction.

    Positive Effects of Fetal Nicotinic Receptors

    • They can enhance muscle function post-denervation, aiding in recovery.

    Pre-Junctional Acetylcholine Receptors

    • Located on the presynaptic terminal, with roles in modulating neurotransmitter release.

    Post-Junctional ACh Receptors

    • They are directly involved in muscle contraction upon binding with ACh from the presynaptic neuron.

    Upregulation of Extra-Junctional Receptors

    • Typically occurs due to muscle damage or denervation, leading to an increased number of receptors on the muscle fiber surface.

    Fetal Acetylcholine Receptors Sensitivity

    • Fetal receptors have a higher sensitivity to ACh due to their distinct structural properties.
    • Myasthenia gravis is a concern when immature AChRs are upregulated.

    Resting Membrane Potential

    • The typical resting membrane potential of a neuron is around -70 mV.

    Na-K Pump Activity

    • The Na-K pump moves sodium (Na+) out of the cell and potassium (K+) into the cell, maintaining cellular excitability.

    Axolemma

    • The axolemma is the membrane that surrounds the axon of a neuron.

    Calcium Influx through Voltage-Gated Channels

    • Calcium influx triggers synaptic vesicles to fuse with the presynaptic membrane, leading to neurotransmitter release.

    Action Potentials

    • Action potentials are described as "all or none" responses, meaning they either occur fully or not at all.

    Muscle Cell Refractory Period

    • Cardiac muscle cells typically have a longer refractory period compared to skeletal muscle cells.

    Primary Excitatory Neurotransmitter in CNS

    • Glutamate is the primary excitatory neurotransmitter in the central nervous system.

    Excitatory Responses to Glutamate

    • Excitatory responses include learning, memory, and synaptic plasticity.

    Glutamate Synthesis

    • Glutamate is synthesized in the brain as it does not cross the blood-brain barrier (BBB).

    Glial Cells

    • Glial cells are support cells in the nervous system; they outnumber neurons and maintain homeostasis.

    Primary Inhibitory Neurotransmitters

    • GABA is the primary inhibitory neurotransmitter in the brain, while glycine serves this role in the spinal cord and lower brainstem.

    Glycine Formation

    • Glycine is synthesized from serine through the action of serine hydroxymethyltransferase.

    NMDA Receptor Co-activators

    • Co-activators include glycine and D-serine, enhancing NMDA receptor function.

    Endogenous Opioid-like Substances

    • Endorphins, enkephalins, and dynorphins are associated with opioid-like activity.

    Substance P in CNS

    • Substance P is primarily found in various regions of the brain and is associated with pain transmission and inflammatory responses.

    Unconventional Neurotransmitters

    • They can send retrograde signals from postsynaptic to presynaptic neurons and are not stored in traditional synaptic vesicles.

    Gasotransmitters

    • Examples include nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S).

    Cannabinoid Receptors

    • CB1 receptors are mainly responsible for the "high," while CB2 receptors are linked to immune system functions without psychoactive effects.

    Endogenous Cannabinoids

    • The body produces endocannabinoids, similar to compounds found in cannabis.

    Development in Utero

    • The nervous system is the first to develop during fetal life and the last to mature.

    Ventricular System

    • Comprises interconnected ventricles, with cerebrospinal fluid (CSF) being replenished multiple times daily.

    CSF Pathway

    • CSF flows from the choroid plexus to the lateral ventricles, through the intraventricular foramen to the third ventricle, and down through the cerebral aqueduct to the fourth ventricle.

    Third Ventricular Location

    • Situated centrally between the two halves of the thalamus.

    Foramen of Monroe Function

    • Connects lateral ventricles to the third ventricle.

    Reabsorption of CSF

    • Occurs in the superior sagittal sinus after leaving the subarachnoid space.

    Choroid Plexus Location

    • Found within the ventricles of the brain, where CSF is produced.

    Spinal Cord Boundaries

    • Extends from the brainstem to the conus medullaris, approximately at L1-L2 in adults.

    Unique Features of Thoracic Spinal Cord

    • Contains the intermediolateral cell column, playing a role in autonomic functions.

    Spinal Cord Length Comparison

    • The spinal cord is shorter than the vertebral column; it ends at different vertebral levels in adults (L1-L2) and newborns (L3).

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    NMJ, NT, action potentials, neurons, glial cells, cerebral hemispheres, and brain A&P

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