Neuroscience: Synapses and Communication
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Questions and Answers

What is the primary function of a synapse?

  • Transmission of impulses between neurons (correct)
  • Direct contact communication
  • Release of hormones into the bloodstream
  • Neighboring cell communication

    • Endocrine communication involves the release of neurotransmitters.

    False

    What occurs in the synaptic cleft?

    Neurotransmitter release and reception.

    In synaptic communication, nerve cells release __________ which bind to receptors on nearby cells.

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

    Which type of cellular communication affects neighboring cells?

    <p>Paracrine communication</p> Signup and view all the answers

    Match the following mechanisms of cellular communication with their descriptions:

    <p>Direct contact = Molecules on the surface of one cell recognized by an adjacent cell Paracrine communication = Signaling to nearby cells Endocrine communication = Hormones affecting distant cells Synaptic communication = Nerve cells releasing neurotransmitters</p> Signup and view all the answers

    Synaptic knobs contain synaptic vesicles filled with neurotransmitters.

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

    What is the term for the 'swollen' end of an axon at a synapse?

    <p>Synaptic knob or end bulb.</p> Signup and view all the answers

    What is the primary role of neurotransmitters in the nervous system?

    <p>To transmit impulses between neurons</p> Signup and view all the answers

    The opening of sodium channels during synaptic transmission always guarantees an action potential will occur.

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

    What causes synaptic vesicles to move toward the synaptic cleft?

    <p>Calcium entering the end bulb.</p> Signup and view all the answers

    Neurotransmitter molecules diffuse across the __________ and bind to receptor sites.

    <p>synaptic cleft</p> Signup and view all the answers

    Match the following terms with their descriptions:

    <p>Neurotransmitter = Chemical that transmits signals across a synapse Action potential = Electrical impulse that travels along a neuron Synaptic vesicle = Container for neurotransmitters Sodium channel = Channel that allows sodium ions to enter the neuron</p> Signup and view all the answers

    What happens if the neurotransmitter released is insufficient?

    <p>The membrane potential will never reach the threshold</p> Signup and view all the answers

    One neuron can possess thousands of ion channels and pumps.

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

    The release of neurotransmitters occurs through a process known as __________.

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

    Which cranial nerve is classified as both sensory and motor?

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

    The olfactory nerve is classified as a motor cranial nerve.

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

    What is the primary function of the oculomotor nerve?

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

    The _____ nerve is responsible for hearing and balance.

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

    Match the cranial nerves with their classification:

    <p>I Olfactory nerve = Sensory III Oculomotor nerve = Motor V Trigeminal nerve = Mixed VII Facial nerve = Mixed</p> Signup and view all the answers

    Which neurotransmitter is primarily associated with the fight-or-flight response?

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

    Dopamine is linked to both Parkinson's disease and schizophrenia.

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

    What do gyri refer to in the brain?

    <p>Elevated ridges winding around the brain</p> Signup and view all the answers

    The terminal portion of the spinal cord is known as the ______.

    <p>conus medullaris</p> Signup and view all the answers

    Match the parts of the brain with their respective functions:

    <p>Cerebrum = Higher cognitive functions Cerebellum = Coordination and balance Brain Stem = Regulates vital functions Diencephalon = Processes sensory information</p> Signup and view all the answers

    What are the three layers of meninges that cover the brain and spinal cord?

    <p>Pia Mater, Arachnoid Mater, Dura Mater</p> Signup and view all the answers

    The central sulcus divides the frontal lobe from the temporal lobe.

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

    The collection of nerve roots at the inferior end of the vertebral canal is known as the ______.

    <p>cauda equina</p> Signup and view all the answers

    How many pairs of spinal nerves are there in the human body?

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

    Which part of the brain is responsible for coordination and balance?

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

    Which cranial nerve is responsible for smell?

    <p>Olfactory (CN I)</p> Signup and view all the answers

    The abducent nerve (CN VI) is responsible for motor function to the superior oblique muscle of the eye.

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

    What is the main action of the glossopharyngeal nerve (CN IX)?

    <p>Motor to stylopharyngeus muscle; assists with swallowing.</p> Signup and view all the answers

    The __________ nerve is responsible for hearing.

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

    Match the cranial nerve with its main action:

    <p>Oculomotor (CN III) = Movement of eye muscles and pupil constriction Facial (CN VII) = Muscles of facial expression Trigeminal (CN V) = Sensation from face and motor to mastication Vagus (CN X) = Parasympathetic control of the heart and digestive tract</p> Signup and view all the answers

    Which cranial nerve exits via the jugular foramen?

    <p>Vagus (CN X)</p> Signup and view all the answers

    The trochlear nerve (CN IV) is categorized as a special sensory nerve.

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

    Name the cranial nerve responsible for taste sensation from the anterior two-thirds of the tongue.

    <p>Facial (CN VII)</p> Signup and view all the answers

    The __________ nerve provides motor innervation to the lateral rectus muscle of the eye.

    <p>Abducent (CN VI)</p> Signup and view all the answers

    Match the nerve with its origin:

    <p>Glossopharyngeal (CN IX) = Medulla Oculomotor (CN III) = Midbrain Hypoglossal (CN XII) = Medulla Optic (CN II) = Retina</p> Signup and view all the answers

    What is the primary function of the accessory nerve (CN XI)?

    <p>Motor to the sternocleidomastoid and trapezius muscles</p> Signup and view all the answers

    The optic nerve (CN II) is responsible for transmitting visual information from the retina.

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

    What type of nerve is the oculomotor nerve classified as?

    <p>Somatic and visceral motor</p> Signup and view all the answers

    The __________ nerve transmits equilibrium information from the inner ear.

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

    Study Notes

    Synapses

    • Synapse is the point of impulse transmission between neurons
    • The synapse is a functional connection between the axon terminal (synaptic knob) of the presynaptic neuron and the dendrite of the postsynaptic neuron
    • In the synapse, action potential is transmitted across the membrane
    • The impulse transmission across the synapse involves the release of neurotransmitters
    • Synaptic vesicles contain neurotransmitters

    Cellular Communication

    • Direct contact communication: molecules on the surface of one cell are recognized by receptors on the adjacent cell
    • Paracrine communication: signal released from a cell has an effect on neighboring cells
    • Endocrine communication: hormones released from a cell affect other cells throughout the body
    • Synaptic communication: nerve cells release the signal (neurotransmitter) which binds to receptors on nearby cells
    • Membrane Potential: the electrical gradient across a cell membrane

    Neurotransmitters

    • Acetylcholine: transmits signal to skeletal muscle
    • Epinephrine (adrenaline) & norepinephrine: fight-or-flight response
    • Dopamine: affects sleep, mood, attention & learning, lack of dopamine in the brain is associated with Parkinson's disease, excessive dopamine linked to schizophrenia
    • Serotonin: affects sleep, mood, attention & learning

    The Brain

    • The brain is composed of four parts: cerebrum, diencephalon, brainstem, and cerebellum
    • The brainstem is made up of midbrain, pons, and medulla
    • The brain contains gray matter surrounded by white matter, with an outer cortex of gray matter

    Meninges

    • Meninges are three membranes around the brain and spinal cord
    • Meninges provide protection and cover the CNS
    • The Meninges are made of connective tissue and enclose and protect blood vessels supplying CNS
    • Meninges contain CSF
    • The three layers of meninges are: dura mater, arachnoid mater, and pia mater

    Cerebral Features

    • Gyri: elevated ridges "winding" around the brain
    • Sulci: small grooves dividing the gyri
    • Fissures: deep grooves, generally dividing large regions/lobes of the brain. Examples include the longitudinal fissure, transverse fissure, and sylvian/lateral fissure

    Gross Anatomy of the Spinal Cord

    • The spinal cord extends from C1 to L1/2
    • The spinal cord is covered by three layers of meninges
    • The spinal cord terminates at L1/2 (conus medullaris)
    • The spinal cord is surrounded by CSF in the subarachnoid space
    • The spinal cord has 31 pairs of spinal nerves
    • The spinal cord has cervical and lumbar enlargements
    • The spinal cord has a cauda equina, which is a collection of nerve roots at the inferior end of the vertebral canal

    Meningeal Layers

    • The three meningeal layers are: dura mater, arachnoid mater, and pia mater

    Membranes Covering the CNS

    • The membranes covering the CNS are protective coverings
    • The limiting membrane has two layers: epipial and intima pia
    • The epipial layer is made of collagenous fibers and is absent on the convexity of the brain
    • The intima pia is the inner membranous layer, following the brain contour, it is avascular, contains perivascular space, and is made of reticular and elastic fibers
    • Cerebral vessels lie on the surface of intima within the subarachnoid space

    Cranial Nerves

    • There are 12 pairs of cranial nerves
    • Cranial Nerves: I, II, III, IV, V, VI, VII, VIII, IX, X, XI, and XII
    • Sensory cranial nerves: contain only afferent (sensory) fibers
    • Motor cranial nerves: contain only efferent (motor) fibers
    • Mixed nerves: contain both sensory and motor fibers

    Cranial Nerves

    • Twelve pairs of cranial nerves emerge from the brain and travel through foramina in the skull to organs and structures of the head, neck, and trunk.
    • Sensory (Afferent) nerves carry impulses from sensory receptors to the brain.
    • Motor (Efferent) nerves carry impulses from the brain to muscles and glands.
    • Mixed nerves contain both sensory and motor fibers.

    Sensory Cranial Nerves

    • Olfactory nerve (CN I):
      • Responsible for smell.
      • Sensory fibers originate in the olfactory epithelium of the nasal cavity and travel through the cribriform plate of the ethmoid bone to the olfactory bulb.
    • Optic nerve (CN II):
      • Responsible for vision.
      • Sensory fibers originate in the retina of the eye and travel through the optic canal to the lateral geniculate nucleus of the thalamus.
    • Vestibulocochlear nerve (CN VIII):
      • Responsible for hearing and balance.
      • Sensory fibers for hearing originate in the spiral organ (organ of Corti) of the cochlea and travel through the internal acoustic meatus to the cochlear nuclei of the brainstem.
      • Sensory fibers for balance originate in the semicircular ducts, utricle, and saccule of the inner ear and travel through the internal acoustic meatus to the vestibular nuclei of the brainstem.

    Motor Cranial Nerves

    • Oculomotor nerve (CN III):
      • Somatic motor function: Controls four of the six extrinsic eye muscles (superior rectus, inferior rectus, medial rectus, and inferior oblique), as well as the levator palpebrae superioris muscle (raises eyelid).
      • Visceral motor function: Controls the sphincter pupillae muscle (constricts pupil) and the ciliary muscle (accommodates the lens of the eye).
    • Trochlear nerve (CN IV):
      • Controls the superior oblique muscle, which assists in turning the eye inferolaterally.
    • Abducent nerve (CN VI):
      • Controls the lateral rectus muscle, which turns the eye laterally.
    • Accessory nerve (CN XI):
      • Controls the sternocleidomastoid and trapezius muscles.
    • Hypoglossal nerve (CN XII):
      • Controls the intrinsic and extrinsic muscles of the tongue.

    Mixed Cranial Nerves

    • Trigeminal nerve (CN V):
      • Ophthalmic nerve (CN V1): Sensory fibers from the cornea, skin of the forehead, scalp, eyelids, nose, and mucosa of the nasal cavity and paranasal sinuses.
      • Maxillary nerve (CN V2): Sensory fibers from the skin of the face over the maxilla, including the upper lip, maxillary teeth, mucosa of the nose, maxillary sinuses, and palate.
      • Mandibular nerve (CN V3): Sensory fibers from the skin and side of the head, mandible including lower lip, mandibular teeth, temporomandibular joint, mucosa of the mouth, and anterior two-thirds of the tongue. Motor fibers to muscles of mastication, mylohyoid, anterior belly of digastric, tensor veli palatini, and tensor tympani.
    • Facial nerve (CN VII):
      • Branchial motor function: Controls the muscles of facial expression, scalp, stapedius of the middle ear, stylohyoid, and posterior belly of the digastric.
      • Special sensory function: Taste from the anterior two-thirds of the tongue and the palate.
      • Visceral motor function: Controls the submandibular and sublingual salivary glands, lacrimal gland, and glands of the nose and palate.
    • Glossopharyngeal nerve (CN IX):
      • Branchial motor function: Controls the stylopharyngeus muscle to assist with swallowing.
      • Visceral motor function: Controls the parotid gland.
      • Visceral sensory function: Sensation from the parotid gland, carotid body and sinus, pharynx, and middle ear.
      • Special sensory function: Taste from the posterior third of the tongue.
      • General sensory function: Cutaneous sensation from the external ear.
    • Vagus nerve (CN X):
      • Branchial motor function: Controls the constrictor muscles of the pharynx, intrinsic muscles of the larynx, muscles of the palate, and the striated muscle in the superior two-thirds of the esophagus.
      • Visceral motor function: Controls the smooth muscle of the trachea, bronchi, digestive tract, and cardiac muscle of the heart.
      • Visceral sensory function: Sensation from the base of the tongue, pharynx, larynx, trachea, bronchi, heart, esophagus, stomach, and intestine to the left colic flexure.
      • Special sensory function: Taste from the epiglottis and palate.
      • General sensory function: Sensation from the auricle, external acoustic meatus, and dura mater of the posterior cranial fossa.

    Clinical Relevance

    • Damage to cranial nerves can lead to a variety of symptoms, depending on the nerve affected.
    • For Example: Damage to the facial nerve can cause paralysis of the facial muscles, leading to a droopy face.
    • Damage to the oculomotor nerve can cause double vision, drooping eyelid, and dilated pupil.
    • Damage to the vestibulocochlear nerve can cause hearing loss, tinnitus, and dizziness.
    • Damage to the vagus nerve can cause difficulty swallowing, speaking, or breathing.

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    Explore the intricate world of synapses and cellular communication in this quiz. Test your knowledge on neurotransmitters, types of cellular communication, and the role of synapses in transmitting impulses. Delve into critical concepts that highlight how neurons interact and communicate effectively.

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