Synapse Structure and Function
87 Questions
4 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Which of the following BEST describes the cauda equina?

  • A bundle of nerve roots extending from the spinal cord below the end of the spinal cord. (correct)
  • A group of motor neurons in the lateral gray horn of the spinal cord that control smooth muscle, heart muscle, and glands.
  • A collection of myelinated axons in the white matter of the spinal cord.
  • A large collection of sensory neurons in the posterior gray horn of the spinal cord.

Damage to the posterior gray horns of the spinal cord would MOST LIKELY affect which of the following?

  • Sensory perception. (correct)
  • Motor control of skeletal muscles.
  • Communication between the left and right sides of the spinal cord.
  • Control of visceral organs.

Which of the following statements accurately describes the relationship between the spinal cord and the vertebrae?

  • The spinal cord extends only to the level of the first lumbar vertebrae, and the vertebrae protect the spinal cord only up to that level. (correct)
  • The spinal cord extends to the level of the first or second lumbar vertebrae, and the vertebrae protect the spinal cord up to the level of the sacrum.
  • The spinal cord extends to the level of the first or second lumbar vertebrae, and the vertebrae protect the spinal cord throughout its length.
  • The spinal cord extends to the tip of the spinal column, and the vertebrae protect the spinal cord throughout its length.

Which of the following BEST describes the function of the gray commissure in the spinal cord?

<p>To connect the gray matter on one side of the spinal cord to the gray matter on the other side. (D)</p> Signup and view all the answers

Which of the following structures contains the cell bodies of the neurons that control skeletal muscle movement?

<p>Anterior gray horn (C)</p> Signup and view all the answers

Which of the following is a CORRECT statement about the white matter of the spinal cord?

<p>It contains both myelinated and unmyelinated axons. (B)</p> Signup and view all the answers

What is the function of the ascending tracts in the spinal cord?

<p>To carry sensory information from the spinal cord to the brain. (B)</p> Signup and view all the answers

Which of the following statements accurately describes the function of the anterior white columns in the spinal cord?

<p>To connect the anterior gray horns to the anterior median fissure. (D)</p> Signup and view all the answers

What is the most common symptom of encephalitis?

<p>Headache (A)</p> Signup and view all the answers

Which of the following is NOT a common causative virus in AIDS patients with encephalitis?

<p>St. Louis encephalitis virus (A)</p> Signup and view all the answers

What causes the characteristic spongiform appearance of the brain in prion diseases?

<p>Formation of large vacuoles in the cortex and cerebellum (B)</p> Signup and view all the answers

What is the primary mode of transmission for bovine spongiform encephalopathy (BSE)?

<p>Cattle feed containing infected animal byproducts (C)</p> Signup and view all the answers

Which of the following is NOT a symptom of Creutzfeldt-Jakob disease (CJD)?

<p>High fever (A)</p> Signup and view all the answers

What is the characteristic symptom of fatal familial insomnia (FFI)?

<p>Untreatable insomnia (D)</p> Signup and view all the answers

What caused the decline in the incidence of kuru in the Fore highlands of New Guinea?

<p>Government efforts to curtail cannibalism (C)</p> Signup and view all the answers

What is the primary function of the cervical enlargement of the spinal cord?

<p>Supply nerves to the shoulder girdles and upper limbs (D)</p> Signup and view all the answers

What is the function of the dorsal root ganglia?

<p>Contain the cell bodies of sensory neurons (C)</p> Signup and view all the answers

What type of nerves are spinal nerves classified as?

<p>Mixed nerves (A)</p> Signup and view all the answers

At what age does the spinal cord stop growing?

<p>4 years old (C)</p> Signup and view all the answers

What is the function of the slender strand of fibrous tissue that extends from the inferior tip of the spinal cord to the coccyx?

<p>To anchor the spinal cord and prevent upward movement (A)</p> Signup and view all the answers

Which of the following is NOT a part of the spinal cord anatomy?

<p>Lateral Ventricle (B)</p> Signup and view all the answers

How many spinal nerves are there in the human body?

<p>31 (A)</p> Signup and view all the answers

What happens to the dorsal and ventral roots as the vertebral column elongates after age 4?

<p>They grow longer (A)</p> Signup and view all the answers

What is the maximum width of the adult spinal cord?

<p>14 mm (A)</p> Signup and view all the answers

What is the primary function of neurotransmitters within a synapse?

<p>To transmit information between neurons or between a neuron and an effector cell. (B)</p> Signup and view all the answers

Which of the following accurately describes the direction of nerve impulse transmission across a synapse?

<p>From the presynaptic neuron to the postsynaptic neuron. (D)</p> Signup and view all the answers

What is the synaptic cleft?

<p>The space between the presynaptic and postsynaptic membranes. (D)</p> Signup and view all the answers

At a neuroglandular junction, what role does the neuron play?

<p>It controls or regulates the activity of a secretory cell. (B)</p> Signup and view all the answers

Which event directly triggers the release of neurotransmitters from the axon terminal into the synaptic cleft?

<p>The arrival of an action potential at the axon terminal. (C)</p> Signup and view all the answers

What is the function of synaptic vesicles?

<p>To store and release neurotransmitters into the synaptic cleft. (D)</p> Signup and view all the answers

What is a key characteristic of cholinergic synapses related to neurotransmitters?

<p>They release acetylcholine (ACh) as their primary neurotransmitter. (C)</p> Signup and view all the answers

How does a neurotransmitter such as acetylcholine (ACh) transmit a signal to the postsynaptic neuron?

<p>By binding to receptors on the postsynaptic membrane. (A)</p> Signup and view all the answers

What triggers the exocytosis of synaptic vesicles and release of acetylcholine (ACh) at a cholinergic synapse?

<p>Entry of calcium ions into the axon terminal. (D)</p> Signup and view all the answers

How does acetylcholinesterase (AChE) remove ACh from the synaptic cleft?

<p>By breaking down ACh into acetate and choline. (A)</p> Signup and view all the answers

What is the primary mechanism by which organophosphates exert their toxic effects?

<p>Deactivating acetylcholinesterase. (A)</p> Signup and view all the answers

Which of the following is used as an antidote to restore cholinesterase activity in organophosphate poisoning?

<p>Pralidoxime (2-PAM). (A)</p> Signup and view all the answers

What is the immediate effect of ACh binding to receptors on the postsynaptic membrane?

<p>Depolarization of the postsynaptic membrane. (D)</p> Signup and view all the answers

Which of the following neurotransmitters primarily has inhibitory effects on postsynaptic neurons?

<p>Dopamine. (A)</p> Signup and view all the answers

What is the fate of norepinephrine (NE) after it has been released into the synapse?

<p>It is broken down by monoamine oxidase. (A)</p> Signup and view all the answers

Which of the following is a symptom associated with muscarinic receptor stimulation in acute organophosphate poisoning?

<p>Increased salivation. (D)</p> Signup and view all the answers

What is the name given to synapses that release norepinephrine (NE)?

<p>Adrenergic. (A)</p> Signup and view all the answers

Which of the following events occurs first at a cholinergic synapse after the arrival of an action potential?

<p>Depolarization of the axon terminal. (B)</p> Signup and view all the answers

Which of the following symptoms is associated with nicotinic receptor stimulation at the neuromuscular junction in acute organophosphate poisoning?

<p>Muscle fasciculations. (D)</p> Signup and view all the answers

What is the effect of drugs that stimulate receptors that otherwise only respond to neurotransmitters?

<p>They can have complex effects on perception, motor control and emotional states. (A)</p> Signup and view all the answers

Which of the following neurotransmitters is also known as noradrenaline?

<p>Norepinephrine (NE). (A)</p> Signup and view all the answers

Which of the following is a route of entry for organophosphates into the body?

<p>Through the skin or respiratory tract. (A)</p> Signup and view all the answers

What is the primary effect of norepinephrine (NE) on postsynaptic neurons?

<p>An excitatory, depolarizing effect. (C)</p> Signup and view all the answers

What type of synapse uses norepinephrine as its neurotransmitter?

<p>Adrenergic synapse (D)</p> Signup and view all the answers

Which neurotransmitter is utilized in the preganglionic nerves of the sympathetic nervous system?

<p>Acetylcholine (C)</p> Signup and view all the answers

What happens when 10 excitatory synapses and 10 inhibitory synapses are active simultaneously?

<p>The effects cancel each other out (D)</p> Signup and view all the answers

How do neuronal pools interact with each other?

<p>By direct control or stimulation/depression of activity (A)</p> Signup and view all the answers

What is the primary function of the meninges?

<p>To provide support and protect the CNS (A)</p> Signup and view all the answers

Which meningeal layer is the outermost covering of the CNS?

<p>Dura mater (C)</p> Signup and view all the answers

What type of neural circuit is characterized by multiple inputs converging on a single neuron?

<p>Convergence (C)</p> Signup and view all the answers

What is characterized by the spreading of stimulation from one neuron to multiple neurons?

<p>Divergence (D)</p> Signup and view all the answers

What is one effect of blocking calcium channels at cholinergic synapses?

<p>Inhibition of action potential generation (A)</p> Signup and view all the answers

What is the role of interneurons within a neuronal pool?

<p>To provide processing and integration of sensory and motor signals (B)</p> Signup and view all the answers

What is the estimated number of interneurons in the human body?

<p>20 billion (D)</p> Signup and view all the answers

What type of neural circuits allows both voluntary and involuntary control of a motor function?

<p>Convergence (A)</p> Signup and view all the answers

Which layer of the meninges is directly adhered to the surface of the brain?

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

What is contained within the epidural space of the spinal cord?

<p>Areolar tissue, blood vessels, and adipose tissue (C)</p> Signup and view all the answers

What does an epidural block primarily affect?

<p>Only spinal nerves in the immediate area of injection (B)</p> Signup and view all the answers

What is a common cause of epidural hematomas?

<p>Laceration of an artery during blunt head trauma (C)</p> Signup and view all the answers

What separates the dura mater from the arachnoid layer?

<p>Subdural space (A)</p> Signup and view all the answers

Which sign indicates meningeal inflammation in bacterial meningitis?

<p>Kernig's sign (D)</p> Signup and view all the answers

Why is the pia mater important for the brain?

<p>It is highly vascular and supplies blood to the neural tissue. (B)</p> Signup and view all the answers

What is the significance of cerebrospinal fluid (CSF) in the subarachnoid space?

<p>It acts as a shock absorber and transports nutrients. (D)</p> Signup and view all the answers

Which symptoms are commonly associated with meningitis?

<p>Altered mental status, fever, headache, and stiff neck (D)</p> Signup and view all the answers

What happens if blood accumulates in the epidural space?

<p>It leads to an epidural hematoma. (B)</p> Signup and view all the answers

What layer firmly binds to the nervous tissue of the brain?

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

How does blood pressure impact epidural versus subdural hemorrhages?

<p>Higher arterial blood pressure can cause more rapid distortion of neural tissue. (A)</p> Signup and view all the answers

What condition occurs when blood enters the space between the dura mater and the skull?

<p>Epidural hemorrhage (A)</p> Signup and view all the answers

What is the function of arachnoid layer's lymphatic fluid?

<p>It reduces friction between the dura and arachnoid layers. (D)</p> Signup and view all the answers

What is the primary purpose of a lumbar puncture?

<p>To measure cerebrospinal fluid (CSF) pressure (A)</p> Signup and view all the answers

Which of the following is a common organism causing bacterial meningitis in adults?

<p>Neisseria meningitidis (D)</p> Signup and view all the answers

Which symptom is typically associated with viral meningitis but not bacterial meningitis?

<p>Presence of white blood cells (D)</p> Signup and view all the answers

What is a notable difference between viral and bacterial meningitis regarding treatment?

<p>Bacterial meningitis requires the use of antibiotics (C)</p> Signup and view all the answers

Which organism is known to cause opportunistic infections leading to meningitis in immunocompromised patients?

<p>Candida species (B)</p> Signup and view all the answers

What finding in cerebrospinal fluid indicates bacterial meningitis?

<p>Cloudy fluid with high protein concentration (D)</p> Signup and view all the answers

Which type of meningitis is commonly referred to as aseptic meningitis?

<p>Viral meningitis (A)</p> Signup and view all the answers

What is a potential cause of tubercular meningitis?

<p>Tuberculosis infection in the lungs (C)</p> Signup and view all the answers

What is the typical initial symptom of encephalitis?

<p>Severe headache (B)</p> Signup and view all the answers

Which method is often required for the diagnosis of cysticercosis?

<p>Computed tomographic scan (D)</p> Signup and view all the answers

What is a common treatment for brain abscesses?

<p>Surgical drainage (C)</p> Signup and view all the answers

Which organism is primarily responsible for causing meningiococcemia?

<p>Neisseria meningitidis (A)</p> Signup and view all the answers

What complication can arise from Naegleria fowleri infection?

<p>Acute meningoencephalitis (B)</p> Signup and view all the answers

What is a key characteristic of fungal meningitis?

<p>Tendency to be chronic and hard to treat (A)</p> Signup and view all the answers

Flashcards

Synapse

A junction between a neuron and another cell, where communication occurs through the release of neurotransmitters.

Presynaptic neuron

The neuron that sends a signal at a synapse, releasing neurotransmitters.

Postsynaptic neuron

The neuron that receives a signal at a synapse, with receptors for neurotransmitters.

Synaptic cleft

A small gap between the presynaptic and postsynaptic neurons at a synapse.

Signup and view all the flashcards

Neurotransmitters

Chemical messengers released from the presynaptic neuron that travel across the synaptic cleft to bind with receptors on the postsynaptic neuron.

Signup and view all the flashcards

Neuromuscular junction

A synapse between a neuron and a muscle cell.

Signup and view all the flashcards

Neuroglandular junction

A synapse between a neuron and a secretory cell.

Signup and view all the flashcards

Neuron-neuron synapse

A synapse where a neuron communicates with another neuron.

Signup and view all the flashcards

Cholinergic Synapse

A synapse that uses acetylcholine as the neurotransmitter.

Signup and view all the flashcards

Adrenergic Synapse

A synapse that uses norepinephrine as the neurotransmitter.

Signup and view all the flashcards

Neuronal Pool

A group of interconnected interneurons with a specific function within the CNS.

Signup and view all the flashcards

Divergence

The spread of information from one neuron to multiple neurons or neuronal pools.

Signup and view all the flashcards

Convergence

The convergence of input from multiple neurons onto a single postsynaptic neuron.

Signup and view all the flashcards

Excitatory Neurotransmitter

A neurotransmitter that causes depolarization of the postsynaptic membrane, making the neuron more likely to fire an action potential.

Signup and view all the flashcards

Inhibitory Neurotransmitter

A neurotransmitter that causes hyperpolarization of the postsynaptic membrane, making the neuron less likely to fire an action potential.

Signup and view all the flashcards

Excitatory/Inhibitory Balance

The balance between excitatory and inhibitory neurotransmitters that determines whether a neuron will fire an action potential.

Signup and view all the flashcards

Dura Mater

The outermost layer of the meninges, a tough fibrous membrane that surrounds the brain and spinal cord.

Signup and view all the flashcards

Arachnoid Mater

The middle layer of the meninges, a delicate, web-like membrane that lies beneath the dura mater.

Signup and view all the flashcards

Pia Mater

The innermost layer of the meninges, a thin, vascular membrane that tightly adheres to the surface of the brain and spinal cord.

Signup and view all the flashcards

Meninges

The three layers of specialized membranes surrounding the brain and spinal cord.

Signup and view all the flashcards

Acetylcholine (ACh)

A neurotransmitter that plays a crucial role in muscle contraction, memory, and learning.

Signup and view all the flashcards

Dural Fold

A folded membranous sheet formed by the inner layer of the dura mater, which helps to hold the brain in position.

Signup and view all the flashcards

Exocytosis

The process of releasing neurotransmitters from the presynaptic neuron into the synaptic cleft.

Signup and view all the flashcards

Dural Sinuses

Large collecting veins located between the two layers of a dural fold, draining blood from the brain.

Signup and view all the flashcards

Acetylcholinesterase (AChE)

An enzyme that breaks down acetylcholine in the synaptic cleft, terminating its action.

Signup and view all the flashcards

Serotonin

A neurotransmitter that plays a role in mood, sleep, appetite, and learning.

Signup and view all the flashcards

Drugs

Chemicals that influence the activity of neurotransmitters.

Signup and view all the flashcards

Dopamine

One of the major neurotransmitters involved in reward, movement, and attention. Excess dopamine is associated with schizophrenia.

Signup and view all the flashcards

Gamma-Aminobutyric Acid (GABA)

A neurotransmitter that plays a role in inhibiting neuronal activity in the central nervous system.

Signup and view all the flashcards

Norepinephrine (NE)

The primary neurotransmitter of the sympathetic nervous system, involved in stress response, arousal, and attention.

Signup and view all the flashcards

Depolarization

A state where a neuron is more likely to fire an action potential.

Signup and view all the flashcards

Organophosphates

A class of insecticides that inhibit the enzyme acetylcholinesterase, leading to an accumulation of acetylcholine.

Signup and view all the flashcards

Atropine

A drug used to treat organophosphate poisoning by competing with acetylcholine for its receptors.

Signup and view all the flashcards

Pralidoxime (2-PAM)

A medicine that reactivates acetylcholinesterase activity, reversing the effects of organophosphate poisoning.

Signup and view all the flashcards

Hyperpolarization

A state where a neuron is less likely to fire an action potential.

Signup and view all the flashcards

Cauda Equina

The collection of nerve roots extending from the spinal cord below the level of L1-L2. This resembles a horse's tail due to the long nerve roots.

Signup and view all the flashcards

Gray Matter in Spinal Cord

The gray matter of the spinal cord forms an H-shaped structure. It contains the cell bodies of neurons and glial cells.

Signup and view all the flashcards

White Matter in Spinal Cord

The white matter of the spinal cord is primarily composed of myelinated and unmyelinated axons.

Signup and view all the flashcards

Posterior Gray Horns

The posterior gray horns of the spinal cord contain sensory nuclei, which receive and process sensory information.

Signup and view all the flashcards

Anterior Gray Horns

The anterior gray horns of the spinal cord contain motor nuclei, which control the movement of skeletal muscles.

Signup and view all the flashcards

Lateral Gray Horns

The lateral gray horns of the spinal cord contain visceral motor neurons, which control the function of smooth muscle, cardiac muscle, and glands.

Signup and view all the flashcards

Gray Commissure

The gray commissure located anterior and posterior to the central canal connects the gray matter of the spinal cord from left to right.

Signup and view all the flashcards

White Commissure

The white commissure located anterior to the central canal connects the white matter of the spinal cord from left to right.

Signup and view all the flashcards

Meningitis

Inflammation of the membranes surrounding the brain and spinal cord.

Signup and view all the flashcards

Lumbar Puncture

A procedure to withdraw cerebrospinal fluid (CSF) from the subarachnoid space, usually between the third and fourth lumbar vertebrae.

Signup and view all the flashcards

Cerebrospinal Fluid (CSF)

A clear fluid that surrounds the brain and spinal cord, providing cushioning and protection.

Signup and view all the flashcards

Bacterial Meningitis

A serious infection of the meninges, often caused by bacteria.

Signup and view all the flashcards

Encephalitis

An inflammatory condition of the brain, typically caused by viruses.

Signup and view all the flashcards

Aseptic Meningitis

A type of meningitis caused by viruses, where the infectious organism cannot be identified.

Signup and view all the flashcards

Brain Abscess

A collection of pus within the brain or spinal cord.

Signup and view all the flashcards

CNS Infection

An infection that affects the central nervous system and can be caused by a variety of factors including viruses, bacteria, and fungi.

Signup and view all the flashcards

Cysticercosis

Parasitic cysts that can lodge in various tissues, including the brain, causing symptoms like seizures and hydrocephalus.

Signup and view all the flashcards

Hydrocephalus

A condition characterized by an increase in intracranial pressure due to the accumulation of fluid in the brain.

Signup and view all the flashcards

Toxoplasma gondii

A common parasite that can cause brain abscesses, particularly in AIDS patients and those with weakened immune systems.

Signup and view all the flashcards

Meningismus

A condition characterized by headache, fever, nausea, and stiff neck, often indicating an underlying infection like meningitis.

Signup and view all the flashcards

Meningiococcemia

Meningitis caused by the bacteria Neisseria meningitidis, which can lead to a severe and life-threatening infection.

Signup and view all the flashcards

Naegleria Infection

An infection caused by free-living amoebas, often found in water sources, that can invade the nervous system and be fatal.

Signup and view all the flashcards

Epidural space

A space between the dura mater of the spinal cord and the vertebral canal, containing loose connective tissue, blood vessels, and fat.

Signup and view all the flashcards

Epidural block

A procedure where an anesthetic drug is injected into the epidural space to temporarily block sensory and motor nerve signals, often used for pain management during childbirth.

Signup and view all the flashcards

Epidural hematoma

A serious condition where blood collects in the epidural space due to bleeding from a damaged artery, usually from head trauma, causing pressure on the brain.

Signup and view all the flashcards

Subdural space

A narrow space between the dura mater and the arachnoid, containing a small amount of fluid to reduce friction.

Signup and view all the flashcards

Subarachnoid space

The space between the arachnoid and the pia mater, filled with cerebrospinal fluid (CSF).

Signup and view all the flashcards

Subdural hemorrhage

A serious condition where blood collects in the subdural space due to bleeding from a damaged blood vessel, usually from head trauma, causing pressure on the brain.

Signup and view all the flashcards

Streptococcal pneumoniae

The primary organism responsible for bacterial meningitis, an important bacterial species that can cause respiratory infections.

Signup and view all the flashcards

Haemophilus influenzae (type b)

A type of bacteria that can cause bacterial meningitis, particularly among infants and children.

Signup and view all the flashcards

Neisseria meningitidis

A type of bacteria that can cause bacterial meningitis, usually spread through respiratory droplets.

Signup and view all the flashcards

Brudzinski's sign

A sign of meningitis characterized by stiffness in the neck accompanied by flexion of the hips and knees when the neck is passively flexed.

Signup and view all the flashcards

Kernig's sign

A sign of meningitis characterized by an inability to extend the legs when the knees are flexed.

Signup and view all the flashcards

Epidemic Encephalitis

A type of encephalitis caused by Western equine encephalitis virus, St. Louis encephalitis virus, or California encephalitis virus.

Signup and view all the flashcards

Prion

A protein that can cause disease. Prions are unusual because they don’t contain DNA or RNA.

Signup and view all the flashcards

Spongiform Encephalopathy

A brain disease caused by prions. It leads to holes in the brain, like a sponge.

Signup and view all the flashcards

Bovine Spongiform Encephalopathy (BSE)

A fatal prion disease that affects cattle. It is also known as Mad Cow Disease.

Signup and view all the flashcards

Creutzfeldt-Jakob Disease (CJD)

A fatal prion disease in humans. Symptoms progress rapidly, leading to dementia, jerking movements, and death.

Signup and view all the flashcards

Fatal Familial Insomnia (FFI)

A rare prion disease that causes insomnia, nervous system dysfunction, and death.

Signup and view all the flashcards

Kuru

A prion disease that was found in members of the Fore tribe in New Guinea. It was spread through a traditional ritual where people ate the brains of dead relatives.

Signup and view all the flashcards

Cervical Enlargement

The thicker part of the spinal cord that provides nerves to the shoulders and upper limbs.

Signup and view all the flashcards

Lumbar Enlargement

The thicker part of the spinal cord that provides nerves to the pelvis and lower limbs.

Signup and view all the flashcards

Filum Terminale

A slender strand of fibrous tissue that extends from the end of the spinal cord to the coccyx. It anchors the spinal cord and prevents it from moving upwards.

Signup and view all the flashcards

Central Canal

A narrow passageway filled with cerebrospinal fluid (CSF) in the center of the spinal cord.

Signup and view all the flashcards

Posterior Median Sulcus

A groove on the posterior surface of the spinal cord.

Signup and view all the flashcards

Anterior Median Fissure

A deeper groove on the anterior surface of the spinal cord.

Signup and view all the flashcards

Spinal Segments

Segments of the spinal cord that give rise to spinal nerves.

Signup and view all the flashcards

Study Notes

Synapse Structure and Function

  • A synapse is a site where a neuron communicates with another cell (neuron or effector)
  • Nerve impulses travel along axons as action potentials.
  • At the axon terminal, action potentials trigger neurotransmitter release to transfer information
  • Synapses can be on dendrites, cell bodies, or axons
  • Neuroeffector junctions are synapses between neurons and other cell types
  • Neuro-muscular junctions are neuron-to-muscle cell synapses, while neuro-glandular junctions are neuron-to-secretory cell junctions.
  • Communication is unidirectional across a synapse.

Synapse Structure (Presynaptic and Postsynaptic Neuron)

  • A synaptic cleft, a narrow space, separates the plasma membranes of opposing neurons.
  • The presynaptic neuron releases neurotransmitters from its axon terminal
  • The postsynaptic neuron receives neurotransmitters at its membrane

Nerve Impulse Transmission at a Synapse

  • Arrival of an action potential depolarizes the axon terminal
  • Depolarization opens calcium channels, allowing calcium ions to enter.
  • This triggers synaptic vesicle exocytosis, releasing neurotransmitters into the synaptic cleft.
  • Neurotransmitters diffuse across the cleft and bind to receptors on the postsynaptic membrane.
  • Binding may cause depolarization (excitatory) or hyperpolarization (inhibitory) in the postsynaptic membrane.
  • Neurotransmitters are removed by enzymatic breakdown (e.g., AChE for acetylcholine) or reuptake.
  • Acetylcholine (ACh) is a common neurotransmitter at cholinergic synapses (widespread in & out of CNS).
  • Norepinephrine (NE), also called noradrenaline, functions at adrenergic synapses.
  • Neurotransmitter effects are temporary due to enzymatic breakdown or reuptake.

Cholinergic Synapse (Specific Example)

  • Action potential arrives and depolarizes presynaptic axon terminal
  • ACh is released, triggered by calcium influx
  • ACh binds to receptors on postsynaptic membrane, causing depolarization
  • AChE breaks down ACh into acetate and choline, ending its effect.

Neurotransmitter Effects and Drugs

  • Neurotransmitters can have excitatory or inhibitory effects.
  • Many drugs affect the nervous system by interacting with neurotransmitter receptors, altering perception, motor control, or emotional states.
  • The balance between excitatoryand inhibitory stimuli determines whether an action potential is generated in the postsynaptic neuron.

Neuronal Pools

  • Neuronal pools are groups of interconnected interneurons with specific functions.
  • Each pool has a limited number of inputs and outputs, and can have excitatory and inhibitory neurons.
  • Pool outputs may stimulate or inhibit other pools or motor neurons.

Divergence and Convergence (Neural Circuits)

  • Divergence: Information spreads from one neuron to many.
  • Convergence: Multiple neurons synapse on a single neuron, enabling both voluntary and involuntary control of body processes.

Meninges (Protection for CNS)

  • Meninges are 3 specialized membrane layers surrounding the brain and spinal cord.
  • Provide physical stability, shock absorption, and transport needed oxygen/nutrients.
  • Layers: dura mater, arachnoid, pia mater.

Dura Mater

  • Outermost layer; fused to the skull.
  • Two fibrous layers for the brain, separated by a gap.
  • Dural folds in brain help hold the brain in place.
  • Has epidural space in spinal cord (containing areolar tissue, blood vessels, and adipose tissue.)

Arachnoid

  • Separated from dura by the subdural space.
  • Contains lymphatic fluid for reducing friction.
  • Squamous epithelial cells form the layer.
  • Deep to arachnoid is the subarachnoid space (filled with CSF), providing shock absorption and transporting substances.

Pia Mater

  • Innermost layer; tightly bound to underlying neural tissue.
  • Blood vessels servicing the brain and spinal cord run along its surface within the subarachnoid space.
  • Highly vascular in the brain, supplying oxygen and nutrients.

Spinal Cord Structure

  • Approximately 45 cm long, with cervical and lumbar enlargements for limb control.

  • Tapered to a conus medullaris, where a fibrous filum terminale anchors it to coccyx.

  • A central canal filled with cerebrospinal fluid (CSF).

  • Posterior median sulcus and anterior median fissure are surface features.

  • 31 segments give rise to pairs of spinal nerves. (Cervical, thoracic, lumbar, sacral, coccygeal)

  • Spinal nerves are mixed nerves (sensory and motor fibers)

  • Cauda equina (horse’s tail) refers to the long ventral and dorsal roots of spinal nerves inferior to the spinal cord tip.

Spinal Cord Anatomy

  • Gray matter forms an "H" or butterfly shape around the central canal, with posterior and anterior horns.
  • White matter surrounds the gray matter—posterior, lateral, and anterior columns.
  • Contains ascending tracts (sensory information) and descending tracts (motor commands).

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Quiz Team

Description

Explore the intricate details of synapse structure and function in this quiz. Learn about how neurons communicate through synapses, including the mechanisms of neurotransmitter release and reception. Understand the differences between various types of synapses and their roles in nerve impulse transmission.

More Like This

Use Quizgecko on...
Browser
Open
Browser
Browser