Neuroscience Quiz: Nervous System Functions

Corticospinal Tract

• Major neural pathway in the central nervous system (CNS)
• Carries motor commands from the brain's motor cortex to the spinal cord
• Located in white matter of brain and spinal cord
• Controls voluntary movements, especially fine motor movements of limbs and hands

Triceps Reflex Movements

• Monosynaptic reflex
• Triggered by tapping the triceps tendon
• Causes the triceps brachii muscle to contract, extending the forearm

Synaptic Knobs

• Terminal ends of axons
• Contain synaptic vesicles filled with neurotransmitters
• Release neurotransmitters into the synaptic cleft to transmit signals

Sensory Nerve Fiber Crossover

• Results in contralateral (opposite side) sensation
• Sensory information from one side of the body is processed in the opposite side of the brain

EPSPs and IPSPs

• EPSPs (excitatory postsynaptic potentials) depolarize the postsynaptic membrane, increasing the likelihood of an action potential
• IPSPs (inhibitory postsynaptic potentials) hyperpolarize the membrane, making an action potential less likely

Cerebrospinal Fluid (CSF)

• Clear fluid produced by choroid plexus in brain ventricles
• Cushions the brain and spinal cord
• Removes waste
• Maintains chemical stability of the CNS

Adrenergic Fibers

• Release norepinephrine (noradrenaline) as a neurotransmitter
• Found in the sympathetic nervous system
• Regulate functions like heart rate and blood pressure

Transmission of Impulses Between Neurons

• Neurotransmitters released from presynaptic neuron into synaptic cleft
• Neurotransmitters bind to receptors on postsynaptic neuron, triggering an excitatory or inhibitory signal

Functional Unit of Muscle Contraction

• Sarcomere, segment between two Z-lines in a myofibril
• Contains actin and myosin filaments
• Interaction of these filaments is responsible for muscle contraction

Rigor Mortis

• Muscle stiffening after death
• Occurs because ATP is unavailable to detach myosin from actin, keeping muscles contracted

Threshold Stimulus

• Minimal stimulus required
• Causes a neuron to reach its threshold potential, generating an action potential

Muscle Characteristics

• Skeletal Muscle: Striated, voluntary, multinucleated, attached to bones
• Smooth Muscle: Non-striated, involuntary, single-nucleated, in organs like intestines and blood vessels
• Cardiac Muscle: Striated, involuntary, single or binucleated, found in the heart

Action Potential Steps

• Depolarization: Na+ channels open, Na+ rushes into the cell
• Repolarization: K+ channels open, K+ exits the cell
• Saltatory Conduction: Action potentials "jump" along myelinated axons

Synapse

• Junction between two neurons or neuron and another cell type
• Neurotransmitters are released to transmit signals

Somatic and Autonomic Nervous Systems

• Somatic Nervous System (SNS): Controls voluntary muscle movements
• Autonomic Nervous System (ANS): Controls involuntary functions like heart rate and digestion

Striated Skeletal Muscles

• Appear striated due to actin and myosin filaments arrangement in sarcomeres

Events of Muscle Contraction

• Excitation (nerve impulse triggers acetylcholine release)
• Action Potential Propagation (impulse travels along muscle fiber and into T-tubules)
• Calcium Release (calcium ions released from sarcoplasmic reticulum)
• Cross-Bridge Formation (myosin heads attach to actin)
• Relaxation (calcium reabsorbed, muscle relaxes)

Reticular Formation

• Involved in regulating wakefulness, sleep cycles, and attention
• Controls some reflexes

ATP and Creatine Phosphate

• Creatine phosphate acts as a quick energy source converting ADP back to ATP during intense muscular activity

Forebrain Development

• Develops into structures involved in higher brain functions (cerebrum, thalamus, hypothalamus) such as cognition, emotion, and sensory processing

Broca's Area

• Involved in speech production
• Located in the left frontal lobe

Brain Waves

• Record electrical activity in the brain
• Classified as delta, theta, alpha, and beta waves

Axon Regeneration Differences

• Axons in the peripheral nervous system (PNS) regenerate better than those in the CNS

Drug Tolerance

• Brain adjusts to neurotransmitter alterations caused by drugs
• Reduced drug efficacy due to receptor desensitization or downregulation

Muscle Fiber Composition

• Myofibrils are made of repeating units called sarcomeres, composed of actin (thin) and myosin (thick) filaments

Bones and Muscles as Mechanical Devices

• Bones act as levers, joints are pivot points, muscles provide force for movement

Major Parts of the Diencephalon

• Includes thalamus, hypothalamus, epithalamus, and subthalamus
• Regulate sensory processing, autonomic functions, and emotional responses

Rapid Conduction in Axons

• Most rapid conduction in myelinated axons where action potential "jumps" between nodes of Ranvier.

Meningitis Effects

• Inflammation of the meninges (protective layers surrounding brain and spinal cord), potentially damaging the CNS

Neuronal Pools

• Interneurons organize into neuronal pools to integrate and process signals

Meningeal Layers

• Dura Mater (outermost layer), tough and protective, containing cerebrospinal fluid
• Arachnoid Mater (middle layer)
• Pia Mater (innermost layer) closely adhered to brain and spinal cord

Partial Sustained Contraction

• Tonic contraction where muscles maintain a steady level of tension (e.g. postural muscles)

Brain Area for Voluntary Movements

• Cerebellum coordinates voluntary movements, balance, and fine motor skills

Gray and White Matter

• Gray matter: neuron cell bodies, dendrites, unmyelinated axons (processing and integration)
• White matter: myelinated axons(transmit signals over long distances)

Dermatome

• Area of skin innervated by sensory fibers from a single spinal nerve (helps to localize nerve damage)

Neurotransmitter Release

• Neurotransmitters released from synaptic vesicles via exocytosis when an action potential reaches the synaptic terminal

Agonists, Antagonists, and Prime Movers

• Agonists: Chemicals activating receptors
• Antagonists: Chemicals blocking receptor activity
• Prime movers: Muscles responsible for the primary action in a movement

Muscle Contraction (Rapid Stimuli)

• Individual twitches combine through summation
• Strong, smooth contraction without relaxation if stimuli are frequent

Reflex Arc Components

• Receptor: detects a stimulus
• Sensory Neuron: sends signal to CNS
• Integration Center: CNS processes information
• Motor Neuron: sends response from CNS to effector
• Effector: executes response, such as a muscle or gland

Brain Fissures

• Longitudinal Fissure: divides left and right hemispheres
• Central Sulcus: Divides frontal and parietal lobes
• Lateral/Sylvian Fissure: Separates temporal from frontal and parietal lobes
• Transverse Fissure: Separates cerebrum from cerebellum

Phrenic Nerve Plexus

• Innervates the diaphragm for breathing
• Arises from cervical plexus (C3-C5)

CNS vs. PNS

• CNS: Brain and spinal cord
• PNS: Cranial nerves, spinal nerves, and peripheral nerves

Crossed Extensor Reflex

• Complements the withdrawal reflex for maintaining balance

Neuron Structure and Function

• Dendrites: receive signals
• Cell body/soma: contains nucleus and processes info
• Axon: conducts impulses
• Axon terminals: release neurotransmitters

Muscle Cell Structure and Function

• Sarcolemma: muscle cell membrane
• Myofibrils: contain actin and myosin for contraction
• Sarcoplasmic reticulum: stores and releases calcium for contraction

Motor Unit Recruitment

• Increasing the number of motor units activated in response to intense stimulation

Drugs Inhibiting Monoamine Oxidase

• Increase availability of neurotransmitters, such as serotonin, norepinephrine, and dopamine

Myelin

• Lipid rich sheath surrounding axons
• Increases nerve impulse conduction speed

How Myelin is Produced

• Schwann cells (PNS) and Oligodendrocytes (CNS)

Gray and White Matter in Spinal Cord

• Anterior Horn: Motor neurons
• Posterior Horn: Sensory neurons
• Lateral Horn: Autonomic neurons

Types of Neurons

• Bipolar: single axon and dendrite
• Unipolar: single process splitting into two
• Multipolar: many dendrites, one axon

Acetylcholine Degradation

• Acetylcholinesterase breaks down acetylcholine in the synaptic cleft

Skeletal Muscle and Body Temperature

• Skeletal muscle contractions generate heat to maintain body temperature

Neuron Characteristics

• Excitability: Responds to stimuli
• Conductivity: Transmit electrical impulses
• Secretion: Release neurotransmitters

Aphasia

• Language disorder caused by brain damage (e.g., affecting speech, comprehension)

Cerebral Association Areas

• Integrate sensory input, memory, reasoning, and emotions to enable complex tasks

Functional Connection Between Neurons

• Synapse serves as connections between neurons allowing signal transmission via neurotransmitters

Functions of Neurons

• Sensory Neurons: Carry signals to CNS
• Motor Neurons: Carry signals from CNS to effectors
• Interneurons: Integrate information within CNS

Muscle Origin and Insertion

• Origin: fixed attachment point
• Insertion: movable attachment point

CNS and PNS Cells

• CNS: astrocytes, oligodendrocytes, microglia, ependymal cells
• PNS: Schwann cells, satellite cells

Spinal Nerve Injuries

• Result from trauma, compression (e.g., herniated disc, inflammation)
• Can cause motor or sensory deficits

Neuromuscular Junction (NMJ)

• Where motor neuron meets muscle fiber
• Acetylcholine released to trigger muscle contraction

Motor Unit

• Motor neuron and all muscle fibers it innervates
• Consists of a motor neuron and all the muscle fibers it innervates

Threshold Stimulus

• Minimum stimulus needed to depolarize the membrane and generate an action potential (causes an action potential)

Convergence and Divergence

• Convergence: Multiple neurons signal to one neuron
• Divergence: One neuron signals to multiple neurons

Connective Tissue Layers

• Muscle cells: Epimysium (entire muscle), perimysium (fascicles), endomysium (individual fibers)
• Nerve cells: Epineurium (entire nerve), perineurium (fascicles), endoneurium (individual fibers)

Steps After Threshold Potential

• Sodium channels open (depolarization)

Potassium Channels and Sodium Potassium Pumps

• Potassium channels open for repolarization
• Sodium-potassium pump restores resting potential
• Neuron Cell Bodies in PNS: Clusters called ganglia

Basal Ganglia Location and Function

• Located in cerebrum
• Control voluntary motor movements, procedural learning, and habits

Cerebral Cortex

• Outer layer of gray matter
• Involved in higher brain functions

Hemispheric Dominance

• One hemisphere (usually left) controlling language and analytical tasks

Limbic System

• Regulates emotions and memory

Na+ and K+ in Neurons

• Na+ enters the neuron during depolarization
• K+ exits the neuron during repolarization
• Sodium-potassium pump restores ionic balance