Nervous System Quiz

Nervous System Divisions

• Central Nervous System (CNS): Brain and spinal cord
• Peripheral Nervous System (PNS): Nerves that connect the CNS to the rest of the body

Definitions

• Ganglion: a cluster of neuron cell bodies located outside the CNS
• Nerve: a bundle of axons that transmit signals between the CNS and other parts of the body
• Nucleus: a cluster of neuron cell bodies located within the CNS
• Receptor: a specialized cell or structure that detects a specific stimulus
• Effector: a muscle or gland that carries out a response to a stimulus

Neuron Types

• Sensory neurons: transmit signals from receptors to the CNS
• Interneurons: connect neurons within the CNS, responsible for processing and integrating information
• Motor neurons: transmit signals from the CNS to effectors

Neuron Anatomy

• Cell body (soma): contains the nucleus and other organelles
• Axon: a long, slender extension that transmits signals away from the cell body
• Dendrites: branched extensions that receive signals from other neurons

Glial Cells

• Astrocytes: support and nourish neurons, regulate the blood-brain barrier
• Oligodendrocytes (CNS) and Schwann cells (PNS): produce myelin, insulating the axons and speeding up signal transmission
• Microglia: phagocytic cells that remove cellular debris and pathogens

Myelination

• Myelin: a fatty substance that insulates axons, increasing the speed of signal conduction
• Nodes of Ranvier: gaps in the myelin sheath, allowing for saltatory conduction, where the signal jumps from node to node

Nerve Regeneration

• PNS: limited regeneration possible due to Schwann cells guiding axonal growth
• CNS: regeneration is very limited due to the lack of Schwann cells and the presence of inhibitory factors

Synapse Anatomy

• Synapse: the junction between two neurons where communication occurs
• Presynaptic neuron: releases neurotransmitters into the synaptic cleft
• Postsynaptic neuron: receives neurotransmitters
• Synaptic cleft: the space between the presynaptic and postsynaptic neurons

Neuronal Circuits

• Converging circuits: multiple neurons converge onto a single neuron, allowing integration of information
• Diverging circuits: a single neuron branches to multiple neurons, allowing for amplification of a signal
• Reverberating circuits: neurons are organized in a loop, creating repetitive patterns to amplify the signal or create a rhythmic pattern.

Spinal Cord Gross Anatomy

• Cervical, Thoracic, Lumbar, Sacral, Coccygeal regions
• Central canal: filled with cerebrospinal fluid (CSF)
• Gray matter: contains neuron cell bodies, dendrites, and unmyelinated axons
• White matter: contains myelinated axons

Gray vs. White Matter

• Gray matter: involved in processing information and forming connections between neurons
• White matter: responsible for communicating information between different parts of the CNS

Nerve Anatomy

• Endoneurium: surrounds individual axons
• Perineurium: surrounds bundles of axons (fascicles)
• Epineurium: surrounds the entire nerve

Rootlets to Rami

• Rootlets: small bundles of axons that emerge from the spinal cord
• Dorsal roots: contain sensory axons
• Ventral roots: contain motor axons
• Spinal nerve: formed by the fusion of dorsal and ventral roots
• Rami: branches of spinal nerves that innervate specific regions of the body
• Dorsal rami: innervate the back
• Ventral rami: innervate the front and limbs

Nerve Plexuses

• Cervical plexus: innervates the neck, shoulders, and diaphragm
• Brachial plexus: innervates the upper limbs
• Lumbar plexus: innervates the lower limbs
• Sacral plexus: innervates the lower limbs and pelvic region

Meninges

• Dura mater: outer, tough layer
• Arachnoid mater: middle, web-like layer
• Pia mater: inner, delicate layer that adheres to the surface of the brain and spinal cord
• Subarachnoid space: space between the arachnoid mater and pia mater, filled with CSF

Spinal Tracts

• Ascending tracts: carry sensory information from the body to the brain
• Descending tracts: carry motor commands from the brain to the body

Neuron Types

• First-order neuron: receives sensory input from receptors
• Second-order neuron: receives information from the first-order neuron and transmits it to the thalamus
• Third-order neuron: receives information from the thalamus and transmits it to the cerebral cortex

Upper vs. Lower Motor Neurons

• Upper motor neurons (UMN): located in the cerebral cortex, control voluntary movement
• Lower motor neurons (LMN): located in the brainstem or spinal cord, directly innervate muscle fibers

Reflex Arcs

• Reflex: an involuntary, rapid response to a stimulus
• Reflex arc: the neural pathway involved in a reflex
• Components of a reflex arc: receptor, sensory neuron, interneuron, motor neuron, effector

Nerve Innervation and Spinal Cord Injuries

• Spinal nerves: can be damaged by injury, causing loss of sensation or motor function
• Complete spinal cord injury: all function below the level of the injury is lost
• Incomplete spinal cord injury: some function below the level of the injury is preserved

Major Brain Landmarks

• Cerebrum: the largest part of the brain, responsible for higher cognitive functions
• Cerebellum: located at the back of the brain, responsible for coordination and balance
• Brainstem: connects the cerebrum and cerebellum to the spinal cord, responsible for vital functions like breathing and heart rate

Dural Venous Sinuses

• Dural venous sinuses: spaces between the layers of dura mater that collect venous blood from the brain
• Superior sagittal sinus: a large sinus that runs along the top of the brain
• Transverse sinus: connects the superior sagittal sinus to the sigmoid sinus
• Sigmoid sinus: drains into the jugular vein

Cerebrospinal Fluid (CSF) Production & Flow

• CSF: a clear, colorless fluid that circulates through the CNS, providing cushioning, nutrient supply, and waste removal
• Produced by: choroid plexuses, vascular structures located in the ventricles of the brain
• Flow: ventricles (lateral, third, fourth) – subarachnoid space – absorbed into venous blood

Brainstem Functions

• Midbrain: controls eye movements, auditory reflexes, and motor control
• Pons: relays signals between the cerebrum and cerebellum, controls breathing, and sleep
• Medulla oblongata: controls heart rate, blood pressure, and breathing

Cerebellar Anatomy

• Two cerebellar hemispheres
• Vermis: the narrow strip of tissue that connects the hemispheres
• Folia: folds on the surface of the cerebellum
• Arbor vitae: the tree-like pattern of white matter

Cerebellum Function

• Coordination and balance: receives information from the cerebrum, inner ear, and muscles, and adjusts motor output to ensure smooth, coordinated movements
• Motor learning and memory: plays a role in learning and refining motor skills
• Cognitive functions: may also be involved in higher cognitive functions such as language and attention

Diencephalon

• Thalamus: relays sensory information to the cerebral cortex
• Hypothalamus: controls body temperature, hunger, thirst, and other homeostatic functions
• Epithalamus: includes the pineal gland, which secretes melatonin

Cerebral Lobes and Major Functions

• Frontal lobe: responsible for planning, decision-making, language, and voluntary movement
• Parietal lobe: responsible for sensory perception, spatial awareness, and motor control
• Temporal lobe: responsible for hearing, memory, and language comprehension
• Occipital lobe: responsible for visual processing

Limbic System

• Hippocampus: involved in memory formation and consolidation
• Amygdala: involved in emotional responses, especially fear and aggression
• Hypothalamus: controls basic drives and emotions
• Cingulate gyrus: involved in emotional processing and behavior regulation

Primary Sensory Cortices

• Somatosensory cortex: receives sensory input from the body
• Visual cortex: receives visual input
• Auditory cortex: receives auditory input
• Gustatory cortex: receives taste input
• Olfactory cortex: receives smell input

White Matter Tract Types

• Association fibers: connect areas within the same hemisphere
• Commissural fibers: connect areas between hemispheres
• Projection fibers: connect the cerebrum to lower brain structures and the spinal cord

Motor Function, Basal Nuclei, and Substantia Nigra

• Basal nuclei: a group of nuclei deep within the cerebrum that help control voluntary movements, posture, and muscle tone
• Substantia nigra: a brain structure that produces dopamine, a neurotransmitter involved in movement control

Cranial Nerve Number & Function

• 12 pairs of cranial nerves: numbered I-XII
• Functions: sensory (vision, hearing, taste, smell), motor (eye, jaw, facial, tongue movements), and mixed (sensory and motor)

Hemispheric Lateralization and Language

• Cerebral hemispheres: specialized for different functions
• Left hemisphere: typically dominant for language, speech, and logic
• Right hemisphere: typically dominant for spatial processing, music, and artistic ability

Autonomic vs. Somatic NS

• Somatic nervous system: controls voluntary movements of skeletal muscles
• Autonomic nervous system (ANS): regulates involuntary functions such as heart rate, breathing, digestion, and blood pressure

Sympathetic vs. Parasympathetic Structure and Function

• Sympathetic nervous system (fight-or-flight): prepares the body for stressful situations
• Parasympathetic nervous system (rest-and-digest): promotes relaxation and conserves energy

ANS Pathways

• Sympathetic: preganglionic neurons are short, postganglionic neurons are long
• Parasympathetic: preganglionic neurons are long, postganglionic neurons are short

ANS Neurotransmitters

• Sympathetic: norepinephrine and epinephrine
• Parasympathetic: acetylcholine

ANS Antagonism, Coopertivity, and Autonomic Tone

• Antagonism: sympathetic and parasympathetic systems often have opposing effects
• Cooperativity: systems can work together to achieve a common goal
• Autonomic tone: the balance between sympathetic and parasympathetic activity always has a slight activation of both systems, but one is usually dominant

Sensory Receptor Classification

• Mechanoreceptors: respond to mechanical stimuli (pressure, touch, sound, vibration)
• Chemoreceptors: respond to chemical stimuli (taste, smell, pH)
• Photoreceptors: respond to light stimuli (vision)
• Thermoreceptors: respond to temperature stimuli
• Nociceptors: respond to painful stimuli

Receptive Field

• Receptive field: the area of the body or environment that, when stimulated, will activate a particular sensory receptor