Overview of Nervous System Function and Anatomy

Flashcards covering the functional overview of the nervous system, types of neurons and neuroglia, action potential mechanics, brain structure, meninges, and the autonomic nervous system based on the provided lecture transcript.

Sensory input

A general function of the nervous system that detects changes in and outside of the body.

Integration and processing

A general function of the nervous system involved in making decisions.

Motor output

A general function of the nervous system that stimulates muscles and glands to respond.

Central Nervous System (CNS)

The division of the nervous system consisting of the brain and spinal cord.

Peripheral Nervous System (PNS)

Connects the CNS to other body parts and consists of cranial nerves and spinal nerves.

Afferent (sensory) subdivision

Subdivision of the PNS where impulses are conducted along peripheral nerves to the CNS for integration.

Efferent (motor) subdivision

Subdivision of the PNS consisting of neurons that transmit impulses from the CNS to effectors.

Effectors

Muscles or glands outside the nervous system that perform motor functions.

Somatic Nervous System (SNS)

A subdivision of the efferent system that transmits voluntary commands to skeletal muscles.

Autonomic Nervous System (ANS)

A subdivision of the efferent system that transmits involuntary commands to viscera (organs).

Neurons

Specialized cells that react to environmental changes and can carry an electric impulse.

Neuroglia

Cells that support, protect, and nourish neurons but do not carry electric impulses.

Cell body (Soma)

The part of the neuron that runs the activity of the cell.

Dendrites

Cytoplasmic extensions of the cell body that work as increased surface for reception of cell signals.

Axon

A neuronal extension that carries the action potential (nerve impulse).

Synaptic knobs

Structures at the ends of axons that contain vesicles of neurotransmitters.

Interneurons

Types of neurons categorized by function that connect different parts of the CNS.

Myelinated axons

Axons coated by a lipid-rich myelin sheath which increases conduction speed for electrical impulses.

Schwann cells

Cells that produce the myelin sheath along axons in the PNS.

Oligodendrocytes

Neuroglia in the CNS that myelinate CNS axons and provide structural support.

Nodes of Ranvier

Spaces between the myelin on the axon.

White Matter

Groups of myelinated axons in the CNS.

Saltatory conduction

A signal transmission method that allows the signal to skip down the nodes of Ranvier, making it faster than unmyelinated axons.

Ganglia

Clusters of cell bodies in the PNS.

Nuclei

Clusters of cell bodies in the CNS.

Multipolar neurons

Neurons with many processes extending from the cell body (many dendrites, 1 axon), constituting $99\%$ of neurons.

Astrocytes

Neuroglia of the CNS that connect neurons to blood vessels and form part of the Blood Brain Barrier.

Microglia

Phagocytic cells in the CNS that also provide structural support.

Ependyma (ependymal cells)

Cells that line the central canal of the spinal cord and ventricles of the brain, helping regulate cerebrospinal fluid composition.

Satellite Cells

Neuroglia of the PNS that support clusters of neuron cell bodies (ganglia) and are vital for nerve regeneration.

Resting membrane potential

The electrical potential of a neuron at rest, appearing as $-70\,mV$.

Threshold stimulus

The level of stimulation ($-55\,mV$) required to stimulate an action potential at the trigger zone.

Depolarization

The process where $Na^+$ enters the cell, making the inside of the cell more positive.

Repolarization

The process where $K^+$ channels open and $K^+$ diffuses out of the cell, returning the membrane to a negative charge.

Absolute Refractory Period

Time when threshold stimulus cannot generate another action potential because voltage-gated $Na^+$ channels are briefly unresponsive.

Relative Refractory Period

Time when only a high-intensity stimulus can generate another action potential because repolarization is not complete.

Reuptake

A method of removing neurotransmitters where they are pulled back into the presynaptic neuron for re-use.

Enzymatic degradation

A method where certain enzymes break down neurotransmitters in the synaptic cleft or presynaptic terminal.

Convergence

A neuronal pool configuration where one neuron receives input from the axons of several neurons.

Divergence

A neuronal pool configuration where one neuron sends impulses to several neurons, amplifying the impulse.

Dura mater

The tough, dense connective tissue outer layer of the meninges.

Arachnoid mater

The middle, web-like layer of the meninges; the subarachnoid space contains cerebrospinal fluid.

Pia mater

The inner layer of the meninges attached to the surface of the brain and spinal cord, containing blood vessels.

Cerebrospinal Fluid (CSF)

A clear watery secretion ($\approx 140\,mL$ volume) that is nutritive and protective for CNS neurons.

Choroid plexuses

Special capillaries of the pia mater covered by ependymal cells that secrete CSF.

Arachnoid granulations

Structures that absorb CSF after it has exchanged substances.

Frontal lobe

The cerebral lobe responsible for higher intellectual processes and personality.

Parietal lobe

The cerebral lobe responsible for sensory processing and integration.

Temporal lobe

The cerebral lobe responsible for language and auditory processing.

Occipital lobe

The cerebral lobe responsible for visual processing.

Insula

The cerebral lobe responsible for internal body status.

Corpus callosum

Connects the two cerebral hemispheres.

Gyri

Ridges or convolutions on the surface of the brain.

Sulci

Shallow grooves in the brain surface, such as the Central sulcus.

Wernicke’s area

Sensory speech area located in the temporal/parietal lobe responsible for understanding language.

Broca’s area

Anterior to the primary motor cortex, this area controls muscles needed for speech.

Thalamus

The gateway for sensory impulses (except smell) ascending to the cerebral cortex.

Hypothalamus

Maintains homeostasis by regulating visceral activities like heart rate, body temperature, and the pituitary gland.

Limbic System

Controls emotional responses, feelings, and behavior oriented toward survival.

Reticular formation

A network of nerve pathways in the brainstem that determines alertness and sleep/wake cycles.

Arbor vitae

The white matter found within the cerebellum.

Conus medullaris

The tapering region below the lumbar enlargement forming the tip or end of the spinal cord.

Filum terminale

A cord of connective tissue that anchors the spinal cord to the coccyx.

Cauda equina

A bundle of nervous tissue (lumbar and sacral nerves) extending downward from the conus medullaris.

Dermatome

A region of the skin innervated by a single spinal nerve.

Endoneurium

Loose connective tissue that surrounds individual axons.

Perineurium

Loose connective tissue that surrounds fascicles.

Epineurium

Dense connective tissue that surrounds a group of fascicles.

Sympathetic division

The division of the ANS that prepares the body for 'fight or flight' situations and has short pre-ganglionic fibers.

Parasympathetic division

The division of the ANS that prepares the body for 'rest and digest' activities and has long pre-ganglionic fibers.

Sympathetic tone

Constant low-level activity that keeps the body in homeostasis, such as maintaining blood pressure via smooth muscle stimulation.