Final Exam Quizlet

Components of CNS

Brain and spinal cord; responsible for memory, emotion, problem solving, reasoning, and movement.

Function of the spinal cord

Acts as a communication pathway between brain and body.

Components of PNS

All nerves outside CNS; includes somatic and visceral divisions.

Somatic Nervous System

Voluntary; controls skeletal muscles and receives sensory input from skin, muscles, and joints.

Visceral Nervous System

Involuntary; includes sympathetic and parasympathetic divisions and controls organ function.

Afferent division of PNS

Receives sensory information and carries it toward the CNS.

Efferent division of PNS

Sends motor commands away from the CNS to effectors.

Direction of afferent signals

Toward CNS.

Direction of efferent signals

Away from CNS.

Somatic targets

Skeletal muscles (voluntary).

Visceral targets

Organs, glands, smooth muscle (involuntary).

Direction of conduction in a neuron

From dendrites → soma → axon → axon terminals.

Oligodendrocytes

Form myelin sheaths in CNS.

Ependymal cells

Secrete and circulate cerebrospinal fluid (CSF).

Microglia

Immune macrophages in CNS.

Astrocytes

Most abundant CNS glial cells; support neurons, form blood-brain barrier.

Schwann cells

Form myelin sheaths around axons in PNS; assist regeneration.

Satellite cells

Support and protect neuron somas in PNS.

Myelin

Lipid-rich insulating sheath around axons that speeds nerve impulse conduction.

Myelin composition

Mostly lipids.

Function of myelin

Increases speed and efficiency of electrical conduction.

Saltatory conduction

Impulse jumps between nodes of Ranvier; occurs in myelinated axons; fast.

Continuous conduction

Impulse travels along entire axon; occurs in unmyelinated fibers; slow.

Tay-Sachs disease

Genetic disorder caused by lack of hexosaminidase; leads to neural degeneration.

Multiple sclerosis

Autoimmune destruction of CNS myelin causing muscle weakness and vision problems.

Local potentials

Graded changes in membrane potential on dendrites/soma; excitatory or inhibitory.

Action potentials

All-or-none electrical impulse occurring on the axon.

Ions in resting membrane potential

Na+, K+, leak channels (mostly K+ leaving cell).

Ions in EPSP

Na+ enters cell causing depolarization.

Ions in IPSP

Cl- enters or K+ exits causing hyperpolarization.

Requirements for nerve fiber regeneration

Intact soma and presence of Schwann cells/neurolemma.

Why CNS fibers do not regenerate

No Schwann cells; oligodendrocytes inhibit growth; scar tissue forms.

Average resting membrane potential

−70 mV.

Steps of an action potential

Stimulus → local potential → Na+ opens → depolarization → Na+ closes → repolarization via K+ → hyperpolarization → AP travels → Ca2+ enters terminal → neurotransmitter released.

Main inhibitory neurotransmitter

GABA.

Why GABA is inhibitory

Causes Cl- influx → hyperpolarizes membrane → prevents AP.

Synapse

Junction where a neuron communicates with another cell.

Presynaptic membrane

Axon terminal of sending neuron.

Postsynaptic membrane

Dendrite or soma of receiving cell (or muscle/gland).

Factors that increase conduction speed

Larger diameter and myelination.

Absolute refractory period

No AP can occur; Na+ channels are open or inactivated.

Relative refractory period

Stronger stimulus can produce AP; K+ channels still open.

How neural signals stop

Neurotransmitter removed by reuptake, enzymatic breakdown, or diffusion.

Diverging neural circuit

One neuron branches to many outputs.

Converging neural circuit

Many neurons input to one target neuron.

Ion involved in memory formation

Calcium (Ca2+).

Engram

Physical pathway of neurons that forms a memory.

Synaptic plasticity

Ability of synapses to change with learning or experience.

Group of neurons in CNS

Nucleus.

Group of neurons in PNS

Ganglion.

Temporal summation

Multiple signals from one presynaptic neuron arriving quickly.

Spatial summation

Multiple presynaptic neurons send simultaneous signals.

Functions of spinal cord

Conduction, neural integration, locomotion (central pattern generators), reflexes.

Epidural anesthesia location

Epidural space around spinal cord.

Anterior gray horn function

Motor neuron somas; axons exit as spinal nerves.

Posterior gray horn function

Receives sensory information.

Spinal cord area damaged in polio

Anterior gray horns (motor neurons).

Hydrocephaly

Abnormal buildup of CSF increasing pressure in ventricles.

Gray matter in brain

Neuron cell bodies, dendrites, synapses.

White matter in brain

Myelinated axons.

Midbrain

Controls motor function; processes vision and hearing.

Pons

Controls facial sensation, chewing, eye movement; balance and posture.

Cranial nerves from pons

CN V (trigeminal), CN VI (abducens), CN VII (facial), CN VIII (vestibulocochlear).

Substantia nigra location

Midbrain.

Parkinson's disease cause

Degeneration of dopamine-producing neurons → tremors.

Medulla oblongata function

Regulates breathing, heart rate, swallowing, digestion.

Blood-brain barrier function

Protects brain by regulating substances entering blood to brain.

Blood-brain barrier permeability

Most permeable to gases/alcohol; least permeable to large molecules/toxins.

CSF function

Cushions brain and spinal cord; circulates nutrients.

Cells that form CSF

Ependymal cells.

Main brain structures

Cerebrum, cerebellum, brainstem (midbrain, pons, medulla).

Gyri vs sulci

Gyri = ridges; sulci = grooves.

Corpus callosum

Broad band connecting right and left hemispheres.

Pineal gland

Produces melatonin and regulates circadian rhythms.

Frontal lobe functions

Decision-making, planning, mood, voluntary movement, speech production.

Parietal lobe functions

Somatic sensation, taste, sensory integration, spatial awareness.

Temporal lobe functions

Hearing, smell, emotion, language comprehension, memory.

Occipital lobe functions

Visual processing and awareness.

Insula functions

Pain, visceral sensation, emotion, empathy, homeostasis.

Projection tracts

Connect cortex with lower brain and spinal cord.

Association tracts

Connect regions within the same hemisphere.

Commissural tracts

Connect left and right hemispheres via corpus callosum.

Three parts of diencephalon

Thalamus, hypothalamus, epithalamus.

Hypothalamus

functions Regulates homeostasis (temperature, hunger, thirst).

Medulla oblongata

functions Controls vital autonomic functions (respiration, heart rate).

Limbic system

functions Emotion and memory.

Cerebellum

functions Coordinates movement, balance, motor learning.

Primary visual cortex

Occipital lobe.

Primary auditory cortex

Temporal lobe.

Precentral gyrus function

Primary motor cortex.

Postcentral gyrus function

Primary somatosensory cortex.

Aphasia

Language impairment.

Agnosia

Inability to recognize objects despite intact senses.

Autonomic meaning

Involuntary control of body functions.

Divisions of ANS

Sympathetic (fight-or-flight) and parasympathetic (rest-and-digest).

Somatic vs autonomic targets

Somatic → skeletal muscle; Autonomic → organs/glands/smooth muscle.

Somatic vs autonomic speed

Somatic = faster (myelinated); Autonomic = slower.

Motor neurons in somatic vs autonomic

Somatic = 1 motor neuron; Autonomic = 2-neuron chain.

Sympathetic origin

Thoracolumbar (T1-L2).

Parasympathetic origin

Craniosacral (CN III, VII, IX, X and S2-S4).