A&P Test 3

Classify the organs of the nervous system into central and peripheral divisions and their subdivisions, and indicate the paths of afferent and efferent information.

CNS includes brain and spinal cord; PNS includes cranial and spinal nerves. Afferent pathways carry sensory info to CNS; efferent pathways carry motor commands from CNS.

Describe the internal and external structures of the neuron and their functions.

Internal: nucleus, mitochondria, ER. External: dendrites (receive signals), axon (sends signals), axon terminals, myelin sheath.

Identify neurons on the basis of their structural and functional classifications.

Structural: multipolar, bipolar, unipolar. Functional: sensory, motor, interneurons.

Describe the different forms, locations, and purposes of different types of neuroglia.

Astrocytes (support/Blood-Brain Barrier), Microglia (immune), Oligodendrocytes (CNS myelin), Schwann cells (PNS myelin), Ependymal cells (CSF).

Describe the purpose of the myelin sheath.

Insulates axons, increases conduction speed, aids in axonal regeneration (PNS).

Describe the difference between gray and white matter.

Gray matter = neuron cell bodies; White matter = myelinated axons.

Describe how the resting membrane potential is generated, including the role of leak channels, organic anions, and the sodium/potassium pump.

Na⁺/K⁺ pump, leak channels, and negative proteins create a resting potential around -70mV.

Distinguish between action potential and graded potentials, describe the basic characteristics of action and graded potentials.

Graded: localized, variable strength. Action: all-or-none, travels along axon.

Identify the basic types of ion channels and the stimuli that operate gated ion channels.

Leak (always open), voltage-gated (electric), ligand-gated (chemical), mechanically gated (physical).

Describe the sequence of events involved in generation of an action potential.

1) Depolarization (Na⁺ in), 2) Repolarization (K⁺ out), 3) Hyperpolarization, 4) Resting state.

Explain absolute and relative refractory periods.

Absolute: no new AP possible. Relative: new AP requires stronger stimulus.

Compare structure and functional differences of different fiber types.

A fibers: large, myelinated, fast. B fibers: small, myelinated. C fibers: small, unmyelinated, slow.

Compare and contrast continuous and saltatory conduction.

Continuous: unmyelinated, slower. Saltatory: myelinated, faster, jumps at nodes.

Explain the events that occur at a chemical synapse.

AP arrives → Ca²⁺ enters → neurotransmitter released → binds to receptor → opens ion channel.

Explain how graded potentials influence the formation of an action potential.

If threshold is reached at axon hillock, an AP is generated.

Describe EPSPs and IPSPs, and how these potentials are related to various ion channels.

EPSPs: Na⁺ or Ca²⁺ influx → depolarize. IPSPs: K⁺ efflux or Cl⁻ influx → hyperpolarize.

Distinguish between spatial and temporal summation.

Spatial: multiple synapses at once. Temporal: one synapse repeatedly.

Describe and give examples and functions of the various neurotransmitter classes.

ACh (muscle), Dopamine (reward), Serotonin (mood), GABA (inhibition), Glutamate (excitation).

Distinguish between ionotropic and metabotropic receptor mechanisms.

Ionotropic: direct channel opening. Metabotropic: G-protein/2nd messenger systems.

Describe the various types of neuronal circuits in the nervous system.

Diverging, converging, reverberating, parallel after-discharge—each for different processing needs.

Discuss the effects of damage on the peripheral nervous system and the steps required for repair.

Axons may regenerate if Schwann cells remain; steps: degeneration, sprouting, reconnection.

Define a reflex, and describe the components of a reflex arc.

Reflex: involuntary response. Components: receptor, sensory neuron, integration center, motor neuron, effector.

Explain the stretch reflex, withdrawal reflex, and crossed-extensor reflex.

Stretch: contracts muscle. Withdrawal: pulls away from pain. Crossed-extensor: supports opposite limb.

Identify the principle parts of the brain.

Cerebrum, diencephalon, brainstem, cerebellum.

Discuss the locations of the cerebral lobes with respect to the topical landmarks, and describe their BASIC functions.

Frontal (motor, thinking), Parietal (sensory), Temporal (hearing), Occipital (vision), Insula (taste).

Note that specific areas of the brain have identifiable functions that correspond to sensory, motor, and associative capacities.

Sensory = postcentral gyrus, Motor = precentral gyrus, Association = integration across cortex.

Define the location and purpose of the primary somatosensory cortex.

Located in postcentral gyrus; processes touch, pain, pressure, temperature.

Locate the primary motor area on the cortex and indicate the types of movements it controls.

Located in precentral gyrus; controls voluntary skeletal muscle movement.

Understand the concept of somatic sensory and somatic motor maps in the cerebral cortex.

Sensory/motor homunculi show body region distribution in respective cortical areas.

Discuss the components of specific somatosensory pathways and the functions of these pathways (dorsal-column pathway, spinothalamic tract, spinocerebellar tract).

Dorsal column: fine touch. Spinothalamic: pain/temp. Spinocerebellar: proprioception.

Discuss the components of the corticospinal tracts and know the function of this tract.

Origin: motor cortex. Function: voluntary motor control.

List the necessary requirements for the perception of a sensory event.

Stimulus, receptor, conduction pathway, CNS interpretation.

Describe the structure of the olfactory epithelium, olfactory receptor, taste bud and gustatory receptors. How are the receptor mechanisms for olfaction and gustation similar and how are they different?

Both use chemoreceptors; olfaction = airborne, taste = dissolved; different transduction methods.

Describe the basic mechanisms which allow us the distinguish tastes and smells.

Taste = receptor-specific depolarization; smell = pattern recognition of odorant combinations.

Describe the path of olfactory and gustatory information from the receptor to the cerebral cortex.

Olfaction: nose → bulb → cortex. Gustation: tongue → cranial nerves → thalamus → cortex.

List and describe the accessory structures of the eye and the structural component of the eyeball.

Accessory: lids, lashes, lacrimal glands. Eyeball: cornea, lens, retina, iris, etc.

Discuss the role of the cornea, pupil, iris, and lens in image formation on the retina.

Cornea/lens focus light. Pupil/iris regulate light entry.

Describe how the size of the pupil and shape of the lens are controlled.

Pupil = iris muscles. Lens = ciliary muscles adjusting tension on suspensory ligaments.

Describe the following eye abnormalities: myopia, hypermetropia, astigmatism, presbyopia, and glaucoma.

Myopia = nearsight. Hypermetropia = farsight. Astigmatism = uneven lens. Presbyopia = aging. Glaucoma = pressure/nerve damage.

Describe the structure of the retina.

Layers: rods/cones → bipolar cells → ganglion cells → optic nerve.

Describe the processing of visual signals in the retina and the pathway visual information takes from the retina to the visual cortex.

Retina → optic nerve → chiasm → thalamus → visual cortex.

Describe the anatomy and the major structures of the three main regions of the ear.

Outer (pinna), middle (ossicles), inner (cochlea, vestibule, canals).

Describe the path of sound energy from the outside air to the inner ear.

Sound → tympanic membrane → ossicles → oval window → cochlear fluid.

Describe the structure of the spiral organ.

Located in cochlea; contains hair cells on basilar membrane.

Describe the structure of the auditory hair cell and distinguish between the functions of the outer and inner hair cells.

Inner: detect sound. Outer: amplify. Both have stereocilia that respond to fluid movement.

Explain how sound energy is transduced into chemical and electrical signals, and the pathway of sound information from the spiral organ to the auditory cortex.

Stereocilia bend → depolarize → neurotransmitter release → cochlear nerve → brainstem → cortex.

Explain how the structure of the basilar membrane allows for separation of sound frequencies.

Base = stiff/high freq. Apex = flexible/low freq.

Identify the receptor organs for static and dynamic equilibrium and describe how they function.

Static = maculae (utricle/saccule). Dynamic = cristae (semicircular canals).

Describe the locations and functions of the various general sensory receptors for tactile, thermal, pain, and proprioceptive stimuli.

Tactile = Meissner/Merkel. Thermal = thermoreceptors. Pain = nociceptors. Proprioception = muscle/joint receptors.