Nervous System, Senses, and Reflexes Lecture Notes

Comprehensive vocabulary flashcards covering the somatic and autonomic nervous systems, cranial nerves, motor/sensory pathways, receptors, and special senses including vision, hearing, taste, and smell.

Somatic Nervous System

Voluntary system controlling skeletal muscle via $1$ LMN utilizing ACh; always excitatory.

Autonomic Nervous System

Involuntary system controlling cardiac/smooth muscle and glands via $2$ LMNs utilizing ACh/NE; can be excitatory or inhibitory.

Sensory Pathway

Afferent pathway where signals arrive to the CNS.

Motor Pathway

Efferent pathway where signals exit the CNS.

Cervical Plexus

Spinal nerve network from $C1-C5$ that includes the phrenic nerve.

Phrenic Nerve

Nerve arising from $C3-C5$ that innervates the diaphragm.

Brachial Plexus

Spinal nerve network from $C5-T1$ containing upper limb nerves.

Lumbar Plexus

Spinal nerve network from $L1-L4$ containing femoral and tubular nerves.

Sacral Plexus

Spinal nerve network from $L4-S4$ containing the sciatic nerve.

Cranial Nerve I

Olfactory nerve responsible for the sensory function of smell.

Cranial Nerve II

Optic nerve responsible for the sensory function of vision.

Cranial Nerve III

Oculomotor nerve responsible for motor eye movement and pupil constriction.

Cranial Nerve IV

Trochlear nerve responsible for motor control of the superior oblique muscle.

Cranial Nerve V

Trigeminal nerve responsible for both face sensation and chewing.

Cranial Nerve VI

Abducens nerve responsible for motor control of the lateral rectus muscle.

Cranial Nerve VII

Facial nerve responsible for both facial expression, salivation, and taste for the anterior $\frac{2}{3}$ of the tongue.

Cranial Nerve VIII

Vestibulocochlear nerve responsible for the sensory functions of hearing and balance.

Cranial Nerve IX

Glossopharyngeal nerve responsible for both taste for the posterior $\frac{1}{3}$ of the tongue, swallowing, and salivation.

Cranial Nerve X

Vagus nerve responsible for both parasympathetic control to organs and taste at the epiglottis.

Cranial Nerve XI

Accessory nerve responsible for motor control of the SCM and trapezius.

Cranial Nerve XII

Hypoglossal nerve responsible for motor control of tongue movement.

Direct Motor Pathways

Pyramidal tracts responsible for conscious movement.

Lateral Corticospinal Tract

Direct motor pathway for skilled limb movement that decussates in the medulla.

Anterior Corticospinal Tract

Direct motor pathway for axial muscles and posture that decussates in the spinal cord.

Corticobulbar Tract

Direct motor pathway for face and neck muscles via cranial nerves; does not enter the spinal cord.

Indirect Motor Pathways

Extrapyramidal tracts responsible for reflexive or subconscious movement.

Rubrospinal Tract

Indirect motor pathway regulating flexor tone of limbs.

Tectospinal Tract

Indirect motor pathway for reflexive head and eye movement in response to sound or light.

Vestibulospinal Tract

Indirect motor pathway maintaining balance during standing and walking.

Reticulospinal Tract

Indirect motor pathway regulating posture and balance.

Sympathetic Division

Fight or flight division from $T1-L2$; increases HR, dilates pupils, and decreases digestion and urination.

Parasympathetic Division

Rest and digest division (CN III, VII, IX, X and $S2-S4$); decreases HR, constricts pupils, and increases digestion and urination.

Nicotinic Receptors

Cholinergic receptors found in ganglia that are always excitatory.

Muscarinic Receptors

Cholinergic receptors found at parasympathetic effectors that can be excitatory or inhibitory.

Alpha 1 Receptors

Adrenergic receptors responsible for vasoconstriction.

Alpha 2 Receptors

Adrenergic receptors responsible for inhibitory feedback.

Beta 1 Receptors

Adrenergic receptors that increase heart rate and contractility.

Beta 2 Receptors

Adrenergic receptors responsible for bronchodilation and vasodilation.

Mechanoreceptors

Sensory receptors that detect pressure, stretch, and vibration.

Thermoreceptors

Sensory receptors that detect temperature.

Nociceptors

Sensory receptors that detect pain.

Chemoreceptors

Sensory receptors that detect chemicals, $CO_2$, taste, and smell.

Photoreceptors

Sensory receptors that detect light, specifically rods and cones.

Proprioceptors

Sensory receptors in muscles, tendons, and joints that detect body position.

Bradykinin

Pain chemical that directly stimulates neurons.

Histamine

Chemical that causes vasodilation and increases capillary permeability.

Prostaglandins

Chemicals that increase pain sensitivity and cause inflammation.

Substance P

Pain neurotransmitter that continues the pain signal.

Inflammation

Condition characterized by pain, swelling, redness, heat, and loss of function.

Hyperesthesia

Term for increased sensitivity.

Hypoalgesia

Term for decreased pain sensitivity.

Analgesics

Drugs, such as NSAIDs, that block prostaglandins.

Anesthetics

Drugs that block the propagation of action potentials.

Opioids

Drugs that block Substance P.

Sclera

The white of the eye; provides protection.

Choroid

The vascular layer of the eye that absorbs light.

Retina

Layer of the eye containing photoreceptors (rods and cones).

Cornea

Transparent part of the eye that allows light entry.

Iris

Structure that controls pupil size.

Lens

Structure that focuses light.

Ciliary Muscles

Muscles that change the shape of the lens.

Optic Disc

The blind spot of the eye where no photoreceptors are present.

Fovea Centralis

Area of sharpest vision with the highest density of cones.

Rods

Photoreceptors used for dim light and peripheral vision; contains rhodopsin.

Cones

Photoreceptors used for color vision and sharp detail; contains photopsins.

Myopia

Nearsightedness caused by an eyeball that is too long.

Hyperopia

Farsightedness caused by an eyeball that is too short.

Presbyopia

Decreased accommodation caused by an aging lens.

Cataracts

Condition characterized by a cloudy lens.

Amblyopia

A condition commonly known as 'lazy eye'.

Tympanic Membrane

The eardrum; vibrates with sound waves.

Malleus

The first ossicle of the middle ear.

Incus

The second ossicle of the middle ear.

Stapes

The third ossicle; vibrates on the oval window.

Cochlea

The organ of hearing.

Semicircular Canals

Structures in the inner ear that detect rotational movement.

Oval Window

Site where sound enters the inner ear.

Round Window

Structure that acts as a pressure release for the inner ear.

Basilar Membrane

Membrane in the cochlea that vibrates with sound.

Tectorial Membrane

Structure that bends hair cells in the cochlea.

Hair Cells

Sensory cells that detect sound and release glutamate.

Static Equilibrium

Linear movement detection utilizing the utricle, saccule, and otoliths.

Dynamic Equilibrium

Rotational movement detection utilizing the semicircular canals.

Conductive Hearing Loss

Hearing loss caused by a problem in the middle ear.

Neural Hearing Loss

Hearing loss caused by damage to hair cells.

Tinnitus

A sensation of ringing in the ears.

Somatic Reflex

Reflex involving skeletal muscle.

Autonomic Reflex

Reflex involving smooth/cardiac muscle and glands.

Ipsilateral Reflex

Reflex that occurs on the same side as the stimulus.

Contralateral Reflex

Reflex that occurs on the opposite side of the stimulus.

Intrinsic Reflex

A reflex an individual is born with.

Learned Reflex

A reflex acquired through experience.