Physiology of Sensory, Motor, and Autonomic Systems

A set of vocabulary flashcards covering human physiology, specifically sensory receptors, neural pathways, motor control mechanisms, sleep/wake regulation, and physiological adaptations to exercise and environment.

Parallel circuits

A neural circuit where a presynaptic neuron is connected to parallel postsynaptic neurons, such as in the retina for processing different visual stimulus properties.

Exteroception

The detection and processing of information from the external environment.

Proprioception

The detection and processing of information from the musculoskeletal system regarding position and movement.

Interoception

The detection and processing of information from the internal body environment via visceral organs.

Mechanoreceptors

Sensory receptors that respond to mechanical pressure or distortion.

Ruffini endings

Encapsulated grape-like structures oriented parallel to the skin surface that detect stretching, have large receptive fields, and are slow adapting.

Meissner’s corpuscle

Receptors oriented perpendicular to the skin, densely packed in fingertips, with small receptive fields that are rapidly adapting and important for texture detection.

Pacinian corpuscle

A nerve terminal wrapped in a lamellate capsule that is very sensitive to vibrations and rapid skin indentation, featuring a large receptive field and rapid adaptation.

TRPM8 channel

A channel sensitive to temperature ranges of $10-35^∘\text{C}$ and activated by ligands like menthol to evoke a cooling sensation.

Triple response

A physiological skin reaction to injury characterized by vasodilation, reddening, and swelling.

Primary pain (Hyperalgesia)

A state of increased pain sensitivity that occurs directly within damaged tissue.

Dermatomal rule

A principle stating that a site on the skin is innervated by nerves arising from the same spinal cord segment as those innervating specific visceral organs.

Antinociceptive system

The brain's endogenous pain suppression system, involving the periaqueductal gray matter, nucleus raphe magnus, and enkephalinergic neurons.

Organ of Corti

The sensory organ of hearing located within the cochlea, containing hair cells and the basilar membrane.

Tip Links

Protein structures that link stereocilia to each other and control the opening of ion channels during auditory transduction.

Cochlear microphonic potential

The electrical changes resulting from oscillating depolarization and hyperpolarization in auditory hair cells.

Tonotopic map

A spatial mapping of sound frequencies where high frequencies are recorded at the base of the basilar membrane and low frequencies at the apex.

Accommodation

The process by which the ciliary muscles change the shape of the lens to focus on objects at various distances.

Emmetropia

The normal refractive condition of the eye where parallel light rays are focused accurately on the retina when accommodation is relaxed.

Rhodopsin

The main photopigment in human rods consisting of an opsin membrane protein and a retinal molecule.

Scotopic vision

Vision during low light conditions (nightlight) involving only rods, characterized by no color perception and low discrimination ability.

Minimum angle of resolution (MAR)

The minimum subtended visual angle ($\text{assumed to be } 1\text{ minute of arc}$) at which two points can still be discriminated.

Anosmia

The medical term for the lack of a sense of smell.

Glomeruli (Olfactory)

Synaptic clusters in the olfactory bulb where approximately $1000$ olfactory receptors converge onto a single mitral cell.

Circumvallate papillae

The largest but fewest taste papillae, located at the end of the tongue and innervated by CN IX.

Tonic movements

Long-lasting contractions of skeletal (axial) muscles used to maintain posture and equilibrium.

Phasic movements

Rapid, wide-ranged contractions of distal skeletal muscles used for locomotion and voluntary movements.

Muscle spindles

Intrafusal fibers distributed among extrafusal fibers that act as stretch receptors to detect changes in muscle length.

Golgi tendon reflex

The inverse stretch reflex where muscle contraction causes relaxation of the same muscle via Ib-afferent nerves and inhibitory interneurons.

Otolith organs

The utricle and saccule, which detect linear acceleration and gravitational forces using calcium carbonate crystals called otoconia.

Nystagmus

A reflex eye movement produced by head rotation, consisting of a slow component (maintaining gaze) and a rapid component (jumping to a new position).

Basal ganglia

Deep nuclei of the telencephalon (including the caudate, putamen, and globus pallidus) that influence the motor cortex via direct and indirect pathways.

Synergy

The regulation of the rate, range, force, and direction of movements, a function primarily controlled by the cerebellum.

Electroencephalogram (EEG)

A recording of the spontaneous graded synaptic potentials of the cerebral cortex picked up by electrodes on the skull.

Ascending Reticular Activating System (ARAS)

A network of neurons in the brainstem crucial for maintaining wakefulness and alertness by modulating cortical excitability.

Paradoxical sleep

Another name for REM sleep because the EEG shows beta waves typical of an awake, active state.

Ventrolateral preoptic nucleus (VLPO)

The anterior hypothalamus region considered the "switch" for sleep, using GABA and galanin to inhibit arousal regions.

Circadian rhythm

A biological rhythm roughly $24\text{ hours}$ in length, regulated by the suprachiasmatic nucleus (SCN).

Papez circuit

A neural circuit involving the amygdala, hippocampus, thalamus, and hypothalamus responsible for emotional expression and memory.

Declarative memory

Long-term "what" memories for facts and personal experiences that are fast and consciously recalled.

Habituation

A type of non-associative learning characterized by a loss of response due to repeated exposure to a non-painful stimulus.

ATP–PC system

An immediate energy system used for the first $10\text{ seconds}$ of activity that uses phosphocreatine to rapidly re-form ATP.

Oxygen debt

The repayment period after exercise where lactic acid is converted to pyruvic acid and O2 re-binds to myoglobin and hemoglobin.

Polycythemia

An adaptation to hypobaric conditions where the body increases red blood cell production to enhance O2-carrying capacity.

Diving reflex

A physiological response to hyperbaric conditions (diving) characterized by bradycardia, vasoconstriction, and spleen compression.