Sensory Pathways and Somatic Senses Lecture Flashcards

Vocabulary flashcards covering sensory pathways, receptor subtypes, somatic sensory pathways, neural modulation, and inflammatory pain mechanisms.

Chemoreceptors

Sensory receptors that respond to chemical stimuli in the body, such as oxygen levels, hydrogen ions (pH), glucose, and sodium.

Mechanoreceptors

Sensory receptors that respond to tactile stimulation, including touch, pressure, vibration, body acceleration, and position of the body.

Photoreceptors

Receptors that detect photons of light permeating the external environment from sources like the sun or a screen.

Thermoreceptors

Sensory receptors that respond to thermal changes, including heat, cold, and varying degrees of temperature.

Nociceptors

Specialized sensory receptors that respond specifically to pain signals resulting from tissue damage.

Somatic Senses

All body senses that are not special senses (smell, sight, taste, hearing, equilibrium), including touch, proprioception, temperature, pain, and itch.

Direct Pathway

A sensory pathway, such as equilibrium signals traveling from the vestibule and semicircular canals directly to the cerebellum, that bypasses the thalamus.

Ganglia

A collection of nerve cell bodies located outside of the central nervous system (CNS).

Proscenium Corpuscle

A sensory receptor located deep within the skin that requires deep touch or pressure, such as a deep tissue massage, to activate.

Primary Sensory Neuron

The first sensory neuron in a pathway that receives a stimulus at its receptor and transmits an action potential toward the central nervous system.

Secondary Sensory Neuron

The sensory neuron that receives signals from a primary sensory neuron, decussates in either the medulla oblongata or spinal cord, and synapses in the thalamus.

Tertiary Sensory Neuron

The sensory neuron originating in the thalamus that projects and conveys signals directly to neurons in the primary somatic sensory cortex.

Decussation

The crossing over of neural pathways from one side of the body to the opposite side of the cerebral cortex, occurring in the spinal cord or medulla oblongata.

Lateral Inhibition

A mechanism where axon branches of a strongly stimulated secondary neuron inhibit adjacent secondary neurons, allowing the brain to perceive sharp contrast (such as a pinprick vs. broad pressure).

Receptor Field

The specific physical area in which a sensory receptor exhibits sensitivity to stimulation.

Sensory Adaptation

The process by which the perception of a constant, continuous stimulus decreases over time due to reduced receptor potential, decreased action potential frequency, or endocytosis of neurotransmitter receptors.

Phospholipase

An enzyme in the interstitial fluid that breaks down floating cell membrane phospholipids from injured tissue into arachnonic acid.

Arachnonic Acid

An intermediate substrate created from phospholipids during cell membrane injury that gets converted into leukotrienes or prostaglandins.

Lipogenase

An enzyme that acts on arachnonic acid to produce leukotrienes, which mediate inflammation.

Cyclooxygenase (COX)

An enzyme that acts on arachnonic acid to synthesize prostaglandins responsible for inflammation and pain.

Four Cardinal Signs of Inflammation

The standard physical responses to tissue injury: redness, heat, swelling, and pain.

Corticosteroids

An umbrella class of steroid molecules (including cortisol, hydrocortisone, and prednisone) that reduce inflammation by blocking phospholipase and cyclooxygenase enzymes.

Opioids

Analgesic medications (such as Vicodin and OxyContin) that decrease central pain perception by slowing or blocking neurotransmitter release from primary and secondary sensory neurons.