Unit 4.1: Sensory, Thermoregulation, Pain & Sleep

Comprehensive vocabulary flashcards covering thermoregulation, mechanisms of heat loss, hyperthermia, hypothermia, pain terminology and classifications, as well as sensory disorders of the eye and ear.

Thermoregulation

The body's ability to control and maintain body temperature.

Hypothalamus (in thermoregulation)

The main temperature control center of the body.

TRH and TSH

Hormones that stimulate thyroid activity to assist in thermoregulation.

T4

A thyroid hormone that increases basal metabolic rate (BMR) and slowly increases heat production.

Epinephrine (in thermoregulation)

A hormone that causes vasoconstriction and increases basal metabolic rate (BMR) to produce and conserve heat.

Evaporation

A mechanism of heat loss where sweat evaporates from the skin and removes heat.

Vasodilation (in thermoregulation)

The widening of blood vessels near the skin surface, bringing warm blood closer to the surface so heat can escape.

Radiation (heat loss)

Heat loss that occurs without direct physical contact, such as sitting in a cold room.

Conduction (heat loss)

Heat loss that occurs through direct physical contact, such as lying on a cold floor.

Convection (heat loss)

Heat loss that occurs through moving air or water, such as a fan blowing on the skin.

Fever

A temporary increase in body temperature that occurs in response to pyrogens stimulating the hypothalamus and brainstem.

Pyrogens

Substances that trigger fever; they can be endogenous (originating from inside the body) or exogenous (originating from outside the body).

Hyperthermia

An abnormally high body temperature that occurs without the hypothalamus triggering the temperature increase or changing the hypothalamic temperature setting.

Heat Exhaustion

A heat-related condition typically caused by excessive sweating and water/electrolyte loss, characterized by weakness, fatigue, dizziness, headache, nausea, vomiting, muscle cramps, increased heart rate, and cool, pale, clammy skin.

Heat Stroke

A medical emergency resulting from the body's failure to regulate temperature, characterized by severe hyperthermia, hot skin, increased heart rate, and central nervous system alterations such as confusion, altered mental status, loss of consciousness, or seizures.

Hypothermia

A condition defined as a core body temperature falling below $35^\circ\text{C}$, leading to vasoconstriction, increased blood viscosity, shivering, and potential cellular rupture.

Nociceptive Pain

Pain resulting from the stimulation of pain receptors (nociceptors) by mechanical, thermal, or chemical stimuli.

Pain Threshold

The lowest intensity of stimulation that a person recognizes as painful.

Pain Tolerance

The greatest intensity of pain that an individual can endure.

Nociception

The physiological process of transmitting pain signals from peripheral tissues to the brain.

Afferent Fibres (pain pathway)

Nerve fibres that carry sensory and pain signals from peripheral tissues toward the central nervous system.

Somatosensory Cortex (pain pathway)

The cerebral cortical region that processes incoming sensory signals so pain can be consciously recognized.

Acute Pain

Sudden, short-term pain that functions as a protective warning mechanism against tissue injury and typically subsides once the painful stimulus is eliminated.

Somatic Pain

Well-localized pain originating from skin, muscles, bones, joints, or connective tissue.

Visceral Pain

Poorly localized pain originating from internal organs, often described as deep, aching, cramping, or pressure-like.

Referred Pain

Pain perceived at a location away from its actual origin due to convergence of sensory signals in the nervous system.

Chronic Pain

Persistent pain lasting longer than $3\text{ months}$, which can induce physiological adaptation as well as behavioral and psychological changes.

Neuropathic Pain

Pain caused by primary trauma or disease affecting nerves, resulting in abnormal pain signal processing.

Neuralgia

Pain that occurs along the specific distribution or pathway of a nerve.

Neuroma

A bundle of nerve tissue that can form following nerve injury or transection.

Phantom Limb Pain

Pain perceived in a missing limb following amputation, often linked to hyperactivity of peripheral nerves, scar tissue, or neuroma formation.

Cataracts

Clouding or opaqueness of the ocular lens caused by alterations in lens proteins, resulting in decreased visual acuity, blurred vision, and diminished color perception.

Glaucoma

A group of eye disorders involving impaired drainage of aqueous humor, increased intraocular pressure (IOP), and damage to optic nerve fibres, primarily causing peripheral vision loss first.

Open-Angle Glaucoma

The most common form of glaucoma where the drainage angle remains open but the trabecular meshwork is obstructed, leading to a gradual increase in IOP and slow, asymptomatic visual loss.

Closed-Angle Glaucoma

An ophthalmic emergency in which the iris moves forward against the cornea and physically blocks the drainage angle, causing rapid fluid accumulation, sudden high IOP, and pain.

Macular Degeneration

Degeneration of the macula within the retina that leads to progressive impairment or loss of central vision.

Dry AMD

The most frequent type of age-related macular degeneration, characterized by drusen deposition, atrophy of the retinal epithelial layer, loss of photoreceptors, and gradual central vision loss.

Wet AMD

An advanced form of age-related macular degeneration where fragile, abnormal blood vessels proliferate beneath the retina and macula, leaking fluid and causing rapid central vision decline.

Retinal Detachment

Separation of the retina from underlying tissue, frequently precipitated by vitreous liquefaction, causing flashes of light, floaters, and reduced retinal oxygen and nutrient supply.

Otitis Externa

Infection or inflammation of the external ear canal, commonly termed swimmer's ear, presenting with tenderness upon outer ear traction, pruritus, redness, swelling, and drainage.

Otitis Media

Infection or inflammation of the middle ear space, frequently seen in children, presenting with otalgia, fever, pressure/fullness, and diminished hearing.

Presbycusis

Age-related sensorineural hearing loss caused by the degeneration of cochlear hair cells and auditory neurons, primarily hindering the perception of high-frequency sounds and speech.