Anatomy 5th exam

General senses

Senses distributed throughout the body (touch

Special senses

Senses localized to specific organs (vision

Steps required for sensation

Stimulus → receptor activation → sensory impulse → interpretation in brain

Three classes of sensory receptors

Exteroceptors (external)

Five tactile sensations

Touch

Cold receptors

Respond to decreasing temperature; located superficially; more numerous

Warm receptors

Respond to increasing temperature; located deeper; fewer in number

Fast pain

Sharp

Slow pain

Dull

Superficial pain

Pain from skin and surface tissues

Deep pain

Pain from muscles

Visceral pain

Pain from internal organs; often poorly localized

First-order neuron

Neuron that carries sensory input from receptor to CNS

Second-order neuron

Neuron that carries input from spinal cord/brainstem to thalamus

Third-order neuron

Neuron that carries input from thalamus to cerebral cortex

Precentral gyrus

Primary motor cortex (controls voluntary movement)

Postcentral gyrus

Primary sensory cortex (receives sensory input)

Homunculus

Map of body representation in cortex; larger areas = more sensory/motor control

Two components of sleep

NREM sleep and REM sleep

Stages of NREM sleep

Stage 1 (light)

Neurons inhibited during sleep

Reticular activating system neurons

Autonomic changes during sleep

Sympathetic decreases; parasympathetic increases

Heart rate during sleep

Decreases

Blood pressure during sleep

Decreases

Immediate memory

Lasts seconds; limited capacity

Short-term memory

Lasts seconds to minutes

Long-term memory

Lasts days to years; large capacity

Alzheimer's disease

Progressive memory loss; beta-amyloid plaques and neurofibrillary tangles

Parkinson's disease

Loss of dopamine neurons; tremors

Huntington's disease

Genetic disorder; uncontrolled movements and cognitive decline

Pinna

Outer ear; collects sound waves

External auditory canal

Conducts sound to tympanic membrane

Tympanic membrane

Eardrum; vibrates with sound waves

Auditory ossicles

Malleus (hammer)

Oval window

Membrane where stapes transfers vibrations into inner ear

Round window

Relieves pressure in cochlea

Semicircular canals

Detect rotational movement

Vestibule

Detects linear acceleration and head position

Cochlea

Contains receptors for hearing

Scala vestibuli

Upper chamber of cochlea; contains perilymph

Scala tympani

Lower chamber; contains perilymph

Scala media

Middle chamber; contains endolymph and organ of Corti

Perilymph

Fluid similar to extracellular fluid in cochlea

Endolymph

Fluid high in potassium inside scala media

Organ of Corti (Spiral organ)

Sensory organ for hearing; contains hair cells

Function of hair cells

Convert mechanical vibrations into nerve signals

Muscles protecting ear

Tensor tympani and stapedius; reduce vibration from loud sounds

Sound wave properties

Frequency (pitch) and amplitude (loudness)

Equilibrium (balance)

Controlled by vestibular apparatus (semicircular canals + vestibule)

Static equilibrium

Head position relative to gravity

Dynamic equilibrium

Movement/rotation of head

Vision disorders

Myopia (nearsighted)

Cataracts

Clouding of lens

Glaucoma

Increased intraocular pressure damaging optic nerve

Hearing loss types

Conductive (middle ear issue)

Tinnitus

Ringing in ears

Anosmia

Loss of smell

Ageusia

Loss of taste

Mechanoreceptors

Receptors that respond to mechanical stimuli (touch

Thermoreceptors

Receptors that detect temperature changes

Nociceptors

Receptors that detect pain

Photoreceptors

Receptors that detect light (vision)

Chemoreceptors

Receptors that detect chemicals (taste

Phasic receptors

Rapidly adapting receptors; respond quickly then stop firing (detect changes)

Tonic receptors

Slowly adapting receptors; continue firing as long as stimulus is present

Sensory adaptation

Decreased response to constant stimulus over time

Dorsal column pathway

Carries fine touch

Spinothalamic pathway

Carries pain

Decussation

Crossing over of nerve fibers to opposite side of body

Thalamus Major

relay station for sensory information before reaching cortex

Primary sensory cortex

Located in postcentral gyrus; processes sensory input

Primary motor cortex

Located in precentral gyrus; initiates voluntary movement

Association areas

Interpret sensory input and coordinate responses

Reticular activating system

Regulates wakefulness and sleep cycles

REM sleep

Rapid eye movement sleep; dreaming occurs; brain activity increases

Stage 1 NREM sleep

Light sleep; transition between wakefulness and sleep

Stage 2 NREM sleep

Moderate sleep; body temperature drops

Stage 3 NREM sleep

Deep sleep; hardest to wake from

Dopamine

Neurotransmitter important for movement control (reduced in Parkinson's)

Beta-amyloid plaques

Protein accumulations found in Alzheimer's disease

Neurofibrillary tangles

Twisted protein fibers inside neurons in Alzheimer's

Basal nuclei

Brain structures involved in movement control (affected in Parkinson's and Huntington's)

Chorea

Involuntary jerky movements seen in Huntington's disease

Cochlear duct

Another name for scala media; contains organ of Corti

Basilar membrane

Vibrates in response to sound; location of hair cells

Tectorial membrane

Structure that bends hair cells during sound vibration

Hair cell stereocilia

Bend in response to movement; trigger nerve impulses

Pitch determination

Determined by location of vibration along basilar membrane

Loudness determination

Determined by amplitude of sound wave

Utricle

Detects horizontal acceleration (linear movement)

Saccule

Detects vertical acceleration

Macula

Receptor region in utricle and saccule for static equilibrium

Crista ampullaris

Receptor in semicircular canals for rotational movement

Cupula

Gel-like structure that bends with fluid movement in semicircular canals

Endolymph movement

Stimulates hair cells for balance and hearing

Myopia

Nearsightedness; image focuses in front of retina

Hyperopia

Farsightedness; image focuses behind retina

Astigmatism

Irregular curvature of cornea/lens

Presbyopia

Age-related loss of near focusing ability

Conductive hearing loss

Problem transmitting sound through middle ear