Final (God help me)

audition

the process where the ear converts sound waves into neural signals the brain interprets

What is the main energy transducer in the ear, and what does it do?

the hair cell in the cochlea, which converts mechanical vibrations (from sound waves moving fluid) into electrochemical signals (nerve impulses) sent to the brain

Role of the outer ear

collects sound and shapes frequency

selective enhancement

of certain auditory information while filtering out others, allowing for improved focus on relevant sounds.
Selective
enhancement of
certain frequencies
(1500-8000 HZ)
• 20 dB
enhancement at
2000 kHz

Outer ear gain

the natural amplification of sound by the pinna (outer flap) and ear canal, boosting frequencies, especially around 3 kHz, by about 10-15 dB to help us hear speech better

role of middle ear

matches the airborne acoustic signal
with the fluid medium of the cochlea
Deficits here= conductive hearing loss

Impedance matching

this is the transference of energy from the air of the middle ear to the inner ear fluid.

The hydraulic lever concentrates acoustic energy at the oval window and results from the 17- to 20-fold difference in vibratory surface of the tympanic membrane compared with the smaller area of the stapes footplate. This is thought to be the main impedance matching mechanism. The ossicular lever results from the long axis of the malleus being 1.3 times the length of the long process of the incus. A smaller contribution is made by the catenary lever. Both the outward convexity of the eardrum and radial orientation of collagen fibres in the tympanic membrane lead to a twofold amplification of sound pressure onto the umbo.

role of the inner ear

temporal and spectral analyses of
acoustic signal
• Auditory pathway-conveys and processes signal
Deficits here= sensorineural hearing loss

proprioception

Your body's ability to sense its own position, movement, and effort without looking.

vestibular system

The system for balance, spatial orientation, and head movement

spectral analysis

looks at what frequencies make up a signal (frequency domain), revealing pitch, timbre, or material composition, like analyzing notes in music or identifying chemicals

temporal analysis

examines how signals change over time (time domain), focusing on timing, duration, energy, or transitions, crucial for speech rhythm, event detection, or dynamic processes

traveling wave

is started on the basilar membrane. The ______ “breaks,” or reaches highest
amplitude at the place where it is processed

tonotopic arrangment

high frequencies are processed at the base (near the oval window) of the cochlea, while low frequencies are processed at the apex (far end)

• Stiffness: The membrane is stiffest at the base and most flexible (least stiff) at the apex.

• Width: The membrane is narrowest at the base and widest at the apex.

• Thickness: The membrane is thickest at the base and thinnest at the apex. 

shearing action

the crucial mechanical process in the cochlea where sound vibrations cause the basilar membrane and the overlying tectorial membrane to move in opposite directions, creating a shearing force that bends the stereocilia (tiny hairs) on the hair cells, opening ion channels, and converting sound (mechanical energy) into electrical signals for the brain.

excitation of outer vs inner hair cells

Inner hair cells (IHCs) act as the primary auditory receptors, converting sound vibrations into neural signals for the brain, while outer hair cells (OHCs) serve as active amplifiers, mechanically boosting quiet sounds and sharpening frequency detection through their unique ability to rapidly change length

ion transduction

how mechanical sound/motion becomes electrical signals via specialized hair cells, involving a unique ionic environment (high K+ in endolymph, high Na+ in perilymph) that allows bending stereocilia to open mechanosensitive channels (like TMC1), letting K+ and Ca2+ flow in, depolarizing the cell, releasing neurotransmitters, and triggering nerve signals to the brain

summating potential

a tiny, sustained electrical voltage (a DC shift) generated in the inner ear (cochlea) when hair cells convert sound vibrations into neural signals, reflecting the sound's intensity and duration

compound action potential

the summed electrical response of many auditory nerve fibers firing together, acting as a crucial diagnostic tool to assess the health and function of the auditory nerve, especially in cochlear implant (CI) users or for investigating deafness

low spontaneous rate

(high-threshold)
• Require high level of stimulation (in terms of signal intensity) to
fire)
• Respond to the higher end of our auditory range of signal
intensity

high spontaneous rate

(low-threshold)
• Respond to low signal intensities and display random firing even
when no stimuli is present

auditory pathway

• Cochlear Nucleus

  • First brainstem structure to receive auditory input from the auditory nerve (CN VIII).

  • Analyzes basic features of sound such as frequency, intensity, and timing.

• Superior Olivary Complex (SOC)

  • First site where information from both ears is integrated.

  • Plays a key role in sound localization, especially detecting differences in time and loudness between ears.

• Inferior Colliculus

  • Major auditory relay center in the midbrain.

  • Integrates auditory information and contributes to reflexive responses to sound and further sound localization.

• Medial Geniculate Body (MGB)

  • Auditory relay nucleus of the thalamus.

  • Organizes and sends auditory information to the auditory cortex.

• Cerebral Cortex (Primary Auditory Cortex)

  • Located in the temporal lobe.

  • Responsible for conscious perception and interpretation of sound, including speech and complex auditory processing.

central nervous system

The body's command center, comprising the brain and spinal cord, is responsible for integrating sensory information, processing it, and generating responses such as thoughts, movements, and organ functions

peripheral nervous system

The peripheral nervous system consists of all nerves outside the brain and spinal cord that carry information between the body and the central nervous system.

autonomic nervous system

your body's involuntary "autopilot," controlling essential functions like heart rate, breathing, digestion, and blood pressure without conscious thought, ensuring you stay alive and functional

somatic nervous system

controlling voluntary movements (like walking, talking) by connecting the brain and spinal cord to skeletal muscles, and also relays sensory info (touch, pain) from the body to the CNS

dendrites

receives messages from other cells

axon

passes messages away from the cell body to other neurons, muscles, or glands

axon terminal

transmit nerve signals from one neuron to the next cell by converting electrical signals into chemical signals

synapse

Space between two
nerve cells used for
transmission of
impulse

synaptic cleft

provide a tiny gap for chemical communication between neurons

vesicles

tiny bags that store neurotransmitters (chemical messengers) and transport them to the nerve ending (presynaptic terminal)

neurotransmitters

transmit messages between neurons, or from neurons to muscles.

myelin

Insulation surrounding
axons
• Promote impulse

nodes of ranvier

gaps in the myelin sheath on axons that act as "signal repeaters," allowing nerve impulses (action potentials) to "jump" from node to node

afferent

sensory cells

efferent

motor cells

gray matter

made of neuronal cell bodies, dendrites, and synapses, responsible for processing information, memory, emotion, and movement, forming the brain's outer cortex and inner nuclei

white matter

the inner brain tissue made of myelinated nerve fibers (axons) that transmit signals between brain regions, allowing for faster communication, learning, and complex skills

dura mater

the tough outermost membrane enveloping the brain and spinal cord.

arachnoid mater

a fine, delicate membrane, the middle one of the three membranes or meninges that surround the brain and spinal cord, situated between the dura mater and the pia mater.

subarachnoid space

the crucial area between the brain's pia mater and arachnoid mater layers, filled with cerebrospinal fluid (CSF) that cushions the brain, carries nutrients, and removes waste

pia mater

the delicate innermost membrane enveloping the brain and spinal cord.

cerebrospinal fluid

a clear liquid that bathes and protects the brain and spinal cord, acting as a shock absorber, delivering nutrients, removing waste, and maintaining a stable chemical environment for the central nervous system (CNS)

circle of willis

a vital arterial loop at the base of the brain, connecting the anterior (carotid) and posterior (vertebrobasilar) circulatory systems, allowing for collateral blood flow to protect against blockages

middle cerebral artery

a major blood vessel, a primary branch of the internal carotid artery, supplying oxygenated blood to the large lateral surface of the cerebral hemispheres, including motor/sensory areas, Broca's/ Wernicke's language centers, basal ganglia, and internal capsule

cerebrum

2 cerebral hemispheres
• Separated by longitudinal
fissure
• Connected by corpus
callosum

gyrus

bumps

sulcus

grooves

frontal lobe

is responsible for executive functions, including planning, decision-making, problem solving, personality, emotional regulation, voluntary movement, and speech production.

Important subareas:

• Primary Motor Cortex: Controls voluntary movements of the body.

• Premotor Cortex: Plans and coordinates movements before they occur.

• Supplementary Motor Area: Helps initiate and sequence complex movements.

• Broca’s Area: Responsible for speech production and expressive language.

• Prefrontal Cortex: Involved in attention, reasoning, impulse control, working memory, and social behavior.

parietal lobe

is responsible for processing and integrating sensory information, spatial awareness, and understanding body position in space.

Important subareas:

• Primary Somatosensory Cortex: Receives and processes touch, pain, temperature, and proprioception.

• Somatosensory Association Cortex: Integrates sensory input to recognize objects and interpret sensations.

• Posterior Parietal Cortex: Supports spatial perception, attention, and hand–eye coordination.

temporal lobe

is responsible for auditory processing, language comprehension, memory, and aspects of emotion.

Important subareas:

• Primary Auditory Cortex: Receives and processes basic sound information.

• Auditory Association Cortex: Interprets complex sounds, including speech and music.

• Wernicke’s Area: Responsible for language comprehension.

• Hippocampus: Involved in memory formation and learning.

• Amygdala: Plays a role in emotion and emotional responses.

occipital lobe

is responsible for visual processing, including the perception and interpretation of visual information.

Important subareas:

• Primary Visual Cortex: Receives and processes basic visual input such as light, color, and shape.

• Visual Association Cortex: Interprets visual information, allowing for object recognition, depth perception, and motion detection.

insular lobe

is involved in internal body awareness, emotion, taste, and integration of sensory, autonomic, and emotional information.

Important subareas:

• Primary Gustatory Cortex: Processes taste sensations.

• Anterior Insula: Plays a role in emotional awareness, empathy, and autonomic regulation.

• Posterior Insula: Involved in processing pain, temperature, and bodily sensations (interoception)

commissural

across
two hemispheres

association

within one
hemisphere
Short- within lobes
Long- between lobes

projection

between
different areas (i.e.,
cortex and lower brain or
spinal cord)

basal ganglia

A group of subcortical
nuclei
• Responsible for
background movement
and initiation of
movement
• Example of problems
here: Parkinson’s
Disease

limbic system

for regulating emotions (fear, anger, pleasure), motivation, long-term memory formation, learning, and survival instincts like feeding, fighting, and fleeing (the "5 Fs"). Key structures like the amygdala process fear and emotional memories, the hippocampus forms long-term memories, the hypothalamus manages stress responses (fight-or-flight) and hormones

midbrain

for relaying sensory info (vision, hearing) and controlling motor functions, eye movement, arousal, temperature, and pain

pons

acts as a crucial bridge, relaying signals between the cerebrum, cerebellum, and spinal cord, while controlling vital functions like breathing regulation, sleep cycles, and processing sensory/motor information for the face, hearing, balance, and chewing

medulla

controls vital involuntary functions like breathing, heart rate, and blood pressure, and manages reflexes such as swallowing, coughing, sneezing, and vomiting, while also relaying nerve signals between the brain and spinal cord

cerebellum

Little brain”
• Part of
metencephalon
• 2 hemispheres
• Postural stability
• Motor
learning/coordination

spinal cord

Aggregation of many
single nerve fibers into tracts
• Covered in meninges
• Begins at foramen magnum and ends at conus medullaris
• Nerves have sensory and motor component

reflex arc

Muscle spindles detect length
• If the muscle is stretched, that information is sent via afferent
components of the nerve to the dorsal root ganglion and to the
spinal cord
• Those fibers synapse with the lower motor neuron (efferent
pathway) and the neuron then innervates the muscle that was
stretched

spinal nerves

Dorsal and ventral roots
All are mixed afferent,
efferent

cranial nerves

1. Olfactory (I): Smell

2. Optic (II): Vision

3. Oculomotor (III): Eye movement, blinking, pupil control

4. Trochlear (IV): Up/down eye movement (superior oblique)

5. Trigeminal (V): Facial sensation, jaw muscles (mastication)

6. Abducens (VI): Lateral eye movement (side-to-side)

7. Facial (VII): Facial expressions, taste, some glands

8. Vestibulocochlear (VIII): Hearing and balance

9. Glossopharyngeal (IX): Taste, swallowing, salivary glands

10. Vagus (X): Heart rate, digestion, voice, swallowing

11. Accessory (XI): Neck and shoulder muscle movement

12. Hypoglossal (XII): Tongue movement (speech, swallowing) 

dysarthria

a motor speech disorder caused by neurological damage affecting the muscles for speech

apraxia

A neurological condition where the brain can't properly plan or sequence movements for tasks, despite the person knowing what to do and having normal muscle strength

aphasia

inability (or impaired ability) to understand or produce speech, as a result of brain disease or damage.

ischemic stroke

happens when a blood vessel in the brain gets blocked, cutting off oxygen and nutrients, causing brain cells to die rapidly; it's the most common type of stroke, often caused by clots from plaque buildup

hemorrhagic stroke

a medical emergency where a blood vessel in or around the brain ruptures, causing bleeding into brain tissue, increasing skull pressure, and killing brain cells, often from uncontrolled high blood pressure, aneurysms

benign tumor

a non-cancerous growth of abnormal cells that doesn't invade nearby tissues or spread (metastasize) to other body parts

malignant tumor

a cancerous growth where abnormal cells multiply uncontrollably, invade nearby tissues, and can spread (metastasize) to distant parts of the body through the bloodstream or lymphatic system

penetrating brain injury

refers to any injury that breaches the skull and protective barriers of the brain

closed brain injury

happens when a strong blow to the head makes the brain shake, bruise, swell, or tear inside the skull, without breaking the skull itself

focal damage

damages a specific area (like a bruise or bleed) from direct impact, causing localized symptoms

diffuse damage

injury spreads damage widely (like shearing of axons),