BIO 2450 Exam 4

Epineurium

Connective tissue layer surrounding entire nerve

Perineurium

Connective tissue layer surrounding a fascicle (bundle of axons)

Endoneurium

Connective tissue layer surrounding individual axon

Fascicle

Bundle of nerve fibers within a nerve

Dura mater

Outer tough meningeal layer protecting brain and spinal cord

Arachnoid mater

Middle web-like meningeal layer

Pia mater

Inner delicate meningeal layer attached to brain surface

Central canal

CSF-filled channel at center of spinal cord

Posterior gray horn

Region of spinal cord gray matter containing sensory neuron processing

Anterior gray horn

Region of spinal cord gray matter containing motor neuron cell bodies

Lateral gray horn

Region containing autonomic neurons (thoracic/lumbar only)

Gray commissure

Connects left and right sides of spinal cord gray matter

Dorsal column pathway

Carries fine touch, vibration, proprioception; crosses in medulla

Spinothalamic pathway

Carries pain, temperature, crude touch; crosses in spinal cord

Spinocerebellar pathway

Carries subconscious proprioception to cerebellum; does not cross

Dorsal root ganglion

Contains sensory neuron cell bodies entering spinal cord

Ventral root

Contains motor neuron axons leaving spinal cord

Phrenic nerve

Innervates diaphragm; arises from C3–C5

Monosynaptic reflex

Reflex involving only sensory and motor neuron (example: patellar reflex)

Polysynaptic reflex

Reflex involving interneurons (example: withdrawal reflex)

Choroid plexus

Structure that produces cerebrospinal fluid

CSF functions

Cushions brain, removes waste, transports nutrients, stabilizes environment

Cerebrum

Responsible for conscious thought, voluntary movement, memory, sensation

Cerebellum

Coordinates movement, posture, balance, motor learning

Thalamus

Major sensory relay station to cerebral cortex

Hypothalamus

Maintains homeostasis and controls pituitary gland

Brainstem

Includes midbrain, pons, medulla; controls vital functions

Pons

Regulates breathing rhythm and sleep

Medulla oblongata

Controls heart rate, breathing, blood pressure

Limbic system

Controls emotion, behavior, memory

Hippocampus

Important for memory formation

Reticular activating system

Controls alertness and consciousness

Corpus callosum

Connects left and right cerebral hemispheres

Central sulcus

Separates frontal and parietal lobes

Longitudinal fissure

Separates left and right cerebral hemispheres

Primary motor cortex

Controls voluntary skeletal muscle movement

Primary somatosensory cortex

Receives touch sensation

Visual cortex

Processes vision in occipital lobe

Auditory cortex

Processes sound in temporal lobe

Association areas

Integrate and interpret sensory information

Basal nuclei

Help regulate movement coordination

Frontal lobe

Responsible for planning, movement, personality

Parietal lobe

Processes somatic sensory information

Temporal lobe

Processes hearing and memory

Occipital lobe

Processes vision

Alpha waves

Brain waves during relaxed wakefulness

Beta waves

Brain waves during alert mental activity

Theta waves

Brain waves during light sleep

Delta waves

Brain waves during deep sleep

Otolith

Calcium crystals detecting gravity and linear movement

Otic

Relating to the ear

Optic

Relating to the eye or vision

Myopia

Nearsightedness; image forms in front of retina

Hyperopia

Farsightedness; image forms behind retina

Keratotomy

Surgical reshaping of cornea to correct vision

Lacrimal glands

Produce tears

Tympanic membrane

Eardrum; vibrates with sound waves

Oval window

Membrane receiving vibrations from stapes into cochlea

Round window

Relieves pressure within cochlea

Vestibular system

Responsible for balance and equilibrium

Olfactory receptors

Modified bipolar neurons detecting smell in olfactory epithelium

Olfactory pathway

Receptors → olfactory nerve → olfactory bulb → olfactory cortex

Olfactory receptor replacement

Regenerated about every 30–60 days

Nasal conchae function

Warm, humidify, and filter air; enhance smell detection

Animals stronger smell reason

Larger olfactory epithelium and more receptors

Smell interpretation

Brain recognizes odor based on receptor activation patterns

Taste receptors location

Located within taste buds

Taste bud receptor count

Each taste bud contains about 50–100 receptor cells

Taste receptor replacement rate

Replaced about every 10 days

Fungiform papillae

Taste papillae located mostly on anterior tongue

Circumvallate papillae

Large papillae located at posterior tongue

Foliate papillae

Papillae located along sides of tongue

Filiform papillae

Papillae lacking taste buds; provide texture

Five taste sensations

Sweet, sour, salty, bitter, umami

Gustducin

G-protein used in sweet, bitter, umami taste detection

Salt and sour detection

Detected via direct ion channels

Sweet bitter umami detection

Detected via G-protein-coupled receptors

Percent taste dependent on smell

Approximately 80 percent

Accessory eye structures

Include lacrimal glands and rectus muscles

Three tunics of eye

Fibrous, vascular, neural layers

Fibrous tunic

Includes sclera and cornea

Vascular tunic

Includes choroid, iris, ciliary body

Neural tunic

Includes retina

Rods

Detect dim light; provide night vision

Cones

Detect color and sharp detail

Cataract

Clouding of the lens causing blurred vision

Parasympathetic pupil constriction nerve

Oculomotor nerve (CN III)

Hair cells stimulation surface

Hair cells contact tectorial membrane

Sound transmission pathway

Ear canal → tympanic membrane → ossicles → oval window → cochlea → hair cells → CN VIII

Auditory ossicles

Malleus, incus, stapes

Stapes function

Presses on oval window transmitting vibration to cochlea

Vestibule

Detects head position relative to gravity

Semicircular canals

Detect rotational movement of head

Otolith function

Detect linear acceleration and gravity

Endocrine glands

Release hormones directly into bloodstream

Peptide hormones

Derived from amino acids; bind membrane receptors; use second messengers

Steroid hormones

Derived from cholesterol; bind intracellular receptors; alter gene expression

Amino acid derivative hormones

Include epinephrine, norepinephrine, thyroid hormones, melatonin

First messenger

Hormone outside target cell

Second messenger

Intracellular signal molecule such as cAMP