Anatomy and Phyisology Chapter 13

Sensory Receptors

respond to changes in enviroment

Sensation

awareness in stimulus

Perception

meaning of stimulus

Mechanoreceptors

respond to touch, pressure, vibration, and stretch

Thermoreceptors

sensitive to changes in temperature

Photoreceptores

respond ti light energy

Chemoreceptors

respond to chemicals

Nociceptors

sensitive to pain-causing stimuli

Exteroceptors

receptors in skin for touch, pressure, pain, and temperature

Interoceptors

respond to stimuli arising in internal viscera and blood vessels

Proprioceptors

respond to sketch in skeletal muscles, tendons, joints, ligaments, and connective tissue coverings of bones and muscles

Simple Receptors of General Senses

tactile sensations, temperature, pain, and muscle sense

Receptors for Special Senses

vision, hearing, equilibrium, smell, taste

Somatosensory System

part of sensory system serving body wall and limbs

Receptors Level

sensory receptors

Circuit Level

processing in ascending pathways

Perceptual Level

processing in cortical sensory areas

Generating a Signal

the stimulus must excite a receptor, and the AP must reach CNS

Transduction

energy of stimulus is converted into graded potential called generator potential

First-Order Sensory

conduct impulses from receptor level

Second-Order Sensory

transmit umpulses to third order sensory neurons

Third-order Sensory

conduct impulses from thalamus to somatosensory cortex

Processing at Perceptual Level

interpretatioin of sensory input depends on specific location of target neruons in sensory cortex

Perceptual Detection

ability to detect a stimulus

Magnitude Estimation

intensity coded in frequency of impulses

Spatial Dicrimination

identifying site or pattern of stimulus

Feature Abstraction

identification of more complex aspects are several stimuulus properties

Quality Discrimination

ability to identify submidaities of a sensation

Pattern Recognition

recognition of familiar of significant patterns in stimuli

Pain Tlerance

genes help determine pain tolerance as well as response to pain medicatoins

Visceral and Referred Pain

stimulation of visceral organ receptors

Referred Pain

pain from one body region percieved as coming from different region

Endoneurium

loose connective tissue that encloses axons and their myelin sheaths

Perineurium

coarse connective tissue that bundles fibers inti fascicles

Epineurium

tough fibrous sheath around all fascicles to form the nerve

Mixed Nerves

contain both sensroy and motor fibers

Sensory (afferent) Nerves

impulses only toward CNS

Motor (efferent) Nerves

impulses only away from CNS

Somatic Afferent

muscle to brain

Somatic Efferent

brain to muscle

Visceral Afferent

organs to brain

Visceral Efferent

brain to organs

CNS Fibers

never regnerate

CNS Oligodendrocytes

growth-inhibiting proteins that prevent CNS fiber regeneration

Astrocytes

form scar tissue

Venteal Roots

contain motor (efferent) fibers from ventral horn motor neuron

Dorsal Roots

contain sensory (afferent) fibers from sensory neruons in dorsal root

Dorsal Ramus

smaller branch

Ventral Ramus

larger. branch

Meningeal Branch

tiny branch that reenters vertebral canal to innervate merges and bood vessels

Rami Communicantes

contain autonomic nerve fibers that join ventral rami in thoracic region

Phrenic Nerve

major motor and snesory nerve of diaphragm

Axiallry

innervates deltoid

Musculocutaneous

innervates biceps brachii

Median

innervates skin

Ulnar

supplies flexor carpi ulnaries

Radial

innervates essentially all extensor muscles

Femoral

innervates quadriceps and ski of anterior thigh

Obturator

passes through obturator foramem to innervate adductor muscles

Sciatic

innervates hamstring muscles

Inborn Reflex

rapid, involuntary, predictable

Learned

reflexe result from practice or repetition

Somatic Reflexes

activate skeletal muscle

Autonomic Reflexes

activate visceral effectors

Flexor Reflex

intiated by painful stimulus

Crosses Extensoe Reflex

occurs with flexor reflexes in weight bearing limbs to maintain balance

Superficial Reflexes

eliciated by gentle cutaneous stimulation of area