Chapter 13 Peripheral Nervous System Flashcards
specialized to respond to changes in the environment
-Activation results in graded potentials that trigger nerve impulses
Sensory Receptors
respond to touch, pressure, vibration, and stretch
Mechanoreceptors
sensitive to changes in temperature
thermoreceptors
respond to light energy (ex: retina)
photoreceptors
respond to chemical (ex: smell, taste, changes in blood chemistry)
chemoreceptors
sensitive to pain-causing stimuli (ex: extreme heat or cold, pressure)
nociceptors
responds to stimuli arising outside of body
- receptors in skin for touch, pressure, pain, and temp
- most special sense organs
extereceptors
responds to stimuli arising in internal viscera + blood vessels
- sensitive to chemical changes, tissue stretch, temp changes
- person is usually unaware of the changes, sometimes feels discomfort
interoceptors
tells us our body positions
- respond to stretch in skeletal muscles, tendons, joints, ligaments, and connective tissue covering bones and muscles
- informs brains of ones movement
proprioceptors
found throughout the body and monitor most sensory(tactile) information
Have either 1. Nonencapsulated (free) nerve endings or 2. Encapsulated nerve endings
simple receptors of the general senses
vision, hearing , equilibrium, smell, and taste
-all houses in complex, sense organs
receptors for special senses
- receptor level: sensory receptors
- circuit level: processing in ascending pathways
- perpetual level: processing in cortical sensory areas
levels of neural integration in sensory system
change in sensitivity in presence of constant stimulus
adaptation
sends signals at the beginning or end of stimulus
ex: receptors for pressure, touch, smell (leaning against a wall or putting clothes on)
Phasic receptors (fast adapting)
important in sending constant signals to make aware of pain or uncomfortableness
ex: nociceptors and most propioceptors
tonic receptors (slow adapting or not at all)
sensory info interpreted in the cerebral cortex
processing at the perceptual level
cordlike organ of PNS
bundle of myelinated or nonmyelinated peripheral axons enclosed by connective tissue
2 types cranial or spinal
Nerve
outside layer of tough fibrous sheath that encloses all fascicles to form nerve
epineurium
coarse connective tissue that bundles fibers into fascicles
perineurium
loose connective tissue that encloses axons and their myelin sheaths (Schwann cells)
endoneurium
impulses move towards CNS
Sensory (afferent) nerves
impulses only away from CNS
motor (efferent) nerves
mnemonic for cranial nerves
On occasion our trusty trucks acts funny very good vehicle anyhow
sensory(smell) can afferent impulses for sense of smell
I. olfactory nerves
sensory(vision) can afferent impulses for vision
II. optic nerve
motor, 4/6 of eye muscles
III. oculomotor nerves
motor, very top of eye muscles(pulley)
IV. trochlear nerves
both sensory and motor, includes branches of mandible, maxilla, and opthalmic
V. trigeminal nerves
motor, supplies muscle movement to later rectus
VI. Abducens nerves
sensory and motor (facial expressions)
VII. facial nerve
sensory (hearing and balance)
VIII. vestibulocochlear nerve
sensory (taste) and motor (tongue and throat)
IV. glossopharyngeal nerve
sensory (taste) and motor (heart, lungs liver, stomach, kidney, parasympathetic)
X. Vagus nerve
motor (sternocleidomastoid and trapezius control)
XI. accessory nerve
motor (tongue movement)
hypoglossal nerve
involuntary, predictable response to stimulus
ex: maintain posture, control visceral activates
can be modified by learning and conscious effort
Inborn (intrinsic) reflex: rapid
results from practice or repetition
ex: driving skills
Learned(acquired) reflexes
occur without direct involvement of higher brain center
brain is still advised reflex activity
spinal reflex
used to determine the condition of nervous system
stretch flexor, superficial reflexes
reflex assessments
to smoothly coordinate skeletal muscle, nervous system must receive proprioceptor input regarding:
length of muscle
amount of tension sent from tendon organs
stretch and tendon reflexes
clusters of neuron cell bodies in the peripheral nervous system
ganglia
bundles of neuron processes peripheral nervous systems
nerves
receptive (input) region of neurons
dendrites
excitable cells that emit a electrical signal
neurons
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