Peripheral Nervous System Flashcards
SENSORY RECEPTOR
Specialized to respond to changes
(stimulus) in environment
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• Generate graded potentials that trigger action
potentials in sensory nerves (called transduction)
• Sensation (awareness of stimulus) and Perception
(interpretation of stimuli) occur in brain
• 1 sensory neuron only carries info for 1 sensation
• Sensory receptor classification based on
• Stimulus detected
• Location of activating stimulus
• Structural complexity
respond to touch, pressure, stretch (also hearing and balance)
Mechanoreceptors
respond to temp changes
Thermoreceptors
respond to light energy
Photoreceptors
respond to chemicals in solution (taste, smell, oxygen)
Chemoreceptors
respond to pain
Nociceptors
respond to pressure and stretch; found in blood vessels: carotid arteries and aortic arch
Baroreceptors
respond to stimuli outside body so near
body surface
• Includes touch, pain, pressure, temperature and
special senses
Exteroceptors
respond to stimuli inside body (organs
and blood vessels)
Interoceptors
Monitors stretching of skeletal muscles for body
movement awareness
Proprioceptors
modified dendrite endings
• Free nerve endings
• Found mostly in epithelia or connective tissue
• Detect pain and extreme temperature
General receptors
Encapsulated endings
• Have connective tissue cap enclosing dendrite endings
• All are mechanoreceptors
• Found in skin, skeletal muscles, joints, tendon
General receptors
localized collections of different cells working
together to collect sensory data
• Include smell, taste, vision, hearing and balance
Special receptors
Bundles of axons covered by connective
tissue
NERVE COVERINGS
surrounds bundles of fascicles to form
nerve
Epineurium
surrounds bundles of axons
fascicles
Perineurium
surrounds axon (fiber)
Endoneurium
motor neuron (Lisa Simpson Model: single axon, multiple dendrites)
Multipolar
motor neuron (Lisa Simpson Model: single axon, multiple dendrites)
Bipolar
sensory neurons: touch and
stretch (hanger shape: one end dendrite, one end
axon terminal)
Unipolar
• Cranial – 12 pairs from brain
NERVES
sensory nerve for smell
I – Olfactory
sensory nerve for vision
II – Optic
motor for eye muscles and eyelid;
pupillary constriction; muscles to the lens
III – Oculomotor
motor for eye muscles
IV – Trochlea
largest nerve – mixed
• Sensory (touch, pain and temperature) to face
• Motor to mastication muscles (3 branches –
opthalmic, maxillary and mandibular)
V- Trigeminal
motor for eye muscles
VI – Abducens
mixed nerve
• Sensory – taste sensations anterior 2/3 of tongue
• Motor – facial expression, salivary and lacrimal glands (autonomic)
VII – Facial
mixed
• Sensory - hearing and balance (dominant)
• Very little motor – modifies hair cells
VIII - Vestibulocochlear
mixed
• Sensory - hearing and balance (dominant)
• Very little motor – modifies hair cells
VIII - Vestibulocochlear
mixed nerve
• Sensory – taste to posterior 1/3 of tongue; somatic sensations (touch, temp) from pharynx and tongue, monitors blood pressure, O2 and CO2 levels in carotid arteries
• Motor – elevates pharynx during swallowing; motor to parotid glands
Glossopharyngeal
mixed nerve –only one to extend past
shoulders
• Sensory – taste to epiglottis; somatic sensation from
epiglottis and pharynx, monitors blood pressure and
O2 and CO2 levels for respiration rate in aortic arch,
monitors organs in thorax and abdomen
• Motor – swallowing, coughing, voice production,
peristalsis, slows heart rate
X – Vagus
motor nerve for moving shoulders and head (SCM and trapezius)
XI – Accessory
motor nerve for tongue
movement (speech)
XII – Hypoglossal
