Chapter 13 Flashcards
Stimulus type
mechanoreceptors, thermorecptors, photoreceptors, chemoreceptors, nociceptors, exteroceptors, interceptors, proprioceptors
Sensory (afferent) nerves
impulses only toward CNS
motor (efferent) nerves
impulses only away from CNS
Ganglia
contain neuron cell bodies associated with nerves in PNS
Ganglia associated with afferent nerve fibers
contain cells bodies of sensory neurons
-dorsal root ganglia
Ganglia associated with efferent nerve fibers
contain autonomic motor neurons
-autonomic ganglia
CNS axons
most CNS fibers can never regenerate and CNS oligodendrocytes bear growth-inhibiting proteins that prevent CNS fiber regeneration
Form scar tissue at injury site
astrocytes
CNS axons treatment
neutralizing growth inhibitors, blocking receptors for inhibitory proteins, destroying scar tissue components
PNS axons
can regenerate if damage is not severe
Steps of PNS axon regeneration
- axon fragments and myelin sheaths distal to injury degenerate, degeneration spreads down axon
- macrophages clean dead axon debris, Schwann cells are stimulated to divide
- axon filaments grow through regeneration tube
- axon regenerates, and new myelin sheath forms
Olfactory nerves (I)
purely sensory (olfactory) function
Optic nerves (II)
purely sensory (visual) function
Oculomotor nerves (III)
function in raising eyelid, directing eyeball, constricting iris (parasympathetic), and controlling lens shape
Trochlear nerves (IV)
primarily motor nerve that directs eyeball
Trigeminal nerves (V)
convey sensory impulses from various areas of face (V1 and V2)
supply motor fibers for mastication (V3)
Abducens nerves (VI)
serves the lateral rectus eye muscle
Facial nerves (VII)
motor functions include facial expressions, parasympathetic impulses to lacrimal and salivary glands and sensory function (taste) from anterior two-thirds of tongue
Vestibulocochlear nerves (VIII)
hearing and equilibrium
Glosspharyngeal nerves (IX)
motor functions: innervate part of tongue and pharynx for swallowing and provide parasympathetic fibers to parotid salivary glands
sensory functions: fibers conduct taste and general sensory impulses from pharynx and posterior tongue, and impulses from carotid chemoreceptors and baroreceptors
Vagus nerves (X)
most motor fibers are parasympathetic fibers that help regulate activities of heart, lungs, and abdominal viscera
Accessory nerves (XI)
accessory nerves exit skull via jugular foramina to innervate trapezius and sternocleidomastoid muscles
Hypoglossal nerves (XII)
innervate extrinsic and intrinsic muscles of tongue that contribute to swallowing and speech
Pairs of cervical nerves
8 pairs
Pairs of thoracic nerves
12 pairs
Pairs of lumbar nerves
5 pairs
Pairs of sacral nerves
5 pairs
Pairs of tiny coccygeal nerves
1 pair
Phrenic nerve
major motor and sensory nerve diaphragm, major muscles for breathing
Components of reflex arc
- receptor
- sensory (afferent) neuron
- integration center
- motor (efferent) neuron
- effector
