Peripheral Nervous System Flashcards
What are the 2 divisions of the Autonomic nervous system
Sympathetic n.s
Parasympathetic n.s
What body structures make up the Peripheral nervous system
- Sensory receptors
- Cranial and spinal nerves
- Ganglia (neuron cell bodies)
Give examples: Sensory receptors
- Nociceptors (pain)
- Thermoreceptors (temp)
- Photoreceptors (light)
- Chemoreceptors (chemicals)
What is the structure of a Neuron from one end to the other as an impulse travels along
Dendrites- Cell body- Axon- Schwann cell- Axon terminal- Synaptic cleft
Structure of a Nerve
Define: Endoneurium
loose connective tissue that encloses individual axons and their myelin sheaths
Structure of a Nerve
Define: Perineurium
coarse connective tissue that bundles fibres into fascicles
Structure of a Nerve
Define: Epineurium
tough fibrous sheath around a nerve
What are the 3 layers of a Nerve
- Endoneurium (inner- encloses axons)
- Perineurium (middle- encloses endoneurium)
- Epineurium (outer- sheath enclosing perineurium)
How are nerves classified
according to the direction an impulse is travelling
What are the 3 classifications of nerves
Mixed nerves- both sensory and motor fibres (impulse to and from CNS)
Sensory nerves- afferent, impulse towards CNS
Motor nerves- efferent, impulse away from CNS
How many cranial nerves are there
12
Explain: Cranial nerve 2/ Optic nerve
is a sensory nerve from the eye
Explain: cranial nerve 8/ Vestibulocochlear nerve
is associated with the ear and is sensory for hearing and balance
How many spinal nerves are there
31 pairs
Define: Nerve Plexus
a cluster of interconnecting spinal nerves
How many pairs of nerves are in each section of the spine
Cervical- 8 pairs Thoracic- 12 pairs Lumbar- 5 pairs Sacral- 5 pairs Coccygeal- 1 pair
What are the 2 branches of the spinal nerves
Dorsal ramus- innervates the muscles and skin of the dorsal trunk
Ventral ramus- innervates muscles and structures of the upper and lower limbs, skin of the lateral and ventral surfaces of trunk
Define: Ganglia
clusters of neuron cell bodies outside the CNS
What are the 2 types of Ganglia
Dorsal root ganglia (sensory, somatic) Autonomic ganglia (motor, visceral)
Define: Reflex
is a rapid response to a specific stimulus
What are the 5 components of the reflex arc
Receptor Sensory neuron Integration center Motor neuron Effector
Which PNS is voluntary
Somatic nervous system
Which PNS is involuntary
Autonomic nervous system
What does the autonomic ganglion do
joins 2 neurons
Explain: Sympathetic nervous system
is responsible for the flight or fight response
- is activated when we are excited, exercising or there is an emergency
What are the physiological responses of the Sympathetic nervous system
- increased heart rate and BP
- pupils dilate
- sweating
Where does the Preganglionic neuron of the Sympathetic NS originate
in the thoracic and lumbar region
Where does the Preganglionic neuron of the Parasympathetic NS originate from
the cranial nerves (brain) and the sacral region
Explain: Parasympathetic nervous system
is the rest and digest response
- is activated to relax the individual and conserve bodily energy
What are the physiological responses of the Parasympathetic NS
- reduced heart rate and BP
- Increased salivation, urination, digestion and defaction
Which Ganglions Axons in the sympathetic and parasympathetic NS are myelinated and unmyelinated
Preganglionic axon- myelinated
Postganglionic axon- nonmyelinated
Acetylcholine is released by what neurons
Preganglionic neurons in the sympathetic and parasympathetic n.s
Norepinephrine is released by what neurons
Postganglionic neuron of the sympathetic nervous system
Somatic Nervous System
The neurotransmitter ACH targets what tissue
skeletal muscle
Autonomic Nervous System
The neurotransmitter ACH and NE target what tissue
Smooth muscle, cardiac muscle and glands
What is the visual pathway light takes in the eye
Cornea- Lens- Retina- Iris
What is the Hearing Pathway sound travels through the ear
outer ear (Pinna)- Tympanic membrane- Ossicles- Oval window- Choclea- Organ of corti- Cochlea nerve
What is the Neural Pathways for Hearing once sound has reached the cochlear
Cochlear nerve- Midbrain- Thalamus- Primary auditory cortex of temporal lobe
Explain: how Equilibrium is maintained
- Vestibule contains maculae
- Macule register change in head position
- Each semicircular canal has swelling called Ampulla
- Ampulla detect rotational movements
Sensory hairs of the Maculae and Ampulla are stimulated and impulses are transmitted to the brain via the vestibular nerve
What are the 3 components responsible for maintaining Equilibrium
- Vestibule
- Maculae
- Ampulla
What makes up the Peripheral nervous system
Somatic nervous system
Autonomic nervous system