chapter 14

what is the nervous system organization

sensory receptors → afferent nerves→brain and spinal cord (CNS)→efferent nerves → somatic and autonomic system

from somatic system → skeletal nerves (effectors (PNS))

from autonomic system → sympathetic and parasympathetic division → both to smooth muscle glands (effectors (PNS))

what are the neurons in afferent nerves

sensory neurons

what are the neurons in efferent nerves

motor neurons

function of afferent nerves

carry sensory information to the CNS

function of efferent nerves

carry motor function information to the body form the CNS

what are the neurons for the sensory pathway

first-order neuron

second-order neuron

third-order neuron

how many neurons does hearing have

four

function of first-order neuron

detects the stimulus

function of second order neuron

receives the signal from the first-order neuron and relays it to third order neurons

function of the third order neuron

carries the signal from the thalamus (in most cases) to the primary somatosensory cortex

where is the cell body of first oder neurons for spinal nerves

• in the dorsal root ganglion

where is the cell body of first oder neurons for cranial nerves

• in cranial nerve ganglia

where does the second order neuron most intersect/ decussate at

the medulla

where does conscious perception and integration of the sensory information begin

third order neuron

what are the two neurons for the motor pathway

• Upper motor neuron (first-order motor neuron)

• Lower motor neuron (second-order motor neuron)

where is the cell body in the upper motor neuron

primary motor cortex

where is the cell body in the lower motor neuron

ventral horn of the spinal cord (or in the cranial nerve motor nuclei)

where does the axon descend through for spinal targets

through the corticospinal tract

where does the axon descend through for cranial nerve motor nuclei in the brainstem

corticobulbar tract that is most decussate at the medulla

where does the axon exit in the lower motor neuron and what does this form

the spinal cord via the ventral root and travels to the target skeletal muscle where it forms a neuromuscular junction

what is the somatic nervous system responsible for

our conscious perception of the environment and for our voluntary responses to that perception

what are the senses in our body

special and general senses

what are special senses

• senses that have a specific organ devoted to it (such as the eye, inner ear, tongue, or nose)

which nervous system are special senses apart of

somatic nervous system (as it is consciously perceived)

- olfaction (smell)

- gustation (taste)

- audition (hearing)

- equilibrium (balance)

- vision

what are general senses

senses that have no special organ

-somatosensation (touch, pressure, temperature, pain, proprioception)

- visceral senses (not conscious perception)

what do somatosensory mechanoreceptors in the skin sense

touch, pressure, temperature, and pain

what are mechanoreceptors deal with

sensations associated with the skin

where are proprioceptive receptors

near muscles and jointsf

function of Proprioceptive receptors

position sensing

types of Proprioceptive receptors

muscle spindles

golgi tendon organs`

where are muscle spindles

parallel to skeleton muscles

function of muscle spindle fibers

monitor muscle length and contraction

motor control

where is golgi tendon organs

along the tendons

function of golgi tendon organs

monitor tendon muscle and tendon tension

prevent over-contraction

what are classifications of sensory receptor cells based on

structure

location relative to the stimulus

how the cell transduces the stimulus into a neuron signal

what are classifications of sensory receptor cells based on: structure

anatomy of the cell that is interacting with the stimulus

they can have

• free nerve endings

• encapsulated endings

• specialized receptor cell

what are classifications of sensory receptor cells based on: location relative to the simulus

where the cell is located relative to the stimulus

• interoceptor

• exteroceptor

• proprioceptor

what are classifications of sensory receptor cells based on: How the cell transduces the stimulus into a neural signal:

convert stimulus to an action potential (stimuli such as movement, light, food)

• chemoreceptors

• osmoreceptors

• nociceptors

• mechanoreceptors

• thermoreceptors

• photoreceptors

what are free nerve endings

the unencapsulated dendrite of a sensory neuron to detect pain

what are nociceptors

sensory neurons with free nerve endings that sense pain

types of stimuli can nocioceptors detect

chemical, mechanical, or temperature

what is an exteroceptor

receptor near a stimulus in the external environment

what type of receptor is somatosensory receptors in the skin

exteroceptor

what is interoceptor

interprets stimuli from internal organs and issues

what type of receptor are the receptors that sense the increase in blood pressure in the aorta or carotid sinus

interoceptor

what is a proprioceptor

receptor that is near a moving part of the body, such as a muscle, that interprets the positions of the tissues as they move

what is audition (hearing)

the transduction of sound waves into a neural signal that is made possible by the structures of the ear

parts of the ear

external ear

middle ear

inner ear

what does the external ear contain

auricle, ear canal, and tympanic membrane

what does the middle ear contain

ossicles and is connected to the pharynx by the Eustachian tube

what does the inner ear contain

the cochlea and vestibule responsible for audition and equilibrium respectively

function of vestibule

equilibrium

function of cochlea

hearing

function of eustachian tube

• connect middle ear to pharynx

• helps maintain equal equilibrium on both sides of the tympanic membrane

what causes pain or swelling in the war

swelling due to ear infection or pressure difference during flying causes pain due to pressure difference

what are ear tubes

• ventilation tubes that have tiny cylinders (plastic or metal) that are surgically inserted into the tympanic membrane

• allow air to flow in and out of the middle ear to prevents negative pressure development and fluid build-up

  • membranes around eustachian tubes swell in colds and ear infections

how are sounds waves transmitted

• Amplified sound wave is picked up by the oval window causing pressure waves in the fluid of the scala vestibuli and scala tympani

• Organ of Corti creates nerve impulse

how are Hair cells at the base are activated

only by high frequencies in the cochlea

how are Hair cells at the apex are activated

only by low frequencies in the cochlea