Chapter 15 - Neural Integration

what are sensory receptors?

specialized cells that monitor specific conditions in the body or the external environment, when stimulated, information is sent to the CNS from the PNS

what is a sensory pathway?

nerves deliver somatic and visceral sensory information to their final destinations inside the CNS

what does the somatic motor portion of the efferent division do?

controls peripheral effectors

what are some general senses?

temperature, pain, touch, pressure, vibration, proprioception

what is sensation?

the arriving of information from these senses

what is perception?

conscious awareness of a sensation

what do sensory receptors do?

interface between the nervous system and the environment and detects a stimulus

what happens after the sensory receptor detects a stimulus?

transduction occurs

what is transduction?

when the sensory receptor translates the stimulus into an action potential that is conducted to the CNS

what happens when there is no transduction?

there is no detectable stimulus, meaning that the stimulus is still there but our receptors do not detect it

what is receptor specificity?

each receptor has a characteristic sensitivity

• i.e. touch receptors are very sensitive to pressure but relatively insensitive to chemical stimuli

what is the receptive field?

the area that is monitored by a single receptor cell

what happens when the receptor field is too large?

it is more difficult to localize a stimulus

what is adaptation?

reduction in the sensitivity of a constant stimulus, your nervous system quickly adapts to stimuli that are painless and constant

what are tonic receptors?

• always active

• show little peripheral receptors

• are slow-adapting receptors

• remind you of an injury long after the initial damage has occurred

what are phasic receptors?

• normally active

• become active for a short time whenever a change occurs

• provides information about the intensity and rate of change of stimulus

• are fast-adapting receptors

what are the classes of sensory receptors

• exteroceptors

• proprioceptors

• interoceptors

what are exteroceptors?

provides information about the external environment

what are proprioceptors?

reports the positions of skeletal muscles and joints (posture)

what are interoceptors?

monitor visceral organs and functions

what are the 4 general sensory receptors?

• nociceptors (pain)

• thermoreceptors (temperature)

• mechanoreceptors (physical distortion)

• chemoreceptors (chemical concentration)

what is a nociceptor?

responds to pain

• has a large receptive field

where are nociceptors found?

• in the superficial portions of the skin

• in joint capsules

• within the periostea of bones

• around the walls of blood vessels

do nociceptors have phasic receptors or tonic receptors?

tonic receptors

what are thermoreceptors?

receptors that detect temperature

where are thermoreceptors found?

• the dermis

• skeletal muscles

• the hypothalamus

do thermoreceptors have phasic receptors or tonic receptors?

phasic receptors

what are mechanoreceptors?

receptors that are sensitive to stimuli that distort their plasma membrane

where are mechanoreceptors found?

mechanically-gated ion channels

what are the 3 classes of mechanoreceptors?

1. tactile receptors

2. baroreceptors

3. proprioceptors

what do tactile receptors do?

provides the sensation of touch, pressure, and vibration

what do baroreceptors do?

detects changes in pressure

what do proprioceptors do?

monitors the position of joints and muscles

what do chemoreceptors do?

detects small changes in the concentration of chemicals

• monitors pH, carbon dioxide, and oxygen levels

what does the somatic sensory pathway do?

carries sensory information from the skin and musculature of the body wall, head, neck, and limbs to the thalamus, which then gets sorted to the region of the body in the primary sensory cortex

what are the somatic motor pathway do?

• the somatic nervous system

• the autonomic nervous system

what does the primary motor cortex do?

activity in a specific portion of the primary motor cortex results in the contraction of specific peripheral muscles

how is the cerebellum involved in the somatic motor pathways?

is responsible for coordination and feedback control over muscle contractions

how does the cerebellum act in somatic motor pathways?

monitions proprioceptive  position) sensations, visual information from the eyes, vestibular (balance) sensations from the inner ear, or movements are underway

what is amyotrophic lateral sclerosis (ALS)?

affects motor neurons in the spinal cord, brain stem, and cerebral hemispheres

• results in atrophy because of the destruction of motor neurons and muscle weakness progresses to paralysis

what is anencephaly?

when the brain fails to develop above the midbrain or lower diencephalon

• cranium may or may not develop, and if it does, it is empty, and light will be able to shine through

what is microcephaly?

a birth defect where a baby’s head is smaller than expected when compared to babies of the same sex and age; babies with microcephaly often have smaller brains that might not have developed properly