Chapter 15 Flashcards
What do motor fibers do?
Send signals to our muscle fibers telling them to contract
What do sensory fibers do?
Either skin of muscle and come in different sizes.
Largest: Info about touch, muscle sensitivity or sense of movement.
Smallest: Info about muscle fatigue, temperature and certain forms of pain
Explain the three parts of the sensory system:
- cutaneous senses
- Proprioception
- Kinesthesis
- cutaneous senses:
-Perception of touch and pain from stimulation of the skin - Proprioception:
-Ability to sense position of body and limbs - Kinesthesis:
-Ability to sense movements of body and limbs
What is the heaviest organ in the body?
The skin
What does the skin do?
protects the organism by keeping damage agents from penetrating the body
What is the epidermis?
Outer layer of skin, which is made up of dead skin cells
What is below the epidermis? and what does it do?
The dermis, it contains mechanoreceptors that respond to stimuli such as pressure, stretching and vibration.
What are the two types of mechanoreceptor?
1) Merkel Receptor
2) Meissner Receptor
1) Merkel Receptor:
- Fires continuously while stimulus is present
-Responsible for sensing fine details
2) Meissner Receptor:
-Fires only when a stimulus is first applied and when it is removed
-Responsible for controlling hand-grip
What are the types of mechanoreceptors deep in the skin?
1) Ruffini Cylinder Fires
2) Pacinian Corpuscle
1) Ruffini Cylinder Fires:
-Continuously to stimulation
-Associated with perceiving stretching of the skin
2) Pacinian Corpuscle
-fires only when a stimulus is first applied and when it is removed
-Associated with sensing rapid vibrations and fine texture
How do nerve fibers travel to the spinal cord?
In bundles (peripheral nerves)
Explain the two major pathways in the spinal cord:
- Medial lemniscal pathway
- Spinothalamic pathway
- Medial lemniscal pathway:
-consists of large fibers that carry proprioceptive and touch information - Spinothalamic pathway
-Consists of smaller fibers that carry temperature and pain information
Where do the signals go in the brain?
The thalamus, the somatosensory receiving area (S1) and to the secondary receiving area (s2) in the parietal lobe
What is the homnculus?
Cortical space for parts of the body
How do we measure tactile aquity?
- Two-point threshold
- Grating aquity
- Two-point threshold
-See when you recognize something as distinct parts - Grating aquity
-grooves go in a certain direction
-determine the orentation
What is raised pattern identification?
Using something like braille to see the smallest size that can be identified
Is there a high density of merkel receptors in the fingertips?
Yeas
Most sensitive parts of the body?
Fingers, upper lip, and big toe
Least sensitive parts of the body?
Upper arm, back, thigh
Explain the idea of overlapping merkel receptors:
None overlap on finers = more sensitive
Overlap at less sensitive parts of the body
What is the cortical magnification factor?
Highly sensitive parts have a bigger representation in the brain
What does the Pacinian corpuscle do (PC)?
Respond to high rates of vibration
Circle guy
Without the PC it only responds to continuous pressure
Explain the two cues we use to perceive texture on?
- Spatial cues:
- Temporal Cues:
- Spatial cues: Bumps and grooves
- size, shape and distribution of surface elements - Temporal Cues: Fine textures, perceived as fingers move across the surface
-Rate of vibration as skin moves across the surface
What is the duplex theory of texture perception?
Might be two receptors responsible for Spatial cues and Temporal Cues:
What do we see when we present various textures to a hand?
- different textures caused different reactions
- Different neurons responded differently to the same texture
