Week 9 - Chapter 16 Somatic Sensation
________ is the conscious or subconscious awareness of changes in the external or internal environment.
Sensation
________ is the conscious awareness and interpretation of sensations, primarily a function of the cerebral cortex.
Perception
How does the type of sensation and the reaction vary?
Varies depending on where sensory impulses are sent in the CNS.
A ________ is a type of sensation, and usually, each sensory neuron serves only one modality
Sensory modality
General senses include:
Somatic (touch, pressure, vibration, warmth, cold, pain, itch, tickle, proprioception) and visceral senses
Special senses include:
Smell, taste, vision, hearing, and equilibrium
What four events must occur for a sensation to arise?
Stimulation, transduction, generation of impulses, and integration
______ receptors are associated with general senses (like free nerve endings)
Simple
_______ receptors are associated with special senses (like the eyes and ears)
Complex
How do sensory receptors respond to stimuli?
By producing receptor potentials
What is adaptation in sensory receptors?
Adaptation is the decrease in sensitivity during a long-lasting stimulus. Receptors can be rapidly or slowly adapting.
Somatic sensations include:
Tactile sensations (touch, pressure, vibration, itch, tickle), thermal sensations (warmth, cold), pain, and proprioception
Where are receptors for tactile, thermal, and pain sensations located?
In the skin, subcutaneous tissue, and mucous membranes of the mouth, vagina, and anus
What types of receptors detect touch?
Tactile corpuscles of touch (rapidly adapting) and hair root plexuses, and slowly adapting nonencapsulated sensory corpuscles
What types of receptors detect pressure?
Nonencapsulated sensory corpuscles and lamellar corpuscles
What types of receptors detect vibration?
Tactile corpuscles and lamellar corpuscles
What types of receptors detect itch, tickle, and temperature?
Free nerve endings (itch, tickle, thermoreceptors)
Where are cold and warm receptors located?
Cold receptors are in the stratum basale of the epidermis; warm receptors are in the dermis
_______ receptors (free nerve endings) are found in nearly every body tissue.
Pain
Fast pain is carried by ____ fibers (medium diameter, myelinated)
A
Slow pain is carried by ___ fibers (small diameter, unmyelinated).
C
Where are proprioceptors located?
In muscles, tendons, joints, and the inner ear
What are the types of neurons involved in somatic sensory pathways?
First-order, second-order, and third-order neurons
Where do somatic sensory neurons send signals besides the cerebral cortex?
The cerebellum and reticular formation of the brainstem.
What pathway carries touch, pressure, vibration, and proprioception signals?
The posterior column–medial lemniscus pathway
What pathway carries pain, temperature, touch, and pressure signals?
The anterolateral pathway
Sensations from the face, nasal cavity, and oral cavity are transmitted through the _______
Through the trigeminothalamic pathway
Where do somatic sensory inputs from different body parts go in the brain?
They are received by specific regions of the primary somatosensory cortex (postcentral gyrus) in the cerebrum
What pathways transmit nerve impulses to the cerebellum for posture and coordination?
The anterior and posterior spinocerebellar tracts
Lower motor neurons are:
Motor neurons that control movement and are the final common pathway for movement control
What four neural circuits provide input to lower motor neurons?
Local circuit neurons, upper motor neurons, basal nuclei neurons, and cerebellar neurons
What is the primary motor cortex?
The precentral gyrus of the brain, which is the major control region for voluntary movements
What pathways do upper motor neurons use to send signals to lower motor neurons?
Direct pathways (corticospinal and corticobulbar pathways) and indirect pathways (rubrospinal, tectospinal, vestibulospinal, reticulospinal tracts)
What is the role of the corticospinal pathways?
They convey nerve impulses from the motor cortex to skeletal muscles in the limbs and trunk
What do the corticobulbar pathways control?
Skeletal muscles in the head
What does the cerebellum do in movement control?
It helps with learning and performing rapid, coordinated, highly skilled movements, and maintaining balance and posture
What two systems control sleep and wakefulness?
The suprachiasmatic nucleus and the reticular activating system
How many stages are there in non-rapid eye movement sleep?
Four stages
What is a coma?
A state of unconsciousness where an individual has little or no response to stimuli
What is memory?
The process of storing and retrieving information learned