KEY CONCEPTS Flashcards
(26 cards)
Describe the factors needed to estimate the consequences of a spinal cord injury.
The factors include the segment at which the injury occurred, the ascending and descending pathways that are damaged, and where these pathways cross the midline.
Explain the role of cranial nerve VIII in hearing.
Cranial Nerve VIII, also known as the vestibulocochlear nerve, carries afferent fibers from hearing receptors in the cochlear division and equilibrium receptors in the vestibular division from the inner ear to the brain stem.
Define the functions of the tensor tympani and stapedius muscles.
The tensor tympani and stapedius muscles contract reflexively in response to loud sounds to protect hearing receptors from damage, with motor input from the trigeminal nerve (V) and facial nerve (VII).
How do the tensor tympani and stapedius muscles contribute to hearing protection?
They contract reflexively to reduce the movement of the ossicles in the middle ear, thereby preventing excessive sound pressure from reaching the inner ear.
Identify the cranial nerves involved in the reflexive contraction of the tensor tympani and stapedius muscles.
The trigeminal nerve (CN V) innervates the tensor tympani, while the facial nerve (CN VII) innervates the stapedius.
Discuss the changes in hearing ability as one ages, particularly regarding high pitch sounds.
As people age, they tend to hear less high pitch sounds due to the degeneration of hair cells in the cochlea, which are more sensitive to higher frequencies.
What is the primary function of the outer hair cells in hearing?
Outer hair cells play a crucial role in amplifying sound vibrations and enhancing sensitivity to sound, particularly in the higher frequency range.
Explain the significance of the midline crossing of ascending and descending pathways in spinal cord injuries.
The midline crossing of these pathways is significant because it affects the side of the body that is impacted by the injury, influencing motor and sensory functions.
Describe the process of inner hair cell excitation in the auditory system.
Movement of the basilar membrane deflects the hairs of inner hair cells, with stereocilia projecting into K+-rich endolymph, where the longest hairs are enmeshed in the gel-like tectorial membrane.
Explain the characteristics of nonencapsulated nerve endings.
Nonencapsulated (free) nerve endings are abundant in epithelia and connective tissues, mostly nonmyelinated, small-diameter group C fibers, and respond primarily to temperature, pain, or light touch.
Define visceral pain and its characteristics.
Visceral pain results from stimulation of visceral organ receptors and is felt as vague aching, gnawing, or burning, activated by tissue stretching, ischemia, chemicals, or muscle spasms.
How does referred pain occur?
Referred pain occurs when pain from one body region is perceived as coming from a different region because visceral and somatic pain fibers travel along the same nerves, leading the brain to assume the stimulus comes from a common somatic region.
Provide an example of referred pain.
An example of referred pain is experiencing left arm pain during a heart attack, where the brain misinterprets the source of the pain.
Explain how the brain controls heart rate through autonomic innervation.
The brain controls heart rate through autonomic innervation via cranial nerves, specifically the IX. Glossopharyngeal Nerves, which have fibers running from the medulla to the throat, innervating parts of the tongue and pharynx for swallowing.
What sensory functions are associated with the glossopharyngeal nerves?
The sensory functions of the glossopharyngeal nerves include conducting taste and general sensory impulses from the pharynx and posterior tongue, as well as impulses from carotid chemoreceptors (monitoring O2 and CO2 levels) and baroreceptors (monitoring blood pressure).
Describe the role of the Vagus Nerve in the parasympathetic nervous system.
The Vagus Nerve is a cranial nerve that extends beyond the head and neck region, providing parasympathetic motor fibers to the parotid salivary glands and regulating activities of the heart, lungs, and abdominal viscera.
Define micturition and its significance in the nervous system.
Micturition is the process of urination, which involves reflex arcs that begin with sensory input and are crucial for controlling bladder function.
Explain the origin of the fibers that innervate the muscles of the pharynx and larynx.
The fibers that innervate the muscles of the pharynx and larynx originate from the medulla.
How do visceral reflex arcs function in the body?
Visceral reflex arcs function by receiving information from visceral sensory neurons, allowing the body to respond to internal stimuli.
Do sensory fibers play a role in the autonomic nervous system?
Yes, sensory fibers carry impulses from thoracic and abdominal viscera, baroreceptors, chemoreceptors, and taste buds, contributing to the autonomic nervous system’s regulation.
Explain the significance of cranial nerves in the autonomic nervous system.
Cranial nerves, particularly the Vagus Nerve, play a significant role in the autonomic nervous system by controlling various involuntary functions beyond the head and neck.
Describe the relationship between sensory input and reflex arcs in the context of urination.
All reflex arcs related to urination begin with sensory input, which is essential for initiating the micturition reflex.
