APP Exam 2 Flashcards
What is the biosynthesis for Acetylcholine?
Acetyl-CoA and Choline
What is synthesized to create Serotonin?
Tryptophan—>5-Hydroxytryptophan—–>5-Hydroxytrptamine
For Catecholamines, what is used to create norepinephrine and epinephrine?
Tryosin—–>DOPA (Dihydroxy-phenylalamine——->Dopamine—->Norepinephrine—–>Epinephrine
What are Ligand-gated channels (ionotropic receptors)?
a membrane channel that which is opened when a ligand binds to the receptor. The channel activation is brief
What are Metabotropic receptors?
G-protein coupled receptors. The binding of the ligan initates the production of a second messanger that modulates the ion channels.
What is the difference between ionotropic receptors and metabotropic receptors?
ligand-gated channels: membrane channel that has a ligand present
metabotropic receptors: more complex, has g-coupled receptors
Describe the Glutamate neurotransmitter and the receptors asscociated with it
-is the main excitatory neurotransmitter in the CNS
-has AMPA receptor, NMDA receptor, and Kainate receptor
Describe how NMDA receptors are unique
involved with Glycerine binding, blocked by magensium=removed by depolarization from adjacent AMPA and kainate receptors. The Excitatory Post Synaptic Potential created by these receptors (they work together)
Describe the GABA neurotransmitter and the receptors that are involved.
-major inhibitory mediator in the brain and mediates presynaptic and postsynaptic inhibition
-has three subtypes of receptors (A, B, and C) with A and B being more common in CNS.
-A and C receptors are ionotropic and allow entry of chloride ions into cell-IPSP
-C type found in retina
-B receptors are metabotropic and allow exit of K+, inhibit adenylyl cyclase and allow calcium to come into cell
-A receptors are also made up of 5 subunits
The ________ neurotransmitter is utilized at neuromuscular junction, in autonomic ganglia, in postganglionic parasympathetic nerve-target organ junctions, and some postganglionic sympathetic nerve-target junctions.
Acetylcholine
What structure is Acetylcholine synthesized in?
the nerve terminal, Choline is brought into the cell via a Na+ dependant choline transporter, Choline acetyltransferase is the enzyme for synthesis
Describe the receptors associated with Acetylcholine?
Nicotinic cholinergic receptors: nicotine is agonist, ionotropic receptor, found at neuromuscular junction, found in CNS and autonomic ganglia
Muscarinic cholinergic receptors: metabotropic
Describe the subtype 2 and subtype 3 for Muscarinic Cholinergic receptors
M2=located in the heart and is inhibitory
M3=located on glands and smooth muscle and is excitatory
Which chemical transmitter is present at most sympathetic postganglionic endings?
norepinephrine
Where is norepinephrine and epinephrine synthesized by
the adrenal medulla=blood stream. Most output is epinephrine
What has a greater affinity for norepinephrine?
alpha-1 adrenoreceptors
what has a greater affinity for the Beta receptors?
Epinephrine
What are the functions of the alpha-1 receptors
vasoconstriction
what is the function of B1 receptors?
increased heart rate, vasodilation
what is the function of the Beta 2 receptors?
bronchodilation, lungs; GI, skeletal muscle
Where is the highest concentration of Serotonin present at?
in blood platelets and GI tract. Also is present in brain stem in the midline raphe. This then projects into the hypothalamus, limbic system, neocortex, cerebellum, and spinal cord. Also plays a major role in mood disorders
Define Mechanoreceptors
touch and pressure
Define proprioceptors
info about muscle length and tension (position sense)
Define Thermoreceptors
heat and cold
Define Nociceptors
pain, extreme heat or cold
Define Chemoreceptors
changes in chemical compositions (which include receptors for taste and smell)
Define Photoreceptors
respond to light
What is a dermotome
the area of skin that maps to a specific spinal cord level
Describe the mechanisim associated with a dermatome map
the numbering refers to the spinal cord level that innervates that portion of the skin
What is referred pain?
felt in a somatic structure that is different than the true site of the pain. ex: something is wrong with the heart but you feel it in your shoulder instead
Describe the Doral Column Pathway
function: descriminative touch and position sense
-conscious proprioception-position of body parts
-can discriminate touch
-fine form and texture
-stereognosis: feel something with the hand but you can’t see it with your eyes
-vibration sense
-goes through the entire length of the spine
-afferent pathway- towards the brain
Describe the Spinothalamic Tract
-function: pain and temperature
-from spine to thalamus
-pain sensation
-temperature sensation
-touching something and you can tell what it is
-the pain pathway
-coarse touch
Describe the Spinocerebellar pathways
-carry sensory and proprioception information
-carry unconscious proprioception from the body to cerebellum
-tells the postions of the upper and lower extremities
-from the spine to cerebellum
What are motor pathways?
-control of the muscles by descending pathways
-takes two neurons to get info from cortex to the muscles
-first neuron: upper motor neuron and found in CNS
-second neuron: lower motor neuron and it travels to the muscle in the periphery
What is the Cortiocospinal system (pyramidal system)?
-very clinically important for most muscles
-controls fine movements of the distal musculature
-originates in the frontal lobe of the cortex (precentral gyrus)
-takes two nurons to get the info from the cortex to its motor unit (upper motor neuron and lower motor neuron)
-upper motor neuron will be long and myelinated and go from cortex and stay in CNS and the lower motor neuron (alpha motor neuron); travel to muscle in periphery
What can happen if the corticospinal system is damaged?
paralysis
what is the main function of the extrapyramidal system?
postural control, originates in the brain stem, support role
What is the organization of the CNS?
-Cortex
-diencephalon (deeper conception)-thalamus and hypothalamus
-brain stem-medulla, pons, midbrain
-cerebellum
-spinal cord-cervical, thoracic, lumbar/sacral
What is the stretch reflex?
when a skeletal muscle with an intact nerve supply is stretched=contracts. Also known as the monosynaptic reflex
What is deep and visceral pain?
-there are only C fibers for deep pain (sharp pain)
-poorly localized, can be nauseating, accompanied by sweating and change in blood pressure.
-ex: muscle spasms associated with injuries
Describe the mechanisim of deep pain and how it is carried in the CNS?
afferent fibers from visceral structures reach the CNS via the sympathetic and parasympathetic nerves (ANS), visceral pain can be very severe and the receptors in the walls of hollow organs can be sensitive to distention. When inflamed, relatively minor stimuli can cause severe pain
What is the mechanisim for the stretch reflex?
-stretch muscle—–>activation of muscle spindle—–> legs kick
describe the meissner’s corpuscle
dendrites that are encapsulated in connective tissue and is involved in light touch, changes in texture, or slow vibrations
Describe Merkel’s cells
they are expanded dendritic endings and are used for sustained pressure and touch
Describe the hair follicle receptors
dendrites wrapped around the hair follicle and is sensitive to displacement of the hair
what are the superficial receptors?
meissner’s corpuscle, merkel’s cells, and hair follicle receptors
what are the fine touch for deeper structure receptors?
pacinian corpuscle
what is the pacinian corpuscle?
unmyelinated dendritic endings that are encapsulated by concentric lamellae of connective tissue and is used for deep pressure and fast vibrations
what are ruffini endings?
enlarged dendritic endings with elongated capsule and is used for sustained pressure
______ is mediated by free nerve endings throughout the skin and provide information perceived as crudely localized touch or pressure. They can also carry the sensations of tickle and itching. Carried by the A-alpha and C fibers
course touch (non-discriminative touch)
How can pain sensations be modulated through the gate-controlled mechanisim?
-takes 3 neurons to get one piece of information to the cortex
-first order neuron (with receptor), second order neuron, and third order neuron (ends in the cortex)
-rubbing or shaking an injured area and help with pain
-can involve interneurons in dorsal horn that release endogenous opioids such as enkephalin and dynorphin
what is the role of enkephalin or other opiates?
decreases Ca+ influx=decreases the duration of the action potential. at the synapse, the increase of K+ going out decreases EPSP`
______ is a part of a descending pathway that modulates pain sensations by inhibition of the primary afferent pathway in the dorsal horn and sends fibers to raphe nucleus (seretonin) and to catecholaminergic neurons in brain stem
periaqueductal gray (PAG)
What is nystagmus?
a tremor- like movement of the eyes, with the eyes moving in one direction slowly, then rapidly moving back in the opposite direction. occurs from damage to the vestibular system or to the cerebellum
what is the difference between conductive deafness and sensorineural deafness?
conductive deafness: occurs when transmission of vibrations are prevented in the outer or middle ear (ex: swimmer’s ear)
sensorineural deafness: occurs from damage to the receptors of the cochlear nerve (less common)
Describe the structures of the middle ear
three small bones
-the hammer (malleus)
-anvil (incus)
-stirrup (stapes) MIS
the middle ear is separated from the external ear by the eardrum and connected to the back of your nose and throat by the eustachian tube
Describe the structures associated with the inner ear
bony labyrinth that is filled with perilymph (low K+ levels)
-membraneous labyrinth that is filled with endolymph (K+ rich)
3 components:
-cochlea (for hearing)
-semicircular canals (measures head rotations)
-otolith organs (responds to gravity and head tilts=utricle and saccule)
What structure detects movement of the head
semicircular canals-detects acceleration and deceleration (rotational acceleration), three semicircular canals in ear ear and is filled with endolymph, slushing of the bucket example. utricle (horizontal) and sacule (verticals acceleration)
Determine how physiological nystagmus can be produced
rotational test: spinning the person and observe nystagmus. tilting the head can test the different semicircular canals
caloric test: put warm water and tilt head to put one of the canals in a vertical position. you can only test one side at a time
What are pathological nystagmus examples?
vertigo, dizziness, lightheadedness, and motion sickness. damage to semicircular canals or cerebellum
What systems helps decipher spatial orientation?
- visual system
- vestibular system (equilibrium and balence)
- conscious proprioception and cutaneous exteroreceptors (dorsal column system)
2 can work but 3 would be most favorable
what is the function of the utrcle
detection of head position and detection of horizontal acceleration (and deceleration)`
List the mechanism for sensory inputs that provide information synthesized in the brain stem for the sense of position in space and for controlling eye movement
-vestibular nerve from inner ear that connects with the vestibular nuclei of the brain stem and with the cerebellum
-vestibular nuclei processes the raw data about head movement
-helps control movement of the muscles of the neck and the postural muscles of the body
-sends info up into brain stem to help control eye and head movement
How is a sound wave turned into an action potential?
- sound waves pass through the air filled ear outer ear canal
- sound vibrates the ear drum and the vibration is conveyed across the air-filled middle ear by the ossicles. The ossicles pass vibrations to the oval window, a membrane that seals the opening to the cochlea
- the vibrations reach the fluid filled inner ear where, inside a snail shell shaped cochlea, neurons are activated. the hair cells vibrate and cause depolarization which results in an action potential (influx of calcium)
How is that we can locate where a sound comes from?
the direction from which a sound comes is determined by comparing the loudness of the sound to the two ears, but also by comparing the timing of the sound reaching the two ears, the nuclei in the brain stem helps compare the timing of the sounds
Describe the auditory pathway
passes from the eighth cranial nerve afferent fibers to the dorsal and ventral cochlear nuclei to the inferior colliculi to the thalamic medial geniculate body and then to the auditory cortex.
What pathways are using the information that is detects head and eye movement?
central vestibular pathway
What is the role of the vestibular nuclei for the process of focusing eye on the target
primarily concerned with maintaining the position of the head in space.
Describe the three main layers of the retina
- rods and cones
- inner nuclear layer (interneurons)
- ganglion cell layer (which form the optic nerves)
pupillary light reflex is…
shining a light into one eye causes the pupils in both eyes to constrict and limit the light going into the eyes, used to help test the integrity of the brain stem
Detail the pupillary light reflex mechanism
input from optic nerve goes to the pretectal area of the brainstem, input then goes to the Edinger-Westphal nuclei of the 3rd cranial nerve, causes constriction of the muscles in the pupil