exam 2 Flashcards
what do tendons connect?
connect muscles to bone
what are skeletal muscles made up of?
striate muscle (overlapping layers of myosin and actin)
muscle fiber:
1) fast twitch fibers- contract quickly and fatigue easily
2) slow-twitch fibers- contract slowly and with less intensity, but fatigue more slowly
muscle synergistis vs antagonists
syn: work together to execute motion
ant: work in opposite to one another
where can motor neurons be found?
1) cell bodies in CNS
2) efferent axons in PNS
3) axon terminals on muscle fibers
neuromuscular junction
- synapse that motor neurons form on muscle fibers
- terminals of motor neurons release actetylcholine and binds to muscle receptors
what makes up a motor unit?
- motor neurons and all of the fibers it contacts
- 1 motor neuron: many muscle fibers
pyramidal motor system
- contacts motor neurons directly
- pathway involving cell bodies in M1 and axons that form syapses on motor neurons in spinal cord
M1
- primary motor cortex
- on precentral gyrus of frontal lobe
- has topography motor of map of the body
- motor planning for voluntary motion
- activity of neurons here associated with direction of a movement (certain neurons like certain sides. when a limb moves in the direction that particular neuron likes, it will fire more A.P. and the other side is inactivated)
complex movement requires ____ to contract multiple ____ to __
primary motor cortex
muscle synergists
different degrees
non-primary motor cortex
1) supplementary motor area- generates motor programs for preplanned movement
2) premotor cortex- generates motor programs in reaction to external events
Extrapyramidal Motor System
modulates pyramidal system and is involved in:
1.) initiation and cessation of motion
2.) precision of motor control
includes basal ganglia and cerebellum
how do basal ganglia and cerebellum influence motor cortices?
via parallel pathways through nuclei of
VA + VL complex of thalamus
basal ganglia
receives dopamine input from midbrain
has D1 and D2pathways for voluntary motions
D1like: “go”, dopamine increases
D2 like: “stop”, inhibited under domapine
increase in dopamine= increase in movement
cerebellum in extrapyramidal motor system
contributes to precision of motor control
what occurs in Parkinson’s
less D1 signals in basal ganglia
more D2 signals
cerebellar agenesis
cerebellum never forms
(walk and speech require precision control)
what is sensory transduction?
convert stimulus into stream of action potential
what do receptor cells do?
detect specific energies and chemicals in environment
if 2 species both posses a given sense, will they receive the same stimuli?
no, energy can be tuned differently
different types of receptor cells to distinguish inputs that are qualitavely and quantitvely different (different kind and amount)
ex: elephants and cats can hear sounds humans cant
receptive fields
where receptor cell detects stimulus
ex: frequency range in auditory system
sensory adaptation
- a progressive decrease in a receptor’s response to a sustained stimulus
- (if change doesn’t have a consequence, body will ignore it)
1) phasic receptors- display adaptation
2) tonic receptors- responds if stimulus is there (remind brain stimulus is still present, even if it’s not worth much attention)
sensory cortex
- each system has a primary sensory cortex that receives sensory info from thalamus
- sensory info detected by receptor cells
- perception occurs in the brain
somatosensory cortex
- processes touch info and has map of skin surface
- located in central gyrus on parietal lobe
- somatotopic map: receptive fields in neighboring areas of sin are processed by neighboring area in brain
non-primary/ association cortices
receive info from primary sensory cortex and integrate inputs from multiple senses
* can be polymodal neurons (respond to multiple different forms of sensory info)
primary somatosensory cortex
- where conscious perception of touch beings
- detects energy or chemical
- on post-central gyrus in parietal lobe
- has topographical map of skin surface
proprioception
perception of the position of the limbs and body in space (ex: detect stretch in tendons, contraction of muslces)
pacinian corpuscles
- receptor cell for sensing pressure and texture
- phasic
dorsal root ganglia (DRG) neurons
nerve endings in skin –(spinal cord)–> axon terminals in CNS
action potential activated by pressure in nerve endings on skin
dermatome
- strip of skin that collects info for the 31 spinal nerves
- organized from superior to inferior
papillae
- bumps on surface of the tongue with taste buds and other sensory receptors
- increase SA = increase # of sensory receptors
- filiform papillae: no taste buds; only somatosensory receptors
taste buds
- receptor cells for taste
- have microvilli: connect taste buds to surface of the tongue
- release ATP around env. and then nerve ending picks it up. Not as targetted
sour taste
- acidic (large H proton concentration)
- taste receptors have hydrogen channels
salt taste
NaCl dissolves into Na+ and Cl- in saliva
receptor cells have Na+ channels
T1R vs T2R receptors
T1R: for sweet taste
T2R: for bitter taste
umami taste
- bitter taste
- caused by glutamate
what is different about gustatory pathway from other sensory pathways?
ipsilateral- never crosses midline
olfactory receptor cells
- located in olfactory epithelium
- will do the action potential themselves. Not communicate with other cell that does
what is different about the olfactory sense from other senses?
pathway does not stop at thalamus
(info goes from olfactory bulb to cortex)
glomeruli
synapse where receptor and mitral cells connect
olfactory bulb
where olfactory info gets processed
what does the vomeronasal organ do?
detects pheromones (to communicate within species)
