unit 3 Flashcards
muscle twitch is ___ cycle of contraction and relaxation in a muscle fiber
one
- action potential arrives at the motor endplate ACH is released from motor neuron
- ACH binds to ligand gated NA+ channels in the motor end plate, generating an action potential along the sarcolemma
- action potential propagates along the sarcolemma down t tubules
- action potential causes voltage gated ca2_ channels in the sarcoplasmic reticulum to open
latent period/ lag
- ca2+ diffuses out of SR into sarcoplasm and binds to troponin
- active sites on the actin myofilament are exposed and the myosin heads bind to them
- cross bridge cycling begins and continues as long as ca2+ is in the sarcoplasm
contraction
- ca2+ is pumped from the sarcoplasm into the SR
- Ca2+ levels in the sarcoplasm declines and cross-bridge cycling comes to stop
relaxation
- length of sarcomere at the start of contraction
- frequency of stimuli
- muscle fatigue, temp, hydration
variables that affect twitch strength
- muscle size + fascicle arrangement
- which motor units are contracting
- total number of motor units contraction (recruitment or multiple motor unit summation)
variables affecting the whole muscle
allows only brief contraction
too short
too little overlap, weak contraction
too long
T/f muscles usually do not exceed length that leads to no tension produced:
- limitations on bone movements
- elastic filaments (titin)
- CNS monitors + adjusts muscle tones
- reflexive contraction
T
frequency of stimuli – if new stimuli arrive before the first is over, increase or decrease in tension?
increase
- become hyperpolarized –> muscle fiber less excitable
- accumulate ADP + inorganic phosphate –> slow cross bridge cycling, inhibits calcium release
short term muscle fibers fatigue
- fuel depletion –> less ATP made
- electrolyte loss through sweating
- central fatigue –> central nervous system produces less output to motor neurons
long term muscle fibers fatigue
animal naturally engage in variety of behaviors
natural variability
spinal cord arises form the ___ and ends at the ___ ____
brainstem; conus medullaris
spinal cord ends before the vertebral column (connection to the ____ punctures)
lumbar
Cervical + lumbosacral enlargements include neurons associations with the ___ (require more neurons with the limbs)
limbs
spinal cord has ____ grooves on anterior and posterior surfaces
- anterior median fissure (deep groove)
- posterior median sulcus (shallow groove)
longitudinal
specific bilateral region of skin supplied by a single pair of spinal nerves
dermatomes
areas where u find daily dendrites, cell bodies, an d unmyelinated axons
gray matter
areas where myelinated axons dominate
white matter
large bundle of nerve fibers
funiculus
- meninges
- CSF on subarachnoid space (shock absorption)
- vertebrae (structural protection)
- adipose (fat) in epidural space
structures protecting cord
** epidural space is where the epidural happens in ADIPOSE TISSUE and affects spinals roots and nerves and is different than lumbar punctures which is in the space of spinal fluid
ON EXAM
- protect damaging contacts with verebrae
- provide physical stability and shock absorption
- blood vessels in layers deliver o2 + nutrients to spinal cord
- continuous with cranial meninges
meninges
areas where you find mainly dendrites, cell bodies, and unmyelinated axons
gray matter
areas where myelinated axons dominate
white matter
large bundle of nerve fibers
funiculus
___ horns are only present in the thoracic and lumbar segments
lateral
___ neurons of the lateral horns are associated with autonomic division, innervate viscera
motor
- meninges, CSF in subarachnoid space, vertebrae, adipose (fat) in epidural space
protecting spinal cord
dense irregular connective tissue
dura mater
arachnoid mem = 5-6 layers squamous to cuboidal cells adhering to dura mater + loose cells, collagenous, + elastic fibers spanning to the subarachnoid space
arachnoid mater
delicate membrane of 1-2 layers simple to cuboidal cells = collagen & elastic fibers
pia mater
limit side to side movement of spinal cord
denticulate ligaments
carry sensory signals from the receptors to the CNS
afferent fibers
carry motor signals form the CNS to effectors
efferent fibers
innervate skin, skeletal muscles, bones, joints
Somatic fibers
innervate blood vessels, glands, and viscera
viceral fibers
innervate widespread organs such as muscles, skin, glands, viscera, and blood vessels
general fibers
innervate more localized organs in the head, including the yees, ears, olfactory, taste receptors, and muscles of chewing, swallowing, and facial expression
special fibers
individual axons are surrounded by endoneurium
loose connective tissue
bundles of axons (fascicles)
nerves
bundles of axons (fascicles) surrounding by ___
perineurium
nerve is protected form overstretching , injury by ____ = dense irregular connective tissue
epinerurium
Somatic motor neurons have their cell bodies in the _____ horns, axons go through ____ roots
anterior; anterior
autonomic motor neurons have their cell bodies in ___ horns, axons go through ___ roots
lateral; anterior
sensory neurons have their cell bodies in ___ root ganglia, axons either synapse within interneuron in the ___ horns or pass into ___ matter (ascending or descending tracts)
posterior; posterior; white
_____ branch reenter reentered the vertebral canal and innervates the meninges, vertebrae, and spinal ligaments
meningeal
smaller ____ ___ serve the back
posterior rami
larger ___ ____ serve hate body wall & limbs (excluding the back)
- form intercostal nerves in thoracic region
- form nerve plexuses in other regions
anterior rank
- complex, interwoven networks of nerve fibers
- formed from blended fibers of anterior rami of adjacent spinal nerves
- allows multiple spinal nerves to supply the structures
- damage to a single location doesn’t completely cut off info transmission
nerve plexuses
innervates muscles of neck and diaphragm
- phrenic nerve : diaphragm
cervical plexus
innervates muscels of pectoral girdle + upper limb
- ulnar, medial + radial nerve
brachial plexus
innervates muscles of pelvic girdle and lower limb
fermoral nerve
lumbar plexus
innervates muscles of pelvic girdle and lower limb
sciatic nerve
sacral plexus
- generally multi-neuronal –> 2-3 neurons that relay info
- most exhibit spatial relationships among fibers that reflect mapping of the body
- most decussate (cross sides) at some pt]
- once = contralateral
- none or twice = ipsialteral - pathways are paired symmetrically on both sides
sensory and motor pathways
cell body in cranial or spinal ganglia
1st order neuron
cell body in CNS – brainstem or posterior gray matter spinal cord is considered an interneuron
2nd order neuron
cell body in CNS – specifically region of brain called thalamus, neurons considered interneurons
3rd order neuron
UMN has its cell body in ___
- can has 1-2 LMNs
brain
- 1 LMN
- cell body is in brainstem or spinal cord
- axon leaves CNS and synapses with effector (skeletal muscle)
somatic nervous system
- 2 MN chain starting at brainstem or spinal cord
- preganglionic neuron with cell body in CNS, axons leaves
- ganglion aka postganglionic neuron with cell body in ganglia
autonomic nervous system
connects brainstem to cerebrum, relay homeostatic function
diencephalon
connects spinal cord to cerebrum, homeostatic functions, location of cranial nerve nuclei
brainstem
perception, thought, memory, emotion, conscious motor control
cerebrum
muscle activity, posture + balance
cerebellum
brain grows more rapidly than the ____ skull -> folds to occupy available space -> cerebrum covers ____ & ____
membranous; diencephalon; midbrain
central cavity enlarges to form ____
ventricles — interconnected cavities that are filled with cerebrospinal fluid
- cranial bones
- cranial meninges
- CSF
- brain barrier system
protection with the brain
___ mater is pressed directly against the skull — No epidural space or adipose as protection
dura
touches brain directly
pia
- cover + protect CNS
- protect blood vessels + enclose venous sinuses
- CSF
- form skull partitions (dural folds) to limit excessive movements of the brain
protection: cranial meninges
dura mater around the Brain has 2 layers: _____ & _____
periosteal + meningeal
where layers in the dura mater separator, there are dural venous sinuses that collectt ___ ___ + ____ & direct it to the veins of the neck
venous blood + csf
CSF is produced in ventricles at ?
choroid plexuses
_____ in the 4th ventricle connects the ventricles to the subarachnoid space
apertures
lateral ventricles are very close together anteriorly, where they are separated only by the ____ ____
septum pellucidum
- supports brain (buoyancy)
- cushioning shock + absorption
- transport nutrias, chemical messengers, + waste
CSF
____ contains many sensory + motor tracts as well as cranial nerve nuclei (cell bodies of neurons in CNS)
medulla
CSF is absorbed into the superior saggital sinus via the _____ granulations –> drains into internal jugular veins
arachnoid
consists largely of conduction tracts, helps medulla maintain breathing and initiate REM sleep
pons
___ ventricle is found posterior to medulla pons
fourth
**ON EXAM **
corpus callosum is what matter and disrupts what when it is disrupted
white matter + right & left hemisphere
- relay somatic sensory info to thalamus
- relay info to cerebellum from brain and spinal cord
medulla
pyramid contain axons of ______, where many decussate
somatic motor neurons
____ ____ connect pons to the cerebellum
cerebellar peduncles
anterior half of ___ is dominated by white matter tracts – including those that carry sensory and motor info
pons
midbrain processing of visual, auditory info, and tactile sensory info
corpora quadrigemina
integrate visual, auditory, and tactile input; initiate reflexive responses to stimuli
superior colliculi
important in relay of auditory info
inferior colliculi
neurons associated with the ____ ____ of the midbrain regulate the basal nuclei (suppress unwanted body movements)
- associated with Parkinsons
substantia nigra
neurons associated with ___ ____ involved in unconscious regulation and coordination of motor areas
red nuceli
- Heart rate
- Blood vessel diameter
(vasomotor) - Respiration (breathing) * Swallowing
- Vomiting
- Hiccupping
- Coughing
- Sneezing
medulla oblongata functions
____ ____ involves all brainstem regions but the area called _____ is located in the midbrain
reticular formation; RAS
- important for keeping the cerebral cortex alert and conscious (inhibited by sleep center)
- can help with filtering sensory information
- modulates activity of cranial nuclei –> helps coordinates rhythmic activities
RAS
cerebellum is posterior to and only directly connected to the _____
brainstem
___ adjust motor output to maintain coordination, balance, and smooth movements
- more recent discoveries indicate roles in spatial perception, timekeeping, planning, etc
cerebellum
- motor areas notify cerebellum of intent to initiate voluntary muscle contraction
- cerebellum simultaneously receives sensory info from body
- cerebellar cortex determines best way to coordinate movements
- cerebellar sends “blueprint” to cerebrum to coordinate movement
cerebellum
- relays and processes sensory info
thalamus
- controls emotions, autonomic functions, and hormone production
hypothalamus
- processes visual and auditory data
- generates reflexive somatic motor responses
- maintains consciousness
midbrain
- relays sensory information to cerebellum and thalamus
- subconscious somatic and visceral motor centers
pons
- relays sensory info to thalamus and other portions of brainstem
- autonomic centers for regulation of visceral function (cardiovascular, respiratory, and digestive system activities)
medulla oblongata
- control autonomic NS
- initiate physical responses to emotions
- regulate body temperature
- regulate food intake (hunger & satiety)
- regulate water balances
- regulate sleep-wake cycles
- control endocrine
hypothalamus
neuron cell bodies
- short nonmyelinated neurons
gray matter
most myelinated axon (with some nonmyelinated axons)
white matter
many of the functional roles of the cerebrum are associated with neurons whose cell bodies are in the _____ cortex
cerebral
___ matter is involved in transmitting info within hemispheres, btw hemispheres, and btw the cerebrum and other parts of the brain
white
btw gyri or lobes in a hemisphere
association tracts
btw cerebral hemisphere
commissural tracts
btw cerebrum and the region of the brain or spinal cord
projection tracts
language, math, logic
left
visual-spatial, intuition, emotion, artistic, musical abilities
right
- taste
somatic sensation
sensory integration
visual processing
spatial perception
language processing
numerical awareness
parietal lobe
visual awareness
visual processing
occipital lobe
hearing, smell, learning, emotion, learning comprehension, memory consolidation, verbal memory, visual + auditory memory
temporal lobe
taste, pain, visceral sensation, consciousness, emotion, empathy, cardiovascular homeostasis
insula
abstract thought, explicit memory, mood, motivation, foresight, planning, decision making, emotional control, social judgment, voluntary motor control, speech production
frontal lobe
disproportionately large areas associated with more ___ control of movements
precise
control of movements is most commonly ____
contralateral
directs voluntary movements
- requires stimulative from other neurons
axons project to brainstem and spinal cord
primary motor cortex
stored patterns, programmed motor skills, planning movements
premotor cortex
perception of general sensory info is most often ____
contralateral
If a person loses their vision following a stroke, but their visual memories are unaffected, what part of the cerebral cortex was damaged?
damage likely occurred in the primary visual cortex (V1), located in the occipital lobe.
