164 terms

Test 3: Muscle, Nervous, and Spinal Cord

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functions of spinal cord
integrates and processes information on its own, in addition to relaying information to and from the brain
central nervous system
spinal cord and brain
cervical enlargements
expanded regions with increased gray matter to provide innervation of the pectoral girdle and upper limbs
lumbar enlargements
expanded region of the spinal cord with increased gray matter to provide innervation of the pelvic girdle and lower limbs
conus medullaris
where the spinal cord tapers to a conical tip, which is at or inferior to the level of the first lumbar vertebrae (L1)
filum terminale
a strand of fibrous tissue, originating at the conus medullaris and extending through the vertebral canal to the second sacral vertebra, ultimately becoming part of the coccygeal ligament
dorsal root ganglia
contains sensory neuron cell bodies, each segment of the spinal cord is associated with a pair of these
dorsal root
contains the axons of the sensory neurons in the dorsal root ganglion; each segment of the spinal cord is associated with a pair of these
ventral root
contains axons of somatic motor neurons and sometimes visceral motor neurons that control peripheral effectors; each segment of the spinal cord is associated with a pair of these
spinal nerve
location where sensory and motor fibers unite, emerging from intervertebral foramina; distal to each dorsal root ganglion. is considered a mixed nerve
mixed nerve
contains both sensory and motor fibers
sciatic nerve
largest nerve in the body
cauda equina
inferior extension of the ventral and dorsal roots and the filum terminale in the vertebral canal
spinal meninges
a series of specialized membranes that provide physical stability and shock absorption for neural tissues of the spinal cord
meningeal layers
dura mater, arachnoid mater, pia mater
dural mater
tough, fibrous outermost layer of the spinal cord; caudally it forms the coccygeal ligament with the filum terminale
coccygeal ligament
formed where the spinal dura mater tapers from a sheath to a dense cord of collagen fibers that ultimately blend with components of filum terminale
epidural space
separates the dura mater from the inner walls of the vertebral canal
subdural space
internal to the inner surface of the dura mater; separates the dura from the arachnoid mater
arachnoid mater
middle meningeal layer
subarachnoid space
internal to the arachnoid mater; contains cerebrospinal fluid
cerebrospinal fluid
acts as a shock absorber and used for spinal tap
pia mater
innermost meningeal layer; bound firmly to the underlying neural tissue
denticulate ligaments
• Lateral extensions of pia mater that pass through the arachnoid layer and attach to the internal surface of the dura mater • Function to anchor the spinal cord
central gray matter
surrounds the central canal in the spinal cord and contains cell bodies of neurons and glial cells
horns
projections of gray matter toward the outer surface of the spinal cord
central canal
located on the spinal cord on the horizontal bar of the H
white matter
peripherally situated; contains large numbers of myelinated and unmyelinated axons organized into tracts and columns
nuclei
groups of neuron cell bodies in spinal cord gray matter
posterior gray horns
contain somatic and visceral sensory nuclei
anterior gray horns
contain neurons concerned with somatic motor neurons
lateral gray horns
contain visceral motor nuerons
gray commissures
posterior and anterior to the lateral canal; contain axons of interneurons that cross from one side of the cord to the other
white matter
divided into six columns (funiculi), each containing tracts (fasciculi)
vertebra sections
cervical, thoracic, lumbar, sacral
epineurium
outermost layer of connective tissue on the spinal nerve; a dense network of collagen fibers
perineurium
middle layer of connective tissue on the spinal nerve; partions the nerve into a series of bundles (fascicles) and conveys blood vessels into each individual fiber
endoneurium
inner layer of connective tissue on the spinal nerve; composed of delicate connective tissue fibers that surround individual axons
white ramus
first branch of spinal nerve in the thoracic and upper lumber region; contains myelinated axons going to an autonomic ganglion
gray ramus
exits the autonomic ganglion, carries axons that innervate glands and smooth muscles in the body wall or limbs back to the spinal nerve
autonomic nerve
nerve that carries fibers to internal organs
rami communicantes
white and gray rami, collectively
dorsal ramus
provides sensory/motor innervation to the skin and muscles of the back
ventral ramus
supplies ventrolateral body surface, body wall structures and limbs
nerve plexus
complex, interwoven network of nerves
four major nerve plexuses
cervical, brachial, lumbar and sacral plexuses
cervical plexus
consists of the ventral rami of C1-C4 and some fibers from C5; innervates the muscles of the neck, thoracic cavity and diaphragm
brachial plexus
consists of ventral rami C5-T1; innervates the pectoral girdle and upper limbs; nerves in this plexus originate from cords or trunks
lumbar plexus
contains fibers from spinal segments T12-L4; originates from the posterior abdominal wall and ventral rami of nerves supplying the pelvic girdle and lower limbs
sacral plexus
contains fibers from spinal segments L4-S4; originates from the posterior abdominal wall and ventral rami of nerves supplying the pelvic girdle and lower limbs
neural reflex
rapid, autonomic, involuntary motor response to stimuli
reflex
helps preserve homeostasis by rapidly adjusting the functions of organs or organ sytems
receptor
specialized cell that monitors conditions in the body or external environment; has a characteristic range of sensitivity
innate refelx
genetically determined reflex
acquired reflex
reflex that is learned following repeated exposure to a stimulus
spinal reflex
reflex in which important interconnections and processing occur inside the spinal cord; range from monosynaptic to polysynaptic
somatic reflex
reflex which controls skeletal muscle contractions
visceral (autonomic) reflex
controls the activities of smooth and cardiac muscles and glands
quadriplegia
loss of sensation and motor control of the upper and lower limbs
myosin
thick filaments of a muscle
actin
thin filaments of a muscle
sarcoplasmic reticulum
releases calcium
Z line
boundary of a sarcomere, point of anchor for thin actin filaments
H zone
The region at the center of an A band of a sarcomere that is made up of myosin only and gets shorter during muscle contraction.
I band
contains only thin filaments
fascicle
bundle of muscle fibers
perimysium
connective tissue covering surrounding each muscular fascicle
endomysium
connective tissue that enclose a single muscle cell
tendon
attaches muscle to bone
sarcomere
contractile unit of muscle
sarcolemma
plasma membrane of a muscle fiber
myofibril
long organelle found within muscle cell
Epimysium
connective tissue that covers the entire muscle
A band
where myosin is; dark band
Axon terminal
The endpoint of a neuron where neurotransmitters are stored.
neurotransmitter
chemical used by a neuron to transmit an impulse across a synapse to another cell
T Tubule
narrow tubes that are continuous with the sarcolemma and extend into the sarcoplasm
motor end plate
The portion of the cell membrane at the neuromusclar junction; essentially the postsynaptic membrane at the synapse.
synaptic cleft
synaptic gap or synaptic space; tiny gap between the terminal of one neuron and the dendrites of another neuron (almost never touch); location of the transfer of an impulse from one neuron to the next
synaptic vesicles
release neurotransmitters which then bind with a dendrite receptor site
acetylcholin
vesicles dump this so that the axon terminal has a way to communicate with the motor end plate.
action potential
causes a voltage charge which occurs in the plasma membrane of the neuron
motor neuron
this carries information from the brain to the muscles; also called "efferent"
acetylcholinesterase
An enzyme that breaks down the neurotransmitter acetylcholine.
terminal cisternae
enlarged areas of the sarcoplasmic reticulum surrounding the transverse tubules, which store calcium for release at the start of muscle contraction
neuromuscular junction
the junction between a nerve fiber and the muscle it supplies
aponeurosis
a sheet of fibrous tissue binding muscles together or muscle to bone
sodium potassium pump
A special transport protein in the plasma membrane of animal cells that transports sodium out of the cell and potassium into the cell against their concentration gradients.
calcium pump
Active transport protein; pumps calcium ions across a cell membrane against their concentration gradient.
tropomyosin
A helical protein that winds around actin helices in skeletal and cardiac muscle cells to form the thin filament of the sarcomere.
troponin
a smaller calcium-binding protein attached to the tropomyosin
cross bridge
The connection of a myosin head group to an actin filament during muscle contraction (the sliding filament theory).
power stroke
The step in the sliding filament theory during which myosin undergoes a conformational change to its low energy state, in the process dragging the thin filaments (and the attached Z lines) toward the center fo the sarcomere.
release/reactivate energy in myosin and active transport for calcium into terminal cisternae
ATP is used to what during muscle contractions?
latent period, contraction phase, and relaxation phase
3 phases of a muscle twitch
latent period
begins at stimulation and typically lasts 2msec and continues until calcium is released from the terminal cisternae
contraction phase
begins as Calcium bind to troponin and myosin "cross bridge" bind to actin and power strokes are occurring; lasts about 15msec
relaxation phase
Calcium is being actively transported back into the terminal cisternae causing calcium levels to fall, active sites on Actin are being re-covered by tropomyosin, and tension falls to resting levels: lasts about 25msec
treppe
repeated stimulation after relaxation phase has completed in a muscle. Can occur over the next 30-50 stimulations.
motor unit
a motor neuron and all the muscle cells it stimulates
multiple motor unit summation
The strength of a muscle contration is determinded not only by the frequency of stimulation, but also by the number and size of motor units recruited, The number of motor units that are recruited is determined by the number of motor neurons that are stimulated by the central nervous system
wave summation
increased tension resulting from increasing frequency of stimulation
Incomplete Tetanus
______is repeated stimulation of the muscle so that the muscle is never allowed to completely relax. will yield increased tension is produced
Complete Tetanus
if stimulation frequency is high enough, muscles never BEGIN to relax and is continuous contraction
isotonic or isometric
Contractions can be classified as...
isotonic contraction
involving muscular contraction in which tension increases and the muscle length changes
concentric or eccentric
isotonic contractions can be either...
concentric
contraction in which the tension exceeds the load and the muscle shortens
eccentric contraction
contraction in which tension is less than the load and the muscle lengthens
isometric contraction
tension never exceeds the load and the muscle length never changes
creatine
A substance, stored in the muscles, that helps supply energy for muscle contraction and can be taken as a supplement or created by your own body. this is a way to store ATP in the muscle.
fast fibers
white fibers; large in diameter, contain densely packed myofibrils and large glycogen reserves and relatively few mitochondria
slow fibers
red fibers; half the diameter of fast fibers and take about 3x as long to contract after stimulation; surrounded by extensive capillaries; therefore higher supply of oxygen; contain myoglobin (reserve of oxygen)
fast, slow, and intermediate fibers
Skeletal muscle contain 3 types of fibers. What are they?
intermediate fibers
combination of fast and slow fibers.
Red muscles
muscle primarly made up of slow fibers, which have endurance.
White muscles
muscle primarily made up of fast fibers, which have no endurance.
Atrophy
any weakening or degeneration (especially through lack of use)
"All or none principle"
applies to muscle fibers and motor units either it contracts or it doesn't, Either the action potential occurs or it doesn't, this is called the?
triad
2 terminal cisternae and one T-Tubule.
Astrocytes
Abundant star shaped cells found throughout the CNS, cleaning up debris in the extracellular space and removing neurotransmitters from the synaptic cleft, connects neurons to nearby cappilaries, components of the blood-brain barrier
Microglia
Spider-like phagocytes; dispose of debris, smallest neuroglial cells; phagocytic cells that enculf cellular debris, waste products and pathogens. increase in number as a result of infection or injury
Ependymal cells
Type of neuroglial cell found in the ventricles, circulate cerebrospinal fluid
Ogliodendrocytes
Produce myelin sheath around nerve fibers in the central nervous system (CNS)
Satellite cells
Protect neuron cell bodies and provide nutrition to the cell bodies
Schwann cells
Supporting cells of the peripheral nervous system responsible for the formation of myelin. Wrap around one neuron at a time
Nissl substance
specialized rough endoplasmic reticulum for the nerve
Neurofibrils
intermediate cytoskeleton that maintains cell shape, bundles of intermediate filaments (neurofilaments); maintain shape
Dendrites
conduct impulses toward the cell body
Axons
conduct impulses away from the cell body
Synaptic Cleft
gap between adjacent neurons
Synapse
junction between nerves
Nodes of Ranvier
gaps in myelin sheath along the axon
Gray Matter
cell bodies and unmylenated fibers
Nuclei
clusters of cell bodies within the white matter of central nervous system
Ganglia
collections of the cell bodies outside the central nervous system
Sensory neurons
carry impulses from the sensory receptors
Motor neurons
carry impulses from the central nervous system
Interneurons
Found in neural pathways in the central nervous system; connect sensory and motor neurons
Depolarization
a stimulus depolarizes the neurons membrane
Autonomic reflexes
smooth muscle regulation, heart and blood pressure regulation, regulation of glands, digestive system regulation
Somatic Reflexes
activaiton of skeletal muscles
Somatic sensory area
recieves impulses from the body's sensory receptors
Primary motor area
sends impulses to skeletal muscles
Protection of the CNS
Scalp and Skin, SKull and vertebral column, Meninges
Meninges
Dura mater - double-layered external covering (Periosteum and Meningeal Layer)
Periosteum
attached to the surface of the skull
Meningeal layer
outer covering of the brain
Cerebrospinal Fluid
Similar to blood plasma composition, formed by the choroids plexus, forms a watery cushion to protect the brain, circulated in the arachnoid space, ventricles, and central canal of the spinal cord
Concussion
Slight Brain injury; no permanent brain damage
Contusion
Nervous tissue destruction occurs; but does not regenerate
Cerebral Edema
Swelling from the inflammatory response; may compress and kill brain tissue
Cerebrovascular Accident (CVA)
commonly called a stroke, the result of a ruptured blood vessel supplying a region of the brain
Alzheimer's Disease
progressive degenerative brain disease
Peripheral Nervous System (PNS
Nerves and ganglia outside the CNS (everything else)
Mixed Nerves
both sensory and motor fibers
Afferent nerves
carry impulses toward the CNS
Efferent nerves
carry impulses away from the CNS
Cranial Nerves
12 pairs of nerves that mostly serve the head and neck
Spinal Nerves
pair of nerves at each vertebrae for a total of 31 pairs
Autonomic Nervous System
The involuntary branch of the nervous system (divided into Sympathetic and Parasympathetic divisions), the part of the nervous system of vertebrates that controls involuntary actions of the smooth muscles and heart and glands
Sympathetic division
norepinephrine and epinephrine neurotransmitters, Fight-or-Flight, response to unusual stimulus (E's exercise, excitement, emergency, and embarrassment)
Parasympathetic Division
(housekeeping activities) conserves energy, maintains daily nevessary body functions (D's digestion, defecation, and diuresis)
Enteric Division
complex networks of neurons in the digestive tract, pancreas, and gallbladder; normally regulated by the sympathetic and parasympathetic divisions of the autonomic nervous system