Unit 3 Flashcards
stationary attachment
point of origin
movable point of attachment
point of insertion
cordlike structure of dense regular connective tissue
-attached muscle to bone, skin, or another muscle
-epimysium+ perimysium+ endomysium
tendon
prime mover; muscles that contracts to produce a movement
agonist
muscle whose contraction opposes that of the agonist
antagonist
muscle that assists agonist by contributing tension or stabilizing point or origin (acting as fixators)
synergist
indicates muscle’s primary action
ex: flexor digitorum longus flexes digits
muscle action
indicates muscle location
ex: rectus femoris is near the femur
specific body region
indicates origins and/or insertions
ex: sternocleidomstoid originates on the sternum
muscle attachment
indicates organization of muscle fascicles
ex: rectus abdominis is composed of fibers running in vertically straight orientation
orientation of muscle fibers
ex: deltoid is shaped like a triangular delta symbol
muscle shape
ex: gluteus maximus is the largest of the buttocks muscles
muscle size
indicates number of muscle bellies or heads each contains at the superior or proximal attachment site
ex: triceps brachii has three heads
number of muscles heads at an attachment site
types of muscle tissues:
- skeletal
- cardiac
- smooth
functions of skeletal muscles
- movement
- posture
- protection
- regulation
- heat
characteristics of skeletal muscles
- excitability
- conductivity
- contractility
- elasticity
- extensibility
ability to respond to a stimulus by changing electrical membrane
excitability
sending of electrical signal or change down the length of the cell membrane
conductivity
enables a muscle to cause movemement
contractility
ability of a muscle to turn back to its original length
elasticity
ability of a muscle to be stretched
extensibility
dense irregular connective; outer layer of connective tissue that wraps around the skeletal muslce
epimysium
wraps around each fasicle
perimysium
muscle fiber bundles
fascicles
wraps around each muscle fibers
endomysium
thin, flattened sheet of dense irregular tissue
aponeurosis
immature muscle cell
myoblasts
helps maintain the shape of a muscle fibers
satellite cell
composed of thick and thin myofilaments
myofibrils
allows for electrical signals to spread deep within a fiber
transverse tubules (t-tubules)
serves as reservoir, holds calcium
sacroplasmic reticulum
plasma membrane, wraps around entire muscle fiber
sacrolemma
function unit of skeletal muscle; myofilaments arranged in repeating units
sacromere
consist of bundles of myosin proteins
thick filaments
twisted strands of protein strands, contains protein actin
thin filaments
specialized protein structures that anchor in thin filaments
Z disc
attachment site for thick filaments
M line
where thick and thin filaments don’t overlap, only contains thin filaments
I band
regions of overlapping thick and thin filaments
A band
no overlapping of filaments, only contains thick filaments
H zone
multi complex protein structure that binds calcium
troponin
-type of synapse
-site where an axon of motor neuron and skeletal muscle fiber interact
-skeletal muscle fibers contract only when stimulated by a motor neuron
-parts: motor neuron, motor end plate, synaptic cleft
neuromuscular junction (NMJ)
segment of muscle fiber that forms synapse with motor neuron
motor end plate
difference in charge on one side of the motor end plate and the other side of the motor end plate
end plate potential
events of the neuromuscular junction:
- nerve impulse that comes from the spinal cord
- nerve reaches synaptic end bulb (terminal end of motor neuron) and triggers opening of calcium channels
- calcium moves down concentration gradient inside terminal end
- calcium will trigger packaging and mobilization of synaptic vesicles
- synaptic vesicles fuse with membrane at terminal end and then rupture releasing neurotransmitters into synaptic cleft
- neurotransmitter binds to specialized gated channels
- channels open and sodium (positive charge) moves down its concentration gradient
chemical messengers
ex. acetylcholine
neurotransmitters
-when sacromeres shorten, thin filaments slide past thick filaments
-thin and thick filaments do not change length
-overlap between filaments increase
sliding filament model of muscle contraction
steps of crossbridge:
- formation; enzymes cleave off final phosphate -> energy release
- myosin head springs up making contact with thin filament; enzyme comes and cleaves off ADP releasing energy and creating power stroke
- ATP binds myosin, causing detachment of myosin from actin; cross bridge dissociates
- ATP hydrolysis occurs, cocking myosin head
- repeat
breaks bond between myosin head and thin filament
ATP (in crossbridge)
-during neuromuscular stimulation is released from the sacroplasm reticulum
-circulates and makes it way down to the troponin
-as binding happens, binding sites for myosin heads are uncovered
calcium (in crossbridge)
single, brief contraction period and then relaxation period of a skeletal muscle in response to a single stimulation
twitch
force exerted by unit of cross sectional area on object in order to oppose a force called the load; when the myosin heads bind to thin filament
tension
has to do with coupling of the events taken place in neuromuscular junction
latent period
motor neurons and skeletal muscle fibers they innervate
motor unit
sends out signals to skeletal muscles; stimulates activity
motor neuron
-continuous and passive partial contraction of the muscle
-muscle’s resistance to passive stretch during resting state
-do not generate enough tension for movement
-involuntary/stabilize
muscle tone
-muscle produces internal tension, but external resistance causes it to stay the same length
-important in postural muscle function and antagonistic muscle joint stabilization
isometric muscle contraction
muscle changes in length with no change in tension
isotonic muscle contraction
muscle shortens as it maintains tension
concentric contraction
muscle lengthens as it maintains tension
eccentric contraction
-small diameters, many large mitochondria appear red due to large amounts of myoglobin
-ATP generated mainly through aerobic respiration
-develop tension slowly
-resist fatigue
-capable of prolonged and sustained contraction
-muscle fibers associated with isometric postural function
slow oxidative fibers
-intermediate in diameter
-large amounts of myoglobin and appear red
-ATP generated through aerobic respiration and glycolysis
-moderately resistant to fatigue
-muscle fibers associated with large motor skills
fast oxidative fibers
-large and white (no myoglobin)
-large amount of glycogen
-ATP generated through glycolysis
-fatigues rapidly
-contract and relax quickly, providing a short surge of power
fast glycolytic fiber
functions of nervous system:
- collect information
- processes and evaluate information
- initiate response to information
receptors detect stimuli and send sensory signals to spinal cord and brain
collect information
brain and spinal cord determine response to sensory input
processes and evaluate information
brain and spinal send motor output via nerves to effectors (muscles or glands)
initiate response to information
brain and spinal cord
central nervous system
cranial nerves and spinal nerves
peripheral nervous system
input; detects stimuli and transmits information from receptors to the CNS
sensory nervous system
output; initiates and transmits information from the CNS to effectors (aka target)
motor nervous sytem
sensory input that is consciously perceived from receptors (i.e. eyes, ears, and skin)
somatic sensory
sensory input that is not consciously perceived from receptors of blood vessels and internal organs (i.e. heart)
visceral sensory
motor output that is consciously or voluntarily controlled; effector is skeletal muscle
somatic motor
motor output that is not consciously or is involuntarily controlled; effectors are cardiac muscle, smooth muscle, and glands
autonomic motor
neuron characteristics:
- excitability
- conductivity
- secretion
- extreme longevity
- amitotic
receives information from neighboring neurons; receptive ends of neurons
dendrites
where the neuron cell body transitions into axon
axon hillock
bridges the gap between sensory and motor neurons; most abundant
interneuron
afferent
sensory neuron
efferent
motor neuron
-nonexcitable
-smaller
-mitosis
-protect and nourish neurons
-types: oligodendrocyte, astrocyte, ependymal, microglial
glial cells (neuroglia)
-myelinates and insulates CNS axons
-allows faster action potential propagation along axons in CNS
oligodendrocytes
-helps form the blood brain barrier
-regulates interstitial fluid composition
-provides structural support and organization to the CNS
-assist with neuronal development
-replicates to occupy space of dying neurons
astrocyte
-lines ventricles of brain and central canal of spinal cord
-assists in production and circulation of cerebrospinal fluid (CSF)
ependymal
-phagocytic cell that moves through the CNS
-protects the CNS by engulfing infectious agents and other potentially harmful substances
microglial
process of wrapping an axon with myelin
-myelin: several layers of membrane of glial cells
myelination
the energy to do stuff; difference between extracellular and intracellular
potential
electrical charge difference at the membrane
membrane potential
the electrical charge difference at the membrane when cell is at rest
-occurs in entire neuron
-distribution in ions across the membrane
-negative charge due to proteins inside cell
-membrane only allows slow leak of ions
resting membrane potential
binding of neurotransmitter released from presynaptic neurons; production of graded protentials
receptive segment
summation of graded potentials; initiation of action potential
initial segment
propagation of action potential
conductive segment
action potential causes release of neurotransmitter
transmissive segment
steps of an excited neuron:
- nerve impulse arrives at the synaptic bulb
- packaging of neurotransmitters/packaging synaptic vesicles
- synaptic vesicles via exocytosis bud with membrane and release neurotransmitters
- neurotransmitter makes its way across the synaptic cleft binding postsynaptic neuron and ligand-gated channels
- ligand gated channels then open up-> increasing permeability across the membrane
- sodium (example) will move down its gradient inside the postsynaptic neuron
can increase strength, can increase the amount of ions inside membrane; can stimulate neurons and multiple sites
graded response
responds to changes inside the cell; normally closed, but open when membrane charge changes
voltage gated ion channel
once channels are in the refractory period they will remain shut-> prevents sodium from moving back in the opposite direction towards the axon hillock
back propagation
-occurs in neuron’s receptive region due to ion flow through chemically gated channels
-can be positive or negative changes in charge
-are graded: have larger potential change to stronger stimulus
-are local (travel only a short distance)
graded potentials
-occur on neuron’s conductive region (axon) due to ion flow through voltage gated channels
-involve depolarization (Na+ in) then repolarization (K+ out)
-are all or none once threshold is reached
-propagate down entire axon to synaptic knob
action potentials
-proteins pores in the membrane that allow ions to move down their concentration gradients (into or out of the cell)
channels
always open for continuous diffusion
leak (passive) channels
normally closed, but open when neurotransmitter binds
ligand (chemically) gated channels
