HFF 8/29 muscle physio

-voluntary
-very long, multinucleate cells
-not self stimulating (somatic innervation motor unit)
-no rhythmic contractions
-fatigues easily
-striated
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Terms in this set (36)
-voluntary
-very long, multinucleate cells
-not self stimulating (somatic innervation motor unit)
-no rhythmic contractions
-fatigues easily
-striated
traits of skeletal muscle (6)
-involuntary
-striated
-single nucleus, branched cells, intercalated discs
-self stimulating, impulse spreads cell to cell
-rhythmic contractions
-doesn't fatigue
traits of cardiac muscle
-involuntary
-cigar shape nucleus, spindle shape cell
-non striated
-self stimulating
-rhythmic contractions
-doesn't fatigue
traits of smooth muscle
desmosomes, gap junctions (electrical conductance), adherens
intercalated disk composition
L-tyupe calcium channels
What enable Ca2+ exchange in cardiac cells
-large mitochondria to resist fatigue
-high levesl of myoglobin storage for O2
how do cardiac cells avoid risks of only using aerobic respiration (ischemia/hypoxia)
- thin actin fibers attach to cell wall and to dense bodies in cytoplasm
-
Instead of striation, how are smooth muscles organized/structured
Image: - thin actin fibers attach to cell wall and to dense bodies in cytoplasm -
alpha motor neuron + the myofibrils it innervates
what makes up a motor unit
false: each individual muscle fiber is only connected to ONE alpha motor neuron. but one alpha motor neuron can split up to innervate thousands of myofibrils
true or false: each individual muscle fiber is connected to thousands of alpha motor neurons
more and more motor units are activated
motor unit recruitment
z disc to z discWhat determines the length of a sarcomereA) Z disc B) M line C) I band D) A band E) H zonelabel-I band -space between z discs -H zoneon sarcomere diagram, which areas contract?the M lineWhere does the myosin head slide the actin in regards to the sarcomeretrigger depolarization and Na+ to enter, causing an action potential to be created and propagated via muscle plasma membrane potential. T tubule-> Ca release from SR-> Ca binds to troponin which will then unblocks tropomyosin so that ratcheting mechanism can happenWhat will the NT do to the motor end plate?1) binding of myosin to actin (inorganic phosphate is released) 2) power stroke 3) ADP released 4) New ATP allows detachment of myosin head 5) ATP to ADP in cocking mechanismSteps of the cross bridge cycle80-120% lower: 75 maximal: 170What is the optimal operating length of sarcomere? lower limit? maximal limit?Creatine phosphate-1 ATP per CP Anaerobic respiration-2 ATP per glucose Aerobic respiration-38 ATP per glucose3 sources of energy for muscle contraction and corresponding ATP amountKnow this1) multiple motor unit summation: constant intervals, increasing intensity -hits plateau 2) Wave summation: decreasing time intervals, constant intensity - infused tetanus: incomplete relaxation between contractions. Heat generated - tetanus: sustained contraction without relaxation due to actin binding sites continually being exposed2 types of summationRelaxation despite present stimuliFatigueForce exceeds the load; once the peak tension has been reached, muscle shortens with constant loadIsotonic contractionMuscles do not shortenIsometric contractionWhen a muscle contracts not all motor neurons will fire however the more motor neurons that fire the stronger the force of contractionFractionationMotor unit recruitment depends on the demand, for example 'load', motor units are recruited from small to large. This allows for fine-tuning of the muscle contraction for different tasks. Type one, type I + type IIa, type I + type IIa + type IIbHenneman's size principleType I: slow, respond to any load, maintaining posture, i.e. marathons Type IIa: fast, jumping, short distance, running Type IIb: these are recruited when the load becomes even greater.Describe the different types of motor unitsMemorizeSensory receptor - afferent neuron goes to spinal cord - integration center at spinal cord - interneuron- Activate motor efferent neuron- muscle contractionDescribe the pathway for a reflex arcThey can be either. Autonomic would result in activation of cardiac or smooth muscle.Are reflex arcs somatic or autonomic?Muscle spindles-when muscle stretches it causes depolarization It then synapps is at the spinal cord activating the Alpha motor neuron. This then causes the muscle that was stretched to contract in order to resist the stretching. Other antagonist muscles will be inhibited via reciprocal innervation making them relax. I.e. The knee-jerk reflex where the hamstring muscles oppose the quadriceps MONOSYNAPTICDescribe the stretch reflexExtra fusal is the muscle fiber around the muscle spindle. Innervated by alpha motor neurons. Provide force. Interfusal is the muscle fiber of the muscle spindle. These are encapsulated by collagen sheaths. Innervated by gamma motor neurons and group IA and groupII sensory afferentsDifference between intrafusal muscle fibers and extra fusal1- nuclear bag nerve fibers. Detect fast, dynamic changes in muscle length and tension. Group 1aafferents 2- Nuclear chain nerve fibers. Nuclei are in a chain. They detect static changes in length/tension. Innervated by slower group II afferents and group IA afferentsTwo subtypes of intra-fusal fibersThey respond to muscle contraction. They prevent tendon damage by causing the contracting muscles to relax. Causes relaxation by inhibiting the agonist IB motor neuron in the contracting muscle. Different from the other reflex, The antagonist muscle is stimulated to contract.Golgi deep tendon reflex: describeMuscle spindle - group IA and II afferents, gamma motor efferent neurons. ACTIVATES alpha motor neuron Golgi tendon organ: IB sensory afferent fiber, INHIBITS alpha motor neuronSummarize the differences between muscle spindle and Golgi tendon reflex. Image for helpI band and H bandWhich areas of sarcomere shortenKnow this