Lab 5 Flashcards
Myofibers
Muscle fibers
Plasma membrane of a muscle cell
Sarcolemma
Within the myofibers are
Rod- like structures called myofibrils
Eithin myofibrils are
Long filamentous contractile proteins called myofilaments
Myofilament types
Actin and myosin
Contractile unit of. Muscle cell
Sarcomere
Z disk
Common wall between one sarcomere and the next
How are filaments inside the sarcomere arranged
Myosin inside actin
Where is action potential created
Sarcomere
Contacts and causes the myosin to pull the actin, contracting and shortening the entire muscle cell and thus the muscle
What gives myosin the ability to grab onto actin and pull them inward
Calcium released from the sarcoplasmix reticulum
What is stored in the sarcoplasmic reticulum
Calcium
Fasicle
Rod shaped structure binding the rods of the myofibers, which are building into a whole muscle
Layers of a whole muscle
Endomysium - inside fascicle around each myofiber
Perimysium- along the wall of the fascicle
Epimysium- wall of whole muscle
Tendon
Attaches muscle to bone
Aponeurosis
Broad, flat expanse of a tendon usually attaching two muscles together
Origin and insertion
Origin is the stationary end
Insertion is the movable in
Insertion moves toward origin
Which direction does the axon carry the action potential
Down toward the synapse
Presynaptic terminal
Button like end of neuron is where it communicates with the next cell
(Axon terminal)
Postsynaptic membrane
Membrane that the neuron is interacting with
Synaptic cleft
Space between presumptic terminal and the postsynaptic membrane
Synaptic vesicles
Within the Presynaptic terminal with neurotransmitters
Channels in neuron
Voltage cages ca channels
Causes release of neurotransmitter
Calcium rushing into the terminal causing exocytosis of vescicles
Acetylcholine (ACh)
Neurotransmitter used at the NMJ
Binds to channels on postsynaptic membrane
Channels on postsynaptic membrane in NMJ
Ligand gates Na+ channel for contraction
Enzyme in synaptic cleft that breaks down acetylcholine
Acetylcholinesterase
Things that interfere with NMJ
Botox
Pesticides
Curare
Graded contraction
Contraction of differing strengths
Two ways of achieving graded contraction
Motor unit summation and multiple wave summation
A motor unit is
A single motor neuron plus all of the muscle cells that it innervates
Motor unit ratio
How many musclec Ella thag single motor neuron intervates
1:10 for fine delicate control (eye)
1:1,000 postural (quads)
Motor unit summation
Total force exerted as the combined force of all motor units recruited
Motor unit recruitment
More motor units recruited to achieve a stronger contraction
Maximum strength
All the motor units are active (a set number)
