Muscular system Flashcards
Each muscle fiber (Motor unit) is under control of _____ neuron
One
What are the three types of muscle? Which two are striated?
Skeletal and cardiac are striated
Smooth
Type of muscle that is voluntary, neurogenic, controlled by somatic nervous system. Striated
Skeletal muscle
Type of muscle that is involuntary, myogenic (comes from the muscle itself), autonomic nervous system, Striated
Cardiac
 works just like skeletal mechanically
Type of muscle that is involuntary, Nuro or myogenic, controlled by autonomic nervous system. Involves a very different mechanism than the other two types of muscle
Smooth muscle
Lines blood vessels, Gut, uterus, iris of the eye
Skeletal muscle is the effector of the _________ nervous system
Somatic
What is the functional unit of skeletal muscle?
Myofibrils! (Myofilaments?) and sarcomere??
The thin filament includes….
- F-actin
- tropomyosin (push off myosin Bridge site?)
- Troponin (includes three proteins, [calcium binding site, actin, tropomyosin]
Active site is the ________ binding site
Myosin
What covers the myosin binding sites?
Tropomyosin
The thick filament is made of _______ molecules arranged like many golf clubs together. 
Myosin
What are the different parts of a myosin molecule?
- myosin tail
- actin binding site (myosin head)
- ATPase site (myosin head)
There’s a hinge in between the myosin tail and head
The area of overlap of thick and thin filaments is called…
A-band
The end of the sarcomere. Anchors thin filaments
Z disc
This band only includes thin filament
I-band
During muscle contraction, the ____ band disappears, and the _____ band remains the same. 
I band
A band
This is a series of sarcomeres attached end to end (sarcomere in series)
Myofibril***
Thick filaments lined by accessory proteins
M line?
When looking at a light microscope image of skeletal muscle fiber the light area is _____ and the darker bands are ______ 
I band
A band
Thin (_______) filament
Thick (_______) filiment
Actin
Myosin
This area is only thick filaments
H zone (don’t need to know For test?)
Muscle fiber is…
Muscle Cell (The entire cell)
What is the sarcolemma?
Plasmalemma or the cell membrane
Invagination of sarcolemma forming a network of tubes around the myofibrils and it associates with Sarcoplasmic reticulum
T-Tubule
 what is the Sarcoplasmic reticulum?
Smooth endoplasmic reticulum (smooth E.R.)
(almost all smooth ER stores calcium ions)
Scarcoplasm =
Cytoplasm
- nuclei and mitochondria pushed off to the side
- filled with parallel arranged myofibrils
Named at the gross level
Parallel arranged muscle fibers
Whole muscle (The muscles that you have heard of by name ex: bicep)
Three levels of connective tissue coverings are…
All three merge at ends to form….
- endomysium
- Perimysium
- Epimysium
All three merge to form tendons
The first level of connective tissue covering, delicate covering that covers each muscle fiber
Endomysium
Second level of connective tissue covering that forms a bundle of muscle fibers called a fasicle
Perimysium
Third level of connective tissue covering that forms a bundle of fascicles we call whole muscle
Epimysium
Everything that happens from action potential on the motor neuron until the muscle contracts….
Neuromuscular junction and excitation-contraction coupling??? (Look this one up) 
Motor end-plate
Sarcolemma of neuromuscular junction?
This is at the end of the Nurotransmitter chain
What kind of receptors are found here?
Neuromuscular junction or Nuroeffector junction
ACh receptors (nicotinic cholinergic receptors)
What are the seven steps of EC coupling? 
- AP arrives at neuromuscular junction
- AP triggers opening of voltage gated calcium channels in axon terminal, calcium triggers exocytosis of ACh
- ACh diffuses across the synaptic cleft and binds to ACh receptors
- ACh Opens the sodium channel and sodium diffuses in and depolarizes motor end plate to threshold which triggers an AP
- AP Travels along sarcolemma and down the T-tubules
- AP is “ transferred” to the SR where it triggers calcium release
- Calcium binds to Triponin, triggered muscle contraction. Relaxation —> stop AP on neuron, stop muscle AP, stop releasing calcium
* calcium is quickly pumped back into the SR and the muscle relaxes
The crossbridge cycle is the mechanism that underlies the …
Sliding filament theory
What is needed for the cross bridge cycle?
- ATP
- calcium
What causes rigor mortis?
When an animal dies, calcium leaks out in there is no ATP to release the cross bridge
Explain the steps of the Crossbridge cycle
- Myosin head attaches to the actin myofilaments, forming a cross bridge. (Myosin head is in a high energy/affinity configuration)
- Inorganic phosphate generated in the previous contraction cycle is released, initiating the power stroke. The myosin head pivots and bends as it pulls on the actin filament, sliding it towards the M line. Then ADP is released. 
- As new ATP attaches to the myosin head, the link between myosin and actin weekens, and the cross bridge detaches (myosin head is in low affinity/energy configuration)
- As ATP is split from ADP and P, the myosin head is energized (cocked into the high energy/affinity confirmation
* look at the Cross bridge cycle picture
