Chapter 11: The Musculoskeletal System Flashcards
Which zone or band in the sarcomere does NOT change its length during muscle contraction? Why?
The A-band does not change length during muscle contraction because it is the entire length of the myosin filament. The filaments do not change length, but rather slide over each over; thus, the A-band should remain a constant length during contraction.
What are the events that intiate muscle contraction, in order? Start with neurotransmitter release and trace the pathway to the point where myosin binds with actin.
- Release of acetylcholine from motor neuron
- activation of acetycholine recepors in sarcolema
- depolarization of sarcolema
- spreading of signal using T-tubules
- release of calcium from sarcoplasmic reticulum (SR)
- binding od calcium to troponin
- conformational shift in tropomyosin
- exposure of myosin-binding sites
- myosin binds to actin
What roles does the binding of ATP to myosin head play in the cross-bridge cycle? What about the dissociation of ADP and inorganic phosphate from the myosin head?
- Binding of ATP
- Dissociation of ADP and inorganic phosphate
- Binding of ATP
- ATP binding allows the myosin filament to disconnect from actin.
- Dissociation of ADP and inorganic phosphate
- Causes th power stroke
What is tetanus (the physiological phenomenon, not the disease)
Tetanus os the summation of multiple simple twitches that occur to quickly for the muscle to relax. This leads to a stronger and more prolonged contraction of the muscle.
What are the three types of muscles?
- Skeletal
- Smooth
- Cardiac
____ is responsible for voluntary movement and is therefore innervated by the somatic nervous system?
Skeletal Muscle
What are the types of fibers in skeletal muscles?
Slow-twitch fibers (Red fibers)
Fast-twitch fibers (White fibers)
Slow twitch fibers
Have high myoglbin content and primarily derive their energy aerobically. Also contain many mitochondria to execute oxidative phosphorylation.
Muscles that contract slowly, but that can sustain activity (such as the muscles that support posture).
Myoglobin
Ocygen carrier that uses iron in a heme group to bind oxygen, imparting a red color.
Fast-twitch fibers
contain much less myoglobin. Thats why they appear white.
Muscles that contract rapidly, but fatigue quickly.
____ muscle that is responsible for involuntary action?
Smooth
What is special about smooth and cardiac muscles?
Myogenic Activity
They can contract without nervous system input.
____ muscle has charectristics of both smooth and skeletal muscle?
Cardiac
Cardiac muscle cells are conneted by ____, which contain many ____.
Intercalated discs
Gap Junctions
____ is the basic contractile unit of skeletal muscle?
Sarcomere
What are sarcomenres made up of?
Thick and Thin filaments.
What are they made up of
Thick Filaments
Thin Filaments
Thick Filaments: bundles of myosin
Thin Filaments: bundles of actin with two proteins names Troponin and Tropomyosin.
MNEMONINC
To remember which filament is asociated with troponin and tropomyosin.
Remeber that actin has a T in it.
MENMONIC
To remeber which is the thin and thick filament.
Remeber Actin: Acthin
The sarcomere Anatomy
- Z
- M
- I
- H
- A
- Z: Z is at the end of the sarcomere (Z is at the end of the alphabet)
- M: Middle of the Myosin filaments
- I: I is a thin letter (Thin filaments only)
- H: H is a thick letter (Thick filaments only)
- A: All of the thick filament, whether or not it is overlapping.
_____ is a modified endoplasmic reticulum that contains a high concentration of Ca2+ ions.
Sarcoplasmic Reticulum
A myofibril is _____. A muscle fiber (or myocyte, or muscle cell) contains ____. A muscle is made up of ____.
A myofibril is an arrangement of many sarcomeres in series. A muscle fiber (or myocyte, or muscle cell) contains many myofibrils within it, arranged in parallel. A muscle is made up of parallel muscle fibers.
Sliding filament model and steps
- ATP is hydrolyzed
- Ca2+ binds to troponin; myosin binds to actin
- Powerstroke occurs; the sarcomere contracts; ADP and Pi dissociate from myosin.
- New ATP binds to m yosin, causing detachment of myosin from actin; hydrolysis of ATP to ADP and Pi causes reckoing of the myosin head.
Troponin vs Tropomyosin
Tropoin: involved in the muscle contraction
Tropomyosin: wraps around
Rigor Mortis
After deatj, ATP production ceases. Myosin heads cannot detach from actin, making it impossible for muscles to relax and lengthen.
Muscles cells exhibit what type of response?
All or nothing
Either they respond completely to a stimulus or not at all.
What type of energy reserve do we use to quickly generate ATP? Like for sprinting
Creatine Phosphate
As exercising muscles run out of oxygen, they must use ___.
What about Slow Twitch fibers?
What about Fast Twitch fibers?
- Myoglibin reserves to keep aerobic metabolism going.
- Have fewer mitochondria and must rely on glycolysis and dermentation to make ATP under most circumstances.
What happens when muscle use eventually overwhelm the baility of the body to deliver oxygen? Last Resort
The even the Slow Twitch fibers (Red) must swtitch to anaerobic metabolism and produce lactic acid, at which point in the muscles begins to fatigue.
What is the difference between compact bone and spongy bone?
- Compact Bone
- Spongy Bone
- Compact Bone
- Dense and is used for its strength, it forms most of the outer layers of a bone.
- Spongy Bone
- Has many spaces between bony spicules called trabeculae ad it the site of marrow production. It is found in the inner core of the bone and also helps distribute forces or pressures on the bone.
What are the three structural parts of a bone? Which part contributes most to linear grorth?
- Diaphysis
- Metaphysis
- Epiphysis
- Growth plates are found in the epiphyses and contribute to linear growth.
What chemical forms most of the inorganic component of the bone?
Most inorganic bone is composed of hydroxyapatite crystals.
What are the functions of
- Osteoblast:
- Osteoclast:
- Chindrocyte:
- Osteoblast: Build Bone
- Osteoclast: Chew bone (break it down)
- Chondrocytes: Form cartliage
What liquid provides the lubricaton for movable joints? What tissue produces it?
- Synovial fluid
- The Synovium
