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Chapter 6 Human Biology
Terms in this set (24)
Review the 3 main types of muscle tissues from Chapter 4
Smooth-located in walls of hollow visceral organs, except the heart, appear spindle-shaped, and are also under involuntary control
Skeletal-occur in muscles which are attached to the skeleton.
Cardiac muscle cells-located in the walls of the heart, appear striated, and are under involuntary control.
What is a muscle fiber equivalent to?
What attaches a muscle to bone?
the structure of a muscle from large to smaller structures: muscle, fascicles, muscle fiber, myofibrils, sarcomeres, myofilaments (actin and myosin).
*check notes from 10/10
What is the contractile unit of a muscle?
What two proteins are sarcomeres made up of?
actin and myosin
What are the repeating units in a myofibril?
Which protein in a sarcomere has heads on it that can be used for attachment (think golf clubs)?
explain muscle contraction from beginning to end in order.
1.) An action potential in a motor neuron causes acetylcholine to release in the synaptic cleft.
2.) Acetylcholine binds with receptors on the cell membrane on the muscle fiber, opening Ca2+ -Na+ channels. Usually referred to as Calcium channels.
3.) Calcium is released from the terminal cisternae into the muscle fiber.
4.) Calcium binds to troponin
5.) Troponin shifts tropomyosin, which was blocking the active site on the actin.
6.) Myosin heads attach to actin by breaking down ATP to ADP and a phosphate via Myosin-ATPase
7.) The Myosin head forms a 'cross-bridge' on the active site of the actin filament.
8.) The cross bridge pulls actin, which slides over the myosin - known as the 'Power Stroke.'
9.) The release of ADP completes the cross-bridge movement and ATP attaches to myosin, breaking the actin-myosin crossbridge.
10.) Every time ATP is split into ADP + P, the myosin head 'cocks' into place to form another cross bridge with actin.
What is the role of acetylcholine in muscle contraction? Calcium? Myosin? ATP?
-Acetylcholine binds to muscle fiber and stimulates contraction.
-Without calcium the myosin binding sites will not open.
-ATP needed for actin to attach and un-attach. -Myosin heads pull actin
What is a crossbridge? What molecule allows crossbridges to be made and broken?
When Myosin heads attach to actin. ATP allows cross-bridges to be made and broken
Where does calcium come from in the muscle fiber/cell? (where is it stored)
Calcium comes from the sarcoplasmic reticulum and it is stored in the smooth endoplasmic reticulum
What molecule does calcium bind to and what is the result?
Troponin- causing tropomyosin o shift from the face of the actin filaments to which myosin has need to bind to produce contraction
In the sliding filament model of muscle contraction (this is how we discussed the interaction of myosin and actin) does the movement of actin or myosin actually shorten the sarcomere so that the muscle fiber shortens etc....?
yes. (check notes from 10/10)
Explain muscle relaxation.
a bundle of long slender cells (muscle fibers) that have the power to contract and hence to produce movement. Muscles are responsible for locomotion and play an important part in performing vital body functions. (check with gabby)
Why does rigor mortis occur?
• Ca++ leaks out of cell
• Ca++ binds to troponin
• Tropomyosin moves and myosin/actin bind
• Heads get stuck @ 45 degrees b/c there's no ATP to release heads
• Muscles are stuck in contraction
Name the two types of muscle fibers. Which is used for endurance? Which is used for quick bursts of energy?
Fast twitch-quick bursts
fast twitch vs slow twitch
What gives slow-twitch fibers their darker color?
It has more blood vessel in them
Anaerobic training increases the size, mass and strength of a muscle. What is increasing in the muscle cells that allow this to occur in this type of training?
Do muscles get larger by making more muscle cells? Explain.
No. Overall you are making your cells better, you are not adding more. When your muscles are done growing the muscle cells do not divide.
When you aerobically train what are you increasing in your muscles and your muscle cells?
capillaries, mitochondria, myoglobin
Why is cardiac muscle striated like skeletal muscle is? Why doesn't smooth muscle look striated (stripes/lines) under a microscope? What's different?
It is also made of Actin and Myosin along with sarcomeres.
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