Term
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Definition
| Cardiac muscle is found only in walls of the heart. |
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Term
| Cardiac Muscle: Structure |
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Definition
The muscle cells (muscle fibers) have cross-striations, and are joined end-to-end in branching networks. At the junction of two cardiac muscle fibers we find a structure called an intercalated disc. Each muscle fiber has a single nucleus.
Proteins: actin, myosin, troponin, and tropomyosin. |
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Term
| Cardiac Muscle: Properties |
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Definition
| Is an involuntary muscle and requires no nervous input to contract. However, in the intact heart, the rate and force by which these contractions occur is increased by sympathetic nerve impulses and the rate is reduced by parasympathetic nerve impulses. |
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Term
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Definition
| Smooth muscle occurs in the walls of the gastrointestinal tract, blood vessels, and many other parts of the body. |
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Term
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Definition
| Smooth muscle fibers are shorter than skeletal muscle and cardiac muscle fibers. Smooth muscle fibers contain actin and myosin arranged in myofibrils that extend along the length of the fibers. They do not have cross-striation and T-tubules. |
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Term
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Definition
| an elongated structure contains my nuclei. This is because during development of the skeletal muscle system, muscle fibers were formed by the fusion of many individual cells called myoblasts |
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Term
Sarcolemma
Sarcoplasm
T-tubels
Sarcoplasm Reticulum |
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Definition
-The plasma membrane of a muscle fiber.
-The cytoplasm of a muscle fiber
The sarcolemma is invaginated at at many points to form structures called transverse tubules or T-tubules
The sarcoplasm contains many mitochondria. The endoplasmic reticulum is called sarcoplasmic reticulum. |
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Term
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Definition
| are composed of thick filaments of myosin molecules and thin filaments of actin molecules of actin. The thin filaments are associated with two other proteins called troponin and tropomyosin. |
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Term
| Skeletal muscle: Properties |
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Definition
| Skeletal muscle enables us to carry out a variety of voluntary movements, to maintain the body'd posture and balance, to produce heat. |
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Term
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Definition
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Term
| Excitation-contraction coupling proteins |
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Definition
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Term
| Sarcomeric skeleton proteins |
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Definition
| - titin is a giant protein expressed in cardiac and skeletal muscle that spans half of the sarcomere from Z-line to M-line. Titin plays a key role in muscle assembly, force transmission at the Z-line, and maintenance of resting tension in the I-band region. |
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Term
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Definition
| another giant protein. its molecule has one end at the Z-line, and the other at the end of the thin filament. Nebulin is not found in cardiac muscle |
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Term
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Definition
| -desmin and microtubules, that maintain the structural order within the cell and connect and connect the cytoplasm and all cellular organelles with the sarcolemma |
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Term
| Membrane-associated proteins |
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Definition
| -Dystrophin, that links the intracellular structural components with those of the extracellular matrix. A mutation in the dystrophin gene causes Duchenne muscular dystrophy. |
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Term
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Definition
The contraction of smooth muscle, cardiac muscle, and skeletal muscle is powered by ATP and has its basis the interaction of actin and myosin.
However, in resting skeletal and cardiac muscle, actin and myosin cannot interact because the mysin binding sites on actin are masked by tropomyosin.
Smooth muscle has actin and mysin, but does not have troponin and tropomyosin. |
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Term
| Myosin procedure (like an oar of a rower) |
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Definition
1) Resting condition, the myosin is primed and ready for action
2) Attachment of myosin head to actin (=dipping oar in water.)
3) Power stroke (= rower pulling on oar).
4) Detachment and reorientation (=rower raises oar and brings it forward again).
5) Preparation and priming for next attachment step
The whole cycle is associated with hydrolysis of ATP to ADP and an inorganic phosphate group. |
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Term
| ATP hydrolysis drives muscle contraction (steps) |
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Definition
1) Resting (ATP has been hydrolyzed to ADP and inorganic phosphate, which remain attached to myosin head
2) Inorganic phosphate dissociates from myosin head - attachment
3 ADP dissociates from myosin head, followed by power stroke.
4) ATP binds to myosin head, followed by detachment and reorientation.
5) ATP is then hydrolyzed to ADP and inorganic phosphate. The myosin molecule is then primed for a return to step 1 and the cycle is repeated. ATP hydrolysis by the myosin head is catalyzed by actin. |
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Term
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Definition
| the muscle that initiates movement. |
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Term
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Definition
| While the prime mover is contracting another muscle is relaxing. |
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Term
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Definition
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Term
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Definition
| is the point about which the lever moves. This is usually the joint |
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Term
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Definition
| The components of this lever system are arranged so that the fulcrum is between the in-force. This is common arrangement for muscles that produce extension of body parts. |
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Term
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Definition
| the components of this lever system are arranged so that the in-force is between the out-force and the fulcrum. This is a very common kind of lever in the body. This arrangement produces flexion of body parts (e.g. flexion of the forearm by the biceps brachii) |
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