Chapter 8 Muscle Tissue Flashcards
What are the 5 properties of muscles?
- Excitability - respond to chemicals released from motor neurons
- Conductivity - ability to propagate electrical signals over membrane
- Contractility - ability to shorten and generate force
- Extensibility - ability to be stretched without damaging the tissue
- Elasticity - ability to return to original shape after being stretched
Which of the following characteristics do neurons and muscle cells share?
A. Extensibility
B. Excitability
C. Contractility
D. Elasticity
B. Excitability
What are the three types of muscles?
- Skeletal -Voluntary, Striated, Multinucleate, Attached to bone, skin, or fascia
Cardiac - Involuntary, Striated, Mononucleate, Autorhythmic (can self regulate beat)
Smooth - Involuntary, Non-striated, Mononucleate, Hair follicles, walls of hollow organs
Skeletal Muscle Terminology
What is a muscle?
A group of fasicles
Skeletal Muscle Terminology
What are fasicles?
A group of muscle of cells(fibers)
Skeletal Muscle Terminology
What are muscle cells?
Long bundles of protiens (myofibrils)
Skeletal Muscle Terminology
What are myrofibrils?
Organized into sacomeres (contractile unit of muscles)
What are sarcolemma and sarcoplasm?
Sarcolemma - muscle cell membrane
Sarcoplasm - cytoplasm of a muscle cell
What is inside the sarcoplasm?
Myofibrils - long bundles of proteins
Myoglobin - stores oxygen for use
Glycogen - A polymer of sugar
What are tube-like structures which penetrate the interior of the cell of the sarcolemma?
Transverse tubules (T-tubules) - filled with extracellular fluid
What is the Sarcoplasmic reticulum?
- muscle cell ER
- Terminal cisternae - sacs of the SR, closely associate with T-Tubules
- Storage area for calcium ions IN the muscle cell.
What are the three types of myofilaments(protiens) and what do they form?
- Thick filaments myosin protein
- Thin filaments actin protein
- Elastic filaments titin protein
- Together they form the sarcomere or the contractile unit
What are the functions/structures of the Thick filaments of myofilaments?
- Many myosin protein
- A single myosin is shaped like a golf club (head is mobile), two twist together to make dimer (dimer = two units)
- A thick filament consists of hundreds of myosin dimers
- Binds and hydrolyzes ATP
What are the functions/structures of the Thin filaments of myofilaments?
- Two chains of actin proteins, tropomyosin and troponin
- Each actin unit (red ball) has an active site that can bind to the head of a myosin protein
- Tropomyosin (white stripe) blocks the active site of myosin in relaxed muscles
- Troponin (yellow) binds tropomyosin. In the presence of calcium, troponin moves tropomyosin off active sites of actin
Which of the following molecules is the largest?
A. Myofilament
B. Myofibril
C. Myosin
D. Troponin
B. Myofibril