Muscle Tissue Ch.10
What are the functions of the skeletal system?
-Produce skeletal movement -Maintain Posture and body position -Support Soft Tissues -Guard Entrances and Exits -Maintain Body Temporature -Store Nutrient Reserves
What is and how rigor mortis happens?
-Rigor mortis occur when cross bridges of actin and myosin can't break apart. -After death, rigor mortis sets in, where the muscles contract and the limbs of the corpse become stiff because calcium leaks out of the sarcoplasmic reticulum. -begins 2-7 hours after death, last 1-6 days. After that it begins to decompose.
What are the components and functions of thick filaments?**
-Type of myofilaments: -Primarily made of the protein myosin-(Myosin have a long tail and a short head that are connected by a hinge area) -Thick filaments are found in the dark A band in the sarcomere -Has a core of titan -properties of elasticity and contractibility Responsible for muscle contraction
What is a triad?
-combination of a pair of terminal cisternae plus a T tubule. -membranes of triad are tightly bound together but their fluid contents are separate and distinct.
What are the components of a sarcomere?
-repeating functional units -smallest unit of muscle fiber -composed of Thin and Thick filaments; proteins that stabilize the positions of thick/thin filaments; and proteins that regulate interactions between thick/thin filaments -Dark bands called A bands and light ones called I bands -responsible for muscle contraction
What events lead to muscular contraction? p.g 297
1. ACh is released by synaptic terminal at the NMJ , binding to receptors on sarcolemma 2. Action potential reaches T tubule b/c of change in trans membrane potential in muscle fiber 3. Sarcoplasmic reticulum releases stored Ca2+ in/around sarcomeres 4. Calcium ions bind to troponin, producing a change in the orientation of the troponin-tropomyosin complex that exposes active sites on the thin (actin) filaments. Cross-bridges form when myosin heads bind to active sites on actin 5. Contraction begins, repeated cycle of cross bridge binding, powered by the hydrolysis of ATP.
What are the differences between Skeletal, Cardiac, and Smooth muscle fibers?
1. Skeletal muscle tissue. Multinucleate striated fibers under voluntary control -Cells are long, cylindrical, striated, and multinucleate. -LOCATIONS: Combined with connective tissues and neural tissue in skeletal muscles -FUNCTIONS: Moves or stabilizes the position of the skeleton; guards entrances and exits to the digestive, respiratory, and urinary tracts; generates heat; protects internal organs 2. Cardiac muscle tissue. Branched striated fibers under involuntary control. -Cells are short, branched, and striated, usually with a single nucleus; cells are interconnected by intercalated discs. -LOCATION: Heart -FUNCTIONS: Circulates blood; maintains blood (hydrostatic) pressure 3. Smooth muscle tissue. Non-striated spindle shape fibers under involuntary control. -Cells are short, spindle-shaped, and nonstriated, with a single, central nucleus. -LOCATIONS: Found in the walls of blood vessels and in digestive, respiratory, urinary, and reproductive organs -FUNCTIONS: Moves food, urine, and reproductive tract secretions; controls diameter of respiratory passageways; regulates diameter of blood vessels
what does the epimysium, perimysium and endomysium cover?
1.Organization of Connective Tissues a.Muscles have three layers of connective tissues -Epimysium (dense membrane) covers the entire muscle fiber. -Perimysium (intermediate membrane) covers fascicles of muscle fibers and contains the blood vessels and nerves -Endomysium (thin membrane) covers individual muscle fibers ii. All three layers fuse at the end of muscles to form tendons or aponeurosis to bind muscles to the skeleton.
What events lead to muscular relaxation?
6. ACh is broken down by AChE-ending action potential in sarcolemma 7. SR recaptures/reabsorbes Ca2+, concentration of Ca2+ declines 8. Ca+ concentration levels out, troponin-tropomyosin complex returns to normal. Change re-covers active sites and prevents further cross-bridge interaction 9. Contraction ends b/c of no cross-bridge interactions. 10. Muscle relaxation occurs and muscle returns to resting length.
What is aerobic metabolism?
Is the primary energy source of resting muscles Breaks down fatty acids Produces 34 ATP molecules per glucose molecule provided 95% of ATP demands to a resting cell
What are the components and functions of thin filaments?**
Primarily made of the protein actin Thin filaments are found in the light I band in the sarcomere F-actin (filamentous actin) Nebulin Tropomyosin Troponin -interactions between thick and thin filaments results in muscle fiber contraction.
What is recruitment?
The increase in muscle tension that is produced by increasing the number of active motor units
What is glycolysis?
The primary energy source for peak muscular activity Produces two ATP molecules per molecule of glucose Breaks down glucose from glycogen stored in skeletal muscles
What is a motor unit?
in a skeletal muscle: Contain hundreds of muscle fibers that are controlled by a single motor neuron and contract at the same time. Motor units create tension in muscles.
What is isometric contraction?
muscle contracts but does not shorten. Force cannot move the load.
What is isotonic contraction?
muscle contracts, shortens, and creates enough force to move the load
What is the function of the sarcoplasmic reticulum? ** http://www.ask.com/question/function-of-sarcoplasmic-reticulum
release during conctraction and re-absorption of calcium ions during relaxtion. pg. 284, 297 has pic.
What are the components of the neuromuscular junction?
synaptic terminal, muscle fiber, motor end plate and synaptic cleft
What are the major types of muscle fibers?
• Fast fibers --- are large in diameter; they contain densely packed myofibrils, large amount of glycogen, and relatively few mitochondria. Most of the skeletal muscle fibers are fast ones. Can reach peak tension in 0.01 sec. or less • Slow fibers --- are about half the diameter of fast fibers. Takes 3x as long to reach peak tension. Slow fibers are specialized to enable them to contain contracting for extended periods, when the fast fibers have become fatigued. Slow fibers have red pigment (myoglobin) containing O2. •Intermediate fibers ---little myoglobin and relatively pale, have intermediate capillary network and mitochondrial supply.
