Chapter 10 Muscle Tissue
Terms
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- What are the four basic functions of the muscular system?
- motion, movement of subtances with the body, stabilizing body position and regulating organ volume, thermogenesis
- shivering
- involuntary contractions of the skeletal muscle
- List 5 characteristics of muscle tissue.
- excitability, conductivity, contractility, extensibility, elasticity
- excitability
- ability to respond to certain stimuli by producing electrical signals called action potentials.
- conductivity
- the ability to conduct action potentials along the plasma membrane
- contractibility
- the ability of muscle tissue to shorten and to thicken, thus generatig force to do work.
- extensibility
- capacity in muscle to be extended without damaging tissue
- elasticity
- muscle’s capacity to return to its original shape after contraction or extension--recoil
- fascia
- a sheet or broad band of fibrous connective tissue deep to the skin or around muscles and other organs of the body.
- superficial fascia (subcutaneous layer)
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- is immediately deep to the skin
- composed of aereolar connective tissue and adipose tissue - What are 4 functions of superficial fascia?
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- stores water and fat.
- reduces the rate of heat loss
- provides mechanical protection against traumatic blows.
- provides a framework for nerves and blood vessels to enter and to exit muscles. - deep fascia
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is composed of dense irregular CT and lines the body wall and limbs
also holds muscles together, separating them into functional groups - Whate are the functions of deep fascia?
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- allows free movement of muscles
- supports nerves, blood vessels and lymphatic vessels
- fills spaces between the muscles - Explain motion as a function of muscle tissue
- movements such as walking or running
- Movement of substances within the body
- All three types of muscle tissue help moves substances such as blood, flood, sperm, ova, and urine.
- Stabilizing body positions and regulating organ volume.
- Skeletal muscle contractions maintain stable body positions and posture. Sustained and contractions of smooth muscles nlock exit of food from the stomach and urine from the urinary bladder for temporary storage.
- Thermogenesis
- Skeletal muscle contractions may generate 85% of all body heat to help maintain normal body temperature.
- epimysium
- is the outermost layer of dense irregular connective tissue that encircles the whole muscle
- perimysium
- surrounds bundles of 10-100 muscle fibers called fascicles
- fascicles
- small bundles or clusters of muscle cells/fibers
- endomysium
- penetrates into the interior of each fascile separating individual muscle fibers from one another
- tendon
- When all three levels of connective tissue mentioned above, the epimyseum, the perimyseum, and the endomyseum extend beyond the muscle fibers and form a dense cord of connective tissue that enables the attachment of muscle to the periosteum of the bone. Ex: calcaneal tendon of the calf muscle.
- aponeurosis
- when the connective tissue elements forming a tendon, extend as a broad flat layer ex: aponeurotica on top of the skull
- Starting with the connective tissue that surrounds individual muscle fiber, list the connective tissue layers in order.
- endomysium, perimysium, epimysium, deep fascia, superfical fascia
- motor unit
- a motor neuron plus all the skeletal muscle fibers it stimulates
- neuromuscular junction
- the type of synapse formed between a motor neuron and a skeletal muscle fiber
- Describe the process by which a motor neuron communicates with a muscle cell.
- The interface between a motoneuron and muscle fiber is a specialized synapse called the neuromuscular junction. Upon adequate stimulation, the motoneuron releases a flood of neurotransmitters that bind to postsynaptic receptors and triggers a response in the muscle fiber. In invertebrates, depending on the neurotransmitter released and the type of receptor it binds, the response in the muscle fiber could either be excitatory or inhibitory.
- What neurotransmitter is released at the neuromuscular junction?
- acetylcholene (AcH)
- motor end plate
- the region of the muscle fiber plasma membrane that is adjacent to the axon terminals.
- List the structural organization of a skeletal muscle from superficial to deep.
- skeletal muscle, fascicle, muscle fiber, myofibril, thin and thick filaments
- Describe the components of a muscle fiber/myofibril.
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sarcolemma: the plasma membrane of a muscle fiber
sarcoplasm: the muscle fiber's cytoplasm
sarcoplasmic reticulum: a fluid-filled system of cisterns which encircles each myofibril - Myofibrils are composed of what?
- thin, thick and elastic filaments
- thin filaments
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protein composition: actin, troponin and tropomyosin
functions: contains myosin head binding sites; slides along thick filament during contraction - thick filaments
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protein composition: myosin
functions: myosin heads (cross brideges) move thin filaments toward the center of sarcomere during contraction. - elastic filaments
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protein: titin/connectin
functions: anchors thick filaments to Z discs and stabilizes them during contraction and relaxation. - What is the function of the sarcoplasmic reticulum?
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During relaxation: stores Calcium ions
During contraction: releases calcium ions throuch Calcium ion release channels. - Explain the role of Calcium and regulator proteins in muscle contraction.
- An increase in calcium concentration in the sacoplasm starts filament sliding, while a decrease turns off the sliding process.