Muscular System 1 Flashcards
Describe the form & function of skeletal muscle?
Attached to bone or skin – single long multinucleate with striations
Describe the form & function of cardiac muscle?
Walls of the heart – branched chain bi-uninucleate with striations
Describe the form & function of smooth muscle?
Muscle wall of hollow visceral organs – single fusiform uninucleate
What are 4 Characteristics of Muscle?
Excitability, Contractility, Extensibility & Elasticity
What is extensibility?
The ability to stretch
What is elasticity?
The ability to recoil
What are 5 Functions of muscle?
Aid movement, generate heat, maintain body posture, regulate visceral organ size, and move substances throughout body
How do muscles move?
By pressuring force on tendons which pull on other structures such as bone or skin
Where are skeletal muscles attached?
Across articulating bones that form joints
What two functions connect muscle to bone?
Origins & insertions
What happens during muscle movement?
One end is connected to the origin of the muscle that remains stationary, and the other end is connected to a tendon that contracts or moves called its insertion
What is the gaster?
The fleshy part or middle of a muscle that contracts
Why do muscular movements occur?
Due to several muscular movements
How are muscles grouped?
Opposing (antagonistic) pairs
What are agonists?
The prime movers which bring about contraction
What are antagonists?
Muscles that oppose movement & relax
What are synergist muscles?
Prevent unwanted movement
What is a fixator muscle?
Hold the origin in place
What is the Sarcoplasmic reticulum
Similar to smooth ER
What is the Sarcoplasm?
Similar to cytoplasm
What is the Sarcolemma
Muscle membrane
What is the basic structure of muscle?
Tube within progressively smaller & smaller tubes
What are muscles made of?
Bundles of muscle fibers called fascicles
What is the Epimysium?
Most outer covering of muscle that surrounds the entire muscle
Where is the Fascicle?
Within the epimysium and contain small bundles of muscle within a tube
What is the Perimysium?
What is the Perimysium?
Covers each fascicle
What is the Endomysium?
Covers individual muscle bundles in each fascicle
What are myofibrils?
Bundles of muscle fibers in each fascicle bundle
What are the three exceptional structures in muscle fibers?
Myofibrils, sarcoplasmic reticulum and T-tubules
Describe myofibrils?
Densely packed rod-like organelles surrounded by sarcolemma and covered by striations of protein which enable muscle contractions
What are sarcomeres?
The smallest contractile units of muscle fibers located on myofibrils
Describe the structure of sarcomeres.
Run from one Z-disc to another which are their boundaries in the thousands on myofibrils
Describe the function of sarcomeres?
Contractions of sarcomeres enable muscle contractions
What are striations?
Alternating lines produced by the thin, and thick protein microfilaments surrounding the sarcomere
What are Myosins?
Thick filaments that contain a tail heads, called myosin heads which attach to thin filaments to form cross–bridges
What is the function of cross-bridges?
The cross-bridge formation enables the myosin and actin to glide past each other during relaxation and contraction, contracting the sarcomeres
What is actin?
Thin filaments that form structures called tropomyosin, that are topped with actin which contain myosin-binding sites that are blocked by the tropomyosin
What is the function of troponin?
Controls tropomyosin and if stimulated unlock tropomyosin from their place exposing the myosin-binding for the myosin
What is the function of calcium in muscle contractions?
Calcium binds onto the troponin which directs the movement of tropomyosin away from the actin, and exposing the myosin-binding sites
What is the Sliding-Filament Mechanism?
The myosin forces the actin towards the center of the sarcomeres, through a series of broken and formed cross bridges known as the Ratchet Mechanism and decreasing the distance between z-discs and shortening the sarcomere and producing muscle contractions.
