Tendons & Muscles- muscles contract and tendons prevent movement
Articular Surface Contour- shape of atricular surface
Which type of joint in the body allows the greatest range of motion?
The joint of the body tend to follow a pattern of increased strength causing less motion at the joint. Which of the following joints are the strongest:
-The pubis symphysis
-The articulation between the frontal bone and a parietal bone
The articulation between a frontal and a parietal bone
What is an Ellipsoidal joint?
(Condylar Joint)An oval articular surface nestles within a depression on the opposing surface. ex.connect the fingers/toes to meta-carpal/tarsals
What are Plane Joints?
(Gliding) the relatively flat articular surfaces slide across one another, but the amount of movement is very slight. ex. between carpal/tarsal bones
What are Hinge Joints?
Permit angular movement in a single plane; like opening/closing a door. (monaxial) ex. elbow
What is a Pivot Joint?
(monaxial) permit only rotation. ex. between the atlas/axis
What is a Saddle Joint?
Resembles a saddle because it's concave on one end and convex on the other. Extremely Mobile.(biaxial) ex. twiddling your thumbs
What is a Ball-and-socket joint?
The round head of a bone rests in the cup-shaped depression in another. (Triaxial) ex. Shoulder/Hip
What does a Glenoid Labrum do?
Enlarges the joint cavity
Which of the following ligaments is partially or completely dislocated during a shoulder separation?
What statement correctly describes the shoulder joint?
Articular cartilage covers the head of the humerus and the glenoid cavity.
What contributes the most to the stabilization of a shoulder joint?
Rotator Cuff muscles
Ligaments & muscles that move the humerus
The function of a bursa is to
Reduce friction between a bone & tendon
Smooth the surface outline of a joint
What are the 3 main functions of the Muscular System?
1. Produce Macroscopic movements
2. Produce Forces that Prevent movement
3. Produce Heat
What are the 3 types of Muscle Tissue?
What are common properties associated with the Muscular System?
Cells are elongated into "fibers"
Plasma membranes are electrically 'excited'
Muscle fibers produce Contractile Force
Muscle fibers are extensible & elastic
How are muscles and connective tissues "blended" in skeletal muscles?
Skeletal Muscle (Organ)
Muscle Fascicle (Bundle of cells)
Muscle Fiber (Cell)
How to Muscle Fibers develope?
1.Through the fusion of Myoblasts
2. Myosatellite cells bind to the immature muscle fiber which is surrounded my numerous nuclei
What is the function of the Myosin head?
it acts as a motor that pulls the Z line in to shorten the sarcomere by 'sliding' between thick and thin filaments
What is the Z line made of?
What is the H band?
The area of non-overlap between thick and thin filaments
What happens as the Z line gets closer to the the A band?
The overlap shrinks
What keeps the Z line centered?
what is the role of Titin filamants?
Titin anchors thick filaments to the Z line (Stretch the sarcomere- strectch titin = Resistance)
What happens when the zone of overlap is reduced to zero?
Thick/thin filaments cannot interact at all
Muscle fibers cannot produce any active tension
Contraction cannot occur
What happens if you increase the sarcomere length?
Reduces the size of the zone of overlap
Reduces the number of potential cross-bridge interactions
What happens in the Optimal Resting range?
Produce Greatest tension/force
Maximum number of cross-bridges can form
What happens in a decrease in sarcomere length?
Sarcomeres cannot shorten much more
Thin filaments meet at the M line and overlap the thin filaments on the other side
Still produce 100% force
What happens when the resting sarcomere is as short as it can be?
Tension production falls to zero
Thick filaments are jammed against the Z line (they overlap too much)
Sarcomere cannot shorten anymore
Interferance with cross-bridges
Don't want to be here (Delta State)-disruptive & breaks down
What is the cross-bridge cycle?
A series of molecular events that occur after the excitation of the sarcolemma.
What is a Cross-bridge?
A Myosin head bound to Actin
What structure is the functional unit of contraction in skeletal muscle fiber?
Calcium ions couple excitation of a skeletal muscle fiber to contraction of the fiber. Where are calcium ions stored within the fiber?
The Sarcoplasmic Reticulum
After a power stroke, the myosin head must detach from actin before another power stroke can occur. What causes cross bridge detachment?
ATP binds to the myosin head
How does the myosin head obtain the energy required for activation?
Hydrolysis of ATP
What specific event triggers the uncovering of the myosin binding site on actin?
Calcium ions bind to troponin and change its shape
When does cross bridge cycling end?
Cross bridge cycling ends when sufficient calcium has been actively transported back into the sarcoplasmic reticulum to allow calcium to unbind from troponin.
How is Contraction regulated?
Binding sites are covered by Tropomyosin to keep from contracting
To turn ON-Put Calcium ions in and bind to Troponin (this causes a change in the shape and rolls Tropomyosin out of the way to make it capable of turning ON)
To turn OFF- Take away the Calcium ions and Tropomyosin rolls back in and keeps from forming cross-bridges
Explain Excitation-Contraction Coupling.
Excitation- A signal from the nervous system travels to every sarcomere simultaniously
Starts the signal at the Sarcolemma and spread rapidily
Signal comes from the Sarcolemma to the inside of the cell by Transverse tubules (T tubules)
then travels through the Terminal cisternae to the triad and transmits an action potential to the rest of the cell and gets transduced into another signal
The Sarcoplasmic reticulum is jammed full of calcium and the signal flows out creating a "Twitch"
How do you initiate muscle contraction "Twitch"?
1. Action Potential reaches T tubule
2. SR releases Calcium
3. Active-site exposure, cross-bridge formation
4. Contraction begins
How do you achieve muscle relaxation?
1. SR recaptures Calcium ions
2. Active sites covered, No cross-bridge interactions
3. Contraction Ends
4. Relaxation occurs, Passive return to resting length
True or False?
All skeletal muscle fibers produce "twitches"?
True; But the amount of time it takes to produce "twitches" varies.
What are Slow fibers?
Smaller in diameter
Darker color due to Myoglobin
What are Fast fibers?
Larger in diameter
Paler in color
Easily Fatigued (Shorten more rapid and contract faster)
*Larger Diameter = More Force Produced*
What are Parallel Muscles?
Fascicles are parallel to longitudinal axis. (ex. Biceps)