1. Muscle relationships and types of contractions
Muscle Physiology
Muscle relationships and types of contractions

2. Muscle Tissue Skeletal Muscle Cardiac Muscle Smooth Muscle
There are three types of muscle tissue in the body. Skeletal muscle is the type that attaches to our bones and is used for movement and maintaining posture. Cardiac muscle is only found in the heart. It pumps blood. Smooth muscle is found in organs of the body such as the GI tract. Smooth muscle in the GI tract moves food and its digested products.

3. Cardiac Muscle Branching cells One/two nuclei per cell Striated
Involuntary
Medium speed contractions
Cardiac muscle tissue is only found in the heart. *Cardiac cells are arranged in a branching pattern. * Only one or two nuclei are present each cardiac cell. *Like skeletal muscle, cardiac muscle is striated. *Cardiac muscle is involuntary. *Its speed of contraction is not as fast as skeletal, but faster than that of smooth muscle.

4. Smooth Muscle Fusiform cells One nucleus per cell Nonstriated
Involuntary
Slow, wave-like contractions
Smooth muscle is found in the walls of hollow organs. *Their muscle cells are fusiform in shape. *Smooth muscle cells have just on nucleus per cell. *Smooth muscle is nonstriated. *Smooth muscle is involuntary. *The contractions of smooth muscle are slow and wave-like.

5. Skeletal Muscle Long cylindrical cells Many nuclei per cell Striated
Voluntary
Rapid contractions
Skeletal muscle attaches to our skeleton. *The muscle cells a long and cylindrical. *Each muscle cell has many nuclei. *Skeletal muscle tissue is striated. It has tiny bands that run across the muscle cells. *Skeletal muscle is voluntary. We can move them when we want to. *Skeletal muscle is capable of rapid contractions. It is the most rapid of the muscle types.

6. Skeletal Muscle Produce movement Maintain posture & body position
Support Soft Tissues
Guard entrance / exits
Maintain body temperature
Store nutrient reserves

7. Skeletal Muscle Structure
Organization of Connective Tissues
Muscle attachments
Endomysium, perimysium, and epimysium come together at ends of muscles to form connective tissue attachment to bone matrix i.e., tendon (bundle) or aponeurosis (sheet)
Nerves
Skeletal muscles are voluntary muscles, controlled by nerves of the central nervous system (brain and spinal cord)
Blood Vessels
Muscles have extensive vascular systems that
1) Supply large amounts of oxygen
2) Supply nutrients
3) Carry away wastes
Skeletal Muscle fibers are:
Are very long
Develop through fusion of mesodermal cells (myoblasts)
Become very large
Contain hundreds of nuclei

8. Skeletal Muscle Fiber Internal Organization of Muscle Fibers
The sarcolemma
The cell membrane of a muscle fiber (cell)
Surrounds the sarcoplasm (cytoplasm of muscle fiber)
A change in transmembrane potential begins contractions
Transverse tubules (T tubules)
Transmit action potential through cell
Allow entire muscle fiber to contract simultaneously
Have same properties as sarcolemma
Myofibrils
Lengthwise subdivisions within muscle fiber
Made up of bundles of protein filaments (myofilaments)
Myofilaments are responsible for muscle contraction
Types of myofilaments:
thin filaments:
made of the protein actin
thick filaments:
made of the protein myosin
Sarcoplasmic reticulum (SR)
A membranous structure surrounding each myofibril
Helps transmit action potential to myofibril
Similar in structure to smooth endoplasmic reticulum
Forms chambers (terminal cisternae) attached to T tubules
Triad
Is formed by one T tubule and two terminal cisternae
Cisternae:
concentrate Ca2+ (via ion pumps)
release Ca2+ into sarcomeres to begin muscle contraction

9. Sarcomere Internal Organization of Muscle Fibers M Lines and Z Lines:
Sarcomeres
The contractile units of muscle
Structural units of myofibrils
Form visible patterns within myofibrils
Muscle striations
A striped or striated pattern within myofibrils:
alternating dark, thick filaments (A bands) and light, thin filaments (I bands)
M Lines and Z Lines:
M line:
the center of the A band
at midline of sarcomere
Z lines:
the centers of the I bands
at two ends of sarcomere
Zone of overlap:
the densest, darkest area on a light micrograph
where thick and thin filaments overlap
The H Band:
the area around the M line has thick filaments but no thin filaments
Titin:
Strands of protein
reach from tips of thick filaments to the Z line
stabilize the filaments

10. The Ca ions bind to the troponin
This binding weakens troponin-tropomoysin complex and actin
Troponin moiecule changes position, rolling the tropomyosin away from the active sites on actin
Thus allowing them to interact with energized myosin heads

11. With the active sites on the actin exposed, the myosin heads bind to the, forming cross-bridges

12. After cross-bridge formation, the ATP present in the myosin is used to “cock” (the opposite direction from its resting state). As the ATP is used and the ADP + P is released, the “power stroke” occurs as the myosin pivots toward the M line.

13. When another ATP molecule attaches to the myosin head, the cross-bridge between the active site of the actin molecule and myosin head is broken. Thus freeing up the head to make another bridge and complete the contraction.

14. Myosin splits the ATP into ADP + P and uses the released energy to re-cock the myosin head (reaching forward). Cycle can be repeated endlessly as along as calcium ion concentration remain high and sufficient ATP is present.
ATP produced in cells – aerobic vs. anaerobic
Ca controlled by what?

15. Muscle Relationships
Anonist – The muscle which the load/tension is going through.
Antagonist – The muscle which is relaxing through the movement.
Stabilisers – groups of muscles which hold the movement in place.

16. Muscle Contraction Types
Isotonic contraction – Concentric
- Eccentric
Isometric contraction

17. Muscle Contraction Types
Isotonic contraction
Isometric contraction
Two Types of Skeletal Muscle Tension
Isotonic Contraction
Skeletal muscle changes length:
resulting in motion
If muscle tension > load (resistance):
muscle shortens (concentric contraction)
If muscle tension < load (resistance):
muscle lengthens (eccentric contraction)

18. Muscle Contraction Types
Isotonic contraction
Isometric contraction
Two Types of Skeletal Muscle Tension
Isometric contraction
Skeletal muscle develops tension, but is prevented from changing length
Note: iso- = same, metric = measure
Produces no movement
Used in
Standing
Sitting
Posture