1. Anatomy & Physiology Ms. Cohen
The Muscular System
Anatomy & Physiology
Ms. Cohen

2. Do Now
At your table is a picture of a muscle that can be found in the body. Where do you think this muscle is found? Name 5 things your body can do using this muscle.

3. What are the functions of muscles?
Movement, posture, heat production

4. Where do you find muscle tissue?
Skeletal, smooth, cardiac

5. Muscle Histology
Striations
Branches

6. How does a muscle move? Motor Unit
muscles must be stimulated by nerve impulses (motor neuron)
Point of contact between nerve and muscle is a neuromuscular junction

7. Muscle Organization Myofilaments
The muscle can be broken into long bundles of proteins called muscle fibers.
These fibers are made up of fine, threadlike structures called myofilaments which contain two types of proteins: thick - myosin, and thin - actin

8. Sarcomere - functional contractile unit of a muscle fiber
The SARCOMERE is the functional contractile unit of the muscle fiber.
This is where all the “action” happens!
Striations

9. How does a muscle contract?

10. Video of muscle contraction

11. What is happening between the muscle proteins?
During contraction, the thick and thin myofilaments attach to form cross bridges
These bridges act as levers to ratchet filaments past each other
Calcium must be present for bridges to form
Any idea why rigor mortis sets in when people have died?

12. sarcomere

14. Sarcomere - functional contractile unit of muscle
Sarcolemma - cell membrane of skeletal muscle, receives nerve impulses
Sarcoplasmic reticulum - smooth ER in muscle cell. Stores calcium ions
Myofibrils - muscle fibers
Myofilaments - proteins that make up myofibrils
Actin - thin protein in muscle that makes contraction
Myosin - thick protein in muscle that makes contraction
Myoglobin - red pigment which binds to and stores oxygen in muscle cells.
Troponin - regulatory protein that turns contraction on
Tropomysin - regulatory protein that turns contraction off
Calcium - ion binds to troponin-tropomysin molecule, thus changing shape of molecule and turning contraction ON.