1. Anatomy and Physiology L2/L3
Muscle Anatomy
Anatomy and Physiology L2/L3

2. Lets Review!! What type of muscle tissue does each describe?
Voluntary
Contractions are slow and steady
Walls of visceral organs & blood vessels
Contract rapidly & vigorously
Long, thin & multinucleated
Striated
Involuntary
Contracts rhythmically
Found in cardiac tissue

3. Functions of skeletal muscle
Movement: of skeleton by use of muscles acting in pairs or groups
Posture Maintenance: keeping upright
Heat generation: product of movement. Serves to maintain norm. body temp (homeostasis)

4. Gross Anatomy of skeletal muscle
muscle cell aka (fiber): made up of many myofibrils
Epimysium (deep fascia: outer, toughest covering of Dense connective tissue
Fascicles/fasciculus :name given to bundles of muscle fibers/cells

5. Anatomy of skeletal muscle

6. Anatomy of skeletal muscle (cont)
Myofibril: many make up a cell/fiber
Sarcolemma
(plasma membrane): it is the cell membrane surrounding cell/fiber
SR: similar to ER
Sarcomere: contractile units making up myofibrils containing actin &myosin.
-Multi-nucleated

7. Myofibril: many sarcomeres make up the myofibrils
Thread-like protein structures
2 types:
Thick– Myosin
Thin – Actin
Alternating light/dark create striations
Allow muscle to contract (shorten) and relax (lengthen)

9. Contaction and Relaxation of Skeletal Muscle fiber

10. Chemical Part of Muscle Contraction: Motor Unit: Composed of motor neuron & all the muscle fibers
NM Jxn
Terminal end stores ACh
ACh released into fiber
ACh acts as stimulus

11. Steps in Muscle Contraction
Nerve impulse travels down motor neuron to NM junction
Acetylcholine (ACh) released into muscle
ACh diffuses across muscle fiber
Signals the SR to release stored Calcium
Ca initiates formation of cross bridges between Actin and Myosin
*Ca stimulates a change in actin shape
6. sacrcomeres shorten and muscle fibers contract

13. Steps in Muscle Relaxation
Motor neuron impulse to stop contraction so Ach is inactivated.
Ca moves (Active transport) back into SR (to be stored) (*ATP)
Absence of Ca causes crossbridges to break because actin changes back its shape (*ATP)
Actin filaments slide back
RESULT: Muscle relaxes

16. Homework: #1and #2
#1 Based on knowledge of muscle physiology; what steps must or do not occur in the condition Rigor Mortis at the chemical level and what happens to the body?
#2. What causes Botulism?and how might we (humans) come in contact with the toxin?
What physiological/chemical effects can Botulism have? What treatments?

17. Homework: #3 and #4 #3. Look up compartment syndrome
Cause: what happens at the chemical level?
symptoms
Treatment
#4. Look up multiple sclerosis
Be able to discuss:
Cause; and what happens at the chemical level?
treatment

18. Homework: #5 Muscular Dystrophy
Protein structure of muscle is mainly Actin & Myosin.
What is the function of dystrophin?
Muscular Dystrophy?
Cause: at the chemical level?
Types?
Physiological effects on body

19. Take a Break and Review! Go to following animation
Great animations and review activities!

20. Quick Quiz: 18 pts (3 each)
1. Describe each: epimysium, fascicles, fiber/cell, sarcoplasm
2. Explain where the sarcomere is and what is has to do with muscle contraction
3. What has to happen in order for a body part to move?

21. Quiz cont. 4. What happens at the neuromuscular junction?
5. Explain steps in muscle contraction
6. Explain steps in muscle relaxation