Intro to Muscular System

Question 1

Muscle is Latin for

Answer 1

“little mouse”

(myo- ; mys- ; sarco-)

Question 2

Approximately how many muscles are in the body?

Answer 2

700

Question 3

Muscle accounts for what percentage of total body weight?

Answer 3

40-50%

Question 4

Muscle Characteristics

Answer 4

1. Excitability
   
   1. responds to external stimuli (hormones/nervous stimulus)
2. Contractibility
   
   1. actively shortens along longitudinal axis
3. Extensibility
   
   1. can stretch beyond original length without tearing
4. Elasticity
   
   1. recoils to its original length

Question 5

Muscle Organ =

Answer 5

muscle fibers (cells) + connective tissue + nervous tissue + epithelial tissue

Question 6

Skeletal Muscle Function

Answer 6

Change chemical energy into mechanical energy

Question 7

Chemical Energy (Muscle)

Answer 7

The chemical energy for the cell is ATP

ATP → ADP + P_i + energy

Question 8

Mechanical Energy (Muscle)

Answer 8

1. Skeletal / Skin Movement
2. Controls Posture / Body Positions / Joints
3. Supports soft tissue
4. Regulation of incoming and outgoing material
5. Mantains Body Temperature

Question 9

Skeletal (Somatic) Muscle Characteristics

Answer 9

1. Striations (sarcomeres)
2. Cylindrical-fibers
3. Multiple, peripheral nuclei
4. Voluntary control
5. Cannot divide
6. Will fatigue over time
7. Attached to skeleton and skin

Question 10

Every muscle organ has…

Answer 10

1. at least one artery, one vein, and one nerve
   
   1. travel within CT to get to cells
   2. activate for contraction
   3. provide blood fro cells
2. Muscle fibers (cells)
3. Fascicles
   
   1. bundles of muscle cells
4. Connective tissue
   
   1. wraps the muscle organ into multiple “tubes within a tube within a tube”

Question 11

Innervation of Muscle cells

Answer 11

neuron connections to musccle cells

Question 12

Action Potential travels down motor neuron to the…

Answer 12

neuromuscular junction

Question 13

Neuromuscular Junction

Answer 13

The connection betwen the motor neuron’s syaptic knob and the sketetal muscle cell membrane’s motor end plate

Question 14

Motor end plate

Answer 14

portion of the muscle cell’s sarcolemma in contact with the axon terminals

Question 15

Neuron’s synatic knobs release…

Answer 15

Acetycholine (ACh)

Question 16

Motor unit

Answer 16

one motor neuron and all attached muscle fibers

Question 17

Formation of a tendon

Answer 17

Epimysium fibers blend with Perimysium fibers and Endomysium fibers

Question 18

Tendon

Answer 18

connect muscle to bone

Question 19

myosatellite cells

Answer 19

• myoblasts that sit in connective tissue between two connected muscle cells
• may be activated with exercise, disease, or damage
• may help with repair/regeneration of muscle cells

Question 20

Myofibril

Answer 20

complex organelle composed of bundles of myofilaments

Question 21

What you should know for the Sliding Filament Theory

Answer 21

1. myofilaments (contractile proteins) are located in bundles called myofibrils
2. Myofilaments = Actin + Myosin
3. ATP is the “fuel” that runs the contraction
   
   1. ATP → ADP + inorganic phosphate + energy
4. A sarcomere is the distance from one z-line to the next z-line
5. The sarcoplasmic reticulus (SR) of the cell stores and releases Ca²⁺
6. The sarcolemma has invaginations that extend towards the cell center called Transverse Tubules (T-tubules). The lay next to the SR