Muscular System (EXAM #2)

Question 1

What is the overview of Muscular System?

Answer 1

• Refers to skeletal muscle system
• Primarily attached to bone
• Produce movement by contracting

Question 2

What is Skeletal Muscle?

Answer 2

• Cells called fibers
• Fascicle = group fibers
• Whole Muscle = group of fascicles

Question 3

What are the 2 CT Components of Skeletal Muscle?

Answer 3

1. Fascia (connective tissue surrounding muscles or other organs)
2. Tendons and Aponeuroses

Question 4

Fascia (connective tissue surrounding muscles or other organs)

Answer 4

• Epimysium
  
  • Surrounds entire skeletal muscle
• Perimysium
  
  • Surrounds fascicles within skeletal muscle
• Endomysium
  
  • Surrounds each muscle fiber (cell) within skeletal muscle

Question 5

Tendons and Aponeuroses

Answer 5

• Extensions of epimysium, perimysium, and endomysium
• Anchors muscle to bone (periosteum), cartilage, fascia

Question 6

Tendon

Answer 6

• A rope-like bundle of dense regular connective tissue
  
  • e.g. calcaneal (achilles) tendon

Question 7

Aponeurosis

Answer 7

• A flat sheet of dense regular connective tissue
  
  • e.g. epicranial aponeurosis (scalp)

Question 8

What is the Skeletal Muscle Fiber Structure?

Answer 8

Large cylindrical and multinucleate cells

Question 9

What are the Parts of Skeletal Muscle Fiber Structure?

Answer 9

1. Sarcolemma
2. T-tubules
3. Sarcoplasm
4. Myofibrils
5. Sarcoplasmic Reticulum

Question 10

Sarcolemma

Answer 10

Cell Membrane

Question 11

T-tubules

Answer 11

Continuations of sarcolemma that extend deep into fiber (cell)

Question 12

Sarcoplasm

Answer 12

Cytoplasm

Question 13

Myofibrils

Answer 13

• Intracellular Structures
• Within each fibre tthere are several hundreds to thousands
• Composed of Sarcomeres

Question 14

What are the structures of sarcomere?

Answer 14

• Made of 2 types of myofilaments
• The myofilaments create dark and light bands (striations) of the sarcomere
• Banding Pattern
• Sarcomeres join end to end (at Z discs) to form a myofibril

Question 15

What are the 2 types of Myofilaments

Answer 15

1. Thin Myofilaments
2. Thick Myofilaments

Question 16

Thin Myofilaments

Answer 16

• Formed by 3 proteins involved in contraction:
  
  • Actin
  • Tropomyosin
  • Troponin

Question 17

Thick Myofilaments

Answer 17

• Formed by a protein called myosin
• Attached to z discs by titin
• Myosin has rod-like tail with 2 globular heads
  
  • At rest, the heads extend toward actin and during contraction attaches to actin to shorten the sarcomere

Question 18

Whar are parts of the banding pattern?

Answer 18

1. A band
2. H zone
3. I band
4. Z discs (in center of I band)
5. M line

Question 19

A Band

Answer 19

Dark band that is length of thick myofilaments

Question 20

H Zone

Answer 20

Lighter area at center of A band

Question 21

I Band

Answer 21

Light band consisting of thin myofilaments

Question 22

Z Discs

Answer 22

• Connected to thick myofilaments (via titin) and thin myofilaments
• Connection point between adjacent sarcomeres

Question 23

M Line

Answer 23

WHere myosin tails (thick myofilaments) attach to each other (center of sarcomere)

Question 24

Sarcoplasmic Reticulum

Answer 24

• Is smooth endoplasmic reticulum
• Triad is a formed from 2 enlarged areas of sarcoplasmic reticulum (terminal cisternae), and a T-tubule that runs in between them

Question 25

What are the 3 Ways Muscles Produce Movement?

Answer 25

1. Lever System 2. Pulling on bones when they contract 3. Using group action

Question 26

Lever System

Answer 26

- Bone/muscle interaction at a joint - Parts: - Levers = Bone - Fulcrum = Joint - Effort = Contraction of agonist - Resistance = opposes movement - Effort must be greater than resistance to get movement

Question 27

Pulling on bones when they contract

Answer 27

- Origin - Attachment of tendon to stationary bone - Insertion - Attachment of tendon to movable bone

Question 28

Using group action

Answer 28

- Agonist - Major muscle producing the movement - Synergists - Help the agonist action and prevent undesirable motions caused by the agonist - Antagonist - Produces opposite action of agonist (contraction inhibited when agonist contracts)

Question 29

Flexion of Forearm (Example #1)

Answer 29

- Agonist = Biceps brachii - Antagonist = Triceps brachii - Synergists = Brachialis, Brachioradialis - Lever = Radius (insertion of agonist) - Fulcrum = Elbow joint - Effort = Muscle contraction - Resistance = Weight of object plus forearm

Question 30

Extension of Forearm (Example #2)

Answer 30

- Agonist = Triceps brachii - Antagonist = Biceps brachii