Muscle and Skeletal System

Question 1

Cartilage

Answer 1

-Connective tissue

Question 2

What synthesizes cartilage?

Answer 2

Chondrocytes

Question 3

Bone

Answer 3

• Specialized mineralized connective tissue

- Elastic, lightweight

Question 4

Compact bone

Answer 4

• Dense bone deposited in units called osteons

- Channels called Haversian canals surrounded by bony matrix (lamellae)

Question 5

Spongy bone

Answer 5

• Much less dense

- Interconnecting spicules with yellow marrow (adipose) or red marrow (blood formation)

Question 6

Osteoblasts

Answer 6

• Synthesize/secrete organic components of bone matrix - collagen
• Mature into osteocytes

Question 7

Osteoclasts

Answer 7

• Lg, multinucleated cells

- Bone reabsorption

Question 8

What are the methods of bone formation?

Answer 8

• Endochronal Ossification (cartilage)

- Intramembranous ossification (mesenchymal tissue)

Question 9

Pyramidal system

Answer 9

Axons of pyramidal cells of motor cortex synapse on lower motor neurons

Question 10

What is the extrapyramidal system?

Answer 10

• Somatic motor commands at the involuntary level

- Skeletal muscle tone primarily controlled by red nucleus in midbrain

Question 11

Skeletal muscle

Answer 11

• Mulitnucleated, striated
• Controlled by SNS, voluntary movements
• Myofibrils (divided into sacromeres) enveloped in sarcoplasmic reticulum
• High energy requirements –> mitochondria rich

Question 12

T system

Answer 12

• Transverse tubules perpendicular to myofibrils

- Ion channels –> propagate action potentials

Question 13

Which bands reduce in size during muscle contraction?

Answer 13

-I and H band

Question 14

What is the neuromuscular junction?

Answer 14

-Link between nerve terminal and sarcolemma of muscle fiber

Question 15

How is an action potential generated in muscle contraction?

Answer 15

-Enough neurotransmitters diffuse across cleft and stimulate receptors on sarcolemma, changing permeability

Question 16

What occurs once an action potential is generated?

Answer 16

• Potential is conducted along sarcolemma and T system into interior of muscle fiber
• SR release Ca++ into sarcoplasm –> bind troponin C on actin –> actin/myosin slide –> sarcomere contracts

Question 17

What is rigor mortis?

Answer 17

-Muscle contract w/o potentials due to lack of ATP which is needed to release myosin heads from actin filaments

Question 18

Isotonic contraction

Answer 18

• Muscle shortens against fixed load

- Constant tension

Question 19

Dynamic contraction

Answer 19

• Concentric and eccentric contractions

- Change length of muscle and tension

Question 20

Concentric contraction

Answer 20

-Muscle fibers shorten, tension increases

Question 21

Eccentric contraction

Answer 21

-Muscle fibers lengthen, tension increases

Question 22

Isometric contraction

Answer 22

• Both ends of muscles are fixed, no change in length

- Tension increases

Question 23

How can strength of muscle contraction be increased?

Answer 23

• All or nothing response

- Increase by recruiting more muscle fibers

Question 24

Simple twitch

Answer 24

• Single muscle fiber to brief stimulus

- Latent, contraction, relaxation

Question 25

Temporal summation

Answer 25

-Contractions combine --> stronger/prolonged

Question 26

Tetanus

Answer 26

- Muscle fibers continuously stimulated and can't relax | - Muscle will fatigue and contraction weakens

Question 27

Tonus

Answer 27

- Partial contraction | - Muscles are never completely relaxed

Question 28

Cori cycle

Answer 28

- Converts lactic acid in liver to glucose --> bloodstream - Muscle uses glucose or stores as glycogen - NOT include breaking down glycogen/production of lactic acid

Question 29

Smooth muscle

Answer 29

- Digestive tract, bladder, uterus, blood vessel walls - One central nucleus - No striations - Smooth, continuous contractions

Question 30

Cardiac muscle

Answer 30

- Actin/myosin arranged in sarcomeres (striated) | - Only 1-2 nuclei

Question 31

What are forms of energy reserves for muscles?

Answer 31

- Creatine phosphate | - Myoglobin (store oxygen)

Question 32

What do the inorganic components of bone form?

Answer 32

-Hydroxyapatite crystals (phosphate, calcium, hydroxide)

Question 33

Which bones are typically formed from endochondral ossification?

Answer 33

-Long bones

Question 34

Which bones are typically formed by intramembranous ossification?

Answer 34

-Skull

Question 35

What makes up the diaphysis?

Answer 35

-Bone marrow surrounded by compact bone

Question 36

What makes up the epiphysis?

Answer 36

-Spongy bone coated with thin layer of compact bone

Question 37

What is the epiphyseal plate?

Answer 37

- Separate the diaphysis and epiphsis - Cartilage in growing bones - Source of longitudinal growth

Question 38

Why are muscles found in antagonistic pairs?

Answer 38

- Because extension can only occur passively | - E.g. triceps and biceps