Muscoskeletal System

Question 1

Types of muscles

Answer 1

1. Skeletal muscle
2. Smooth muscle
3. Cardiac muscle

Question 2

Skeletal muscle functions

Answer 2

1. Support body
2. Allow movement
3. Compress venous structures to propel blood and lymph
4. Shivering

Question 3

Skeletal muscle features

Answer 3

1. Striated due to sarcomeres
2. Multinucleated
3. Has red and white fibers

Question 4

Red fibers

Answer 4

Slow-twitch.

1. High myoglobin content (aerobic)
2. Mostly in muscles that contract slowly but sustain activity

Question 5

White fibers

Answer 5

Fast-twitch.

1. Less myoglobin, so lighter in color
2. Less mitochondria, rely more on glycolysis
3. Mostly in muscles that contract fast, but fatigues easily

Question 6

Smooth muscle functions

Answer 6

1. Involuntary movement

2. Regulation of BP

Question 7

Smooth muscle features

Answer 7

1. Single nucleus in center of cell
2. Contain actin and myosin, but not well-organized
3. Capable of more sustained contractions

Question 8

Tonus

Answer 8

Constant state of low-level contraction

Question 9

Myogenic activity

Answer 9

Contraction of smooth or cardiac muscle without nervous system input.

Question 10

Cardiac muscle features

Answer 10

1. Primarily uninucleated, but many do contain 2
2. Involuntary, but appears striated
3. Connected by intercalated discs that have many gap junctions
4. Relies on calcium for contraction

Question 11

Sarcomere

Answer 11

Thick and thin filaments

1. Z-line
2. M-line
3. I-band
4. H-zone
5. A-band

Question 12

During contraction, what lines decrease and what stays constant

Answer 12

1. H-zone, I-band, distance between Z-lines, and distance between M-lines become smaller
2. A-band size remains constant

Question 13

Myofibrils

Answer 13

Back-to-back sarcomeres attached to one another

Question 14

Sarcoplasmic reticulum

Answer 14

Modified ER that has a high calcium concentration that surrounds myofibrils

Question 15

Sarcoplasm

Answer 15

Modified cytoplasm of myocyte

Question 16

Sarcolemma

Answer 16

Cell membrane. Can propagate action potential using transverse (T) tubules

Question 17

Myocyte

Answer 17

contains many myofibrils arranged in parallel (muscle fibers). Numerous nuclei

Question 18

Muscle

Answer 18

Many myocytes in parallel

Question 19

Muscle contraction

Answer 19

1. Start: neuromuscular junction, nervous system communicate via efferent neurons
2. Travel down neuron until nerve terminal, ACh released into synapse
3. Depolarization down sarcolemma to T-tubules
4. When action potential reaches SR, Ca released
   , which binds to troponin triggering changes in tropomyosin.
5. Free globular heads of myosin binds to exposed sites on actin
6. Relaxation by ACh degradation

Question 20

Role of ATP in muscle contraction

Answer 20

1. Myosin carrying ADP + Pi bound to myosin-binding site after calcium trigger in tropomyosin structure
2. ATP binds to myosin head, the hydrolysis into ADP releases myosin from actin

Question 21

Skeletal structure

Answer 21

1. Axial: basic central framework - skull, vertebral column, ribcage, hyoid bone
2. Appendcular skeleton: limbs, pectoral girdle, pelvis

Question 22

Hyoid bone

Answer 22

In anterior neck, used for swallowing

Question 23

Bone composition

Answer 23

1. Compact bone: dense and strong

2. Spongy (cancellous) bone: spongy

Question 24

Spongy bones

Answer 24

1. Trabeculae: bony spicules (points)
2. Bone marrow: fills cavities between trabeculae
3. Long bones

Question 25

Bone marrow types

Answer 25

1. Red marrow: filled with hematopoietic stem cells | 2. Yellow marrow: fat and relatively inactive

Question 26

Long bones

Answer 26

1. cylindrical shafts (diaphyses), then metaphysis, end with epiphysis 2. Outer part: compact, inner part : spongy

Question 27

Periosteum

Answer 27

Fibrous sheath that surrounds long bone to protect it and serve as site of muscle attachment. Need to be healthy for bone marrow

Question 28

Tendons vs. Ligaments

Answer 28

1. Tendons: muscle to bone | 2. Ligaments: bone to bone

Question 29

Review microscopic bone structure

Answer 29

Harvesian canal, lacunae and osteocyte, cannaculi, periosteum, volkmann's canal, ostean

Question 30

Bone matrix: organic components

Answer 30

1. Collagen 2. Glycoproteins 3. Other peptides

Question 31

Bone matrix: inorganic components

Answer 31

They harden together to form hydroxypatite crystals 1. Calcium 2. Phosphate 3. Hydroxide ions

Question 32

Osteons/haversian systems

Answer 32

Structures of bony matrix of organic and inorganic components.

Question 33

Lacunae

Answer 33

House osteocytes

Question 34

Canaliculi

Answer 34

Allow exchange of nutrients and wastes between osteocytes, Haversian, and Volkmann's canals

Question 35

Osteoclasts

Answer 35

1. Macrophages of bone that reabsorb it. | 2. Polynucleated

Question 36

Chondrin

Answer 36

elastic, firm matrix

Question 37

Cartilage

Answer 37

1. Softer, more flexible than bone | 2. Avascular (no blood and lymphatic vessels), not innervated

Question 38

Endochondral ossification

Answer 38

hardening of cartilage into bone

Question 39

Intramembraneous ossification

Answer 39

Undifferentiated mesenchymal tissue transformed into bone. In bones of skull

Question 40

Mesenchymal tissue

Answer 40

embryonic connective tissue

Question 41

Synovial capsule

Answer 41

enclose joint cavity (arituclar cavity)

Question 42

Synovium

Answer 42

layer of soft tissue, secrete synovial fluid that lubricate movement in joints

Question 43

Articular cartilage

Answer 43

Coats articular surfaces of the bone so that impact is restricted to lubricated joint cartilage