Muscular and Skeletal Systems

Question 1

Skeletal system

Answer 1

Endoskeleton serves as the framework

Provides protection by surrounding delicate internal organs

Question 2

Cartilage

Answer 2

Connective tissue that is softer and more flexible than bone

Retained in places where firmness and flexibility are needed

Question 3

Chrondrocytes

Answer 3

Cells that synthesize cartilage

Question 4

Bone

Answer 4

Specialized mineralized connective tissue that withstands physical stress
Hard and strong while somewhat elastic and lightweight
Compact and spongy

Question 5

Compact bone

Answer 5

Dense bone that does not appear to have any cavities when observed with the naked eye
Matrix deposited in osteons

Question 6

Osteons

Answer 6

Haversian systems
Structural units of boney matrix
Consists of central microscopic Haversian canal surrounded by concentric circles of bony matrix (calcium phosphate) lamellae

Question 7

Spongy bone

Answer 7

Less dense
Interconnecting lattice of bony spicules (trabeculae)
Cavities between spicules are filled with yellow or red bone marrow

Question 8

Yellow marrow

Answer 8

Inactive

Infiltrated by adipose tissue

Question 9

Red marrow

Answer 9

Involved in blood cell formation

Question 10

Osteoblasts

Answer 10

Synthesize and secrete organic constituents of the bone matrix
Once surrounded by their matrix, they mature into osteocytes

Question 11

Osteoclasts

Answer 11

Large, multinucleated cells involved in bone reabsorption where bone is broken down and minerals are released into the blood

Question 12

Endochondral ossification

Answer 12

Existing cartilage is replaced by bone

Question 13

Intramembranous ossification

Answer 13

Mesenchymal (embryonic or undifferentiated) connective tissue is transformed into and replaced by bone

Question 14

Bone formation

Answer 14

Endochondral

Intramembranous

Question 15

Axial skeleton

Answer 15

The basic framework of the body

Skull, vertebral column, rib cage

Question 16

Appendicular skeleton

Answer 16

The bones of the appendage and the pectoral and pelvic girdles

Question 17

Ligaments

Answer 17

Attach bone to bone

Question 18

Tendons

Answer 18

Attach skeletal muscle to bones

Question 19

Origin

Answer 19

The point of attachment of a muscle to a stationary bone

Proximal end in limb muscles

Question 20

Insertion

Answer 20

The point of attachment of a muscle to a bone that moves

Distal end in limb muscles

Question 21

Extension

Answer 21

The straightening of a joint

Question 22

Flexion

Answer 22

The bending of a joint

Question 23

Muscle tissue

Answer 23

Bundles of specialized contractile fibers held together by connective tissue
Skeletal, smooth, and cardiac

Question 24

Pyramidal system

Answer 24

Provide rapid commands to the skeletal muscles and organs
Nervous control involving the axons of the pyramidal cells of the motor cortex, descending from the brain to synapse on lower motor neurons in the brain stem and spina cord

Question 25

Extrapyramidal system

Answer 25

Red nucleus in the mesencephalon is primarily control of skeletal muscle tone Issue somatic motor command at the unconscious, involuntary level

Question 26

Skeleton muscle

Answer 26

Responsible for voluntary movements Innervated by the somatic nervous system Fibers of multinucleated cells created by the fusion of several mononucleated embryonic cells

Question 27

Myofibril

Answer 27

Filaments embedded in skeleton muscle fibers | Divided into sacromeres

Question 28

Sacroplasmic reticulum

Answer 28

Envelopes myofibrils by a modified endoplasmic reticulum that stores calcium ions

Question 29

Sarcolemma

Answer 29

The cell membrane of muscle fibers Capable of propagating an action potential Connected to a T system oriented perpendicularly to the myofibrils

Question 30

T system

Answer 30

Transverse tubules Provide channels for ion flow throughout the muscle fiber Can propagate an action potential Perpendicular to myofibrils

Question 31

Striated muscle

Answer 31

Striations of light and dark bands

Question 32

Sacromere

Answer 32

Contractile units composed of thin (actin) and thick (myosin) filaments

Question 33

Z line

Answer 33

Define the boundaries of a single sarcomere Anchor the thin filaments Move toward each other during contraction

Question 34

M line

Answer 34

Runs down the center of the sarcomete

Question 35

I band

Answer 35

The region containing only thin filaments

Question 36

H zone

Answer 36

The region containing only thick filaments

Question 37

A band

Answer 37

Spans the entire length of the thick filaments and any overlapping thin filaments

Question 38

Contraction

Answer 38

Stimulated by message from the somatic nervous system sent via a motor neuron Receptors stimulated on the sarcolemma to generate an action potential. Conducted along the sarcolemma and T system and into the interior of the muscle fiber Sarcoplasmic reticulum releases calcium ions into the sarcoplasm which binds tropinin C on actin filaments Allosteric changes allow myosin heads to bind these site on actin ATP allows power stroke to pull Z bands closer together causing actin and myosin to slide past each other

Question 39

Types of muscle contractions

Answer 39

``` Isotonic Dynamic Concentric Eccentric Isometric ```

Question 40

Isotonic contraction

Answer 40

When a muscle shortens against a fixed load while the tension on that muscle remains constant

Question 41

Dynamic contraction

Answer 41

Concentric and eccentric | Results in a change in length of the muscle with a corresponding change in tension on that muscle

Question 42

Concentric contraction

Answer 42

The muscle fibers shorten and the tension on the muscle increases

Question 43

Eccentric contraction

Answer 43

The muscle fiber lengthens and the tension on the muscle increases

Question 44

Isometric contraction

Answer 44

When both ends of the muscle are fixed and no change in length occurs but the tension increases

Question 45

Simple twitch

Answer 45

The response of a single muscle fiber to a brief stimulus at or above the threshold stimulus Consists of a latent period, contraction period, and relaxation period

Question 46

Latent period

Answer 46

The time between stimulation and the onset of contraction | The action potential spreads along the sarcolemma and Ca2+ ions are released

Question 47

Relaxation period

Answer 47

The muscle is unresponsive to a stimulus | Absolute refractory period

Question 48

Temporal stimulation

Answer 48

When muscle fibers are exposed to very frequent stimuli and cannot fully relax Contractions combine, becoming stronger and more prolonged Tetanus

Question 49

Tonus

Answer 49

Muscles never completely relax and maintain partially contracted state at all times

Question 50

Cori cycle

Answer 50

During periods of strenuous activity, convert lactic acid in the liver to glucose for discharge into the bloodstream for energy or rebuild glycogen reserves

Question 51

Smooth muscle

Answer 51

Responsible for involuntary actions Innervated by the autonomic nervous system Smooth, continuous contractions Found in the digestive tract, bladder, uterus, and blood vessel walls Central nucleus and not striated

Question 52

Cardiac muscle

Answer 52

Characteristics of skeletal and smooth muscle Strong, forceful contractions Actin and myosin filaments arranged in sarcomeres giving striated appearance Only one or two central nuclei

Question 53

Creatine phosphate

Answer 53

Temporary store of high-energy compound

Question 54

Myoglobin

Answer 54

Haemoglobin-like protein found in muscle tissue | High oxygen affinity to maintain oxygen supply in muscles