Chapter 1: Structure and Function of Body Systems

Question 1

Describe the axial skeleton.

Answer 1

Skull (cranium)
Vertebral column (C1 through coccyx)
Sternum
Rib cage

Question 2

Describe the appendicular skeleton.

Answer 2

Shoulder (pectoral girdle): scapulae, clavicles
Arm and wrist bones: humerus, radius, ulna, carpals, metacarpals, phalanges
Pelvic girdle (coxal or innominate bones)
Leg and ankle bones: femur, patella, fibula, tibia, tarsals, metatarsals, phalanges

Question 3

Joints

Answer 3

Articulations between bones

Question 4

Fibrous joints

Answer 4

Joints that allow no movement (e.g. sutures of the skull)

Question 5

Cartilaginous joints

Answer 5

Joints that allow for limited movement (e.g. intervertebral disks)

Question 6

Synovial joints

Answer 6

Joints that allow for considerable movement (e.g. elbow, knee)

Question 7

Hyaline cartilage

Answer 7

Cartilage that covers articulating bone ends

Question 8

Synovial fliud

Answer 8

Viscous fluid that lubricates a joint

Question 9

Uniaxial joints

Answer 9

Joints that rotate around a single axis (e.g. elbow)

Question 10

Biaxial joints

Answer 10

Joints that rotate around two perpendicular axes (e.g. wrist, ankle)

Question 11

Multiaxial

Answer 11

Joints that rotate around all three perpendicular axes that define space (e.g. ball-and-socket joints - hip, shoulder)

Question 12

Vertebral column

Answer 12

Cervical spine: C1-C7
Thoracic spine: T1-T12
Lumbar spine: L1-L5
Sacral spine: S1-S5 (fused together, form rear of pelvis)
+ 3-5 coccygeal vertebrae

Question 13

Epimysium

Answer 13

sheath of connective tissue surrounding the outside of a muscle

Question 14

Perimysium

Answer 14

sheath of connective tissue surrounding a bundle of muscle fibers

Question 15

Endomysium

Answer 15

sheath of connective tissue surrounding a single muscle fiber

Question 16

Tendon

Answer 16

Strong, fibrous connective tissues that attaches muscle to bone

Question 17

Bone periosteum

Answer 17

Connective tissue that covers all bones, except at the surface of the joints

Question 18

Proximal

Answer 18

Denotes a limb muscle attachment closer the the trunk

Question 19

Distal

Answer 19

Denotes a limb muscle attachment further from the trunk

Question 20

Superior

Answer 20

Denotes a trunk muscle attachment closer to the head

Question 21

Inferior

Answer 21

Denotes a trunk muscle attachment further from the head

Question 22

Muscle fiber

Answer 22

Muscle cells; long and cylindrical with a diameter similar to that of a human hair (50-100 micrometers); multinucleate with striated appearance under magnification

Question 23

Fasciculi

Answer 23

A bundle of muscle fibers

Question 24

Sarcolemma

Answer 24

Membrane of a muscle cell

Question 25

Motor neuron

Answer 25

Nerve cell

Question 26

Neuromuscular junction

Answer 26

The junction between a motor neuron and the muscle fiber(s) it innervates

Question 27

Motor unit

Answer 27

Motor neuron + muscle fiber(s) it innervates

Question 28

Sarcoplasm

Answer 28

Cytoplasm of a muscle fiber

Question 29

Myofibrils

Answer 29

Bundles of contractile protein filaments (actin and myosin)

Question 30

Myosin

Answer 30

Thick filaments; globular head + hinge point + tail fibrous tail

Question 31

Actin

Answer 31

Thin filaments; two strands arranged in a double helix

Question 32

Crossbridge

Question 33

Sarcomere

Answer 33

The smallest contractile unit of skeletal muscle

Question 34

A-band

Answer 34

Area in the center of the sarcomere where myosin and actin overlap; length never changes length during contraction

Question 35

I-band

Answer 35

Actin only; shortens during contraction

Question 36

H-zone

Answer 36

Myosin only; shortens during contraction

Question 37

M-line

Answer 37

Center of the sarcomere (and center of the A-band) and attachment site for myosin

Question 38

Z-line

Answer 38

Defines the boundary of a sarcomere; bisects the I-band of neighboring sarcomeres

Question 39

Sarcoplasmic reticulum

Answer 39

Specialized endoplasmic reticulum in muscle cells dedicated to storage of calcium

Question 40

T-tubules

Answer 40

Invaginations in the sarcoplasmic reticulum that conduct impulses (action potentials) from the sarcolemma deeper into the cell

Question 41

Action potential

Answer 41

An electrical nerve impulse that signals the release of calcium from the sarcoplasmic reticulum into the myofibril and causes tension development in a muscle

Question 42

Sliding filament theory

Answer 42

Actin filaments at each end of the sarcomere slide inward on myosin filaments, pulling the Z-lines closer to the center of the sarcomere and shortening the muscle fiber

Question 43

Troponin

Question 44

Tropomyosin

Question 45

Power stroke

Question 46

Explain the steps of muscle contraction

Answer 46

1. Action potential travels from the motor neuron via neurotransmitter acetylcholine, which stimulates the release of calcium into the myofibril once it reaches the muscle.
2. Calcium binds to troponin, which causes tropomyosin to shift and expose protein-binding sites on actin filaments.
3. Myosin binds to actin to form a cross-bridge.
4. ATP on myosin is broken down via ATPase into ADP and phosphate, which provides energy for the power stroke (pulling action). Sarcomeres are shortened (I-band and H-zone)
5. Another molecule of ATP replaces ADP on myosin cross-bridge globular head, which detaches from active actin site and returns to its original position.
6. Stimulation of motor neuron stops, calcium is pumped back into the SR, and actin and myosin return to unbound sites.

Question 47

Acetylcholine

Answer 47

Neurotransmitter that diffuses across the neuromuscular junction and causes excitation of the sarcolemma

Question 48

All-or-none principle

Answer 48

All muscle fibers in the motor unit contract and develop force at the same time. It’s all or none!

Question 49

Twitch