Skeletal & Muscular Systems

Question 1

2 components of the skeleton:

Answer 1

cartilage and bone

Question 2

cartilage

Answer 2

• type of CT that is softer and more flexible than bone

- chondrocytes are cells responsible for synthesizing cartilage

Question 3

bone

Answer 3

-mineralized CT that can withstand physical stress

Question 4

compact bone

Answer 4

-dense bone composed of structural units called osteons

Question 5

structure of an osteon

Answer 5

-central microscopic channel called a Haversian Haversian canal surrounded by a number of concentric circles called lamellae

Question 6

spongy bone

Answer 6

• less dense, consists of bony spicules (trabeculae)

- cavities b/w spicules filled with red (blood cell formation) or yellow bone marrow (infiltrated by adipose tissue)

Question 7

osteoblasts

Answer 7

• synthesize new bone

- mature into osteocytes

Question 8

osteoclasts

Answer 8

-bone is broken down and released into the blood

Question 9

endochondral ossification

Answer 9

• existing cartilage is replaced by bone

- typically long bones

Question 10

intramembranous ossification

Answer 10

-CT is transformed into and replaced by bone

Question 11

pyramidal system

Answer 11

-provides rapid motor commands (voluntary) to skeletal muscle and other organs

Question 12

extrapyramidal system

Answer 12

-somatic motor commands as a result of processing performed at the involuntary level

Question 13

skeletal muscle

Answer 13

• responsible for voluntary movement and is innervated by the somatic nervous system
• striated

Question 14

myofibrils

Answer 14

-embedded in the fibers, further divided into contractile units called sarcomeres

Question 15

sarcoplasmic reticulum

Answer 15

-modified ER that envelopes myofibrils and stores calcium ions

Question 16

sarcolemma

Answer 16

• cell membrane of a muscle fiber

- propagates an action potential and is connected to a system of transverse tubules

Question 17

T system

Answer 17

-provides a channel for ion flow throughout the muscle fibers

Question 18

sarcomeres

Answer 18

-composed of thin (actin) and thick (myosin) filaments

Question 19

Z line

Answer 19

defines boundaries of a single sarcomere

Question 20

M line

Answer 20

runs down the center of the sarcomere

Question 21

I band

Answer 21

contains thin filaments only

Question 22

H zone

Answer 22

contains thick filaments only

Question 23

A band

Answer 23

spans the entire length of the thick filaments and any overlapping portions of thin filaments

Question 24

neuromuscular junction

Answer 24

link b/w the nerve terminal and the sarcolemma of the muscle fiber

Question 25

contraction

Answer 25

• once an action potential is generated, it is conducted along the sarcolemma and the T system into muscle fibers
• sarcoplasmic reticulum release calcium ions which bind to troponin C and initiates contraction

Question 26

rigor mortis

Answer 26

several hours after death, all the muscles in the body contract and go rigid b/c of the absence of ATP

Question 27

isotonic contractions

Answer 27

muscle shortens against a fixed load while tension remains constant

Question 28

dynamic contraction

Answer 28

change in the length of the muscle with a corresponding change in tension

Question 29

concentric contraction

Answer 29

type of dynamic concentration where the muscle fibers shorten and tension increases

Question 30

eccentric contraction

Answer 30

type of dynamic contraction where muscle fibers lengthen and tension increases

Question 31

isometric contraction

Answer 31

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

Question 32

simple twitch

Answer 32

• 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 (absolute refractory period)

Question 33

temporal summation

Answer 33

-when fibers of a muscle are exposed to frequent stimuli, muscle cannot fully relax and contractions combine to become stronger and more prolonged

Question 34

tetanus contraction

Answer 34

• contractions become continuous when the stimuli are so frequent that the muscle cannot relax
• stronger than a simple twitch

Question 35

tonus

Answer 35

• state or partial contraction

- muscles are never completely relaxed

Question 36

Cori cycle

Answer 36

-during strenuous activity, skeletal muscles convert lactic acid into glucose

Question 37

smooth muscle

Answer 37

• involuntary actions
• innervated by ANS
• lack striations, posses one nucleus

Question 38

cardiac muscle

Answer 38

-heart muscle
-striated
-one or two nuclei
involuntary, ANS

Question 39

energy reserves

Answer 39

• creatine phosphate: in vertebrates, energy is temporarily stored in this compound
• myoglobin: maintains oxygen supply in muscles by binding oxygen tightly