Muscular Tissue

Question 1

what causes contraction in a muscle

Answer 1

protein actin pulled by protein myosin; only in striated muscles after binding sites are exposed in response to calcium and proteins troponin and tropomyosin

Question 2

how many nucleuses do skeletal, cardiac, and smooth muscles have

Answer 2

skeletal: multinucleated
Cardiac: 1-2 nuclei
smooth: 1 nuclei

Question 3

whats the difference between cardiac and skeletal muscle

Answer 3

cardiac has 1 nuclei; muscle fibers are shorter; possess many mitochondria & myoglobin; branched & connected by intercalated disc

Question 4

intercalated discs

Answer 4

apart of sarcolemma; allow cardiac muscle cells to contract in wave-like pattern so heart can pump

Question 5

gap junction in cardiac cells

Answer 5

forms channels between muscle fibers that allow depolarizing current produced by cations to flow from cardiac muscle cells

Question 6

desmosomes

Answer 6

cell structure that anchors ends of cardiac muscle fibers together so cells do not pull apart during stress of individual fibers contracting

Question 7

what nervous system do pacemaker cells respond to

Answer 7

autonomic nervous system; controls heart rate

Question 8

functional syncytium

Answer 8

begins w/ pacemaker cells; wave of contraction that allows heart to work as a unit

Question 9

features of smooth muscle fibers

Answer 9

spindle shaped like football; single nucelus; thousands times shorter than skeletal fibers; produce their own connective tissue endomysium; no striations but do contain actin/myosin

Question 10

do smooth muscles contain troponin?

Answer 10

no they have protein called calmodulin; Ca++ binds to calmodulin to activate enzyme myosin kinase which attach to thin filaments & when those move past thick filaments it stimulates pull and contraction of muscle

Question 11

smooth muscle energy

Answer 11

power output low but contractions must continue always, so Ca++ always present to maintain muscle tone

Question 12

motor units

Answer 12

axon-like swelling called “boutons” from autonomic neurons form motor units through smooth muscle

Question 13

what are the 2 different smooth muscles & locatoins

Answer 13

single unit: walls of visceral organs; has its muscle fibers joined by gap junctions so that they contract as one unit; aka visceral muscle; has stress-relaxation response meaning they can stretch & fill w/out releasing contents
multi unit: rarely posses gap junctions; contraction does not spread cell to cell; stimuli comes from ANS & hormones not stretching; large blood vessels/resp tract

Question 14

hyperlasia

Answer 14

smooth muscle can divide to produce more cells, ex. uterus at puberty

Question 15

epimysium

Answer 15

irregular connective tissue wrapped around each muscle fiber

Question 16

fascicle

Answer 16

individual skeletal muscle fiber

Question 17

perimysium

Answer 17

middle layer connective tissue inside each fascicle

Question 18

endomysium

Answer 18

in each fascicle; encases muscle fiber; thin connective tissue; made of collagen & reticular fibers

Question 19

aponeurosis

Answer 19

aka fascia; connective tissue between skin & bones; ex. lats

Question 20

sarcolemma

Answer 20

plasma membrane of skeletal muscle fibers

Question 21

sarcoplasmic reticulum (SR)

Answer 21

stores releases and retrieves CA++

Question 22

actin

Answer 22

thin filaments

Question 23

myosin

Answer 23

thick filament

Question 24

sarcomere

Answer 24

packet of microfilaments & proteins such as troponin & tropomyosin; bordered by z-discs; run entire length of muscle fiber;

Question 25

neuromuscular junction

Answer 25

where muscle fiber first responds to signaling by motor neuron; where motor neurons terminal meets muscle fiber

Question 26

excitation-contraction coupling

Answer 26

process involved in skeletal muscle contraction; skeletal muscle fibers to contract; sweeps through sarcolemma; Ca++ is released from SR; myosin then pulls actin filaments towards center & shortens muscle

Question 27

t-tubules role

Answer 27

carry action potential into interior cell to trigger opening of calcium channels in membrane of adjacent SR; causes Ca++ to diffuse out into sarcoplasm and trigger muscle contraction

Question 28

what stimulates muscle contraction

Answer 28

Na+ enters & releases Ca++ from SR sustained by ATP

Question 29

what is the sliding filament of contraction

Answer 29

signaled by motor neuron; thin filaments are pulled & slide over thick filaments w/sacromeres when Ca++ enters sarcoplasm

Question 30

tropomyosin

Answer 30

winds around chains of actin filament covers myosin binding sites to prevent actin from binding there; topomyosin binds to troponin & Ca++

Question 31

cross-bridge formation

Answer 31

tropomyosin exposes myosin binding site on actin filament; Ca++ binds to troponin & move tropomyosin; then thin filaments are pulled by myosin heads to slide past thick filaments toward sarcomere

Question 32

what are the three ways ATP can be regenerated

Answer 32

creatine phosphate metabolism; anaerobic glycolysis & fermentation; aerobic respiration

Question 33

creatine phosphate

Answer 33

molecule that can store energy in phosphate bonds; atp transfers energy to creatine & this can be used during first 15 seconds of energy source

Question 34

anaerobic glycolysis & fermentation

Answer 34

second source of energy; non oxygen dependent process that breaks down glucose to produce ATP; slower than creatine phosphate; breaks down glycogen stores & converts to lactic acid; good for short bursts of energy

Question 35

aerobic respiration

Answer 35

breakdown of glucose in presence of oxygen produces CO2 H2O and ATP; takes place in mitochondria; this provides ATP for resting/moderate activity; uses circulating glucose in blood stream/pyruvic acid/fatty acids; increases efficiency of circulatory system so o2 can be supplied to muscles longer

Question 36

what type of molecule is myoglobin

Answer 36

protein

Question 37

what are the products of atp hydrolyzation

Answer 37

ADP and Phosphate

Question 38

when muscle atrophies what happens

Answer 38

number of sacromeres & myofibrils decreases

Question 39

what is two criteria to consider when classifying types of muscle fibers

Answer 39

how fast some fibers contract relative to others & how fibers produce ATP

Question 40

three main types of skeletal muscle fibers

Answer 40

1. slow oxidative fibers contract relatively slowly & use aerobic respiration 2. fast oxidative fibers have fast contractions & primarily use aerobic respiration but fatigue quicker than SO fibers 3. fast glycolytic fibers have fast contractions & primarily use anaerobic glycolysis; fatigue the quickest

Question 41

angiogenesis

Answer 41

formation of more extensive capillary networks around the fiber; supply O2 & remove metabolic waste

Question 42

insertion of a muscle

Answer 42

moveable end of the muscle that attaches to the bone being pulled

Question 43

origin

Answer 43

end of the muscle attached to a fixed bone

Question 44

antagonist

Answer 44

maintain body/limb position; control rapid movement

Question 45

what are the main 6 major fascicle arrangements

Answer 45

parallel, fusiform, circular, convergent, bipennate, unipennate, multipennate

Question 46

what are the 4 pairs of abdominal muscles

Answer 46

external oblique, internal oblique, transversus abdominis, rectus abdominis

Question 47

linea alba

Answer 47

fibrous band that is bilateral rectus sheaths that join anterior midline of body; enclose rectus abdominis