Motor Mechanisms (Lec 5)

Question 1

hydrostatic skeleton

Answer 1

two muscles surround and act on fluid filled cavity

Question 2

two exoskeleton proteins and examples

Answer 2

calcium carbonate (clams and mussels)

chitin: lobsters and crabs

Question 3

two non-obvious organisms w/ endoskeletons

Answer 3

sponges, echinoderms,

Question 4

explain bone formation

Answer 4

osteoblasts combine Ca2+, PO43- mineral crystal, and collagen to form bone

Question 5

2 bone disorders

Answer 5

scurvy (calcium uptake deficiency) - Vit D caused

osteoporosis - resorption outpaces formation

Question 6

Which of the muscle are striated?

Answer 6

cardiac and skeletal muscle

Question 7

explain smooth muscle

Answer 7

involuntary non-striated

locations: walls of arteries, respiratory, digestive,

Question 8

which two proteins are principle in muscle contraction

Answer 8

actin and myosin

Question 9

explain the process of muscle contraction

Answer 9

1) Calcium ions from sarcoplasmic reticulum bind to troponin
2) troponin drags tropomyosin away from myosin binding sites on the actin filaments (conformational change)

3) ATP hydrolized > ADP-Pi causes conformational change of myosin (cocked/active position)
4) myosin and actin bind
5) ADP releases = power stroke (conformational change)
6) Another ATP attached, breaking bond between myosin and actin
7) Contraction stops when calcium is reabosrbed into Sarco Retic

Question 10

describe the order organization of muscle

Answer 10

level of muscle organization: 
myofibril (actin, myosin, titin)
myocyte (muscle cell)
fiber (endomysium)  
fascicle (perimysium)
muscle (epimysium)

Question 11

sarcomere

Answer 11

(repetitive contracting unit) Z-line to Z-line

Question 12

Z-line

Answer 12

dark thin protein that separate sarcomeres (cause striation)

Question 13

which parts of the sarcomere are reduced during muscle contraction

Answer 13

H-Zone and A-Band

Question 14

Explain the neurotransmitter junction of a muscle

Answer 14

Neuron releases ACh
ACh receptor is a ligand-gated ion channel that releases Na+ ions
Na+ depolarization causing AP that open Ca++ channels in sarcoplasmic reticulum, releasing Ca++ into sarcoplasm through T-tubules
This causes cross-bridge cycle and contraction
Ca2+ is reabsorbed by sarcoplasmic reticulum ending contraction

Question 15

Expain the 3 main types of muscle fibers

Answer 15

slow oxidative ~ many mitochondria and blood supply, endurance, oxidative phosphorylation, slow contraction

fast-oxidative: intermediate, many mitochondria and lots blood flow, intermediate endurance, oxidative phosphorylation, fast contraction

fast glycolytic- few mitochondria and moderate blood supply, fatigue quickly, fast contraction

Question 16

endurance training

Answer 16

increased mitochodria, myoglobin, and oxidative capacity

Question 17

sprinting and weight-lifting

Answer 17

thicker filaments, and in extreme cases new muscle cells

Question 18

satellite cells (muscle)

Answer 18

Satellite cells proliferate following muscle trauma[9] and form new myofibers through a process similar to fetal muscle development.

parabiosis experiment. Younger parabiosis enhanced the aged satellite cells (through notch signalling and affecting gene expression) which regenerated muscles rather than leaving scar tissues.

Question 19

sarcopenia

Answer 19

degenerative losse of muscle with aging

Question 20

cardiac muscle

Answer 20

smaller and only one nucleus, have gap junctions allowing ionic transfer to synchronous muscle cotnraction

Question 21

osteoclasts

Answer 21

break down bone