muscle function

Question 1

What are the three main types of skeletons?

Answer 1

endoskeletons (internal hard parts)
- sponges, echninoderms, bertabrates

Exoskeletons (external hard parts)
- most molluscs, arthropods

Hydrostatic skeletons (lack hard parts)

• fluid help under pressure in a closed body compartment
• most cnidarians, flatworms, nematodes, annelids

Question 2

Skeletal muscles do what?

Answer 2

work in antagonistic pairs

activity coordinated by nervous system

Question 3

Hydrostatic skeleton do what?

Answer 3

muscles used to change shape of fluid filled compartments, controlling animal;s form and movement

Question 4

What is peristalsis?

Answer 4

movement produced by rhythmic waves of muscles contractions from front to back

alternating contractions of circular and longitdudinal muscles

Question 5

What is the muscle hierarchy of longitudinal units?

Answer 5

1 muscle = several muscle fibres bundles

1 muscle bundle= several muscle fibers

Question 6

What is 1 muscle fibre made of?

Answer 6

1 muscle fibre has several myofibrils

Question 7

what is 1 myofibril made of?

Answer 7

1 muscle myofibril has several actin and myosin filaments, arranged in end to end sacromeres

Question 8

What happens when muscles contract?

Answer 8

Think filaments (myosin) move past think filaments (actin) –> sliding-filament model

filaments remain the same length, but the sarcomeres shorten

Question 9

muscle contraction cycles need what?

Answer 9

actin binding site on myosin

myosin binding site on actin

ATP

Ca2+

Question 10

Control of the contraction cycle:

at rest what happens?

Answer 10

myosin binding sites on actin are blocked by tropomyosin

Question 11

Control of the contraction cycle:

what happens when at AP comes along?

Answer 11

an AP in a motor neuron induces the release of acetylcholine into the neuromuscular junction

Question 12

Control of the contraction cycle:

the AP releases what ion?

Answer 12

opens voltage gated Ca2+ channels in the sarcroplasmic reticulum releasing Ca into cytosol

Question 13

Control of the contraction cycle:

Ca released into cytosol does what>?

Answer 13

ca binds to troponin; tropomyosin is pulled off myosin binding sites

ca is pumped back into the sacroplasmic reticulum

Question 14

Energetics in muscle contraction what is needed?

Answer 14

During the contraction cycle ATP is needed

it is needed to puymp Ca from cytosol back into the SR

Question 15

What are the four soures of ATP?

Answer 15

ATP pool in muscle fibre

creatine phosphate

glycolisis

oxydative phosphorylation

Question 16

how is ATP produced from ATP pool in muscle fibres?

Answer 16

only enough for a few contractions (not produced)

Question 17

how is ATP produced from creatine phosphate?

Answer 17

phosphagen (energy storage) of vertebrates

supplies phosphate group to ADP

Question 18

how is ATP produced from glycolysis?

Answer 18

splitting of glucose into pyruvate

glucose stored as glycogen

Question 19

how is ATP produced from oxidative phosphorylation?

Answer 19

production of ATP using energy derived from the redox reaction of an electron transport chain

IN MITOCHONDRIA THE POWER HOUSE OF THE CELL YOU GOT THAT ALEXXXXX

Question 20

nervous control of muscle tension

What is a motor unit?

Answer 20

motor neuron and all the muscle fibres it controls

each muscle fibres (cell )synapse with only one motor neuron, but each motor neuron can synapse with many muscle fibres

Question 21

What determines the regulation of contraction strength?

Answer 21

total number of active motor units

number of activated small or large motor units

Question 22

nervous control of muscle tension:

what are the two ways that the nervous system produces graded contractions?

Answer 22

Varying number of fibres that contract

• recrutment of multiple motor neurons results in stronger contraction
• recruitment of large motor units result in stronger contractions

varying rate at which fibers are stimulated

• a twitch results from a single action potential in a motor neurons
• rapid delivered action poteintials produce graded contractions by sumation

Question 23

What is tetanus?

Answer 23

maximal, sustained contraction of a skeletal muscle, caused by a very high frequency of APs

Question 24

What are the two sources of ATP of skeletal muscle fibres?

Answer 24

classified by ATP source and speed of contraction

Oxidative fibers

Glycolytic fibers

Question 25

What are Oxidative fibres?

Answer 25

rely mostly on aerobic respiration to make ATP

many mitochondria rich blood supply large amounts of myoglobin

dark meat in poultry and fish

Question 26

glycolytic fiber?

Answer 26

glycolysis primary source of ATP

less myoglobin than oxidative fibers, tires more easily

light meat in poultry and fish

Question 27

What are the two muscle fibres that are responsible for the speed of contraction?

Answer 27

slow twitch muscles

fast twitch fibers

Question 28

slow twitch muscle fibres are what?

Answer 28

contract more slowly but sustain longer contractions

ALL oxidative

Question 29

Fast twitch muscle fibres?

Answer 29

contract more rapidly but sustain shorter contractions

either glycolutic or oxidative

some fast glycolytic fibres can develop into fast oxidative fibres

most skeletal muscles contain both slow and fast twitch muscles in varying ratios

Question 30

what is the fastest vertebrate muscle?

Answer 30

surrounded swin bladder in male toadfish

produces characteristics mate call

can contract and relax 200x per second

Question 31

Cardiac muscles?

Answer 31

striated cells electrically connected by intercalated disks

can generate action potentials without neural input

Question 32

smooth muscles

Answer 32

found mainly in walls of hollow organs like digestice tract

contactions relatively slow and may be initiated by the muscles themsevels or by stimulation from autonomic nervous system