Bio Class 10

Question 1

Function of muscles

Answer 1

Voluntary control

Question 2

Location of muscles

Answer 2

On bones

Question 3

Nuclei in muscles

Answer 3

Multinucleated

Question 4

Microscopic appearance of muscles

Answer 4

striated

Question 5

Hierarchy of muscle composition

Answer 5

Protein filaments (actin & myosin) –> Sarcomere (arrangement of myosin & actin in a specific way) –> myofibril (sarcomere lined end to end) –> muscle cell fiber *myofiber (bundle of myofibrils + plasma membrane, some organelles, fibroblast) –> fasicle (bundle of myofiber) –> whole muscle (bundle of fasicles)

Question 6

Which muscles have sarcomeres?

Answer 6

Cardiac muscles

Question 7

Why do skeletal muscles have t-tubules?

Answer 7

Skeletal muscle is really thick so need T-tubules to carry AP deep into cell

Question 8

H-zone

Answer 8

Region of only myosin

Question 9

A band

Answer 9

Region of entire myosin with some actin

Question 10

I band

Answer 10

Region of actin between each myosin

Question 11

Z line

Answer 11

Beginning to end of each sarcomere

Question 12

What happens to the sarcomere upon contraction?

Answer 12

H zone & I band will disappear, A band will remain the same; myosin will attach to actin and pull it closer bringing the Z line closer to myosin each time

Question 13

Sliding Filament Theory

Answer 13

1. Myosin head will bind to actin in presence of Ca2+; also called “cross bridge formation”
2. Myosin pulls actin towards center of sarcomere; called “power stroke” but NO ATP
3. In presence of ATP, myosin will bind to ATP and release actin
4. Myosin resets to high energy conformation; requires ATP hydrolysis

After each round of steps 1-4, Z line will get closer and closer to thick filament

Question 14

Excitation-Contraction Coupling

Answer 14

Tropomyosin binds to actin and blocks the sites of myosin binding

• tropomyosin is attached to troponin which has a binding site for Ca2+
• When Ca2+ is present, troponin will make tropomyosin move apart, unblocking the myosin sites which will allow contraction to happen

Question 15

What happens to muscles when you run out of ATP?

Answer 15

You can’t relax, myosin will stay bound to actin and you will stay contracted

Question 16

Do myosin heads operate asynchronously or synchronously?

Answer 16

Asynchronously because if they worked in the same way then they would all bind to actin at the same time & release at same time so the Z line will just snap back to its original position

Question 17

Bohr-shift

Answer 17

Shift to right:
increases carbon dioxide
increases temperature
decreases pH

Question 18

What happens to oxygen affinity & delivery during exercise?

Answer 18

Hb affinity to o2 during exercises decreases, while delivery to tissues increases
- will shift to the right

Question 19

Motor Unit

Answer 19

motor neuron and all muscle cells under its control

Question 20

Large Motor unit vs small motor unit

Answer 20

Large
- 1000 muscle cells per neuron

Small
- 10-20 muscle cells per neuron

Question 21

Gross vs fine motor control

Answer 21

Gross

• Eg. big scale movements like running
• few large motor units

Fine

• Eg. precision so things like eye movement
• many many small motor units

Question 22

How can you address oxygen debt?

Answer 22

1. Replenish oxygen on myoglobin
2. Convert lactic acid to something useful (so you want to oxidize lactic acid back to pyruvate or maybe even all the way to glucose through gluconeogenesis)

Question 23

Muscle Energy Sources

Answer 23

1. Creatine-P + ADP –> Creatine + ATP
2. Glycolysis
3. Aerobic Respiration (Krebs, PDC, ETC)

Question 24

Myoglobin

Answer 24

Stores oxygen

- one polypeptide so no cooperative binding

Question 25

Fiber Types

Answer 25

Slow twitch Fast Twitch Type IIA Fast Twitch Type IIB

Question 26

``` Slow Twitch: Myoglobin Content Capillary Network Speed of contraction Mitochondrial # Fatigue resistance Force generated Example ```

Answer 26

- also known as "red slow twitch or red oxidative fibers" - high with myoglobinc - dense capillary network - slow contaction - high mito # - extended contraction with no fatigue - low force - Eg. Leg muscle of marathon runner

Question 27

``` Fast Twitch Type IIa: Myoglobin Content Capillary Network Speed of contraction Mitochondrial # Fatigue resistance Force generated Example ```

Answer 27

- also known as "fast twitch oxidative fibers" - lower myoglobin - less dense capillary network - intermediate contraction - some mito # - ~30 mins - medium force - Eg. Leg muscle of 400 m fast runner

Question 28

``` Fast Twitch Type IIb: Myoglobin Content Capillary Network Speed of contraction Mitochondrial # Fatigue resistance Force generated Example ```

Answer 28

- also known as "white fast twitch fibers" - very low myoglobin - very few capillary network - fast contraction - very few mito # - ~1 min - explosive force - Eg. Chicken breasts

Question 29

Cardiac vs Smooth Muscle

Answer 29

Cardiac - uninucleated - involuntary - in heart - striated (actin & myosin organized into sarcomeres) Smooth - uninucleated - involuntary - walls of hollow organs - nonstriated (myosin and actin randomly in place)

Question 30

_____blast vs _____cyte

Answer 30

- blast: - still dividing - produces the matrix - immature bone cells - cyte: - not dividing - maintains matrix - mature bone cells

Question 31

What is the matrix composed of?

Answer 31

``` Fibers (elastic or collagen) Glop substance (liquid = plasma, solid = bone) ```

Question 32

Bone function (skeletal system function)

Answer 32

1. Support & movement 2. Protection 3. Mineral storage 4. Blood cell formation

Question 33

Long Bone anatomy

Answer 33

2 epiphysis & a diaphysis - epihysis is protruding end with spongy bone - diaphysis is composed of compact bone