Chedy - theme 11

Question 1

What’s the difference between red and white meat?

Answer 1

Red has more blood. **more on this later i think

Question 2

Types of muscle tissue (vertebrates):

Answer 2

Skeletal, cardiac, smooth.

Question 3

Which types of muscle are striated? voluntary?

Answer 3

Striated: skeletal, cardiac
Voluntary: skeletal

Question 4

Levels of organization in skeletal muscle:

Answer 4

Myofibers, fascicles, muscles. Also, tendons.

Question 5

Myofibers:

Answer 5

Long, cylindrical, multinucleated cells. This means they can develop more mitochondria!

Question 6

Sarcomere:

Answer 6

Basic unit of myofiber contraction. Fibers slide over each other.

Question 7

Tendons:

Answer 7

Connective tissue that links skeletal muscle to bones

Question 8

Fascicles:

Answer 8

Bundles of myofibers bound together

Question 9

Muscles: (organizational)

Answer 9

Groupings of fascicles

Question 10

Myofilaments of myofibrils:

Answer 10

Thick filament - lots of myosin (motor protein), ATPase in A band
Thin filament - helix of two chains of actin

Thick and thin filaments interdigitate

Question 11

Actin:

Answer 11

Cytoskeletal protein that form polymers with troponin and tropomyosin

Question 12

Cross-bridges between myofilaments:

Answer 12

Projections of myosin from thick filament interacts with thin filament actin to generate force for contraction.

Question 13

Accessory proteins for contraction:

Answer 13

Titin, troponin, tropomyosin

Question 14

Titin:

Answer 14

Structural elastic proteins that align myosin and actin. Maintain the thick filament at the sarcomere - responsible for passive elasticity.

Question 15

Troponin and tropomyosin:

Answer 15

Associate with thin filament myosin. Regulate contraction by controlling cross bridges.
In the absence of Ca2+, tropomyosin covers myosin binding sites.
In the presence of Ca2+, troponin binds Ca2+ and pushes tropomyosin off of the myosin binding site so contraction can begin.

Question 16

Calcium in muscle contraction:

Answer 16

Ca is the intracellular signal for contraction. Stored in the ER of cells.

Question 17

String? Spring?

Answer 17

Muscle contraction is fibres SLIDING ACROSS each other, not condensing. NOT spring.

Question 18

Signals for muscle contraction:

Answer 18

Somatic NS motor neurons generate APs and release ACh. ACh is bound by nicotinic receptors in muscle cell membranes, which releases Ca2+ from the sarcoplasmic reticulum.

Question 19

Crossbridge structure:

Answer 19

Long tail and two heads. The tail lies along the thick filament axis and the heads form the crossbridges. Each head binds actin and ATP.

Question 20

The two roles of ATP:

Answer 20

Binding ATP to myosin weakens myosin-actin bond (but ATP is not hydrolyzed yet). Following dissociation, ATP is hydrolyzed, energizing myosin.

Question 21

The process of muscle contraction:

Answer 21

When it is hydrolyzed, the ADP, phosphate, and energy are stored in the myosin head. When myosin binds to actin, it releases the ADP and phosphate, causing the head to pull the thin filament over the thick filament.

Question 22

Muscle relaxation:

Answer 22

ATP initiates cross-bridge cycling.
*** WHAT DOES THIS MEAN

Ca2+ is taken up by the sarcoplasmic reticulum, making Ca2+ run away from troponin. Tropomyosin blocks myosin-binding sites again.

Question 23

Myosin ATPase:

Answer 23

Different muscle fibres have different forms of myosin that can hydrolyze ATP at different rates. Slow fibres go slow; fast fibres go fast. Maximal force is the same - only speed varies.

Question 24

Three kinds of muscle fibres:

Answer 24

Slow oxidative, fast oxidative, fast glycolitic.

Question 25

Oxidative fibres:

Answer 25

High capacity for oxidative phosphorylation. Lots of small blood vessels because ATP production needs blood flow for oxygen and nutrients. Lots of myoglobin as intracellular O2 reservoir. Lots of mitochondria.

Question 26

Glycolitic fibres:

Answer 26

Not that many mitochondria; lots of glycolytic enzymes and lots of glycogen. Few blood vessels. Limited oxygen use.

Question 27

Slow-oxidative fibres:

Answer 27

Low ATPase activity; lots of ATP production over time. Gets tired slowly. Used for prolonged activity.

Question 28

Fast-oxidative fibres:

Answer 28

High ATPase activity; lots of ATP production over time. Gets tired intermediately. Can be used for prolonged activity, but it’s the best at rapid activity (bird trill, rattlesnake rattle).

Question 29

Fast-glycolytic fibres:

Answer 29

High ATPase activity, but not as much ATP production over time. Powered by glycolysis. Best for short intense actions. Gets tired quickly.

Question 30

How does exercise affect muscles?

Answer 30

Increase the size of muscle (by increasing thickness of individual fibres), increase ATP producing capability

Question 31

Aerobic exercise:

Answer 31

Low intensity, long duration. Increases the number of mitochondria in slow oxidative fibres. Number of blood vessels increases. Getting stronger and increasing endurance, but not getting bigger.

Question 32

Anaerobic exercise:

Answer 32

High intensity, short duration. Increases diameter of fast glycolitic fibres by increasing myofibril synthesis. Increased synthesis of glycolitic enzymes. Increased strength and size, but not endurance.