Muscle, skin, tissue, etc Flashcards Preview

MCAT - Bio/Biochem > Muscle, skin, tissue, etc > Flashcards

Flashcards in Muscle, skin, tissue, etc Deck (34):
1

What are the principle descriptors of skeletal muscle?

1. Voluntary
2. On bones
3. Multinucleate
4. Striated

2

What is the hierarchy of muscle components/cells

Actin + Myosin -> sarcomere -> myofibril -> myofiber (now considered the muscle CELL--contains organelles and cytoplasm) -> fascicle -> whole muscle

3

The sarcoplasmic reticulum stores what?

Calcium

4

The sarcoplasmic reticulum acts like a net that surrounds bundles of what?

myofibrils

5

How does the calcium stored in the sarcoplasmic reticulum reach into the innermost part of the myofibril bundle?

T tubules! Go crosswise across muscle cell, allowing AP to travel to the interior of the cell.

6

What level of muscle complexity is the initial unit of contraction?

Sarcomere

7

What kind of filament(s) make(s) up the I band?

Actin only

8

What kind of filament(s) make(s) up the A band?

Actin and myosin

9

What kind of filament(s) make(s) up the H zone?

myosin only

10

What part of the sarcomere "disappears" during contraction?

H zone disappears and I band shrinks greatly

11

What step(s) in actin-myosin binding require ATP?

1. The PRESENCE (but not hydrolysis) of ATP is required for myosin to release actin after the power stroke.

2. ATP hydrolysis is used to reset the myosin head to a "high energy conformation"

12

Does the power stroke of actin-myosin binding require ATP?

NO!

13

When you run out of ATP, your muscles can't _________.

Relax! This is why rigor mortis occurs.

14

Do myosin head groups act synchronously or asynchronously?

Asynchronously

15

What does tropomyosin do?

Covers up the myosin binding sites so that actin and myosin cant interact

16

What does troponin do?

When calcium is released, it binds to troponin, tugging tropomyosin out of the way so that it no longer blocks the myosin binding sites -> myosin can bind to actin -> filaments slide (contraction)

17

What causes release of calcium from the sarcoplasmic reticulum?

Depolarization of the cell (SR) -> opens voltage-gated calcium channels and calcium floods the cytosol, binds to troponin

18

What is a motor unit? How would you describe contraction at this level?

A motor neuron and all the muscle cells it controls.

Contraction at this level is all or none.

19

In what is the first energy used by muscle cells?

Phosphocreatine

20

What molecule stores oxygen in the muscles?

Myoglobin

21

What things cause the oxyhemoglobin saturation curve to shift to the right?

1. Increased CO2
2. Increased temp
3. Decreased pH

22

What are the characteristics of Type II muscle fibers? Which is the fastest?

White
Contract fast
Contract strongly
Fatigues easily
Low myoglobin
Low mito
Low blood supply

Type IIB = the fastest of all

23

What are the characteristics of Type I muscle fibers?

Red
Contract slowly but for longer
Not as strong
High myoglobin
High mito
Highly vascular

24

What are the regions of a long bone and what are they made of?

long shaft called diaphysis made of compact bone and yellow marrow (fat). The innermost region that contains the marrow is called the medullary cavity.

+ 2 collagenous growth plates at each end

The knobs at the ends are made of spongy bone and are called epiphysis

25

What is an osteocyte?

Mature bone cell, dormant

26

Compact bone is made of many __________.

Osteons

27

What is at the center of each osteon?

A central canal to bring blood and exchange nutrients and waste with the osteocytes via canaliculi

28

What type of cell builds new bone?

Osteoblast

29

What is the larynx made out of?

Cartilage

30

What prevents food from entering the trachea while swallowing?

The epiglottis

31

What is the purpose of surfactant?

Reduce surface tension in the lungs

32

Describe cardiac muscle

1. Striated
2. Branched
3. Mononucleate
4. Connected via gap junctions

33

Where is red marrow found?

Spongy part of flat and long bones (epiphyses/knobs of long bones)

34

Which of protein binds calcium in smooth muscle cells?

Calmodulin