Muscle 1

Front 1

Myosin and Thick Filaments

Back 1

3 thick filaments have a 3D structure, within myosin molecules arrayed around the circumference of the thick filament

Front 2

Myosin Structure

Back 2

Long tail, 2 heads, all tails point towards center

Front 3

Even though each myosin has 2 heads, at any one time only one head can be bound and form a .....

Back 3

cross bridge

Front 4

Each Myosin Head has two binding sites:

Back 4

1 Actin Binding Site

1 ATP Binding Site: power the movement of myosin
(power the cross bridge cycle)

Front 5

The head of Myosin acts like a...

Back 5

ratchet.

binds to actin, then changes confirmation and slides the thin filaments towards center of sarcomere

Front 6

3 Proteins of a Thin Filament

Back 6

Globular-Actin: "twisted pearl strand"
chains of actin molecules twisted
into helices

Actin covered by:
Tropomyosin: regulatory protein
blocks myosin binding site on actin

Attached to tropomyosin:
Troponin: regulatory protein
a: troponin t - portin bound to tropomyosin
b: troponin c - portion of troponin that will bind to calcium

Front 7

Three subunits of Troponin

Back 7

TnT: portion bound to tropomyosin

TnC: portion that will bind to calcium

TnI:

Front 8

What happens to a thin filament in the absence of calcium?

Back 8

tropomyosin blocks the myosin binding site on the actin, preventing cross bridge attachment

Front 9

When can't myosin bind to actin?

Back 9

When tropomyosin blocks the cross bridge binding site on actin in a relaxed skeletal muscle

Front 10

When will muscle contraction occur?

Back 10

When you get calcium ions inside the cell to bind to troponin

this complex then pulls tropomyosin away from the cross bridge binding site, allowing myosin to bind to actin

Front 11

Absence of calcium vs presence of calcium

Back 11

absence: no binding

presence: myosin binds to actin

Front 12

Where is calcium stored?

Back 12

sarcoplasmic reticulum


*form of smooth endoplasmic reticulum

Front 13

Sliding Filament Theory

Back 13

filaments slide past one another

thin towards center of sarcomere, no change in length

Front 14

Calcium enters, binds to troponin, opening the binding site


Myosin binds, changes its confirmation in ratchets, slides thin filaments towards the center

Back 14

X

Front 15

Force exerted by each myosin head

Distance moved

Back 15

10 pN

10nm

Front 16

What does ATP do in the cross bridge cycle?

Back 16

breaks bond between myosin and actin

resets myosin head to prepare for another cycle

provides energy for "power stroke:" movement of myosin

Front 17

Neuromuscular Junction

Back 17

Where the motor nerve innervates the muscle fiber


similar structure to a synaptic cleft

Front 18

Motor Units

Back 18

motor nerve plus all of the muscle fibers that it innervates

Front 19

Where would you want a small motor unit? How about a large?

Back 19

Small: Eyes, fine control

Large: Limbs

Front 20

Unlike a nerve synapse... at the Neuromuscular junction:

Back 20

An AP in the motor nerve causes an AP in the skeletal muscle

1:1

Front 21

Action Potential in the motor neuron cause ______ release into the neuromuscular junction

Back 21

Acetylcholine (Excitatory NT)


Muscle contraction follows the delivery of ACh to the muscle fiber

Front 22

T-Tubule

Back 22

conduct electrical depolarization of the sarcolemma into the muscle cell interior

*Associated with the sarcoplasmic reticulum

Front 23

As an AP travels along the t-tubule, it opens what kind of channel?

Back 23

change in voltage activates a voltage gated receptor known as a DPH receptor

Front 24

DPH receptor senses the t-tubule voltage and causes, open this receptor:

Back 24

ryanodine receptor (essentially a modified calcium channel) on the sarcoplasmic reticulum


calcium ions released into the cytosol bind to troponin

Front 25

Tension of a Single Muscle Fiber Depends On:

Back 25

1. Number of cross bridges
2. Length at time of stimulation
3. Frequency of stimulation

Front 26

Single Fiber Force Production

Back 26

"All or none" principle

Either contracted (active) or relaxed

Front 27

The larger the CSA activated...

Back 27

The more force you can produce

Front 28

Increase whole muscle force by:

Back 28

Activate more motor units

Front 29

What is force directly proportional to?

Back 29

Cross Sectional Area

Front 30

Whole Muscle Force Depends on:

Back 30

- Contraction Type
- Velocity
- Muscle Fiber Type
- Muscle Architecture

Front 31

4 Types of Skeletal Muscle Contraction

Back 31

- Isotonic
- Isometric
- Eccentric
-Concentric

Front 32

Are concentric contractions and eccentric contractions isotonic?

Back 32

NO!

Front 33

Why are isotonic contractions studied in a lab?

Back 33

Can't do in a moving joint.

As you move through a range of motion, the force your muscle has to produce changes

Isotonic means "Same Force"

Front 34

Isometric Contraction

Back 34

Constant length contraction

Front 35

Eccentric Contraction

Back 35

Occurs when a muscle is active but being lengthed

Front 36

Concentric Contraction

Back 36

Occurs when a muscle is active and shortens

Front 37

How does an Isotonic contraction happen?

Back 37

attach muscle to a lever, then attach it to a weight, stimulate muscle

weight has to be light enough for muscle to shorten

force increases then levels out

force levels out: contraction begins, muscle shortens

Force the same, length changes

Front 38

Describe an Isometric Contraction

Back 38

Length doesn't change

Muscles are active, contracting, producing force

Front 39

Muscle Fiber Types

(Forms of Myosin)

Back 39

Fast Glycolytic (FG)

Slow Oxidative (SO)

Fast Oxidative Glycolytic (FOG)

Front 40

Fast Glycolytic Fibers

Back 40

White meat on the turkey

Produce high forces

low numbers of mitochondria, myoglobin, and blood capillaries


rely upon glycolysis for ATP: lactic acid build up = rapid fatigue

Front 41

Slow Oxidative Fibers

Back 41

Dark Meat Fibers

produce low levels of force

highly vascularized

abundant mitochondria

oxidative phosphorylation: slow fatigue

Front 42

Fast Oxidative Glycolytic Fibers

Back 42

Intermediate between FG and SO fibers

produce more force than SO, but less than FG

fairly fatigue resistant

Front 43

Slow twitch, Red, Type I Fibers

Back 43

Slow Oxidative

Front 44

Fast twitch, White, Type II FIbers

Back 44

Fast Glycolytic

Front 45

Example of SO fibers

Back 45

postural muscles

responds well to repetitive stimulation without becoming fatigued

Front 46

Examples of FG fibers

Back 46

muscles used in sprinting or jumping


quick bursts of strong activation

Front 47

Examples of FOG fibers

Back 47

muscles used in walking


responds quickly AND to repetitive stimulation without becoming fatigued.

Front 48

Characteristics of slow fibers

Back 48

smaller diameter
darker color (myoglobin)
fatigue resistant
Aerobic ATP synthesis
low glycogen content

Front 49

Characteristics of fast fibers

Back 49

larger diameter
paler color
easily fatigued
Anaerobic ATP synthesis
abundant glycogen

Front 50

Size Principle of Muscle recruitment

Back 50

when you want to produce more force, recruit smallest fibers first:

SO fibers, then activate FO, then activate FOG

Front 51

Muscle Hypertrophy

Back 51

muscles can grow from heavy training


Increase diameter of muscle fibers

increase the # of myofibrils

increase amount of mitochondria

increase amount of glycogen

CANNOT INCREASE 3 of MUSCLE FIBERS, just increase their diameter.

CSA that matters, not diameter (Force proportional to CSA)

Front 52

Muscle Atrophy

Back 52

reduction in muscle size and muscle tone at rest as a result of muscle inactivity


reduction in force, and hence its power

Front 53

Anaerobic activity

Back 53

Sprinting, weight lifting

Tend use more fast fibers, fibers that fatigue more rapidly

Front 54

Aerobic activity

Back 54

Prolonged activity: long distance running and swimming

Supported by mitochondria

Require oxygen

More FOG, less FO

Front 55

Muscle Fiber Types

Back 55

What you don't use, you lose

Muscle fibers break down proteins, become smaller and weaker

With prolonged inactivity, fibrous tissue may replace muscle fibers

Front 56

Name two ways to increase CSA

Back 56

change fiber type

activate more motor units

Front 57

Muscle Architecture - Parallel or Fusiform

Back 57

long chains of muscle fibers

Designed for muscles that undergo shortening contractions that produce work

Muscles usually contract over long distances

Front 58

example of a muscles with fusiform architecture

Back 58

sartorius or biceps brachii

Front 59

Muscle Architecture - Convergent

Back 59

Muscles converge onto a single insertion

Increase CSA

allow for intermediate length change while staying stable

Front 60

example of a convergent muscle architecture

Back 60

Pectoralis Major

Front 61

Muscle Architecture: Pennate

Back 61

designed to have a large CSA

designed to produce force

NOT designed to shorten over long distance

Front 62

Unipennate Muscles

Back 62

One group of fibers coming into a single tendon

fibers arranged to insert diagonally, allowing for great strength

ex: digitorum longus

Front 63

Bipennate Muscles

Back 63

two rows of muscle fibers, facing in opposite diagonal directions, with a central tendon (like a feather)

great power, but less range of motion

ex: rectus femoris

Front 64

Multipennate Muscles

Back 64

multiple rows of diagonal fibers, with a central tendon that branches into two or more tendons


ex: deltoid

Front 65

What is the advantage of muscle architecture where there are short fibers placed at an angle?

Back 65

INCREASES CROSS SECTIONAL AREA

thus, increase force

ex: deltoid

Front 66

Parallel muscles are usually long and have good what?

Back 66

endurance

Front 67

Skeletal muscles are named by:

Back 67

Action

Movement they produce

Occupations or habits

Location

Origins and Insertions

Fascicle Orientation

Relative Position

Structural Characteristics

Front 68

Skeletal Muscles Named By Movement

Back 68

Flexor, Extensor, Adductor, Abductor

Front 69

Skeletal Muscles Named By Occupation or Habits

Back 69

Riser muscles involved with laughter

Front 70

Skeletal Muscles Named By Location in Body

Back 70

Identifies body regions


abdominal obliques cover abdominal cavity;
Temporalis muscle

Front 71

Skeletal Muscles Named By Origin and Insertion

Back 71

First part of name indicates origin, second part indicates insertion

Sternocledomastoid
Supraspinatus
Infraspinatus
Subscapularis

Front 72

Skeletal Muscles Named By Fascicle Orientation

Back 72

describes fascicle orientation within the muscle


obliques, rectus abdominus, transverse abdominus

Front 73

Skeletal Muscles Named By Relative Position

Back 73

extrinsic

intrinsic

ex:
superficialis tendon
external obliques
internal obliques

Front 74

Skeletal Muscles Named By Structural Characteristics

Back 74

Number of tendons they have

shape: trapezius, rhomboid, deltoid, biceps (Bi for 2 heads)

size

Front 75

Skeletal Muscles Named By Action

Back 75

Masseters involved in mastication

Front 76

Appendicular Musculature

Back 76

Position and stabilize pectoral and pelvic girdles

Move upper and lower limbs

Two divisions:
muscles of shoulders and upper limbs
muscles of pelvis and lower limbs

Front 77

Major muscles that move the pectoral girdle

Back 77

trapezius
rhomboid
serratus anterior
deltoid
supraspinatus
infraspinatus
teres minor

Front 78

Muscles that move the arm

Back 78

subscapularis
teres major
deltoid
supraspinatus
pectoralis major
latissimus dorsi

Front 79

The Rotator Cuff

Back 79

Muscles involved in shoulder rotation and stabilization

Subscapularis
Infraspinatus
Supraspinatus
Teres Minor