Module 8: The Muscular System Flashcards by Nicole P

Fascia

Dense sheet or broad band of irregular connective tissue
Lines the body wall and limbs
Supports and surrounds muscles and other organs

How well did you know this?

Not at all

Perfectly

Three layers of connective tissue extending from fascia

Epimysium
Perimysium
Endomysium
All three may extend to form a tendon

How well did you know this?

Not at all

Perfectly

Epimysium

Dense, irregular connective tissue

Encircles entire muscle

How well did you know this?

Not at all

Perfectly

Perimysium

Dense, irregular connective tissue
Surrounds groups of 10-100+ muscle fibres
Separates fibres into bundles

How well did you know this?

Not at all

Perfectly

Fascicles

Bundles of 10-100+ muscle fibres separated by perimysium

How well did you know this?

Not at all

Perfectly

Endomysium

Mostly reticular fibers
Penetrates the interior of each fascicle
Separates individual muscle fibers

How well did you know this?

Not at all

Perfectly

Sarcolemma

Plasma membrane of muscle fibres

How well did you know this?

Not at all

Perfectly

Myofibrils

Consist of myofilaments

Make up muscle fibres

How well did you know this?

Not at all

Perfectly

Sarcoplasmic reticulum (SR)

Encircle each myofibril
Stores calcium
Similar to the endoplasmic reticulum of other cell types

How well did you know this?

Not at all

Perfectly

Myofilaments

Involved in contraction

Thick and thin

How well did you know this?

Not at all

Perfectly

Thick filaments

Made of myosin

How well did you know this?

Not at all

Perfectly

Thin filaments

Made of actin

How well did you know this?

Not at all

Perfectly

T tubules (transverse tubules)

Infolding of the sarcolemma that carries the

nerve stimulus into the muscle fibre

How well did you know this?

Not at all

Perfectly

5 levels of organization in skeletal muscle

Skeletal muscle
Fascicle
Muscle fiber (cell)
Myofibril
Myofilaments

How well did you know this?

Not at all

Perfectly

Terminal cisterns

Dilated end scars of the SR
On both sides of the transverse tubule
Release Ca2+ to trigger muscle contraction

How well did you know this?

Not at all

Perfectly

Z disc

Narrow, plate-shaped regions of dense protein material

Separate sarcomeres

How well did you know this?

Not at all

Perfectly

A band

Darker middle part of the sarcomere

Extends entire length of thick filaments

How well did you know this?

Not at all

Perfectly

I band

Lighter, less dense
Contains thin filaments but no thick
Z disc passes through the center

How well did you know this?

Not at all

Perfectly

Zone of overlap

At end of A band where thick and thin filaments overlap

How well did you know this?

Not at all

Perfectly

H zone

Narrow
At centre of A band
Thick filaments but no thin

How well did you know this?

Not at all

Perfectly

M line

Middle of sarcomere
At centre of H zone
Proteins that hold thick filaments together

How well did you know this?

Not at all

Perfectly

Three proteins that build myofibrils

Contractile
Regulatory
Structural

How well did you know this?

Not at all

Perfectly

Two contractile proteins in muscle

Actin and myosin

How well did you know this?

Not at all

Perfectly

Myosin

Main component of thick filaments
Motor protein in all three types of muscle tissue
Holds thick filaments in alignment at M line

How well did you know this?

Not at all

Perfectly

Actin

Main component of thin filaments

Two regulatory proteins

Tropomyosin and troponin

Tropomyosin

Covers myosin-binding sites in actin when muscle is relaxed

Troponin

Hold tropomyosin strands in place

Titin

Large structural protein Spans half a sarcomere (connects Z disc to M line) Elasticity and extensibility

α-actinin

Structural protein in Z disc | Bind to actin and titin

Myomesin

Structural protein in M line Bind to titin Connect adjacent thick filaments

Nebulin

Long, nonelastic structural protein | Wrapped around thin filaments to anchor them to Z disc

Dystrophin

Structural protein that links thin filaments of sarcomere to integral membrane proteins of sarcolemma

Sliding filament theory

Myosin contacts with actin to form cross-bridges Myosin heads walk along thin filaments Thin filaments pulled toward M line Sarcomere shortens

Onset of contraction

SR releases Ca2+ into sarcoplasm Ca2+ binds troponin Troponin moves tropomyosin away from myosin-binding sites on actin ("frees" them)

Steps of contraction cycle

ATP hydrolysis Myosin heads bind actin to form cross-bridges Power stroke Detachment of myosin from actin

Isotonic contraction

Muscles shorten and movement occurs

Isometric contraction

Muscles do not shorten, no movement

Muscle tone

Some muscle fibers are always contracted, muscle is firm

Aerobic respiration

Glucose + oxygen → carbon dioxide + water + ATP | 38 ATP/glucose

Anaerobic respiration

Glucose → lactic acid + ATP 2 ATP/glucose but faster than aerobic Lactic acid accumulates in the muscle (burning sensation) and diffuses into blood to liver When there is sufficient oxygen liver converts it to glycogen (storage form of glucose)

Metabolism of creatine phosphate

Creatine phosphate + ADP → creatine + ATP

Origin

End of the muscle that is attached to the stationary bone

Insertion

End of muscle that is attached to the movable bone

Deltoid

Shaped like a triangle

Latissimus

Wide

Orbicularis

Circular

Serratus

Serrated

Teres

Long and round

Trapezlus

Shaped like a trapezoid

Brevis

Short

Longus

Long

Maximus

Large

Minimus

Small

Minor

Smaller

Vastus

Huge

Rectus

Straight

Transverse

Across

Biceps

Two heads

Triceps

Three heads

Quadriceps

Four heads

Fixator

Synergist that immobilizes bone

Lever

Rigid structure that can move around a fixed point

Fulcrum

Fixed point that levers move around

Two different forces acted on levers

Effort - causes movement | Load or resistance - opposes movement

Mechanical advantage

Load is closer to fulcrum, effort is farther | Small effort required to move a large load over a small distance

Mechanical disadvantage

Load is farther from the fulcrum, effort is applied closer | Larger effort required to move a small load, but at a greater speed

First-class lever

Fulcrum is between effort and load Example: scissors, seesaws, chewing Mechanical advantage or disadvantage depending or whether effort or load is closer to the fulcrum

Second-class lever

Load is between fulcrum and effort Example: wheelbarrow, standing up on toes Always produce mechanical advantage because the load is always closer to the fulcrum than the effort (produces the most force) Uncommon in human body

Third-class lever

Effort is between load and fulcrum Example: forceps Most common in the body Always produce mechanical disadvantage because effort is always closer to the fulcrum than the load