Anatomy and Physiology: Chapter 6 The Muscular System

4 functions of muscles

1. producing movement

2. maintaining posture

3. stabilizing joints

4. generating heat

explain producing movement

• muscle contraction

• respond to changes

• express emotions

explain generating heat

• byproduct of muscle activity

• ATP used to power energy

• energy escapes as heat

• skeletal muscle= 40% of muscle mass= most heat generated

what muscles have the largest muscle fibers

skeletal muscle

cell appearance of skeletal muscle

long and cylindrical

multinucleic

obvious striations

control is ______ through ______

voluntary reflexes

skeletal muscle contracts ______ and tire ______

rapidly, easily

1 muscle cell

muscle fiber

muscle fibers bundled together by

connective tissue

muscle fibers

• cells are _____ and arranged in ____

• muscle fibers packed into _____ muscle

elongated, fibers, skeletal

bundle of muscle fibers

fascicles

delicate connective tissue sheath surrounding each muscle fiber

endomysium

connective tissue encasing each fascicle

perimysium

“overcoat” of connective tissue, covers entire muscle

epimysium

• many fascicles bound together

• blends into tendon to attach to bone

epimysium

cell membrane of a muscle cell

sarcolemma

sarcolemma

• contains _______ material for anchoring _____ to each other

• connects muscle cells to _____ covering

polysaccharide, cells, tissue

contain ribbon like organelles, gives striped appearance, light and dark

• banding pattern gives working function

myofibils

tiny chains of contractile myofibils arranged end to end

• arranged into smaller structures

sacromeres

thread- like protein strands within sacromeres

myofilaments

2 kinds of myofilaments

1. thick

2. thin

made of myosin, contain enzymes to split ATP to generate power for muscle contractions

thick filaments

made of actin

thin filaments

what are the 4 special functional properties of muscle cells

1. responsiveness

2. contractility

3. extensibility

4. elasticity

ability to receive and respond to change

responsiveness

ability to shorten when stimulated

contractility

ability to be stretched

extensibility

ability to recoil and resume resting length after stretching

elasticity

muscle cells must be stimulated by

nerve impulses

one neuron and all the muscle cells it stimulates

motor unit

the neuron of a motor unit reaches _____ and its _____

muscle, branches

space between neurons and muscle cells

synaptic cleft

synaptic cleft

• filled with _______

• cells never _____

interstitial fluid, touch

neurotransmitter that specifically stimulates skeletal muscle

Acetylcholine (ACh)

ACh

• released by _____

• influences ___ and __levels in cells

nerve impulses, NA+, K+

electrical current generated by “upset” of NA+ and K+, impulse travels

action potential

action potential acts on filaments to ____ and ____ muscle

slide, contract

explain the process of a muscle contraction

1. nerve impulse reaches end of neuron

2. calcium channels open and calcium enters into neuron

3. entry of calcium causes release of ACh

4. ACh diffuses across synaptic cleft and binds to receptors in sarcolemma

5. ACh bonds to sodium potassium channels in cell membrane

6. upset leads to action potential

7. enzyme breaks down ACh ending the process

what causes the upset in the electrical conditions

NA+ enters and K+ leaves but not enough, so there is too much positive charge inside

1 nerve impulse produces how many contractions

1 contraction

nerve cells send impulses VERYrapidly so there is no evidence of

relaxation

muscle cells will ALWAYS fully contract, never partially. the reactions just change for different things

All or none lawdifferent

different degrees of contraction

graded response

graded response

• ____ of simulation

• _____ of muscle cells being stimulated

frequency, amount

2 types of muscle contractions

1. isotonic

2. isometric

tension, myofilaments slide, muscle shortens, movement occurs

• ex) bending knee, raising arms, smiling

isotonic

tension, myofilaments trying to slide, muscle pitted against less movable object, bones do not move

• ex) lifting 500lb weight, pushing against wall

isometric

single, brief, jerky contraction

• impulse is delivered rapidly

• muscle cannot relax between contraction

muscle twitches

what can cause muscle twitches

stress, anxiety, fatigue, dehydration, damaged nerves, circulation issues, vitamin/mineral deficiency

energy for muscle contractions come from

breakdown of ATP

in a regular muscle contraction, 1 ATP gives you ____ seconds of contraction

4-6

3 additional ways to regenerate ATP

1. phosphorylation of ADP

2. Aerobic respiration

3. Anaerobic glycolysis and fermentatoin

explain phosphorylation of ADP by creatine phosphate

• ________ high energy molecular found in muscle cell

• CP _____ to _____

• _______ molecule transferred from ___ to ___'

• creation of _____

• ___seconds of contraction

creatine phosphate (CP)

broken down, creatine

phosphate, CP, ADP

ATP

15

explain aerobic respiration

• ___ broken down by _____

• requires continuous presence of _____ and _____

• _____ created for _____ glucose

• ____ process

• energy for contractions ____ seconds or longer

• ____ energy use

glucose, mitochondria

oxygen, nutrients

32 ATP, 1

slow

30

long term

explain anaerobic glycolysis and fermentation

• ___ muscle activity

• lack of ____

• ____ required

• ____ times faster

• ___to____ seconds of strenuous activity

• causes ______ and _______

intense

oxygen

glucose

2.5

30, 60

muscle fatigue, soreness

muscle is unable to contract even though it is still stimulated

muscle fatigue

muscle fatigue

• working muscle tire ____ rest

• contractions become ___

• results from lack of ____

• if activity is not stopped ______

without, weaker, oxygen, muscles give out

regular muscle size increases these 3 things

muscle size, strength, and endurance

2 types of exercises

1. endurance

2. resistance

stronger, more flexible muscles, resistant to fatigue, muscles do not increase in size

ex) running and biking

endurance exercise

muscles pitted against object, muscle contracts with force, enlargement of muscle

ex) weight lifting

resistance exercise

muscle movements depends on

attachment of muscle

part of muscle attached to the immovable bone directly

origin

part of muscle attached to the movable bone, tendon

insertion

what is the origin and insertion when using your bicep (bending your arm)

origin- humerus

insertion- ulna, radius

decrease the angle of joint, brings two bones closer together

ex) bend arm

flexion

opposite of flexion, movement that increases angle or distance between two bones

ex) straighten arm

extension

movement of bone around its longitudinal axis, medial or lateral

ex) moving head to look out then back in

rotation

moving a limb away from the midline

ex) lifting arm out to side

abduction

opposite of abduction, movement of a limb towards the midline

adduction

combination of flexion, extension, and abduction

• proximal end of limb is stationary

• distal ends moves in a circle

• ex) arm circles

circumduction

lifting foot towards shin

ex) standing on heels (flexed foot)

dorsiflexion

depressing the foot

ex) pointing toes

plantar flexion

sole of foot turns medially

ex) stands on outside of foot

inversion

sole of foot turns laterally

eversion

forearm rotates laterally so palm faces anteriorly

ex) palms face back of body

supination

forearm rotates medially so palm faces posteriorly

ex) palms face forward

pronation

unique action where thumb touches tips of fingers on same hand

opposition

muscles can’t ___ only ___

push, pull

body movements results from

two or more muscles acting together or against each other

muscles are arranged in ____

groups

groups of muscles that produce opposite movements lie on

opposite sides of a joint

muscle that has major responsibility for causing a particular movement

prime mover

muscle that oppose or reverse a movement

antagonist whe

a prime mover is active the antagonist is

relaxed

antagonist can also be

prime movers

help prime movers by producing the same movement or reducing undesirable movement

ex) making a fist without bending the wrist, muscles stabilize wrist bones

synergists

specialized synergists, hold a bone still so tension ca move insertion bone

fixators

muscles named on ____, ____, or ________

criteria, structural, functional characteristics

7 ways to name muscles

1. direction of muscle fibers

2. size of muscle

3. location

4. number of origins

5. location of origin and insertion

6. shape of muscle

7. action of muscle

2 directions muscles can travel and what they mean

rectus- straight up and down

oblique- slanted

3 sizes of muscles and what they mean

maximus- large

minimus- small

longus- long

explain location

what bone the muscle covers

3 number of origin and what they mean

bi- two

tri- three

quad- four

explain location of origin and insertion

named for attachment site

3 actions of muscles

flexor

extensor

adductor

facial muscles are inserted into _____ or
___ and pull on ___ for _______

soft tissue, skin, skin, facial expressions

neck muscles move ___ and _____ and are usually ____ muscles

head, shoulder girdle, small

covers the frontal bone, raise eyebrows, wrinkles forehead

frontalis