Human Anatomy and Physiology-Chapter 6:Muscular System Notes

I.Overview of Muscle Tissues Differ in cell structure,location, and how they are stimulated to

contract Smooth and skeletal muscle cells are elongated and called

________________________ Contraction-shortening-depends on 2 types of myofilaments Terms myo-,sarco- and mys- refers to muscle-example-muscular

cytoplasm is called ___________________.A. skeletal muscle

attach to skeleton and form smoother contours of body huge,cigar shaped and ______________________ largest of muscle fibers-as much as 30 cm in length __________________________with obvious stripes ______________________________since only muscle subject to conscious

control However,subject to involuntary reflexes Tire easily and requires rest Fairly fragile Bound by ___________________________which provides strength and

support Each muscle fiber contained in a declicate connective tissue sheath called

___________________________ _________________________-connective tissue wrapping a bundle of

fibers called a _________________ ___________________________= many fascicle bound together w/ this

tough coat Epimysia blend into the strong_,cordlike_________ or aponeurose that

connect muscle to bones,cartilages or connective tissue Other functions of tendons-besides movement-are durability and

conservation of space

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B. Smooth Muscle No striations and is involuntary Mainly in walls of hallow visceral organs such as

____________________________________________________________________________________

Propel substances on a definite tract or pathway Spindle shaped and uninucleate Scant endomysium Most often in 2 layers-one running circularily and one running

longitudinally-alternately contract or relaxing changing size and shape of organ

C. Cardiac Muscle

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Only in heart Forms most of heart walls ________________________but involuntary Cushioned in bundles w/ small amount of endomysium When heart contracts,internal chambers get smaller,forcing

blood into arteries leaving heart Branching cells joined by junctions-

___________________________________These traits and spiral arrangement of bundles allow heart activity to be closely coordinated,giving steady contraction rate

______________________can shift heart into “high gear”****** We focus mostly on skeletal muscle here!

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D. Muscle Functions1. _______________________as a result of muscle

contraction;quick response to environment2. Maintaining _____________-maintain erect posture despite

gravity3. Stabilizing ________________-esp. w/ poorly fitting

articulating surfaces as in shoulder4. _________________________________-by –product of

muscle activity;ATP used for contractions and ~40% released as heat to mostly maintain normal body temp for at least 40% of body mass

II. Microscopic Anatomy of Skeletal Muscle

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a. ________________________ = plasma membrane of muscle cells

b. Nuclei pushed aside by ________________-long ribbonlike organelles;have alternating light (I) and dark (D) bands along myofibrils-give striped appearance

c. I band has midline interruption - darker__________________

d. A band has lighter central area called _____________-Its M line contains tiny protein rods that hold thick filaments together

e. Myofibril actually chains of contractile units-_____________________-line up end –to- end along myofibril length

f. 2 type of protein myofilaments-larger is ___________________ made of bundled myosin

–extend length of A bandg. Also contain ATP enzymes to generate ATP or

energy-h. Ends studded w/ small projections-

____________________________i. Thin filaments composed of ______________-called

actin filaments-anchored to z disc-do not extend into end of relaxed sarcomere,so central region-_________________is sometimes called bare zone

j. In a contraction,bare zone does not appear because actin and myosin completely overlapped

k. ______________________________(SR)-specialized smooth ER-tubules and sacs surround every myofibril-picture a crocheted sleeve-Role is to__________________________________________________________________________

III. Skeletal Muscle ActivityA. Stimulation and Contraction of Single Muscle Cells

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Functional properties include 1)___________________(irritability/responsiveness)-ability to receive and respond to stimulus2) _______________________-ability to forcibly shorten when stimulated3) _________________________-ability of muscle cells to stretch4)__________________________-ability to recoil and resume resting length

Nerve stimulus and Action Potential: Must receive nerve stimulus May be a few or 100’s of muscles cells stimulated by a nerve

cell______________________ _____________________= 1 neuron and all skeletal muscles

stimulated __________-long extension of nerve cell-branches into axon

terminals when it reaches muscle,each forming a junction w/sarcolemma=_________________junctions

Nerve and muscle are close but do not totally meet-forming ____________________(has interstitial fluid)

When nerve impulse reaches terminals-___________________________is released-Ach-________________________in the case of skeletal muscles

AAh attaches to receptors(membrane proteins)part of sarcolemma.With enough Ach ,sarcolemma is more permeable to Na+ that diffuse out of cell….more Na enters than K+ leaves----creates a current called ___________________________-now unstoppable-result in muscle contraction

Ach is broken down into ____________________________by enzymes acetylcholinesterase-AChE-during action potential,so one impulse makes one contraction

Returns to resting state by…1. diffusion of ___________out of cell2. operations of ________________pumping NA+ and K+ ions back to

original position

B. Mechanism of Muscle Contraction _________________________TheoryWhen muscle fibers

are activated by nervous system,myosin heads attach to binding sites on thin filaments and sliding begins.Each cross bridge attach and detach several times during a contraction-pulling filaments towards center of sacromere and cell shortens

The movement of myosin cross bridges is somewhat like that of a centipede

The attachment of myosin cross bridges to actin requires Ca2+ ions,which come from inside the cell where action potentials stimulate sarcoplasmic retuiculum to release Ca2+

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into cytoplasm.this triggers the binding of myosin to actin causing filaments sliding

When action potential ends,Ca2+ ions are reabsorbed into SR storage areas and muscle cell relaxes

C. Contraction of skeletal muscles as a whole Whole muscle responds to “all or none principle”,but whole

muscle reacts in _____________________ Can be changed by ________________________of muscle

stimulation and by changing # muscle fibers stimulated ____________________________=brief jerky contractions Normally,nerve impulses are delivered at a very fast rate w/o

much relaxation Smooth,rapid sustained contractions called _____________or

complete,tetanus Until complete tetanus is reached,the muscle is said to be

______________________________tetanus Muscle contractions can be slight or vigorous depending on

work to be done and thus innervation Energy for muscle contractions-needs to make ATP:

1. Direct phosphorylation of ADP by creatine phosphate(CP)-found in ____________________but not other cell types.As ATP is used,reactions between CP and ADP generates more ATP.(CP supply quickly exhausted

2. _____________________-for light to moderate exercise,95% ATP comes from aerobic-cellular respiration-from mitochondrion….the collection of chemical pathways are also called ____________________________________.Glucose broken down to CO2 and H2O 36 ATP/1 g glucose-fairly slow and requires continuous O2.

3. _________________________________________________________________________- occurs to provide pyruvic acid fro cell respiration---occuring in cytosol.After this ,w/o O2,fermentation via production of _______________________occurs-5% of ATP from each glucose-promotes muscle fatigue and soreness

___________________________occurs if muscle is unable to contract even though it is still innervated…usually caused from ___________________________________________ during prolonged muscle activity….alot dependent on muscle supply….breathing rapidly and deeply will generate more ATP

Types of Muscle contractions:1. ________________________________-myofilaments are

successful in sliding movements,muscle shortens and causes movement-eg. Knee bending

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2. _______________________________________-myosin myofilaments are “spinning their wheels”and tensions continually increases -trying to slide but you are attempting to move something immovable

____________________________--state of continuous partial contraction-firm and ready for action

____________________- muscle is not innervated and becomes soft and flabby

___________wasting away of a muscle Aerobic –or endurance-exercise-results in stronger,more flexible muscles

and subjected to less fatigue(jogging,biking)-results partly because of greater blood supply-also enhances metabolism in general-improving digestion,elimination,coordination and cardiovascular system………..but does not increase muscle size mush

Resistance –or ______________________exercises increases muscle size-increase individual muscle cell size(make more contractile filaments and increases connective tissue)

IV.Muscle Movements,Types and names

A. Types of Body Movement

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Every one of our 660+skeletal muscles is attached to bone or other connective tissue at no fewer than 2 points:

1. ____________attached to immovable or less movable bone

2. ______________attached to more movable bone Muscle moves toward origin in contraction Most common movements:

1. ___________________movement mainly in sagittal plane that decreases < of joint and brings 2 bones closer together-eg.knee and elbow

2. ____________________opposite of flexion and increases >-eg straightening knee

3. ________________________movement of bone around longitudinal axis-eg in ball- and- socket joints

4. __________________________-moving limb away from midline

5. ___________________________opposite of abduction-toward bodyline

6. ___________________________-combination of flexion,extension,abduction,adduction commonly seen in ball-and socket-proximal end of limb is stationary,and its distal end moves in a circle-outlines a cone

B.Special Movements1. ____________________________-Up and Down movement of foot at ankle:pulled

toward shin is dorsiflexion and pointing towards toe is plantar flexion2. _____________________________invert turn sole medially and evert,turn sole

laterally3. ___________________________________-supination-turn backwards @ radius and

ulna-forearm rotates laterally to turn palm anterior laterally-radius and ulna parallel/pronation when forearm rotates medially-palm faces posterior-radius and ulna form X.

4. ___________________________-opposition from saddle joint in hand-moves ththumb to touch other fingers

C. Interactions of Skeletal Muscles in the Body Muscles can only pull ____________________________-major muscle responsible for designated

movement _________________________ -oppose or reverse a movement __________________________-help prime movers by doing same movement

or reducing undesirable movement-example:making a fist w/o moving wrist Fixators-specialized synergists-hold a bone still or stabilize origin of prime

mover so all tension used to move insertion boneD. Naming skeletal muscles

1. Direction of muscle fibers-in re to an imaginary line-example-rectus(straight)-rectus femoris-straight muscle of thigh

2. _____________________________________-maximus,minimus,longus

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3. location of muscle-associated bone used in name often eg-temporalis muscle overlies temporal bone

4. _____________________________________-eg. Biceps-2 origins5. Location of muscle’s origin and insertion-eg.sternocleidomatstoid-origin

in sternum and clavicle-inserts in mastoid process of temporal bone6. _________________________________-eg.deltoid means triangular7. _________________________________-eg-flexor

E. Arrangement of Fascicles1. ________________-fascicles in concentric circles(spinchters)2. __________________-meet at a single insertion-triangular or fan shaped3. ________________________-parallel to long axis of muscle4. __________________________-spindle –shaped muscle w/expanded center(biceps

brachii)5. _____________________-short fascicles attach obliquely to a central tendonV.MAJOR MUSCLES TO REMEMBER

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