Powerpoint on Muscles

8/11/2019 Powerpoint on Muscles

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The

MuscularSystem


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Smooth Muscle Cardiac Muscle Skeletal Musc

Found in walls of holloworgans. Functions to move

them.

Pump heartAttach to skele

Movement and po

non striatedstriated(striped)

striated

Involuntary & rhythmic Involuntary & rhythmic Voluntary (except r

Single nucleus Single nucleusCells are long with

nuclei

I. Types of muscle


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Smooth Muscle

Rhythmic contractions are calledPERISTALSIS.

II. Anatomy of skeletal muscle and musclecontraction

A. Fused cells form a sarcomere (theaction unit)

B. Sarcomeres are made up ofACTIN and MYOSIN filamentproteins.


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C. Myosin (thick) and actin (thin) overlap (castriations) and slide past each other to causcontraction.

1. Muscle contraction occurs when a moto

neuron (nerve cell) stimulates a skeletal mand causes the release ofNEUROTRANSMITTERS from sacs in thAXON TERMINAL. They diffuse across SYNAPTIC CLEFT and bind with receptorthe neighboring muscle cell - causing myoslide along actin.


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CalciumTroponin

Tropomyosin

Actin

Myosin

III. Sliding filament theory

A. Without calcium - Myosin cannoalong actin because binding sites acovered by chain. Troponin = lockTropomyosin = chain


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Calcium binds to troponin causing itto unlock. Tropomyosin slides down

Binding sites exposed. Myosinwalks along actin - muscle

contracts

E f


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IV. Energy for contractionA. Cellular respiration

makes ATP (and givesoff heat). Stage 1: Glycolysis (no O2needed) Stage 2: Citric acid cycle (O2

needed) Stage 3: Electron transport chain(O2 needed)

1. Blood supplies oxygen needed during citric acid cycle.

2. MYOGLOBIN (found in muscles) stores oxygen.

B When oxy en runs out durin strenuous activity lycolysis is used to m


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B. When oxygen runs out during strenuous activity, glycolysis is used to m

1.Less ATP is released

C. Energy sources for contraction CREATINE PHOSPHATE can regenerafrom ADP (10 sec.).

1. Toxic PYRUVATE molecules are converted into lactic acid.

2. LACTIC ACID builds up in the muscles (before diffusing into bloo

causes muscle soreness.

V Muscular responses


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V. Muscular responses

A. THRESHOLD STIMULUS - The minimum stimulus required to causecontraction (called a twitch) .

B. Each twitch has both a period of

contraction and relaxation.1. The LATENT PERIOD describes thetime between two muscle twitches.

2. The REFRACTORY PERIOD is theamount of time when a muscle fiber is

unresponsive.

Powerpoint on Muscles

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