Unit 4 Lecture 22 Muscle Anatomy

Cardiac Muscle

Lots of striations

Involuntary control

Short, Branched

has intercalated discs between branches

Smooth Muscle

Found in bladder, uterus, stomach, digestive tracts, lining of blood vessels, bronchi

No striations

Spindle-shaped, stacked

Involuntary control

Skeletal Muscle

Attached to skeletons

Striations

long cylindrical

no branch

multiple nuclei

repairs by satellite cells

voluntary control

Tendons

Connect muscles to bones

Ligaments

Connect bones to other bones

Functions of Skeletal Muscle

Movement

Posture

Protection of soft tissue

Controls exits and entrances

Produce body heat

Controls blood glucose levels

Epipmysium

Dense outer layer of collagen

continuous with the tendon

Perimysium

layer within each muscle

divides muscle into compartments

Endomysium

thin connective tissue layer surrounding individual muscle fibers

Muscle

bundle of fascicles surrounded by epimysium

Fascicles

bundle of muscle fibers surrounded by perimysium

Fibers

muscle cells wrapped by endomysium

Parallel Elastic Component

Surrounds muscle and components

Parallel to the contractile parts of the muscle

Ex: Epimysium, Perimysium, Endomysium

Series Elastic Component

Joined ends with contractile parts

Ex: Tendons

Myoblasts

muscle fibers develop through the fusion of mesodermal cells

1 muscle cell= 100s of myoblasts

Myosatellite Cells

provides nourishment

helps repair any damage

Sarcolemma

cell membrane of a skeletal muscle

layer under endomysium

Transvers Tubules

pore openings up to the membrane

help with contraction

Sacroplasm

cytoplasm of the cell

contains glycogen (stores glucose)

Contains myoglobin (stores oxygen)

Sarcoplasmic Reticulum

ER of a muscle cell

stores Calcium

Myofibrils

length of the cell fibers

Myofilaments

thick and thin filaments

active portion of muscle contraction

Terminal Cisternae

forms network around each myofibril

forms a sac near T tubules

forms a triad

Thick filaments

myosin proteins orientated in the same direction

Golf Club:

Handle=myosin tail

Club= 2 myosin heads

Thin Filaments

Actin

G Actin= molecular subunits

F Actin= entire strand

Tropomyosin

Strands of protein that cover the active site of the G actin molecules

Troponin

Small protein attached to tropomyosin

moves when muscles try to contract

binds to calcium

Dystrophin

Linking proteins

Link actin to cell membrane

Strengthen contraction by pulling on sarcolemma

Muscle Dystrophy

Weak Muscles

Sarcomere

Repeating groups of thin and thick filaments

Z-Disc

ends of sarcomeres

attachment site for thin filaments

M-Line

Attachment for thick filaments

middle of sarcomere

H-Band

Only where thick filament is found

I-Band

Only where thin filament is found

Zone of Overlap

Region where thick and thin filaments meet