24 terms

A&P 1 CH-9 muscle structure

Muscular System-Muscular structure
3 Types of Muscles
Skeletal, Smooth, Cardiac
Skeletal Muscle
Attached to bone, voluntary muscle, cells shaped like cylinders or tubes, striated.
Function: movement, posture, support joints, producing heat.
Smooth Muscle
Walls of organs (visceral) involuntary muscle, non-striated, digestive system, respiratory system.
Cardiac Muscle
Heart muscle only, involuntary, striated muscle, cells are long branching and fit tightly together to promote rapid conduction of electronic signals thoughout the heart.
Function: Pump Blood
Belly of the muscle
enlarged fleshy body of the muscle between the slender points of attachment. Composed of thousands of muscle fibers (muscle cells).
muscle fibers
muscle cells
surrounds the skeletal muscles, tough connective tissue.
outer layer of fascia
The fascia that extends toward and attaches to the bone, a strong cord-like structure.
layer of connective tissue that surrounds the fascicles (smaller bundles of muscle fibers).
small bundle of muscle fibers
Individual muscle fibers are found within the fascicles and are surrounded by a third layer of connective tissue.
3 ways of muscle attachment
Tendon attaches to the bone
Muscle attaches to the bone or soft tissue directly (without a tendon)
A flat sheet-like fascia (aponeurosis) connects muscle to muscle or muscle to bone
Muscle cell
an enlongated muscle fiber, has more than one nucleus and is surrounded by a thin cell membrane called the sarcolemma
Transverse Tubules -T Tubules
at several points the cell membrane penetrates deep into the interior of the muscle fiber. Cuts though
Sarcoplasmic Reticulum
within the muscle fiber, specialized endoplasmic reticulum, a layer underneath sarcolemma houses calcium.
Where Calcium is stored, when muscle is relaxed.
Each muscle fiber is composed of long cylindrical structures, consist of sarcomeres.
each myofibril is made up of a series of contractile units that extend from z-line to z-line, formed by a unique arrangements of two contractile proteins called actin and myosin.
actin filaments
thin, extend toward the center of the sarcomere from the z lines inside of sarcomere, contractile protein
Myosin Filaments
thicker, sits between the actin filaments, have myosin heads-contractile protein
Myosin Heads
structures extending from the myosin filaments
Muscle Contraction-sliding filament theory
Muscles can only pull, not push.
To contract the muscle must shorten.
The sarcomeres shorten due to the actin and myosin filaments sliding past each other to form crossbridges.
Need calcium and ATP to contract.
Form when stimulated.
The myosin heads make contact with the actin, forming temporary connections
muscle relaxation
Occurs when the crossbridges are broken, and the actin and myosin return to their original position. Uses ATP to break the crossbridge. Calcium returns to the sarcoplasmic reticulum (SR).