muscle histology and cytology

muscle cells are called

fibers

myoblasts

muscle fiber stem cells

different muscle tissues are distinguished by

shape of muscle fibers and striations/lack of striations

striations

alternate dark and light bands found on skeletal and cardiac muscle

muscle tissue is mostly made up of

muscle fibers

muscle tissue is generally intermixed with

connective tissue

types of muscle

smooth, cardiac, skeletal

smooth muscle

appearance of smooth muscle fibers

non-striated, spindle shaped, single nucleus

what control does smooth muscle have

involuntary control

important organelles/cytoskeleton/junctions in smooth muscle

numerous gap junctions, actin and myosin placed in multiple planes

what are gap junctions used for

communication

why does smooth muscle line blood vessels

to maintain blood pressure, direct blood flow

why does smooth muscle line gastrointestinal/digestive tract

to move digested materials

cardiac muscle

appearance of cardiac muscle fibers

striated, cylindrical and branched, single nucleus

what control do cardiac muscles have

involuntary control

example of involuntary control in cardiac muscles

heart rate can't be controlled

important organelles/cytoskeleton/junctions in cardiac muscle

gap junctions, desmosomes, highly organized actin and myosin, mitochondria take up 20% of fiber volume

functions of cardiac muscle

To pump blood and maintain blood pressure

skeletal muscle

appearance of skeletal muscle fibers

striated, long cylinders, multiple nuclei (multinucleate)

what control does skeletal muscle have

voluntary control by motor neurons

important organelles/cytoskeleton/junctions in skeletal muscle

highly organized actin and myosin, mitochondria take up 2% of fiber volume, sarcoplasmic reticulum

function of skeletal muscle

movement, posture, joint stability, heat generation

important structures of the skeletal muscle fiber

sarcolemma, multinucleate, sarcoplasmic reticulum

general structure of skeletal muscle

long cylinders

sarcolemma

cell membrane of muscle fibers

parts of sarcolemma

motor end plate, transverse tubules ( T-tubules)

Motor end plate of sarcolemma

specialized region where motor neuron interacts with the muscle fiber, part of neuromuscular junction

structure of motor end plate

folds, acetylcholine receptors

transverse tubules (T-tubules) of sarcolemma

cylindrical indentation of sarcolemma

function of transverse tubules

brings action potential/electrical stimulus into the fiber's interior

multinucleate

many nuclei

why do muscles need a lot of nuclei

muscles have a lot of protein, nuclei have genetic material that encode for them

sarcoplasmic reticulum

located near ends of the transverse tubules

function of sarcoplasmic reticulum

stores calcium

important molecules for atp production

glycogen, myoglobin, creatine phosphate

myoglobin

protein only found in muscle

what kind of protein is myoglobin

globular protein

what kind of protein is actin

fibrous protein

globular protein function

functional

fibrous protein function

structural

what does myoglobin bind to

oxygen (O2)

why does myoglobin bind to oxygen

so it can be stored in muscle

Creatine Phosphate

storage form for ATP

is creatine phosphate quicker than producing ATP in the mitochondria?

yes

function of creatine phosphate

can donate a P to ADP, making ATP

major proteins

myofilaments, proteins associated with actin

types of myofilaments

thin filaments and thick filaments

thick filament

myosin

myosin structure

fibrous tails, globular heads

myosin tails

fibrous proteins bundled into a rope

myosin head

globular

what do globular and fibrous portions of myosin indicate

myosin is both structural and functional

thin filament

actin

what type of protein is actin

globular

actin structure

arranged into two long filaments wrapped around each other

proteins associated with actin

tropomyosin and troponin

what kind of protein is tropomyosin

fibrous

what kind of protein is troponin

globular

tropomyosin structure

thin filament wound around the actin

tropomyosin function

blocks actin-myosin binding sites

troponin structure

linked to tropomyosin

troponin function

calcium binding site

what happens when troponin is bind to?

it changes shape

sarcomere

functional unit of skeletal muscle fiber

what is sarcomere banding pattern determined by

myosin and actin

sarcomere function

gives striated appearance of muscle fibers

sarcomere location

between two Z lines

z line (z disc)

ends of sarcomeres

light band

split in half by a Z-line, one half sits in one muscle unit and the other half sits in the next

dark band

width defined by thick filaments

order of skeletal muscle gross anatomy

muscle fiber, fascicle, gross muscle

muscle fiber

muscle cells

fascicle (fasciculus)

group of muscle fibers

gross muscle

several fascicles

connective tissue sheaths

epimysium, perimysium, endomysium, fascia

composition of connective tissue sheaths

loose/areolar connective tissue, each layer is continuous/interconnected with the others

Endomysium

surrounds individual muscle fiber

Perimysium

surrounds a fascicle

what does perimysium contain

blood vessels and nerves run in perimysium in between fascicles

Epimysium

outer layer of connective tissue, surrounds all fascicles/muscle

epimysium also serves as

bone attachments (indirect and direct attachments)

Fascia

connective tissue that forms a sheet of tissue under the skin

what can fascia also surround

individual muscles or muscle groups