Chapter 7

muscle tissue

consists of elongated muscle cells specialized for contraction

what are the three types of muscle tissue

skeletal, smooth, and cardiac

where are all types of muscle tissue derived from

the mesoderm

skeletal muscles are

organs

what does skeletal muscles have (composed of)

skeletal muscle tissue, connective tissue, nerves, and blood vessels

skeletal muscles can be directly or _______ attached to bone

indirectly

the muscular system includes about how many skeletal muscles

700

what are the functions of skeletal muscle

1. move the skeleton

2. maintain posture and body position

3. support soft tissues

4. guard entrances and exits

5. maintain body temperature

how do skeletal muscles move the skeleton

they pull on tendons that then move bones

_____ wall and _____ cavity floor are composed of skeletal muscles

abdominal, pelvic

skeletal muscles encircle openings of ____ and _____ tracts

digestive, urinary

muscle contractions generate

heat

each skeletal muscle cell is called a muscle ____

fiber

what are the 5 types of connective tissue in muscles

epimysium, perimysium, endomysium, tendons, and aponeurosis

epimysium

“outer muscle” covers the entire muscle

perimysium

divides the muscle into fascicles and contains blood vessels and nerves supplying fascicles

fascicles

bundles of muscle fibers

endomysium

covers each muscle fiber and ties fibers together

what does the endomysium contain

capillaries and nerve fibers

what forms all three layers of connective tissue that comes together at the end of the muscles?

collagen fibers

what does connective tissue come together to form at the ends of muscles?

tendons and aponeurosis

tendons

bundle of fibers; attaches muscle to bone

aponeurosis

broad sheet of fibers; connects muscles to each other

why is it necessary to have an extensive network of blood vessels in skeletal muscles?

to supply high energy use

skeletal muscles are under what type of control

voluntary control

what does it mean when skeletal muscles are under voluntary control

it requires stimulation by the central nervous system

how does the CNS stimulate skeletal muscles

axons run through connective tissue layers to innervate individual muscle fibers

muscles can be very long up to 60 cm is a feature of what type of muscle

skeletal muscle

what muscles have multinucleate fibers

skeletal muscle

skeletal muscles have a repeating pattern that gives them a striped or _______ appearance

striated

sarcolemma

muscle cell’s (which includes the cytosol and organelles) plasma membrane

the sarcolemma surrounds the _____ or cytoplasm

sarcoplasm

the sarcoplasm contains _____ that lead into a network of tubules called _____

openings, transvers/t-tubules

t tubules

allow electrical impulses from sarcoplasm to reach the cell’s interior

what allows for the unified contraction of an entire fiber

t tubules

myofibriils

cylinder-shaped structures running the length of a muscle fiber

there are _____ myofibrils in each muscle fiber

hundreds to thousands

what are myofibrils encircled by

t tubules

there are bundles of thick and ____ myofilaments their sliding causes muscle fibers to _____

thin, contract

what type of myofilaments don’t change in length

thick

sarcoplasmic reticulum

a specialized smooth ER that forms a network around each myofibril

terminal cisterna

expended portion of the sarcoplasmic reticulum on either side of t tubules

the terminal cisterna contains

high concentration of calcium ions

triad

combination of two terminal cisternae and one t tubule

sarcomeres

repeating functional untis of myofilaments

what are the smallest functional units of skeletal muscle fibers

sarcomeres

each myofibfril has about _____ sarcomeres end to end

10,000

how are sarcomeres arranged

thick and thin filaments together produces the banded/striated appearance of the fiber

thick filament

myosin

thin filament

actin

what are the two sarcomere lines

z and m lines

z line

marks the boundaries of each sarcomere

titin

strands of proetin that connect the z lines to thick fiaments to maintain aligment

mline

located in the center of each sarcomere and made of proteins that connect central portions of the thick filaments

what are the sarcomere bands

a, i, and h bands

a band

darker region containing thick filaments and zone of overlap (thick and thin filaments)

i band

lighter region containing thin filaments only, it also includes the z line

h band

when fiber is relaxed, contains only thick filaments, includes the m line

thin filaments

thin twisted strands of actin molecules

specific _____ ____ on actin interact with myosin

active sites

when at rest, the active sites in thin filaments are covered by what?

tropomyosin

tropomyosin

protein that prevents actin-myosin interactions

troponin

protein consisting of 3 globular subunits

tropomyosin strands held in position by _____

troponin