Muscle Flashcards
All cells are capable of some degree of movement, but some cells form multicellular contractile units called… drum roll..
muscles
what are the three types of muscles
skeletal, smooth and caridac
two words that describe skeletal muscle
striated, voluntary
two words that describe smooth muscle
non-striated, involuntary
two words that describe cardiac muscle
striated, involuntary
what are muscles surrounded by
an elastic lamina
what causes contractile forces to develop
contractile forces develop by internal contractile proteins transmitting forces to the external lamina via link proteins in the cell membrane
what is the skeletal muscle responsible for the movement of
responsible for the movement of the skeleton and organs like the tongue
why is the skeletal muscle referred to as voluntary
because it is capable of conscious control
what gives the appearance of striations in skeletal muscle
the arrangement of contractile proteins gives the appearance of cross-striations on light microscopy, so also called striated muscle
muscle is made up of highly specialised cells so what is the cytoplasm referred to, what is the endoplasmic reticulum referred to
cytoplasm - sarcoplasm, endoplasmic reticulum - sarcoplasmic reticulum, etc. plasma membrane - sarcolemma
what is skeletal muscle composed of in terms of cells
multinucleate contractile cells
what is skeletal muscle contraction mainly controlled by
the large motor nerve
what is a group of muscle fibres supplied by the same nerve called
a motor unit
when a nerve fires a motor unit, what happens
all the fibres in the motor unit contract simultaneously
what does the vitality of a skeletal muscle fibre depend on
the nerve supply, so if the supply is damaged, the muscle fibres atrophy
what are individual muscle fibres (cells) grouped together in
fasciculi
individual muscle fibres are grouped together in fasciculi with delicate supporting tissue called
endomysium
what is each fascicle surrounded by
a loose supporting tissue called perimysium
*label this diagram of muscle
there
a muscle involved in fine controlled movements such as controlling the eye has what sort of structure in terms of fasciculi and perimysium
small fasciucli and lots of perimysium
what do muscles involved in gross movements e,g. buttocks have in terms of fasciculi
large fasciculi
how would you describe the muscle fibres in skeletal muscle on a stained slide
each fibre is elongated, unbranched and cyclindrical
what is the nuclei of skeletal muscle fibres like
numerous flattened nuclei are located at regular intervals just underneath the plasma membrane (sacrolemma)
why are there cross striations seen in skeletal muscles
cross striations due to contractile proteins
what are the two contractile proteins
actin and myosin
in smooth muscle the arrangement of contractile proteins does not give the appearance of
cross striations
where can smooth muscle be found
the muscular component of visceral structures such as blood vessels, uterus, GI tract and bladder
under what control is smooth muscle
under inherent autonomic and hormonal control so called involuntary muscle
what type of contractions does smooth muscle take
specialises in continuous contraction of relatively low force producing diffuse wave like rhythmic movements
how does the contraction occur in terms of motor units in smooth muscle
in smooth muscle the whole muscle mass contracts rather than individual motor units
how would you describe the cells of smooth muscle under staining
cells relatively small, only a single nucleus. fibres are elongated spindle shaped cells with tapered ends. nucleus is centrally located
what is the myocardium
The myocardium is the muscular wall of the heart, or the heart muscle
what type of muscle makes up the myocardium
cardiac obvs
cardiac muscle is an intermediate between smooth and skeletal. Like skeletal muscle, contractions of cardiac muscle are
strong and utilise much energy
cardiac muscle in an intermediate between smooth and skeletal muscle, like smooth muscle, contractions are continuous and initiated by
inherent mechanisms - modulated by nerves and hormones
how would you describe cardiac muscle fibres
long and cylindrical, with one or two centrally placed nuclei
how would you describe the striations in cardiac muscle
arrangement of contractile proteins similar to skeletal muscle, striations less obvious as myofibrils and cells are more irregularly shaped
name a key feature to cardiac cells
they have intercalated discs - Cardiac muscle consists of individual heart muscle cells (cardiomyocytes) connected by intercalated discs to work as a single functional organ or syncytium.
contraction of myocardium occurs as a whole in each cardiac cycle, what is it co ordinated by
coordinated by highly modified cardiac cells - purkinje system
