muscle tissue - structure and function Flashcards
skeletal muscle
striated, myoglobin present, voluntary control and direct nerve-muscle communication
cardiac muscle
striated, myoglobin present, involuntary control, indirect nerve-muscle communication
smooth muscle
non-striated, myoglobin absent, involuntary control, no direct nerve-muscle communication
what is myoglobin
protein very structurally similar to haemoglobin providing oxygen to working muscle. Haemoglobin will give up oxygen to myoglobin when pH is v low. when muscle is damaged it will cause myoglobin to be relased
components of a muscle cell
sarcolemma - membrane sarcoplasm - cytoplasm sarcosome - mitochondrion sarcomere - contraction unit sarcoplasmic reticulum - ER of muscle cell
structure of skeletal muscle and its function
epimysium - outer layer around cluster of fascicles
perimysium - layer around fascicle
endomysium - layer around muscle fibre within fascicle
The skeletal muscle is joined to tendons which connect it to bone at the point of origin(part that doesn’t move) and insertion(does move during contraction). if these cross a joint it moves and the direction of this movement is dependant on the direction of the muscle fibres
special feature of muscle fibres on tongue
muscle tissues is orientated in many different directions allowing for the mobility of the tongue
thin fibres = and thick fibre =
thin = less blood and thick = more blood. this is shown by dark red gelatine being injected into an arterial supply
DRAW structure of myofibril
z line, I bad ,h zone and a band, I band and z disc
where are fast and slow twitch fibres found
long distance = mainly slow twitch fibres
middle distance = mixture of slow and fast
short distance = mainly fast twitch
at-least one of each in each fascicle
features of slow twitch
type 1 fibre rich blood supply aerobic high myoglobin many mitochondria many cytochromes red in colour fatigue resistant
features of fast twitch
type 2 A or B fibre poor blood supply anaerobic low myoglobin few mitochondria few cytochromes white colour rapidly fatigued
what is a cytochromes
any of a number of compounds consisting of haem bonded to a protein. Cytochromes function as electron transfer agents in many metabolic pathways, especially cellular respiration.
structure of cardiac muscle
striations, centrally portioned nuclei and intercalated discs. also has branching
cardiac vs skeletal
both striated and have similar contraction mechanisms
BUT
nuclei are central and not peripheral in cardiac, there are no T tubules and only one contractile cell types which is the cardiomyocytes which communicated with other cells via the intercalated disc gap junctions
What is ANP and BNP
these are peptides related by the atria and ventricles during heart failure. they reduce arterial pressure by decreasing blood volume and vascular resistance
what is hypertrophy
enlargement of individual cells
what is hyperplasia
multiplication of cells
atrophy and hypertrophy in heart?
H= larger heart than usual A= smaller heart than usual
what are purkinje fibres
conduct an action potentail v rapidly enabling ventricles to contract in synchronisation. They are cells with abundant glycogen, sparse myofibrils and extensive gap junction sites
how does the heart conduct
look it up
features of smooth muscle
spindle shaped with single central large nucleus. they are non striated, no sarcomeres or t tubules and capable of being stretched. contraction is slower and more sustained and response to never signals, hormones, drugs or blood gases
where is smooth muscle found
in vascular structures in gut and respiratory tract
what happens when smooth muscle develops a mind of its own
high blood pressure, asthma, abnormal gut movement, painful mensuration
describe the structure of the smooth muscle of the gut
has a longitudinal layer of smooth muscle and a circular layer attached to a mucosal membrane with protrusions and vili to increased the surface area
muscle repair in skeletal muscle
cannot divide but regenerates by mitotic activity of satellite cells. hyperplasia follows after muscle injury and muscle mass increases
muscle repair in cardiac muscle
incapable of regeneration. fibroblasts willl invade and lay down scar tissue
muscle repair in smooth muscle
retain mitotic activity and can form new smooth muscle cells (shown when muscle wall becomes thicker during pregnancy)
