muscle tissue - structure and function

Question 1

skeletal muscle

Answer 1

striated, myoglobin present, voluntary control and direct nerve-muscle communication

Question 2

cardiac muscle

Answer 2

striated, myoglobin present, involuntary control, indirect nerve-muscle communication

Question 3

smooth muscle

Answer 3

non-striated, myoglobin absent, involuntary control, no direct nerve-muscle communication

Question 4

what is myoglobin

Answer 4

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

Question 5

components of a muscle cell

Answer 5

sarcolemma - membrane 
sarcoplasm - cytoplasm 
sarcosome - mitochondrion 
sarcomere - contraction unit 
sarcoplasmic reticulum - ER of muscle cell

Question 6

structure of skeletal muscle and its function

Answer 6

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

Question 7

special feature of muscle fibres on tongue

Answer 7

muscle tissues is orientated in many different directions allowing for the mobility of the tongue

Question 8

thin fibres = and thick fibre =

Answer 8

thin = less blood and thick = more blood. this is shown by dark red gelatine being injected into an arterial supply

Question 9

DRAW structure of myofibril

Answer 9

z line, I bad ,h zone and a band, I band and z disc

Question 10

where are fast and slow twitch fibres found

Answer 10

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

Question 11

features of slow twitch

Answer 11

type 1 fibre
rich blood supply 
aerobic
high myoglobin 
many mitochondria 
many cytochromes
red in colour 
fatigue resistant

Question 12

features of fast twitch

Answer 12

type 2 A or B fibre 
poor blood supply 
anaerobic 
low myoglobin 
few mitochondria 
few cytochromes 
white colour 
rapidly fatigued

Question 13

what is a cytochromes

Answer 13

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.

Question 14

structure of cardiac muscle

Answer 14

striations, centrally portioned nuclei and intercalated discs. also has branching

Question 15

cardiac vs skeletal

Answer 15

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

Question 16

What is ANP and BNP

Answer 16

these are peptides related by the atria and ventricles during heart failure. they reduce arterial pressure by decreasing blood volume and vascular resistance

Question 17

what is hypertrophy

Answer 17

enlargement of individual cells

Question 18

what is hyperplasia

Answer 18

multiplication of cells

Question 19

atrophy and hypertrophy in heart?

Answer 19

H= larger heart than usual 
A= smaller heart than usual

Question 20

what are purkinje fibres

Answer 20

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

Question 21

how does the heart conduct

Answer 21

look it up

Question 22

features of smooth muscle

Answer 22

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

Question 23

where is smooth muscle found

Answer 23

in vascular structures in gut and respiratory tract

Question 24

what happens when smooth muscle develops a mind of its own

Answer 24

high blood pressure, asthma, abnormal gut movement, painful mensuration

Question 25

describe the structure of the smooth muscle of the gut

Answer 25

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

Question 26

muscle repair in skeletal muscle

Answer 26

cannot divide but regenerates by mitotic activity of satellite cells. hyperplasia follows after muscle injury and muscle mass increases

Question 27

muscle repair in cardiac muscle

Answer 27

incapable of regeneration. fibroblasts willl invade and lay down scar tissue

Question 28

muscle repair in smooth muscle

Answer 28

retain mitotic activity and can form new smooth muscle cells (shown when muscle wall becomes thicker during pregnancy)