Muscle structure and function

Question 1

3 types of muscle tissue

Answer 1

skeletal, cardiac, smooth

Question 2

cardiac muscle

Answer 2

found in heart responsible for circulating blood, small cells, and very limited ability to repair, involuntary contraction,s single nucleus in a cardiac muscle cell

Question 3

skeletal muscle

Answer 3

multinucleated, larger muscle, very large muscle cells (up to 30cm), partially repair, under voluntary control

Question 4

smooth muscle

Answer 4

found in walls of organs, single nucleus, can divide and repair itself if damaged, involuntary

Question 5

3 layers of muscle connective tissue

Answer 5

epimysium (round the entire muscle), perimysium (divides the muscle into small bundles- fasciculus), endomysium (around an individual cell)

Question 6

what is a muscle cell also known as

Answer 6

a muscle fiber

Question 7

functions of muscle tissue

Answer 7

produce body movement, stabilizes body position, regulates organ volumes, movement of substances in the body, produce hear

Question 8

how do muscles regulate organ volumes

Answer 8

bands of smooth muscles called sphincters control this

Question 9

how do muscle tissues produce heat

Answer 9

involuntary contractions of skeletal muscle (shivering)

Question 10

productions of muscle tissue

Answer 10

excitability, conductivity, contractility, extensibility, elasticity

Question 11

productions of muscle tissue- excitability

Answer 11

response to chemicals released from nerve cells

Question 12

productions of muscle tissue- conductivity

Answer 12

ability to propagate electrical signals over membrane

Question 13

productions of muscle tissue- contractility

Answer 13

ability to shorten and produce force

Question 14

productions of muscle tissue- elasticity

Answer 14

ability to return to original shape after being stretched

Question 15

Skeletal muscle tissue- attachment

Answer 15

attaches to bone, skin or facia (the skeletal system), maybe via tendons/ aponeuroses)

Question 16

Skeletal muscle tissue- striations

Answer 16

striated with light and dark bands visible with scope (due to proteins in muscle cells)

Question 17

Skeletal muscle tissue- multinucleated

Answer 17

due to development muscles are formed by multiple myoblasts that don’t fuse, these then become the satellite cells- stem cells, when damage to muscle they can divide and assist repair

Question 18

functions of skeletal muscle

Answer 18

produce skeletal movement, maintain body position, support soft/ hard tissue, guard body openings (sphincters), maintain body temp, stores nutrients reserves, role in proprioception

Question 19

skeletal muscle structures

Answer 19

connective tissues, nerves, blood vessels, muscle tissue

Question 20

Connective tissue layers- epimysium

Answer 20

outer layer- surround the whole muscle, exterior collagen layer, connected deep to fascia, separates muscle from surrounding tissues, fibrous irregular connective tissue

Question 21

Connective tissue layers- perimysium

Answer 21

middle layer- surrounds muscle fibre bundles (fascicles), contains blood vessels and nerve supply to fascicles, made of more elastic fibres (half collagen and half elastin)

Question 22

Connective tissue layers- endomysium

Answer 22

inner layer- surrounds individual muscle cells (muscle fibres), contains capillaries and nerve fibres contracting muscle cells, contains satellite cells that repair damage, more elastic fibres

Question 23

when do endomysium, perimysium and epimysium come together

Answer 23

at ends of muscles, to form connective tissue attachment to bone matrix e.g. tendon

Question 24

Skeletal muscle structures- nerve

Answer 24

skeletal muscles are voluntary muscles controlled by nerves of the central nervous system, peripheral nerves, a collection of muscle cells is supplied by a motor neurone (muscle nerve), each muscle cell is supplied by a terminal branch of motor neurone

Question 25

The sarcolemma

Answer 25

the cell membrane of a muscle cell, surrounds the sarcoplasm (cytoplasm of muscle), sarcoplasm is filled with tiny threads called myofibrils, and myoglobin (oxygen binding protein), a change in transmembrane potential begins contraction

Question 26

transverse T- tubules

Answer 26

they are invaginations of the sarcolemma into the centre of the cell, filled with extracellular fluid, carry muscle action potentials down into cell, allow the entire muscle fibre to contract simultaneously

Question 27

transverse T- tubules- mitochondria

Answer 27

they lie in rows throughout the cell, near the muscle proteins that use ATP during contraction

Question 28

What is a motor unit

Answer 28

one motor nerve and the muscle fibre it supplies

Question 29

skeletal muscle fibres

Answer 29

are long and cylindrical, develop through fusion of mesodermal cells (myoblast), become very large, contains hundreds of nuclei, nuclei arranged around periphery of cell, contains many mitochondria- lots of energy

Question 30

Skeletal muscle structures- blood vessels

Answer 30

each muscle cell is in contact with 1 or.2 capillaries, nerve fibres and capillaries are found in the endomysium between individual cells, need large blood supply- lots of energy

Question 31

why do muscles have extensive vascular systems

Answer 31

supply large amounts of oxygen, supply nutrients, carry away waste products

Question 32

what is a sarcoplasmic reticulum (SR)

Answer 32

a membranous structure surrounding myofibrils, systems of tubular sacs similar to smooth endoplasmic reticulum in non- muscle cell, forms chambers at each end (terminal cisternae), attached to T- tubules

Question 33

role of sarcoplasmic reticulum

Answer 33

helps to transmit action potentials to the myofibril, stores calcium ion

Question 34

when is a triad forms

Answer 34

it is formed by 1 T- tubercle and 2 terminal cisternae

Question 35

what do terminal cisternae do

Answer 35

concentrate Ca+ (via ion pumps) | release Ca++ into sarcomeres begin muscle contractions

Question 36

myofibrils and myofilaments

Answer 36

muscle fibres are filled with threads called myofibrils separated by SR, myofibrils are made up of bundles of protein filaments= myofilaments, myofilaments (thick and thin filaments) are the contractile proteins of muscles

Question 37

myofilaments and the sarcomere- I band

Answer 37

contains only thin filaments (actin), appears light

Question 38

myofilaments and the sarcomere- A band

Answer 38

contains thick (Myosin) and thin filaments

Question 39

myofilaments and the sarcomere- overlap reigion

Answer 39

in the overlap region of the A band, 6 thin filaments surround each thick filament- zone of overlap

Question 40

myofilaments and the sarcomere- filaments compartment

Answer 40

filaments are arranged in compartments= sarcomeres, separated by Z discs

Question 41

myofilaments and the sarcomere- M lie

Answer 41

myosin thick filaments attach to the M line

Question 42

myofilaments and the sarcomere- Z line/ discs

Answer 42

shaped like a Z, actin attaches here

Question 43

what is titin

Answer 43

titin is a muscle protein that is important in eccentric muscle contraction- attaches myosin filament to M line- helps muscles return to normal size and shape

Question 44

what is sarcomere

Answer 44

contractile unit of muscle, structural units of myofibrils, forms visible striated patterns within myofibrils, transverse tubules encircle sarcomeres near zones of overlap, Ca++ released by the SR causes thin and thick filaments to interact