the muscular system

Question 1

how much of our total body weight is skeletal muscle

Answer 1

40-50%

Question 2

skeletal muscle is primarily attached to what

Answer 2

bones, as involved in movement

Question 3

is skeletal muscles movement voluntary or involuntary

Answer 3

Voluntary – we have cotious control over its movement

Question 4

name the appearance of skeletal muscle

Answer 4

Striated appearance

Question 5

whats the main function of skeletal muscle

Answer 5

Movement of bone & body parts

Question 6

hows skeletal muscle involved in stabilizing

Answer 6

Stabilizing of body positions such as posture etc.

Question 7

name the appearance of cardiac muscle

Answer 7

Striated appearance – histological composition of muscle produces this striped appearance

Question 8

where is cardiac muscle found

Answer 8

Only found in heart

Question 9

is cardiac muscle voluntary or involuntary

Answer 9

Involuntary – automimic regulation controls its contraction and relaxation

Question 10

what is cardiac muscles function important for

Answer 10

Develops pressure for arterial blood flow to tissues to supply oxygen

Question 11

is smooth/ visceral muscle voluntary or involuntary

Answer 11

Involuntary – so unconscious control

Question 12

name the appearance of smooth/visceral muscle

Answer 12

Non-striated - no highly organized functional unit appearance, and non striped appearance

Question 13

how is smooth/visceral muscle grouped

Answer 13

in walls of hollow organs

Question 14

whats the function of sphincters in smooth/visceral muscle

Answer 14

Sphincters regulate flow in organs/vessels

Question 15

whats the main function of smooth/visceral muscle

Answer 15

to Maintain diameter/function of organs/vessels

Question 16

what happens when smooth/visceral muscle contact

Answer 16

they Move material in GI, urinary & reproductive tracts

Question 17

what are the functions of muscles

Answer 17

Production of body movements

Stabilisation of body positions - posture

Regulation of organ volume

Movement of substances internally via contactions

Production of heat from its contractions

Question 18

name the 3 types of mucle

Answer 18

cardiac

smooth/visceral

skeletal

Question 19

name where skeletal muscle is found

Answer 19

Muscle includes: muscle fibres, connective tissue, nerves & blood vessels

Question 20

describe how skeletal muscle tissue is arranged

Answer 20

Entire muscle wrapped in Epimysium

Perimysium surrounds fibre bundles called fascicles

Endomysium surrounds each individual fibre

Question 21

skeletal muscle tissue is well supplied with what and how come

Answer 21

with blood vessels and nerves

theres a Terminal of a neuron on each muscle fibre

Question 22

what do tendons do, in terms of for muscles

Answer 22

Tendon attaches muscles to the bone

Question 23

name and describe 3 of the important parts in skeletal muscle

Answer 23

Epimysium –encloses entire muscle (its the largest)

Perimysium – encloses fibre bundles (fascicles - these are surrounded by endomysium)

Endomysium – encloses each fibre (fibre units are the smallest unit)

Question 24

explain some muscle histology

Answer 24

elongated cylindrical cells = muscle fibres
(The cells are cylindrical in shape creating long fibres, so is why the mule cells are often referred to as muscle fibres)

Sarcolemma =
plasma membrane

Transverse (T- tubules) membrane extensions from surface to centre of each fibre
(Muscles fibres can communicate via these transverse)

Sarcoplasm = similar to Cytoplasm – contains myoglobin which is related to Haemoglobin - carries oxygen
(Sarcomeres are crucial for contraction)

Multiple nuclei lie near surface within the muscle cells

sarcoplasmic reticulum = equivalent of endoplasmic reticulum in other cell types
- It Stores Calcium ions

Along entire length of cell are myofibrils

Myofibrils made of protein filaments which contain:
- thick (myosin) and
- thin (actin) filaments

Question 25

why is muscles highly organised structure important

Answer 25

structure is essential for its function

Question 26

explain the sarcomere

Answer 26

This structure allows the cell to contact

Actin & Myosin filaments overlap in repeating patterns

Unit structure is called sarcomere

Separated by Z-discs

Darker area = A-band associated with thick filaments

H-zone has no thin filaments

I-band has thin filaments and no thick filaments as less myosin in that area

Question 27

describe the zone and banding organisation within the Sarcomere zone

Answer 27

H zone is in middle , Next is A band and then I bands

The thin filaments move over the thick filaments and bring the discs closer to one another which brings about the muscle fibres contraction when a nervous impulse instructs it to do so

Question 28

explain what the thick filament is composed of

Answer 28

of myosin protein, which has a motor function due to its head moving when ATP is present and is cleaved, causing movement of actin on the top of the myosin protein

Question 29

explain the thin filament portion in muscle

Answer 29

Actin is a family of globular proteins with many functions

the troponin complex has 3 regulatory proteins that are integral to not only skeletal but also cardiac muscle contractions

Tropomyosin is 2 stranded alpha helical coil protein often found in inter skeletons.

Actin itself has a myosin binding site, so myosin of thick filament is able to bind

Question 30

explain the functional structure of muscle

Answer 30

Thick filament (myosin) has moveable heads

Thin filaments (primarily composed of actin) are anchored to Z-discs
- Contain myosin binding sites for myosin head
- Also contain tropomyosin & troponin

Tropomyosin has regulatory function as can blocks myosin binding site at rest

Question 31

in muscle contractions what happens to the sarcomere

Answer 31

The sarcomere shortens as the actin fibres slides over the myosin fibres

Question 32

what happens during The Sliding Filament Mechanism of Muscle Contraction

Answer 32

During contraction myosin heads bind to actin sites

Pull and slide actin molecules (and Z-discs) toward H-zone

I-bands and H-zones narrow

This Sliding generates force and shortens sarcomeres and thus fibres.