the muscular system Flashcards
how much of our total body weight is skeletal muscle
40-50%
skeletal muscle is primarily attached to what
bones, as involved in movement
is skeletal muscles movement voluntary or involuntary
Voluntary – we have cotious control over its movement
name the appearance of skeletal muscle
Striated appearance
whats the main function of skeletal muscle
Movement of bone & body parts
hows skeletal muscle involved in stabilizing
Stabilizing of body positions such as posture etc.
name the appearance of cardiac muscle
Striated appearance – histological composition of muscle produces this striped appearance
where is cardiac muscle found
Only found in heart
is cardiac muscle voluntary or involuntary
Involuntary – automimic regulation controls its contraction and relaxation
what is cardiac muscles function important for
Develops pressure for arterial blood flow to tissues to supply oxygen
is smooth/ visceral muscle voluntary or involuntary
Involuntary – so unconscious control
name the appearance of smooth/visceral muscle
Non-striated - no highly organized functional unit appearance, and non striped appearance
how is smooth/visceral muscle grouped
in walls of hollow organs
whats the function of sphincters in smooth/visceral muscle
Sphincters regulate flow in organs/vessels
whats the main function of smooth/visceral muscle
to Maintain diameter/function of organs/vessels
what happens when smooth/visceral muscle contact
they Move material in GI, urinary & reproductive tracts
what are the functions of muscles
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
name the 3 types of mucle
cardiac
smooth/visceral
skeletal
name where skeletal muscle is found
Muscle includes: muscle fibres, connective tissue, nerves & blood vessels
describe how skeletal muscle tissue is arranged
Entire muscle wrapped in Epimysium
Perimysium surrounds fibre bundles called fascicles
Endomysium surrounds each individual fibre
skeletal muscle tissue is well supplied with what and how come
with blood vessels and nerves
theres a Terminal of a neuron on each muscle fibre
what do tendons do, in terms of for muscles
Tendon attaches muscles to the bone
name and describe 3 of the important parts in skeletal muscle
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)
explain some muscle histology
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
why is muscles highly organised structure important
structure is essential for its function
explain the sarcomere
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
describe the zone and banding organisation within the Sarcomere zone
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
explain what the thick filament is composed of
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
explain the thin filament portion in muscle
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
explain the functional structure of muscle
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
in muscle contractions what happens to the sarcomere
The sarcomere shortens as the actin fibres slides over the myosin fibres
what happens during The Sliding Filament Mechanism of Muscle Contraction
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.
