Muscles Flashcards
Tendons are…
They join ___ to ___
Tendons are strong, fibrous connective tissue
They join muscle to bone
Ligaments join ___ to ___, in joints especially
Ligaments join bone to bone, in joints especially
State three types of muscle
Skeletal, smooth, cardiac
Describe skeletal muscle
3 points
a) Striated, tubular, multinucleated fibres
b) Attached to skeleton
c) Voluntary, we control it
Describe smooth muscle
2 points
a) Involuntary, non-striated, uninucleate
b) Lines the walls of internal organs
Describe cardiac muscle
1 long point
a) Involuntary, uninucleate, striated, branched, myogenic
In skeletal muscle, where do the nuclei lie?
Nuclei lie close to the cell surface
Muscle plasma membrane = ‘_’
Sarcolemma
The occasional folds of the sarcolemma into the interior of the cell are called…
T-tubules (Transverse-tubules)
Muscle cytoplasm = ‘_’
Sarcoplasm
Muscle endoplasmic reticulum = ‘_’
Sarcoplasmic reticulum
What is the function of the T(transverse)-tubules
To ensure the myofibrils deep into the muscle depolarise, not just the cells on the outside
The thick filaments =
Thick = Myosin
The thin filaments =
Actin
The dark bands are called the…
A-bands
The light bands are called the…
I-bands
Describe the A-band
A-band = Myosin & some overlapping actin
Describe the I-band
I-band = Thin actin filaments only
A myofibril is made up of many short units called ____
A myofibril is made up of many short units called sarcomeres
The Z-lines mark…
The ends of each sarcomere
The M-line marks…
The middle of the myosin fibres (and the middle of each sarcomere)
The H-zone =
Only myosin filaments
State the three differences of a contracted sarcomere, compared to a relaxed one
Contracted =
a) A-bands stay the same length
b) I-band gets shorter
c) H-zones get shorter
State the four details about myosin
Myosin =
a) Thick myofilament
b) Fibrous
c) Each myosin molecule has a tail to the M-line and a head with two protruding swellings which form the actin-myosin cross bridge
d) The heads contain ATPase
State the five details about actin
Actin =
a) Thin myofilament
b) Fibrous
c) Globular protein linked together into two chains which twist together to form the filament
d) Tropomyosin twists around the double chain and troponin complexes are attached too
e) Troponin and tropomyosin are ‘accessory pigments’
Troponin and tropomyosin are called…
Accessory pigments
State the 2 points of the sliding filament theory when the muscle is at rest
1) In a resting muscle, the actin-myosin binding site is blocked by tropomyosin
2) The myofilaments can’t slide past each other as the myosin heads can’t bind
State the 8 points of the sliding filament theory when the muscle is stimulated
1) AP from motor neurone stimulates muscle cell and depolarises the sarcolemma. Depolarisation spreads down the T-tubules to the sarcoplasmic reticulum
2) Sarcoplasmic reticulum releases Ca2+ ions into the sarcoplasm
3) Ca2+ ions bind to troponin, causing it to undergo a conformational shape change which pulls the attached tropomyosin out of the actin-myosin binding site on the actin filament
4) This exposes the binding site, allowing the myosin head to bind; creating an actin-myosin cross bridge
5) Ca2+ ions activate ATP hydrolase to provide the energy for muscle contraction
6) This energy released from ATP causes the myosin head to bend; pulling the actin filament along in a rowing action
7) Another ATP molecule provides the energy for the hydrolysis of the actin-myosin cross bridge so the myosin head now detaches
8) The cycle continues so long as Ca2+ ions are present
State the 4 points of the sliding filament theory when excitation stops again
1) Ca2+ ions leave their binding sites and are moved by active transport back into the sarcoplasmic reticulum
2) Tropomyosin molecules move back; blocking the actin-myosin binding sites again
3) Muscles aren’t contracted because no myosin heads are attached to actin filaments
4) The actin filaments slide back to their relaxed position, which lengthens the sarcomere.
State the three main ways of ATP production
1) Aerobic respiration
2) Anaerobic respiration
3) ATP-Phosphocreatine (PCr) system
Describe the two points of generating ATP from aerobic respiration
a) Most ATP is generated via oxidative phosphorylation in the cell’s mitochondria (specifically the inner mitochondrial membrane – cristae)
b) Due to aerobic respiration’s requirement for oxygen, its only good for long periods of low-intensity exercise
Describe the four points of generating ATP from anaerobic respiration
a) ATP produced rapidly via glycolysis
b) The pyruvate produced by glycolysis can be converted to lactate via the lactate fermentation pathway
c) Lactate causes muscle fatigue
d) Therefore anaerobic respiration is only good for short periods of hard exercise
Describe the four points of generating ATP from the ATP-Phosphocreatine (PCr) system
a) ATP is produced by phosphorylating ADP. The phosphate group is taken from PCr
b) PCr is stored inside cells and the ATP-PCr system generates ATP very quickly
c) PCr runs out after a few seconds so this system is used for short bursts of vigorous exercise
d) The ATP-PCr system is anaerobic and alactic (doesn’t form any lactate)
State the equation for the ATP-PCr system
ADP + PCr -> (reversible reaction arrow) -> ATP + Cr (Creatine)
State the two types of muscle fibre in skeletal muscle
Fast twitch and slow twitch
Slow or fast twitch muscles?
Contracts slowly
Slow twitch
Slow or fast twitch muscles?
Used for posture e.g. back muscles
Slow twitch
Slow or fast twitch muscles?
Works for long periods of time
Slow twitch
Slow or fast twitch muscles?
Energy released slowly through aerobic respiration. Lots of mitochondria & blood vessels supply the muscles with oxygen
Slow twitch
Slow or fast twitch muscles?
Red in colour due to myoglobin (oxygen)
Slow twitch
Slow or fast twitch muscles?
Smaller store of Ca2+ ions in the sarcoplasmic reticulum
Slow twitch
Slow or fast twitch muscles?
Small amounts of glycogen
Slow twitch
Slow or fast twitch muscles?
Slower rate of ATP hydrolysis in myosin heads
Slow twitch
Slow or fast twitch muscles?
Good for endurance activities
Slow twitch
Slow or fast twitch muscles?
Contracts quickly
Fast twitch
Slow or fast twitch muscles?
Used for fast movement e.g. eyes
Fast twitch
Slow or fast twitch muscles?
Fatigues quickly
Fast twitch
Slow or fast twitch muscles?
Energy released quickly through anaerobic respiration and the ATP-PCr system. Few mitochondria or blood vessels
Fast twitch
Slow or fast twitch muscles?
White in colour, not much myoglobin or oxygen
Fast twitch
Slow or fast twitch muscles?
Larger store of calcium ions in sarcoplasmic reticulum
Fast twitch
Slow or fast twitch muscles?
Larger amounts of glycogen and phosohocreatine
Fast twitch
Slow or fast twitch muscles?
Faster rate of ATP hydrolysis in myosin heads
Fast twitch
Slow or fast twitch muscles?
Good for short bursts of speed and power
Fast twitch
