| What joins bones together? | ligaments |
| What attaches muscles to bones? | tendons |
| What are skeletons? (3) | rigid frameworks that provide support and protection for organs
can be internal (endoskeletons or external (exoskeletons) = act as levers
surface for muscle attachment (Anchorage) allow movement |
| difference between endoskeleton and exoskeleton | Endoskeletons are made up of several bones that anchor muscles and act as levers while exoskeleton are made of connected segments |
| What are synovial joints? (3) | capsules that surround the joining surfaces of two bones to maintains structural stability
by allowing certain movements but not others |
| what are the 3 main components of a synovial joint? | Joint capsule = seals joint space for stability = restricts movements
Cartilage = lines bone surface for smoother movement + absorbs shock and distributes load
Synovial fluid = oxygen and nutrition to cartilage + lubrication by reducing friction |
| What are the 6 main types of synovial joints (least mobile = most mobile) | plane joints
hinge joints
pivot joints
condyloid joints
saddle joints
ball and socket joints |
| What is a hinge joint? example? (3) | angular movement in one directions (flexion and extension)
small amount of rotation
eg: human elbow joint which is between the humerus and radius /ulna |
| Draw a human elbow joint with labels (8) | humerus = anchorage (static)
Radius (forearm lever for biceps)
Ulna (forearm lever for triceps)
Biceps = bends forearm (flexion)
Triceps = straightens forearm (extension)
Joint capsule = seals joint space (stability)
Synovial fluid = lubrication
Cartilage = smooth movement (reduces friction) and absorbs shock |
| How do muscles work for movement? (4) | muscles contract to provide the force needed for movement
connected to bonds with tendons
connects a static bone (origin) to a moving bone (insertion)
skeletal muscle works in antagonistic pairs (one contracts while other relaxes) |
| Examples of opposing movements with muscles (3) | flexion vs extension
abduction vs adduction
protraction vs retraction |
| What are the three main types of muscular tissue in humans? | skeletal muscle = voluntary movements
smooth muscle = lining of internal organs
cardiac muscle = contractions of the heart |
| Example of antagonistic muscle pair in animals? (4) | in the jointed exoskeleton of a grasshopper's hind leg
= specialized for jumping
hind leg is separated into 3 parts:
femur (upper)
tibia (middle)
tarsus (lower)
femur and tibia are connected with 2 antagonistic muscles = flexor and extensor tibiae muscles |
| Explain how an insects hind legs are used to jump? (3) | when flexor muscle causes the hind leg to bend and prepare for the insect to push off the ground
when Extensor muscle contracts to cause the hind leg to straighten = launch
When one contracts the other relaxes |
| Describe the organization of skeletal muscles (4) | FASCICLES: made of tightly muscular bundles (fascicles) surrounded by connective tissue (perimysium)
MUSCLE FIBRES: Each bundle contains multiple muscle fibres formed from fused muscle cells (multinucleated)
MYOFIBRILS: muscle fibres are made up of myofibrils which are responsible for contraction
SARCOMERES: myofibrils divide into repeating sections called sarcomeres |
| What are the specialized features of a muscle fibre? (5) | multinucleated = fibres form from the fusion of individual muscle cells
Many mitochondria = muscle contraction needs a lot of ATP usage
Sarcoplasmic reticulum = internal membrane network is specialized to store calcium ions (Ca 2+)
Sarcolemma = continuous membrane which has invagination (inside out pouches) for depolarisation (T tubules)
Myofibrils = causes contraction, are made of actin and myosin myofilaments (striated) |
| What are sarcomeres? (5) | repeating contractile units which are made of myofilaments, actin and myosin
myosin is thick and binds to regions on actin (thin)
movement of the 2 filaments, causes the lengthening and shortening of the sarcomere
Myosin has small heads which bind to regions on actin
A sarcomere has a protein disc called Z line on both sides which holds the myofilaments in place |
| Describe the pattern of a sarcomere (4) | striated pattern bec of thin and thick
centre is darker bec of overlap from actin and myosin (A band)
outsides are lighter bec of only actin present
In the A band there is a slightly lighter H zone with only myosin |
| Draw a labelled sarcomere + pattern | myosin is thicker than actin filaments
myosin should show the protruding heads
(form cross bridge with actin)
A band = dArk I band = LIght |
| What are the 4 stages of muscle contraction? | 1: Sarcolemma depolarization and calcium ion release
(nerves stimulate muscle fibre)
2: Actin and myosin cross-bridge formation
(Exposes binding sites on A and M)
3: Sliding mechanism of actin and myosin filaments
(actin filaments moves across the myosin)
4: Sarcomere shortening
(muscle fibres contract = movement) |
| What does muscle contraction need, to occur? | energy intensive so it needs high levels of ATP |
| What happens in the 1st stage of muscle contraction? (4) | Sarcolemma depolarisation:
motor neuron releases a neurotransmitter (Acetylcholine) into motor end plate
triggers depolarisation of the sarcolemma (spreads through muscle fibres by T tubules)
causes Ca ions to be released from the sarcoplasmic reticulum
= starts muscle contraction in sarcomere |
| What is the 2nd stage of muscle contraction? (4) | Cross Bridge formation
Ca ions bind to regulatory protein troponin which displaces tropomyosin which exposes the binding sites
the actin binding sites form cross bridges with the myosin heads |
| What is the 3rd stage of muscle contraction? (6) | Sliding mechanism w/ myofilaments
ATP binds to myosin head = breaks cross bridge
ATP hydrolysis causes the head to turn and detach from ADP
Myosin head binds to the next binding site and turns back which pulls the actin forward
= shortening of sarcomere (muscle contraction)
== contraction needs a lot of ATP |
| What is the 4th stage of muscle contraction? (3) | sarcomere shortening and muscle contracts
Z lines are pulled closer together bec actin filaments are attached to them
I band becomes narrower, A band same, H zone reduced
muscle fibres as a whole contracts |
| Summarise muscle contraction (7) | motor neuron = releases Ca ions from SP reticulum
Ca binds to trop causes tropomyo to move = exposes binding sites for myosin heads
actin + myosin form crossbridge that is broken by ATP
ATP hydrolysis causes myosin to swivel and change position
moved heads binds to actin
Returns to original position (Releases ADP + P)
Moves the actin to the center of the sarcomere
actin sliding = shortens sarcomere = muscle contraction |
