11.2 Movement Flashcards
The ability to move is controlled by which body systems?
Skeletal, muscular and nervous system
What is the skeletal system?
Consists of bones that act as levers and provide a structure for the muscles to pull
What is the muscular system?
Muscles deliver the force required to move one bone in relation to another
What is the nervous system?
Delivers signals to the muscles which cause them to contract and create movement
What are skeletons?
A rigid framework that provide support and protection for organs
What are the two types of skeleton?
Internal and external
What is an internal skeleton called?
Endoskeleton
What is an external skeleton called?
Exoskeleton
What is the difference between endo and exoskeletons?
Endoskeletons consist of numerous bones whereas exoskeletons are comprised of connected segments
How do skeletons facilitate the movement of an organism?
They provide a surface for muscle attachment
How are bones connected to other bones?
By ligaments
What do bones and exoskeleton move in response to?
Muscular contraction
How are bones connected to muscles?
Tendons
What are synovial joints?
Capsules that surround the articulating surfaces of two bones
What do joints function to do?
Maintain structural stability by allowing certain movements but not others
What are the three components of synovial joints?
Joint capsule
Cartilage
Synovial fluid
What does the joint capsule do?
Seals the joint space and provides stability by restricting the range of possible movements
What does cartilage do?
Lines the bone surface to facilitate smoother movement and absorbs shock and distributes load
What does synovial fluid do?
Provides oxygen and nutrients to the cartilage as well as lubrication to reduce friction
What are the six main types of synovial joints?
Plane joints
Hinge joints
Pivot joints
Condyloid joints
Saddle joints
Ball and socket joints
What is an example of a hinge joint?
Elbow joint
Where is the elbow joint located?
Between the humerus and radius/ulna
What type of movement is the elbow capable of?
Angular movement in one direction
What are the bones in the elbow joint?
Humerus
Radius
Ulna
What does the humerus do?
Anchors muscle
What does the radius do?
Acts as a forearm lever for biceps
What does the ulna do?
Acts as a forearm for triceps
What are the muscles in the elbow joint?
Biceps
Triceps
What does the biceps do?
Bends the forearm (flexion)
What does the triceps do?
Straightens the forearm (extension)
What do muscles do?
Contract to provide the force required for movement
What types of bone does muscle connect?
A static bone to a moving bone
What do skeletal muscles exist in and why?
Antagonistic pairs to enable opposing movements
What are three examples of opposing movement?
Flexion vs extension
Abduction vs adduction
Protraction vs retraction
What do many insects have that are makes them jump?
Hind legs specialised for jumping
What are the three parts of the exoskeleton of the hind leg?
Femur - upper leg
Tibia - middle leg
Tarsus - lower leg
What are the two antagonistic muscles that connect the femur and tibia?
Flexor tibiae muscle and extensor tibiae muscle
What happens when the flexor muscle of the hind legs contracts?
The extensor muscle relaxes and the tibia and femur are brought closer together
What does retracting the hind quarters prepare for?
Pushing off the ground
What happens when the extensor muscle contracts?
The flexor muscle relaxes and the tibia is pushed away from the femur
What does extending the hind quarters do?
Causes the insect to jump
What does skeletal muscles consist of?
Tightly packaged muscular bundles surrounded by connective tissue
What does each muscular bundles contain?
Multiple muscle fibres
How are muscle fibres formed?
When individual muscle cells fuse together
What do muscle fibres contain?
Tubular myofibrils that run the length of the fibre
What are myofibrils responsible for?
Muscular contractions
What does each sarcomere represent?
A single contractile unit
What are the five ways muscle fibres have specialised functions to facilitate muscle contraction?
Multinucleated
Large number of mitochondria
Specialised endoplasmic reticulum
Contain tubular myofibrils made of two different myofilaments
Continuous membrane containing T Tubules
Why does muscle fibres have multiple nuclei?
Fibres form from the fusion of individual muscle cells and hence have many nuclei
Why do muscle fibres have a large number of mitochondria?
Because muscle contraction needs ATP hydrolysis
How is the endoplasmic reticulum specialised in muscle fibres?
It is called sarcoplasmic reticulum and stores calcium ions
What are the two types of myofilaments?
Thin filament - actin
Thick filament - myosin
What is the continuous membrane surrounding the muscle fibre called?
The sarcolemma
What do myofibrils consist of?
Sarcomeres
What is the thick filament called?
Myosin
What does myosin contain and what do they do?
Small protruding heads which bind to regions of actin
What does the movement of the two filaments together cause?
The lengthening and shortening of the sarcomere
What holds the myofilaments in place?
Z lines
What are the dense protein discs that flank each individual sarcomeres called?
Z lines
What radiates out the Z discs?
Actin filaments
What helps anchor the central myosin filaments in place?
The actin filaments
The recurring sarcomeres produce what type of pattern along the length of the skeletal muscle fibres?
A striped pattern
What colour is the centre of the sarcomere?
Darker
Why is the centre of the sarcomere darker?
Due to an overlap of actin and myosin filaments
What colour are the peripheries of the sarcomere?
Light
Why are the peripheries of the sarcomere lighter?
Only actin is in the region
Why will the centre of the sarcomere have a slightly lighter central region?
Only myosin is present
If colouring in the band of sarcomere? (from left to right)
Light dark medium dark light
What are the four main steps of muscle contraction?
Depolarisation and calcium release
Actin and myosin cross bridge formation
Sliding mechanism of actin and myosin filaments
Sarcomere shortening
What triggers the release of acetylcholine into the motor end plate?
An action potential from a neuron triggers the release
What does acetylcholine do?
Initiates depolarisation within the sarcolemma
How is depolarisation spread through muscle fibres?
T tubules
What does depolarisation cause?
The sarcoplasmic reticulum to release stores of calcium ions
What plays a pivotal role in initiating muscular contractions?
Calcium ions
On actin, what covers the binding sites for the myosin heads?
A blocking complex of troponin and tropomyosin
What causes the exposing of the binding sites for the myosin heads?
Calcium ions bind to troponin and reconfigure the complex
What does a cross bridge form between?
The myosin heads and the actin filaments
What does calcium ions bind to?
Troponin
What does ATP bind to?
The myosin head
What does ATP binding to the myosin head do?
Breaks the cross-bridge between actin and myosin
What does ATP hydrolysis do?
Causes the myosin heads to change position and swivel and moves them towards the next actin binding site
What does the myosin heads do to the new actin sites?
Bind to them and return to their original conformation
What does the reorientation of the myosin heads do to the actin?
Drags the actin along the length of the myosin in a sliding mechanism
What are the actin filaments anchored to?
Z lines
What pulls the Z lines closer together?
The dragging of actin
What does pulling the Z lines closer together do?
Shortens the sarcomere
What happens as the individual sarcomeres become shorter in length?
The muscle fibres as a whole contracts
What happens when the calcium ions binf to troponin?
Tropomyosin moves
What breaks the cross bridge?
ATP
What is released when myosin heads return to their original configuration?
ADP + Pi
