Movement Flashcards
(23 cards)
What’s is the purpose of locomotion?
Foraging for food, escaping from danger, searching for a mate and migration
Purpose of movement - muscles and mobility
- bones and exoskeletons acting as levers
- antagonistic pairing of muscles
Function of joints
Structure and function of muscle fibres
Contraction of skeletal muscle
What is a skeleton?
Is a rigid framework that function to provide support and protection for body organs.
- skeletons can be internal (endoskeletons) or external (exoskeletons) depending on the organism.
- endoskeletons typically consist of numerous bones, while exoskeletons are comprised of connected segments
Skeletal system
Consists of bones that act as levers and provide a structure for the muscles to pull.
Muscular system
Muscles deliver the force required to move one bone in relation to another.
Nervous system
Delivers signals to the muscles which cause them to contract and create movement.
Examples of interacting systems
Anchor - cheek bone
Lever - jaw bone
Muscle - masseter muscle
Why do skeletons work as levers?
Bone = lever
Joint = fulcrum
Muscle contraction provides effort force on the bone.
Weight of body part being moved is the load.
First class lever
Have fulcrum placed between load and effort.
Second class lever
Have load between effort and fulcrum
Third class lever
Have effect between the load and fulcrum
Types of joints
Ball and socket joints
E.g. Shoulder and hip
Can move bones along several axes:
- out and in (abduction and adduction)
- forward and backward (flexion and extension)
- full circle (rotation)
- protraction and retraction
Hinge joints
E.g. ankle, elbow and knee
Bones only move along one axis:
- forward and backwards (flexion and extension)
Skeletal muscle
- work in antagonistic pairs (opposite movements)
- when one contracts the other relaxes producing opposite movements in a joint
E.g. biceps and triceps
How does a muscle work?
Muscles work by getting shorter. We say that they contract.
Muscles are attached to bones by strong tendons. When a muscle contracts, it pulls on the bone and the bone can move.
What are the three types of muscles vertebrates have?
Skeletal muscle: contraction creates movement body parts. These are the only muscles that can be under voluntary control.
Cardiac muscle: make up the heart. Their contraction creates the force that propels blood through the body.
Smooth muscle cells: line the walls of many internal organs and are responsible for pushing food through the digestive system and regulating blood pressure.
Myofibril sarcomere
Myofibrils composed of repeating structures called sarcomeres, appear under microscope as dark and light bands. Sarcomeres are composed of long, fibrous proteins that slide past each other when a muscle contracts or relaxes.
What is a sarcomere?
What gives muscles their striated appearance.
Is defined as the segment between two neighbouring z-lines. Z lines are made of several proteins.
Interaction between actin and myosin of the sarcomere is responsible for the muscle contraction.
What is actin?
A round protein shaped like a ball. In the sarcomere, many of these actin molecules are linked together in a long chain to form a strand called the thin filament.
What is myosin?
A long thin protein with a head on it. Many of these myosin proteins are linked together in a bundle, also forming a filament with the heads positioned away from each other.
What is Titin?
Elastic and acts like a spring
Stores potential energy when it is stretched and releases this energy when it recoils.
Purpose?
Holds myosin filament, prevents overstretching and adds force of a contraction by releasing energy
How does a skeletal muscle contraction work?
- An action potential from a motor neuron triggers the release of vesicles into the motor and plate.
- The vesicles release neurotransmitter into the synaptic cleft and attach to receptors.
- It initiates action potential within the sarcolemma, which is spread through the muscle fibre via T tubules.
- Depolarisation causes the sarcoplasmic reticulum to release stores of calcium ions (Ca2+)
- On actin, the binding sites for the myosin heads are covered by a blocking complex.
- The myosin heads then form a complex with the actin filaments.
- Calcium returns to the sarcoplasmic reticulum by active transport.
How does a sliding filament mechanism work?
- Myosin head binds ATP and detaches from actin.
- ATP hydrolysis causes myosin head to swivel.
- Swivelled myosin head detaches ADP and binds to actin in new position.
- Myosin head returns to original configuration, moving the actin strand.
Adaptation of marine mammals
Streamline: smooth body surface, skin without hair, elongated teardrop profile, widest at front.
Adaptations for locomotion: flipper for steering, flukes, dorsal fins, blubber.
Ventilation: blowhole leading from the larynx to the upper surface of the head.
No connection between the mouth and lungs to avoid water entering the lungs.
