7.1 Getting moving Flashcards
converting between speeds
e.g mph to m/s 59 mph to m/s
1609.3 m in a mile
so do s=59/1 x 1609.3
= 94948.7/60*
Flex
When the angle between two bones decreases the joint is said to flex. For example, when you bend your arm you are flexing the elbow joint.
Extend
When the angle between two bones increases the joint is said to extend. For example, when you straighten your arm you are extending the elbow joint.
Joint
Joints occur where two or more bones meet. In fixed joints the bones are joined together with fibrous tissue and there is no movement. In cartilaginous joints the bones are joined together by cartilage and there is limited movement. In synovial joints there is free movement of the bones. A fluid filled cavity enclosed within a fibrous capsule separates the bones.
Antagonistic
Muscles are described as antagonistic because they work in pairs. Each member of the pair can only pull. A pair of antagonistic muscles flex and extend the knee. The hamstring muscles at the back of the thigh contract and bend the knee; the quadriceps contract when the leg is straightened. The hamstring muscle and the quadriceps are antagonistic.
Extensor
The muscle that on contraction causes a joint to extend. For example, the extensor when you straighten your arm is the triceps
Flexor
The muscle that on contraction causes a joint to flex is the flexor. For example, to bend your arm you contract the biceps; this is the flexor.
Synovial joint
A moveable joint such as the hip joint or knee joint. The bones which articulate in the joint are separated by a cavity filled with synovial fluid which enables them to move freely.
Synovial fluid
The fluid inside a synovial joint such as a hip or knee joint. It is secreted by the synovial membrane and acts as a lubricant
Ligament
A strong flexible strip of connective tissue that attaches bones to each other. Ligaments restrict the movement of joints.
Tendon
A strip of connective tissue that attaches a muscle to a bone. A tendon is flexible but very resistant to stretching. These properties allow contraction of the muscle to bring about the movement of bones. Inelastic to allow the transfer of force from muscle contraction to bone.
Cartilage
A strong, flexible supporting tissue important in skeletons. Cartilage is compressible, so it is often found at the ends of bones in joints where it can act as a shock absorber and withstand the jarring that would otherwise occur when an animal moves. Its flexibility makes it useful in supporting structures such as the ears, nose and trachea.
Synovial membrane
secrete synovial fluid
Fibrous capsule
encloses joint
Muscle fibres
Bundles of muscle fibres make up a muscle. A muscle fibre is a single cell, surrounded by a cell surface membrane, also known as a sarcolemma. It contains several nuclei as well as mitochondria and other organelles. Within each muscle fibre there are many smaller myofibrils.
Multinucleate
A cell, or other structure bounded by a plasma membrane, which contains more than one nucleus. Muscle fibres and the hyphae of many fungi are multinucleate.
Myofibril
One of the thin fibrous structures within a muscle fibre. Each myofibril consists of repeated contractile units made of thin fibres of the protein, actin, and thick fibres of another protein, myosin. Each of these contractile units is called a sarcomere.
Sarcomere
One of the repeated contractile units which makes up a myofibril within a muscle fibre. Each sarcomere consists of thin fibres of the protein actin, thick fibres of another protein, myosin, and two associated proteins, troponin and tropomyosin. When the muscle contracts, the actin moves between the myosin, shortening the length of the sarcomere. This causes the muscle to contract
Actin
A protein found in many cells. Actin plays an important part in muscle contraction. In a muscle fibre, actin forms the thin filaments. These filaments slide between the thicker filaments of another protein, myosin, bringing about muscle contraction. It is also thought to be involved in cell cleavage.
Myosin
A protein which is important in muscle contraction. The thick myosin filaments slide between the thinner filaments of another protein, actin, bringing about muscle contraction. It is thought that this protein is also involved bringing about the division of the cytoplasm when new cells are formed during cell division
Troponin
A molecule associated with actin on the thin filaments of a muscle myofibril. When a muscle is stimulated to contract, calcium ions attach to the troponin molecules and cause them to move. As a result, tropomyosin on the actin filaments changes its position, exposing myosin binding sites on the actin
Tropomyosin
A protein associated with actin on the thin filaments of a muscle myofibril. When a muscle is stimulated to contract, calcium ions attach to troponin molecules and cause them to move. As a result, the tropomyosin changes its position, exposing myosin binding sites on the actin
Sliding filament theory
The theory that muscle contraction is the result of the relative movement of actin and myosin filaments due to their interactions within the muscle myofibril.
Neuromuscular junction
A synapse between a nerve cell and a muscle.
Sarcoplasmic reticulum
A specialised type of endoplasmic reticulum found in muscle fibres. The sarcoplasmic reticulum forms a series of membrane-bound sacs around the myofibrils. Calcium ions released from these sacs into the sarcoplasm bring about the process of muscle contraction
Sarcoplasm
The cytoplasm within a muscle fibre. Each muscle fibre is a single cell. It contains cytoplasm just as do other cells. Within the sarcoplasm are several nuclei, as well as mitochondria and other organelles
Sarcolemma
The cell surface membrane
surrounding a muscle fibre. Each muscle fibre is
a single cell. It is surrounded by a membrane just
as are other cells.
