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51 Cards in this Set
- Front
- Back
- 3rd side (hint)
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What is skeletal muscle and what does it do? |
Covers the skeleton and allows bones to be moved relative to one another Essential for voluntary movement but is also constantly used to maintain posture |
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What is a ligament? Function and properties? |
Ligaments are short bands of tough and flexible fibrous connective tissue. Elastic to allow for movement They connect bones together |
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What is a tendon? Function and properties |
Flexible but inelastic cord of strong collagen fibres Connects muscles to bones |
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What is a synovial joint? |
A point where two bones meet. The joint contains synovial fluid to act as a cushion between bones (along with cartilage) and also to nourish cartilage Completely enclosed joint capsule is formed from ligamentous connective tissue Most common joint in the body |
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What are the three types of muscle? |
Cardiac, smooth and skeletal |
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What are the four main properties of muscle tissue? Define each |
Excitability - ability to respond to stimuli Contractibility - ability to contract Extensibility - ability to extend without tearing Elasticity - ability to return to normal shape |
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What is an antagonistic pair and why do we need them? What is it composed of? Give an example of an antagonistic pair |
Muscles that work together to move a bone. Muscles can only pull, so for a joint to be able to move more than one way there must be at least 2 muscles controlling it An extensor and flexor muscle Your bicep and tricep are an antagonistic pair |
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What does a flexor muscle do? |
As it contracts it causes the joint to bend |
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What does an extensor muscle do? |
As it contracts the joint straightens again |
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What is a neuro-muscular junction? |
The gap between a neurotransmitter and an effector (muscle) |
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What are the functions of the skeleton? How many bones are in the skeletal system |
Protection Support Movement To make blood cells in marrow To store minerals About 206 |
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Describe the structure of a synovial joint (from inside to outside) |
Synovial fluid and cartilage (on the bone ends) are enclosed in the synovial membrane. Ligaments then join the bones together in the next layer. Outer layer is muscle, which is connected to bones by tendons |
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What are the 4 types of synovial joints? Give examples of each |
Plane joints - intercarpal joints Hinge joints - elbow, ankle Pivot joints - radio-ulnar joint Ball and socket - hip, shoulder |
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What types of muscle fibre is skeletal muscle composed of? |
Fast twitch and slow twitch |
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What system controls the skeletal muscle and how? |
The voluntary nervous system. Sends messages from the central nervous system to the muscle tissue |
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Features of skeletal muscle? |
Very large cells (muscle fibres) Multinucleated Nuclei around periphery Striated appearance Long straight cells Involved in voluntary movement |
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Features of cardiac muscle? |
Small cells Mononucleated Striated Cells are joined by protein channels called intercalated discs |
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Features of smooth muscle |
Cells are spindle shaped, short and thin Each cell has a single nucleus Unstriated |
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Describe general muscle structure |
A single muscle contains approximately 1000 fibres, all joined together at the tendons |
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Describe the structure of a muscle cell |
100 micrometres in diameter and a few cm long Many nuclei Cytoplasm is packed with myofibrils - bundles of protein filaments that cause contraction Sarcoplasm (muscle cytoplasm) also contains mitochondria to provide energy for contraction |
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What is fast twitch muscle fibre used for? General facts |
-Used for short bursts of activity as contractions are powerful and quick -Respire anaerobically and store a large amount of phosphocreatine in their cytoplasm. Provides a quick source of ATP during sudden exercise -lactate produced as a byproduct of anaerobic respiration causes fast twitch fibres to become tired fast |
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What is slow twitch muscle fibre used for? General facts |
-Used during endurance activities as they contract slowly and can work for long periods of time -Large number of mitochondria - High concentration of myoglobin (carries O2 into muscle cells) -Excellent blood supply -These adaptations help to maintain aerobic respiration so slow twitch fibres are slow to fatigue -ATP generation is slower than in fast twitch -contractions are weaker |
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Describe the structure of a myofibril |
Contains 2 types of filaments. Thin ones are made of actin, thick ones of myosin Filaments are arranged into an interlocking pattern producing the banded pattern of myofibrils |
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What creates the dark band in myofibrils? What creates the light band? |
The dark band is the region containing actin and myosin The light band is the region containing just actin (thin filaments) |
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What is a sarcomere? |
A structural unit of a myofibril in striated muscle tissue |
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The interlocking structure of thick and thin filaments allows them to slide past each other, reducing the length of the sarcomere |
As filaments become more interlocked the light bands shrink as there are fewer regions containing just actin |
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This is a relaxed sarcomere |
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What is the I band (dark band) |
The section of a sarcomere that contains just actin |
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What is the H band? |
The section of a sarcomere that contains just myosin |
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What is the A band (dark band) |
The length of the myosin. (There is some overlap with actin which creates the dark area) |
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What is a z line? |
The end of a sarcomere |
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What happens when a sarcomere contracts (in terms of bands) |
A band remains the same size as the length of myosin is unchanged I band shrinks H band shrinks as actin and myosin overlap |
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Describe the structure of myosin |
Formed from a number of myosin proteins wound together. Each ends in a myosin head, which contains Atpase. When this breaks down ATP energy is released to move the myosin heads. Heads also contain an actin binding site and an ATP binding site |
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Describe the structure of actin |
Formed from a helix of actin sub-units. Each contains a binding site for myosin heads. Two other proteins are attached to the actin fibre: Tropomyosin is wound around the actin, covering binding sites Troponin molecules are bound to tropomyosin and contain calcium binding sites |
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What is a neuromuscular junction? |
The gap between a neurotransmitter and a muscle (effector) |
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What is the sarcoplasmic reticulum? |
Specialised endoplasmic reticulum in cardiac and skeletal striated muscle. Functions as a storage and release area for calcium ions. A system of membrane bound sacs around the myofibrils |
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How does the arrival of a nerve impulse at the neuromuscular junction cause the release of calcium ions? |
The motor neurone releases acetylcholine which binds to receptors on the membrane of the muscle fibre (the sarcolemma). Neurotransmitter stimulates the release of calcium ions from the sarcoplasmic reticulum |
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How do calcium ions initiate the movement of protein filaments? |
Calcium ions bind to troponin molecules causing them to move This results in tropomyosin shifting to uncover myosin binding sites on the actin filament Myosin heads bind to the sites to form cross bridges ADP and Pi are released from the heads, causing them to change shape. The heads nod forwards resulting in the attached actin filament moving over the myosin ATP molecules bind to each head, causing them to detach from actin sites ATPase hydrolysed ATP into ADP and Pi - the shape of the heads changes again, returning them to their upright position Process can begin again |
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What causes muscle contraction? |
The bending of many myosin heads combining to move the actin filament relative to the myosin filament |
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How long does muscle contraction continue for? |
As long as ATP and calcium ions are present, and an impulse hasn't been sent to inhibit the release of calcium (which would stop the process from continuing) |
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How do you calculate cardiac output |
Stroke volume × heart rate |
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What is stroke volume |
The volume of blood pumped out of the left ventricle each time it contracts (cm^3) |
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What is heart rate |
The number of beats (contractions) per minute |
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How do you convert between cm^3 and dm^3? |
Divide by 1000 to get dm^3 Multiply by 1000 to get cm^3 |
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What are the three stages of the cardiac cycle? |
Atrial systole Ventricular systole Diastole |
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What factors affect stroke volume? |
Venous return - the volume of blood returning to the heart during the cardiac cycle Force of muscular contraction |
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What is the typical resting heart rate? |
60 to 100 bpm |
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What is meant by the term myogenic in terms of the heart? |
Impulses to contract originate from inside the heart. Doesn't need impulses from external sources (the brain) to function at resting heart rate |
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What does the heart need impulses from the brain for? |
To cause increases or decreases in the heart rate |
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Describe the sequence of events that lead to one heart beat |
Sinoatrial node (found in right atrium) generates initial impulses which spread across both atria, causing atrial systole A non-conducting layer of tissue between atria and ventricles stops the impulses from spreading to the ventricles The atrioventricular node sends impulses to the bundle of His after a short time delay (0.13 ms) Impulses then pass down the purkyne fibres to the heart apex and spread up through the ventricle walls This causes ventricular systole and blood is squeezed into the aorta |
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Why is there a time delay before the AVN sends impulses? |
Allows atria to fully contract and the ventricles to fill |
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