5.1.5 Voluntary And Involuntary Muscles Flashcards
What are the three types of muscle in the body
Skeletal muscle - make up the bulk of body muscle tissue. These are the cells responsible for movement I.e. biceps and triceps
Cardiac muscle - found only in heart. This muscle is myogenic so they can contract without nervous stimulation. This allows to heart to beat in regular rhythm.
Involuntary muscles - I.e. smooth muscles. These involuntary muscle cells are found in many parts of the body I.e. walls of hollow organs like the stomach and bladder. They are also found in the walls of the blood vessels and the digestive tract, where through peristalsis they move food along the gut
What is the structure and feature of skeletal muscle
Skeletal muscle is striated and is under conscious control. It’s regularly arranged so the muscle contracts in one direction. Contraction speed is rapid and length of contraction is short
What is the structure and features of cardiac muscle
They are specialised striated and are involuntary. Cells branch and interconnect resulting in simultaneous contraction. The speed of contraction is intermediate with length of contraction also being intermediate.
What is the structure and features of involuntary muscle
They are non striated and contracts involuntary. There is no regular arrangement as difference cells can contract in different directions. Contraction speed is slow and can remain contracted for a relatively long time
What is the structure of skeletal muscle fibres in depth
Skeletal muscles are made up if bundles of muscle fibres. These are in closed within a plasma membrane known as the sarcolemma. These muscle fibres has a high number of nuclei and are much longer than normal cells as they are a result of many embryonic muscle cells fusing together. This makes the muscle stronger. Muscle fibre cytoplasm is sacroplasm.
Parts of sacrolemma fold inwards to help spread electrical impulses throughout the sacroplasm. This ensures that the whole of the fibre receives the impulse to contreavt at the same time. Muscle fibres also have hella mitochondria to provide ATP for contraction. Brudda also has sacroplasmic reticulum which has the calcium ions needed to contract
What does each muscle fibres contain
Contains hella myofibrils, which are long cylindrical organelles made of protein and specialised for contractions. Very powerful in numbers and lined in parallel for maximum force when they contract. They are made of two protein filaments:
Actin - the thinner filament: two strands twisted around each other
Myosin - the thicker filament: long rod shaped fibres with bulbous heads that project to one side
What is the function of the alternative light and a dark band arrangement?
Light bands - these areas appear light as they are the regions where the actin and myosin filaments do not overlap.
Dark bands - these appear dark because the presence of thick myosin filaments. These edges are particularly fair as the myosin is overlapped with the actin.
Z line - found at the centre of each light band. The distance between the adjacent Z lines is called a sacromere. These sacromere is the functional unit of the myofibri. When muscle contracts, the sacromere shortens.
H Zone - this is a lighter coloured region round in the centre of each dark band. Only myosin filaments are present at this point. When the muscles contract the H zone decreases
What is the histology of skeletal muscle
Individual muscle fibres - long and thin multinucleated fibres that are crossed with a regular pattern of fine red and white lines
The highly structured arrangement of sacromeres which appear as dark a band and light I bands
Streaks of connective and adipose tissue
Capillaries running in between fibres
