Membrane potential of muscles The interstitial fluid and the intracellular fluid contain 147 mEq/litre of positive ions (cations) outside the cell, and about 155 mEq /L, of negative ions (anions) inside the cell. Higher concentration of Na+ ions (142 mEq/L) and lower concentration of K+ ions (5 mEq/L) characterise the interstitial fluid. The intracellular fluid has more […]
Excitability of muscles Excitability of muscles is the ability of any living cell or tissue to exhibit an electrochemical change (action potential) to a stimulus. However, nerve and muscle cells are highly excitable cells than other cells. Events of action potential of muscle fiber The action potential is caused by a sequence of changes or
Excitation Contraction Coupling The arrival of an Action Potential at Sarcoplasmic Reticulum causes release of Ca2+ down the concentration gradient to sarcoplasmic reticulum. Released Ca2+ causes conformational changes to effect contraction. As action potential passes, Ca2+ are pumped again to sarcoplasmic reticulum and relaxation happens. This cycle is known as Excitation Contraction Coupling.
Myosin and Actin filament Myosin Filament It is composed of multiple myosin molecules, each molecule having a molecular weight of 480,000. It has two polymerized portions, Heavy meromyosin and Light meromyosin . Heavy meromyosin is formed by HMM – S1 and HMM – S2 molecules. The myosin molecule is made up of six polypeptide chains: 2 heavy chains and 4 light chains. The two heavy chains
Sarcoplasm and Myofibrils Sarcoplasm Sarcoplasm is the fluid present inside each fiber in which the organelles like sarcosomes(mitochondria), sarcoplasmic reticulum and myofibrilare suspended. Large number of sarcosomes is placed in between the myofibrils, indicates the large quantity of energy (ATP) requirement for the contraction of fibrils. Cytoplasm of the muscle cell is called sarcoplasm which contains myoglobin.
Structure of muscle A muscle has an origin (less movable), belly and the insertion (highly movable) parts. Muscles are surrounded by a sheet of connective tissue called epimysium (site for fat deposition). From epimysium smaller sheets of connective tissue called perimysium arise and divide muscle into several small bundles. This perimysium contains blood vessels, nerves and muscles spindles. Perimysium
Types of muscles In mammal three kinds of muscles tissue are found, these types of muscle are Skeletal muscles, Cardiac muscle and Smooth muscle. Skeletal muscles Cross striated and attached to skeleton, 40% of the total body weight, Voluntary neural control. Cardiac muscle Cross striated in structure, Involuntary in function, Under autonomic nervous system control.
Electron microscopic structures of muscle fibers Myofibril Muscle fibres are made up of several hundred to several thousand of parallely arranged myofibrils having the special function of contraction. Each myofibril posses the contractile proteins myosin (thick) and actin (thin) myofilaments results in regular repetition of dark and light bands in the skeletal and cardiac muscles. Each muscle fibre contains about
Electron microscopic structures of muscle fibers Read More »
Transduction of taste There are primarily five tastes like salty, sour, sweet, bitter, and umami. The salt taste is mainly due to the Na+ ions. So the salty food causes opening of the Na+ channels. The substance namely Amiloride inhibits the receptor channels and diminishes the salt sensation of the receptors. The sour taste is due to the
Gustation in animals Gustation in animals is the process of detecting dissolved chemicals emitted from the ingested food. It is the sense of taste. This is carried out by receptor known as taste buds. There are almost 15,000 taste buds in the porcine oral cavity and throat, while 1 550 in the lizards, but only 24 in chickens.
