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Functionally cardiac muscles are similar to :-
Cardiac muscle is highly organized and bears striking similarities to skeletal muscle in terms of its basic morphology.
Functionally cardiac muscles resemble unstriped muscles, as both of them are involuntary muscles and have the function of contraction and relaxation.
Covering of muscle :-
Fascia (or "deep fascia") is a layer of thickened connective tissue that covers the entire muscle and is located over the layer of epimysium.
Myofibrils contain :-
Myofibrils are composed of long proteins including actin, myosin, and titin, and other proteins that hold them together. These proteins are organized into thick and thin filaments called myofilaments, which repeat along the length of the myofibril in sections called sarcomeres. Muscles contract by sliding the thick (myosin) and thin (actin) filaments along each other.
The globular head is an acitve ATPase enzyme and has binding sites for ATP and active actin sites.
Cross bridge are formed during :-
In the context of muscular contraction, a cross-bridge refers to the attachment of myosin with actin within the muscle cell.All muscle types contract by cross-bridge cycling i.e. repeated attachment of actin and myosin within the cell.
Hence, a cross-bridge is formed during muscle contraction.
Time between two successive contraction :-
A refractory period is a period of time during which an organ or cell is incapable of repeating a particular action, or (more precisely) the amount of time it takes for an excitable membrane to be ready for a second stimulus once it returns to its resting state following an excitation.
During contraction of muscles :-
Sliding Filament Theory of Contraction:During muscle contraction, the thin actin filaments slide over the thick myosin filament.When Calcium is present the blocked active site of the actin clears.
Purkinje fibers:-
Purkinje fibers: The specialized cardiac muscle fibers forming a network in the ventricular walls that conduct electric impulses are responsible for the contractions of the ventricles.
Mitochondria in cardiac muscles :-
Cardiac muscle cells have a high mitochondrial density in comparison to other muscles fiber, which allows them to produce adenosine triphosphate (ATP) quickly, making them highly resistant to fatigue.
SA Node is :-
The SA node, also known as the sinus node, which is a group of specialized muscle fibres is the heart's natural pacemaker. It consists of a cluster of cells that are situated in the upper part of the wall of the right atrium.
Rigor mortis is :-
Rigor mortis is stiffening of the joints and muscles of a body a few hours after death, usually lasting from one to four days.Rigor mortis usually sets in within four hours, first in the face and generally smaller muscles.
Red muscle fibres are more in :-
Red muscles are skeletal muscles that are rich in capillaries, myoglobin, and mitochondria. Capillaries are very small blood vessels that deliver oxygenated blood to the muscles. This oxygen is taken up by a protein called myoglobin. The myoglobin then helps provide the oxygen to the mitochondria, the sort of power plant of the cell. They use oxygen, among other things, to produce a lot of energy.
Unstriped muscle are also known as :-
Unstriped muscles have no striation, so they are called smooth muscles.
They are present in the internal body organs, so they are called visceral muscles.
They are not voluntary control like skeletal muscles, so they are called Involuntary muscles.
Myofibres also known as :-
Sarcostyles are myofibres and are one of many contractile filaments that make up a striated muscle fiber.
Contractile unit of muscle fibres :-
A sarcomere is the basic contractile unit of muscle fiber.
Each sarcomere is composed of two main protein filaments, actin and myosin, which are the active structures responsible for muscular contraction.
One of following has contractile properties :-
Actin protein is an important contributor to the contractile property of muscle and other cells.
Epimysium of muscle are made up of :-
Epimysium of Muscles are made up of white fibrous connective tissue while Perimysium and endomysium are made up of areolar tissue.
Myosin filament appear dark under microscope due to :-
Isotonic contraction takes places during :-
An isotonic contraction occurs when tension in the muscle remains constant despite a change in muscle length. Lifting an object off a desk, walking, and running involve isotonic contractions.
Largest muscle is :-
The Gluteus Maximus is the largest muscle in the human body. It is large and powerful because it has the job of keeping the trunk of the body in an erect posture. It is the chief antigravity muscle that aids in walking up stairs.
Cori cycle relationship between the :-
In the Cori cycle, lactate accumulated in the muscle cells is taken up by the liver. The liver performs a chemical process known as gluconeogenesis, to convert lactate back to glucose. This first converts lactate to pyruvate, and then finally into glucose.
Papillary muscle found in :-
The papillary muscles are muscles located in the ventricles of the heart. The papillary muscles constitute about 10% of the total heart mass.
Flight muscles of bird :-
Birds power flight primarily by large pectoralis muscles that depress the wings at the shoulder.
Contraction of shortest duration is of :-
The external muscles of the eye are conspicuously large and strong in relation to the small size and weight of the eyeball. It is frequently said that they are the strongest and fastest contracting muscles due to the constant blinking action they have to do.
Eye movements do require high-speed movements, and eye muscles are exercised continuously even during rapid eye movement of sleep.
ATP-ase activity found in :-
In all myosins, the head domain is a specialized ATP-ase that is able to couple the hydrolysis of ATP with motion. A critical feature of the myosin ATP-ase activity is that it is actin-activated. In the absence of actin, solutions of myosin slowly convert ATP into ADP and phosphate.
Total No. of muscles in our body is :-
There are total 639 muscles in human body.
Smallest muscle is ‘stapedis' found in middle ear attached with stapes (smallest bone).
Largest muscle is ‘glutious maximus' also it is the most powerful muscle of human body.
Longest smooth muscles are :-
During pregnancy, the smooth muscle of uterus expands and attains maximum size and thus becomes largest smooth muscle.
Strongest muscles :-
The strongest muscle in human beings is the masseter muscle. The muscle masseter is a thick muscle in the cheek and is situated at the back of the jaw. During chewing it is responsible for opening and closing the jaw.
Muscles of Iris & Ciliary body originate :-
The neural tube ectoderm gives rise to the retina, the iris and ciliary body epithelia, the optic nerve, the smooth muscles of the iris, and some of the vitreous humor.
Multi unit muscles Fibres found in :-
Multi-unit smooth cells can be found in the trachea, the large elastic arteries, the iris of the eye, in the lungs, erectile tissues of hair follicles ( Arrector pili of the dermis), and the vas deferens in the male genital tract.
Multi-unit smooth muscle activity can be initiated by hormones, but it is not much affected by rapidly stretching the muscle.
Cardiac muscles Fibres :-
Cardiac muscle is found only in the walls of the heart. When cardiac muscle contracts, the heartbeats and pumps blood.
Hence, option D is correct.
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