Muscular System

Unit-IIIMuscular System

Muscular SystemThemuscular systemis the anatomical system of a species that allows it to move.The muscular system makes up nearly half the weight of the human body, this is why when we train we sometimes put on weight instead of losing it. We put on muscle weight.Muscular System FunctionsBody movement (Locomotion)Maintenance of postureRespirationCommunication (Verbal and Facial)Constriction of organs and vesselsHeart beat Production of body heat

MusclesMuscles are all made of the same material, a type of elastic tissue (sort of like the material in a rubber band). Thousands, or even tens of thousands, of small fibers make up each muscle.Types of MuscleSkeletal MuscleSmooth MuscleCardiac Muscle

Skeletal musclesAttached to bonesMakes up 40% of body weightResponsible for locomotion, facial expressions, posture, respiratory movements, other types of body movementVoluntary in action; controlled by somatic motor neuronsSkeletal muscle

Structure of Skeletal muscle

Structure of Skeletal muscleSkeletal muscle attached to bones via strong bands of connective tissue calledtendons.Skeletal muscle is organised into bundles of muscle cells or fibres. that are held together by a sheath of connective tissue.

Structure of Skeletal muscleEach muscle fibre is a single cell with many nuclei. Around each cell is plasma membrane called the sarcolemmawhich containssarcoplasm(cytoplasm). Each cell/fibre is comprised of many smallermyofibrilsarranged lengthwise.

Smooth Muscle

Smooth MusclesIn the walls of hollow organs, blood vessels, eye, glands, uterus, skin.Some functions: propel urine, mix food in digestive tract, dilating/constricting pupils, regulating blood flow, in some locations, autorhythmic.Controlled involuntarily by endocrine and autonomic nervous systems.

Structure of Smooth MusclesSmooth muscle fibers have afusiformshape and, likestriated muscle, cantense and relax. However, smooth muscle containing tissue tend to demonstrate greater elasticity and function within a larger length-tension curve than striated muscle. Smooth MusclesThis ability to stretch and still maintain contractility is important in organs like the intestines and urinary bladder. In the relaxed state, each cell is spindle-shaped, 20-500 micrometers in length.

Cardiac Muscles

Heart: major source of movement of bloodAutorhythmicControlled involuntarily by endocrine and autonomic nervous systems

Structure of Cardiac Muscles

Cardiac muscle is dense and packed tightly. The muscle fibers are striated and branched and have intercalated discs. Muscle FiberA cylindrical, multinucleate cell composed of numerous myofibrils that contracts when stimulated.17Types of Muscle Fiber Types of Muscle Fiber Fast/White Twitch Muscle FiberFast twitch fibers, as the name suggests, contract more quickly thanslow twitch muscle fibersand, as a result, they produce more power and strength.

Slow/Red Twitch Muscle FiberSlow twitch fibers, as the name suggests, contract more slowly thanfast twitch muscle fibers and they can contract for a longer period of time.

Muscle Fiber

20Characteristics Of Muscle TissueExcitability: capacity of muscle to respond to a stimulus.Contractility: ability of a muscle to shorten and generate pulling force.Extensibility: muscle can be stretched back to its original length.Elasticity: ability of muscle to recoil to original resting length after stretched.