Muscular System Flashcards
Three types of muscle tissue
skeletal, cardiac, and smooth
Over 600 muscles in the human body or muscles have these three properties in common
-Excitability: all muscle tissues have an electric gradient which can reverse when stimulated
-contraction: all muscle tissues have the ability to contract, or shorten
-elongate: all muscle tissue share the capacity to elongate, or relax
Skeletal muscles
-Voluntary muscles that work in pairs to move various parts of the skeleton
-skeletal muscles are composed of muscle fibers (cells) that are bound together in parallel bundles
-skeletal muscles are also known as striated muscle due to their striped appearance under a microscope
Smooth muscle
-Involuntary muscles that are found in the walls of internal organs such as the stomach, intestines, and blood vessels
-smooth muscle tissues or visceral tissue is non-striated
-smooth muscle cells are shorter and wider than skeletal muscle fibers
-smooth muscle tissue is also found in sphincters or valves that control various openings throughout the body
Cardiac muscle
Tissue is involuntary muscle that is found only in the heart
-like skeletal muscle cells, cardiac muscle cells are also striated
Muscular system
-only skeletal muscle interacts with the skeleton to move the body
-when they contract, the muscles transmit force to the attached bones
-working together, the muscles and bones act as a system of levers which move around the joints
-a small contraction of a muscle can produce a large movement
-a limb can be extended and rotated around a joint due to the way the muscles are arranged
Skeletal muscle contraction
-Skeletal muscles consist of numerous muscle fibers
-each muscle fiber contains a bundle of myofibrils, which are composed of multiple repeating contractile units called sarcomeres
Myofibrils
-Myofibrils contain two protein microfilaments: a thick filament and a thin filament
-the thick filament is composed of the protein myosin
-the thin filament is composed of the protein actin
-the dark bands (Striations) in skeletal muscles are formed when thick and thin filaments overlap
-light bands occur where the thin filament is overlapped
-skeletal muscle attraction occurs when thin filaments slide over the thick filaments, shortening the sarcomere
Action potential
-When an action potential (electrical signal) reaches a muscle fiber, calcium ions are released
-according to the sliding filament model of muscle contraction, these calcium ions bind to the myosin and actin, which assists in the binding of the myosin heads of the thick filaments to the actin molecules of the thin filaments
-adenosine triphosphate released from glucose provides the energy necessary for the contraction
Male reproductive system
-The functions of the male reproductive system are to produce, maintain, and transfer sperm and semen into the female reproductive tract and to produce and secrete male hormones
-The external structure includes the penis, scrotum, and testes
-the penis which contains the urethra, can fill with blood and become erect, enabling deposition of semen and sperm into the female reproductive tract during sexual intercourse
-the scrotum is a sack of skin and smooth muscle that houses the testes and keeps the testes at the proper temperature for spermatogenesis
-the testes, or testicle, are the male gonads, which produce sperm and testosterone
-the internal structure includes the epididymis, vas deferens, ejaculatory ducts, urethra, seminal vesicles, prostate gland, and bulbourethral glands
-that epididymis stores the sperm as it matures
-mature sperm move from the epididymis to the vas deferens to the ejaculatory duct
-the seminal vesicles secrete alkaline fluids with proteins and mucus into the ejaculatory duct, also
-the prostate gland secretes a milky white fluid with proteins and enzymes as part of the semen
-the bulbourethral., or Cowper’s, glands secrete a fluid into the urethra to neutralize the acidity in the urethra -additionally, the hormones associated with the male reproductive system include follicle-stimulating hormone, which stimulates spermatogenesis, luteinizing hormone, which stimulates testosterone production, and testosterone, which is responsible for the male sex characteristics.
Male reproductive system
Female Reproductive System
-The functions of the female reproductive system are to produce ova (oocytes, or egg cells), transfer the ova to the fallopian tubes for fertilization, receive the sperm from the male, and to provide a protective, nourishing environment for the developing embryo
-the external portion of the female reproductive system includes the labia majora, labia minors, Bartholin’s glands and clitoris
-the labia major and the labia minora enclose and protect the vagina
-the Bartholin’s glands secrete a lubricating fluid
-the clitoris contains erectile tissue and nerve endings for sensual pleasure
-the internal portion of the female reproductive system includes the ovaries, fallopian tubes, uterus, and vagina
-the ovaries, which are the female gonads, produce the ova and secrete estrogen and progesterone
-the fallopian tubes carry the mature egg toward the uterus
-fertilization typically occurs in the fallopian tubes
-if fertilized, the egg travels to the uterus, where it implants in the uterine wall
-the uterus protects and nourishes the developing embryo until birth
-the vagina is a muscular tube that extends from the cervix of the uterus to the outside of the body
-the vagina receives the semen and sperm during sexual intercourse and provides a birth canal when needed
Female reproductive system
