BIOLOGY

• Mechanism of actions


  Activations of muscle cells to generate tension or contract for movements
• Skeletal muscles


  • Bundles of muscle fibers
  • Single large cells formed by the fusion of many individual cells during development
• Cytoplasm of skeletal muscle cells

  • Consists of myofibrils
  • Cylindrical bundles of two types of filaments: thick filaments of myosin and thin filaments of actin
  • Each filament is organized as a chain of contractile units called sarcomeres
• Actin


  Thin filament protein found in every type of muscle tissue
• Myosin


  • Thick filament protein found in every type of muscle tissue
  • A type of molecular motor that converts chemical energy released from ATP into mechanical energy used to pull the actin filaments along causing muscle fibers to contract and generate movement
• Actin and myosin interaction

  Work together to generate muscle contractions and movement
• Actin filaments and myosin

  • Responsible for many types of cell movements
  • The most noticeable form of movement is muscle contraction
  • Provide the model for understanding actin-myosin interactions and the motor activity of myosin molecules
• Troponin


  A complex system of three regulatory proteins integral to muscle contraction in skeletal muscles
• Troponin


  • In a relaxed muscle, tropomyosin blocks the attachment site for the myosin cross bridge preventing contraction
  • The binding of myosin to actin causes cross bridge formation and contraction of the muscle
• Mechanism of actions in muscles

  1. Muscle activation: Motor nerve stimulates action potential, sarcoplasmic reticulum releases calcium

  2. Muscle contraction: Calcium binds with troponin, actin and myosin bind and contract using ATP

  3. Recharging: ATP is re-synthesized, allowing actin and myosin to maintain strong binding
• Muscle relaxation


  Stimulation of the nerve stops, calcium is pumped back into the sarcoplasmic reticulum, actin and myosin return to unbound state causing the muscle to relax
• Human skeletons


  The human skeletal system is a complex structure with two distinct divisions composed of fused and individual bones supported by ligaments, tendons, muscles, and cartilage
• Humans are born with over 300 bones, but many of the bones fuse between birth and the end of maturity and remain with the average number of 206 bones in an adult skeleton
• Bones


  • They have three different layers made from three different kinds of cells
  • Their general structure is a combination of a protein called collagen and a molecule called calcium phosphate that weave together to form a strong and lightweight structure
• Types of bone cells

  • Osteoblasts (involved in new bone formation)
  • Osteocytes (mature bone cells that help to mature bones of newborns)
  • Osteoclasts (break down bones and help them to form into correct shapes)
  • Osteoprogenitor (important in repair of fracture)
• Types of bones in the human body

  • Long bones (have long and thin shapes)
  • Short bones (have squat and cubed shapes)
  • Flat bones (have flattened and broad surfaces)
  • Irregular bones (have shapes that do not conform to the above three types)
  • Sesamoid bones (small, flat bones shaped similarly to a sesame seed)
• Axial skeleton


  The one that consists of the skull, trunk, and pelvis bones of the medial core of the body
• Skull


  • Composed of the cranium bones fitting together at joints (sutures) and the facial bones forming the lower front part, consisting of the eye, the ear, the nose, and the mouth cavities
  • Includes the jaw, or mandible, the upper jaw, or maxilla, the zygomatic, or cheekbone, and the nasal bone
• Rib cage (thoracic cage)


  • Forms the thorax (chest) portion of the body and consists of 12 pairs of ribs with costal cartilage and the sternum
• Parts of the axial skeleton

  • Skull (Cranium 8+Facial 14)
  • Ossicles (both ears, 3+3)
  • Hyoid (neck)
  • Thoradic (rib cage)
  • Thorax (sternum)
  • Vertebral column
• Appendicular skeleton


  The portion of the skeleton that consists of 126 bones out of a total of 206 bones and supporting appendages. It includes skeletal elements, limbs, shoulder-supporting girdle, pectoral, pelvic girdle, and joined appendages
• Parts of the appendicular skeleton

  • Shoulder girdle
  • Upper limb
  • Pelvic girdle
  • Lower limb
• Joints


  The parts of the body where two or more bones meet with binding tissues and allow the body to produce movements
• Types of joints

  • Ball and socket joint
  • Hinge joint
  • Condyloid joint
  • Pivot joint
  • Gliding joint
  • Saddle joint
• Ball and socket joint


  • The rounded head of one bone sits in the cup of another bone to permit movement in all directions (shoulder and hip joints)
• Hinge joint


  • Like a door, a joint that opens and closes in one direction along one plane only (elbow and knee joints)
• Condyloid joint


  • Joints that do not rotate but allow movements (finger and jaw)
• Pivot joint


  • Rotary or trochoid joints in which one bone swivels in a ring (ulna, radius, and neck)
• Gliding joint


  • A plane joint that allows only limited movement by slipping smooth surfaces over one another (wrist joint)
• Saddle joint


  • Enables movement back and forth, side to side, and cannot rotate (thumb base)
• Human reproductive system


  The functional male and female reproductive organ systems
• The function of the human reproductive system is to produce and deposit sperms in males and egg cells in females
• Internal fertilization by sexual intercourse

  1. Male inserts penis into female's vagina

  2. Male ejaculates sperm

  3. Sperm pass through cervix into uterus and fallopian tubes

  4. Fertilization of ovum (egg)
• Male reproductive system


  • Contains external genital organs (penis, testes, scrotum)
  • Contains internal parts (prostate gland, vas deferens, urethra)
  • Functions to produce sperm, male sex hormones, and other components of semen
• Penis


  • The male copulatory organ
  • Contains soft, spongy tissue as well as muscles, fibrous tissue, veins, arteries, and the urethra
  • Has urinary and sexual functions
• Erection of penis


  1. Increased flow of blood into corpus cavernosa and corpus spongiosum

  2. Arteries supplying erectile tissues dilate

  3. Penis engorges with blood

  4. Veins through which blood usually exits the penis are compressed, trapping the blood
• Urethra


  • Tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body
  • In males, allows for the passage of urine and expulsion of sperm during ejaculation
• Scrotum


  • Sack of thick skin that protects the testes and controls the temperature of the testes for suitable sperm creation
  • Contains seminal vesicles, vas deferens, testicles, and prostate gland
• Testes


  • Oval pair bodies found in the scrotum
  • Have two primary functions: Production of testosterone and sperm (spermatogenesis)
• Female reproductive system


  • Includes ovaries, fallopian tubes, uterus, vagina, accessory glands, and external genital organs
  • Functions include producing eggs, secreting sex hormones, providing site for fertilization, gestating a fetus, giving birth