Muscular System in Animals

Organization of Animal Bodies

• Adult humans have approximately 400 different kinds of cells.
• Tissues are groups of cells of a similar type.
• There are four main types of tissues in vertebrates:
  • Epithelial tissue
  • Connective tissue
  • Muscle tissue
  • Nervous tissue
• Organs consist of two or more tissues that work together to perform a specific function.
• Organ systems are made up of two or more organs that work together to perform a specific function.

The Internal Environment

• The animal body is mainly fluid by weight.
• The intracellular environment is the bulk of the fluid.
• The extracellular environment surrounds cells and carries away waste products.
• The extracellular environment must stay within a narrow range of solute concentration and temperature for cells to survive.

Organ Systems

• Integumentary system: skin, hair, and nails
• Nervous system: brain, spinal cord, sensory organs, and nerves
• Endocrine system: glands and cells that secrete hormones
• Muscular system: individual muscles used to move the body
• Skeletal system: body framework
• Circulatory system: heart and blood vessels
• Lymphatic system: vessels that move fluid from tissues to blood, responsible for immune system
• Respiratory system: lungs and airways
• Digestive system: gut, liver, and pancreas
• Urinary system: kidneys, bladder, and ducts
• Reproductive system: gamete-making organs and ducts

Body Covering

• Protects against injury, abrasion, and disease organisms
• Responds to temperature regulation of body water and temperature
• Has integumentary glands that release secretions that repel or attract
• Functions in concealment, warming, and recognition

Muscular System

• Invertebrate animals:
  • Protozoa: amoeboid movement, can contract or extend the one-celled body in any direction
  • Cnidaria: T-shaped epitheliomuscular cells, can reduce body length and diameter
• Vertebrate animals:
  • Myofibrils: the general structure of muscle fiber, composed of two kinds of filaments: myosin and actin
  • Criteria for classifying muscles:
    • Color: red (resist fatigue) or white (quicker fatigue)
    • Location: somatic (move bone/cartilage) or visceral (control organs, vessels, or ducts)
    • Nervous system control: voluntary or involuntary
    • Embryonic origin
    • Microscopic appearance

Skeletal System

• Invertebrate skeletons:
  • Protozoa: secrete form of skeletons of calcareous, siliceous, or organic substances
  • Porifera: secrete microscopic internal rods (spicules) or fibers of the same kind of materials
  • Cnidaria, echinoderms, mollusks: skeletons mainly lime (CaCo3)
  • Arthropods: exoskeleton of organic materials containing chitin
• Vertebrate skeletons:
  • Cartilaginous endoskeleton (sharks, rays, and embryos)
  • Bony endoskeleton (bony fishes to mammals)
  • Osteoblasts (bone-building cells) and osteoclasts (resorbing cells)

Vertebral Column

• Five regions:
  1. Cervical (neck)
  2. Thoracic (chest and ribs)
  3. Lumbar (lower back)
  4. Sacral (pelvic, joining the hind limb girdle)
  5. Caudal (tail)