Animals: Form and Functions [BIOLOGY]

• Types of Animal Tissues

  • Epithelial tissues
  • Connective tissues
  • Muscle tissues
  • Nervous tissues
• Connective tissues

  • Loose connective tissues
  • Fibrous connective tissues
  • Adipose tissue
  • Cartilage
  • Bone
  • Blood
• Muscle tissues

  • Skeletal muscles
  • Cardiac muscles
  • Smooth muscles
• Organ Systems

  • Integumentary System
  • Digestive System
  • Respiratory System
  • Circulatory System
  • Immune System
  • Lymphatic System
  • Urinary System
  • Endocrine System
  • Reproductive System
  • Nervous System
  • Musculoskeletal System
• Epithelial tissues

  Epithelial tissues or epithelia are sheets of closely packed cells that cover the surface of the body and line the internal organs and cavities. The closely-knit cells form a protective barrier but may still allow fluid exchange on the other side. The side of the epithelium which faces the outside environment or the inside of a tube or passageway is referred to as the apical surface.
• Epithelial tissues

  Epithelial tissues are named according to the number of cell layers or the shape of the cells on their apical surface: simple epithelium has a single layer of cells while multiple layers make up a stratified epithelium. Based on shape, the cell can be squamous (flat and looks like fried eggs), cuboidal (like dice), or columnar (brick-like). The combination of the number of layers and cell shapes tells us of their function.
• Connective tissues

  Connective tissues are cells scattered throughout a matrix. The cells produce and secrete the matrix which usually consists of a web of fibers embedded in a liquid, jelly, or solid
• Connective tissues

  Loose connective tissues are the most widespread in the body and are made up of a matrix with a loose weave of fibers suspended in a watery fluid. Many of the fibers are made of collagen while others are elastic, making the tissue resilient as well as it is strong. This tissue binds epithelia to underlying tissues and holds organs in place
• Connective tissues

  Fibrous connective tissues have a matrix made up of densely packed collagen, and this maximizes strength. This tissue forms our tendons, which attach to bone, and ligaments, which connect bones at joints
• Connective tissues

  Adipose tissue stores fat in large, closely packed adipose cells held in a very sparse matrix of loose fibers and fluid. This tissue pads and insulates the body as well as stores energy in the form of fat
• Connective tissues

  Cartilage forms a strong but flexible skeletal material. Its matrix is made from collagen fibers embedded in a rubbery material. Cartilages commonly surround the ends of bones, providing shock-absorption; support the ears and nose; and lastly, provide cushioning disks between our vertebrae
• Connective tissues

  Bone is made up of collagen fibers embedded in a hard mineral substance made of calcium, magnesium, and phosphate. This combination of materials makes our bones strong without being brittle.
• Connective tissues

  Blood transports substances throughout the body and thus functions differently from other connective tissues. Its matrix is called the plasma and suspended in it are the different types of blood cells
• Muscle tissues

  Muscle tissues are the most abundant in nearly all animals. It’s made of long cells called muscle fibers, each having contractile proteins
• Muscle tissues

  Skeletal muscles are attached to bones by tendons and are responsible for voluntary movements of the body. The cells are arranged in a way that they appear striped or striated
• Muscle tissues

  Cardiac muscles are the contractile tissues of the heart. It is striated like the skeletal muscle but it is involuntary or cannot be consciously controlled. Cardiac muscles are branched, interconnected at special junctions called intercalated disks that help relay signals to contract from cell to cell during a heartbeat
• Muscle tissues

  Smooth muscles lack striations. They are found in the walls of the digestive tract, arteries, and other internal organs. They are responsible for involuntary body activities such as the movement of food in the digestive system
• Nervous tissues

  Nervous tissues sense stimuli and help transmit information. They are found in the brain, spinal cord, and the nerves throughout the body.
• Nervous tissues

  The structural unit of the tissue is a nerve cell, or a neuron, which is specialized for conducting electric nerve impulses. A neuron is composed of a cell body, which contains the nucleus and other organelles; and extensions that may receive a nerve impulse from other neurons, referred to as the dendrite, or those that transmit signals to other neurons, referred to as axons, or effector cells such as muscle cells that respond to the stimuli.
• The integumentary system protects against physical injury, infection, excessive heat or cold, and drying out
• The digestive system ingests and digests food, absorbs nutrients, and eliminates undigested food material
• The respiratory system is responsible for exchanging gases with the environment, supplying the blood with O2, and disposing of CO2
• The circulatory system delivers oxygen (O2 ) and nutrients to the cells of the body and transports carbon dioxide (CO2 ) to the lungs and metabolic wastes to the kidneys
• Although technically not an organ system, the immune system functions in defending against infections and cancer.
• The lymphatic system returns excess body fluids to the circulatory system and functions as part of the immune system.
• The urinary system removes waste products from the blood and excretes urine. It also regulates the chemical and water balance of the blood.
• The endocrine system secretes hormones that regulate body activities, thus maintaining homeostasis
• The reproductive system produces the sex cells and sex hormones with the female system supporting the developing embryo and producing milk.
• The nervous system coordinates body activities by detecting stimuli, integrating information, and directing responses
• The skeletal system supports the body and protects the organs. It provides a framework for muscle movement. On the other hand, the muscular system moves the body, maintains posture, and produces heat.