Integumentary System_Zoology

• In biology, the term “integument” refers to a network of properties that make up an organism’s covering.
• The integument defines the boundaries of the organism’s body, insulating it from its surroundings and shielding it from outside elements.
• The integument, for example, is any secretion made by an organism to cover itself or the cell membrane in unicellular organisms like bacteria or protozoans.
• Integument comes from the Latin word “integumentum,” which means a covering.
• In anatomy, the largest organ in humans and vertebrates is the integument.
• It carries out a variety of essential tasks, such as insulation, thermoregulation, secretion, sensation, and protection against viruses, chemicals, and abrasive damage.
• The exterior cell wall of almost all bacteria helps to protect them by keeping the cells rigid and in shape.
• The cell membrane and any covering it secretes constitute unicellular organisms’ integuments. The exterior cell wall of almost all bacteria helps to protect them by keeping the cells rigid and in shape.
• Multicellular invertebrates only have one outer layer of epithelial cells. These cells can create a wide range of surface coverings, from the mucous coat of cnidarians (sea anemones, polyps, and jellyfish) to the hard cuticle of insects.
• Arthropods such as insects, crustaceans, and spiders, a multilayered and hardened integument creates an exoskeleton to which muscles are linked. These rigid structures.
• In humans, the integumentary system includes the skin, a thickened, keratinised epithelium consisting of several cell layers and is largely water-resistant.
• The integumentary system also consists of the hair and nails, which are skin-derived organs. They protect the body from danger, detect its surroundings, and support its homeostasis.
• The largest and heaviest organ of the body is the skin.
• Skin - thickened keratinised epithelium consist of several layers and is water resistant. Also the largest and heaviest organ of the body.
• Epidermis - outermost layer, thin and continuously sheds dead skin cells.
• Dermis - middle layer, has sweat glands, blood vessels, nerves, and hair follicles.
• Hypodermis (subcutaneous layer) - innermost layer, compromise connective tissue and fat that connects skin to muscles, it also provides insulation and cushion.
• Stratified Squamous Epithelial Tissue - made up of multiple layers of squamous cells, found on the surface of the skin and lining of mouth, esophagus, anus, vagina, cervix, urethra, and ducts of mammary glands.
• Function of Skin

  • physical barrier and first line of defence against illness brought by microorganisms.
  • controls body temperature, remove waste, protect body from disease/injuries.
• Glands - cells that function as a discharge unit of substances (sweat and oil).
• Two Types of Glands

  • Endocrine Glands
  • Exocrine Glands
• Endocrine Glands - lacks duct system, immediately release substance into blood.
• Exocrine Glands - with ducts, enables to discharge chemicals onto epithelial surface.
• Types of Exocrine Glands

  • Apocrine Sweat Glands
  • Eccrine Sweat Glands
  • Sebaceous Glands
  • Ciliary Glands
  • Ceruminous Glands
  • Mammary Glands
• Apocrine Sweat Glands - produces odorous perspiration, often develop in genital region and armpits, do not cool.
• Eccrine Sweat Glands - cools body and excrete waste by water secretion. It is a primary coiling tubelike glands found all over the body that produces clear, little to no oily and odorless perspiration.
• Sebaceous Glands - release sebum, an oily material that hydrates and protect skin.
• Ciliary Glands - modified apocrine sweat glands found in eyelids, lubricates the eye and keep it clean.
• Ceruminous Glands - ear canal glands that also modified apocrine glands which produces ear wax (protect from water, a sticky material).
• Mammary Glands - front of chest wall include two mammary glands, it produces milk for newborn.
• Hair - a thin like structures, generally pigmented which gives color and made by protein called keratin.
• Except palms and soles of feet, entire body is covered with hair.
• Hair provide defense against UV rays, wound, and extreme temperatures, have sensation since it have nerve endings.
• Nails - a hard bony structure that protects fingers and toes. It developed from base of nail bed and made by protein called keratin.
• Nails promote fine motor functions like picking up small things and protect fingertips from harm.
• Cnidarians - provides all essential components of integument, it contains pigment cells, gland cells, stinging cells, sensory cells with projecting hairs, and epithelial cells (some are contractiles).
• Protozoans - range in hardness from soft forms like amoeba to form with cuticle that is made of cellulose or protein like that of monocystis (plantlike flagellates).
• Flukes - have thick integument covered in sensory papillae, microvili, an apical membrane thrown in pits and ridges and many spines.
• Roundworms - have epicuticle that is thick and flexible, and 3 recognizable zones.
• Arthropods - have most complex exoskeleton structures (insect and crustaceans).