gas exchange

• Asexual reproduction


  A single parent splits, buds, or fragments to give rise to two or more offspring that have hereditary traits identical with those of the parent
• Types of asexual reproduction

  • Fission
  • Budding
  • Fragmentation
  • Regeneration
• Fission


  • The separation of a parent into two or more individuals of approximately equal size
• Fission


  • Paramecium
• Budding


  • New individuals arise from outgrowths of existing ones
• Budding


  • Cnidarians (hydra)
• Fragmentation


  • The breaking of the body into several pieces, some or all of which develop into complete adults
• Fragmentation


  • Flatworms, planaria
• Regeneration


  • The regrowth of lost body parts; usually accompanied with fragmentation
• Regeneration


  • Lizard
• Types of fertilization


  • Internal fertilization
  • External fertilization
• Internal fertilization


  The male generally delivers sperm cells directly into the body of the female. Her moist tissues provide the watery medium required for movement of sperm.
• Internal fertilization


  • Most terrestrial animals, some fishes and some other aquatic animal
• External fertilization


  Mating partners usually release eggs and sperms into the water simultaneously.
• External fertilization


  • Many fish, amphibians, and other sexual aquatic animals (the exceptions are aquatic mammals, sharks, and some other special types of fish)
• Main reproductive systems - Male


  • Male gonad (testis)
  • Sperm duct
  • Penis
• Main reproductive systems - Female


  • Female gonad (ovary)
  • Oviduct
  • Vagina
• Metagenesis


  Also known as 'transformation development', refers to an alternation of asexual and sexual generations.
• Metagenesis


  • Hydrozoan Obelia, a polyp generation gives rise by budding to a generation of medusas. The motile medusas produce gametes and reproduce sexually, giving rise to new generation of polyps.
• Parthenogenesis


  Also known as 'virgin development', is a form of reproduction in which an unfertilized egg develops into an adult animal. This occurs for several generations, after which males develop, produce sperm, and mate with females to fertilize their eggs.
• Parthenogenesis


  • Honeybees. The queen honeybee is inseminated by a male during the "nuptial flight".
• Hermaphroditism


  Means that a single organism produces both eggs and sperm. Although this form of reproduction is still classified as sexual, it is an exception to the generalization that sexual reproduction involves two different individuals.
• Hermaphroditism


  • Earthworm
• Types of physiological reactions in human sexual response

  • Vasocongestion
  • Myotonia
• Vasocongestion


  The filling of a tissue with blood caused by increased blood flow through the arteries of that tissue.
• Myotonia


  Increased muscle tension of both skeletal and smooth muscles.
• Breathing Exercise


  1. Close your mouth and then press your nose

  2. Hold your breath for a few seconds

  3. Run in place for 30 seconds

  4. Sit down and count the number of breaths you take
• Gas Exchange


  The exchange of oxygen and carbon dioxide between an organism and its environment
• Ways animals obtain oxygen

  • From water through moist gill surfaces to blood vessels (e.g., fishes, amphibians)
  • From the air through moist lungs surface to blood vessels (e.g., land snail, land vertebrate)
  • From the air or water through a thin, moist body wall of blood vessels (e.g., earthworm)
  • From the air through spiracles (opening on the thorax) or a tracheal system to a system of ducts to the tissues (e.g., insects)
  • From the air or water through the moist surface directly into the body (e.g., amoeba, flatworm)
• Respiratory System


  The system that exchanges oxygen and carbon dioxide between the air and the cells
• In simple animals, exchange of gases directly occurs with the environment, while in some animals like mammals, breathing is done through the body's nasal passages
• The general body surface of most animals lacks sufficient area to exchange gases for the whole organism
• The solution is a respiratory organ that is extensively folded or branched, thereby enlarging the available surface area for gas exchange
• Air


  A respiratory medium with plentiful O2
• Water


  A respiratory medium with much less oxygen and greater density and viscosity, making gas exchange more challenging
• The respiratory surfaces (organs) where gas exchange with the respiratory medium occurs must be moist, thin, and large enough to supply the whole body
• Skin system


  • Animals that live in moist environments like worms and amphibians used their moist body surface to breathe in oxygen
  • Capillaries or tiny vessels lie just below the skin of worms to facilitate gas exchange between the external environment and the circulatory system
  • The skin of frogs is made up of very thin tissues, allowing smooth exchange of gases
• Gills system


  • Fish and other aquatic animals use their gills to take up the dissolved oxygen from water
  • Gills are thin tissue filaments that are highly branched and folded
  • When water passes over the gills, the dissolved oxygen in water rapidly diffuses across the thin membranes of the gills into the bloodstream
  • Carbon dioxide in the bloodstream of the animals leaves through the gills
• Tracheal system


  • Insects, such as grasshoppers and spiders, use their tracheae to facilitate gas exchange
  • Tracheae consist of air tubes called spiracles forming network in the bodies of insects
  • Spiracles connect to the tubular network allowing oxygen to pass into the body and regulate the diffusion of CO2 and water vapor
• Lung system


  • A pair of organs divided into small chambers filled with capillaries called lungs are found inside the cavity of land animals such as humans
  • The tube that connects the nose and mouth to the lungs is called trachea
  • The trachea divides into two main bronchi (the left and right) which further subdivides into bronchioles
  • The tip of each bronchiole is called alveolus wherein actual gas exchange occurs
  • The diaphragm, a large muscle that aids in breathing by moving up and down
  • The rib cage encloses the lungs and protects the respiratory organs and the heart
  • Air is inhaled through the nasal cavity and crosses the surfaces of the mucous membrane
  • From the nasal cavity, air passes through the pharynx and the larynx to the trachea
  • Particulates in the air are removed in the nasal passages preventing damage to the trachea and lungs