GAS EXCHANGE

• Gas exchange


  The biological process through which gases are transferred across cell membranes to either enter or leave the blood
• Function of gas exchange

  • Allows oxygen to travel into cells for respiration whilst also removing carbon dioxide, which is a waste substance made by the process of respiration
  • Respiration is a vital process that involves releasing energy from glucose
• Gas exchange in the lungs

  1. Trachea

  2. Bronchus

  3. Bronchiole

  4. Alveoli

  5. Intercostal muscles

  6. Diaphragm
• The connective tissue includes elastic fibers that allow alveoli to stretch and expand as they fill with air during inhalation. During exhalation, the fibers allow the alveoli to spring back and expel the air. This substance prevents the alveolar walls from collapsing and sticking together when air is expelled. Other cells in alveoli include macrophages, which are mobile scavengers that engulf and destroy foreign particles that manage to reach the lungs in inhaled air
• External respiration


  Occurs as a function of partial pressure differences in oxygen and carbon dioxide between the alveoli and the blood in the pulmonary capillaries
• Internal respiration


  Also occurs as simple diffusion due to a partial pressure gradient. However, the partial pressure gradients are opposite of those present at the respiratory membrane
• Cellular respiration


  The process by which organisms combine oxygen with foodstuff molecules, diverting the chemical energy in these substances into life-sustaining activities and discarding, waste products, carbon dioxide, and water
• Steps of cellular respiration

  1. Glycolysis

  2. Pyruvate oxidation

  3. Citric acid cycle

  4. Oxidative phosphorylation
• Osmosis


  When solvent (H2O) molecules pass through a semi-permeable membrane from less concentrated to more concentrated solution
• Osmolarity


  The ratio of solute
• Osmoregulation


  Regulation of the osmolarity of an organism's body fluids to maintain homeostasis
• Hypertonic


  Blood with too low water potential. Too much water will move from the blood into the cells by osmosis, causing cells to burst
• Hypotonic


  Blood with too high-water potential. Too much water will move from the blood into the cells by osmosis, causing cells to burst
• Isotonic


  The concentration in the blood and outside the blood is the same
• Types of osmoregulation


  • Osmoconformers
  • Osmoregulators
• Osmoregulation in different organisms

  • Freshwater fish
  • Marine fish
  • Human body
• Nephrons


  Functional unit of the kidney responsible for filtering blood and producing urine
• Parts of a nephron

  • Glomerulus
  • Proximal convoluted tubule
  • Descending loop of Henle
  • Ascending loop of Henle
  • Distal tubule
  • ADH (Antidiuretic hormone)
  • Collecting duct
• Asexual reproduction


  A mode of reproduction in which a new offspring is produced by a single parent. The new individuals produced are genetically and physically identical to each other
• Reproduction


  The process of producing individuals of the same kind. Most organisms reproduce by mating, which increases the genetic variability of the organism
• Types of reproduction


  • Sexual reproduction
  • Asexual reproduction
• Sexual reproduction


  The combination of reproductive cells from two individuals to form genetically unique offspring
• Hermaphroditism


  Occurs in animals in which one individual has both male and female reproductive systems
• Reproduction


  The process of producing individuals of the same kind
• Most organisms reproduce by mating, which increases the genetic variability of the organism
• Gonads


  The male and female reproductive organs that produce gametes
• Zygote


  The single cell formed by the fusion of the male and female gametes
• Types of Reproduction


  • Sexual Reproduction
  • Asexual Reproduction
• Sexual Reproduction


  • The combination of reproductive cells from two individuals to form genetically unique offspring
  • The nature of the individuals that produce the two kinds of gametes can vary, having for example separate sexes or both sexes in each individual
  • Sex determination, the mechanism that determines which sex an individual develops into, also can vary
• Hermaphroditism


  When one individual has both male and female reproductive systems
• Hermaphroditic organisms


  • Earthworms
  • Slugs
  • Tapeworms
  • Snails
• Fertilization


  The fusion of a sperm and an egg to form a single nucleus
• Types of Fertilization


  • Internal Fertilization
  • External Fertilization
• Internal Fertilization


  The male directly deposits sperm in the female during mating, or the male deposits sperm in the environment which the female picks up to deposit in her reproductive tract
• Offspring production in internal fertilization

  • Oviparity
  • Ovoviviparity
  • Viviparity
• Oviparity


  The fertilized eggs are laid outside, where they receive nourishment from the yolk
• Ovoviviparity


  The fertilized eggs are retained in the female's body where they receive nourishment from the yolk, and are laid right before they hatch
• Viviparity


  The offspring are born directly instead of hatching from eggs, and receive nutrition from the mother
• External Fertilization


  Occurs in aquatic environments where both eggs and sperm are released into the water, and fertilization takes place after the sperm reaches the egg
• Asexual Reproduction


  Occurs in prokaryotic microorganisms and many eukaryotic, single-celled, and multi-celled organisms