General Biology

• Calorie


  Unit of energy that indicates the amount of energy contained in food
• Carbohydrates


  Serve as a major energy source for the cells in the body, usually obtained from grains, cereals, breads, fruits, and vegetables, contain 4 Calories per gram
• Proteins


  Can be used as an energy source but the body mainly uses these as building materials for cell structures and as enzymes, hormones, parts of muscles, and bones, come from dairy products, poultry, fish, meat, and grains, contain 4 Calories per gram
• Fats


  Used to build cell membranes, steroid hormones, and other cellular structures, used to insulate nervous tissue, serve as an energy source, contain certain fat-soluble vitamins, obtained from oils, margarine, butter, fried foods, meat, and processed snack foods, contain 9 Calories per gram
• Essential Nutrients

  • Essential amino acids
  • Essential fatty acids
  • Vitamins
  • Trace Elements or Minerals
• Essential amino acids


  Needed for synthesis of proteins and enzymes, 8 that could not be synthesized by humans: lysine, tryptophan, threonine, methionine, phenylalanine, leucine, isoleucine and valine
• Essential fatty acids


  Used for making special membrane lipids, an example is linoleic acid in humans
• Fat-soluble Vitamins


  • A, D, E, K
• Water-soluble Vitamins


  • B, B2, B3, B12, C
• Trace Elements or Minerals


  Inorganic nutrients needed by the body in minute amounts, form part of enzymes, body tissues, and body fluids, examples include: iodine, cobalt, zinc, molybdenum, manganese, selenium
• Phagocytosis


  Engulfment of organic fragments or big particles, eg. Pseudopod formation in Amoeba
• Pinocytosis


  Uptake of extracellular fluid by a cell using small vesicles derived from the plasma membrane
• Receptor-mediated endocytosis


  Relies on membrane receptor recognition of specific solutes which are then taken up by the cell via receptor-coated pits
• Food uptake in cells via three types of endocytosis


  • Phagocytosis
  • Pinocytosis
  • Receptor-mediated endocytosis
• Direct feeders


  Animals that live in or on their food source, examples: earthworms that feed through the soil where they live in, caterpillars that eat through the leaves where they live on
• Filter feeders


  Include many aquatic animals which draw in water and strain small organisms and food particles present in the medium, examples: whales and coelenterates
• Parasitic feeders


  Suck fluids containing nutrients from a living host, examples: mosquitoes, leeches, head lice, aphids
• Predatory feeders


  Eat relatively large chunks of food and have adaptations like jaws, teeth, tentacles, claws, pincers, etc. that help in securing the food and tearing it to pieces, examples: snakes, dogs, man
• Obesity


  A complex disease involving an excessive amount of body fat, results from a combination of inherited factors, combined with the environment and personal diet and exercise choices
• Vitamin C can help you fight a cold faster or ease your cold symptoms if you were taking it prior to getting sick
• Vitamin D can also protect you from respiratory infection, it significantly decreases the chance of respiratory tract infections
• Zinc helps shorten the length of rhinovirus colds, it also helps symptoms—nasal congestion, nasal drainage, sore throat, and cough—resolve sooner
• Lactose, or milk sugar, is a disaccharide composed of glucose and galactose
• Decreased lactase activity is associated with a condition known as lactose intolerance
• If a person with lactose intolerance drinks milk or eats dairy products, diarrhea may result
• Bacteria in the large intestine ferment lactose to gas and organic acids, leading to bloating and flatulence
• Gas exchange or respiration is a process wherein the oxygen delivers to the cells of the body's tissues and removes carbon dioxide, a cell waste product
• Main structures of the human respiratory system

  • Nasal cavity
  • Trachea
  • Lungs
• Oxygen is needed in tissues for aerobic cellular respiration to occur and extract ATP from food
• Carbon dioxide must be released to prevent physiological pH in tissues from being very acidic
• Direct Diffusion


  Diffusion across the outer membrane is sufficient to meet the oxygen needs of small multicellular organism
• Skin and Gills


  • Amphibians use their skin as a respiratory organ
  • Gills are thin tissue filaments that are highly branched and folded
• Tracheal System


  Insects have a highly specialized type of respiratory system called the tracheal system, which consists of a network of small tubes that carries oxygen to the entire body
• Mammalian System


  • Air is warmed and humidified in the nasal cavity
  • Air then travels down the pharynx, through the trachea, and into the lungs
  • In the lungs, air passes through the branching bronchi, reaching the respiratory bronchioles, which house the first site of gas exchange
  • The respiratory bronchioles open into the alveolar ducts, alveolar sacs, and alveoli
  • There are so many alveoli and alveolar sacs in the lung, the surface area for gas exchange is very large
  • Protective mechanisms are in place to prevent damage or infection, including hair and mucus in the nasal cavity that trap dust, dirt, and other particulate matter before they can enter the system
• Obstructive diseases


  • Emphysema is a disease that causes shortness of breath, arising from smoking tobacco; the walls of the alveoli are destroyed, decreasing the surface area for gas exchange
  • Asthma is a disease in which inflammation is triggered by environmental factors; the airways narrow and swell and may produce extra mucus; inflammation obstructs the airways
• Those with obstructive diseases have large volumes of air trapped after exhalation and breathe at a very high lung volume to compensate for the lack of airway recruitment
• Trachea


  • Funnel the inhaled air to the lungs and the exhaled air back out of the body
  • Divides into the two primary bronchi at the mid-thorax
  • Has mucus-producing goblet cells and ciliated epithelia
  • The cilia propel foreign particles trapped in the mucus toward the pharynx
  • The forced exhalation helps expel mucus when we cough
• Lungs


  • The right lung is larger and contains three lobes, whereas the smaller left lung contains two lobes
  • The muscular diaphragm, which facilitates breathing, is located below the lungs and marks the end of the thoracic cavity
• Air is diverted into smaller and smaller passages, or bronchi


  1. Air enters the lungs through the two primary bronchi

  2. Each bronchus divides into secondary bronchi, then into tertiary bronchi, which in turn divide, creating smaller and smaller diameter bronchioles as they split and spread through the lung
• Alveoli


  • Made of thin-walled parenchymal cells, typically one-cell thick, that look like tiny bubbles within the sacs
  • In direct contact with capillaries of the circulatory system
  • Oxygen will diffuse from alveoli into the blood and be distributed to the cells of the body
  • Carbon dioxide that was produced by cells as a waste product will diffuse from the blood into alveoli to be exhaled