sci

• Biology


  The branch of science that deals with the study of living things
• Living things


  • People
  • Animals
  • Plants
• Food


  One of the most important things that humans need, contains nutrients/substances that the body needs to grow healthy, essential for every living thing
• Digestion


  Breaking down of food into absorbable molecules
• Digestive system


  • Ingestion (taking in food into the mouth)
  • Digestion & absorption (processing of food into a form that will be assimilated into living cells)
  • Excretion (eliminating indigestible substances and certain wastes through the anus)
• Mechanical digestion


  Tearing, grinding and chewing of foods into smaller pieces
• Chemical digestion


  Conversion of food particles into molecules that the body can process/digest through enzymatic reactions
• Digestive system structure


  • Mouth (teeth-tongue-saliva)
  • Pharynx
  • Esophagus
  • Stomach
  • Small intestine
  • Large intestine
  • Rectum
  • Anus
• Mouth


  • Mechanical and chemical digestion take place, teeth mechanically break down food, tongue mixes food with saliva (contains amylase to break down starch)
• Pharynx


  Connects the mouth and nose to the esophagus, allowing it to be part of two body systems
• Esophagus


  • Secretes mucus, connects the pharynx to the stomach, moves food from the throat to the stomach using peristalsis (involuntary contraction and relaxation of muscles)
• Peristalsis


  Movement of food from throat to stomach
• Anti-peristalsis


  Movement of food from stomach to throat, usually happens when vomiting
• Stomach


  • J-shaped muscular bag that stores food, breaks it down into tiny pieces, mixes food with digestive juices containing enzymes to break down proteins and lipids, produces chyme (thick, semifluid mass)
• Small intestine


  • Roughly 7 meters long, lining has fingerlike projections called villi to increase surface area, villi are covered in microvilli which further increases surface area for absorption, absorbs 80% of ingested water, vitamins, minerals, carbohydrates, proteins, lipids, secretes digestive enzymes
• Large intestine


  • About 1.5 meters long, accepts what small intestine doesn't absorb, separates liquids, salts, and unnecessary wastes in the form of poop, has four parts: cecum, colon, rectum, and anal canal, absorbs more water, concentrates wastes
• Rectum


  Short term storage which holds the feces before it is expelled
• Anus


  The final outer part of the digestive system, where the feces and waste are excreted
• Accessory digestive glands


  • Salivary glands
  • Liver
  • Pancreas
• Salivary glands


  • 6 glands (2 submaxillary, 2 parotid, 2 sublingual) that secrete saliva containing the starch-digesting enzyme salivary amylase or ptyalin, which changes starch into maltose
• Liver


  • Largest gland in the body, produces bile which helps digest fat, filters out toxins and waste including drugs, alcohol, and poisons
• Gall bladder


  Stores bile from the liver, releases it into the small intestine
• Pancreas


  • Produces digestive enzymes to digest fats, carbohydrates, and proteins, produces insulin to regulate blood sugar
• Disorder


  Disturbance of normal function of the body
• Digestive system disorders


  • Diarrhea
  • Constipation
  • Irritable Bowel Syndrome (IBS)
  • Obesity
  • Lactose intolerance
• Diarrhea


  Characterized by loose bowel, accompanied by vomiting, caused by eating contaminated foods which infect the digestive track
• Constipation


  Characterized by hard, dry stool, and bowel movement that are infrequent or hard to pass
• Irritable Bowel Syndrome (IBS)


  Person alternately experiences diarrhea and constipation, caused by stress, allergies, insufficient intake of dietary fibers
• Obesity


  Abnormal accumulation of fat in the body, a metabolic disorder that occurs when a person takes in more calories than the amount they use
• Lactose intolerance


  Inability to absorb sugar, caused by deficiency in the enzyme lactase which breaks down sugar
• Disease


  Impairment of normal functioning of parts of the body, manifested by particular signs and symptoms
• Digestive system diseases


  • Gastroesophageal Reflux Disease (GERD)
  • Peptic ulcer
  • Gastritis
  • Colon cancer
• Gastroesophageal Reflux Disease (GERD)


  Ingested food leaks back from stomach to esophagus, the stomach acid that flows back can irritate the lining of the esophagus, happens when esophageal sphincter doesn't close well, results in severe heartburn, difficulty swallowing, and reflux
• Peptic ulcer


  Painful lesion of stomach and small intestine
• Gastritis


  Inflammation of the lining of the stomach
• Colon cancer


  Uncontrolled growth of abnormal cells in the large intestine
• Walther Flemming


  • First to observe chromosomes
  • Called it "chromatin"
• Chromatin


  • Greek word: chroma, meaning: color
  • Threadlike structure
• Chromosome


  Soma: bodies, "colored bodies"
• Walter Stanborough Sutton & Theodor Heinrich Boveri

  • Chromosomal theory of inheritance
  • Inherited traits are controlled by genes that are located in the chromosomes which are transmitted to the next generation through sex cells