Digestive and Respirtory

Cards (36)

  • Digestive system
    System responsible for breaking down food into nutrients that can be absorbed and used by the body
  • Key components of the digestive system
    • Saliva
    • Esophagus
    • Stomach
    • Small intestine
    • Large intestine
    • Pancreas
    • Liver
    • Gallbladder
  • Saliva
    • Contains amylase which digests starches (carbohydrates)
  • Movement of food through the digestive system
    1. Food mixture (bolus) moves down the esophagus via peristalsis
    2. Food is churned with acid in the stomach and called chyme
    3. Chyme enters the small intestine
    4. Digestion is completed in the small intestine
    5. Mixture enters the large intestine
  • Stomach
    • Acid kills bacteria and starts digestion of proteins and continues digestion of starches
  • Small intestine
    • First section is the duodenum where chyme is neutralized
    • Digestion is completed and digested products are absorbed from the ileum
  • Large intestine
    • Water and vitamins are reabsorbed
    • Anaerobic bacteria can ferment undigested polysaccharides to produce energy
  • Pancreas
    • Secretes amylase, trypsin and lipase into the small intestine
  • Liver
    • Secretes bile to emulsify lipids
  • Gallbladder
    • Stores bile, which is not an enzyme and breaks down large lipid molecules
  • Layers of the small intestine
    • Serosa
    • Longitudinal muscles
    • Circular muscles
    • Submucosa
    • Mucosa
  • Villi
    • Increase the surface area of the small intestine for absorption
  • Digestion in the small intestine
    1. Food is broken down into monomers
    2. Pancreas and intestinal wall secrete enzymes into the lumen
    3. Pancreatic enzymes have an optimal pH of neutral to alkaline
    4. Enzymes include amylase, endopeptidases, lipases, phospholipases, nucleases, maltase, lactase, exopeptidases, and dipeptidases
  • Intestinal villi
    • Increase surface area for absorption
    • Goblet cells produce mucus
    • Capillary network and lacteal carry away absorbed nutrients
  • Products directly absorbed by villi
    • Bases and phosphates from nucleic acids
    • Fatty acids and glycerol
    • Amino acids
    • Monomeric carbohydrates
  • Methods of absorption
    1. Substances move from lumen into epithelial villi
    2. Amino acids and monosaccharides move from villi into capillaries, monoglycerides move into lacteals
    3. Absorption methods: simple diffusion, facilitated diffusion, active transport, pinocytosis
  • Starch digestion in the small intestine
    1. Amylase breaks down starch into maltose, maltotriose and dextrins
    2. Maltase, glucosidase and dextrinase break down these into glucose which is absorbed
  • Transport of absorbed nutrients
    All absorbed monomers are transported via the hepatic portal vein to the liver, then enter the general circulation
  • Ventilation
    Breathing in and out
  • Ventilation
    • Maintains oxygen and carbon dioxide concentration gradients
    • Replaces low oxygen air with high oxygen air
  • Gas exchange
    • Depends on oxygen and carbon dioxide concentration gradients
    • Facilitated by thin alveolar walls and moisture
  • Types of alveolar cells
    • Type 1 pneumocytes (thin for gas exchange)
    • Type 2 pneumocytes (secrete surfactant)
  • Ventilation mechanism
    1. Thorax expands during inspiration, decreasing pressure and drawing air in
    2. Thorax contracts during expiration, increasing pressure and forcing air out
  • Muscles involved in ventilation
    • External and internal intercostal muscles are antagonistic
    • Diaphragm contracts to increase thoracic volume
  • Lung cancer
    Most common form of cancer, mainly caused by smoking, results in shortness of breath, cough, chest pain
  • Emphysema
    Caused by long-term exposure to cigarette smoke, results in inflammation, narrowing of airways, and breakdown of alveolar walls
  • Alveoli
    • Site of gas exchange
    • Type 1 pneumocytes provide large surface area
    • Type 2 pneumocytes secrete surfactant
  • Blood pH regulation

    • Buffers in blood plasma and tissue fluids maintain pH close to neutral
    • CO2 lowers pH, forming carbonic acid and hydrogen ions
  • Adult hemoglobin
    • Composed of 2 alpha and 2 beta chains, each with a heme group containing iron
  • Fetal hemoglobin
    • Has 2 alpha and 2 gamma peptides, allowing higher oxygen affinity than adult hemoglobin
  • Myoglobin
    Protein used to bind oxygen in muscles, has higher affinity for oxygen than hemoglobin
  • Oxygen transport in blood
    Oxygen binds to hemoglobin in the lungs, causing an allosteric change that increases oxygen binding affinity
  • Carbon dioxide transport in blood
    CO2 dissolves in plasma, binds to hemoglobin as carbaminohemoglobin, or is converted to carbonic acid and bicarbonate ions
  • Bohr shift
    Increased oxygen concentration decreases hemoglobin's affinity for oxygen
  • Gas exchange during exercise
    Increased tissue demand for oxygen is met by increased rate and depth of breathing, controlled by the respiratory control centre
  • Gas exchange at high altitude
    Lower oxygen concentration leads to decreased hemoglobin affinity for oxygen, reducing oxygen supply to tissues