Biology P1 miss lowthian

• How are fish adapted for gas exchange?

  Gill filaments stacked in a pile this gives large SA for gas exchange.

  lamellae that increase SA even more

  Also have lots of blood capillaries and thin surface layer to speed up diffusion.
• what is a counter current flow?

  Blood and water flow in opposite direction ensures a large concentration gradient maintained along length of gill If both flowing the same way equilibrium reached and diffusion stops
• how are plants adapted to prevent water loss?

  § Waxy cuticle prevents water evaporating

  § Stomata surrounded by 2 guard cells

  § Guard cells Turgid= pore open to allow gas exchange

  § Guard cells flaccid= pore closed to reduce water loss
• What are features of a terrestrial insect in terms of gas exchange?

  have an exoskeleton made of hard fibrous material for protection and a lipid layer to prevent water

  loss. Insects do not have lungs
• How does the tracheal system of an insect work?

  Spiracles are round, valve like openings running along the length of the abdomen. oxygen and co2 enter and leave via spiracles The trachea attach to these openings, network of internal tubes. The trachea tubes have rings within them to strengthen the tubes and to keep them open. The trachea branch into smaller tubes, deeper into the abdomen of the insect called tracheoles. These extend throughout all the tissues in the insect to deliver oxygen to all the respiring cells
• What are adaptations of an insect for efficient gas exchange?

  1 Large number of fine tracheoles - large surface area

  2 Walls of tracheoles are thin and short distance between spiracles and tracheoles - short diffusion pathway

  3 Use of oxygen and production of carbon dioxide sets up steep diffusion gradients
• What are insects adadptations to prevent water loss?

  1. Insects have a small surface area to volume ratio where water can evaporate from

  2. Insects have a waterproof exoskeleton

  3. Spiracles, where gases enter and water can evaporate from, can open and close to reduce water loss.
• what are the three methods of moving gasses in the tracheal system?

  1. Gas exchange by diffusion as when cells respire, they use up oxygen and produce, creating a concertation gradient from the tracheoles to the atmosphere.

  2. mass transport, in which an insect contracts and relaxes their abdominal muscles to move gases on mass.

  insect is in flight the muscle cells start to respire anaerobically to produce lactate. lowers wp and water moves from tracheoles into cells by osmosis. decreases volume in tracheoles and results in more air from atmosphere is drawn in
• how are plants adapted for co2?

  § Large air spaces

  § Thin cell walls and narrow spaces between cells

  § Irregular packing with large air spaces

  § Large surface area with moist cell wall
• how do gases move in and out of insects lungs?

  Along concentration gradient

  Cells at the end of tracheoles respire and use oxygen and diffuses directly into cells

  The conc of oxygen falls creating a concertation gradient

  
  

  Contraction of muscles in insect can squeeze trachea

  Use rhythmic abdominal movements to move air in and out the spiracles

  
  

  Ends of tracheoles filled with water

  Muscles carry out anaerobic respiration produces lactate reduces water potential at end of tracheoles

  Water moves from tracheoles into muscles cells by osmosis drawing air into tracheoles

  Diffusion of oxygen happens faster in gases than liquids, so the rate of diffusion is quicker
• how to insectes stop themselves drying out?

  Close spiracles

  Waterproof waxy cuticle

  Chitin a material that helps to form waterproof barrier
• what is the process of inspiration?

  external intercostal muscles contract pulling the ribs outward and upward

  The diaphragm contracts causing it to move downward and flattern

  This increases volume of thoracic cavity

  Pressure in lungs decrease pressure in lungs becomes lower than pressure in air outside creating pressure gradient air flows down the pressure gradient and into lungs
• what is the process of expiration?

  The external intercostal muscles relax, and ribs move downward and inward the diaphragm relaxed causing it to curve and move upward again

  This decreases volume of thoracic cavity

  Pressure in the lungs increase it becomes higher than atmospheric pressure, reversing the pressure gradient air flows down the pressure gradient and out of the lungs
• what happens if expiration is forced?

  require energy and internal intercostal muscles

  the external intercostal muscles relax by the internal contract this pulls ribcage further down than it normally go
• what are features of alveolar epithelium?


  Single layer of flat cells called alveolar epithelium minimises diffusion distance

  
  

  Large surface area this increases the efficiency of gas exchange

  O2 and CO2 move by simple diffusion

  
  

  network of capillaries to remove exchanged gases, maintains conc gradient

  
  

  Moist lining, gasses dissolve in before moving across membrane gas diffuses more rapidly
• what are factors that affect rate of diffusion?

  A larger surface area

  High temperature

  Small diffusing molecule

  Reduction in diffusion distance- network of pulmonary capillaries is narrow only one pass through at a time this slows down red blood cells meaning that more gas exchange can occur also pushes them closer which decreases diffusion distance, capillary epithelium is only 1 cell thick

  
  

  A steep concentration gradient - constant blood flow this maintains a steep concentration gradient between alveoli and capillaries.

  
  

  Thickness of exchange surface walls= one cell thick theses make wall of capillaries are specialised squamous epithelial cells (very thin)
• as size increases does the SA:V decrease or increase?

  decreases
• why does this happen?

  This is because volume increases much more rapidly than surface area as size increases.
• do larger organisms have smaller or larger sa:v?


  smaller
• what is the definition of pulmonary ventilation?

  total volume of air that is moved into lungs for one minute
• what is the definition of tidal volume?

  volume of air taken in through each breath when body is at rest usually 0.5dm3, measured through a spirometer
• what is the definition of ventilation rate?

  the number of breaths taken in one minute normally 12-20
• how to work out pulmonary ventilation rate?

  pv = TV x VR
• What is vital capacity?


  volume of the largest breath possible
• what is forced expiration volume?

  maximum volume of air that can be breathed out in 1s
• What is anatomical dead space?


  internal volume of upper airways Nose, Pharynx, Trachea, Bronchi
• what is asthma?


  airways inflamed and irritated caused by allergens
• what are the symptoms of asthma?


  wheeze and tight chest
• why does this occur?

  Smooth muscle lining bronchioles to contract and constrict this narrows airway, mucus released.

  Air flow reduced less air moves in and out, less O enters alveoli and into blood

  Conc gradient reduced and less oxygen moves into blood
• What is emphysema caused by?

  smoking and air pollution
• why does emphysema occur?

  Tar causes inflammation response phagocytes invade lungs and enzyme is released which breaks down elastic tissue in lungs, cannot expand and recoil easily

  Less ventilation conc gradient reduced less O in blood cannot get O to tissues
• what are the symptoms of emphysema?


  shortness of breath and wheezing
• how is pulmonary fibrosis caused?

  inhaling particles
• what is pulmonary fibrosis?

  Scar tissue (thicker and less elastic)
• why does pulmonary fibrosis cause issues?

  Lungs less able to expand can't hold as much air as normal. Tidal volume reduced

  Diffusion slower across thicker scarred membrane Less oxygen enters

  Faster ventilation rate to get same amount of air into lungs
• what are symptoms pulmonary fibrosis?

  shortness of breath, dry cough, chest pain, fatigue
• What is tuberculosis caused by?

  Caused by bacterium, from droplets coughing invades epithelial cells and form lumps in which bacteria remains dormant
• why does pulmonary fibrosis cause issues?

  Inflammation response in white blood cells which causes scarring reducing SA and elasticity

  Reduces ROD and tidal volume is reduced
• what's digestion?


  hydrolysis of large biological molecules into smaller molecules which can be absorbed across cell membranes.
• what enzyme breaks down carbohydrates?

  amylase in mouth

  maltase in ileum