Unit 3

Cards (79)

  • how do insects reduce water loss
    spiracles - open and close to prevent water evaporation
    rigid exoskeleton - covered with waterproof chitin
    small SA:V
  • how do insects have an efficient gas exchange system
    tracheoles - increases surface area + shorter diffusion pathway
    abdominal pumping - reduces pressure + helps to maintain concentration gradient by creating mass movement of air in and out of tracheoles
  • describe the importance of the counter current flow system in fish
    blood and water flow in opposite directions
    maintains a diffusion gradient of oxygen
    gradient is maintained along the whole length of the lamellae
  • describe inspiration (inhalation)
    external intercostal muscles contract
    internal intercostal muscles relax
    ribs are pulled upwards
    volume of the thorax increases
    diaphragm contracts - flattens
    atmospheric pressure is higher than pulmonary pressure so air moves inwards down a pressure gradient
  • describe expiration (exhalation)
    external intercostal muscles relax
    ribs are pulled downwards
    volume of the thorax decreases
    diaphragm relaxes
    atmospheric pressure is lower than pulmonary pressure so air moves outwards down a pressure gradient
    elastic tissue in the alveolar walls recoils to increase pressure and force air out of the lungs
  • state the equation for pulmonary ventilation rate
    PVR = bpm x tidal volume
  • describe the digestion of proteins
    endopeptidases hydrolyse peptide bonds in the middle of a polypeptide
    exopeptidases hydrolyse peptide bonds at the end of a polypeptide
    dipeptidases hydrolyse peptide bonds between two amino acids in a dipeptide
  • what is the function of lipases
    hydrolyse the ester bonds in lipids and split lipids into monoglycerides and fatty acids
  • where are bile salts produced
    liver
  • where are bile salts stored
    gall bladder
  • what is the function of bile salts
    emulsify lipids
    increases surface area
    increases the rate of lipid hydrolysis
  • what are micelles made from and how are they absorbed
    monoglycerides and two fatty acids ( phospholipids ) and bile salts
    simple diffusion through the phospholipid bilayer as they are lipid soluble
  • arteries:
    carry blood away from the heart
    thick muscle layer - contracts and relaxes to control blood pressure
    thick elastic layer - stretches during systole and springs back during diastole (this is called elastic recoil ) + helps to maintain high pressure and smooths out pressure surges
    smooth folded endothelium - reduces friction
    narrow lumen - maintains high pressure
    no valves as blood is under constant high pressure so it cant floe backwards
  • state the correlation between size and surface area to volume ratio
    As size increases surface area to volume ratio decreases
  • Why are smaller units such as micrometers used when calculating values such as oxygen uptake
    Small uptake
  • How does oxygen in the air reach capillaries surrounding alveoli
    Oxygen moves down trachea then to bronchi to bronchioles
    Down a pressure gradient
    down a diffusion gradient
    across alveoli epithelium
    Diffuses across capillary endothelium
  • Explain the digestion and absorption of chylomicrons
    Move out of epithelial cells by exocytosis
    enter lymphatic capillaries called lacteals at the centre of each villus
    pass via lymphatic vessels into blood stream
    triglycerides are hydrolysed by lipases in the endothelial cells of capillaries
    diffuse into cells
  • Describe translocation
    At the source cell sucrose is actively transported into the phloem
    by companion cells
    the water potential in the phloem decreases
    water moves in by osmosis
    produces high hydrostatic pressure
    mass flow of sucrose towards sink cells
    at the sink sugars are removed / used in respiration
  • what is the equation for pulmonary ventilation rate
    tidal volume x breathing rate
  • define tidal volume
    the volume of air breathed in with each normal breath
  • Which blood vessel supplies the heart with deoxygenated blood?
    Vena Cava
  • What is Fick's Law?
    the rate of diffusion is proportional to surface area x difference in concentration divided by length of diffusion pathway
  • What are the adaptations of the alveolar epithelium
    alveoli are one cell thick - short diffusion pathway
    surrounded by network of capillaries - maintained concentration gradient
    many alveoli - large surface area
    folded - large surface area
    moist - gases can dissolve for diffusion
  • Where is there High partial pressure of CO2? and what is the effect
    In respiring tissues
    the curve will shift to the right
    Hb has a lower affinity
    unloading more oxygen
  • Where is there low partial pressure of CO2?
    In the alveoli.
    This causes the curve to shift left
    which increases the affinity of oxygen
    loading more oxygen.
  • where are lipases produced and what do they do
    Produced in the pancreas
    hydrolyse the ester bonds in the triglycerides to form monoglycerides and fatty acids.
  • Where does the digestion of proteins occur?
    stomach
    then duodenum
    fully digested in ileum
  • Where is amylase present?
    Salivary glands
    pancreas.
  • what are the adaptations of the phloem
    sieve plates - has sieve pores which allow for the continuous flow of organic compounds
    cellulose cell wall - provides strength to withstand high turgor and hydrostatic pressure that moves assimilates
    no organelles - maximise space for translocation of assimilates
    thin cytoplasm - reduced friction to facilitate movement of assimilates
  • Where is there High partial pressure of CO2
    respiring tissues
    curve shifts to the right
    haemoglobin has lower affinity for oxygen
    more oxygen unloaded
  • Where is there low partial pressure of CO2?
    alveoli
    curve shifts to the left
    haemoglobin has a higher affinity for oxygen
    more oxygen loaded
  • Why do insects leave their spiracles closed a majority of the time
    prevent water loss
  • describe the absorption of lipids
    micelles diffuse into the epithelial cells lining the villi
    monoglycerides and fatty acids are released
    monoglycerides and fatty acids are transported to the smooth endoplasmic reticulum where they recombine to form triglycerides
    triglycerides are transported to the Golgi body where they associate with cholesterol and lipoproteins to form chylomicrons
    chylomicrons leave epithelial cells by exocytosis and enter lacteals
  • adaptations of phloem
    sieve plates with sieve pores - allow for continuous movement of organic compounds
    cellulose cell wall - provides strength to withstand hydrostatic pressure that moves the assimilates
    no organelles - maximise space for translocation
    thin cytoplasm - less friction to facilitate movement of assimilates
  • adaptations of xylem
    lignin in walls - gives strength to prevent collapse due to hydrostatic pressure
    lignin kills cells because it is waterproof = no organelles in cells = continuous column = unimpeded flow of water
    pits in wall - lateral movement of water + continuous flow if air bubbles form
    no end plates forming a long continuous tube - assists cohesion of water molecules as adhesive forces of hydrogen bonding is not impeded
  • describe alveoli
    minute air sacs at the end of bronchioles
    collagen and elastic fibres between alveoli
    lined with epithelium
    elastic fibres - allow them to stretch as they fill with air when breathing in and spring back during exhalation to expel carbon dioxide rich air
  • what cells produce mucus
    goblet
  • Describe the cohesion-tension theory of water transport in the xylem 
    water transpires from leaves - evaporates from mesophyll cells into air spaces and diffuses through open stomata
    reduces water potential in mesophyll cells
    water is drawn out of xylem down a water potential gradient
    created tension in xylem
    cohesive forces between water molecules due to hydrogen bonding
    water is pulled up as a continuous unbroken column
    water adheres to xylem walls
    water enters root by osmosis
  • why is diffusion of gases between the alveoli and the blood rapid
    red blood cells slowed as they pass through capillaries so there is more time for diffusion
    red blood cells are flattened as they pass through capillary walls so short diffusion pathways
    alveoli epithelium and capillary endothelium are one cell thick so short diffusion pathway
    many capillaries and alveoli so large surface area
    breathing allows for steep concentration gradient
    blood flow through capillaries maintains concentration gradient
  • why is oxygen uptake a measure of metabolic rate
    oxygen is used in respiration which provides ATP