Respiration

• The function of the respiratory system is to remove oxygen from the air and into the blood, where it can travel to cells in the body for respiration to take place.

  Cells respire all the time, if cells stop respiring, they die.
• Inhalation/inspiration means breathing in.

  Exhalation/expiration means breathing out.
• Passage of air:

  1.Nose/nostrils

  2.Trachea

  3.Bronchus

  4.Bronchiole

  5.Alveoli
• Air enters through nostrils (nose) which are lined with hairs that trap dust particles. The nose also warms up the air as we breathe in. Air then passes down the trachea (windpipe).
• Inhalation/inspiration:

  As volume of the thorax (chest) increases, the lung and thoracic pressure decreases. Air rushes in the lungs through the trachea and the lungs inflate.

  Intercostal muscles contracts and ribcage moves up and out.

  Diaphragm muscle contracts and diaphragm flattens. Pressure in lungs is less than outside body.
• Exhalation/expiration:

  As the volume of the thorax (chest) decreases, the lung and thoracic pressure increases. Air is squeezed out of the lungs.

  Intercostal muscle relaxes and ribcage moves in and down.

  Diaphragm muscle relaxes and diaphragm becomes dome shaped. Pressure in lungs is greater than outside body.
• Bell jar model lungs: Represents the human thorax (chest) during inspiration and expiration.

  Breathe in - rubber sheet is pulled down, the volume of air-tight space around the balloons increases and the pressure in the thorax decreases below atmospheric pressure. The balloons inflate as air is drawn in.
• Model

  Glass tube = trachea

  Bell jar = ribcage

  Balloons = lungs

  Rubber sheet = diaphragm
• Bell jar:

  SAME AS BODY

  • roughly same shape as ribcage

  DIFFERENT FROM BODY

  • jar is solid so can’t move like a ribcage
  • space around balloons is filled with air, space around lungs in thorax is fluid filled
• Balloons:

  SAME AS BODY

  • inflate and deflate like lungs

  DIFFERENT FROM BODY

  • large space around balloons in bell jar but in thorax the space is not big
  • balloons have no alveoli so less surface area than in lungs
• Rubber sheet:

  SAME AS BODY

  • can be moved and made into dome shape like diaphragm

  DIFFERENT FROM BODY

  • when breathing in (inspiration) rubber sheet is pulled downwards below bell jar but in thorax diaphragm only becomes flat
• Improve lungs model?

  • larger balloons to fill space
  • cotton wool or sponges to act as alveoli
• Alveoli:

  • At end of bronchioles
  • have an outer wall and a moist inner lining which dissolves oxygen
  • next to a capillary
  • oxygen diffuses out of alveolus into blood, CO2 diffuses into alveolus from blood
• Adaptation to function of efficient gas exchange

  • large surface area
  • one cell thick - short diffusion distance, easier gas exchange
  • lining of alveolus- gases dissolve in moisture for easier diffusion - blood moves oxygen away from the exchange surface and CO2 towards it, maintaining diffusion gradient, speeding up diffusion
• composition of inhaled air:

  • 21% oxygen
  • 0.04% carbon dioxide
  • 78% nitrogen
  • water vapour varies
• composition of exhaled air:

  • 16% oxygen
  • 4% carbon dioxide
  • 78% nitrogen
  • saturated water vapour
• Lime water can be used to detect carbon dioxide in inspired and expired air. If the lime water turns milky white, carbon dioxide is present.
• Goblet cell: produces sticky mucus - dust/bacteria get caught in the mucus
• Ciliated cell: A type of cell that has cilia, which moves the mucus and any trapped particles upwards to the throat and out of the lungs - it’s then swallowed.
• Chemicals in smoking paralyse cilia - stop working.

  Mucus builds up from particles in smoke and become thick blocking the airways as it’s harder to move, this increases bacteria in mucus and more infections.

  Heat from smoke kills the mucus and stops airways being moist.
• PASSIVE SMOKING

  breathing in smoke from other peoples cigarretes
• EMPHYSEMA

  Disease where the alveoli are broken and lost, reducing the total surface area for gas exchange, making the victim short of breath.

  Chemicals in smoke and coughing damage alveoli, and they break down - this reduces surface area of alveoli, so less surface for diffusion of oxygen, less gets into blood:

  Person has breathing difficulties

  Short if breath
• Whats in cigarettes?

  • Nicotine - addictive and a stimulant (speeds up nervous system)
  • Tar - carcinogen substance, may lead to lung cancer
  • Carbon monoxide - combines with haemoglobin in red blood cells so less oxygen can be carried
• The process which food is broken down and the energy is released.
• Aerobic respiration:

  Glucose+Oxygen —> carbon dioxide+water+(lots of energy) ATP

  (GOCWE)
• AEROBIC respiration

  • Use glucose and oxygen to produce CO2, water and ATP.
  • Energy is released as heat during respiration.
  • Occurs in mitochondria and is catalysed by energy.
  • Series of enzyme-controlled reactions.
• Anaerobic respiration (human cells):

  Glucose —> Lactic acid+small amount of ATP
• ANAEROBIC respiration

  • Possible to release energy from glucose without oxygen, but not an efficient process and not much energy is released.
  • During hard, vigorous exercise, oxygen cannot diffuse into muscle cells fast enough - muscles repair anaerobically, the partial breakdown of glucose without oxygen being used.
• Comparison

  SIMILARITIES

  • both release energy (make ATP)
  • both breakdown glucose

  DIFFERENCES

  Aerobic respiration:

  • use oxygen
  • CO2 and water are waste products
  • no oxygen debt
  • glucose is completely broken down
  • more efficient - more ATO is made per glucose molecule

  Anaerobic respiration:

  • does not use up oxygen
  • lactic acid is waste product
  • oxygen debt is created
  • glucose is only partially broken down
  • less efficient - less ATP is made per glucose molecule
• CLEANING MECHANISM

  Stops any harmful substance (e.g. tar) to enter bronchioles and alveoli.

  People cough to remove the irritants and this damages the delicate alveoli.

  Bacteria remains in the lungs and can cause chest infections e.g. bronchitis.
• Breathing

  Alveoli - multiple

  Alveolus - 1

  
• Alveoli

  • Oxygen diffuses out - from high concentration to low concentration.
  • CO2 diffuses in - from high concentration to low concentration.
• • A collapsed lung wouldn’t be considered life threatening as there are two lungs in separate cavities and one lung can still work.
• If a hole was on the side of the bell jar when rubber sheet is pulled down…

  • balloons won’t inflate.
  • air is being drawn in through the hole and not the tube.
• Germinating peas

  demonstrate that energy is released as her during respiration

  • Germinating peas washed in disinfectant are placed into Thermos flask.
  • Same mass of germinating peas been boiled and disinfected are placed into second Thermos flask.
• Germinating peas

  
• Germinating peas - results

  • Only living things respire - germinating / living peas respire not dead ones.
  • Peas in flask A respire - produce heat linked to respiration.
  • Temperature rose in flask A but not in flask B.
• Germinating peas

  • Peas respire releasing heat and recorded temperature goes up.
  • Peas are boiled no respiration by peas but recorded temperature increases slightly as peas covered in respiring microbes.
  • Boiled and disinfected peas don’t respire at all do temperature doesn’t go up.