science chapter 2 : respiration

• what is breathing?


  a process of inhaling and exhaling air by the lungs
• what are the function of human respiratory system?


  supplies oxygen and removes carbon dioxide from the body cells
• what are the flow of breathing?


  nostrils > nasal cavity > pharynx > larynx > trachea > bronchus > bronchiole > alveolus
• what happen when we inhale? -


  -intercostal muscle: contract and pull

  -rib cage: moves upwards and outwards

  -diaphragm muscle: contract and pull

  -diaphragm: descent and flatten

  movement of rib cage makes,

  -thoracic cavity: bigger

  -air pressure in thoracic cavity: decrease

  -air pressure: high outside

  LASTLY:air forced to enter the lungs
• what happen when we exhale?


  -intercostal muscle: relax

  -rib cage: moves downwards and inwards

  -diaphragm muscle: relax and curve upwards

  movement of rib cage and diaphragm makes,

  -thoracic cavity: smaller

  -air pressure in thoracic cavity: increase

  -air pressure: high inside

  LASTLY:air forced exhaled out
• explain the movement and exchange of gases in the human body.


  1. air inhaled into the alveolus ( higher concentration of oxygen ) than in the blood. therefore,oxygen diffuse through wall of alveolus into walls of capillaries then into the blood

  
  

  2. red blood cells ( dark red coloured compound ) which are called haemoglobin are then combined with oxygen to become oxyhaemoglobin (bright red unstable compound)

  
  

  3. blood with oxyhaemoglobin are transported from lungs to the heart and pumped to other parts of the body.

  
  

  4. when blood reaches area around body cells ( low concentration of oxygen ), oxyhaemoglobin will decompose to release oxygen molecule and turn back into haemoglobin.

  
  

  5. in body cells, diffused oxygen oxidises glucose molecule into carbon dioxide, water and energy through cellular respiration.

  
  

  6. carbon dioxide released by cells diffuse into blood capillaries and transported to the alveolus to be removed ( exhalation )

  ​
• chemical equation of cellular respiration


  glucose + oxygen --> carbon dioxide + water + energy
• what are the adaptations of the alveolar structure?


  1. moist walls of alveolus

  -(respiratory gases diffuse into the blood capillaries)

  
  

  2. large surface area of alveolus

  -(for gaseous exchange)

  
  

  3. thin walls of alveolus and blood capillaries

  -(one cell thick & increase rate of diffusion of gases)

  
  

  4. surrounded by a large network of blood capillaries (covering the alveolus)

  -(increase rate of gaseous exchange between alveolus & blood capillaries)

  
  

  ​
• what are harmful substances for respiration?


  1. cigarette tar

  -kill cells in air passage

  -increase mucus, phlegm in lungs

  -lung cancer

  
  

  2. carbon dioxide

  -colourless, odourless

  -cig smoke & exhaust gases of motor vehicle

  
  

  3.sulphur dioxide

  -combustion of coal

  -colourless and pungent smell

  -cough, bronchitis,lung cancer, difficulty of breathing

  
  

  4.nitrogen dioxide

  -combustion of fuel

  -brown colour and pungent smell

  -irritate air passage,cough, difficulty in breathing,asthma

  
  

  5.haze,dust,pollen

  -irritate respiratory system, asthma
• why is carbon monoxide dangerous?


  It will combine with haemoglobin in blood and produce carboxyhemoglobin (stable compound) and cause shortage of oxygen in blood.
• what are the types of respiratory diseases?


  1. asthma

  2. bronchitis

  3. emphysema

  4. lung cancer
• what will cause asthma?


  dust,pollen,haze,smoke from cigarette,motor vehicle exhaust, open burning and forest fires
• what are the symptoms of asthma?


  shortness of breath, wheezing, coughing
• what will cause bronchitis?

  ​

  tar and irritants in cigarette smoke
• what are the symptoms of bronchitis?


  shortness of breath,coughing and insomnia
• what are the cause of emphysema?


  alveoli that are damaged by harmful substances in the air
• what are the symptoms of emphysema?


  shortness of breath, pain when breathing,tired doing light task
• can emphysema be cured?


  no,but the symptoms can be controlled
• what are the cause of lung cancer?


  carcinogens which are cancer causing chemical substances (inhaled during breathing)

  -in cig smoke (tar)
• what are the symptoms of lung cancer?


  coughing, blood in phlegm,pain when breathing
• what is the respiratory system for frogs? and state the characteristics


  MOIST OUTER SKIN:

  -thin

  -permeable to gas

  -moist ( covered by a layer of mucus and makes respiratory gases dissolve and diffuse more easily )

  UNDER THE LAYERS OF SKIN:

  -dense network of blood capillaries

  > increase the diffusion rate of gases between skin and blood capillaries
• what is the respiratory system for fish? and state the characteristics


  GILLS:

  -made up of two rows of fine filaments (thin and flat projections) known as lamellae

  -number of filaments and lamellae produces a large surface area to facilitate gaseous exchange

  -as fish live in water, gill surrounded by water (moist) and cause respiratory gases to dissolve and diffuse easily
• what is the respiratory system for insects? and state the characteristics


  TRACHEA: >air tubes

  -air enters and leave trachea through breathing pores (spiracles)

  -opening and closing of spiracles are controlled by valves to allow air to leave and enter the body

  -trachea are divided into fine branches (tracheoles)

  TRACHEOLE:

  -thin and moist wall (increase efficiency of gaseous exchange)

  -large number of tracheoles provide large surface area to facilitate gaseous exchange through diffusion into the cells

  (thin tracheoles,thin,moist walls)
• what is respiratory system of insects such as grasshopper?


  TRACHEA SYSTEM:

  >have air sacs - filled with air to increase rate of exchange of respiratory gas between tissues and surrounding during energetic activities.
• during the day,plants take in and give out?


  take in → CO2 and oxygen

  give out → oxygen and CO2
• during the night,plants take in and give out?


  take in → oxygen

  give out → CO2
• what part of the plant carry the process of gaseous exchange with their surroundings?

  through leaves,stems,roots
• what does the leaves,stem,roots of plant provide?


  large surface area for gaseous exchange
• where did the diffusion of CO2 occur through?


  through stoma according to the difference in concentration of CO2 in cells
• what is stoma made from?


  stomatal pore
• what does stoma bounded by?


  a pair of guard cells for photosynthesis
• during the day, the stomata of plants..

  open for photosynthesis
• when does a stomata of a plant closes?


  when it is dark and when plants loses a lot of water
• what is osmosis?


  the process of movement of water molecules from a region of high concentration of water molecules (low concentration of solutes) to a region of low concentration of water molecules (high concentration of solutes) through semipermeable membrane
• semipermeable membrane is permeable to water but not to..


  solutes like sucrose molecules
• how does osmosis occur in guard cells?

  when the concentration of glucose in guard cells increase causing the water around the cells to diffuse into the guard cells. (light→photosynthesis=glucose)
• water diffuse into guard cells and then become?

  turgid and curved, stoma is opened
• water diffuse out of guard cells and then become..

  flaccid and straight,closing of stoma
• explain pathway of gaseous exchange in leaves during photosynthesis.

  •when CO2 is used in photosynthesis,the concentration of CO2 is lower in the cells and higher in air space between cells

  •the difference in concentration allow CO2 in the moist outer skin of cells to dissolve from the air space between the cells into the cell

  •when the concentration of CO2 is lower in the air space between cells, concentration of CO2 in the air outside stoma is higher and causes diffusion of CO2 from atmosphere into air space between cells through stoma.