chap 6 respiration in humans

• what is aerobic respiration ?

  it is the release of energy by the breakdown of glucose in the presence of oxygen, where carbon dioxide and water are released as waste products. it releases a large amount of energy
• what is overall equation for aerobic respiration of glucose ?

  C6H12O6 + 6O2 -> 6CO2 + 6H2O

  glucose + oxygen -> carbon dioxide + water
• what are some examples of energy- consuming processes in organisms ?

  • synthesis of new protoplasm for growth and repair
  • synthesis of proteins from amino acids
  • active transport in the absorption of food substances by the small intestine
  • muscular contractions such as heartbeats and respiratory movements
  • transmission of nerve impulses
  • cell division
• what is anaerobic respiration ?

  It is the release of energy by the breakdown of glucose in the absence of oxygen, releasing a relatively small amount of energy
• what is the word equation for anaerobic respiration in human muscles ?

  glucose -> lactic acid
• why is there oxygen debt ?

  there is insufficient oxygen to meet the demands of the vigorous muscular contractions
• what is oxygen debt ?

  it is the amount of oxygen required to remove lactic acid
• how can oxygen debt be removed after exercise ?

  • continuation of fast hear rate
  • fast transport of lactic acid from the muscles to the liver to break down and oxygen from the lungs to the liver
  • continuation of deeper and faster breathing
  • fast intake of oxygen by the lungs
  • sufficient oxygen to remove the lactic acid
• how to detect aerobic respiration ?

  if organism consumes oxygen and gives off carbon dioxide and heat as energy is released in the form of heat
• how to detect anaerobic respiration ?

  organism like yeast give off carbon dioxide in the absence of oxygen
• what is gas exchange ?

  is it the exchange of gases between an organism and the environemnt
• what are some features of the nose and its benefit ?

  • has nose hair
  • dust and foreign particles, including bacteria in the air, are trapped by the hairs in the nostrils as well as by the mucus on the mucous membrane
  • nasal passage is lined with moist mucous membrane
  • air is warmed and moistened
  • harmful chemicals may be detected by small sensory cells in the mucous membrane
• what features of the trachea prevents pathogens from entering the body ?

  • gland cells
  • secrete mucus to trap dust particles and bacteria
  • ciliated cells
  • have hair- like structures called cilia on their surface which sweep the dust- trapped mucus up the trachea
• how are the lungs adapted for efficient gas exchange ?

  • numerous alveoli in the lungs
  • provide larger surface area for gas exchange
  • wall of alveolus is only one cell thick
  • provides a short diffusion distance for gases, ensuring a higher rate of diffusion
  • thin film of moisture covers the inner wall of alveolus
  • allows oxygen to dissolve in it
  • walls of alveoli are richly supplied with blood capillaries
  • maintains the steep concentration gradient of gases
• how does gas exchange occur in the alveoli ?

  • blood entering the lungs has a lower concen. of oxygen and a higher concen. of carbon dioxide than the atmospheric air entering the alveoli in the lungs
  • this sets up a concentration gradient for oxygen and carbon dioxide between the blood and alveolar air
  • oxygen dissolves into the thin film of moisture on the wall of the alveolus
  • the dissolved oxygen diffuses through the wall of alveolus and wall of blood capillary into the rbc
  • oxygen combines with haemoglobin to form oxyhaemoglobin
  • carbon dioxide diffuses from the blood into alveolar air
• how is the concentration gradient of oxygen and carbon dioxide in the alveolar air and blood maintained ?

  • continuous flow of blood through the blood capillaries
  • continuous breathing, causing air in the lungs to be constantly refreshed
• describe the process of inhalation

  • the diaphragm muscle contracts and flattens
  • the external intercostal muscles contract while your internal intercostal muscles relax
  • ribs move upwards and outwards while sternum moves up and forward
  • the volume of chest cavity increases, lungs expand and the air pressure inside them decreases as the volume increases
  • atmospheric pressure is now higher than the pressure within the lungs
  • air is forced into the lungs
• describe the process of exhalation

  • the diaphragm muscle relaxes and arches upwards
  • the internal intercostal muscles contract while your external intercostal muscles relax
  • ribs move downwards and inwards while sternum moves down to its original position
  • the volume of chest cavity decreases, lungs are compressed and the air pressure inside them increases as the volume decreases
  • pressure within the lungs is now higher than the atmospheric pressure
  • air forced out of the lungs to the exterior environment
• components concentration in inspired air and expired air respectively

  • oxygen: higher | lower
  • carbon dioxide: lower | higher
  • nitrogen: about the same
  • water vapour: variable | saturated
  • dust particles: variable | little to none
  • temperature: variable | body temperature (37 degrees)
• why does the air we expire have saturated levels of water vapour ?

  some water evaporates from the surface of the alveoli
• what does tobacco smoke consist of ?

  nicotine, carbon monoxide, tar
• what are the effects of nicotine ?

  • increased heartbeat rate and blood pressure
  • increase risk of blood clots in arteries, leading to higher risk of coronary heart disease
  • increase risk of arteries to narrow
• how can the narrowing of arteries be harmful to pregnant mothers ?

  there would be a decrease amount of food substances reaching the fetus, affecting fetal development and may cause miscarriage
• what are the effects of carbon monoxide ?

  • reduce ability of blood to transport oxygen as carbon monoxide bind permanently to haemoglobin, causing less haemoglobin to be available to transport oxygen
  • in a pregnant mother, less oxygen reaches the fetus through the placenta, affecting fetal development
  • increases risk of coronary heart disease
• what are the effects of tar ?

  • increases the risk of cancer in the lungs as tar can cause uncontrolled cell division
  • increases the risks of chronic bronchitis and emphysema
  • tar paralyses the cilia lining the air passages, causing dust particles trapped in the mucus lining to be unable to be removed
• what diseases are caused by tobacco smoke ?

  • chronic bronchitis
  • emphysema
  • lung cancer
• how can tobacco smoke cause chronic bronchitis ?

  • the epithelium lining of the air passages (eg. bronchi) becomes inflamed
  • excessive mucus is secreted by the epithelium
  • cilia on the epithelium are paralysed, causing mucus and dust to not be able to be removed
  • air passages become blocked, making breathing difficult
  • in order to breathe, persistent coughing occurs to clear the air passages, increasing risk of lung infections
• how can tobacco smoke cause emphysema ?

  due to persistent and violent coughing caused by bronchitis

  • partition walls between the alveoli break down due to persistent and violent coughing
  • this results in decreased surface area for gaseous exchange
  • lungs lose elasticity and become inflated with air
  • breathing becomes difficult, wheezing and severe breathlessness result