🏥 Chapter 7 - Respiration in Humans

• Aerobic Respiration


  • release of energy via the breakdown of glucose in the presence of oxygen. Carbon dioxide and water are released as waste products.
  • releases a LARGE amount of energy
  • energy may also be released as heat, which is circulated around your body by blood to keep you warm

  
• Energy-Consuming processes (FYI)


  • synthesis of new protoplasm for growth & repair
  • synthesis of proteins from amino acids
  • active transport in the absorption of food substances by the small intestine
  • muscular contraction such as heartbeats
  • transmission of nerve impulses
  • cell division
• Anaerobic respiration


  • release of energy via the breakdown of glucose in the absence of oxygen.
  • releases a relatively small amount of energy
• Respiration in muscle cells

  1. During vigorous muscle contractions (such as running), muscle cells respire aerobically at a high rate. You start to pant to remove carbon dioxide and take in oxygen at a higher rate
  2. Heart beats faster so that oxygen is transported to your muscles at a faster rate.
  3. When this activity continues one eventually will reach their maximum aerobic respiration and is unable to release anymore energy fast enough.
  4. Muscles carry out anaerobic respiration to meet energy demand
  5. lactic acid is formed in the process
  6. muscles are said to incur oxygen debt

  
• How can oxygen debt be removed after a race?

  • continuation of fast heart rate, which results in continued and fast transport of lactic acid from muscles to liver to be detoxified, and oxygen from lungs to the liver
  • continuation of deep and fast breathing, which results in continued and fast intake of oxygen by the lungs, which removes lactic acid and the oxygen debt is repaid.
• Gas Exchange in Humans

  • exchange of gases between an organism and the environment
• The Nose

  • air usually enters the body through the 2 external nostrils, which lead to nasal passages
  • nasal passages are lined with a moist mucous membrane
  • dust & foreign particles are trapped by hairs in the nostrils as well as mucus on the mucous membrane
  • as air passes through the nasal passages, it is warmed and moistened
  • harmful chemicals are detected by small sensory cells on the mucous membrane
• Human Gas Exchange system diagram

  m

  A) (supported by C-shaped cartilage)

  
• From the nose to the trachea

  • nostrils --> nasal passage --> pharynx --> larynx --> trachea
• Trachea

  • supported by C-shaped rings of cartilage, which keeps the lumen of the trachea open.
  • epithelium is located right next to the lumen
  • epithelium contains

  1. Gland cells which create mucus to trap dust particles & bacteria

  2. Ciliated cells which have cilia (hair-like structures), that sweep dust -trapped mucus up the trachea

  
• Bronchi & Bronchioles

  • trachea divides into two bronchi (singular: bronchus)
  • bronchus carries air into the lung
  • bronchus branch repeatedly to form numerous bronchioles
  • bronchioles always end in a cluster of alveoli
• Alveoli

  • walls of the alveoli are sites of gaseous exchange
• Lung Adaptations for Efficient Gas Exchange

  • numerous alveoli provide a large surface area
  • alveoli wall are one cell thick to provide a short diffusion distance, ensuring a higher diffusion rate
  • film of moisture covers the inner wall of the alveoli, allowing oxygen to dissolve in it
  • walls of alveoli are richly supplied with blood capillaries to maintain concentration gradient of gases

  
• How does gas exchange occur in alveoli?


  • {Blood entering the lungs --> lower O2 concentration + higher CO2 concentration}
  • Oxygen dissolves into the thin film of moisture on the alveolus wall

  • dissolved oxygen diffuses through the wall of the alveolus and the wall of blood capillaries into the red blood cells
  • oxygen now in the blood combines with haemoglobin to form oxyhaemoglobin
  • Carbon dioxide diffuses from blood into the alveolar air

  
• How is O2 transported around the body?

  • o2 and co2 concentration gradients are maintained by continuous flow of blood in capillaries and continuous breathing, and air in lungs is constantly refreshed
  • (in the pic)

  
• The Thoracic (Chest) Cavity


  • internal and external intercostal can be found between ribs
  • they are antagonistic (when one contracts, the other relaxes)

  
• The thorax is separated from the abdomen by a dome-shaped sheet called the diaphragm. The diaphragm is made of muscle and elastic tissue. When the diaphragm muscles contract, the diaphragm flattens downwards, and when they relax, the diaphragm arches upwards again.
• Inspiration (Inhalation)

  • diaphragm muscle contracts, and the diaphragm flattens.
  • external intercostal muscles contract, internal intercostal muscles relax.
  • ribs move upwards and outwards. sternum also moves up and forward.
  • The volume of thoracic cavity increases.
  • lungs expand and air pressure inside them decreases as the volume increases.
  • Atmospheric pressure is now higher than the pressure within lungs.
  • Air moves into the lungs.

  
• Expiration (Exhalation) 


  • diaphragm muscle relaxes and the diaphragm arches upwards
  • internal intercostal muscles contract, external intercostal muscles relax.
  • ribs move downwards and inwards. sternum also moves down to its original position.
  • volume of thoracic cavity decreases.
  • lungs are compressed and air pressure inside them increases as the volume decreases.
  • Pressure within the lungs is now higher than atmospheric pressure. The air is forced out of the lungs to the exterior environment

  
• What Effects Does Tobacco Smoke Have on Human Health?

  Fill the blank

  A) heartbeat

  B) pressure

  C) clots

  D) coronary heart disease

  E) narrow

  F) miscarriage

  G) nicotine

  H) Carbon Monoxide

  I) tar

  J) permanently

  K) haemoglobin

  L) oxygen

  M) coronary heart disease

  N) cancer

  O) division

  P) emphysema

  Q) paralyses

  
• Chronic Bronchitis

  • The epithelium lining of the air passages (airways), for example, the bronchi, becomes inflamed.
  • Excessive mucus is secreted by the epithelium.
  • The cilia on the epithelium are paralysed. Mucus and dust particles cannot be removed.
  • The air passages become blocked, making breathing difficult.
  • In order to breathe, persistent coughing occurs to clear the air passages This increases the risk of getting lung infections.
• Emphysema

  • The partition walls between the alveoli break down due to persistent and violent coughing .
  • This results in a decreased surface area for gaseous exchange.
  • The lungs lose their elasticity and become inflated with air.
  • Breathing becomes difficult. Wheezing and severe breathlessness result.

  
• Studies have shown that the risk of lung cancer increases when a person smokes tobacco. Figure 7.28 showsthe lungs ofa smoker compared to a pair of healthy lungs. According to the Singapore Health Promotion Board, smoking-related diseases in Singapore alone accounts for about seven premature deaths each day.

  
• Structure for Expiration/Inspiration qn

  1. diaphragm muscles (contract/relax)
  2. diaphragm (flattens/arches upward)
  3. external intercostal muscles (contract/relax)
  4. internal intercostal muscles (relax/contract)
  5. ribs moves (upward and outward/ downwards and inwards)
  6. sternum moves (upward and forward/ down into orginal position)
  7. volume of thoracic cavity (increase/decrease)
  8. pressure in lungs (decrease/ increase)
  9. atmospheric pressure (higher/lower) than lungs
  10. air moves (in/out) of the lungs
• yt video on chapter


  https://www.youtube.com/watch?v=bMwpMpifmDM