Respiratory System

• air enters the body through the nasal cavity
• the trachea splits into two bronchi
• each bronchus splits into smaller branches called bronchioles
• the bronchi and bronchioles are made from cartilage to keep them open when you breathe in preventing them from collapsing
• each bronchiole leads to a bunch of air sacs called alveoli
• gas exchange takes place in the alveoli
• the lungs are surrounded by two pleural membranes which line a pleural cavity that is filled with pleural fluid to reduce friction between lungs and ribs when breathing
• the nasal cavity warms and filters air
• the trachea carries air to the bronchi
• the bronchus brings air into right or left lung
• the bronchioles are branched to carry air into many alveoli within lung
• the lungs contain millions of alveoli to give a large surface area
• the alveolus is the site of gas exchange
• the diaphragm is a muscular sheet that contacts or relaxes to aid breathing
• the ribs protect lungs and heart
• intercostal muscles contract to lift ribs up and out
• pleural membranes line thoracic cavity and cover outside of lungs
• pleural fluid acts with pleural membranes to reduce friction when breating
• increased volume = decreased pressure = air sucked in
• in bell jar lung model:

  • lungs = balloons
  • trachea = glass tube
  • diaphragm = rubber sheet
  • ribs = bell jar

  
• when we inhale:

  • diaphragm contracts and flattens
  • ribs move up and out
  • intercostal muscles contract to move ribs up
  • volume of lungs increases
  • pressure in lungs decreases
  • air forced into lungs as external air pressure is greater than internal
• when we exhale:

  • diaphragm relaxes and domes
  • ribs move down and in
  • intercostal muscles relax to move ribs down
  • volume of lungs decreases
  • pressure in lungs increases
  • air forced out of lungs as internal air pressure is greater than external
• alveoli have thin walls for a short diffusion pathway for gases
• alveoli are surrounded by a network of blood capillaries which maintain the concentration gradient
• the alveoli are moist, the layer of moisture dissolves the gases before they pass through
• there are millions of alveoli for a large surface area
• alveoli are well ventilated, oxygen in constant supply, to maintain the concentration gradient
• the air we breath in has a higher concentration of oxygen than the air we breathe out because the oxygen is transported to the cells and used in cell respiration to produce energy
• respiration in the cells produces CO2 as a waste product which is transported back to the lungs in the blood and breathed out
• carbon dioxide diffuses from the blood into the alveoli via simple diffusion
• oxygen diffuses from the alveoli into the blood via simple diffusion
• respiratory systems in animals are designed to deliver oxygen to as surface so that it can be absorbed and then transported to the individual cells in the body, in the cells oxygen is used in cell respiration. to provide large amounts of energy
• to gain energy plants also need to respire, to do this they use some of the glucose made in photosynthesis and oxygen, plant leaves are designed to help gases diffuse
• adaptations of respiration achieved in plants:

  • large surface area, leaves are flat
  • thin, short distance for gases to travel through the stomata to the leaf cells
  • moist, moisture on the outer surface of cells especially the spongy layer of the leaf
  • permeable, cell membranes are permeable to gases in solution
  • diffusion gradient, maintaining a gradient is achieved by gases being used (high-low)
• adaptations of respiration achieved in animals:

  • large surface area, millions of alveoli
  • thin, walls of alveoli are thin- short diffusion distance for gases to travel through
  • moist, gases are more easily transported in solution- layer of moisture on inner surface of alveolus
  • permeable, cell membranes are permeable to gases in solution
  • good blood supply, each alveolus has its own capillary network so that oxygen can reach blood quickly and CO2 can be passed from blood to alveolus
  • diffusion gradient, blood constantly and this maintains a gradient (high-low)
• we get energy from food through cell respiration
• the nutrients that we get from out digested food are oxidised to give CO2 and water and energy is released
• glucose + oxygen -> CO2 + water + energy
• C6H12O6 + 602 -> 6CO2 + 6H2O + energy
• active transport is the movement of substances from and area of low concentration to an area of high concentration, against concentration gradient