respiratory system

• the bronchi are tubes that branch off from the trachea into the lungs
• alveoli are tiny air sacs where gas exchange occurs between blood and air
• bronchial tree is made up of smaller branches called bronchioles which end at alveoli
• inspiration is when we breathe in, diaphragm contracts downwards to increase volume of chest cavity so pressure decreases causing air to rush in
• expiration is when we breathe out, diaphragm relaxes back up increasing pressure inside chest cavity so air rushes out
• the process of production of energy inside the cells is known as respiration
• food is broken down into simpler substances during respiration
• energy is produced in the form of ATP(adenosine triphosphate)
• breathing is the mechanical exchange of gases
• cellular respiration is the biochemical process that involves the breakdown of glucose to release energy
• the primary function of the respiratory system is to supply oxygen-rich blood and to eliminate the waste product of respiration which is carbon dioxide
• air enters the nasal cavity through nostrils
• the nasal and mouth cavity are separated by the palate
• the functions of the nasal cavity are:

  1. filter outs foreign particles
  2. to cool or warm the air inhaled
  3. to moisten the inhaled air
• the pharynx is the common passage for the mouth and the nasal cavity
• the opening of the trachea is known as the glottis
• the pharynx is lined with stratified epithelial lining
• the glottis is guarded by a flap like structure called the epiglottis
• functions of the epiglottis are:

  • prevents the entry of food into the trachea
  • makes sure food enters the food pipe
• functions of the larynx:

  1. it helps in producing sound hence known as the voice box
  2. larger in men and is seen projecting on the front side of the neck
• the trachea is supported by the cartilage rings.
• trachea has a mucous lining
• the cartilaginous rings keeps the passage open all the time
• the mucous lining in the trachea traps dust particles and pushes them back using cilia
• bronchi also have cartilage rings
• alveoli are very thin and are surrounded by blood capilaries
• the left lung is divided into two lobes: the superior and the inferior
• the right lung is divided into three lobes: the superior, middle, and inferior
• alveoli are the functional unit of the lungs
• the lungs are covered by an external membrane called pleura
• the diaphragm is a sheet like muscle at the bottom of the chest cavity
• during inhalation the ribs move upward and outward and the diaphragm moves downwards
• during exhalation the ribs move back to their original position and the diaphragm returns to its normal position
• bronchioles carry air to alveoli where gas exchange takes place
• alveoli have thin walls that allow gases to diffuse easily between them and the capillaries
• the blood that is carried by the capillaries surrounding the alveoli combines with oxygen, hence the blood is oxygenated
• oxygenated blood leaves the lungs via pulmonary veins
• the carbon dioxide that is produced by the cells combines with the blood and is carried to the lungs by the blood capillaries and then it is expelled
• in ameoba and hydra, exchange of gases takes place through the body surface by means of diffusion
• the trachea is insects opens outside the body through small pores called spiracles