Lungs and ventilation Flashcards
what is the structure of the thorax
the lungs are enclosed in the thorax by the ribcage and the diaphragm the actions of the diaphragm and the ribcage bring about the movement of air in and out the lungs.
what are the intercostal muscles
2 sets of muscles joining the ribs together (internal and external intercostals)
what is the diaphragm
a muscular sheet of tissue that separates the thorax from the abdomen. it is a shallow dome shape with a fibrous middle forming a roof and muscular edges for walls
what does ventilation mean
moving air in and out of the lungs
how does ventilation happen (inhalation)
air moves from a place of high pressure to a place of low pressure. the external intercostal muscles contract puling the ribs up and out the diaphragm also contracts flattening itself out. this increases the volume in the thorax slightly dropping the pressure in the thorax below atmospheric pressure which causes air to enter the lungs
how does ventilation happen (exhalation)
the external intercostal muscles relax as well as the diaphragm returning to its dome shape and the internal intercostal muscles contract puling the ribs down and in. this decreases the volume in the thorax causing the pressure in the thorax to rise slightly above atmospheric pressure forcing the air out of the lungs
what is the structure of the gas exchange system
air is inhaled through our mouth and nose and goes down our trachea. the trachea splits into two bronchi the bronchi then divide into smaller and smaller tubes called bronchioles ending in microscopic air sac called alveoli
where does gas exchange happen
in the alveoli
what keep the trachea and bronchi from squashing when we inhale
they contain rings made of cartilage that support the tubes. the ones in the bronchi are full circles but the ones in the trachea are C shaped so that food going down the oesophagus is not hindered by the ridges
what separates the lungs and the thorax
two thin moist membranes that cover the lungs totally in an airtight seal these are called pleural membranes. the space in between the membranes is called the pleural cavity, the cavity has a thin layer of liquid called pleural liquid. this liquid acts as a lubricant for the lungs and the inside of the thorax so they don’t stick together when we’re breathing
what is a defense system of this organ system
the trachea and larger airways are lined with cells that secrete mucus trapping dirt and bacteria and cells that sweep the mucus out towards the mouth. this prevents things like infection
what happens to the cilia when smoke
the cilia gets destroyed messing up this defense
