THE RESPIRATORY SYSTEM

PASSAGEWAYS & LUNGS

FUNCTIONSFUNCTIONS of the respiratory system:

– #1 = obtaining oxygen & removing carbon dioxide = gas exchange

– filtering incoming air– controlling the temp & water content of

incoming air– producing vocal sounds– plays important roles in the sense of

smell & regulation of blood pH

cleaning dirty air:

– there’s millions of particles of foreign matter in air!

– air must be filtered before it reaches the lungs

– the nasal cavity, trachea, & bronchial tree are all lined with ciliated cells that secrete mucus via goblet cells

– the cilia beat upward towards the pharynx, where foreign matter is swallowed or coughed up

the EVENTS of respiration:

1) breathing / ventilation = moving air into or out of the lungs

2) external respiration = gas exchange between blood & the air in the lungs

3) gas transport in blood between the lungs & body cells

4) internal respiration = gas exchange between blood & body cells• cell respiration = using O2 to break

glucose & form ATP

PARTS of the respiratory system: upper respiratory tract

– nose w/ 2 nostrils– nasal cavity / nasal passages

• divided into R & L by the nasal septum (may be deviated)

– paranasal sinuses = air-filled spaces in the bones of the skull

– pharynx = a passageway for air & food

UPPER respiratory tract

PARTS of the respiratory system: lower respiratory tract

– larynx = contains the vocal cords– Trachea = “windpipe”– bronchial tree – branched air passages that

lead from the trachea to the air sacs, or alveoli

parts of the respiratory system: LOWER respiratory tract

– 2 lungs: the right lung has 3 lobes & the left has 2 lobes

– assisted by the diaphragm– controlled by the medulla oblongata & pons in the brain stem

lower respiratory tract

the PATH air takes:

– air is taken in through the nose or mouth = inspiration

– air flows into the pharynx & passes the epiglottis

– it moves through the larynx (voicebox)– it travels down the trachea which splits

into 2 tubes

the PATH air takes:

– a bronchial tube / bronchus leads into each lung

– It branches into smaller bronchioles– Bronchioles end in alveoli where gas

exchange takes place– this pathway is reversed for expiration

alveoli = the place of gas exchange:

– the bronchi branch like a tree (bronchus bronchioles alveoli)

– alveoli are the sacs of the lungs where O2 & CO2 are exchanged by diffusion between the air and blood

alveoli = the place of gas exchange:

– grape-like clusters of alveoli are surrounded by networks of tiny blood vessels / capillaries

– the walls of capillaries and of alveoli are only 1 cell thick

blood transport of gases:

– external respiration = the exchange of O2 & CO2 between the air in the alveoli and the blood that circulates through its capillaries

– once oxygen diffuses into the bloodstream, it is pumped by the heart to all cells in the body

blood transport of gases:

– cellular respiration = the process by which cells use oxygen to break down glucose (via glycolysis) & release energy to form ATP

blood transport of gases:

– carbon dioxide is a waste product & it diffuses into the blood which carries it back to the lungs, then it is exhaled

– blood going into the alveoli is low in O2 & high in CO2

– blood returning from the alveoli is higher in O2 & low in CO2

lung capacity:

– tidal volume = the amount of air that moves in during a respiratory cycle (1 inhalation + 1 expiration)

– residual volume = air remaining in lungs after a maximal exhale

– vital capacity = the maximum amount of air a person can exhale after taking in the deepest breath possible

– total lung capacity = the vital capacity + the residual volume

THE MECHANICS OF BREATHING

• breathing is accomplished via the action of the diaphragm & the muscles between the ribs & is assisted by air pressure

• inhaling contracts the muscles between the ribs & causes the rib cage to rise

• inhaling also contracts the diaphragm, flattening it, causing it to move lower in the chest cavity

THE MECHANICS OF BREATHING

• both of these muscular contractions increase the space in the chest cavity, which creates a slight vacuum

• air rushes to fill the space because the pressure outside your body is greater than the pressure inside your lungs

THE MECHANICS OF BREATHING

• when you exhale (expiration), the rib muscles & diaphragm relax which lowers the rib cage & diaphragm

• this decreases the volume of the chest cavity & forces air out of the alveoli

THE MECHANICS OF BREATHING

• healthy lungs are elastic: they stretch as you inhale & go back to their original size when you exhale

• they are never completely empty – even after exhaling (residual volume)

CONTROL OF RESPIRATION

• usually respiration is involuntary• the respiratory center is in the brain stem

& includes portions of the pons & medulla oblongata

• it is partially controlled by the medulla oblongata which maintains the homeostasis of blood chemistry

CONTROL OF RESPIRATION

• the medulla oblongata responds to higher levels of CO2 in blood by sending nerve impulses to the rib muscles & the diaphragm, causing these muscles to contract & you inhale

RELEVANT VOCABULARY

• apnea = temporary cessation of breathing• asphyxia = O2 deficiency & excess CO2 in

blood & tissues• bronchitis = inflammation of the bronchial

lining• cystic fibrosis = a genetic disorder which

causes the production of extremely thick, sticky mucus which encourages infection + clogs the pancreas + impairs absorption of nutrients + leads to salty sweat

RELEVANT VOCABULARY

• emphysema = a progressive, degenerative disease that destroys alveolar walls therefore reducing the volume of gas exchange

RELEVANT VOCABULARY

• hyperventilation = prolonged rapid & deep breathing

• pleurisy = inflammation of the pleural membranes

• rhinitis = inflammation of the nasal cavity lining

• sinusitis = inflammation of the sinus cavity lining

• spirometer = an instrument that measures respiratory air volume

• tracheotomy = incision in the trachea for exploration or for removal of a foreign object