Lungs and throat breathe and exchange oxygen and carbon dioxide between air and blood {respiration, animal}.
People take 15 to 18 breaths per minute {breathing rate}. Volume rate is 0.5 liters per minute. Carotid-artery carotid sinus measures blood carbon dioxide and oxygen and sends signals to control breathing rate. Pons pneumotaxic center inhibits breathing after receiving signals from nerves that sense alveoli stretching. Medulla respiratory center sends excitatory signals along phrenic nerve to diaphragm. Pain increases breathing rate. Toxic or irritating gases inhibit breathing rate, at pharynx and larynx.
Total lung air {vital capacity}| is five liters.
chest {bosom}.
lungs, bronchi, and/or tracheae {bronchial}|.
about lungs {pulmonary}|.
Lung elasticity and chest-wall weight can push air out lungs {exhalation}|.
When diaphragm contracts and rib muscles relax, air cavity expands, pressure lowers, and lungs draw in air {inhalation}|.
Abdomen and rib muscles can force exhalation, especially in coughing {cough}| and sneezing.
Abdomen and rib muscles can force exhalation, especially in coughing and sneezing {sneeze}|.
Fish have sacs {air bladder}| that hold air for buoyancy.
Animals with tracheal respiratory systems have exoskeleton breathing pores {spiracle}|.
Air enters nose openings {external nares} {nostril}|.
After nostrils, air goes to open regions {nasal chamber} for smell and then goes to pharynx.
Above larynx, oral tract and nasal tract {vocal tract, throat}| produce speech.
Over larynx is a tissue flap {epiglottis}|.
Epiglottis has two epithelium folds {vocal cord}|, controlled by muscles that can vibrate air from 60 Hz to 350 Hz.
Birds can have thin muscles {syrinx}| that form vocal organ where trachea become bronchi.
Vocal cords are in upper middle larynx {glottis}|.
Air goes to throat {larynx}|. Larynx is behind adam's apple. In infants and vertebrates, flat tongue and high larynx allow simultaneous drinking and breathing, but adult humans have low larynx and downward curving tongue to make a sound chamber and allow non-nasal sounds. Early Homo sapiens [-400000] had tongue and larynx like modern people. Homo erectus had arching in larynx [-2000000], but Australopithecus had no arching and so only nasal sounds.
Larynx is behind cartilage {adam's apple}| at neck front.
Lung cavity {lung}| is closed chamber, at same pressure as air pressure.
Air goes to a tube {trachea, lung} {windpipe}| to lungs.
Windpipe branches into two tubes {bronchus}| {bronchi}, at first-rib level. Bronchi have smooth muscle and cilia, which send foreign particles back toward larynx. In response to irritation or stress, asthma can cause smooth muscle to contract uncontrollably.
Bronchi branch many times and end in open regions {air sac, lung}.
Air sacs have cavities {alveoli}| {alveolus} that have moist mucus walls surrounded by capillaries, which allow gas diffusion into and out of blood. They have air that is higher in carbon dioxide, lower in oxygen, warmer, and more humid, than outside air. Elastic connective tissue surrounds alveoli to aid contraction.
lung cavity and lung lining {pleura, lung}|.
When lung muscles {diaphragm, lung}| contract and rib muscles relax, air cavity expands, pressure lowers, and lungs draw in air for inhalation.
Outline of Knowledge Database Home Page
Description of Outline of Knowledge Database
Date Modified: 2022.0225