VOCAB WORDS:
External Respiration- exchange of oxygen and carbon dioxide between alveoli and blood
Internal Respiration- exchange of oxygen and carbon dioxide between blood and tissue fluid
Gills- respiratory organ in most aquatic vertebrates and invertebrates that extract oxygen from a watery
environment (In fish, an outward extension of the pharynx); they’re finely divided and highly
vascularized outgrowths of the body surface
Operculum- gill covers on fish that open when the mouth closes, and closes when the mouth opens.
When the opercula (plural) are open, water is drawn into the pharynx through the gill slits
located between the gill arches
Countercurrent Exchange- when fluids or gases flow side by side in opposite directions; fish use this
method to transfer oxygen from the surrounding water into their blood during respiration
Concurrent Exchange- when fluids or gases flow side by side in the same direction
Lungs- internal respiratory organ containing moist surfaces for gas exchange; usually found in terrestrial
vertebrates
Tracheae- tiny air tubes that take oxygen directly to the cells; found in the respiratory systems of
insects. They consist of a single layer of cells supported by spiral thickenings of chitin, which
branch into smaller tracheoles.
Pharynx- common passageway for both food intake and air movement in vertebrates; located between
the mouth and the esophagus. Air passes from the pharynx to the glottis
Glottis- an opening into the larynx / air tract opening
Vocal Chords- Flexible bands of connective tissue that vibrate and produce sound when air is expelled
past them through the glottis from the larynx. They’re found at the edges of the glottis,
embedded in the mucus membrane
Epiglottis- structure that covers the glottis during the process of swallowing in order to prevent food
from going down the trachea and air from going down the esophagus
Larynx- cartilaginous organ located between the pharynx and the trachea; in humans, the larynx
contains the vocal chords and is sometimes referred to as the voice box
Trachea- in tetrapod vertebrates, it’s the air tube/ “windpipe” that runs between the larynx and the
bronchi
Bronchi- two branches that the trachea divides into, entering the left and right lungs
Bronchioles- branches that the bronchi split into. Each bronchiole ends in an elongated space enclosed
by a number of alveoli
Alveloi- grape-like air sacs found in the lungs. Internal gas exchange takes place between the air in the
alveoli and the blood in the capillaries
Inspiration- (aka inhalation) the act of moving air into the lungs
Expiration- (aka exhalation) the act of moving air out of the lungs
Diaphragm- a horizontal muscle that divides the thoracic cavity from the abdominal cavity; controls
inspiration and expiration of the lungs through contractions
Respiratory Center- a group of nerve cells in the medulla oblongata of the brain that rhythmically sends
out nerve impulses; sends signals through the spinal cord to the diaphragm and intercostal
nerves to the intercostal muscles (which expand and shrink the chest cavity) located on the rib
cage, creating inspiration. When it stops sending these signals, expiration occurs
Carotid Bodies- structure located at the branching of the carotid arteries; contains chemoreceptors;
stimulates the respiratory center when hydrogen (H+) levels in the blood decrease during
exercise
Aortic Bodies- sensory receptor located in the aortic arch; contains chemoreceptors; stimulates the
respiratory center when H+ levels in the blood decrease during exercise
Partial Pressure- the amount of gas each gas exerts, in this context O2 and CO2; causes the diffusion of
O2 and CO2 across membranes, down the concentration gradient
Carbonic Anhydrase- enzyme that speeds the breakdown of carbonic acid in red blood cells during
external respiration
Oxyhemoglobin- the result of oxygen and hemoglobin combining in the red blood cells found in the
pulmonary capillaries
Heme- an iron-containing group; each of the four polypeptide chains that make up hemoglobin are
folded around a heme
During internal respiration, carbon dioxide collects in the tissue fluid. Once the CO2 diffuses into the
blood, it enters red blood cells to become either carbaminohemoglobin or bicarbonate ions.
Carbaminohemoglobin- formed during internal respiration and inside of red blood cells; product
of CO2 combining with the protein portion of hemoglobin molecules
Bicarbonate Ion- how most CO2 is transported; product of CO2 combining with water to
become carbonic acid, then dissociates into a hydrogen ion and a bicarbonate ion
Acute Bronchitis- infection of the primary and secondary bronchi
Pneumonia- a viral, bacterial, or fungal infection of the lungs in which bronchi and alveoli fill with a
discharge such as pus and fluid
Pulmonary Tuberculosis- caused by the bacterium tubercle bacillus; this bacterium invades the lung
tissue, causing the cells to build a protective capsule (called a tubercle) around the organisms in
order to isolate them from the rest of the body; if the body’s resistance level is too low, the
bacteria can escape
Pulmonary Fibrosis- a condition where fibrous connective tissue builds up in the lungs, causing the lungs
to not be able to inflate properly
Emphysema- a chronic and incurable lung disorder in which the alveoli are distended/ burst, fusing into
enlarged airspaces; this reduction in walls reduces the surface area necessary for gas exchange
Asthma- disease of the bronchi and bronchioles in which the airways are unusually sensitive to specific
irritants, such as allergens or cold air
Lung Cancer- one of many possible outcomes of smoking; the lining of the airways thicken, then there’s
a loss of cilia which allows dirt and dust to more easily enter and settle in the lungs; next cells
with atypical nuclei appear in the thickened lining, and a tumor consisting of these disordered
cells forms (when the tumor stays in one place, it is considered to be cancer in situ (in one
place)); a final step is when some of these cells break away and penetrate other tissues, a
process called metastasis. The original tumor may grow until a bronchus is blocked, cutting off
the supply of air to that lung; the entire lung then collapses, and secretions in the lung spaces
become infected