The ridge of cartilage where the trachea divides into the two main bronchi is called the carina.
Missing Word
carina
The carina is the internal ridge at the tracheal bifurcation. Its lining is very sensitive, and irritation there triggers a strong cough reflex.
Category: Upper and Lower Airway
Question 2
The cartilaginous organ that houses the vocal folds and connects the pharynx to the trachea is the larynx.
Missing Word
larynx
The larynx, or voice box, is built of cartilages including the thyroid, cricoid and epiglottis. It sits between the pharynx and the trachea and produces sound as air vibrates the vocal folds.
Category: Upper and Lower Airway
Question 3
Tiny sacs at the ends of the respiratory tree, where oxygen and carbon dioxide are exchanged with the blood, are called alveoli.
Missing Word
alveoli
Alveoli are the functional units of gas exchange. Their thin walls lie against pulmonary capillaries, giving a large surface area with a short diffusion distance.
Category: Lungs and Pleura
Question 4
The lipoprotein film that lowers surface tension in the air sacs and keeps them from collapsing is called surfactant.
Missing Word
surfactant
Surfactant is a mixture of phospholipids and proteins that reduces the surface tension of the watery film lining the alveoli. Without it, the alveoli would tend to collapse at the end of each exhalation.
Category: Lungs and Pleura
Question 5
Each lung is enclosed in a double-layered serous membrane called the pleura.
Missing Word
pleura
The pleura has a visceral layer on the lung and a parietal layer on the thoracic wall. The thin fluid-filled space between them reduces friction and helps the lungs follow the chest wall.
Category: Lungs and Pleura
Question 6
The ease with which the lungs and chest wall stretch during breathing is called compliance.
Missing Word
compliance
Compliance describes how readily the lungs expand for a given change in pressure. Scar tissue, as in fibrosis, lowers it, and surfactant helps keep it high.
Category: Mechanics of Breathing
Question 7
The phrenic nerve, arising from cervical spinal nerves, stimulates the main muscle of inspiration.
Missing Word
phrenic
The phrenic nerve carries motor signals to the diaphragm. It originates from cervical spinal nerves, so a high cervical spinal cord injury can stop breathing.
Category: Mechanics of Breathing
Question 8
When O2 binds the iron-containing protein of red blood cells, the compound formed is called oxyhemoglobin.
Missing Word
oxyhemoglobin
Oxyhemoglobin is hemoglobin with oxygen bound to its heme iron. It forms in the lungs where oxygen partial pressure is high and gives up its oxygen in the tissues.
Category: Gas Transport
Question 9
Along with the medulla oblongata, the brainstem region called the pons helps regulate the rhythm of breathing.
Missing Word
pons
The pons contains respiratory groups that adjust the rate and depth of breathing set by the medulla oblongata, smoothing the transition between inspiration and expiration.
Category: Control and Development
Question 10
An increase in the depth and rate of breathing that matches the oxygen demand of exercise, with little change in blood gas levels, is called hyperpnea.
Missing Word
hyperpnea
Hyperpnea is increased ventilation that meets a higher metabolic demand, so blood oxygen and carbon dioxide stay near normal. It differs from hyperventilation, which exceeds the body's needs and lowers blood carbon dioxide.
Category: Control and Development
Question 11
The gradual adjustment of the body to long-term exposure to high altitude is called acclimatization.
Missing Word
acclimatization
Acclimatization at altitude includes increased erythropoietin release and red blood cell production, so the blood carries more total oxygen. Over time it allows exertion with fewer symptoms of altitude sickness.
Category: Control and Development
Question 12
Air leaking into the space between the lung and the chest wall, causing the lung to collapse, is called a pneumothorax.
Missing Word
pneumothorax
A pneumothorax is air in the pleural cavity. It removes the negative pressure that normally holds the lung against the chest wall, so the elastic lung recoils and collapses.
Category: Lungs and Pleura
Question 13
Mucus with trapped particles is swept toward the pharynx by the beating of hairlike projections on the airway epithelium called cilia.
Missing Word
cilia
Cilia are motile hairlike projections on the cells lining the airways. Their coordinated beating moves the mucus blanket toward the pharynx, upward from the lower airways and backward from the nasal cavity, so it can be swallowed or coughed out.
Category: Upper and Lower Airway
Question 14
Small airways that branch from tertiary bronchi and lack cartilage in their walls are called bronchioles.
Missing Word
bronchioles
Bronchioles are the narrow airways beyond the bronchi. Their walls have smooth muscle but no cartilage, so contraction of that muscle can sharply narrow them, as happens in asthma.
Category: Upper and Lower Airway
Question 15
The narrow upper tip of each lung, which rises slightly above the clavicle, is called the apex.
Missing Word
apex
The apex is the superior point of the lung. The broad inferior surface that rests on the diaphragm is the base.
Category: Lungs and Pleura