MLT GlobeAnatomy: Respiratory system
31 Anatomy MCQs on Respiratory system with answers and explanations.
How many external nares (nostrils) open onto the face?
The nasal septum divides the nose into two cavities, each opening by one anterior naris, giving two nostrils (one pair).
Gas exchange in alveoli is favoured by a thin lining of which epithelium?
Type I pneumocytes are flat simple squamous cells giving a very short diffusion distance; type II cells secrete surfactant.
During exercise, sympathetic stimulation affects the airways by causing:
Sympathetic activity relaxes bronchial smooth muscle through beta-2 receptors, widening airways. Parasympathetic (vagal) activity causes bronchoconstriction.
Which organ containing the vocal folds is commonly called the 'voice box'?
The larynx houses the vocal folds that vibrate to produce sound. The pharynx is a shared air–food passage above it; the trachea is the windpipe.
Which statement about the lungs is correct?
The left lung has two lobes (upper and lower) because the heart takes space; the right has three. The lungs lie above the diaphragm on either side of the mediastinum.
The common name 'windpipe' refers to which airway?
The trachea runs from the larynx (C6) to its bifurcation (T4/5). The larynx is the voice box; the pharynx is the throat.
Which structure lies immediately above (superior to) the trachea?
The trachea begins at the lower border of the cricoid cartilage of the larynx. The bronchi are below; the oesophagus is behind.
How many lobes does the right lung have?
The right lung has upper, middle and lower lobes separated by horizontal and oblique fissures; the left lung has two.
Bronchoscopy shows the ridge where the trachea splits into the two main bronchi. This landmark is the:
The carina is a keel-shaped ridge at the lowest end of the trachea, at the bifurcation. The hilum is where structures enter the lung.
Which feature is characteristic of the right lung?
The right lung has three lobes and is shorter and wider, as the liver raises the right dome of the diaphragm. The cardiac notch and lingula belong to the left lung.
What is the main function of the curled nasal conchae (turbinates)?
Conchae increase the surface area of the nasal mucosa, promoting warming, humidifying and filtering of air. Lightening the skull is a role of paranasal sinuses.
Approximately how many C-shaped hyaline cartilage rings support the trachea?
About 16–20 incomplete hyaline cartilage rings keep the trachea open; the posterior gap is bridged by trachealis muscle next to the oesophagus.
The outer layer of the tracheal wall that encloses the cartilage rings is made of:
The adventitia of the trachea is fibroelastic connective tissue enclosing the cartilages, allowing flexibility while maintaining shape.
The trachea divides into the main bronchi at about which vertebral level?
The tracheal bifurcation (carina) lies at about T4–T5, level with the sternal angle; the trachea begins at C6.
Which laryngeal cartilage forms a complete ring, shaped like a signet ring with a broad posterior plate?
The cricoid is the only complete cartilage ring of the airway, broader behind than in front. The thyroid cartilage is open posteriorly.
The apex of each lung rises into the neck about 2.5 cm above which part of the clavicle?
The lung apex projects about 2.5 cm above the medial third of the clavicle, so it can be injured by needles or wounds at the root of the neck.
Most of the respiratory tract mucosa below the vocal folds, including the larynx, is lined by:
Respiratory epithelium (pseudostratified ciliated columnar with goblet cells) lines most of the larynx and trachea; the vocal folds themselves have stratified squamous epithelium.
Why does the lung stay expanded against the chest wall?
Negative intrapleural pressure holds the lungs against the chest wall; only a few millilitres of pleural fluid are normally present. Air entry (pneumothorax) collapses the lung.
During quiet breathing at rest, which muscles produce inspiration?
Quiet inspiration uses the diaphragm and external intercostals; expiration is passive recoil. Scalenes and sternocleidomastoid assist only in forced inspiration.
The epiglottis stays flexible because it is made of which type of cartilage?
Elastic cartilage, rich in elastic fibres, is found in the epiglottis and external ear. Hyaline forms growth plates; fibrocartilage forms discs and menisci.