Respiratory System

Question 1

Describe the position of the lungs within the thorax.

Answer 1

Located either side of mediastinum in thoracic cavity.
Extend from base of neck to diaphragm
Surrounded by rib cage for protection
Each lung fits into a pleural cavity.
Right lung larger and has 3 lobes - superior, middle and inferior
Left lung smaller and has 2 lobes - superior and inferior.

Question 1

What organs make up the upper and lower respiratory tract?

Answer 1

Upper is pharynx, nasal cavity, sphenoidal and frontal sinus.
Lower is larynx, trachea, bronchi and lungs.

Question 2

Explain the blood air barrier

Answer 2

Specialised structure that facilitates the exchange of gases between the alveoli of the lungs and the bloodstream.
Contains pneumocytes, endothelial cells of capillaries and basement membrane.
Structure is designed to increase SA and minimise distance for diffusion to ensure efficient gas exchange.

Question 3

Describe the structure of a bronchiole

Answer 3

Simple columnar epithelium.
No cartilage or glands
Prominent smooth muscle - contraction and relaxation of smooth muscle regulate the diameter of bronchioles, controlling airflow into the alveoli
Contain non-ciliated Clara cells, which secrete surfactant and play a role in protecting the airways from pollutants and toxins.
Collagen fibres provide structural support and help maintain the shape and integrity of the bronchioles.
Elastic fibres provide elasticity to the bronchiole walls, allowing them to stretch and recoil during breathing movements.
Innervated by autonomic nerves, including the vagus nerve (parasympathetic) and sympathetic nerves, which regulate smooth muscle tone and bronchomotor activity

Question 4

Describe the structure of a tertiary bronchus.

Answer 4

Pseudo-stratified columnar ciliated epithelium
Hyaline cartilage - provide structural support to the airway walls and prevent collapse during respiration
Spirally arranged smooth muscle - Contraction and relaxation of smooth muscle in response to neural and hormonal signals adjust the bronchial diameter, enabling bronchoconstriction or bronchodilation
Goblet cells secrete mucus

Question 5

Describe the pharynx.

Answer 5

Pharynx connects nasal and oral cavities to the larynx and trachea
Subdivided into 3 sections - superior nasopharynx, oral pharynx and laryngeal pharynx
Passageway for air and food.

Question 6

Describe the larynx

Answer 6

The larynx is the passageway for air between the oropharynx and trachea
Attached to hyoid bone superiorly and trachea inferiorly
Cartilage, CT, skeletal muscle, vocal cords, epiglottis

Question 7

Explain the division of the trachea into right and left bronchus.

Answer 7

The trachea divides into two main bronchi at a point called the carina, located T5
The division of the trachea into the right and left main bronchi occurs at an angle, with the right main bronchus being slightly wider, shorter, and more vertical than the left one. This asymmetry is due to the space occupied by the heart in the left side of the thoracic cavity.

Question 8

Explain the subdivision of each main bronchus

Answer 8

Each bronchus subdivides into lobar bronchi.
The right main bronchus subdivides into three lobar bronchi, each supplying a specific lobe of the right lung: superior, middle, and inferior lobar bronchi.
The left main bronchus, being narrower to accommodate the heart, only subdivides into two lobar bronchi, superior and inferior lobar bronchi.
Each lobar bronchus further divides into segmental (tertiary) bronchi, which supply individual bronchopulmonary segments within each lobe of the lung.
Then divides into terminal bronchioles and alveoli.

Question 9

Describe the structure of the trachea.

Answer 9

Lined with a typical respiratory mucosa - pseudo-stratified columnar ciliated epithelium with goblet cells

Lamina propria contains a large amount of elastic fibres

Submucosa - contains seromucous glands

Adventitia - Loose connective tissue reinforced by 16-20 C-shaped rings of cartilage

Question 10

Describe the pleura.

Answer 10

The pleura (serous membrane/serosa) is a smooth tissue membrane consisting of two layers of mesothelium, which secrete serous fluid.
The parietal pleura covers the thoracic wall and the diaphragm and extends around the heart to the hilum of the lung
The visceral pleura is a continuation of the parietal pleura and covers the surface of the lung extending into the fissures
Between the two pleurae is the pleural cavity filled with pleural fluid
Provides protection from friction against chest wall