‘A RESPIRATORY SYSTEM IS A GROUP OF ORGANS WORKING TOGETHER TO

BRING ABOUT THE EXCHANGE OF OXYGEN AND CARBON DIOXIDE WITH

THE ENVIRONMENT’

The Respiratory System may be divided into the

UPPER RESPIRATORY TRACT AND THE

LOWER RESPIRATORY TRACT

THE UPPER RESPIRATORY TRACT

CONSISTS OF THE PARTS OUTSIDE THE

THORACIC (CHEST) CAVITY:

THE AIR PASSAGES OF THE NOSE, NASAL CAVITIES, PHARYNX (WINDPIPE), LARYNX

(VOICE BOX), AND UPPER TRACHEA.

THE LOWER RESPIRATORY TRACT

CONSISTS OF THE PARTS FOUND IN THE THORACIC (CHEST) CAVITY

THE LOWER TRACHEA AND THE

LUNGS THEMSELVES

Air ENTERS the Respiratory System through the Mouth or Nose.

They process the air that you breathe before it enters your lungs. Most of this activity takes place in and on the turbinates,

located on the sides of the nasal passages.

In an adult, 18,000 to 20,000 litres of air pass through the nose each day.

In humans, the turbinates divide the nasal airway into three groove-like air passages –and are responsible for forcing inhaled air to flow in a steady, regular pattern around the largest possible surface of cilia and climate controlling tissue.

In anatomy, a turbinate (or nasal concha) is a long, narrow and curled bone shelf which protrudes into the passage of the nose. Turbinate bone refers to any of the scrolled

spongy bones of the nasal passages in humans.

• When you breathe in through your nose or mouth, the air is "filtered" through natural lines of defense that protect against illness and irritation of the respiratory

tract.

• Nasal hairs (vibrissae) at the opening of the nostrils trap large particles of dust that might otherwise be inhaled.

The NOSE

• The entire respiratory system, as with the reproductive, digestive, and urinary

systems, is lined with a mucous membrane that secretes mucus. The mucus traps smaller particles like pollen or smoke.

• Under the mucous membrane there are a large number of capillaries. The blood within these capillaries helps to warm the air as it passes through the nose

• Hair like structures called cilia line the mucous membrane and move the particles trapped in the mucus out of the nose.

turbinates

The nose serves three purposes. • FILTER THE AIR prevents damage to the delicate tissues that form the Respiratory System.

• WARM THE AIRIncreasing the amount of Water Vapour the air entering the Lungs contains.

• PROVIDE MOISTURE (WATER VAPOR OR HUMIDITY) TO THE AIR. This helps to keep the air entering the nose from Drying out the Lungs and other parts of our Respiratory System.

PHARYNX (WINDPIPE)

Air travels from the nasal passages to the pharynx, or more commonly known as the throat

The pharynx roat, is a passageway that extends from the base of the skull to the level of the sixth cervical vertebra.

The epiglottis drops downward to prevent food from entering the larynx and trachea in order to direct the food into the oesophagus .

Epiglottis

The epiglottis guards the entrance of the glottis, the opening between the vocal folds.

It is normally pointed upward, but during swallowing, elevation of the hyoid bone draws

the larynx upward; as a result, the epiglottis folds down to a more horizontal position.

In this manner it prevents food from going into the trachea and instead directs it to the

esophagus, which is more posterior.

From the Pharynx, the air moves through the LARYNX (Voice Box)

Inside, and stretched across the Larynx are two highly elastic folds of tissue (Ligaments) called the VOCAL CORDS.

Air rushing through the voice box causes the vocal cords to vibrate producing sound waves.

From the Larynx, the Warmed, Filtered, and Moistened air passes downward into the Thoracic Cavity through the Trachea.

LARYNX

TRACHEA • The Walls of the

Trachea are made up of C-Shaped rings of tough flexible Cartilage. 

These rings of cartilage Protect the Trachea, make it

Flexible, and keep it from Collapsing or over expanding. (protect it)

The Cells that line the trachea produce Mucus; the mucus helps to capture things still in the air (Dust and Micro organisms), and is swept out of the air passageway by tiny Cilia into the Digestion System.

TRACHEA

SEA LION

Within the Thoracic Cavity, the Trachea divides into TWO Branches, the Right and Left BRONCHI. Each BRONCHUS enters the LUNG on its

respective side

They are separated from each other by the mediastinum and the heart. The upper part of the lung near the collarbone or clavicle is called the apex and the broad lower part is called the

base. The base of each lung rests on the diaphragm below.

MEDIASTINUM

The mediastinum is also called the interpleural space. It is situated between the lungs. The mediastinum contains: the thymus gland, heart, aorta and it's branches, pulmonary arteries

and it's veins, superior and inferior vena cava, esophagus, trachea, thoracic duct, lymph nodes and vessels.

THE LUNGS

The right lung is larger and broader than the left lung. This is due to the shape and location of the heart. The right lung is also shorter due to the diaphragm's upward

displacement to accommodate the liver.

The right lung is divided into three lobes or parts; superior, middle and inferior.

The left lung is divided into two lobes; superior and inferior. The left lung is smaller and narrower than the right lung. The concave area occupied by the heart on the left

side of the lung is called the cardiac impression.

Lining the entire cavity and encasing the Lungs are PLEURA MEMBRANES that secrete a Mucus that decreases friction from the movement of the Lungs during Breathing

The pleural membranes are the serous membranes of the thoracic cavity. The parietal pleura lines the chest wall. The visceral pleura is actually on the surface of

the lungs.

Between the pleural membranes is a serous fluid which prevents friction and keeps the two membranes together during breathing.

• Unfortunately, there may be an occasion where the pleural cavity may fill up with an enormous amount of serous fluid. This would occur when there is an inflammation of the pleura of pleurisy. The excess fluid can compress or even at times collapse the lung.

•This extra fluid can make it very difficult to breathe. To alleviate such pressure, sometimes a procedure called a thoracentesis is performed. This is where a hollow, tube like instrument is inserted into the thoracic and pleural cavities to drain the fluid.

The further branching of the BRONCHIAL TUBES is often called the BRONCHIAL TREE

Imagine the Trachea as the trunk of an upside down tree with extensive branches that become smaller and smaller; these smaller branches are the BRONCHIOLES.

Bronchus (Right- or Left- Primary Bronchus) -Lobar Bronchus - Segmental Bronchus –Bronchiole - Terminal Bronchiole - Respiratory Bronchiole - Alveolar Duct - Alveolar Sac

Alveolus

AsthmaAsthma is an inflammatory disorder of the airways, characterized by periodic attacks of

wheezing, shortness of breath, chest tightness, and/or coughing.Three things make it harder to breath during an asthma attack -- the inflammation (swelling) of

the lining of the airways, the tightening of the muscles around the airways, and fluid/mucus filling the airways. These factors reduce airflow and produce the characteristic wheezing sound

Alveolar Sac / Alveolus

The lungs contain about 300 million alveoli, representing a total surface area of 70-90 metres squared, each wrapped in a fine mesh of capillaries.

Total surface area of lungs

(including alveoli)

Alveolar Sac / Alveolus

Red blood cells transit the alveolar capillaries in about 3/4 of a second.

Oxygen dissolved in the blood may diffuse into red blood cells and bind to haemoglobin. Binding of oxygen to haemoglobin allows a greater amount of oxygen to be transported in the blood. Although carbon dioxide and oxygen are the most important molecules exchanged

‘moving from an area of high concentration to an area of low concentration of that matter’

Diffusion

When alveolar pressure is negative, as is the case during inspiration, air flows from the higher pressure at the mouth down the lungs into the lower pressure in the alveoli. When alveolar pressure is positive, which is the case during expiration, air flows out

Oxygen moves from the alveoli (high oxygen concentration) to the blood (lower oxygen concentration, due to the continuous consumption of oxygen in the body). Conversely, carbon dioxide is produced by metabolism and has a higher concentration in the blood than in the air

Partial Pressure & Diffusion

‘moving from an area of high

concentration to an area of low

concentration of that matter’

So Why Gas Exchange Is So Good In The Lungs?

• Large Surface Area

• Good Capillary Network

• 300 Million Alveoli

• Emphysema is characterized by loss of elasticity of the lung tissue; destruction of structures supporting the alveoli; and destruction of capillaries feeding the alveoli.

• Bronchitis The earliest clinical feature of bronchitis is increased secretion of mucus by submucousal glands of the trachea and bronchi. Damage caused by irritation of the airways leads to inflammation and infiltration of the lung tissue by neutrophils. The neutrophils release substances that promote mucosal hyper secretion

COPDchronic obstructive pulmonary disease