The Respiratory System

Chapter 13

Organs of the Respiratory System

Nose Pharynx Larynx Trachea Bronchi & their smaller branches Lungs

– Alveoli: air sacs where the ONLY gas exchange of the respiratory system to the blood takes place. All other structures are only conducting passageways which allow air to reach the lungs!

Functions of the Respiratory System

Purify Humidify Warms air coming into the lungs

These functions allow air coming into the lungs to have fewer irritants and to function properly.

The NOSE

The only external visible part of the respiratory system During breathing air enters the nose by passing through

the external nares/nostrils The interior of the nose consists of a nasal cavity divided

by a nasal septum Olfactory receptors: located in the mucosa in the slitlike

superior part of the nasal cavity, just below the ethmoid bone

The NOSE

Respiratory Mucosa: composes the rest of the mucous lining of the nasal cavity, rests on a network of thin-walled veins that warm air as it flows past

The other mucosa glands moisten air and trap incoming bacteria and other foreign debris

Ciliated cells: in the nasal mucosa they create a current that moves contaminated mucus posteriorly towards the pharynx where it is swallowed and digested by stomach juices.

The NOSE

Conchae: consists of 3 mucosa covered projections/lobes on the lateral walls of the nasal cavity. Their function is to increase the surface area of the mucosa exposed to air. They also create movement of air in the nasal cavity and trap and prevent particles to be deflected from the mucus lined surfaces and prevent them from reaching the lungs.

The NOSE

Palate: separates the nasal cavity from the oral cavity below it.– Hard Palate: anterior portion of the palate which is

supported by bone– Soft Palate: posterior portion of the palate which is

completely unsupported. – Cleft palate: Genetic defect where the bones forming

the palate fail to form completely and fuse medially. It results in breathing difficulty and problems with oral cavity functions such as chewing and speaking.

The NOSE

Paranasal sinuses: located in the frontal, sphenoid, ethmoid and maxillary bones. These sinuses lighten the skull and act as resonance chambers for speech. They also produce mucus that drains into the nasal cavities. Blowing the nose creates a suctioning affect which clears the sinuses.

Nasolacrimal ducts: drain tears from the eyes and also empty into the nasal cavity.

Infections of the Nasal Cavity

Rhinitis:– Inflammation of the nasal mucus. – Excessive mucus produced will result in nasal congestion and

postnasal drip. – Because the nasal mucus is continuous through the respiratory

tract infection can spread

Sinusitis:– Inflamed sinuses– Very difficult to treat and causes changes in the voice– When the sinuses are completely blocked with mucus or

infectious matter the air is absorbed and a sinus headache occurs.

The THROAT

Pharynx: muscular passageway about 5 inches long and is most commonly called the throat. It serves as a passageway for air and food.

Nasopharynx: the superior portion of pharynx, first place for air to enter from the nasal cavity before it descends down the …

Oropharynx: anterior portion. Food also passes down this portion along with the air.

The THROAT

Layngopharynx: area where food and air travel. Food is directed posteriorly to enter the esophagus and air will travel down the..

Larynx: inferior portion of Pharynx Auditory tube: drains the middle ear and

opens up into the nasopharynx. Since the two are connected an ear infection maybe turn into a sore throat or vice versa

The THROAT

Tonsils: clusters of lymphatic tissue found in the pharynx.– Pharyngeal tonsils: most commonly called adenoids

are located high in the nasopharynx. When they become inflamed it causes the person to breathe only through the mouth

– Palatine tonsils: are in the oropharynx at the end of the soft palate

– Lingual tonsils: are found at the base of the tongue

The THROAT

Larynx: voice box, routes air and food into the proper chambers and plays a small role in speech. Located inferiorly to the pharynx it is formed by 8 rigid hyaline cartilages and spoon shaped flap of elastic cartilage.

Epiglottis: the flap of elastic cartilage. Protects the superior opening of the larynx and when we are not swallowing allows air into the lower respiratory passages. When we are swallowing or drinking however the epiglottis tips up and closes off the larynx and routes food towards the esophagus. If food or water does enter it results in a cough reflex.

The THROAT

Thyroid cartilage: large mass of hyaline cartilage, is shield shaped and protrudes anteriorly and is referred to as the “Adams Apple”

Vocal folds: part of the mucus membrane of the larynx which vibrate with expelled air allowing us to speak

Glottis: the slitlike passageway between the vocal folds

The THROAT

Trachea: windpipe. It is the only way air can enter the lungs. Air enters from the larynx and travels down its length to the level of the 5th thoracic vertebrae. It is lined with ciliated mucosa which propels the mucous full of dust particles and debris away from the lungs

The trachea is rigid and its walls are supported by a c-shaped ring of hyaline cartilage. The open part of the rings allows the esophagus to expand anteriorly when we swallow a large piece of food. The solid portions of the wall keep the trachea open in spite of pressure changes which occur during breathing.

The THROAT

Primary Bronchi: there is a right and left primary bronchi which are formed by the division of the trachea. Each bronchi runs obliquely until it enters the lung on its side.– Right pulmonary bronchi: is wider, shorter and

straighter than the left and is a common site for an inhaled object to become lodged. By the time air enters the bronchi it is warmed, cleansed and humidified. The smaller divisions of bronchi within the lungs are the direct routes to the air sacs

The LUNGS

Paired large organs which occupy the entire thoracic cavity except for the central area which contains the heart.– Apex: narrow superior portion of each lung located just

beneath the clavicle– Base: broad area of the lungs which rests on the

diaphragm

Each lung is divided into lobes the right has 3 and the left has 2.

The LUNGS

Pulmonary/Visceral Pleura: viscera covering the surface of each lung.

Parietal Pleura: covers the walls of the thoracic cavity Pleural Membranes: produces a slippery serous secretion

that allows the lungs to glide easily over the thorax wall during breathing and causes the two pleural layers to cling together

Pleurisy: inflammation of the pleura caused by decreased secretion of pleural fluid causing the surfaces to become dry and rough causing friction and stabbing pain with each breath. It may also be caused by an excess of secretion of pleural fluid which puts pressure on the lungs making it hard to breathe.

The LUNGS

Bronchioles: the smallest branch of the conduction pathway

Bronchial or respiratory tree: the network of branching bronchi into smaller and smaller branches until they become bronchioles. All of the branches except for the bronchioles have reinforcing cartilage in their walls.

The LUNGS

Terminal Bronchioles: Lead into … Respiratory Zone: includes the respiratory

bronchioles, alveolar ducts, alveolar sacs, and alveoli. This is the ONLY site for gas exchanges. The structures in the respiratory zone eventually become …

Alveoli: small air sacs where gas exchange takes place. Alveoli make up the bulk of the lungs and the rest is mostly air space.

The LUNGS

Respiratory Membrane: the air-blood barrier. Made up of alveolar and capillary walls. Air passes by on one side and blood flows past on the other. The gas exchange occurs by simple diffusion through the respiratory membrane. Oxygen passes from the alveolar air into the capillary blood and the carbon dioxide leaving the blood to enter the gas filled alveolus.

The LUNGS

Alveolar Walls: composed of a single layer of squamus epithelial cells which are very thin. The external surface of the walls is covered with a web of pulmonary capillaries.

Alveolar pores: Connect the air sacs and provide an alternate rout for air to reach the alveoli when their bronchioles are clogged.