The Respiratory System

By Shaik Afsar, M.Pharm, (Ph.D)Department of Pharmacology

Gokula Krishna College of Pharmacy, Sullurpet, Nellore Dist

The Respiratory System

The human respiratory system allows one to obtain oxygen, eliminate carbon dioxide.

Breathing consists of two phases, inspiration and expiration Inspiration- the process of taking in air Expiration- the process of blowing out air

Pulmonary ventilationAir moves in and out of lungsContinuous replacement of gases in alveoli (air sacs)

External respirationGas exchange between blood and air at alveoliO2 (oxygen) in air diffuses into bloodCO2 (carbon dioxide) in blood diffuses into air

Transport of respiratory gasesBetween the lungs and the cells of the bodyPerformed by the cardiovascular systemBlood is the transporting fluid

Internal respirationGas exchange in capillaries between blood and tissue cellsO2 in blood diffuses into tissuesCO2 waste in tissues diffuses into blood

Respiration Includes

The organs of the respiratory system are:

Nose

Pharynx (Throat)

Larynx (Voice box)

Trachea (Wind Pipe)

Two bronchi (one bronchus to each lung)

Bronchioles and smaller air passages

Two lungs and their coverings, the pleuramuscles of respiration — the intercostal muscles and the diaphragm.

THE PARTS OF RESPIRATORY SYSTEM CAN BE CLASSIFIED ACCORDING TO EIGHTER STRUCTURE OR FUNCTION

Structurally:Upper respiratory system

Lower respiratory system

Functionally:Conducting zone

Respiratory Zone

Components of the Upper Respiratory Tract

Includes:Nose

Pharynx

Associated

structures

Functions of Upper Respiratory Tract

Passageway for respiration Receptors for smell Filters incoming air to filter larger foreign

material Moistens and warms incoming air

Components of the Lower Respiratory Tract

Functions:Larynx: maintains an open airway, routes food

and air appropriately, assists in sound production

Trachea: transports air to and from lungsBronchi: branch into lungsLungs: transport air to alveoli for gas exchange

Functions of Lower Respiratory Tract

Conducting portion (transports air).

Includes the nose, nasal cavity, pharynx, larynx,

trachea, and progressively smaller airways, from the

primary bronchi to the terminal bronchioles

Respiratory portion (carries out gas exchange).

Composed of small airways called respiratory

bronchioles and alveolar ducts as well as air sacs

called alveoli

NOSE AND NASAL CAVITY

Passage of Air through Nose

Internal nares (Nostrils) - opening to exterior

External nares (Nostrils)-opening to pharynx

Nasal conchae - folds in the mucous membrane that increase air

turbulence and ensures that most air contacts the mucous membranes

Parts of Nose

rich supply of capillaries warm the inspired air olfactory mucosa – mucous membranes that contain smell receptors respiratory mucosa – pseudostratified ciliated columnar epithelium containing goblet cells that secrete mucus which traps inhaled particles, lysozyme kills bacteria and lymphocytes and IgA antibodies that protect against bacteria

Linings of Nose

Provides airway

Moistens and warms air

Filtering and cleaning air

Humidification

Resonating chamber for speech

Olfactory receptors

Rhinoplasty: surgery to change shape of external nose

Functions of Nose

Para nasal Sinuses

Four bones of the skull contain paired air spaces called the Para

nasal sinuses - frontal, ethmoidal, sphenoidal, maxillary

Decrease skull bone weight

Warm, moisten and filter incoming air

Add resonance to voice.

Communicate with the nasal cavity by ducts.

Lined by Pseudo stratified ciliated columnar epithelium.

Can get infected: sinusitis

PharynxThe pharynx is a tube 12 to 14 cm long that extends from the base of the skull to the level of the 6th cervical vertebra. It lies behind the nose, mouth and larynx and is wider at its upper end.Common space used by both the respiratory and digestive systems. Commonly called the throat. Originates posterior to the nasal and oral cavities and extends inferiorly near the level of the bifurcation of the larynx and esophagus. Common pathway for both air and food.

Pharynx is divided into three parts:

Nasopharynx,

Oropharynx and

Laryngopharynx.

Houses tonsils (they respond to inhaled antigens)

Uvula closes off nasopharynx during swallowing so food

doesn’t go into nose

Epiglottis posterior to the tongue: keeps food out of

airwayLined with stratified squamous epithelium for protection

Functions of Pharynx

Passageway for air and food.

Warming and humidifying.

Taste.

Hearing.

Protection.

Speech.

Larynx (Voice Box)

Extends from the level of the 4th to the 6th cervical vertebrae

Attaches to hyoid bone superiorly Inferiorly is continuous with trachea (windpipe)Three functions:

1. Produces vocalizations (speech)2. Provides an open airway (breathing)3. Switching mechanism to route air and food into

proper channelsClosed during swallowingOpen during breathing

The larynx is composed of several irregularly shaped

cartilages attached to each other by ligaments and membranes.

The main cartilages are:

• 1 thyroid cartilage

• 1 cricoid cartilage

• 2 arytenoid cartilages

• 1 epiglottis

Hyaline Cartilage

Elastic Cartilage

Sound Production

Functions

Production of sound

Speech

Protection of the lower respiratory tract

Passageway for air

Humidifying, filtering and warming

Trachea

A flexible tube also called windpipe.

Extends through the mediastinum and lies anterior to the

esophagus and inferior to the larynx.

Anterior and lateral walls of the trachea supported by 15 to

20 C-shaped tracheal cartilages.

Cartilage rings reinforce and provide rigidity to the tracheal

wall to ensure that the trachea remains open at all times

Posterior part of tube lined by trachealis muscle

Lined by ciliated pseudostratified columnar epithelium.

At the level of the sternal angle, the trachea

bifurcates into two smaller tubes, called the right

and left primary bronchi. Each primary bronchus projects laterally toward

each lung.

Functions

Support and patency

Mucociliary escalator

Cough reflex

Warming, humidifying and filtering of air

Bronchi and bronchioles

The two primary bronchi are formed when the trachea divides, i.e. about the level of the 5th thoracic vertebra.The right bronchus. This is wider, shorter and more vertical than the left bronchus.It is approximately 2.5 cm long. After entering the right lung at the hilum it divides into three branches, one to each lobe. Each branch then subdivides into numerous smaller branches.The left bronchus. This is about 5 cm long and is narrower than the right. After entering the lung at the hilum it divides into two branches, one to each lobe. Each branch then subdivides into progressively smaller tubes within the lung substance.

Structure

The bronchi are composed of the same tissues as the

trachea. They are lined with ciliated columnar

epithelium.

The bronchi progressively subdivide into

bronchioles

terminal bronchioles,

respiratory bronchioles,

alveolar ducts and

finally, alveoli.

Functions

warming and humidifying

support and patency

removal of particulate matter

cough reflex.

LungsThere are two lungs, one lying on each side of the midline in the thoracic cavity. They are cone-shaped and are described as having an apex, a base, costal surface and medial surface.The Right lung is divided into three lobes:SuperiorMiddleInferiorThe Left lung is divided into two lobes:SuperiorInferior

Pleura and Pleural cavity

The pleura consists of a closed sac of serous membrane (one for each lung) which contains a small amount of serous fluid. The lung is invaginated into this sac so that it forms two layers: one adheres to the lung and the other to the wall of the thoracic cavity

The Visceral Pleura

The Parietal Pleura

The Pleural cavity