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Introduction to RespirationThe Mammalian Respiratory System

RespirationRefers to all parts of the process that supplies oxygento body cells and rids the bodyof carbon dioxideIn mammals, respiration can be subdivided into the following:BreathingExternal respirationInternal respirationCellular respiration

BreathingCan be further divided intoInspiration: the act of taking air into the lungsExpiration: the act of breathing out

Internal & External RespirationThe mechanism of the internal and external respiration depends on diffusion theory indicating that the substance diffuses from the area with high density to the lower oneExternal RespirationThe exchange of oxygen and carbon dioxide between air and blood

Internal RespirationThe exchange of oxygen and carbon dioxide between blood and the cells of the surrounding tissue

Cellular RespirationThe complex series of chemical reactions that take place mainly in the mitochondria of cellsThe Respiratory TractInvolved in the process of respiration

Further divided into two parts:1. The upper respiratory tract2. The lower respiratory tract

The upper and lower respiratory tracts make up our whole respiratory system and work in a synchronizing pattern to make it possible to breathe.The Upper Respiratory TractThe upper respiratory tract refers to the following parts of the respiratory system:

The nasal passagesGlottisPharynxLarynxTracheaThe Lower Respiratory TractThe lower respiratory tract refers to the following parts of the respiratory system:

Larynx (voice box)Trachea (wind pipe)bronchial tubesBronchioleslungs

Mammalian Respiratory SystemThe Upper Respiratory Tract

The Nasal PassagesThe air first enters the nostrils In humans and many other animals, it can also enter via the mouthAir is conducted into the hollow nasal passagesThe nasal chambers are protected by turbinatesTurbinatesThin bonesHang suspended from the nasal chambersTheir presence increases the surface area of these chambersTurbines covered with a thin membrane that secret mucusMucus helps moisten the airTurbinates and linings of the nasal chambers are supplied with capillariesThis helps to warm the incoming air and to increase the air humidityThe warming and moistening helps to protect the lung tissues

TurbinatesTurbinates

PharynxThe air then passes through the pharynxThe pharynx is part of the digestive system and respiratory system of many organismsSection of the alimentary canal Connects the mouth and nasal cavity to the larynx and esophagous

PharynxSo the pharynx is a common channel that conducts both air and food. Because of these two functions, the pharynx must open to allow air and food to pass through, and at the same time, it must be able to squeeze the food down into the oesophagus. The pharynx performs these functions simultaneously at mealtimes.

GlottisThe opening of the tracheaThe passageway conducting air to the lungsThe area where the vocal cords are located

EpiglottisThe glottis opening is protected by epiglottisFlap-like structure attached to the root of the tongue helps to prevent food from entering the trachea

LarynxBiologically, the larynx evolved as a valve to protect the airway and lungs. Thus, it is positioned where the airway and the esophagus separate.Also know as voice boxContains the two folded structures of the vocal cords (vocal folds)

LarynxVocal fold vs. Vocal cordVocal fold is the modern term for vocal cord. Vocal cord suggests a band or string suspended in the air that vibrates when it is plucked or struck. However, the vocal fold is a part of a muscle on the side of the larynx, covered with special tissues that can vibrate at a high speed.

Vocal FoldsThe vocal folds are a pair of tissue that stretch across the top of the trachea The vocal folds, together with the muscles and cartilages that support them, are known as the larynx Voice is produced by vibration of the vocal folds.

Vocal FoldsWhen we breathe normally, there is a large gap between the two foldsWhen we prepare to speak, muscles around the larynx contract, bringing the folds closer togetherThe passage of air through this narrow space causes the folds to vibrate producing a sound

Pitch and SoundThe pitch of the sound can be changed by both: GlottisYou can change the pitch of the sound you make by expanding or tightening the glottisThe tighter the glottis, the higher the sound

Vocal FoldsIn addition to opening and closing, the vocal folds are able to lengthen and shortenThe pitch of the sound varies with the length of the vocal foldsA long fold produces a low soundA shorter fold produces a higher soundAt puberty, the vocal folds of males grow quicklyThe vocal folds in men tend to be longer than in women, therefore men have a deeper voice

TracheaAfter passing through the larynx, air goes down the tracheaFlexible tube, in mammals, called the wind pipeSupported by semicircular cartilage ringsThese rings prevent the trachea from collapsingRings arranged in a way that do not interfere with the passage of food down the esophagus

The upper respiratory tractThe nasal and other passages of the upper respiratory tract are lined with ciliated cells that secrete mucus

Ciliated cellsThe mucus traps foreign particles such as dust and bacteria

Cilia help these foreign materials to move back into the nose and throat where they can be expelled by coughing or sneezing

Mammalian Respiratory SystemThe Lower Respiratory Tract

The Lower Respiratory TractThe trachea branches into two smaller passageways called bronchi (singular= bronchus)One bronchus enters each lungEach bronchus subdivides many times to produce bronchiolesBronchioles are a network of finer tubesLike the trachea and nasal passages, the bronchi and bronchioles are also lined with ciliated cells

The Lower Respiratory TractEach bronchiole ends in a grape-like cluster of tiny sacs called alveoli (singular= alveolus)

AlveoliAlveoli are always kept moistActual gas exchange of gases takes place in alveoliThe walls ofeach sac is onecell thick and is adjacent to a network of tinycapillaries

AlveoliThe network of capillaries are the site for gas exchange of oxygen and carbon dioxideMost gas exchange takes place through simple diffusion30% of gas exchange is through facilitated diffusionThis allows blood to take up oxygen more quickly than would otherwise

Capillary NetworkBronchioles and alveoli are kept in a permanent position by elastic connective tissueAlveoli are lined with a film that contains lipoprotein, which helps alveoli from collapsing

CO2 rich bloodO2 rich bloodGas ExchangeThe carbon dioxide and oxygen concentration in the lung capillary blood is higher and lower than in the air of the pulmonary alveoliso the carbon dioxide diffuses from the blood to the pulmonary alveoli and the oxygen diffuses from pulmonary alveoli to the blood.

In Alveoli: high [O2]Low [CO2] In Blood: Low [O2]High [CO2] Gas ExchangeThe condition between the body tissue is just reverseThe carbon dioxide and oxygen concentration in the blood is respectively lower and higher than in the body tissuesSo the carbon dioxide diffuses from the body tissue to the blood and the oxygen diffuses from the blood to the body tissues.

In Blood: High [O2]Low [CO2]In Body cells and tissues: Low [O2]High [CO2] LungsEach lung is divided into lobesThe right lung has three lobesThe left lung has only two lobesA lobe is made up of a number of lobules, each with its own bronchiole.

Right LungLeft LungPleuraThe lungs are enveloped in layers of tissue called pleura (singular= pleuron)Pleura is a flexible membrane containing the lungs andAllowing the lungs to expand during inspiration and contract during expirationEach pleuron is made up of two layers separated by a thin film of lubricating fluid

Lubricating fluidPleurisyCondition occurs when the pleura become inflamedOften caused by certain respiratory conditionsTypically as a secondary infection related to pneumonia or other thoracic diseasesPleurisy is not a disease, but rather a chest pain caused by the lung and chest wall rubbing against each other.Can be extremely painfulEnvironmental factors such as asbestos in the air can also cause pleurisy.

Describe the path of air into the bodyStructureDescriptionFunctionNasal CavitiesHollow spaces in noseFilter, warm, moisten airPharynxChamber connecting oral and nasal cavities to larynxConnection to surrounding regionsGlottisOpening to larynxAir passage to larynxLarynxOrgan containing vocal cordsSound productionTracheaFlexible tube linking larynx and bronchiPassage of air to bronchiBronchiTracheal divisions to lungsPassage of air to lungsBronchiolesBranched tubes from bronchi to alveoliPassage of air to each alveolusLungsSoft, spongy organs in thoracic cavityGas exchange