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Physiology of respiration Submitted by:- Tanmay Srivastava & Nidhi Singh

Presentation

In general respiration is:-

Exchange of gases from:-Atmosphere to blood &

Blood to tissues.

What is respiration?

“Respiration is the process by which oxygen from the lungs or gills is carried by the blood to the tissue; and carbon dioxide formed in the tissue by metabolic activities is carried by the blood to the lungs or gills and is expired out.”

What is respiration?

1) External respiration or lung ventilation, in which exchange of air between external environment and the lung alveoli.

2) Diffusion of gases in lungs, in which exchange of gases (O2 and CO2) between alveolar air and blood.

3) Transport of gases (O2 and CO2) through blood.

Basic phases in the process of respiration: (In Humans )

4) Diffusion of gases in the tissues, in which exchange of gases between blood and tissues.

5) Cellular respiration, in which consumption of O2 by cells in metabolism and liberation of carbon dioxide after metabolism

structural aspects considered in respiration process.

The conduction portionThe exchange portionThe structures involved with

ventilationSkeletal & musculaturePleural membranesNeural pathways

All divided intoUpper respiratory tract

Entrance to larynxLower respiratory tract

Larynx to alveoli (trachea to lungs)

Schematic View of Respiration

External Respiration

Internal Respiration

Respiratory PassagesNOSTRIL

NASAL CAVITY

PHARYNX

LARYNX

TRACHEA

BRONCHUS

BRONCHIOLES

ALVEOLI

The nasal cavities are lined with mucous membrane which is highly vascular. It is continuous with the lining of the pharynx and with the mucous membrane of the sinuses which open into the nasal cavity.

As air passes through the nose it is filtered by the hairs contained in the vestibule, warmed by contact with the fairly extensive mucous surface, and moistened by evaporation of moisture from this surface.

Respiratory tract

Upper respiratory passage in human

Pharynx lies behind the nose (the nasopharynx).It is a muscular tube arises from base of skull to its junction with the oesophagus

The posterior nares are the openings from the nasal cavities to the nasopharynx.

The larynx lies in front of the lowest part of the pharynx which separates it from the vertebral column, extending from the pharynx to the level of 6th cervical vertebra. It is the upper prominent part of the wind pipe and opens into the trachea below.

The Trachea or wind pipe is about 10 cm (4 inches) long. It extends from the larynx to about the level of the 5th thoracic vertebra, where it divides into two bronchi

The bronchi are formed by the bifurcation of the trachea at the level of the 5th thoracic vertebra, are similar in structure to the trachea.

Bronchi are further divide into bronchioles and alveolar duct.

Each alveolar duct open into a large alveolar sac. Many small alveoli open into each alveolar sac.

Muscles:-DIAPHRAGMLarge sheet of muscle that can contract and or relax.

Skeletal and muscles involve in respiration…..

Intercoastel muscles

Internal Intercoastal muscle external Intercoastal muscles

We generally breathe with the diaphragm and external intercostals muscles only

it is only when exercising that we use the other muscles – our internal intercostals and the muscles of the abdominal wall to really force air out.

RibsThe thoracic cage is

formed by the twelve thoracic vertebrae at the back, the sternum in front, and the twelve pairs of ribs at sides, which encircle the trunk from the vertebral column behind to the sternum in front

It is of two type, namely :-

External &

Internal

Physiology of respiration

The process of intake of fresh air from the atmosphere into the lungs and elimination of used air from lungs to external environment is known as breathing.

The breathing is a mechanical process, which provides oxygen-rich fresh air to the lungs for pulmonary respiration.

External respiration

In human, the breathing is about 16 times per minute. The process of breathing is completed in two phases, i.e., inspiration and expiration

In inspiration, the ribs are elevated and the diaphragm contracted and flattened, the chest cavity is enlarged.

Low air pressure inside the lungs in comparison to atmospheric pressure makes air passes through the air passages way to lungs.

InspirationInternal respiration

In expiration, the ribs diaphragm and chest cavity return to its original position and its makes decrease in volume of chest cavity which makes air moves out from the lungs.

Expiration

Changes in the intrapleural pressure are responsible for air entering and leaving the lungs. The process of inspiration and expiration depends on the contraction and relaxation of intercostals muscles

The expansion of lungs during inspiration follows the enlargement of the thoracic cavity in all its diameters by the contraction of the respiratory muscles.

There are eleven pairs intercostal muscle present in between the ribs, which are arranged in two layer viz.

External intercostal muscles Internal intercostal muscles

Mechanism of breathing

When the external intercostal muscles contract, the ribs become straight and the sternum is shifted.

This increases the volume of thoracic cavity which makes an increase in lungs volume and cause inspiration.

when these external intercostal muscles relax, all the structure return to there normal position and expiration takes place

During expiration diaphragm relaxes, its dome moves upwards.

Eupnea- normal quite breathingHyperpnea- increased in respiratory rate/depth/both.Dyspnea- irregularities of respiration or

difficult breathing.Polypnea- rapid, shallow breathing.Apnea- cessation of respiration or no breathing.

Types of breathing:-

Process of gases exchange:-

During breathing gases always tend to diffuse from high partial pressure to low partial pressure.

The oxygen has higher partial pressure in alveolar air than blood, thus oxygen diffused into blood.

Whearas carbon dioxide has higher partial pressure in blood than in alveolar air, thus carbon dioxide diffused out into alveolar air.

The mammalian blood possesses respiratory pigment haemoglobin, which carries oxygen from lung alveoli and forms oxy haemoglobin.

Each molecule of haemoglobin possesses 4 atoms of iron and each iron carries one molecule of oxygen.

About 97% oxygen is carried by R.B.Cs. In the form of oxyhaemoglobin.

Rest 3% oxygen is transported by plasma in dissolved state.

Transport of gases:-

Diseases affecting air passage:-1) Asthma: The airways are persistently

inflamed, and may occasionally spasm, causing wheezing and shortness of breath.

Allergies, infections, or pollution can trigger asthma's symptoms.

2) Chronic obstructive pulmonary disease (COPD): Lung conditions defined by an inability to exhale normally, which causes difficulty breathing.

Respiratory diseases

Pneumonia: An infection of the alveoli, usually by bacteria.

Tuberculosis: A slowly progressive pneumonia caused by the bacteria Mycobacterium tuberculosis.

Lung cancer: has many forms, and may develop in any part of the lungs. Most often this is in the main part of the lung, in or near the air sacs. The type, location, and spread of lung cancer determines the treatment options.

Lung Diseases Affecting the Air Sacs (Alveoli)

Acute respiratory distress syndrome (ARDS): Severe, sudden injury to the lungs caused by a serious illness. Life support with mechanical ventilation is usually needed to survive until the lungs recover.

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