RESPIRATION SYSTEMRESPIRATION SYSTEM

IN HUMANIN HUMANGASEOUS EXCHANGE – RESPIRATORY SYSTEMGASEOUS EXCHANGE – RESPIRATORY SYSTEM

HUMAN RESPIRATION SYSTEMHUMAN RESPIRATION SYSTEM

A.A. Respiration organs.Respiration organs.B.B. Breathing mechanism.Breathing mechanism.C.C. Internal respiration.Internal respiration.

GASEOUS EXCHANGE IN HUMANGASEOUS EXCHANGE IN HUMAN

GASEOUS EXCHANGE OCCURS IN THE RESPIRATORY SYSTEMGASEOUS EXCHANGE OCCURS IN THE RESPIRATORY SYSTEM

The most important are the two lungs. Each lung is filled The most important are the two lungs. Each lung is filled with many tiny air spaces called air sacs or with many tiny air spaces called air sacs or alveolialveoli. It is here . It is here that the oxygen diffuses into the blood. Because they are so that the oxygen diffuses into the blood. Because they are so full of spaces, lungs feel very light and spongy to touch. The full of spaces, lungs feel very light and spongy to touch. The lungs are supplied with air through the windpipe or lungs are supplied with air through the windpipe or tracheatrachea..

A.A. Respiration organs.Respiration organs.B.B. Breathing mechanism.Breathing mechanism.C.C. Internal respiration.Internal respiration.

AIR IS TAKEN DOWN INTO THE LUNGSAIR IS TAKEN DOWN INTO THE LUNGS

Air can enter the body through either the nose or mouth. The nose Air can enter the body through either the nose or mouth. The nose and the mouth are separated by the and the mouth are separated by the palatepalate, so you can breathe , so you can breathe through your nose even when you are eating.through your nose even when you are eating.

Is is better to breathe through your nose, because the structure of the Is is better to breathe through your nose, because the structure of the nose allows the air to become warm, moist, and filtered before it gets nose allows the air to become warm, moist, and filtered before it gets to the lungs. Inside the nose are some thin bones called to the lungs. Inside the nose are some thin bones called turbinal turbinal bones which are covered with a thin layer of cells. Some of these cells bones which are covered with a thin layer of cells. Some of these cells make a liquid containing water and mucus which evaporates into the make a liquid containing water and mucus which evaporates into the air in the nose and moistens it.air in the nose and moistens it.

1. The NOSE and MOUTH1. The NOSE and MOUTH

Other cells have very tiny hair-like projections called Other cells have very tiny hair-like projections called ciliacilia. The . The ciliacilia are always moving, and bacteria or particles of dust get trapped in are always moving, and bacteria or particles of dust get trapped in them and in the mucus. Cilia are found all along the trachea and them and in the mucus. Cilia are found all along the trachea and bronchi, too. They waft the mucus, containing bacteria & dust, up to bronchi, too. They waft the mucus, containing bacteria & dust, up to the back of the throat, so that it doesn’t not the back of the throat, so that it doesn’t not block up the lungsblock up the lungs..

The air then passes into the windpipe or trachea. At the top of the The air then passes into the windpipe or trachea. At the top of the trachea, is a piece of cartilage called trachea, is a piece of cartilage called epiglottisepiglottis. This closes the . This closes the trachea and stops food going down the trachea when you swallow. trachea and stops food going down the trachea when you swallow. This is a reflex action, which happens automatically when a bolus This is a reflex action, which happens automatically when a bolus of food touches the soft palate.of food touches the soft palate.

2. The TRACHEA2. The TRACHEA

The air then passes into the windpipe or trachea. At the top of the The air then passes into the windpipe or trachea. At the top of the trachea, is a piece of cartilage called trachea, is a piece of cartilage called epiglottisepiglottis. This closes the . This closes the trachea and stops food going down the trachea when you swallow. trachea and stops food going down the trachea when you swallow. This is a reflex action, which happens automatically when a bolus This is a reflex action, which happens automatically when a bolus of food touches the soft palate.of food touches the soft palate.

Just below the epiglottis is the voice box or larynx. This contains Just below the epiglottis is the voice box or larynx. This contains the vocal cords. The vocal cords can be tightened by muscles so the vocal cords. The vocal cords can be tightened by muscles so that they make sounds when air passes over them. The trachea that they make sounds when air passes over them. The trachea has rings of cartilage around it, which keep it open.has rings of cartilage around it, which keep it open.

The trachea goes down through the neck and into the The trachea goes down through the neck and into the thoraxthorax. The . The thorax is the upper part of your body from the neck down to the thorax is the upper part of your body from the neck down to the bottom of the ribs and diaphragm. In the thorax, the trachea bottom of the ribs and diaphragm. In the thorax, the trachea divides into two. The two branches are called the right and the left divides into two. The two branches are called the right and the left bronchibronchi. One . One bronchusbronchus goes to each lung and then branches out goes to each lung and then branches out into many smaller tubes called into many smaller tubes called bronchiolesbronchioles..

3. The BRONCHI3. The BRONCHI

At the end of each At the end of each bronchiole are tiny air bronchiole are tiny air sacs or alveoli. This is sacs or alveoli. This is where gaseous where gaseous exchange takes place.exchange takes place.

4. The ALVEOLI4. The ALVEOLI

ALVEOLAR WALLS FROM THE RESPIRATORY SURFACEALVEOLAR WALLS FROM THE RESPIRATORY SURFACE

The walls of the alveoli are respiratory surface. Tiny blood vessels, The walls of the alveoli are respiratory surface. Tiny blood vessels, called capillaries, are closely wrapped around the outside of the called capillaries, are closely wrapped around the outside of the alveoli. Oxygen diffuses across the walls of the alveoli into the blood. alveoli. Oxygen diffuses across the walls of the alveoli into the blood. Carbon dioxide diffuses the other way.Carbon dioxide diffuses the other way.

The walls of the alveoli have several features which make them an The walls of the alveoli have several features which make them an efficient gaseous exchange surface.efficient gaseous exchange surface.

They are very ThinThey are very Thin

Alveolar walls are only one cell thick. The Alveolar walls are only one cell thick. The capillary walls also only one cell thick. An capillary walls also only one cell thick. An oxygen molecule only has to diffuse across oxygen molecule only has to diffuse across this small thickness to get into the blood.this small thickness to get into the blood.

They have an excellent transport systemThey have an excellent transport system

Blood is constantly pumped to the lung along the pulmonary artery. Blood is constantly pumped to the lung along the pulmonary artery. This branches into thousands of capillaries, which take blood to all This branches into thousands of capillaries, which take blood to all parts of the lungs. Carbon dioxide in the blood can diffuse out into parts of the lungs. Carbon dioxide in the blood can diffuse out into the air spaces in the the air spaces in the alveolialveoli, and oxygen can diffuse into the blood. , and oxygen can diffuse into the blood. The blood is then taken back to the heart in the pulmonary vein, The blood is then taken back to the heart in the pulmonary vein, ready to be pumped to the rest of the body.ready to be pumped to the rest of the body.

They have a large surface areaThey have a large surface area

In fact, the surface area is In fact, the surface area is enormousenormous! The total ! The total surface area of all the surface area of all the alveoli in your lungs is over alveoli in your lungs is over 100 m100 m22..

They have a good supply of OThey have a good supply of O22

Your breathing movements Your breathing movements keep your lung well keep your lung well supplied with Oxygen.supplied with Oxygen.

THE RIBS & DIAPHRAGM MOVE DURING BREATHINGTHE RIBS & DIAPHRAGM MOVE DURING BREATHING

To make air move in and out of the lungs, you must keep changing To make air move in and out of the lungs, you must keep changing the volume of your thorax. First, you make it large so that air is the volume of your thorax. First, you make it large so that air is sucked in. then, you make it smaller again so that air is squeezed sucked in. then, you make it smaller again so that air is squeezed out. This is called breathing or out. This is called breathing or ventilationventilation..

There are 2 sets of muscles which help you to breathe. One set is There are 2 sets of muscles which help you to breathe. One set is in between the ribs. This set is called intercostal muscles made up in between the ribs. This set is called intercostal muscles made up of the external and internal intercostal muscles. The other set is in of the external and internal intercostal muscles. The other set is in the diaphragm. The diaphragm is a large sheet of muscle and the diaphragm. The diaphragm is a large sheet of muscle and elastic tissue which stretches across your body, underneath the elastic tissue which stretches across your body, underneath the lung and hearth.lung and hearth.

BREATHING IN IS CALLED BREATHING IN IS CALLED INSPIRATIONINSPIRATION

When breathing in, the muscles of the diaphragm contract. This When breathing in, the muscles of the diaphragm contract. This pulls the diaphragm downwards, which increases the volume in the pulls the diaphragm downwards, which increases the volume in the thorax. At the same time, the external intercostal muscles contact. thorax. At the same time, the external intercostal muscles contact. This pulls the ribs cage upwards and outwards. Together, these This pulls the ribs cage upwards and outwards. Together, these movements increase the volume of the thorax.movements increase the volume of the thorax.

As the volume of the thorax increases, the pressure inside it falls As the volume of the thorax increases, the pressure inside it falls below atmospheric pressure. Extra space has been made and below atmospheric pressure. Extra space has been made and something must come in to fill it up. Air therefore rushes in along something must come in to fill it up. Air therefore rushes in along the trachea and bronchi into the lungs.the trachea and bronchi into the lungs.

BREATHING OUT IS CALLED BREATHING OUT IS CALLED EXPIRATIONEXPIRATION

When breathing out, the muscles of the diaphragm relax. The When breathing out, the muscles of the diaphragm relax. The diaphragm springs back up onto its domed space because it is diaphragm springs back up onto its domed space because it is made of elastic tissue. This decreases the volume in the thorax. made of elastic tissue. This decreases the volume in the thorax. The external intercostal muscles also relax. The rib cage drops The external intercostal muscles also relax. The rib cage drops down again into its normal position. This also decreases the down again into its normal position. This also decreases the volume of the thorax.volume of the thorax.

As the volume of the thorax decreases, the pressure inside it As the volume of the thorax decreases, the pressure inside it increases. Air is squeezed out through the trachea into the nose increases. Air is squeezed out through the trachea into the nose and mouth, and on out of the body.and mouth, and on out of the body.

INTERNAL INTERCOSTAL MUSCLES CAN FORCE AIR OUTINTERNAL INTERCOSTAL MUSCLES CAN FORCE AIR OUT

Usually, you breathe out by relaxing the external intercostal Usually, you breathe out by relaxing the external intercostal muscles and the muscles of the diaphragm. Sometimes, you muscles and the muscles of the diaphragm. Sometimes, you breathe out more forcefully – when coughing, for example. Then breathe out more forcefully – when coughing, for example. Then the internal intercostal muscles contract strongly, making the rib the internal intercostal muscles contract strongly, making the rib cage drop down even further. The muscles of the abdomen walls cage drop down even further. The muscles of the abdomen walls also contract, helping to squeeze extra air out of the thorax.also contract, helping to squeeze extra air out of the thorax.

EXERCISE CAN CREATE AN OXYGEN DEBTEXERCISE CAN CREATE AN OXYGEN DEBT

All the cells in your body need oxygen for respiration All the cells in your body need oxygen for respiration and all of this oxygen is supplied by the lungs. The and all of this oxygen is supplied by the lungs. The oxygen is carried by the blood to every part of the body.oxygen is carried by the blood to every part of the body.

Sometimes, cells may need a lot of oxygen Sometimes, cells may need a lot of oxygen very quickly. Imagine, you are very quickly. Imagine, you are running in a running in a racerace. The muscles in your legs are using up a . The muscles in your legs are using up a lot of energy. To produce this energy, the lot of energy. To produce this energy, the mitochondriamitochondria in the muscles will be in the muscles will be combining combining oxygen with glucoseoxygen with glucose as fast as they can, to as fast as they can, to provide the energy for the muscles.provide the energy for the muscles.

How can that How can that extra energyextra energy be found? be found?

It doesn’t release very much energy, but a little extra might make all It doesn’t release very much energy, but a little extra might make all the difference.the difference.

GlucoseGlucose lactic acidlactic acid + + energyenergy

Extra energy can be produced by anaerobic respiration. Some Extra energy can be produced by anaerobic respiration. Some glucose is broken down glucose is broken down without combining it with oxygenwithout combining it with oxygen : :

A lot of oxygen is needed to A lot of oxygen is needed to workwork as hard as this. as hard as this. You breathe deeper and faster to get You breathe deeper and faster to get more oxygenmore oxygen into your blood. Your heart beats faster to get the into your blood. Your heart beats faster to get the oxygen to the leg muscles as quickly as possible. oxygen to the leg muscles as quickly as possible.

Eventually a limit is reached. The heart and lungs Eventually a limit is reached. The heart and lungs cannot supply oxygen to the muscles any faster. cannot supply oxygen to the muscles any faster. But more energy is still needed for the race.But more energy is still needed for the race.

When you stop running, you will have quite a lot of lactic acid in When you stop running, you will have quite a lot of lactic acid in your muscles and your blood. This lactic acid must be broken your muscles and your blood. This lactic acid must be broken down by combining it with oxygen. So, even though you do not down by combining it with oxygen. So, even though you do not need the energy anymore, you go on breathing hard. You are taking need the energy anymore, you go on breathing hard. You are taking in in extra oxygen to break down the lactic acidextra oxygen to break down the lactic acid..

While your are running, you built up an oxygen debt. You While your are running, you built up an oxygen debt. You ‘‘borrowed’borrowed’ some extra energy without ‘ some extra energy without ‘paying’paying’ for it with oxygen. for it with oxygen.

Now, as the lactic acid is combined with oxygen, you are paying off Now, as the lactic acid is combined with oxygen, you are paying off the debt. Not until all the lactic acid has been used up, does your the debt. Not until all the lactic acid has been used up, does your breathing rate and rate of heart beat return to normal?breathing rate and rate of heart beat return to normal?