Pathophysiology BMS 243 The Respiratory System Introduction Dr. Aya M. Serry 2015/2016

 The Respiratory System is what controls breathing. It brings in the oxygen to your body, and gets rid of the carbon dioxide that is left over. If you don’t breathe, you would die  When the human body breathes air, it gets sucked through the nostrils or the mouth. Then it goes through the trachea  The trachea divides into tubes called bronchi which carry the air on to each lung

 The respiratory system consists of a series of tubes that transfer air from outside the body to the small air sacs (the alveoli ) in the lungs where gas exchange take place

At the end of the smallest bronchioles are the alveoli There are millions of alveoli in each lung Alveoli are surrounded by a network of small blood vessels called capillaries The Alveoli

Alveoli and adjacent capillaries terminal bronchiole alveoli capillaries

Why do we need to breathe?  Breathing gets oxygen into the body so that cells can make energy  Cells use this energy to contract muscles and power the thousands of biochemical reactions that take place in the cell every second  Without oxygen, cells can’t make energy and without energy, cells would die  The supply of blood and oxygen to cells and tissues is called PERFUSION

 Inside the cells most energy is made by the mitochondria. This energy is in the form of ATP *  In the process of energy production………  Oxygen is consumed by the cells  Carbon dioxide is produced as a waste gas Energy production *Adenosine Triphosphate  Glucose fuels the process

 Oxygen (O 2 ) from the air in the lungs diffuses into the blood  Then It is transported through the Blood to the cells  Then, Oxygen diffuses from the blood into the cells How do cells get their oxygen?

 Carbon dioxide (CO2) from the cells diffuses into the blood  Then It is transported through the blood to the lungs  Then, In the lungs carbon dioxide diffuses into the air and is breathed out How do cells get rid of their carbon dioxide?

Exchange of O 2 and CO 2 between lungs and cells

Oxygen diffuses from the alveoli to the blood in the capillaries While Carbon dioxide diffuses from the blood in the capillaries to the alveoli Gas exchange in the alveoli

 Diffusion is a process that occurs when there is a difference in the concentration of a substance between two areas  The substance, for example oxygen, will diffuse from an area of high concentration to an area of low concentration  No energy is required from the body for this process What is diffusion?

It is the changes in pressure that cause air to enter and leave the lungs Breathing air in and out of the lungs As the ribs rise and fall and the diaphragm domes and flattens, the volume and pressure in the lungs changes Ventilation (breathing)

 Inhalation is the process of taking air into the lungs. For this to occur, the air pressure inside the lungs must be lower than that of the external atmosphere as air flows from areas of higher pressure to lower pressure.  This is achieved by the contraction of the external intercostal muscles which acts to pull the ribcage upwards and outwards, hence, increasing the volume of the thoracic cavity.  The diaphragm also contracts to extend the cavity further downwards. Inhalation

 The size of the lungs: is increased which, in turn, creates an area of lower air pressure inside the lungs; hence, air is drawn into the lungs. Inhalation

 Exhalation is the process of expelling air out of the lungs.  For this to occur, the air pressure inside the lungs must be higher than that of the external atmosphere as air flows from areas of higher pressure to ones of lower pressure.  This is achieved by the relaxation of the external intercostal muscles which bring the rib cage inwards. Exhalation

 This, decreasing the volume of the thoracic cavity and that of the lungs which, in turn, creates high pressure in the lungs; hence air is pushed out of lungs. Exhalation

Inspiration (breathing in) Ribs rise and diaphragm flattens Volume increases and pressure decreases Air enters the lungs Expiration (breathing out) Ribs fall and diaphragm domes Volume decreases and pressure increases Air leaves the lungs Ventilation (breathing)

As we exercise, the body needs to obtain more oxygen and remove more carbon dioxide (CO 2 ) This is done by increasing the rate and depth of breathing An increase in carbon dioxide in the blood is the main trigger that increases the rate and depth of breathing HOW?? Control of Ventilation

Chemoreceptors in the respiratory centre in the brain stem detect an increase in blood CO 2 levels The intercostal and phrenic nerves increase the rate and depth of breathing Additional chemoreceptors on arteries near the heart monitor oxygen and Carbon dioxide levels Control of Ventilation

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