1. The Respiratory System
Pathophysiology
BMS 243
The Respiratory System
Introduction
Dr. Aya M. Serry
2017

2. The Human Respiratory System

3. The Human Respiratory System
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

4. The Human Respiratory System
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

5. Components of the Respiratory System
Conducting Zone.
Respiratory Zone

6. Conducting Zone
All the structures air passes through before reaching the respiratory zone.
Function:
Warms and humidifies inspired air.
Filters and cleans:
Mucus secreted to trap particles in the inspired air.
Mucus moved by cilia to be expectorated.
Insert fig. 16.5

7. Respiratory Zone Region of gas exchange between air and blood.
Includes respiratory bronchioles and alveolar sacs.

8. Bronchi and Lobules of the Lung

9. Respiratory Membrane

10. Respiratory Volumes
Tidal volume (TV) – air that moves into and out of the lungs with each breath AT REST (approximately 500 ml)
Inspiratory reserve volume (IRV) – air that can be inspired forcibly beyond the tidal volume (2100–3200 ml)
Expiratory reserve volume (ERV) – air that can be evacuated from the lungs after a tidal expiration (1000–1200 ml)
Residual volume (RV) – air left in the lungs after maximal forced expiration (1200 ml)

11. Dead Space
The volume of the airways that does not participate in gas exchange
Anatomical dead space – the volume of air which is inhaled that does not take part in the gas exchange because it remains in the conducting airways (150 ml)
Functional dead space – alveoli that fail to act in gas exchange due to collapse or obstruction
Physiological dead space – sum of alveolar (functional) and anatomical dead spaces

12. The Human Respiratory System
The Alveoli
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

13. Alveoli and adjacent capillaries
The Human Respiratory System
terminal bronchiole
alveoli
capillaries
Alveoli and adjacent capillaries

14. Physiology of Respiration
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

15. Physiology of Respiration
Energy production
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
Glucose fuels the process
*Adenosine Triphosphate

16. Physiology of Respiration

17. Physiology of Respiration
How do cells get their oxygen?
Oxygen (O2) 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

18. Physiology of Respiration
How do cells get rid of their carbon dioxide?
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

19. Physiology of Respiration
Exchange of O2 and CO2 between lungs and cells

20. Physiology of Respiration
Gas exchange in the alveoli
Oxygen diffuses from the alveoli to the blood in the capillaries
While Carbon dioxide diffuses from the blood in the capillaries to the alveoli

21. Gas exchange in the alveoli

22. Physiology of Respiration
What is diffusion?
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

23. What is diffusion?

24. Movement of air depends upon
Air movement
Movement of air depends upon
Boyle’s Law
Pressure and volume inverse relationship
Volume depends on movement of diaphragm and ribs

25. Physiology of Respiration
Ventilation (breathing)
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
It is the changes in pressure that cause air to enter and leave the lungs

26. Inspiration
Inspiration
Diaphragm contracts -> increased thoracic volume vertically.
Intercostals contract, expanding rib cage -> increased thoracic volume laterally.
Active
More volume -> lowered pressure -> air in.
(Negative pressure breathing.)

27. Expiration Expiration Due to recoil of elastic lungs. Passive.
Diaphragm domes, ribs fall
Less volume -> pressure within alveoli is above atmospheric pressure -> air leaves lungs.
Note: Residual volume of air is always left behind, so alveoli do not collapse.

28. Inhalation
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.

29. 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. 

30. Exhalation
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.

31. 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.

32. Ventilation (breathing)

33. Physiology of Respiration
Ventilation (breathing)
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

34. Physiology of Respiration
Control of Ventilation
As we exercise, the body needs to obtain more oxygen and remove more carbon dioxide (CO2)
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??

35. Chemoreceptors
Chemoreceptors are located throughout the body (in brain and arteries).
chemoreceptors are more sensitive to changes in PCO2 (as sensed through changes in pH).
Ventilation is adjusted to maintain arterial PC02 of 40 mm Hg.

36. Physiology of Respiration
Control of Ventilation
The intercostal and phrenic nerves increase the rate and depth of breathing

39. Oxygen transport by the Blood
O2 is transported by the blood either,
Combined with haemoglobin (Hb) in the red blood cells (>98%)
Dissolved in the blood plasma (<2%).

40. Oxygen transport by the Blood
- Haemoglobin molecules can transport up to four O2’s
- Co-operative binding: haemoglobin’s affinity for O2 increases as its saturation increases
- When 4 O2’s are bound to haemoglobin, it is 100% saturated, with fewer O2’s it is partially saturated
- Oxygen binding occurs in response to the high PO2 in the lungs

41. Oxygen transport by the Blood

42. Haemoglobin Saturation
Haemoglobin saturation is the amount of oxygen bound by each molecule of haemoglobin
Each molecule of haemoglobin can carry four molecules of O2
When oxygen binds to haemoglobin, it forms: Oxyhemoglobin
Haemoglobin that is not bound to oxygen is referred to as
Deoxyhemoglobin

43. Haemoglobin Saturation
The binding of O2 to haemoglobin depends on:
- the PO2 in the blood and
- the bonding strength or affinity, between haemoglobin and oxygen
The graph on the following page shows an oxygen dissociation curve, which reveals the amount of haemoglobin saturation at different PO2 values
* PO2 is the Oxygen Partial Pressure

44. Oxygen-Hemoglobin Dissociation Curve
In the lungs the partial pressure is approximately 100mm Hg.
At this Partial Pressure haemoglobin has a high affinity to O2 and is 98% saturated.

45. Oxygen-Hemoglobin Dissociation Curve
In the tissues of other organs a typical PO2 is 40 mmHg.
haemoglobin has a lower affinity for O2 and releases some of its O2 to the tissues.
When haemoglobin leaves the tissues it is still 75% saturated

46. Carbondioxide transport by the Blood
Carbon dioxide also relies on the blood for transportation
Once carbon dioxide is released from the cells, it is carried in the blood primarily in three ways:
Dissolved in plasma (5%)
As bicarbonate ions resulting from the dissociation of carbonic acid (90%)
Bound to haemoglobin (Carbaminohemoglobin) (5%)

47. Carbondioxide transport by the Blood
Part of the carbon dioxide (only 5 – 10%) released from the tissues is dissolved in plasma
This dissolved carbon dioxide comes out of solution (Blood) where the PCO2 is low, such as in the lungs
There it diffuses out of the capillaries into the alveoli to be exhaled

48. Hypoxia and Cyanosis
Hypoxia is defined as a deficiency in either the delivery or the utilization of oxygen at the tissue level, which can lead to changes in function, metabolism and even structure of the body
Cyanosis is defined as a bluish discoloration, especially of the skin and mucous membranes, due to excessive concentration of deoxyhemoglobin in the blood
Cyanosis is divided in to two main types: Central (around the core, lips, and tongue) and Peripheral (only the extremities or fingers)

49. THANK YOU…..