#1 Ebtihal Al-Remawi Afnan Ali Yanal 1 P a g e 1/15
*before we start: if you are watching the video and have no time for some laughs go to minute (5:28 to 7:02) then go to minute (10:14). I will be adding pictures from the internet. I added the most important slides, but not all of them, because they take too much space as you will see, check slides (5,6,10,20). As I didn t add them. Today, we are going to talk about the Respiratory system, and that it deals with O 2, CO 2 and H 2. - O 2 must be available for the cells, as they (the cells) make ATP in the presence of O 2, - O 2 is an electron accepter, so the mitochondria takes the electrons and keeps the respiratory enzyme chain running to make ATP. For example: one glucose in the presence of O 2, makes 36 molecules of ATP. In the absence of O 2, we get only 2 ATP molecules. If the cells are not utilizing O 2 for some reason, this is called Hypoxia. - Hypoxia, by definition is: decreased O 2 utilization by the cells. What are the Potential Causes of Hypoxia (slide 3) inadequate oxygenation of lungs Atmosphere..high altitude decrease respiratory muscle activity..paralysis pulmonary disease obstructive and restrictive inadequate O 2 transport.. anemia, and heart failure inadequate usage *Cyanide poisoning * Septicemia The Tissues: (slide 7) Individual cells must be capable of taking up and utilizing O 2 properly. Hypoxia can therefore result from a fault at any point along this lungs-blood-tissue chain. 2 P a g e
The question is: What are the potential causes of Hypoxia? (why somebody might suffer from Hypoxia?) 1. Unavailability of O 2 (there is no O 2 ), An example: at high altitudes (the mountains). **Example: atmosphere The atmospheric pressure = 760 mmhg Sea level - At sea level, the P atm is 760 mmhg, and 21% of it is O 2. And so, the Partial pressure of O 2 (P o2 ) is: 760 * 21% = 160 mmhg. - The air is a mixture of gases, and in this mixture, each gas behaves as if it is the only gas available in it. *explanation: this is called the partial pressure concept, for example: when I have a membrane and on one side I have a partial pressure of O 2 (P O2 ) equals 100 (region A), and on the other side of the membrane a P O2 that equals 90 mmhg (region B), diffusion occurs from A to B, regardless of the presence or absence of other gases, (so it doesn t matter if partial pressures of other gases are high or low). B 90 mmhg 100mmHg - But the deal is different in our bodies, for example: when we have 140 Na ions outside and 14 on the inside, there is potential for diffusion towards the inside,, A 3 P a g e
When Na diffuses inside, it carries with it the positive charges, so it becomes positively charged on the inside, and it will prevent any other positively charged ion from entering, So, here we can t say that Na behaves like if it was the only one available (it is NOT isolated from other ions) because there is Electrochemical gradient here. While gases do NOT have charges and so there is no electrochemical gradient. 11 km (11.000m) 5.5 km (5500 m) D C B A The atmosphere is 65 km - Pressure = Force / Area And the force here is the weight of the air column. - At B, the weight of the air column is less than the weight of the air column at A and so the pressure is less at B. - As we go up & reach the height of 5.5 km (5500m), pressure decreases to half its value. C: - So, At the height of 5.5 km: a. The pressure will become 380 mmhg, after it was 760 mmhg at sea level. b. P O2 will become 80 mmhg, after it was 160 mmhg at sea level. ** The gases percentages will stay the same (21% O 2, 79% N 2 ). 4 P a g e
D: - At the height of 11 km (11.000m): a. the pressure will become 190 mmhg. b. P O2 will become 40 mmhg. **remember that gases percentages stay the same. *Conclusion: as we go up O 2 decreases. (We go up by 5.5 km, and everything decreases to half until we reach zero). ** BEFOFE talking about the second cause of Hypoxia, we will explain somethings about the Respiratory system. The Respiratory system begins from the nostrils (openings of the nose) and the mouth, then Pharynx, Larynx, Trachea (division no. 0), trachea divides to right and left Main bronchus (Primary/mother bronchus (division no. 1)), the primary bronchus divides into secondary (division no. 2), and secondary divides into tertiary (division no. 3). And it keeps dividing 23 times ( 23 divisions/branches/generations(. and division no. 23 is the end and it is called Alveolus. When O 2 reaches the alveolus, it either: goes back OR crosses the membrane going to the blood. 5 P a g e
** It looks like a tree if we looked at it upside down: the trachea is the stem of the tree, and the leaves are the alveoli. It is called the Bronchial Tree. Basics of the Respiratory System (slide 18) ** The Respiratory Tree Upper respiratory tract is for all intensive purposes a single large conductive tube The lower respiratory tract starts after the larynx and divides again and again and again to eventually get to the smallest regions which form the exchange membranes Trachea Primary bronchi Secondary bronchi Tertiary bronchi Conductive portion... first 16 branches Bronchioles Terminal bronchioles Respiratory bronchioles with start of alveoli outpouches Alveolar ducts with outpouchings of alveoli Exchange portion... last 7 generations 6 P a g e
Respiration is the process by which the body takes in and utilizes oxygen and gets rid of CO 2. (slide 4) Exchange of gases Directionality depends on gradients Pressure difference From atmosphere to blood -And from blood to tissues Three determinants of respiration Respiration depends on three things: the lungs, the cardiovascular system including the blood, and the tissues. - The part of the respiratory system from the larynx and above is called: Upper Respiratory Tract. - the part below the larynx is called: Lower Respiratory Tract. - If someone has cold, it is called upper respiratory tract infection. - If someone has Bronchitis قصثات),(الحهاب it is called lower respiratory tract infection. **Again, we said that the trachea is generation no. Zero. We can see C shaped cartilage (bone like material), so the trachea is a non-collapsible structure, the cartilage supports it. - Up to the first 10 generations, there is some sort of cartilage. 11 and beyond, there is no cartilage, so these small bronchioles are collapsible (easily collapsed), so they might close because they are not supported. - We can divide the bronchial tree to 2 divisions: 1. The first 16 are called the Conducting zone (airways), their function is only to let air pass, and so no exchange occurs. 2. From 17 to 23 are called Respiratory zone (alveoli) (these are like a balloon), there number is from 300-600 million alveoli. 7 P a g e
Basics of the Respiratory System (slide 13) What structural aspects must be considered in the process of respiration? The conducting zone The respiratory zone The structures involved with ventilation *Skeletal & musculature *Pleural membranes *Neural pathways All divided into Upper respiratory tract: Entrance to larynx Lower respiratory tract: Larynx to alveoli (trachea to lungs) Returning to the causes of Hypoxia, **We need the airways to be opened, and if they were narrowed (obstruction), the air can t go in or out, and that causes Hypoxia. 2- Narrowed airways, are the second potential cause of Hypoxia. **These are called: Chronic Obstructive Pulmonary Diseases (COPDs),.(امراض اوسذاد ة) Emphysema. example: Chronic Bronchitis & - How does narrowed airways cause Hypoxia? We know that the resistance (R) is inversely proportional to the 4 th power of the Radius. (R 1/r 4 ), so little narrowing (we call it bracho-constriction) causes huge increase in resistance. *We can call these diseases Increased Airway Resistance. Example: COPD (we mentioned them). 8 P a g e
3-Lung diseases Lungs are supposed to be compatible, imagine that the lung is a balloon that you want to fill with air, this balloon must be compatible (compliant), and it must NOT be stiff or rigid. The problem might not be in the airways, it might be in the lungs, if there is some form of constriction and the balloon (lung) is NOT inflatable للىفخ) (قاتل (it is not compliant, it is stiff and rigid and we can t inflate it), we call these Restrictive Pulmonary Diseases..(ت كىن محاط تأل اف) Example: Pulmonary Fibrosis **Question: if we brought a lung and a balloon, which one is easier to inflate? - Answer: the lung is easier to inflate, and the balloon is 100 times harder to inflate. (a 1 day old newborn s lungs can inflate, but the baby can t inflate a balloon). - With our lungs like this, we don t need to consume too much energy to breathe, because if we did, the oxygen the lung brings will be consumed for breathing, and so no oxygen will be available for the rest of the body. That s why the lung should be compliant meaning that with little force i can change the shape. (if i (مطاوع) put too much force to change the shape it s incompliant). And again if the lung isn t compliant, this is called restriction. - We mentioned a disease called Pulmonary Fibrosis, If someone has this disease, he/she will die in 3 years, as the lung is continuously shrinking, and eventually it will NOT be able to inflate. 9 P a g e
- Normal people spend 2% of our total ATP expenditure for the Respiratory muscles, and 98% for the rest of the body, and some person (with lung disease) might spend 70% just to inflate lung and so he will get fatigue. Tiny summary for what we have mentioned: **Potential causes of Hypoxia: 1. Unavailability of Oxygen. (high altitudes) 2. Increased airway resistance 3. Some sort of restriction (lungs) Now, we are going to talk about the alveoli عىقىد العىة),(محل they are surrounded by capillaries, and each alveolus is surrounded by a huge جخ لىها محل الطاتة ال ( capillaries). network of capillaries (sometimes 1000.(تحكىن تشثكة عشان جشىطها واوث ماش - There is a huge number of capillaries in the lung. - O 2 is present in the alveoli, and it will cross to the blood, we will assume (to simplify things) that the O 2 crosses 3 layers which are: Alveolar epithelium, the Interstitial, and the capillary endothelium, (while actually there are 6 layers). CO 2 will cross from the blood to the alveoli. **we call these layers: Respiratory Membrane. 3 important sentences: 1. Oxygen can cross any membrane as if the membrane doesn t exist. It s like a ghost, since all cells need it, it crosses membranes this way. 10 P a g e
2. CO 2 crosses any membrane 20 times easier than O 2. 3. if this membrane becomes thick, then the O 2 will find difficulty to cross, so there is a limit (physiologically/normally) 4.Thickining of the membrane (4 th cause of Hypoxia) -the problem is in the membrane, it becomes thick, for example if someone has Pneumonia رئى ),(الحهاب Tuberculosis, or if the interstitial كإو ا جثىا اسفىجة وحط ىاها ) Edema became filled with water: True Pulmonary if it was filled with water from the inside we call it: Alveolar,(تالم Edema, and if it was filled from the outside, we call it: Interstitial Edema. (Interstitial edema occurs before alveolar). - The polymer size of the membrane (increases) & the membrane becomes thick. **i m not sure what the doctor said here exactly, and this is the best i came out with. 11 P a g e
- We know that diffusion is directly proportional to the surface area (A) available & inversely proportional to the thickness (the thicker the membrane, the less the diffusion) (diffusion A/thickness) 5.Anemia & heart failure, 5 th cause of Hypoxia. - The blood consists of 2 things: a. 55% plasma : 92% water, 8% others. b. 45% cells: we say that they are RBCs, because: for each WBC there is 1000 RBCs, and RBCs are 5 million while WBCs are 5000. - RBCs have Hemoglobin (Hb) and so they bind to Oxygen, so when O 2 crosses to blood, it binds to Hb and that makes Oxyhemoglobin. - Now, if someone has Anemia (decreased number of RBCs or less Hemoglobin concentration), there will be less O 2 availability. - The blood is going to be ejected by the heart, so the heart failure can NOT eject. (Heart Failure causes Hypoxia). 6. Poisoning, causes Hypoxia. The cells themselves even oxygen is available, they can NOT utilize oxygen. The cell /the mitochondria/ the respiratory chain enzyme are Poisoned, one bill of Cyanide (poison) can block the respiratory enzyme chain, while O 2 is available. The cells.( خحىق) suffocate 12 P a g e
(تسمم الدم).7 Septicemia -Why do we fear it?? Because some Bacteria secrete toxins, that poison the mitochondria and so they prevent it from using O 2. So O 2 is available, but it can NOT use it. ** Tiny summary again: Causes of Hypoxia: 1. Unavailability of oxygen. 2. Increased airway resistance. 3. Incompliant lung. (restriction). 4. Thickening of the membrane. 5. Heart failure 6. Anemia (خلل عل مسحىي الخل ة).7 Cyto-sick level Cyto-toxic Hypoxia (poisoning and septicaemia). Or we call it: histo-toxic (histo means a group of cells). (الشرا ه تسكروا) arteries. 8. Stagnation of the (The arteries are stenosed (narrowed)) 9. Hypoxic Hypoxia: there is a problem outside, or in the lung, but the result is that the oxygen can t get inside the lung. **Breathing is inspiration/inhalation (air going inside the lung) and expiration (air going outside the lung). - Inspiration: is the flow of the air,(جر اوه) and the flow is directly proportional to the Driving Force (DF) and inversely proportional to the Resistance (R). - Flow DF/ R 13 P a g e
Mechanics of Breathing (slide 38) Airflow is governed by the basic flow equation, which relates flow to driving force (pressure) & airways resistance. Always remember Ohm s law: Flow = pressure difference (driving force) / resistance = P/R 1. By positive Pressure Breathing: resuscitator: P at the nose or mouth is made higher than the alveolar pressure (P alv ). This is artificial type of breathing 2. By negative Pressure Breathing: P alv is made less than P atm. This is normal pattern of breathing It is the pressure difference between the two opposite ends of the airways: (P alv P atm ) If R is large then P must be large too to keep flow constant. Boyle s law: The pressure and the volume of a gas are inversely related if the temperature is kept constant. - The DF for air is the pressure difference. - Pressure outside (atmospheric pressure) is 760 mmhg, we consider it as Zero level. And so, 761 is (+1) and 759 is (- 1). - If the pressure outside and inside equal 760 mmhg, this means that there is no pressure difference and so there is no air flow. *P atm = P alveoli, P = zero, no flow from outside to inside. 14 P a g e
***if we want the air to flow to the inside, we have two things to do: 1. We make the P atm (atmospheric pressure) greater than the alveolar pressure (P alv ): this is called positive pressure breathing (+1) 2. Or we make the alveolar pressure less than the atmospheric pressure. (-1) and this one is called negative pressure breathing Ventilation (slide 41) Inspiration Occurs as alveolar pressure drops below atmospheric pressure.. negative pressure breathing For convenience atmospheric pressure = 0 mm Hg A negative value (-) indicates pressure below atmospheric P A positive (+) value indicates pressure above atmospheric P At the start of inspiration (time = 0), atmospheric pressure = alveolar pressure» No net movement of gases! No driving force (Ohm s) At time 0 to 2 seconds Expansion of thoracic cage and corresponding pleural membranes and lung tissue causes alveolar pressure to drop to -1 mm Hg 15 P a g e Air enters the lungs down the partial pressure gradient
There are two types of breathing: 1. Positive pressure breathing: outside pressure is more. 2. Negative pressure breathing: outside pressure is less. Normally, we can t manipulate the outside pressure, and so our normal breathing is negative pressure breathing, and for the positive pressure breathing, we need to use a tube that is connected to a machine, and this machine makes the pressure inside it positive to push the air to the lungs, and makes the pressure negative to pull the air outside the lungs, this machine is called (Respirator). ***Don t forget to check slides (5,6,10,20)*** Which of the following physiological changes are you likely to experience during the first few days at high altitude? A-decreased pulse rate B-increased blood pressure C-increased appetite D-all of the above Which of the following atmospheric changes occur as you climb higher up a tall mountain? A-the air pressure goes down but the percent of the air that is oxygen remains the same. B-both the air pressure and the percent of the air that is oxygen go down. C-the air pressure remains the same but the percent of the air that is oxygen goes down. Keep breathing, this is just the introduction (in French) GOOD LUCK. 16 P a g e