Ap Bio Respiration Frq
40) Describe the structure of a mammalian respiratory system. Include in your discussion the mechanisms of inspiration and expiration. In mammals, oxygen first passes through the nasal cavity. The nasal cavity is covered with mucus and cicilia to filter the air. The nasal cavity leads to the pharynx. The pharynx consists of the eustachian tube and the tonsils. The inhaled air then passes to the larynx, trachea, and bronchi. The bronchi lead to the bronchioles in the lungs. In the lungs the pleural membrane facilitates breathing. The bronchioles end in microscopic alveoli lined by a thin, moist epithelium.
The alveoli is the primary site of gas exchange. Branches of the pulmonary arteries send oxygen poor blood to the alveoli; branches of the pulmonary veins transport oxygen rich blood from the alveoli back to the heart. Inspiration (the process of inhaling) begins as the external intercostals and diaphragm contract. When this happens, the lungs expand. After this, negative pressure is used to facilitate respiration. So, air moves from an area of higher pressure, which is the air, to an area of lower pressure in the lungs and aveoli. During inspiration the diaphragm and intercostal muscles contract.
The diaphragm moves downwards, while the intercostal muscles make the rib cage move upwards. These two processes increase the volume of the thoracic cavity and also reduces the air pressure to below atmospheric pressure allowing air to rush into the airways then into the alveoli. With expiration (the process of exhaling) the opposite occurs. Here, the diaphragm and intercostal muscles relax. This allows the diaphragm to move upwards and the intercostal muscles let the rib cage relax to its resting state. This concept is called passive recoil.
After passive recoil occurs, the volume within the thoracic cavity now decreases. This decrease in volume causes an increase in pressure above atmospheric pressure which forces air up and out the airway. In mammals, a large part part of the process of respiration is controlled neurally through the medulla oblongata. The medulla contains the cardiac, respiratory, vomiting and vasomotor centers and deals with autonomic, involuntary functions, such as breathing, heart rate and blood pressure. The main centers in the medula that control respiration are the inspiratory and expiratory center. 3) Discuss the processes of exchange of O2 and CO2 that occur at the alveoli and muscle cells of mammals. Include in your answer a description of the transport of these gasses in the blood. The aveoli is very important to respiration. The aveoli needs to be efficient in obtaining oxygen as the air is approximately 20% oxygen. The aveoli are small, thinly-walled, sacs of air made out of collagen and elastic fibers. It is lined by a thin, moist epithelium, which allows for easy expansion. In respiration, first the lungs are ventilated to maintain their concentration gradient, which draws in fresh air with a higher concentration of O2.
The air then fills the alveoli, which are completely surrounded by many blood capillaries in order to maintain a short diffusion distance for the O2 to diffuse in, and the CO2 to diffuse out, so both bring down the concentration gradients. The blood then carries the Oxygen away, and cycles the CO2 back, maintaining a strong concentration gradient, helping to raise the diffusion rates. It is by this mechanism that mammals are able to maintain respiration in all the cells of their body. The concentration discussed above is crucial to gas exchange because it allows osmosis and diffusion to take place.
To further facilitate diffusion the surface of the aveoli is moist. Eventually, the oxygen diffuses from the capillaries into the interstitial fluid to be taken up by the cells. At the same time, carbon dioxide diffuses from the interstitial fluid into the capillaries. The oxygen can also be stored in myoglobin, which can be found in muscles. Some CO2 will be present in plasma. This lowers the pH of blood. The levels of dissolved oxygen in the blood are usually 100 mm Hg in the lungs, 40 mm Hg in the muscles during rest, and 20 mm Hg in the muscles during exercise.
The oxygen in the aveoli is carried by hemoglobin or in red blood cells. Hemoglobin can be found in red blood cells themselves. The transportation of hemoglobin and oxygen uses cooperation. The cooperation is allosteric. Once oxygen attaches to it, more oxygen molecules attach easily. The opposite occurs when hemoglobin looses one oxygen molecule. The graph of this relationship would be an s-shaped curve. But, both carbon monoxide and oxygen compete to be able to get to the binding site on hemoglobin. Most carbon dioxide is carried as bicarbonate ions (HCO3).
The enzyme carbonic anhydrase speeds up reactions and lets the carbon dioxide dissolve more easily. If the CO2 is not dissolved by an aqueous solution, some of it can be carried by hemoglobin. The hemoglobin carries the CO2 at a different site so it doesn’t compete with the O2. When the CO2 starts out at the alveolus, it first goes to the pulmonary vein, then the left atrium, the left ventricle, the artery, the capillary, and finally the CO2 gets to the muscle cells. If the CO2 travels from the muscles cells to the alveolus, the same process occurs in reverse. 4) Many physiological changes occur during exercise. -Design a controlled experiment to test the hypothesis that an exercise session causes short term increases in the heart rate and breathing rate in humans. -Explain how at least three organ systems are affected by the increased physical activity and discuss interactions among these systems. a. An experiment to test this: First, you would need at least 10 people to participate in the experiment. The bigger the data pool, the more reliable your results will be. You would just need a stopwatch for this experiment.
First, you would measure the heart rate and respiration rate of all the participants. The heart rate would be measured by feeling the pulse of the person by touching their neck. The number of beats felt in one minute is multiplied by 10 to obtain the heart rate. To obtain the respiration rate, simply count the amount of times the person’s chest cavity rises and falls during breathing. This data of the participants at rest would serve as the control. The experimental data would come from the participants during exercise.
So, afterward all the participants would be instructed to run along the some course for about 5 minutes. They would run at a moderate jogging speed. When the 5 minutes are up, the heart rate and breathing would be recorded the same way as before. Then, immediately after the data is recorded, the runners would run for another 15 minutes. The data would be recorded the same way immediately afterward. After the data is recorded, the runners would take a 30 minute rest in order to return to a homeostatic condition. After the rest, the heart rate and respiration rate would be recorded yet again.
If the hypothesis is true, the heart rate and respiration rate should be higher when the participants were exercising. After the rest, the participants should be back to normal. b. – Circulatory System: First of all, the heart in creases the stroke volume (SV). The stroke volume is the volume of blood pumped from one ventricle of the heart with each beat. Then, the body increases the rate of blood circulation to carry oxygen and nutrients to working muscle cells. The increased flow also carries excess CO2 out of the body. So, the cardiac output increases and the blood pressure increases as well.
To cause heat loss during exercise, the capillary beds that go to the skin dilate. – Respiratory System: During exercise there is an increased gas exchange between CO2 and O2. This is needed so a lot more oxygen (O2) can travel to the cells and be used as energy. Also, the increased rate of respiration helps expel the extra CO2 that is produced by the muscle cells. The increased blood circulation during exercise causes the lungs to adapt by recruiting extra capillaries to carry the increased output of the heart, further increasing the quantity of blood in the lung.
This means that the diffusion capacity of the lungs is also affected. – Digestive System: During exercise, the digestive system immediately increases the rate of glycogenolysis. During glycogenolysis there is an increased rate of digestion in the body to break down the carbohydrates into glucose. Cellular respiration uses the glucose to increase the production of ATP. The digestive system also diverts blood away from splanchnic renal areas, where it is not needed much. All these processes help provide fuel and energy for physical activity.