H5+Transport+System+HD

= =

The Transport System:

H.5.7 Outline the transport functions of the lymphatic system.
=Gas Exchange=

Oxygen dissociation curves show the percentage saturation of hemoglobin and /or myoglobin (with oxygen) at each partial pressure of oxygen. Myoglobin is a protein consisting of one globin and one heme group that is used to store oxygen in muscles. Hemoglobin has four heme groups, each attached to different globins that interact with each other. The curve for myoglobin is to the left of the curve for hemoglobin. This is because myoglobin has a higher affinity for oxygen. At moderate partial pressures of oxygen, adult hemoglobin releases oxygen and myoglobin binds it. (Myoglobin only releases its oxygen when the partial pressure of oxygen in the muscle is very low.) The release of oxygen from myoglobin delays the onset of anaerobic respiration in muscles during exercise. The curves also have different shapes. The curve for hemoglobin is S-shaped, whereas the one for myoglobin is not. This is because as oxygen molecules dissociate from hemoglobin, conformational changes occur, making it easier for other oxygen molecules to dissociate. Therefore, blood containing adult hemoglobin releases large amounts of oxygen over a narrow range of oxygen partial pressures (seen on graph). Mother and fetus have different circulatory systems. Fetus must be capable of taking oxygen from the hemoglobin from mother's placenta. Adult hemoglobin is structurally different from fetal hemoglobin. Fetal hemoglobin has a higher affinity for oxygen. Therefore any oxygen released by the mother will bond with the fetal hemoglobin and transported to the fetus. Graph shows that at lower partial pressures, fetal hemoglobin has capability to be more saturated than adult hemoglobin.
 * H.6.1 Define partial pressure**
 * H.6.2 Explain the oxygen dissociation curves of adult and fetal hemoglobin and myglobin.**


 * H.6.3 Describe how carbon dioxide is carried by the blood, including the action of carbonic anhydrase, the chloride shift and buffering by plasma proteins.**

Bohr Effectt: →Blood pH is directly related to the CO2 concentration in the blood. When the concentration of CO2 in the blood increases, this causes the pH in the blood to decrease (become more acidic). As a consequence, oxygen is released from the hemoglobin in the red blood cells. Or, as represented in the graph, this means that the original line shifted to the right, therefore causing a reduction in the saturation of hemoglobin.
 * H.6.4 Explain the role of the Bohr shift in the supply of oxygen to respiring tissues.**



When more energy is needed for the cells, cellular respiration is increased, so the level of CO2 concentration goes up. This decreases the saturation of hemoglobin and decreases the release of oxygen to the cells.

[|How pH Affects Oxy-Hemoglobin Dissociation] After choosing the right tutorial, click on the blue words to proceed

During exercise, more energy is needed therefore the body needs more oxygen to undergo cellular respiration, creating carbon dioxide along with ATP (useable energy). There are two ways the body knows when to undergo cellular respiration when carbon dioxide levels is too high. Since carbon dioxide is transported by the blood plasma as HCO3 the pH of the blood will be lowered by large armounts of carbon dioxide. 1) Chemosensors found in the aorta and carotid arteries will detect exchange and send impluses to the breathing center in the brain (medulla and pons). This center compares the incoming information with the desired value (the set point) and if the blood pH is too low, impulses will be sent to the intercostal muscles and the diaphragm to increase the rate and depth of lung ventilation. 2) The second way the body detects the level of CO2 is too high is in the brain itself. When the medulla's control center registers a slight drop in pH (increase in CO2 level) of te cerebrospinal fluid, it increases the depth and rate of breathing, and the excess of CO2 is eliminated. This entire system is under involuntary control although some voluntary control is possible. In addition the body also knows to undergo more cellular respiration when oxygen levels are too low. That can be detected through sensors in the aorta and carotid arteries in the neck both of which send alarm signals to the breathing contol centers in the brain.
 * H.6.5 Explain how and why ventilation rate varies with exercise.**


 * H.6.6 Outline the possible causes of lung cancer and asthma and their effects on the gas exchange system

Lung cancer** Causes - Smoking American Cancer Society estimates that smoking is responsible for 83% of all lung cancer deaths Secondhand smoke both increases the risk for smoking and the risk for lung cancer - Other chemicals present in the environment, like radon gas and other carcinogens - Personal family history - Diet: Some foods have been found to prevent lung cancer (carrots, sweet potatoes)

Effects: persistent coughing + coughing up mucous and blood + recurring pneumonia
 * 1) Smoke irritates the air passages à causes them to produce more mucus
 * 2) Cilia are temporarily paralyzed and do not transport mucous to throat
 * 3) Leads to coughing à further irritates air passages
 * 4) System of cleaning the air passages fails à pathogens have a better chance of establishing themselves
 * 5) Particles remaining it he lungs may contain carcinogens à leads to lung cancer

Causes of Asthma
 * Asthma**
 * Asthma is hereditary
 * Can be caused by smoking
 * Environmental factors à The risk of develoing asthma is increased by the environment. Recent studies have shown that living in very clean homes makes one more prone to developing asthma. This is beause the immune system is depried of pathogens to fight, and thus reacts against harmless substances. This reaction causes allergies to develop.
 * It is an allergic reaction. Asthma attacks are triggered by allergens such as house dust mites, pollen, pets and some fungi.

Effects of Asthma Asthma attacks:
 * Membrane inside bronchiol tube releases mucous and becomes inflamed.
 * This inflammation causes muscles in the wall of the bronchi contract excessively and cause muscle spasms.
 * Bronchi is narrowed
 * Constriction of bronchial tubes makes it difficult for ventilation to occur.
 * Gas exchange is reduced
 * Leads to wheezing, coughing, and respiratory distress

javascript:; //Mountain sickness may occur when a person travels quickly from a low to a high altitude. Over a period of time the person becomes acclimatized: red blood cell production and ventilation rate increase. People living permanently at high altitude have greater lung surface area and larger vital capacity than those living at sea level.//
 * H.6.7 Explain the problem of gas exchange at high altitudes and the way the body acclimatizes**

-High altitude -Lower air pressure -Reduced air density →air molecules are spread further apart -Atmospheric and partial pressure of oxygen are therefore less than at sea level -Less oxygen inhaled →less oxygen molecules passing through alveolar membranes -Concentration Gradient between O2 and Co2 decreases -Insufficient oxygen causes an increase in pulmonary ventilation -Decreased saturation of hemoglobin by oxygen -Tissues are inadequately supplied with oxygen

These physiological problems of gas exchange at high altitudes are what cause mountain sickness, hypoxia, and alkaleamia. -Mountain sickness is when an onset of fatigue, nausea, breathlessness and headaches occurs through too rapid/deep breathing. -Alkaleamia is when a person loses too much carbon dioxide through rapid/deep breathing that their blood pH becomes dangerously more alkaline. As a result, the body responds by urinating bicarbonate ion (or alkaline urine). This is caused by a decrease in the dissociation of carbonic acid into bicarbonate ion and hydrogen ions as CO2 is exhaled faster than normal. -Hypoxia is caused by the inadequate supply of oxygen to body tissues, causing pulmonary and cerebral edema.

However, the body is able to cope by acclimatizing itself to the environment of the mountain at that specific elevation. The body does so by increasing the rate of ventilation. Since ventilation increases the bone marrow creates more red blood cells to increase the hemoglobin content in the blood. With more hemoglobin available and more over all oxygen entering the body the transport of oxygen increases greatly and cells are supplied with sufficient amounts of oxygen. People that are native to high altitudes often develop physical adaptations such as high lung capacity and greater surface area for gas exchange than those who live at sea level.