BIOS 255 Week 7 Lab

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BIOS 255 – Unit 7 Lab Instructions BIOS 255 Unit 7 Lab Instructions Activity Description Points Part 1 Pulmonary ventilation 7.5 Part 2 Pulse oximetry 5 Part 3 Oxygen dissociation curve 17.5 Total 30 *All due dates can be found on your Canvas calendar or the Modules section. References Saladin, K. (2019). Anatomy and Physiology: The Unity of Form and Function (9 th ed.). McGraw-Hill PART 1: Pulmonary ventilation RESPIRATORY VOLUMES -- Background, Key Terms, and Computations The respiratory system functions in concert with the cardiovascular system in delivering oxygen to the tissues which are removing carbon dioxide and other volatile waste products from the tissues. We measure a variety of physiological parameters to assess respiratory efficiency. Today we are going to measure the air volumes that are associated with the respiratory system and its efficiency of operation. The following terms are important to know. TERM DEFINITION INSPIRATION Breathing air into our lungs, reducing the air pressure in the chest by expanding the thoracic walls and contracting the diaphragm EXPIRATION Moving air out of our lungs, increasing the air pressure in the chest by either relaxing the muscles of inspiration or by forceful exhalation using Valsalva’s maneuver. TIDAL VOLUME (TV) Tidal volume is the lung volume representing the normal volume of air displaced between normal inspiration and expiration when extra effort is not applied, in other words, it is the air volume in one breath that we breathe while asleep or quietly sitting during class. Typical values for adults are between 0.5 – 0.7 Liters. INSPIRATORY RESERVE VOLUME (IRV) The maximal amount of additional air that can be drawn into the lungs by determined effort after normal inspiration. In women it averages 1.9 L, while in men the IRV is 3.3 Liters. EXPIRATORY RESERVE VOLUME (ERV) The maximal amount of air that can be forced from the lungs by determined effort after normal expiration. In women it is about 0.7 L, while in men it is about 1.1 L. RESIDUAL VOLUME The volume in the lungs that cannot be expelled during all conditions except during pneumothorax. This volume is usually between 1.1 – 1.2 Liters and represents the volume of the lungs (dead space). VITAL CAPACITY The average vital capacity in women is about 3.1 L, while in men it is 4.8 L. IRV+ TV+ERV TOTAL LUNG CAPACITY Total lung capacity is larger in men (6.0 L) in comparison to women (4.2 L). . IRV+ TV+ERV+ RV FUNCTIONAL RESIDUAL CAPACITY FRC in women is about 1.8 L, while in men it is about 2.2 L. RV+ERV INSPIRATORY CAPACITY This is measured in terms of the amount of air that can be inhaled following a normal expiration (In other words it is IRV+TV ). In women, it averages 2.4 L, while in men the IRV is 3.8 Liters

BIOS 255 – Unit 7 Lab Instructions TABLE 1.0: MEASUREMENTS Subject 1 Subject 2 TV 0.5 L 0.5 L ERV 1.1 L 0.7 L RV 1.1 L 1.2 L VC 4.8 L 3.1 L 1. With the given volumes what can you tell about subject 1 in terms of their height, the altitude of the place where they live, and fitness level when compared to subject 2? (2.5 points) Both subjects 1 and 2 have almost the same basic breathing pattern and overall lung capacity, as shown by comparing their TV and VC. But subject 1 exhibited higher ERV and RV which can be from factors such as living at a higher altitude or having a higher fitness level. These differences might bring an increase in expiratory capacity or adaptation to environmental conditions. 2. How will these volumes be affected in patients with COPD? (2.5 points) The TV may be unchanged or decreased slightly, the ERV would decrease in COPD because of the difficulty in exhaling air and the VC will decrease due to decreased ERV.

BIOS 255 – Unit 7 Lab Instructions 3. Given the above values calculate the total lung capacity, functional residual capacity, and inspiratory capacity for subjects 1 and 2. (2.5 points) Total lung capacity= VC + RV Functional Residual capacity=ERV+RV 4.8L +1.1L=5.9L 1.1+1.1=2.2L Subject 2 Inspiratory Capacity= TV+IRV: 0.5L+0.75L=1.25L Total lung capacity=VC + RV:3.1L+1.2L=4.3L Functional Residual Capacity=ERV+RV:0.7L+1.2L=1.9L Inspiratory capacity=TV+IRV: 0.5L+0.75L=1.25L PART 2: PULSE OXIMETRY Pulse oximetry is a non-invasive means of measuring the oxygen saturation of arterial blood. Oxygen saturation is defined as the amount of hemoglobin that is bound to O 2 divided by the amount of total hemoglobin that is available to bind with O 2 . Pulse oximetry has become widely accepted as a means of measuring O 2 saturation. It uses two wavelengths of light to measure the saturation of oxygen. The lights shine through the vascular bed and measure the saturation via a probe. Probe placements include the thumb, finger, bridge of nose, ear, and for children the foot and hand. No calibration is required for the equipment. Pulse oximeters have been helpful in reducing the number of arterial blood gases (ABG’s) tests. They are also very useful in assessing trends and/or rapid changes in oxygen saturations. The drawback of this technique is that it measures Hb saturation which can be due to oxygen or binding to carbon monoxide. 1. What is being measured with pulse oximetry? (2 points) Oxygen saturation of arterial blood is measured with pulse oximetry. 2. What is the methodology that allows us to do noninvasive oxygen measurements? (0.5 points) Pulse oximetry detects changes in oxygen levels by clipping a probe like device on part of the body such as the finger or ear lobe; the probe then uses specific light wavelength to measure how much oxygen is in the blood. 3. Can a pulse oximeter help us identify carbon monoxide poisoning in a patient? Explain (2.5 points) No, it can’t be due to its readings that indicate normal oxygen saturation levels, which can be misleading, therefore, other methods should be used. PART 3: Oxyhemoglobin Dissociation Curve 98.5% of oxygen is transported in the blood bound to Hb and 1.5% is dissolved in plasma. Hemoglobin is found in very high numbers within red blood cells, and there are trillions of red blood cells in our blood. Each Hb molecule can carry up to 4 oxygen molecules at 100% saturation. Oxygen

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BIOS 255 – Unit 7 Lab Instructions saturation and partial pressure of oxygen are two different things. Oxyhemoglobin Dissociation Curve Hemoglobin saturation is important because it describes how much oxygen is ‘bound’ inside red blood cells. This saturation level is dependent on the amount of oxygen dissolved in the blood plasma because the dissolved and bound oxygen is in chemical equilibrium. The amount of dissolved oxygen is indirectly measured as the partial pressure of oxygen in plasma (P O 2 ) and expressed as mm Hg. At alveolar- capillary junction the PO 2 increases, and saturation typically increases as well. The opposite is true for peripheral tissue where the partial pressure for oxygen is low and it enhances the dissociation of oxygen from Hb. This relationship is illustrated by the oxyhemoglobin dissociation curve, as shown below. The binding of oxygen to hemoglobin is affected by several factors. These are reflected in the image below as a right (increased dissociation) or left (decreased dissociation) shift of the oxygen dissociation curve. Factors affecting the oxygen dissociation curve include blood pH (acidosis vs alkalosis), carbon dioxide concentrations (hypo vs hyperventilation), temperature (at rest vs exercise or fever), amount of glycolysis by product 2,3-Diphosphoglycerate (DPG).

BIOS 255 – Unit 7 Lab Instructions Some of the clinical conditions like respiratory acidosis and fever will increase in dissociation of oxygen from Hb molecules. The body will also try to compensate for the reduced amount of oxygen availability by increasing the cardiac output. Recall cardiac output is heart rate x stroke volume. While carbon monoxide poisoning, and alkalosis decrease the dissociation. Patel S, Jose A, Mohiuddin SS. Physiology, Oxygen Transport And Carbon Dioxide Dissociation Curve. [Updated 2022 Mar 26]. https://www.ncbi.nlm.nih.gov/books/NBK539815/ A) Alveolar capillaries: (6 points- 2 each) • Where in the body are alveolar capillaries located? In the lungs surrounding the alveoli . • Would hemoglobin be loading or unloading oxygen in these capillaries? It would be loading. • Using the figure above, what is the saturation (%) of blood at the alveolar capillary in a normal person? 98% to 99% B)Systemic capillaries (6 points- 2 each) • Where might you find the distal end of a metabolically active (working) capillary?

BIOS 255 – Unit 7 Lab Instructions This can be found in tissues having a high metabolism. • Would hemoglobin be loading or unloading in these capillaries? It would be unloading. • What is the saturation (%) at this type of capillary? 75% Saturation . C) Loss of blood in the fetus have more detrimental effects than in adults. Knowing fetal Hb has two alpha proteins and two gamma chains instead of two beta chains as found in adult Hb molecules. The gamma chains have a lower affinity for DPG. How do you think this will affect the oxygen dissociation curve? (3 points) The association curve will shift to the left, which will help take oxygen to the placenta to bring efficient oxygen transfer from the mother’s blood to the baby’s blood. This can also allow the baby to obtain oxygen at lower oxygen pressures for proper oxygenation needed for development. D) Do you expect a change in the heart rate greater during alkalosis or acidosis? Why? (2.5 points) The heart during alkalosis will be greater because alkalosis brings a decrease in extracellular hydrogen ions, which gives greater binding of hemoglobin.

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BIOS 255 Week 7 Lab

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