Lab exercise 1. Safety equipment and some basic measurements You should be familiar with the location and use of the safety equipment located in the lab. Your lab instructor will review the location and use of this equipment with you. Safety shower. Located in the back right corner of the lab it consists of a large shower head and a pull handle. The safety shower is used in case of large spills of corrosive, irritating or radioactive material on your person. To use the safety shower pull the handle, stand under the shower and undress. Modesty will not replace skin damaged by chemical burns. Fortunately we will not be using anything in this course that will necessitate the use of the safety shower but you should still be aware of its use and function. There is not a drain under most safety showers. If you play with it and cause a mess you will have to clean it up. Eye wash station. Located in the back left corner of the lab on the corner of the sink it consists of two small shower heads directed upward and a on/off lever. The eye wash station is used in the event of a chemical splash entering the eye. To use the eye wash station hold your head so that your eyes are directly over the shower heads and push the lever down. The covers over the shower head will pop off and the resulting rush of water will rinse your eyes and face. Your eyes have to be open to achieve the maximum benefit. Again this is not something we are likely to need but you should be aware of its location and use. Fire extinguisher. The fire extinguisher is located on the left hand side of the entry door. In case of fire pull the pin from the handle of the extinguisher and squeeze the handles together. Use the hose and nozzle to direct the spray from the extinguisher towards the base of the fire. First aid kit. This is located in the back left corner of the room near the eye wash station. This kit contains basic first aid supplies. You should notify your TA before using material from the first aid kit. Emergency phone. There is a campus phone located just inside and to the left of the door into the prep room. This is located about midway on the left wall of the lab. This phone is only for emergency use. MSDS notebook. This is located in the prep room in the cabinet above the sink. This is a notebook that contains material safety data sheets (MSDS) for all of the chemicals stored and used in the lab. These sheets contain information about the hazards associated with each chemical and information associated with storage and disposal. This resource is important for rescue workers in case of a fire or major chemical spill. You should know the location of the MSDS notebook in any lab in which you work. Take some time to examine these safety devices and make sure you know how to operate them. It could help you to prevent serious harm to yourself or someone else in case of an accident. Basic measurements. Throughout this course we will be taking samples and measurements of physiological parameters. Some of these measurements and sample taking techniques take a few minutes to learn so we will practice a few in this lab to make things more efficient later. You may work in pairs for the following activities. Activity one …pH of urine Collection of urine sample. One individual in each group should obtain a sample of their own urine to test. Sample cups will be available on the side benches. Bathrooms are located in the main hall to the left of the lab door and in the stairwells (female to left, males right) at either end of F corridor (the hall at the end of B corridor to the right of the lab.) Bring the urine sample back to the lab for measurement. You do not need to fill the cup for this measurement. You can obtain a measurement even with a few drops. We will be using urine samples several times this semester so you might as well get used to it at the start. For those of you in the evening sections the double doors at the end of B corridor automatically lock at 6:00. Use the bathrooms in the stairwells. If you use the bathrooms in the hall you cannot reenter B corridor and get to the lab. Do not block these doors open as it will send an alarm to security. Also be careful that you exit at the end of lab. Always use the door on the left of these double doors. If you use the door on the right in will likely not shut properly and cause an alarm. Remember urine should be considered as a biohazard. You should only use your own body fluids and wear gloves. pH measurement. To measure the pH of the samples insert a small strip of the pH paper into the sample. Make sure that the end of the paper strip is moist with the sample. Compare the color of the paper with the standards located on the side of the box of paper strip. You should record the pH to 0.5 of a pH point. If the color matches one of the standards exactly then record as that pH with .0. For example if the color matches the pH 7 standard then your measurement is 7.0. If the color of your sample ph is between two standards then your sample is the lower number +.5. For example if the color is between the standard for 6 and 7 your sample is 6.5. Make sure you do not contaminate the box by touching it with the pH paper that has been in contact with the sample. If you do touch the box with the sample immediately wipe the box with disinfectant. Waste disposal. Make sure to dispose of the waste from this activity appropriately. All urine contaminated items such as used pH paper strips, paper towels, gloves and empty specimen cups should into the large lined biohazard box at the back of the room. . The urine should be poured down the sink with lots of water. Nothing from this lab should go into the “sharps” box. Activity 2…measurement of blood pressure and pulse rate You should have a lab partner measure your blood pressure and pulse rate. Each student should measure a pulse rate and blood pressure and have their pulse rate and blood pressure measured. Measurement of pulse rate. You can measure the pulse rate (heart rate) easily by placing your index and middle finger over any area where an artery lies just under the skin. You can feel pulsations of the artery that correspond with the beats of the heart. These areas where the arteries are relatively superficial are called pulse points. You have pulse points in the neck (carotid artery), wrist on the thumb side (radial artery), middle of the inside of your elbow (brachial artery), in the armpit or axilla ( axillary artery), in the groin or inguinal region (femoral artery), behind the middle of the knee (popliteal artery), inside of the ankle just below the big bump (medial malleous of tibia) (posterior tibial artery) and side of the head just in front of the ear (superficial temporal artery). You should try to find all of these pulse points on yourself or your lab partner (ok you can check your femoral pulse later if you wish). The pulse points typically used for measuring pulse rate are the carotid pulse (neck) and the radial pulse (wrist). To measure a pulse simply count the number of pulsation for 15 seconds and multiply by 4 to obtain beats per minute. Do not use your thumb to measure someone’s pulse rate. There is a small artery in the thumb that could interfere with the measurement. The arteries in your fingers are on the sides of your fingers and not on the tips so they do not interfere with measurement of pulse. Record your carotid pulse and radial pulse. Measurement of blood pressure. We can use one of the pulse points to measure the pressure in the artery at different parts of the cardiac cycle. We will discuss this in more detail later but basically when the heart is relaxing and filling with blood the arterial pressure drops. This low pressure is called the diastolic pressure. When the heart is contracting and expelling blood the arterial pressure rapidly increases. This higher pressure is called the systolic pressure. When we measure arterial blood pressure we measure both values and record it as systolic/diastolic. To measure the blood pressure we are going to inflate an air filled tube (blood pressure cuff) around an artery. We will be able to measure the pressure inside of this air filled tube. When the pressure in the tube exceeds the pressure in the artery the artery collapses and no blood can flow through. If we listen to the artery with a stethoscope we will not be able to hear anything. As we reduce pressure in the cuff blood will be able to force its way through the artery when the arterial pressure equals or is greater than the pressure in the cuff. If we pump up the cuff and then slowly release pressure from the cuff and listen to the artery. At first we will hear nothing (no blood flow) then a period of clicking or tapping noises called the sounds of Korotkoff begin as the artery opens with the systolic pressure and closes as the arterial pressure drops below the pressure in the cuff and the artery closes. When the pressure is below the diastolic you will not be able to hear anything. The pressure at the start of the sounds of Korotkoff is the systolic pressure. The pressure at the end of the sounds of Korotkoff is the diastolic pressure. Procedure Clean the earpieces of the stethoscope with an alcohol swab (Did you really want someone else’s ear wax in your ear? Is earwax a potential biohazard?). Alcohol swabs and their packaging may be disposed of in the normal trash. Place the blood pressure cuff around either arm just above the elbow. The tubes of the cuff should be facing toward the patient’s hand. There is an arrow on the edge of the cuff that should be located over the brachial artery. Make sure all of the air is out of the cuff at this point and that the cuff is fitted snug but not tight. You can remove air from the cuff by opening the valve at the base of the squeeze bulb by turning the knob counterclockwise and squeezing the cuff before placing it on your arm. Place the stethoscope over the brachial artery just distal (below) the blood pressure cuff. Close the valve and inflate the cuff by repeatedly squeezing the rubber bulb. If the cuff does not inflate when you squeeze the bulb make sure the valve is closed tightly. Sometimes placing your thumb over the hole at the end of the bulb while you are squeezing it helps. You have to remove your thumb from the hole to allow the bulb to inflate. Inflate the cuff until the pressure gauge reads 160 mmHg. This should block all blood flow through the brachial artery. You should not hear anything through the stethoscope at this time. Do not leave the cuff inflated for more than 1 minute. Open the valve slight and slowly release pressure from the cuff. Listen while you are releasing the pressure. When you first hear the sounds of Korotkoff note the pressure in the cuff. This is your systolic pressure. Continue to slowly release pressure while listening to the artery. When the sound stops note the pressure in the cuff. This is your diastolic pressure. Completely deflate the cuff and remove it from the arm. The most common mistake is to release the pressure from the cuff too fast. You want to just slightly open the valve so that the pressure drop in the cuff is slow and smooth. If you are having trouble hearing any sounds try repositioning the stethoscope slightly. You can also watch the needle on the dial of the pressure gauge. The needle will twitch slightly as it falls between the systolic and diastolic pressures. Data sheet for lab 1 Urine pH Record the pH of your urine and the pH of your lab partners’ urine ______ ________ Compare this with the data from other groups in the lab. ______ _________ ________ ________ ________ ________ What is the range of urine pH in this sample? From this data could you conclude that urine concentration is under homeostatic control? Why or why not? What other measurements could you make to help support your conclusion? Pulse rate Which pulse point was easiest to find? Which was the hardest? What factors will influence the ease of finding the pulse point? Record your radial pulse _________ carotid pulse __________ Compare this to the pulse rate of your classmates. Radial ___________ carotid __________ ___________ __________ ____________ __________ ___________ ___________ ____________ ___________ ____________ ____________ From this sample could you conclude that resting pulse rate is under homeostatic control? Why or why not? What other measurements could you make to help support your conclusion? Are there any physical differences between the individuals in your sample that might help to account for any variation between pulse rates? What are these characteristics? Blood pressure Record your blood pressure __________ and the blood pressure of several of your classmates. ________ __________ ________ ________ ________ ________ Does this sample suggest that blood pressure is under homeostatic control? Why or why not? Are there any physical differences between individuals in your sample that might help to account for any variation in blood pressure. What are these characteristics? What other type of data would be useful in determining if blood pressure is under homeostatic control? Why? What is the technical name for the blood pressure cuff? Be observant. It’s right in front of you.