Lab #2 Scientific Method, Metric System, Directional Terms and Body Cavities

Transcription

1 Page1 Lab #2 Scientific Method, Metric System, Directional Terms and Body Cavities Objectives Understand the purpose of the scientific method and describe the six steps involved List and describe the sections of a scientific laboratory report Name the base units, abbreviations, and prefixes used in the metric system Apply significant figure rules to mathematical calculations Recognize and describe anatomical position Define and learn to properly use directional terms and planes of section Identify major body cavities Identify abdominal quadrants and abdominopelvic regions I. Scientific Method Scientists are interested in understanding how the natural world works. For this purpose, scientists typically follow an orderly sequence of steps called the scientific method. This process allows scientists to make measurements and collect data to solve a problem and discover new information. The scientific method can be broken down into the following six major steps: 1. Observation. Make observations regarding an environment, condition or situation. 2. Gather Information. Gather and analyze information about topics directly related to your observations. 3. Propose a Hypothesis. An hypothesis is an educated guess specifically developed to explain your observations. 4. Test the Hypothesis. Perform an experiment and collect data to test the hypothesis. 5. Present and Analyze Results. Results data can be presented in many formats, including tables, figures, and graphs. 6. Conclusion. Explain whether the data supports or rejects the hypothesis. The scientific method is cyclical, meaning that after a conclusion is reached, new questions are often asked.

2 Page2 II. Scientific Laboratory Report The process of the scientific method is often documented by a scientific lab report containing the following sections: Introduction: The general topics of the experiment are presented. The introduction section of the lab report should answer the following questions: What was/were the topic/s of the laboratory? What was the experimenter trying to study/discover in this laboratory? What was the hypothesis? What is currently known about the topic? Materials and Methods: In this section, the materials that were used in the experiment are presented and the procedures (how the experiment was performed) are described in detail. A person reading the laboratory report should be able to replicate the study exactly using the information provided in this section. Results: In this section, the data is presented as clearly as possible. Usually, this section includes tables, figures, and/or graphs. Discussion: The discussion section of the laboratory report should explain the data from the results section with respect to supporting or refuting the experiment s hypothesis. The discussion should also explain if the data supports what is currently known about the concept that was tested. If it does not, this is the section where you would identify possible errors in the experiment or suggestions for improvement if the experiment was replicated. Conclusion: This section is used to summarize the information that was presented in the laboratory report. The conclusion should provide the reader with a take home message. Conclusions are usually brief, approximately two to three sentences. In a future laboratory exercise, you will have an opportunity to use the scientific method and write a scientific lab report. III. Metric System A. MAKING MEASUREMENTS Scientific experiments usually involve collecting data by making measurements. By convention the metric system is always used for scientific measurements. The table below shows the base units for the metric system. Mass is measured in grams (g), volume in liters (L), linear measurements in meters (m) and time in seconds (s). Prefixes are used to denote larger and

3 Page3 smaller numbers (Table 1). For example, 1 kilometer (km) is 1000 meters (m), and 1 millimeter (mm) is meters (m), or 1/1000 of a meter. Table 1. The Metric system prefixes Giga G 1,000,000,000 Mega M 1,000,000 kilo k 1,000 hecto h 100 deca dk or da 10 Base unit : Gram (g) Meter (m) Liter (L) Second (s) deci d 0.1 centi c 0.01 milli m micro µ 0.000,001 nano n 0.000,000,001 B. Practice measuring using the instruments provided. Record the mass (in grams), volume (in milliliters) and length (in centimeters) of the items provided to you by your instructor, in your lab report. IV. Significant Figures Every measurement has some degree of uncertainty. Significant figures are used as a way to express the degree of uncertainty associated with a particular measurement. A. Significant Figure Rules Many of the quantities that we measure in the lab are often used for some type of mathematical calculation. The accuracy of these mathematical calculations is limited by the accuracy of the original measurements. Follow the rules below for using significant figures: a. All non-zero numbers are significant. Example: 145 has 3 significant figures b. All zeros between non-zero numbers are significant. Example: 1001 has 4 significant figures

4 Page4 c. All zeros to right of the decimal point AND at the end of the number are significant. Example: has 4 significant figures d. All zeros before a non-zero digit are NOT significant they are placeholders only. Example: has 2 significant figures e. Zeros after a non-zero number with no decimal point are NOT significant. Example: 5000 has 1 significant figure f. Exact numbers have an unlimited number of significant digits. Exact numbers are counted numbers or ones that are created by definition. They have no uncertainty. Examples: 10 heart beats, 12 inches in a foot B. Math with Significant Figures a) Addition / Subtraction round off the answer to the same number of decimal places as the lowest in the calculation. Example: = 6.8 (you must round the answer off to 1 decimal place) b) Multiplication / Division round off the answer to the lowest number of significant digits in the calculation. Example: 4.3 x = 11 (you must round off answer to 2 significant figures) C. Rounding Off Rules When rounding to the correct number of significant digits, use the following rules: a) If the digit being rounded is 5 or greater, round up. Example: 4.56 rounds to 4.6 b) If Less than 5, round down. Example: 4.54 rounds to 4.5 D. Mean (Average) A data set is a collection of numbers. Below is an example of a data set containing 3 values: Example: The mean is the average value for a data set. To calculate the mean, add all the numbers together and divide by the number of values in the data set. Example: = 10.3 then 10.3 divided by 3 = 3.4

5 Page5 E. Answer the following questions using the math rules provided and put the answers in your laboratory report. 1. Indicate the number of significant figures in the following numbers: a b c Round the following numbers to 2 significant digits. a. 113 b c Perform the calculation and use the rounding rules to use the correct number of significant figures. a b x c Calculate the mean of the following data set: (12, 14, 13, 12, 17, 10). V. Anatomical Position & Directional Terms A. Introduction The study of any discipline begins with learning the proper terminology. Anatomists and health care personnel must agree to a standardized language in order to communicate accurately. B. Anatomical Position In human anatomy, directional terms assume the subject is in the anatomical position. Note each of the following body positions on Figure 1 depicting a subject in anatomical position. a. Standing upright in front of the observer b. Head level with eyes forward c. Legs straight, feet flat, pointed forward d. Arms at sides, straight, palms facing forward, thumbs to the side e. Right and left refers to subject, not observer C. Directional Terms Words such as up, under, behind and beside have subjective meanings. For precision, directional terms are used to convey specific relationships allowing precise descriptions of location. Review the directional terms in table 2 and use the definitions to fill in the blanks in part IV of the lab. Note that terms in parentheses are used for animals that walk on four legs.

6 Page6 Table 2. Directional Terms. Definitions and Examples. Directional Term Definition Example of Use a. superior / cranial above or toward the head the nose is superior to the mouth, both are cranial b. inferior (caudal) Below or away from the head the chin is inferior to the mouth c. anterior / ventral* closer to the front of the body the sternum is anterior to the heart d. posterior / dorsal* closer to the back of the body the vertebral column is posterior to the heart e. midline an imaginary line down the center of the body dividing it into matching halves the umbilicus is on the midline. f. medial closer to midline of the body the eye is medial to the ear g. lateral farther from the midline of the body the shoulder is lateral to the sternum h. proximal closer to the point of attachment the elbow is proximal to the hand i. distal farther from the point of attachment the fingers are distal to the wrist j. superficial toward the surface of the body the skin is superficial to the rib cage k. deep toward the interior of the body the lungs are deep to the rib cage l. ipsilateral on the same side of the body all injuries were ipsilateral, on the right side m. contralateral on opposite sides of the body n. visceral pertaining to organs (viscera) o. parietal pertaining to cavity linings control of the right hand by the left motor cortex is contralateral the visceral layer of the pericardium is adjacent to the heart the parietal layer of the pericardium is adjacent to the pericardial cavity p. afferent to carry toward afferent neurons carry impulses toward the CNS q. efferent to carry away efferent neurons carry impulses away from the CNS * Note that these are synonymous for bipeds, but have different meanings for quadrupeds. (Caudal : toward or near the tail) VI. Planes of Section A. Introduction It is often necessary to view only a section or slice of the human body or organ. There are four basic cuts that can be made and these are referred to as body planes or planes of section. The view of the object after it has been cut is called a section.

7 Page7 1. Sagittal plane: A cut through the long axis of the body that results in right and left portions. Also referred to as a longitudinal cut, resulting in a longitudinal section. a. midsagittal plane: The cut is midline resulting in two equal halves. b. parasagittal plane: The cut results in unequal right and left portions. 2. Frontal (coronal) plane: A cut through the long axis of the body that results in anterior and posterior portions. 3. Transverse plane: A horizontal cut that divides the body into superior and inferior portions. Also called cross section. 4. Oblique plane: A cut performed an angle between the other planes. Use these terms to help answer the questions in part V of the lab report. B. Banana Dissection Procedure 1. Observe the shape of the banana. Orient the banana so that the stem is pointed upward. Observe how it is bilaterally symmetrical (a mirror image along the midline) similar to a human. 2. Do not peel the banana, face the stem forward and write a face on it to keep track of its orientation. 3. Perform a transverse section of the banana (using the plastic knife) roughly cutting it in half. Draw the resulting shape of the cut end in lab report part II. 4. Cut the bottom half in a midsagittal section. Draw the cut end. 5. Cut the top half in a frontal section. Draw the cut end. 6. Cut one of the remaining pieces in an oblique section. Draw the cut end. You should have four drawings in part II, one for each cut. VII. Body Cavities A. Introduction The body is divided into cavities. The cavities contain tissue coverings called membranes that will be discussed at a later time. The dorsal body cavity contains the cranial cavity and vertebral /spinal cavity /canal that house the brain and spinal cord, respectively. The ventral body cavity is composed of the superior thoracic cavity with the diaphragm at is inferior margin. This cavity contains the lungs, heart, and parts of the esophagus and trachea. Below the thoracic cavity is the abdominopelvic cavity which contains the abdominal and pelvic organs. This cavity is further subdivided into the abdominal and pelvic cavities.

8 Page8 B. Definitions 1. Dorsal Body Cavity: can be subdivided into the cranial and vertebral cavities although they are continuous with each other a. Cranial Cavity: contains the brain within the skull b. Vertebral Cavity: contains the spinal cord within the vertebral column 2. Ventral Body Cavity: is divided into superior and inferior sections by the diaphragm a. Thoracic Cavity: contains the heart and lungs protected by the rib cage i. Pleural Cavity: fluid-filled membrane-enclosed region that contains the lungs ii. Pericardial Cavity: fluid-filled membrane-enclosed region that contains the heart b. Abdominopelvic Cavity: although there are no physical divisions between these sections, it is easier to refer to the abdominal cavity separately from the pelvic cavity i. Abdominal Cavity: inferior to the diaphragm, the area contains the stomach, liver, intestines, and associated organs ii. Pelvic Cavity: region partially enclosed by the pelvic bones containing the reproductive organs, bladder and rectum C. Mapping the Abdominopelvis As you observed from the human torso, the abdominopelvic cavity contains many organs and structures. The abdominopelvic area can be divided into regions by two methods: the quadrant method and the regional method. 1. Quadrant method: divides the abdomen into four parts via two imaginary lines: one down the midline and the other horizontal through the umbilicus A. right upper quadrant (RUQ) B. left upper quadrant (LUQ) C. right lower quadrant (RLQ) D. left lower quadrant (LLQ) 2. Regional method: four imaginary lines in a tic-tac-toe formation separate the abdominopelvis into nine regions A. umbilical region F. left hypochondriac region B. right lumbar regions G. hypogastric (pubic) region C. left lumbar region H. right iliac (inguinal) region D. epigastric region I. left iliac (inguinal) region E. right hypochondriac region

9 Page9 Lab Report #2 Scientific Method, Metric System, Directional Terms & Body Cavities Name: I. Scientific Method Define hypothesis and explain its importance to the scientific method. II. Scientific Laboratory Report Write in the appropriate section of a scientific lab report into which each of the items below would properly fit. The statements are not necessarily in the correct order. See page Make a prediction that increased sugar consumption has a harmful effect on the body s ability to properly respond to insulin. 2. Set up an experiment to compare two populations of lab mice- one population with a high sugar diet and the other with a regular diet 3. Noticing that people with a higher sugar consumption have a greater risk of diabetes 4. Gather current research information about diabetes 5. Create a data table to present data collected 6. The data support the hypothesis that the lab mice consuming a sugar rich diet respond differently to insulin. III. Metric System Measure each of the specimens on display and record your measurements on the lines below (include the units of measurement) IV. Significant Figures 1. A. B. C. 2. A. B. C. 3. A. B. C. 4.

10 Page10 V. Anatomical Position & Directional terms A. Human Skeleton Model - Locate the labels (I-O) to answer the following questions. 1.Which is the most distal point I, J or K? 2.Which is more medial, L or M? 3.N is relative to O. 4.What is the most superior label? B. Cat Skeleton Model - Locate the labels (P-U) to answer the following questions. 1. Which is the most caudal point (closer to the tail)? P or Q? 2. Are R and S contralateral or ipsilateral? 3. T is _proximal / distal (circle one) relative to U. VI. Planes of Section A. Sectioned Models and Specimens Observe each of the structures on display and determine the body plane/section demonstrated. (Note the orientation of the organs within body using the torso models for reference.) B. Banana Dissection Draw each section as the cut end appears. Transverse Midsagittal

11 Page11 Frontal Oblique VII. Body Cavities A. Human Torso Model (with the exposed vertebral column) - Locate each of the cavities defined previously. The cavities have been labeled (A-F). Record the observed labels on the correct line below. pelvic cavity abdominal cavity cranial cavity vertebral cavity pleural cavity pericardial cavity B. Using the letters A-F above, complete these statements (more than one applies to each). a. The dorsal cavity includes b. The thoracic cavity includes c. The ventral cavity includes C. Human Torso Model - Mapping the abdominopelvis 1. On the human torso, observe the quadrant and regional method of dividing the abdominopelvis by placing the transparent grids in the marked locations. Refer to the torso model to help answer the questions below. 2. Using the quadrant method abbreviations, identify the quadrant that contains: a. the majority of the stomach b. the uterus (two answers) c. the majority of the liver 3. Using the regional method, identify the region(s) that contain(s): a. the spleen b. the right hip c. the center region named for the belly button d. upper right portion of the liver