Digestive Anatomy Lab System Overview

Transcription

1 Digestive Anatomy Lab System Overview In-Lab Exercises Read Me This is a very diverse lab. We will be looking at the gross anatomy of the urinary tract, the microscopic anatomy on both models and slides, and some basics of urinalysis. Use the wordlists found in this document. The order is not important!

2 Step 1. Study the Urinary System Model #1 Find all of these structures on the model Adrenal gland Kidney Ureter Bladder Urethra Renal capsule Major arteries coming off the Aorta: Celiac, Superior mesenteric, Gonadal, Inferior mesenteric Renal artery Renal vein Hilus/Hilum Renal pelvis Cortex/cortical layer Medulla/medullary layer Calyx (major & minor) Renal pyramid Renal papilla

3 Step 2. Study the Large Kidney Model #1 Find the model pictured, and find the structures on the wordlist in order. Sometimes this model is on a stand, other times it is mounted on a flat board. The model may not look exactly as the one pictured. Read Me Notice a few things: This model depicts a kidney that has been sequentially dissected, showing you the outside of the kidney at the top, then cutting around a pyramid and the calyces in the middle, and cutting through the pyramids and calyces at the bottom. Ureter Renal pelvis (cut through) Hilus - if model is on a stand, turn model around to see un-dissected, with ureter and vessels entering/leaving. Renal capsule Renal cortex/cortical layer Renal medulla/medullary layer Renal pyramid - on lower 2 pyramids, you see a frontal section - on upper 3 pyramids, you see them from the outside - note renal sinuses next to calyces. These would be filled with adipose, etc. Calyx (major & minor) - on lower 2 pyramids, you see a frontal section - on upper 3 pyramids, you see them from the outside - note renal columns between the pyramids Renal papilla - on lower 2 pyramids, you see a frontal section - on upper 3 pyramids, you cant see them as they are surrounded by the calyces - note the papilla pointing at you on the upper-most part of the model. Note there are others scattered around the model Renal artery Renal vein Segmental a. & v. Branching off renals, running through sinus Interlobar a. & v. Running along side pyramid through column - sometimes these are split by authors and images into the lobars and the interlobars. Arcuate a. & v. Running along top of pyramid Interlobular a. & v. Running into cortex Renal corpuscle in cortical layer (lower part of model. These are NOT to scale!)

4 Step 3. Torso or anterior pelvis model #1 This can be done wither on a torso model, with intestines removed, or one of the anterior hip models. Read Me Notice that, usually, the front of one of the kidneys can be removed Adrenal gland Kidney Ureter, following it down to the bladder Urethra (if visible) Renal capsule Major arteries coming off the Aorta: Celiac, Superior mesenteric, Gonadal, Inferior mesenteric Vena cava (inferior) Renal artery Renal vein Hilus/Hilum Renal pelvis Cortex/cortical layer Medulla/medullary layer Calyx (major & minor) Renal pyramid Renal papilla

5 Step 4. PART ONE of the Kidney Nephron - Glomerulus model Read Me Notice that this model comes in 3 parts. Are we move from left to right, we are increasing magnification. Please take a moment to compare the three individual models, identifying how they relate to each other. We will do each part of this model with a separate word list, so different parts can be worked on at the same time. Also, there are different versions of this model. The one seen in the image will be on the exam. #1 The whole kidney Ureter Renal pelvis Hilus Renal capsule Renal cortex/cortical layer Renal medulla/medullary layer Renal pyramid Calyx (major & minor) - on lowest pyramid, you see a frontal section - note the renal sinuses next to calyces. These would be filled with adipose, etc. Renal columns between the pyramids Renal papilla - on lowest pyramids, you see a frontal section - on upper 3 pyramids, you cant see them as they are surrounded by the calyces - note the papilla pointing at you on the lowest-most part of the model. Renal artery Renal vein Segmental a. & v. Branching off renals, running through sinus Interlobar a. & v. Running along side pyramid through column - sometimes these are split by authors and images into the lobars and the interlobars. Arcuate a. & v. Running along top of pyramid Interlobular a. & v. Running into cortex Renal corpuscle in cortical layer (lower part of model. These are NOT to scale!) ID these parts of the nephron, noting their location within the kidney s layers Renal corpuscle. Proximal convoluted tubule Loop of Henle (ID the descending and ascending arms) Collecting duct

6 Step 4. PART TWO of the Kidney Nephron - Glomerulus model #2 The Nephron Read Me Do this! 1 Notice that this model is not to scale the nephron would not be so large, Also notice that in the center, they are showing you the tubular portion with vessels removed. Some of the corpuscles have been cut through, to show you the contents. To the left and right, they are showing you the vascular portion, with the tubes removed. ID the renal capsule, the cortex, the pyramid, the interlobar a. & v., the arcuate a. & v., and the interlobular a. A On the model, ID the corpuscle marked A on the image. 1. Does it make sense to you that you are actually looking at the parietal layer of the glomerular capsule? 2. Can you differentiate between the afferent and efferent arteriole? Which one is attached to the interlobular a.? Look at one of the dissected corpuscles. ID the glomerulus, and the glomerular (Bowman s) capsule. Notice the afferent arteriole coming into the glomerulus, and the efferent arteriole leaving it. Place your finger on one of the dissected corpuscles. Trace your finger along the Proximal convoluted tubule, the descending arm of the Loop of Henle, the ascending arm of the Loop of Henle, the Distal convoluted tubule, all the way to the Collecting duct. Follow the Collecting duct down to the papilla of the pyramid. Notice they have cut off several nephrons along the way down. 5 There are 2 Loops of Henle on the model. One is much longer, with an obvious thin and thick segment on the ascending arm. The long one is called a juxtamedullary nephron, because it goes so far down into the medullary layer. It is specially adapted to help re-absorb ( conserve ) water back into the bloodstream. It would be surrounded by that Vasa Recta (elongated capillary bed) you see on the left of the model. Do you see the arteriole feeding into the Vasa Recta?

7 Step 5. PART THREE of the Kidney Nephron - Glomerulus model #3 Glomerulus and Bowman s Capsule Do this! 1 You are seeing a renal corpuscle that has been cut though to show you the filtration mechanism. At the top of the corpuscle (on this model it doesn t have to be up ), you first see the Distal convoluted tubule. How do you know that is the Distal convoluted tubule? Because, believe it or not, it always wraps back around towards the glomerulus. If you don t believe me, go take a look at the Nephron Glomerulus part of the model we looked at in PART TWO!!! Just below the DCT, you can see the afferent arteriole entering the corpuscle, and the efferent arteriole leaving the corpuscle. How can you know which is which? There s a vessel on the right, and another on the left!!? Because the afferent arteriole has the Juxtaglomerular apparatus, which releases the hormone Renin. NOTE: on the model in image A, it has been cut through to show you the thickened cells. On some models it is not cut through, and just looks like a thickened area on the arteriole. See image B. 2 Now let s look at the filtration system inside the corpuscle. The afferent arteriole is leading into the glomerulus, which is a capillary bed. Normally, it is completely covered by the visceral layer of the Bowman s capsule, so you wouldn t be able to see it. In image A, they removed the visceral layer on the right side of the model, allowing you to see the capillary. On some models, they remove the visceral layer of the Bowman s capsule on the RIGHT side, so you can see the afferent arteriole leading into the glomerulus. In Image C, I am showing you the glomerulus on another model that we sometimes use in the lab. 3 On both versions of the model, where they left the visceral layer intact, we can see the special cells called Podocytes. We can also see the parietal layer of the Bowman s capsule, forming the shell of the corpuscle. So what is that tube at the bottom of the model? That is the Proximal convoluted tubule. At this point, your group may want to do the kidney dissection. This is Step Seven, found in a different file. Or, move to the Urinalysis area.

8 Step 5. Urinalysis PART ONE Visual Inspection and the Chemstrip Read Me Here we are going to look at some common urine tests. We will be testing 5 subjects. We will also discuss what we might find with certain diseases. Don t worry we won t be going in too much detail. Just enough to give you the big picture. There is a data analysis sheet printable with your wordlist. THIS IS FROM YOUR STUDY GUIDE: Some examples of Urine Color, and possible causes: #1 Visual Inspection COLOR: Urine comes in many colors. See 1 st yellow box for some examples (no, you are not responsible for these!). All we will be looking at is different shades of yellow, which usually indicates dehydration. Follow the instructions on the laminated card accompanying the samples. TURBIDITY: This refers to how clear the urine is. See 2 nd yellow box for some examples (no, you are not responsible for these!). Follow the instructions on the laminated card accompanying the samples. RED, ORANGE UTI, hemoglobinuria, kidney stones, Beets, Blackberries, laxatives, many medications BLACK, BROWN Fava beans, some plastics, hemolytic anemia, many medications GREEN Asparagus, black licorice, porphyruria, some medications PURPLE, BLUE Gram negative UTI, porphyria, herbicide ingestion #2 Chemstrip #3 We will also provide instruction for performing a chemical analysis using a urine dipstick. The testing may consist of any or all of the following: ph, protein (as a semi-quantitative analysis), glucose, bilirubin, ketones, hemoglobin (blood), urobilinogen, nitrite, leukocytes (leukocyte esterase) and specific gravity. Know these terms for lecture and lab: Anuria Dysuria Proteinuria Glycosuria Hematuria Pyuria Ketonuria Albuminuria Urinary nitrites Pyelitis Some things that will make urine cloudy/turbid: Heat exposure or dehydration Pregnancy Urinary tract infection Bladder cancer Kidney problems Inflammation or infection of the prostate gland Sexually transmitted diseases Cardiovascular diseases, including hypertension and heart failure Certain autoimmune diseases Diabetes Sickle cell anemia Leukemia Lymphoma

9 INSTRUCTIONS for Visual Inspection of urine During the practical, you will not be tested on your ability to visually examine urine! COLOR: We will just check for hydration levels. Compare the tube to the accompanying chart: TURBIDITY: Cloudiness/turbidity checked by holding sample up in front of typed text. You may use any book you like. SMELL: Yes, we also check smell, which can indicate bacterial infection.

10 INSTRUCTIONS for using the CHEMSTRIP There is a data analysis sheet printable with your wordlist. CAUTION: Careful attention must be paid to time limits set for each reagent pad. Read the instructions on the Test Strip jar! EXAMPLE: A positive reaction (small or greater) at or less than 2 minutes on the leukocyte test may be regarded as a positive indication of leukocytes in urine. Color changes that occur after 2 minutes are of no diagnostic value. ANOTHER CAUTION: while doing the ph test - If proper procedure is not followed and excess urine remains on the strip, a phenomenon known as "run over" may occur in which the acid buffer from the protein reagent area will run onto the ph area, causing a false lowering in the ph result. ANOTHER CAUTION: Urobilinogen - The absence of urobilinogen cannot be determined with this test. For best results, samples should be at room temperature when tested since reactivity is influenced by specimen temperature. Follow these steps: 1. Thoroughly mix urine specimens by inverting the tube 10X. 2. Remove one strip from the vial and replace cap. 3. Hold the strip against vial to observe proper reading format. 4. Completely immerse reagent areas of the strip in the urine specimen and remove immediately. Start the timer and touch (blot) the edge of the strip on an absorbent material to remove the excess urine. This prevents the run-off phenomenon which can lead to erroneous or inaccurate results. 5. Hold the strip in a horizontal position to prevent possible mixing of chemicals from adjacent reagent areas and/or contaminating the hands with urine. 6. Compare reagent areas to corresponding Color Chart on the bottle label at the time specified. HOLD STRIP CLOSE TO COLOR BLOCKS AND MATCH CAREFULLY. Avoid laying the strip directly on the Color Chart as this will result in the urine soiling the chart. 7. After dipping the strip, check the ph area. If the color on the pad is not uniform, read the ph reagent area immediately, comparing the darkest color to the appropriate Color Chart. 8. Refer to specific manufacturer s instructions on package insert or on vial for permitted reading time. A positive reaction (small or greater) at or less than 2 minutes on the leukocyte test may be regarded as a positive indication of leukocytes in urine. Color changes that occur after 2 minutes are of no diagnostic value. 9. Record results on patient chart (Analysis Sheet below). 10. Discard used reagent strip. Reseal specimen & set aside for possible further testing.

11 Step 5. Urinalysis PART TWO The Specific Gravity #1 Using a refractometer to measure specific gravity. Read Me THIS IS FROM YOUR STUDY GUIDE: Specific gravity measures urine density or the ability of the kidney to concentrate or dilute the urine over that a plasma. Specific gravity is directly proportional to urine osmolality, which measure solute concentration. In other words, specific gravity = density sample density pure water By User:Kandschwar (Own work) [CC BY-SA 2.0 de ( via Wikimedia Commons The sample is always denser than pure water, so the number is greater than 1. Specific gravity should be between and on a random sample of urine. Any measurement below this range indicates hydration, and any measurement above indicates dehydration. If specific gravity is below (that is more like pure water), without having ingested any food or water for 12 hours, renal concentrating abilities are impaired, and the patient is losing water in the patient either has generalized renal impairment or diabetes insipidus. Any urine having a specific gravity over is either contaminated (something else has entered their urine, such as dye), or contains very high levels of glucose (glycosuria).

12 Start Here INSTRUCTIONS for using the Refractometer

13 Step 5. Urinalysis PART THREE Microscopic Exam of Urine #1 There is a chart in lab showing common bodies found in a urine specimen. Read Me THIS IS FROM YOUR STUDY GUIDE: Red Blood Cells Hematuria is the presence of abnormal numbers of red cells in urine due to: Urinary tract infections (UTI), glomerular damage, kidney trauma, urinary tract stones, etc. This will be confirmed with the urinalysis sticks. White Blood Cells Casts Pyuria (pus in urine) refers to the presence of abnormal numbers of leukocytes that may appear with infection in either the upper or lower urinary tract or with acute glomerulonephritis. Usually, the WBC's are granulocytes, and their nuclei can be seen. White cells from the vagina, especially in the presence of vaginal and cervical infections, or the external urethral meatus in men and women may contaminate the urine. This will be confirmed with the urinalysis sticks. LOTS of substances can clump together or crystalize and form casts in the urine. Some are benign, others indicate severe kidney damage. We will only talk about a couple, and how they relate to UTIs RBC can clump together and form casts. An absence of casts does not rule out renal disease. Casts may be absent or very few in cases of chronic, progressive, generalized nephritis. Even in cases of acute renal disease, casts can be few or absent in a single sample since they tend be shed intermittently. Furthermore, casts are unstable in urine and are prone to dissolution with time, especially in dilute and/or alkaline urine. Look at these cast on the wall charts: RBC: The presence of this red blood cell cast in on urine microscopic analysis suggests a bacterial infection (UTI), tubular injury (e.g.: kidney stones) or more sever glomerular or renal tubular injury. RBC often clump together and form a cast. WBC: Pus in the urine. Possibly from a UTI, tubular injury, or a more serious problem. Hyaline or Protein casts: The factors which favor protein cast formation are low glomerular filtration rate, high salt concentration, and low ph, all of which favor protein denaturation and precipitation. Hyaline casts can be seen even in healthy patients.

14 Low power: Definitely see some RBCs. Are there any WBC? Medium power #1: Yes, there are WBCs, also. Medium power #2: Some RBCs have formed a cast Medium power #3: Hyaline casts are thin, elongated, smooth, transparent High power: Most WBCs are granulocytes, with neutrophils the most common.

15 Step 6. The Kidney Slide #1 Start by selecting a good slide. Several of our slides are of whole kidneys (small mammal), they are the best to use. Without putting the slide under the microscope, hold the slide up to the light. You can see the capsule, cortex, medulla with collecting ducts, and papillae. The cortex is the outer region, the medulla is the deeper one. #2 View the Cortical layer and the Renal Corpuscles, and medulla at low power Under the microscope, begin with slide on low power. Start in the cortex, near the capsule. Slowly move the slide tray towards the medulla, while noting the following (see accompanying image): The cortex has large numbers of renal corpuscles, discernible as round structures with a white space around them. That s the glomerulus surrounded by the Bowman s capsule. Moving the slide downward, towards the medulla, you can see the boundary between the 2 layers. Corpuscles are replaced tubes. As we move the slide even farther down, the papilla comes into view. If your lucky, you ll have prat of the minor calyx, also

16 #3 View the Cortical layer and the Renal Corpuscles at medium or high power You are here The somewhat higher magnification image below is a section of the cortex only. Note that although there are many corpuscles in the cortex, the bulk of its substance is composed of the various types of renal tubules(convoluted tubules). I will not ask you to know if they are proximal or distal. The renal corpuscle has two components. The round, hollow Bowman s Capsule (glomerular capsule) has a parietal layer of squamous epithelium, and inside that shell is found a capillary complex, the glomerulus. The intra-corpuscular space is called Bowman's space.

17 #4 View the lower Medullary layer at medium or high power The medulla contains the loops of Henle and collecting ducts where water reabsorption occurs. Down by the papilla we only have Collecting ducts. Note the even appearance of these structures.

18 Step 7. The Kidney Dissection Guide See separate document