Mammalian Kidney Investigation Background Information: The kidneys are dark red bean -shaped organs that are a very important pair of organs that perform many functions. The kidneys have a convex side and a concave side. They are each about the size of a fist. The kidneys are located near the middle back of a human, just below the rib cage, one on each side of the spine. One kidney is located below the spleen on the left side of the body, whereas the other kidney is located just below the liver.
The kidneys receive blood from the paired renal arteries and the blood is drained into the paired renal veins.In a human body, the kidneys process about 200 quarts of blood to sift out about 2 quarts of waste products and extra water everyday. Kidneys also produce various hormones. The function as two main functions- excretion and osmoregulation. Excretion is the process by which waste products and other non- useful materials are eliminated from an organism. Osmoregulation is active regulation of the osmotic pressure to maintain the homeostasis of the organism’s water content. In other word, it keeps the organism’s fluid from becoming too diluted or too concentrated.
Each of the kidneys is confined in a transparent membrane called the renal capsule. This protects the kidney again infections and distress. The substance of the kidney is divided into two distinct regions: an inner medulla and an outer cortex.
The renal medulla is made up of conical masses of tissue called renal pyramid. The bases of the renal pyramids are directed towards the convex surface of the kidney. The renal cortex forms a shell around the medulla. The tissues dip into the medulla between the adjacent renal pyramids to form renal columns.The granular appearance of the cortex is due to the random arrangement of tiny tubules associated with nephrons, the functional units of the kidney.
Nephrons are the most basic structure of the kidneys, it is a long, fine tubule around 30-55mm long and each kidney contains about one million of these structures. Nephrons are responsible for filtering the blood and removing the waste products. Research Question: From observations made in this experiment, what can be observed from the structure of the mammalian macroscopically and microscopically kidney is adapted to perform its function of excretion and osmoregulation?Aim: Part A: To investigate the macroscopic appearance the structure of the mammalian kidney in respect to its function of excretion and osmoregulation. Part B: To investigate the macroscopic appearance the structure of the mammalian kidney in respect to its function of excretion and osmoregulation. Hypothesis: The structure of the mammalian’s kidney is expected to have a certain structure adapted to perform its functions of excretion and osmoregulation. Apparatus: Part A: •1x sheep’s Kidney •Newspaper •1x Dissecting board •Paper towel 1x Scapel •1x Forceps •1x Ruler •Disposable rubber gloves & apron Part B: •Prepared slides of the kidney •1x Binocular microscope Method: Part A: 1.
Put on the apron and disposable gloves. 2. Wrap the dissecting board with the newspaper first then the paper towel on top of the newspaper. 3. Place the sheep’s kidney on the dissecting board. 4. Examine the outside shape of the sheep’s kidney and then draw the shape of the kidney.
5. Measure the dimensions of the kidney with a ruler and add them to the diagram of the shape of the kidney. Note any other structures attached to the kidneys and include these in the diagram. ) 6. After examining the exterior of the sheep’s kidney, use the scapel and cut the kidney in two longitudinally. 7. Study the different layers in the kidney and draw a sketch of the longitudinal section of the kidney with identifying all parts with labels.
Part B: 1. Set up the binocular microscope. 2. Obtain the prepared slide of the kidney and put it under the microscope. 3. Starting from the low power, examine the slide of the kidney while trying to identify all structures. .
Draw what can be seen from the slide. Variables: Part A Independent VariableThe position in which the kidney is longitudinally cut with the scapel. Dependent Variable The structure of the sheep’s kidney observed. Part B Independent VariableThe prepared slide and the region of that slide of the kidney used.
Dependent Variable The structure that can be observed from the microscope. Part A Controlled VariableMethod to control the variable The type of kidney used in this experiment. The kidney examine in this experiment is a kidney of a sheep.
Part BControlled VariableMethod to control the variable The type of microscope used in this experiment. Only one binocular microscope will be used in this part of the experiment. Part APart B Uncontrolled VariableUncontrolled Variable The health condition of the kidney The condition of the prepared kidney slides. Results: Qualitative data- Analysis of the kidney The size of the sheep’s kidney was around the size of a fist and the ureter was still attached to the concave side of the kidney.
Diagram 1 is the exterior of the kidney. The outside of the kidney was dark red in colour.The renal artery carries the blood into the kidney and the renal vein carries the blood away from the kidney. It was evident that at all layers of the kidney, the colours are different.
The renal cortex of the kidney, which is labeled in diagram 2(the interior of the kidney), was almost a brownish shade of red whereas the next layer closer to the centre of the kidney; the renal medulla was a much deeper shade of red. The most internal layer of the kidney, the pelvis was connected to the ureter. The colour of the pelvic was light pink.This change in colour of the different layers of the kidney could indicate that there is perhaps a difference in the distribution of blood vessels in each layer, with the medulla containing the most blood vessels as it is the deepest shade of red, then the cortex and then the pelvis containing the least. The functions of the kidney, excretion and osmoregulation require a sufficient amount of blood vessels. For example, as excretion is the process by which waste products and other non- useful materials are eliminated from an organism; the blood vessels assist with the transport of waste to the kidney to be excreted.
Also, as osmoregulation is active regulation of the osmotic pressure to maintain the homeostasis of the organism’s water content, absorption of water from the blood vessels can is controlled or maintained depending on the water balance. Therefore, it can concluded that the abundance of blood vessels in the kidney assist the kidney to carry out the kidney’s function of excretion and osmoregulation efficiently. The longitudinal section of the cortex of the kidney, which was microscopically observed, was drawn in diagram 3.According to diagram 3, many circular structures that are most likely the glomerulus, which are a tangled cluster of blood capillaries. The glomerulus is surrounded by thin, sac- like structure called the Bowman’s capsule. The Bowman’s capsule is an expansion at the closed end of a renal tubule. These structures enable the blood or any other materials to continuously move around each other and to collect filtrate from the glomerulus, passing it on to the rest of the nephrons. Conclusion:In conclusion, as both the main functions of the kidney, excretion and osmoregulation involve blood, as blood assists with the transport of waste to the kidney to be excreted and the active regulation of the osmotic pressure to maintain the homeostasis of the organism’s water content, depending on the water balance, it is evident that the abundance of blood vessels, which is shown by the difference in colours of the different layers of kidney is efficient for it to carry out it’s function.
Also, the tubular structures observed under the microscope enables the blood or any other materials to continuously move around each other and to collect filtrate from the glomerulus, passing it on to the rest of the nephrons. Evaluation: Errors/ LimitationsImprovements A limitation in this experiment is that only one type of mammalian kidney- a sheep’s kidney was investigated macroscopically in this experiment.As only one type of mammalian kidney- a sheep’s kidney was investigated in this experiment, the reliability of this experiment is not as reliable as it could be if the experiment involved dissecting various mammalian kidneys as it is impossible to assume that every single mammalian kidney is exactly the same. In order to improve this, dissections of the kidney of other mammals should be carried out for example a kidney of a dog or pig. Similarly, another limitation in this experiment is that only one type of mammalian kidney slide- a human kidney slide was investigated microscopically in this experiment.In the same way, as only one type of mammalian kidney slide- a human’s kidney slide was investigated in this experiment, the reliability of this experiment is not as reliable as it could be if the experiment involved dissecting various mammalian kidneys as it is impossible to assume that every single slide of mammalian kidney is exactly the same.
Similar to the limitation mentioned above, in order to improve this, microscopic analysis of the kidney of other mammals should be carried out for example a kidney of a dog or pig.