PRACTICAL 13 – KIDNEY DISSECTION

KIDNEY DISSECTION

PRACTICAL 13 – ÁNGELA SÁNCHEZ AND SORAYA REVILLA

1. OBJECTIVE

To explore externally and internally the mammalian kidney

2. MATERIALS

Pig kidneysHydrogen peroxide Dropper Utensils to cut and open it:

¡Eureka!

3. BASIS

ANATOMY OF THE URINARY SYSTEM

The organs of the urinary system include the kidneys, renal pelvis, ureters, bladder and urethra. The body takes nutrients from food and converts them to energy. After the body has taken the food components that it needs, waste products are left behind in the bowel and in the blood.The kidney and urinary systems help the body to eliminate liquid waste called urea, and to keep chemicals, such as potassium and sodium, and water in balance. Urea is produced when foods containing protein, such as meat, poultry, and certain vegetables, are broken down in the body. Urea is carried in the bloodstream to the kidneys, where it is removed along with water and other wastes in the form of urine.

Two kidneys: This pair of purplish-brown organs is located below the ribs toward the middle of the back. Their function is to: Remove waste products and drugs from the body - Balance the body's fluids - Release hormones to regulate blood pressure - Control production of red blood cells - Diagram of the bladder The kidneys remove urea from the blood through tiny filtering units called nephrons. Each nephron consists of a ball formed of small blood capillaries, called a glomerulus, and a small tube called a renal tubule. Urea, together with water and other waste substances, forms the urine as it passes through the nephrons and down the renal tubules of the kidney.

Two ureters. These narrow tubes carry urine from the kidneys to the bladder. Muscles in the ureter walls continually tighten and relax forcing urine downward, away from the kidneys. If urine backs up, or is allowed to stand still, a kidney infection can develop. About every 10 to 15 seconds, small amounts of urine are emptied into the bladder from the ureters.

Bladder. This triangle-shaped, hollow organ is located in the lower abdomen. It is held in place by ligaments that are attached to other organs and the pelvic bones. The bladder's walls relax and expand to store urine, and contract and flatten to empty urine through the urethra. The typical healthy adult bladder can store up to two cups of urine for two to five hours. Upon examination, specific "landmarks" are used to describe the location of any irregularities in the bladder. These are:- Trigone: a triangle-shaped region near the junction of the urethra and the bladder- Right and left lateral walls: walls on either side of the trigone- Posterior wall: back wall- Dome: roof of the bladder

Two sphincter muscles. These circular muscles help keep urine from leaking by closing tightly like a rubber band around the opening of the bladder. Nerves in the bladder. The nerves alert a person when it is time to urinate, or empty the bladder. Urethra. This tube allows urine to pass outside the body. The brain signals the bladder muscles to tighten, which squeezes urine out of the bladder. At the same time, the brain signals the sphincter muscles to relax to let urine exit the bladder through the urethra. When all the signals occur in the correct order, normal urination occurs

Functioning of the mammalian urinary system

Thousands of metabolic processes in myriad body cells produce hundreds of waste products. The urinary system removes them by filtering and cleansing the blood as it passes through the kidneys.Another vital function is the regulation of the volume, acidity, salinity, concentration, and chemical composition of blood, lymph, and other body fluids. Under hormonal control, the kidneys continually monitor what they release into the urine to maintain a healthy chemical balance. Disorders of the system can be subtle, so urination-related symptoms should be promptly reported.The urinary system is composed of a pair of kidneys, a pair of ureters, a bladder, and a urethra. These components together carry out the urinary system’s function of regulating the volume and composition of body fluids, removing waste products from the blood, and expelling the waste and excess water from the body in the form of urine. The two kidneys are reddish organs resembling beans in shape that are situated on either side of the abdomen just above the waist and towards the back of the body. The kidneys contain microscopic filtering units that remove waste, unwanted minerals, and excess water from the blood as urine. Each kidney is connected to the bladder by a long tube called a ureter, which transports urine away. The bladder is a hollow, muscular organ situated centrally in the pelvis; it stores urine until it is convenient to release it. At a certain volume, stretch receptors in its wall transmit nervous impulses that initiate a conscious desire to urinate. The urethra then conducts urine from the bladder to the outside.

Your urinary system filters your blood to get rid of what your body doesn’t need. It eliminates extra water and salt, toxins and other waste products. Different parts of the urinary system perform tasks, including: - Filtering blood. - Separating the toxins you don’t need from the nutrients you do need. - Storing and carrying pee out of your body.

Your kidneys are an essential part of filtering your blood. The urinary system works: 1. Your blood enters each kidney through lots of little arteries. 2. Your kidneys filter your blood, separating toxins from nutrients. 3. Vitamins, minerals, nutrients and proteins return back to your bloodstream. 4. Waste products and pee move from your kidneys through your ureters and to your bladder. 5. Your bladder stores your pee until you use the toilet. 6. Pee leaves your body through your urethra.

4. METHODOLOGY

1. Remove any grease that may cover the kidneys with your fingers and wash them properly under running water (they are usually sold without the grease that protects them from knocks). 2. Observe their shape and colour. Then feel the organ to determine its external texture. Locate, if possible, the ureter, renal vein and renal artery. 3. Carefully cut one of the kidneys longitudinally along the renal pelvis area. Identify the following structures: cortex, medulla, renal pelvis and the origin of the ureter. 4. Using a dropper, pour a small amount of hydrogen peroxide onto the freshly cut surface of the kidney. Effervescence will occur (the kidney is a catalase-rich organ). After a few seconds, remove the hydrogen peroxide by running your finger over the surface. You will see the marks on the renal tubes, collecting tubes and loops of Henle, where the bubbling process continues; this only occurs if the kidney is fresh.

5. RESULTS

PARTS:1. Right kidney 2. R 3. Ureter 4. Bladder 5. Inferior vena cava 6. inferior aorta 7. Urethra

PARTS:1. Capsule 2. Renal pyramids 3. Medulla 4. Calyx 5. Renal artery 6. Renal vein 7. Renal pelvis 8. Ureter

• What structures do you observe externally? Externally, the kidneys are surrounded by three layers. The outermost layer is a tough connective tissue layer called the renal fascia. The second layer is called the perirenal fat capsule, which helps anchor the kidneys in place. The third and innermost layer is the renal capsule.

• What structures are observed internally? Internally, we observed that the kidney has three regions; an outer cortex, a medulla in the middle, and the renal pelvis in the region called the hilum of the kidney. The hilum is the concave part of the bean-shape where blood vessels and nerves enter and exit the kidney; it is also the point of exit for the ureters.

• Can the glomeruli be observed in which area?We can observe the glomeruli, as it is a tuft of capillaries located within Bowman's capsule within the kidney. Glomerular mesangial cells structurally support the tufts.

• What is the colouring of the medullary zone and the cortical zone? What determines the difference between cortex and medulla? The outer, reddish region, next to the capsule, is the renal cortex. This surrounds a darker reddish-brown region called the renal medulla.The kidney is made up of solid tissue called parenchyma which consists of cortex and the medulla. The renal cortex is the outside section of the kidney, while the medulla is the inside section. The renal cortex has a more grainy texture, while the medulla is smoother.

• How many Malpighian pyramids are there in the medullaryzone? Another term for renal pyramids is malpighian pyramids. Between seven and eighteen pyramids exist in the innermost part of the kidney, which is called the renal medulla; in humans, there are usually only seven of the pyramids.

• What is the function of the ureters? These muscular tubes transport urine from the renal pelvis to the bladder. The ureter's muscular layers are responsible for the peristaltic activity that moves urine from the kidneys to the bladder.

• What is homeostasis and how are the kidneys involved? The kidneys regulate circulatory volume by controlling sodium and water balance, thus maintaining extracellular fluid volume (ECFV) homeostasis. Simply put, an increase in sodium and water consumption leads to an increase in ECFV, which in turn increases blood volume.

6. OBSERVATIONS

We could observe perfectly how the foam is created and goes out when we add some drops of hydrogen peroxide with the dropper. Yes, we expected this results! The experiment goes done correctly.

7. REFERENCES

7. REFERENCES

https://www.hopkinsmedicine.org/health/wellness-and-prevention/anatomy-of-the-urinary-system#:~:text=The%20organs%20of%20the%20urinary,bowel%20and%20in%20the%20blood. https://my.clevelandclinic.org/health/body/21197-urinary-system https://courses.lumenlearning.com/wm-biology2/chapter/kidneys/#:~:text=Externally%2C%20the%20kidneys%20are%20surrounded,layer%20is%20the%20renal%20capsule.