What is a Kidney? | where are the kidneys in the body?

What is a Kidney
What is a Kidney

What is a Kidney? | where are the kidneys in the body?

•Kidneys are reddish-brown bean-shaped organs situated on both left and right sides of the retroperitoneal space.
•These are found only in vertebrates- mammals, birds, reptiles, amphibians, and fishes.
•In the human body, the length of a kidney is 12 centimeters.
•Kidneys lie in the upper part of the abdominal cavity.
•Kidneys lie on either side of the spine asymmetrically in the retroperitoneal position.
•The position of the liver causes elevation of the left Kidney at a certain level. Compared to the right Kidney, it is slightly placed outwards in the middle.
Failure of the Kidney can cause you to do dialysis or kidney transplant surgery.

Functions of the Kidneys: 
The Kidney is a part of the Urinary System and the Endocrine System.


As a part of the Endocrine system, the Kidneys perform the function of
•The Kidneys convert a precursor of vitamin D to its active form, calcitriol.
•Synthesizes the hormone erythropoietin which is an active member in red blood cell production and renin.
•Kidneys help in the production of red blood cells and are responsible for bone health.

As a part of Urinary System, the Kidneys perform the function of
•Filtering blood before passing it to the heart
•Maintaining acid-base level of the blood.
•Regulating and filtering minerals from blood

How do Kidneys filter out Urine?

•At the renal corpuscle, blood gets filtered out. Cells and large proteins are retained while the smaller molecular weight materials get filtered out from the blood.
•The result of filtration is ultrafiltrate. A healthy Kidney produces 180 L of ultrafilterate everyday.

•The ultrafilterate enters the peritubular capillary. Glucose, water and the forms amino acids are reabsorbed by selective receptors.

•Kidney contains 1 million nephrons. A nephron consists of a filtering unit of blood vessels known as glomerulus. Glomerulus is attached to a tubule. The ultrafilterate enters glomerulus and gets filtered to enter the tubule. Chemicals along with the water are either added or filtered as per as the needs.

•The final ultrafilterate gets into the collecting tube. The ultrafilterate can now be called as Urine. As each Kidney is attached to a ureter, it gets collected in tube that passes the excretion to the bladder.

In the case of a Kidney failure, person is unable to throw waste out of their bodies. In extreme cases, a kidney transplant may take place in extreme cases.

What causes Improper functioning of the Kidneys?

1. Diabetes: Diabetes occurs when there is high blood glucose in the body and there isn’t enough production of insulin by the pancreas to get blood glucose utilized by the cells. High blood glucose further damages the ability of the Kidney to filter out waste from blood. This condition is known as Diabetic nephropathy or diabetic kidney disease.

2. High blood pressure or Hypertension: High blood pressure occurs when heart applies more pressure against the wall of arteries. High Blood Pressure happens when the heart has to work more than normal. Reasons could be lack of physical activity and unhealthy lifestyle. High blood pressure eventually narrows down blood vessels. This further causes the improper functioning of the Kidneys.

3. Glomerulonephritis: Glomerulonephritis occurs due to the inflammation of tiny filtering units called glomeruli in nephrons. This will hinder ability of nephrons to take out waste materials from the ultrafilterate. Glomerulonephritis is acute and chronic. Acute Glomerulonephritis may later develop into Chronic Glomerulonephritis.

4. Polycystic Kidney disease: Non-cancerous cysts develop on kidneys that enlarge over time. They may be inherited and they cause the Kidneys to work improperly.

5. Kidney Stone: A Kidney stone is a formation of a deposit of minerals and acid salts. The reason for the formation of a stone could be inherited or may be a result of too much absorption of calcium from food and excess phosphorus from meat. A person can withstand a small kidney stone but its excess may cause Kidney Failure leading to a kidney transplant.

6. Interstitial Nephritis: It is the inability of the Kidney to filter waste as the spaces between the tubes inside the Kidney get inflammed.

7. Renal Artery Stenosis: It is the blockage that occurs in the blood vessels that carry blood to the Kidneys.

8. Inheritance: Improper functioning of the Kidney can run through the families like heart attacks.

What happens at the time of kidney failure?
Symptoms as mentioned on the website.

Tests that check the health of your kidney
You should get yourself tested if you have any of the following
•Heart disease
•High blood pressure
•Family history of Kidney malfunction/disease

Tests kidney problems
1. Estimated glomerular filtration rate: This test specifies the ability of a kidney to filter out blood.
•eGFR of 90 or more is the healthiest range.
•eGFR of 60-89 is a mild stage of Kidney disease.
•eGFR of 45-59 is a moderate Stage 3A of Kidney disease

•eGFR of 30-44 is a moderate Stage 3B of Kidney disease
•eGFR of 15-29 is a Stage 4 Severe Kidney disease
•eGFR less than 15 is a Kidney failure: Kidney Failure Final Stage/Stage 5
A person is likely to pass away after reaching the final stage in a few months if left untreated. This person needs to have a lot of time as a kidney transplant recipient because it takes time to find the right donor. What is a Kidney

2. Urine Albumin test: Proper functioning of the Kidney never lets the protein to be filtered out of the body as waste. This protein is called as albumin and the health care practitioners check for albumin in the urine.
•Less than 30 mg is normal
•30-300 mg may indicate early kidney disease.
•More than 300 mg indicates more-advanced kidney failure.

What is the treatment of Kidney Failure?
The ultimate failure of the Kidney has two major treatments.

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1) Dialysis:
Dialysis is the process of filtration of blood by a machine known as dialyser or oftenly called an artificial kidney.
Dialysis removes excess water, solutes and toxins from the blood of a person whose kidneys can no longer filter out waste from blood to produce urine.

This type of dialysis is done three-four times a week either at the patient’s home or at the dialysis unit. What is a Kidney
This process takes 3-5 hours to complete.
Blood is taken out from the body of the patient and cleaned out in the dialyser.
Then, it returns to the patient’s body.
Suitable for people who have too low kidney function.

Peritoneal Dialysis
A few weeks before the peritoneal dialysis, a healthcare practitioner places a soft tube known as catheter in the patient’s abdomen lining or in belly.
Continuous Peritoneal Dialysis: The patient can do this themselves. The dialysis solution flows through a bag to the catheter. What is a Kidney

It stays 4-6 hours inside the belly to carry out the filtration process. The patient can move around and continue daily activities. The solution is later drained out using an empty bag. This process can be done 4-6 times in a single day. What is a Kidney

Automated Peritoneal Dialysis: This happens overnight as the patient can sleep. The dialysis is performed 4-5 times in a night. The machine performs the dialysis is called a cycler. Patient can carry the solution in the morning in their belly and can get filtered out in the afternoon. What is a Kidney

2) Kidney Transplant
Kidney transplant is a surgical procedure that involves placing either a healthy donor’s Kidney or a deceased donor’s into the patient whose Kidney’s can no longer perform urinary and endocrine functions.
The donor could be a family member, friend or an unknown person.
Not everyone’s Kidney is compatible to the patient who requires a kidney transplant.

1) Why should I choose Kidney Transplant over dialysis?
Answer: Dialysis is a lifelong treatment that causes you a disruption in the normal lifestyle. Dialysis can be physically and mentally draining as hinders your physical activity. Moreover, it only performs over 10-20% of your kidney function. What is a Kidney

Kidney transplant can give you a longer lifetime than dialysis ranging from 8-20 years. So, kidney transplant success rate is much higher than dialysis. What is a Kidney
After kidney transplant recovery period, you can get back to your healthy lifestyle.

2) How is the donor’s Kidney compatible to mine?
Answer: A donor does not need to be a family member or a relative, the donor could be a completely unrelated stranger.
There are a few tests done before finding the perfect donor. What is a Kidney

1. ABO compatibility
•Donors with blood group A can donate a kidney to recipients with blood group A and AB.
•Donors with blood group B can donate a kidney to recipients with blood group B and AB.
•Donors with blood group O can donate a kidney to recipients with blood group O, A, B and AB.
•Donors with blood group AB can only donate a kidney to recipients with blood group AB.

2. HLA Typing or Tissue Typing
Antigens are the protein on the cells of the body. There are over 100 types of antigens in a human body. We have our antigen matched with our parents and siblings. Having matched antigens with an unrelated person is an improbable event.

People with no antigen match can also go for kidney transplants but the important part is antibodies. Donor with a history of transfusions, pregnancy, miscarriages and other infections are likely to develop antibodies. Making antibodies against the other person’s HLA results in rejection of the match. HLA test should be negative cross-match for successful transplantation. What is a Kidney

3. Serum Crossing
A serum cross match test is a blood test that donor and recipient undergo several times before the transplantation. Even the day before. Donor cells are mixed with the recipient’s serum. If recipient develops antibodies against the donor cells, donor cells would be destroyed and the transplantation does not proceed further, gets cancelled. This is a part of kidney transplant aftercare.



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