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Home > Conditions & Concerns > Specialties  > Nephrology > FAQs On Anatomy & Physiology

FAQs

Anatomy and Physiology

Where are the kidneys located? 

The kidneys are located in the abdomen, opposite the 12th thoracic and third lumber vertebral respectively. 

What is the average length and weight of the kidney? 

Each adult kidney weights 130 - 170 gms and they measure about 10-12 centimeters in length.

What is the appearance of the kidneys on a cut section?

If we take the section of the kidney it can be divided into two distinct regions the inner part called medula and the outer cortex. The inner medulla is composed of the 12 to 18 conical masses called the pyramids. The base of each pyramid is located on the cortico medullary boundary and the apex is directed towards the renal pelvis. The cortex contains the majority of the filtering units called the glomerulus.

How do the kidneys get their blood supply? 

Each kidney is supplied by a single artery which originates from the aorta at the level of the first lumbar vertebra. The artery then further divides into branches terminating in the afferent arteriole which ends in a fine capillary bed which is known as glomerulus. The glomerulus in turn is drained by efferent arteriole.

Highlights

  Human Organs      Transplantations      Act (HOTA)

Related Issues

(FAQs)

Anatomy and     Physiology

Fluid and     Electrolytes 

Urine Analysis 

Imaging and     Biopsy of 
    Kidneys 

Urinary Tract     Infection

Acute Renal     Failure  

Chronic Renal     Failure 

Hemodialysis 

Peritoneal     Dialysis

Renal     Transplantation 

Kidney Stones

Hypertension 

Diabetes and The       Kidney 

Polycystic     Kidney Disease     and Alport's     Syndrome

 Glomerulonephritis,     IgA Nephropathy,     Lupus Nephritis

Nephrotic     Syndrome 

What is a Nephron?

The nephron is the functional unit of the kidney and there are approximately 120,000 nephrons in each human kidney. Each is composed of the glomerulus and the Bowman's capsule and is attached to the tubule. The tubule contains several distinct and anatomical and functional segments which are called as proximal tubule, loop of Henle, distal convoluted tubule and the collecting tubule. 

What is the mesangium of the kidney?

The space between the capillary network is called the mesangium of the kidney.

How do the Kidney's form urine? 

The kidneys receive about 25% of the blood from the heart or approximately 1.1 liters of blood per minute. As the blood flows from the arteries into the capillaries and finally into the glomerular capillaries a pressure is generated called the hydrostatic pressure or force which results in filtration of blood across the capillaries into the Bowman's space. This is called as glomerular filtration. The filtrate that exists from the Bowman's space further gets into the tubules. The tubules are mainly concerned with the absorptions of water, exchange of ions, which ultimately results in the formation of urine. 

What functions do the kidneys perform?

The kidneys play central role in the maintenance of the volume and the ionic composition of the body fluids known as the homeostasis. 

	Maintenance of electrolyte composition of body fluids.
	Maintenance of normal volume status of the body.
	Maintenance of normal blood pressure by way of the renin -angiotensin system.
	Excretion of metabolic waste products. E.g. - Urea, Uric Acid, creatinine, sulfates, phosphates
	Detoxification and elimination of toxins, drugs and their metabolites.
	Control of the manufacturing of the Red Blood cells by elaborating the hormone called as the Erythropoeitin.
	Control of mineral metabolism mainly calcium and phosphorus.

What is urea and creatinine?

Urea is the ultimate waste product of protein metabolism. Muscle contains a protein called creatin. It is broken down to creatinine and excreted in the urine.

What are the normal levels of creatinine and urea in the blood?

Normal urea level: Normal 15-40 mg/dl
Normal creatinine level: Normal is 0.2-1.3 mg/dl 

What does a high creatinine level signify?

When the kidneys fails creatinine levels in the blood go up. Thus the serum creatinine is used as a measure of the kidney function.

How do the kidneys help in regulating the calcium in the body?

The active form of Vitamin D is formed in the kidney. It's function is to regulate the absorption of calcium from the intestine. 

Why do patients with renal failure become anemic?

The kidneys manufacture a hormone called Erythropoeitin which is involved in the production of red blood cells. In chronic renal failure the Erythropoeitin production by the kidneys decreases and the patient becomes anemic.

What is the renin-angiotensin system?

Whenever there is a sustained fall in blood pressure, the decreased blood supply to the kidneys stimulates the release of renin. Renin is converted to angiotensin. Angiotensin has the following effects:

1. It constricts the blood vessels, mainly veins.

2. It stimulates the release of aldosterone which helps retain sodium and water.

Thus the blood pressure is restored to normal.