Bowman’s Capsule

What is Bowman’s capsule?

Bowman’s capsule is a part of each filtering unit (nephron) in your kidney. You have about 1 million nephrons that filter blood in each of your two kidneys. Kidneys clean blood and return it to your body.

Every nephron has a glomerulus. A two-walled pouch, Bowman’s capsule covers the glomerulus. This group of tiny blood vessels is the starting point for filtering waste products out of your blood. Bowman’s capsule and the glomerulus make up the renal corpuscle.

You may hear other names for Bowman’s capsule, like:

• Glomerular capsule
• Malpighian capsule
• Renal corpuscular capsule

The space in between the walls (layers) of Bowman’s capsule is called Bowman’s space. You may hear healthcare providers refer to Bowman’s space as:

• Glomerular capsule space
• Filtration space
• Urinary space

What is the function of the Bowman’s capsule in the kidney?

The function of Bowman’s capsule is to help the glomerulus filter blood. Small molecules from your blood pass freely into Bowman’s space. Cells and large proteins stay in your blood.

The glomerular capsule also protects cells called podocytes by keeping white blood cells from getting in. White blood cells can’t pass through Bowman’s capsule. Podocytes in a kidney capsule have pedicels that manage what stays and what goes. Finger-like pedicels link together like they’re holding hands. The way they join creates slits that only let certain things go through. When you’re healthy, protein and cell content can’t get through.

The small molecules then pass through tubes in your kidney. Your kidney regulates which molecules your blood absorbs and which leave your body in pee (urine).

Waste materials go out of your body as urine through tubules (tiny tubes). The blood pressure in the glomerulus helps move the blood along. As the fluids leave, water and nutrients go back into your blood.

Two arterioles go into the Bowman’s capsule. One brings blood into the glomerulus. The other lets blood out.

Where is Bowman’s capsule located?

Bowman’s capsule is in the renal cortex, part of your kidney. Your kidneys are in your back, below your rib cage. Usually, you have one kidney on either side of your spine. Your kidneys are between your intestines and diaphragm. Each kidney connects to your bladder by a tube called a ureter.

What does it look like?

Bowman’s capsule looks like a pouch, sac or cup. You can only see it under a microscope. Bowman’s capsule contains fluid like blood plasma, but with no red or white blood cells or platelets.

What are the parts of Bowman’s capsule?

The glomerular capsule has two layers. A type of body tissue, simple squamous epithelium, makes up the outer (parietal) layer. These parietal cells give structure to Bowman’s capsule. Cells called podocytes form the inner (visceral) layer.

What are the common conditions and disorders that affect Bowman’s capsule?

Diseases and conditions that affect your kidneys also affect Bowman’s capsule. This glomerular capsule is especially at risk of diseases of the glomeruli. These are the small blood vessels that Bowman’s capsule surrounds.

Glomerular diseases can damage glomeruli. They don’t work well when they’re inflamed, swollen, scarred or hardened. Without treatment, these diseases can result in kidney failure.

Signs/symptoms something isn’t working right

Contact your healthcare provider if you’re having signs and symptoms of kidney issues, like:

• Changes in your urine
• Changes in how often you pee
• Fatigue (extreme tiredness)
• High blood pressure (hypertension)
• Muscle cramps
• Poor appetite or metallic taste of food
• Nausea and vomiting
• Swelling, especially around your ankles or hands

Providers use several tests to measure kidney function and diagnose kidney problems. Tests may include:

• Blood tests: These can show how well your glomeruli filter your blood.
• Urinalysis: This measures specific substances, like protein or blood, in urine.
• Imaging tests like ultrasound: These let your providers examine the size and shape of your kidneys.
• Kidney function tests: These tests show how well your kidneys are working.
• Kidney biopsy: In this test, your provider removes a small amount of kidney tissue to examine under a microscope.

Simple lifestyle tips to keep Bowman’s capsules healthy

You need all the parts of your kidney to work well, including Bowman’s capsule. If a glomerular capsule fails, that affects its ability to filter blood.

You can help keep Bowman’s capsule healthy by taking care of your kidneys. It’s important to have regular checkups and blood and urine tests to monitor your kidney health. This is especially true if you have high blood pressure, obesity and/or diabetes.

You can reduce your risk of developing a kidney problem by:

• Avoiding tobacco products
• Cutting out excess salt
• Increasing daily physical activity
• Limiting your use of nonsteroidal anti-inflammatory drugs
• Maintaining a weight that’s healthy for you
• Monitoring your blood pressure levels
• Watching your blood sugar levels if you have diabetes