The Urinary Bladder: Structure and Function

The excretory system is quintessential in our bodies. It aids in the removal of waste metabolites and employs many organs to do this. The kidneys filter the toxins and this doesn’t get secreted as such. So what happens then? Well, the solid matter transforms in the intestine and gets excreted as faeces. And the rest gets stored in the urinary bladder as urine before excretion. Let’s look at the anatomy of the bladder to understand its function.

Anatomy of the Urinary Bladder:

The bladder is located below the bowel and is unique. It appears oval when full and flattened when empty. This feature is due to the presence of the transitional epithelial layer inside the bladder. So, in simple terms, it is an elastic organ. Externally the bladder is divided into:

  • Apex
  • Body
  • Fundus
  • Neck

Urinary Bladder

 

Does the bladder have openings or orifices? The answer is obviously yes. The need for this is to receive urine from the kidney and then expel it. So, the bladder has two openings near its apex for the ureters. And one orifice to connect with the urethra at the lower end. These three orifices together form the “trigon of the bladder”.

Another important feature of the bladder is the rugae. What are they? These are nothing but mucosa folds on the inner wall of the bladder. Their role, once again, is to assist in bladder expansion.

The bladder has a special muscle called detrusor muscle. What can possibly be its role? This muscle is vital for micturition. The bladder has stretch receptors on its wall. These get activated when the bladder becomes full. In response to this, our detrusor muscle contracts. Finally, this causes us to expel urine. The internal anatomical layers of the bladder are:

urinary blader

  • Epithelial layer
  • Lamina propria
  • Detrusor muscle
  • Soft tissue

 

The functioning of the urinary bladder:

The urinary bladder is solely responsible for the storage and expulsion of urine.  But how does it do this? Urine filtered in our kidneys enters the bladder via ureters. It gets stored in the bladder till the bladder reaches its maximum capacity, that is, 300-350ml. And on reaching this value, the bladder switches on the stretch receptors. These then send the signal to the Barrington nucleus in the brain stem. At last, our bladder contracts and urine expels.

 

Kidney: Structure and Function

August 12, 2020

1 responses on "The Urinary Bladder: Structure and Function"

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