Excretion is a life process which is as important as nutrition. In animals including humans, as a part of metabolism, many waste products are produced. Animals excrete them in different forms such as urine, sweat, faeces, and tears. Among these, the usual form of excreta, urine, is produced and discarded from our body as fluid. The process of urination is called micturition.
Let us have a brief look at the different stages and physiology of micturition.
“Micturition is the process of urine excretion from the urinary bladder.”
What is Micturition?
Micturition is the mode of excretion of urine from the body. Many waste products are excreted from the human body in the form of urine. Animals and humans have a specialized system of organs known as the excretory system to eliminate the waste products from the body.
The human excretory system consists of a pair of kidneys and ureters, a urinary bladder, and a urethra. The kidneys play a major role in the process of urine formation and its excretion. The urine formed is stored in the urinary bladder.
Micturition is also known as voiding phase of bladder control and lasts for a short time. As the bladder becomes full, the stretch receptors increase their firing rate. This increase the urge to urinate and causes micturition reflex. It sometimes even causes involuntary urination.
Also Read: Excretory Products and their Elimination
On average, a normal adult excretes 1 to 1.5 L of urine per day. Normal human urine is a light yellow fluid majorly consisting of 95 per cent water and 5 per cent solid wastes. It is slightly acidic with a pH close to 6.
Many endocrinal disorders can be diagnosed through urine analysis. For example, if a patient suffers from diabetes, the presence of glucose and ketone bodies in the urine can help detect the disease. Thus it is a major clinical diagnostic element.
Also Refer: Urine Formation And Osmoregulation
Micturition process consists of two phases:
- the storage phase
- the voiding phase
The urinary bladder is a balloon-shaped, hollow, muscular, organ that acts as the storage organ for urine. The urinary bladder in a healthy urinary system can store up to 16 ounces of urine for 2 to 5 hours easily. The circular sphincter muscles prevent the urine from leakage. They close tightly around the opening of the bladder into the tube (urethra) that allows the passage of urine outside the body.
When the bladder is filled with urine, the nerves in it are triggered, which in turn stimulates the need to urinate. The brain signals urinary bladder to contract. The receptors of the urinary bladder send a signal to the central nervous system, in response to which the nervous system sends a signal that incites the contraction of the urinary bladder. Through the urinary opening at the urethra, the urine is eliminated and the process is called micturition. The neural mechanism involved is called the micturition reflex.
Also Read: Urine Infection Symptoms
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