Micturition Process

Micturition

Excretion is the process of removal of chemical wastes( mainly nitrogenous wastes) from the body. It plays a vital role in maintaining the homeostatic( steady-state) condition of the body and organs concerned with the formation, storage and elimination of urine constitute are " excretory system " (the urinary system is more appropriate than the excretory system for the removal of nitrogenous wastes product)


Micturition Meaning:

It's the process of discharging urine from the urinary bladder along the urinary tract from the body.


What is Micturition?

Micturition is the process of discharging urine from the human body. Human beings and animals have a specialised organ system for the discharge of the urine from the body. Urine is expelled from the urinary bladder through the urethra( in the penis in males, and directly in females) by the relaxing of the sphincter muscles located at the opening of the urinary bladder into the urethra under the impulse from the nervous system.  It also happens by relaxation of detrusor muscles after the voluntary relaxation of the sphincter muscles such a process is called Micturition 

Human beings and animals have an organised urinary system which consists of two kidneys ( right and left kidney located on either side of the backbone and protected by the last rib ), ureter, urinary bladder, sphincter muscles and urethra.

Micturition is also known as the voiding phase of the bladder. It lasts for a short time, and as the bladder stretches, its firing rate increases and this increases the urge for urination and sometimes micturition relaxation; thus it is sometimes called involuntary Micturition or involuntary urination. 

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Physical Properties 

Urine has a yellowish colour ( due to the presence of urochrome ), and also the colour varies with different diets. A healthy human beings urinate around 1 to 1.5 litres per day of urine but also varies with various conditions. Urine has a pH scale value between 5 to 8, i.e. it is slightly acidic ( pH scale value = 6) protein diet makes it acidic while vegetable diet makes it alkaline and on standing the smell of urine becomes strong, ammonium like due to bacterial activities otherwise faint smell and its specific gravity is 1.003 to 1.035 


Constituents of Urines 

The normal human urine consists of about 95% of water and 5% of solid wastes dissolved in it. The percentage of solid waste may slightly vary according to the food taken and the time after taking food. Still, usually these are approximately ( in grams per litre in urine) as follows:


Organic in (g/L)

Inorganic in (g/L)

Urea

2.3

Sodium chloride

9.0

Creatinine

1.5

Potassium chloride

2.5

Uric acids

Others

0.7

2.6

Ammonia

Others

0.6

2.5


Besides the normal constituents, the urine may pass out specific hormones and also certain medicines like antibiotics and the excess vitamins.


Micturition Process :

Micturition process has two processes in it:

  • Storage phase

  • Voiding phase


Storage Phase 

Urine is contained in the urinary bladder ( it acts as the primary storage organ ) is a balloon-shaped, hollow, muscular organ. A healthy urinary bladder can hold up to 16 ounces of urine for 2 to 5 hours easily, and there opening is tightly closed by sphincter muscles which also prevents the leakage of urine from urinary bladder and sphincter muscles facilitates the enter of urine from urinary bladder into ureter that allows the urine to pass outside the body


Voiding Phase 

Whenever the urine is filled in the urinary bladder, it triggers the muscles and nerves, which in turn stimulates the need for urination and the brain signals the urinary bladder to contract. The responses sent to the central nervous system by nerves in the urinary bladder encouraged by the filling of urine in the urinary bladder and the answer sent back by the central nervous system to nerves in the urinary bladder signals the incitement of the contraction of the urinary bladder. Through the opening of the urinary bladder into ureter and the urine is eliminated and the process is called Micturition, and the neural mechanism involved is called the micturition reflex 


Problems Associated with Micturition

There are many diseases related to the micturition process, and some of them are due to physical trauma or another physiological illness, and urination problems include initiating urination and bladder impairing bladder encrypting and urination inconvenience. Few of the diseased mentioned :

  • Detrusor Instability: It is a problem caused in which detrusor muscles contract without any reason. The muscles are responsible for the contraction of the urinary bladder and help in the processes of Micturition thus resulting is that it causes urination inconvenience

  • Urinary Retention: It is a problem in which the inability to urinate completely occurs and the onset may occur suddenly or gradually, and the cause can be urethra blockage nerve problem and weak bladder muscles.


Management of the Micturition Problem:

  • The factors in the environment that inhibit the Micturition should be absent. 

  • For a normal micturition the coordination of the parasympathetic,  sympathetic and somatic nerve as they help in the micturition process

  • The capacity of the bladder to hold urine should remain the same and regular.

  • Sphincters, detrusor and pelvic muscles should have normal muscle tone and functioning.

  • In any region of the urinary bladder and urinary tract, there should be no obstruction.


Key Points in Micturition

  • Urine is created and collecting in nephron or uriniferous tubule ( in the kidney ) and flows into ureter

  • Ureter  muscle facilitation of the smooth muscle contraction

  • The urine is stored in a hollow, elastic and muscular organ of the urinary bladder

  • The urine flows out through the urethra

  • The urine carries out waste from the body(mainly nitrogenous wastes if stored in the body may be very harmful and may even cause death )

FAQ (Frequently Asked Questions)

Q1. Define the Process of Micturition?

Ans. It's the process of discharging urine from the urinary bladder along the urinary tract from the body.

Q2. Mention any Three Disorders of Micturition Which Causes Urinary Incontinence?

Ans. Three disorders of the Micturition are :

  1. Detrusor instability

  2.  Urinary Retention

  3. Spinal cord trauma