Biology ORGANS AND DISORDERS IN EXCRETION

KEY TOPICS

`star` Micturition
`star` Role of Other organs in Excretion
`star` Disorders of the Excretory System

MICTURITION

● `color{violet}("Urine formed")` by the `color{violet}("nephrons")` is ultimately carried to the `color{violet}("urinary bladder")` where it is stored till a voluntary signal is given by the `color{brown}("central nervous system (CNS).")`

● This signal is initiated by the stretching of the `color{violet}("urinary bladder")` as it gets filled with urine.

● In response, the `color{brown}("stretch receptors")` on the walls of the `color{violet}("bladder")` send `color{violet}("signals")` to the `color{violet}("CNS.")`

● The `color{violet}("CNS")` passes on motor messages to initiate the `color{brown}("contraction of smooth muscles")` of the `color{violet}("bladder")` and simultaneous relaxation of the urethral sphincter causing the release of `color{violet}("urine.")`

● The process of release of `color{violet}("urine")` is called `color{brown}("micturition")` and the `color{violet}("neural mechanisms causing")` it is called the `color{brown}("micturition reflex.")`

● An adult human excretes, on an average, `color{brown}("1 to 1.5 litres")` of `color{violet}("urine")` per day.

● The `color{violet}("urine")` formed is a light yellow coloured watery fluid which is slightly `color{violet}("acidic (pH-6.0)")` and has a characterestic odour.

● On an average, `color{brown}("25-30 gm")` of `color{violet}("urea")` is excreted out per day.

● Various conditions can affect the characteristics of `color{violet}("urine.")`

● Analysis of `color{violet}("urine")` helps in `color{violet}("clinical diagnosis")` of many `color{violet}("metabolic discorders")` as well as malfunctioning of the `color{violet}("kidney.")`

● For example, presence of glucose ( `color{brown}("Glycosuria")`) and ketone bodies ( `color{brown}("Ketonuria")`) in urine are indicative of `color{brown}("diabetes mellitus.")`

ROLE OF OTHER ORGANS IN EXCRETION