The Liver & Excretion: The Body’s Processing Plant

What Does the Liver Do in Excretion?

• The liver is a multitasking organ that processes nutrients, breaks down harmful substances, and plays a key role in excretion by removing toxic substances from the body.

Key Roles of the Liver in Excretion

Process	What Happens
Deamination	Breaks down excess amino acids, which could not be absorbed in the blood, to form urea. The amino group is removed /((NH_2)/)
Urea Formation	Converts the nitrogen-containing part of amino acids into urea, which is sent to the kidneys.
Detoxification	Breaks down harmful substances like alcohol and drugs into harmless products.
Bile Production	Removes waste products like bilirubin, which is excreted in bile.

 

Deamination: Breaking Down Amino Acids

What is deamination?

• Deamination is the process of removing the nitrogen-containing part (amino group $NH_2$) of amino acids.
• This happens when there are more amino acids in the body than needed

 

 

1. Amino acids $\to$ Ammonia: 
   • The liver removes the amino group, forming ammonia, a toxic compound.
2. Ammonia $\to$ Urea: 
   • Ammonia is quickly converted into urea, a less harmful substance.

$$\text{Amino acid} \to \text{Ammonia} \to \text{Urea}$$

 

Why is this important?

• Urea is less toxic than ammonia and can be safely transported in the blood to the kidneys for excretion.

 

Detoxification in the Liver

• The liver neutralizes harmful substances like alcohol, drugs, and chemicals.
• These substances are broken down into harmless by-products and excreted in bile or urine.

Analogy: Think of the liver as a factory that processes waste materials and ensures they’re safely removed.