Bile Salts: Overview, Function, Benefits, Topics, Function, Benefits
Bile is a yellow, brownish, or olive-green liquid produced by the liver. It has a pH of 7.6–8.6 and consists mostly of water, bile salts, cholesterol, a phospholipid called lecithin, bile pigments, and several ions. It is very important for digestion and emulsification of fats.
This Story also Contains
- What are Bile Salts?
- Type of Bile Salts
- Functions of Bile salts
- Mechanism of Action
- Hormonal Regulation of Bile Salts
- Clinical Significance of Bile Salts
- Exam Relevance of Bile Salts
- Tips, Tricks, & Mnemonics
- Bile Salts NEET MCQs
- FAQs on Bile Salts
Bile salts are steroid compounds that play a vital role in digestion and absorption of fats. Produced by the liver and stored in the gallbladder, they emulsify lipids, form micelles, and aid in the absorption of fat-soluble vitamins. Bile reflux may occur in conjunction with gastric acid refluxing into the oesophagus. Gastroesophageal reflux disease (GERD), a condition that involves irritation and inflammation of oesophagal tissue, may result from stomach reflux. This article includes functions, mechanism, hormonal regulation and clinical significance of bile salts. Bile salts are crucial for NEET and CBSE biology exams under Digestion and Absorption.
What are Bile Salts?
Steroid acids known as "bile salts" are primarily present in the bile of mammals and other animals. The liver produces a variety of bile salts by conjugating bile acids with taurine or glycine residues. These anions are known as bile salts.
Primary bile salt is made by the liver while secondary by salt is formed using bacterial activity in the colon.
Taurocholic acid, glycocholic acid, taurochenodeoxycholic acid and Glycochenodeoxycholic acid are the main bile salts present in the human body.
Bile salt is important for the digestion of fats and absorption of fat-soluble vitamins like vitamin A vitamin B vitamin E and vitamin K.
Bile and bile salts are stored in the gallbladder and released between meals.
Bile salts are regulated by hormones and also through receptors like FXR and TGRS.
Type of Bile Salts
There are two types of bile salts. Both of them along with their functions discussed below:
Type of Bile Salts | Explanation |
Primary bile salt |
|
Secondary bile salt |
|
Commonly Asked Questions
Conjugated bile salts are bound to amino acids (usually glycine or taurine), making them more water-soluble. Unconjugated bile salts are not bound to amino acids. Conjugated bile salts are more efficient in fat emulsification and less likely to be passively absorbed in the upper small intestine.
The amphipathic nature of bile salts, with both hydrophobic and hydrophilic regions, allows them to interact with both water and lipids. This property is crucial for their role in emulsifying fats and forming micelles.
Bile salt-dependent lipase, also known as carboxyl ester lipase, is an enzyme that requires bile salts for activation. It plays a crucial role in the digestion of dietary lipids, particularly those found in milk, making it especially important for infants.
Bile salts help solubilize dietary cholesterol, incorporating it into mixed micelles. This process is crucial for cholesterol absorption in the small intestine.
Bile salts aid in the digestion of phospholipids by emulsifying them and forming mixed micelles, which allows phospholipase enzymes to access and break down the phospholipids more efficiently.
Functions of Bile salts
Bile salts are responsible for various functions in the human body and some of the major functions are discussed below:
Helps break down lipids and absorbs the fat-soluble vitamins.
Bile salts trigger the gallbladder to release bile to the duodenum when dietary fats are present.
Bile salt also helps with digestion and the breakdown of dietary lipids which are excreted with toxins.
The required concentration of bile salt also helps in interacting with the receptors that regulate the metabolic functions of the hormones.
They also facilitate several digestive processes and are important for the absorption of minerals.
Mechanism of Action
The bile salts play the additional important role of removing the monoglycerides and free fatty acids. Bile salts, when high in concentration in water, have the ability to form micelles. Micelles are small spherical and cylindrical globules. These develop because each bile salt molecule is composed of a sterol nucleus that is highly fat-soluble and a polar group that is highly water-soluble.
These polar groups are negatively charged and allow the entire micelle globule to dissolve in the water and remain in stable solution until the fat is absorbed into the blood. The bile salt micelles also act as a transport medium to carry the monoglycerides and free fatty acids, both of which are relatively insoluble, to the brush borders of the intestinal epithelial cells. There the monoglycerides and free fatty acids are absorbed into the blood. The bile salts are released back into the chyme to be used again.
Hormonal Regulation of Bile Salts
The two main hormones involved in the regulation of bile secretion are:
Secretin: It is released from the duodenum when acidic chyme enters. It stimulates the liver to produce bile rich in bicarbonate, enhancing bile salt action.
Cholecystokinin (CCK): It is released in response to fatty food. It causes the gallbladder to contract and release bile (with bile salts) into the duodenum.
Clinical Significance of Bile Salts
Bile salts are essential for digestion and absorption of fats. Any disturbance in their secretion, formation, or flow leads to important clinical conditions:
Gallstone formation: Under abnormal conditions, the cholesterol may precipitate in the gallbladder, resulting in the formation of cholesterol gallstones. People on a high fat diet over a period of years are prone to the development of gallstones.
Vitamin deficiencies: Poor absorption of fat-soluble vitamins like Vitamin A, D, E, and K. The deficiency in these vitamins causes problems like night blindness, rickets, bleeding disorders, and nerve weakness.
Cholestasis: It is a condition in which bile is not able to flow from liver to intestine. This leads to the build up of bile in the blood.
Diagnostic marker: Bile salt levels in blood and urine can indicate malfunction of the liver.
Exam Relevance of Bile Salts
During exam preparation, different types of questions about the Bile Salts are asked. The table below contains the different patterns of questions asked in different exams.
Exam Type | Types of Questions Asked |
| |
| |
Paramedical |
|
Tips, Tricks, & Mnemonics
It takes effort to remember everything in a single go. We made the entire problem easy. Some of the tricks regarding Bile Salts are given below which you can use to memorise the important points.
Types of Bile Salts
"PS-SS: Primary and Secondary Salts"
P: Primary bile salts are produced in the liver (e.g., cholic acid and chenodeoxycholic acid).
S: Secondary bile salts are formed by bacterial action in the intestine (e.g., deoxycholic acid and lithocholic acid).
Functions of Bile Salts
"DEAL: Digestion, Emulsification, Absorption, Elimination"
D: Digestion of lipids by forming micelles.
E: Emulsification of fats to enhance their breakdown.
A: Aid in the absorption of fat-soluble vitamins (A, D, E, K).
L: Elimination of waste products (cholesterol and bilirubin) through faeces.
Mechanism of Action
"MICS: Micelles, Interface, Concentration, Solubility"
M: Micelles are formed at the critical micellar concentration.
I: Bile salts act at the lipid-water interface to solubilize fats.
C: The concentration of bile acids affects lipid digestion efficiency.
S: Increased solubility of conjugated bile salts enhances absorption.
Hormonal Regulation
"CGR: Cholecystokinin, Gallbladder, Release"
C: Cholecystokinin (CCK) stimulates bile release.
G: The gallbladder stores and releases bile salts during digestion.
R: Release of bile is triggered by the presence of fats in the digestive tract.
Clinical Significance
"DICE: Deficiency, Implications, Cholestasis, Emulsification"
D: Deficiency of bile salts can lead to fat malabsorption.
I: Implications of low bile salt levels include increased toxin accumulation.
C: Cholestasis can occur when bile flow is obstructed.
E: The emulsification capacity of bile salts is crucial for effective lipid digestion.
Bile Salts NEET MCQs
Q1. The main function of bile is to
Eliminate the waste products
Emulsify the fats
Digest proteins by enzymatic activity
Regulate the digestion process
Correct answer: 2) Emulsify the fats
Explanation:
The liver produces bile, which the gallbladder stores. In order to facilitate the further breakdown of lipids into fatty acids and glycerol by digestive enzymes like lipase, it primarily emulsifies fats by breaking them down into smaller droplets.
Remove trash: Bile's primary purpose is not to aid in the excretion of waste products such as bilirubin.
Break down proteins through enzymatic activity: Bile does not break down proteins directly. Enzymes such as trypsin in the small intestine and pepsin in the stomach perform this job.
Control the digestion process: Although bile has a part in digestion, it does not directly control it.
Hence, the correct answer is option 2) Emulsify the fats.
Q2. Assertion: Bile helps in the absorption of fat-soluble vitamins.
Reason: Bile contains bile salts that aid in the absorption of fat-soluble vitamins.
Assertion and reason are both true, and reason is an accurate account of assertion.
Both assertion and reason are accurate, but reason does not adequately explain assertion.
The assertion is correct, but the reasoning is incorrect.
Both the assertion and reason are incorrect.
Correct answer: 1) Assertion and reason are both true, and reason is an accurate account of assertion.
Explanation:
Bile plays an important role in the digestion and absorption of fats in the small intestine. The digestion of fats requires the emulsification of fat molecules into smaller droplets, which can then be broken down by lipase enzymes. Bile produced in the liver and stored in the gallbladder contains bile salts that emulsify fat and facilitate the action of lipase enzymes.
In addition to aiding the digestion of fats, bile also plays a crucial role in the absorption of fat-soluble vitamins such as vitamins A, D, E, and K. These vitamins are soluble in fats and require bile to be absorbed from the small intestine into the bloodstream. The bile salts in the bile surround the fat-soluble vitamins and help transport them across the intestinal wall and into the bloodstream.
Therefore, both the assertion and the reason are true, as bile salts in the bile to aid in the absorption of fat-soluble vitamins.
Hence, the correct answer is option 1) Assertion and reason are both true, and reason is an accurate account of assertion.
Q3. A young infant may be feeding entirely on mother's milk which is white in colour but the stools which the infant passes out are quite yellowish. What is this yellow colour due to ?
Bile pigments passed through bile juice
Undigested milk protein casein
Pancreatic juice poured into duodenum
Intestinal juice
Correct answer: 1) Bile pigments passed through bile juice
Explanation:
The young infant may be feeding on the mother's milk which is white but the stool the infant passes is yellowish due to the bike pigments: bilirubin and biliverdin which are obtained by the recycling of dead RBCs.
Hence, the correct answer is option 1) Bile pigments passed through bile juice
Also Read:
FAQs on Bile Salts
What are bile salts in biology?
Bile salts are amphipathic molecules i.e., having both hydrophilic and hydrophobic regions. They are derived from cholesterol in the liver. They are secreted into bile and stored in the gallbladder, then released into the small intestine during digestion. Bile salts act as biological detergents that help in digestion and absorption of fats and fat-soluble vitamins.
What are the functions of bile salts?
Emulsification of fats: Helps break down lipids and absorbs the fat-soluble vitamins.
Bile Release: Bile salts trigger the gallbladder to release bile to the small intestine
Absorption of lipids and vitamins: Essential for uptake of fat-soluble vitamins (A, D, E, K).
Regulate hormones: Helps in interacting with the receptors that regulate the metabolic functions of the hormones.
What are primary and secondary bile salts?
Primary bile salts are synthesized directly from cholesterol in the liver. e.g., cholic acid, chenodeoxycholic acid
Secondary bile salts are formed in the intestine by bacterial modification of primary bile salts. e.g., deoxycholic acid, lithocholic acid
How do bile salts help in emulsification of fats?
Bile salts have a hydrophilic side (water-loving) and a hydrophobic side (fat-loving). When they surround large fat globules in the intestine, they break them down into tiny micelles. This emulsification increases the surface area for pancreatic lipase to act, speeding up fat digestion. Without bile salts, fats would remain as large droplets and be poorly digested.
Frequently Asked Questions (FAQs)
Bile salts can influence the gut-brain axis by affecting the composition of the gut microbiome and by acting as signaling molecules. This interaction may have implications for various physiological processes and neurological conditions.
Bile salts can influence glucose metabolism by activating nuclear receptors like FXR, which regulate genes involved in glucose homeostasis. This suggests a potential role for bile salts in metabolic disorders like diabetes.
Bile salts facilitate the enterohepatic circulation of certain hormones, particularly steroid hormones. This process helps maintain hormone levels and prolongs their effects in the body.
Unlike long-chain fatty acids, medium-chain fatty acids do not require bile salts for absorption. They can be absorbed directly into the portal vein, bypassing the lymphatic system.
Bile salts help solubilize bile pigments (like bilirubin) in bile. This is important for the excretion of these waste products from the body through the feces.
Bile salts have antimicrobial properties that can disrupt the cell membranes of some enteric pathogens. They also promote the growth of beneficial bacteria, helping to maintain a healthy gut microbiome that can resist pathogen colonization.
Bile salts enhance the absorption of lipophilic nutrients by incorporating them into mixed micelles. This process is crucial for the efficient absorption of substances like fat-soluble vitamins and some phytochemicals.
Bile salts help regulate cholesterol synthesis through negative feedback. When bile salt levels in the liver are high, they suppress the enzyme HMG-CoA reductase, which is key in cholesterol synthesis.
Bile salts enhance the absorption of fat-soluble antioxidants like vitamin E and carotenoids by incorporating them into mixed micelles, facilitating their transport across the intestinal membrane.
Bile salts can influence energy metabolism by activating nuclear receptors like FXR, which regulate genes involved in glucose and lipid metabolism. This suggests a broader role for bile salts beyond just fat digestion.