The Human Liver
The liver is the second biggest (after the skin) organ in the human body and the biggest gland (weighing an average of 1500 g).
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- It lies under the diaphragm in the right upper abdomen and mid-abdomen and extends to the left upper abdomen.
- The liver has the general shape of a prism or wedge, with its base to the right and its apex to the left.
- It is pinkish-brown in color, with a soft consistency, and is extremely vascular and quickly friable.
- The liver has two large areas, called the right and the left lobes.
- The gallbladder lies under the liver, along with parts of the pancreas and intestinal tracts.
- The liver and these organs interact to digest, absorb, and process food.
The liver holds about one pint (13%) of the body’s blood supply at any given minute. The liver consists of 2 primary lobes. Both are comprised of 8 segments that consist of 1,000 lobules (little lobes). These lobules are connected to small ducts (tubes) that connect with bigger ducts to form the common hepatic duct. The typical hepatic duct transports the bile made by the liver cells to the gallbladder and duodenum (the first part of the small intestine) using the common bile duct.
Functions of Liver
The liver manages most chemical levels in the blood and excretes a product called bile. This helps carry away waste items from the liver. All the blood leaving the stomach and intestines goes through the liver. The liver processes this blood and breaks down balances, and produces the nutrients, and also metabolizes drugs into forms that are simpler to utilize for the rest of the body or that are nontoxic. More than 500 crucial functions have actually been related to the liver. Some of the more well-known functions include the following:
- Production of bile, which helps carry away waste and break down fats in the small intestine throughout digestion.
- Production of certain proteins for blood plasma.
- Production of cholesterol and special proteins to assist carry fats through the body.
- Conversion of excess glucose into glycogen for storage (glycogen can, later on, be transformed back to glucose for energy) and to stabilize and make glucose as required.
- Processing of hemoglobin for use of its iron material (the liver stores iron).
- Resisting infections by making immune factors and removing bacteria from the bloodstream.
- Clearance of bilirubin, also from the red cell. If there is an accumulation of bilirubin, the skin and eyes turn yellow.
Liver in Homeostasis (Urea Cycle)
The liver is the central station of metabolism and subsequently the body’s main metabolic cleaning house. Due to this specificity, liver functions are critical to homeostasis and include interaction with the majority of the body’s organ systems.
The liver supports the excretory role of the kidney by detoxifying lots of chemical toxins and produces ammonia, urea, and uric acids from the nitrogen of amino acids. Among the different nitrogenous wastes, urea is the primary excretory product, and the liver forms it from the waste nitrogen.
Urea Cycle
The metabolic pathways associated with the production of urea are called the urea cycle. Two ammonia and one CO2molecules are shunted into the cycle to generate one molecule of urea. One ammonia molecule combines with carbon dioxide and currently available precursor from previous cycle ornithine to form citrulline, subsequently.
Another ammonia combines to form arginine. The arginine is split by arginase to form urea and the precursor ornithine for the next cycle.
Urea is detoxified form of ammonia in the urea cycle, which can be kept in the body in higher amounts than ammonia and can be removed with 1/10 amount of water as compared to ammonia.
The liver is not just associated with the synthesis of nitrogenous wastes to assist kidney in their disposal, however, also has various important functions of homeostasis importance. These functions come from synthesis, storage, conversion, recycling, and detoxification categories.
Multiple-Choice Questions (MCQs) with Answers
- What is the liver’s position in the human body?
- A) Left upper abdomen
- B) Right lower abdomen
- C) Right upper and mid-abdomen
- D) Left lower abdomen
- Answer: C
- How much of the body’s blood supply does the liver hold at any given moment?
- A) One quart (25%)
- B) Half a pint (6.25%)
- C) One pint (13%)
- D) Two pints (50%)
- Answer: C
- What is the color of the liver?
- A) Blue
- B) Pinkish-brown
- C) Green
- D) Red
- Answer: B
- What is the primary function of bile produced by the liver?
- A) Neutralizing stomach acid
- B) Breaking down carbohydrates
- C) Carrying away waste and breaking down fats during digestion
- D) Aiding in protein synthesis
- Answer: C
- How many lobules are there in a liver, each comprised of small lobes called?
- A) 500 lobules, hepatic ducts
- B) 800 lobules, bile ducts
- C) 1000 lobules, hepatic ducts
- D) 1200 lobules, bile ducts
- Answer: C
- What is one of the liver’s roles in homeostasis?
- A) Pumping blood to the heart
- B) Synthesizing urea and uric acids
- C) Producing red blood cells
- D) Storing glucose
- Answer: B
- Which nitrogenous waste is the primary excretory product formed by the liver?
- A) Ammonia
- B) Urea
- C) Uric acid
- D) Hemoglobin
- Answer: B
- What is the metabolic pathway associated with the production of urea called?
- A) Uric Acid Pathway
- B) Ammonia Detoxification Cycle
- C) Nitrogenous Recycling Cycle
- D) Urea Cycle
- Answer: D
- How many ammonia molecules are shunted into the urea cycle to generate one molecule of urea?
- A) One
- B) Two
- C) Three
- D) Four
- Answer: B
- Which precursor combines with ammonia to form citrulline in the urea cycle?
- A) Arginine
- B) Ornithine
- C) Urea
- D) Hemoglobin
- Answer: B
- What is the detoxified form of ammonia in the urea cycle?
- A) Uric Acid
- B) Citrulline
- C) Urea
- D) Ornithine
- Answer: C
- What does the liver store in terms of iron?
- A) Hemoglobin
- B) Ferritin
- C) Iron oxide
- D) Iron sulfate
- Answer: A
- What is the liver’s role in resisting infections?
- A) Producing antibodies
- B) Storing white blood cells
- C) Making immune factors and removing bacteria from the bloodstream
- D) Neutralizing viruses
- Answer: C
- What percentage of the body’s blood supply does the liver hold at any given moment?
- A) 25%
- B) 13%
- C) 50%
- D) 6.25%
- Answer: B
- What organ lies under the liver along with parts of the pancreas and intestines?
- A) Kidney
- B) Spleen
- C) Gallbladder
- D) Stomach
- Answer: C
- How is the liver’s general shape described?
- A) Spherical
- B) Cuboidal
- C) Prism or wedge
- D) Cylindrical
- Answer: C
- What is the liver’s role in the digestion process?
- A) Producing stomach acid
- B) Absorbing nutrients
- C) Breaking down and processing food
- D) Filtering blood
- Answer: C
- Which part of the small intestine does the common hepatic duct transport bile to?
- A) Duodenum
- B) Jejunum
- C) Ileum
- D) Colon
- Answer: A
- What happens if there is an accumulation of bilirubin in the body?
- A) Skin and eyes turn yellow
- B) Skin becomes pale
- C) Increased heart rate
- D) Excessive sweating
- Answer: A
- What is the liver’s function related to cholesterol and fats?
- A) Producing cholesterol for energy
- B) Storing fats in adipose tissue
- C) Producing special proteins to carry fats through the body
- D) Breaking down fats during digestion
- Answer: C
- What is the liver’s main role in blood plasma?
- A) Transporting oxygen
- B) Coagulation
- C) Producing proteins
- D) Breaking down red blood cells
- Answer: C
- Which organ does the liver support in its excretory role by detoxifying chemical toxins?
- A) Kidney
- B) Spleen
- C) Lungs
- D) Heart
- Answer: A
- What does the liver convert excess glucose into for storage and later use?
- A) Glycogen
- B) Fructose
- C) Glucagon
- D) Glutamine
- Answer: A
Frequently Asked Questions (FAQs) – The Human Liver
- What is the size of the liver in the human body, and where is it located?
- Answer: The liver is the second-largest organ, weighing an average of 1500 g. It is located under the diaphragm in the right upper abdomen, mid-abdomen, and extends to the left upper abdomen.
- How is the liver’s shape described, and what are its color and consistency?
- Answer: The liver has the general shape of a prism or wedge, with its base to the right and apex to the left. It is pinkish-brown in color, with a soft consistency and is extremely vascular and friable.
- What are the primary lobes of the liver, and how are they connected?
- Answer: The liver has two large areas, the right and left lobes, each comprised of 8 segments containing 1,000 lobules. Small ducts connect these lobules to form the common hepatic duct.
- What is the role of the common hepatic duct in liver function?
- Answer: The common hepatic duct transports bile made by liver cells to the gallbladder and duodenum (the first part of the small intestine) via the common bile duct.
- How much of the body’s blood supply does the liver hold, and what happens during digestion?
- Answer: The liver holds about one pint (13%) of the body’s blood supply. It processes blood from the stomach and intestines, breaking down, balancing, and producing nutrients during digestion.
- What are some well-known functions of the liver related to blood plasma and proteins?
- Answer: The liver produces bile for waste removal, certain proteins for blood plasma, cholesterol, and special proteins to carry fats through the body.
- What is the liver’s role in glucose metabolism and storage?
- Answer: The liver converts excess glucose into glycogen for storage, which can be later transformed back into glucose for energy. It also helps stabilize and make glucose as needed.
- How does the liver contribute to the body’s resistance to infections?
- Answer: The liver produces immune factors and removes bacteria from the bloodstream, contributing to the body’s resistance to infections.
- What is the primary excretory product formed by the liver, and how is it related to the urea cycle?
- Answer: Urea is the primary excretory product formed by the liver. It is produced in the urea cycle, where two ammonia and one CO2 molecules are shunted to generate one molecule of urea.
- What is the function of urea in the body, and how is it detoxified in comparison to ammonia?
- Answer: Urea is a detoxified form of ammonia in the urea cycle. It can be stored in the body in higher amounts than ammonia and can be removed with only 1/10 amount of water compared to ammonia.
- What are the key metabolic pathways associated with the production of urea, and what is the precursor used in the urea cycle?
- Answer: The metabolic pathways associated with urea production are called the urea cycle. Ornithine is the precursor used in the urea cycle.
- How does the liver support the excretory role of the kidney, and what nitrogenous wastes does it produce?
- Answer: The liver detoxifies chemical toxins and produces ammonia, urea, and uric acids from the nitrogen of amino acids, supporting the kidney’s excretory role.
- What categories do the various important functions of the liver fall into?
- Answer: The liver’s functions include synthesis, storage, conversion, recycling, and detoxification, contributing to the body’s homeostasis.
Summary: The Human Liver – Functions & Urea Cycle
The tutorial provides a comprehensive understanding of the human liver, emphasizing its anatomy, functions, and its crucial role in maintaining homeostasis through the urea cycle. The liver, the second-largest organ in the body, serves as a metabolic powerhouse, intricately linked with digestion, absorption, and processing of food.
Key points covered:
- Liver Anatomy: Describes the liver’s location, shape, and vascular nature, highlighting its two primary lobes and their interconnected structure.
- Functions of Liver: Explores the liver’s multifaceted functions, including blood processing, nutrient production, bile secretion, and immune response. Over 500 vital functions are attributed to the liver, showcasing its indispensable role in maintaining overall health.
- Liver in Homeostasis: Positions the liver as the central station of metabolism, vital for homeostasis. It elucidates the liver’s interactions with various organ systems and its critical role in supporting the kidney’s excretory function.
- Urea Cycle: Delves into the urea cycle, elucidating the liver’s detoxification process, where ammonia is converted into urea for safe elimination from the body. The metabolic pathways of the urea cycle are detailed, emphasizing the liver’s efficiency in handling nitrogenous wastes.
- Significance of Liver Functions: Highlights the importance of liver functions in synthesis, storage, conversion, recycling, and detoxification. These categories showcase the liver’s diverse and essential contributions to maintaining a balanced internal environment.
The tutorial serves as a comprehensive guide, offering insights into the intricacies of liver functions and their impact on overall physiological well-being.