Main Difference – Liver vs Kidney
Liver and kidney are two vital organs in the body of animals. Liver is the second largest internal organ of the body. It is found on the right-hand side of the belly. Kidneys are two bean-shaped organs, which are located below the rib cage on either side of the spine. The main difference between liver and kidney is that liver is involved in the synthesis of proteins, glycogen, triglycerides, cholesterol, and bile whereas kidney removes waste products and excess fluid from the body. Liver is also involved in the breakdown of food, cleaning of the blood, and storage of energy. Kidney regulates the salt, potassium, and acid content of the body. It also serves as an endocrine organ by producing hormones.
Key Areas Covered
1. What is Liver
– Definition, Anatomy, Physiology
2. What is Kidney
– Definition, Anatomy, Physiology
3. What are the Similarities Between Liver and Kidney
– Outline of Common Features
4. What is the Difference Between Liver and Kidney
– Comparison of Key Differences
Key Terms: Digestion, Excretion, Homeostasis, Kidney, Liver, Lobules, Metabolism, Nephron, Storage
What is Liver
Liver is a large lobed, glandular organ in the abdomen of vertebrates. It performs functions related to digestion, metabolism, storage, and immunity of the body. It is located just below the diaphragm, and most of the liver mass is localized into the right side of the abdomen. Liver is made up of soft, pinkish-brown tissue and is encapsulated by a connective tissue capsule, which is further reinforced by the peritoneum. The four lobes of the liver are the left, right, caudate, and quadrate lobes. The largest lobes are the left and right lobes. They are separated by the falciform ligament. The anatomy of the liver is shown in figure 1.
Figure 1: Liver
The microscopic structure of the liver is made up of around 100,000 hexagonal functional units called lobules. There is a central vein in the middle of each lobule, and this central vein is connected to the hepatic vein. Each lobule is also surrounded by six hepatic arteries, six hepatic portal veins, and six bile ducts. Capillary-like tubes are extended from hepatic arteries and portal veins to the central vein. These capillary-like tubes are called sinusoids. Sinusoids are surrounded by hepatocytes and Kupffer cells. The microscopic anatomy of the liver is shown in figure 2.
Figure 2: Microscopic Anatomy of the Liver
Hepatocytes are the majority of liver cells. They perform the functions of the liver such as digestion, metabolism, storage, bile production. Kupffer cells capture old and worn out red blood cells and break them down.
What is Kidney
Kidney refers to each pair of organs in the abdominal cavity of mammals, birds, and reptiles, which excrete urine. Two kidneys can be identified along the posterior muscular wall of the abdominal cavity. They lie behind the peritoneum. Renal capsule, renal cortex, and renal medulla are the three zones of the kidney. Renal medulla is composed of around seven renal pyramids; their bases face towards the renal cortex, and the apexes face towards the center of the kidney. Each apex connects to a minor calyx. Each calyx opens to the renal pelvis. The anatomy of the kidney is shown in figure 3.
Figure 3: Kidney
The nephron is the functional unit of the kidney, which is responsible for the filtering of blood. A single kidney may contain around 1 million nephrons. The renal corpuscle and the renal tubule are the two components of a nephron. A renal corpuscle is made up of the Bowman’s capsule and the capillaries of the glomerulus. The Bowman’s capsule is made up of a special type of epithelial cells called podocytes. Proximal convoluted tubule, loop of Henle, distal convoluted tubule, and the collecting duct are the capillaries of a nephron. The anatomy of a nephron is shown in figure 4.
Figure 4: A nephron
Filtration, reabsorption, and secretion are the three functions of the nephron. The final product of a nephron is called urine, which contains urea. Water homeostasis, acid/base homeostasis, electrolyte homeostasis, and blood pressure homeostasis are the major regulatory functions of the kidney. Calcitriol and erythropoietin are the two hormones produced by the kidney. Calcitriol increases the absorption of calcium in the intestinal tubule. Erythropoietin stimulates the bone marrow to produce red blood cells.
Similarities Between Liver and Kidney
- Both liver and kidney are vital organs of the animal body.
- Both liver and kidney are involved in the excretion of substances from the body.
Difference Between Liver and Kidney
Definition
Liver: Liver refers to a large lobed, glandular organ in the abdomen of vertebrates, which is involved in metabolism.
Kidney: Kidney refers to each pair of organs in the abdominal cavity of mammals, birds, and reptiles, which excrete urine.
Location
Liver: Liver is located in the upper right portion of the abdominal cavity, just below the diaphragm.
Kidney: Kidney is located below the rib cage, on either side of the spine.
Peritoneum
Liver: Liver is attached to the peritoneum.
Kidney: Kidney lies behind the peritoneum.
Significance
Liver: Liver is the second largest internal organs as well as the largest gland in the body.
Kidney: Kidney is a very complex organ, which is made up of thousands of nephrons.
System
Liver: Liver belongs to the digestive system of the body.
Kidney: Kidney belongs to the urinary system of the body.
Number
Liver: There is only one liver in the body.
Kidney: There are two kidneys in the body.
Function
Liver: The major function of the liver is the metabolism of carbohydrates, lipids, and proteins.
Kidney: The major function of the kidney is the excretion of wastes and regulation of osmolality.
Other Functions
Liver: Production of bile and clotting factors are the other functions of the liver.
Kidney: Hormone secretion, blood pressure regulation, and maintenance of the body pH are the other functions of the kidney.
Excretion
Liver: Liver excretes metabolic wastes from the hemoglobin breakdown as bile pigments.
Kidney: Kidney excretes ammonia, urea, uric acid, urochrome, water, and certain inorganic irons.
Storage
Liver: Liver stores glycogen, fat, ions, and vitamins.
Kidney: Kidney does not store any substances.
Conclusion
Liver and kidney are two vital organs of the animal body. Liver is mainly involved in the metabolism of carbohydrates, proteins, and lipids. It also stores nutrients. Kidney is the major excretory organ of the body. The main difference between liver and kidney is the function of each organ in the body.
Reference:
1.“Liver.” InnerBody, Available here.
2.“Kidneys.” InnerBody, Available here.
Image Courtesy:
1. “Gray1086-liver” By Henry Vandyke Carter – Henry Gray (1918) Anatomy of the Human Body, Bartleby.com: Gray’s Anatomy, Plate 1086 (Public Domain) via Commons Wikimedia
2. “2423 Microscopic Anatomy of Liver” By OpenStax College – Anatomy & Physiology, Connexions Web site. Jun 19, 2013 (CC BY 3.0) via Commons Wikimedia
3. “2610 The Kidney” By OpenStax College – Anatomy & Physiology, Connexions Web site, Jun 19, 2013 (CC BY 3.0) via Commons Wikimedia
4. “Anatomy and physiology of animals Kidney tubule or nephron” By The original uploader was Sunshineconnelly at English Wikibooks – Transferred from en.wikibooks to Commons by Adrignola using CommonsHelper (CC BY 3.0) via Commons Wikimedia
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