The Human Excretory System

Contents of the presentation

• Different parts of the human excretory system

• What are kidneys ? What are their functions ?

• What is haemodialysis ?

• Kidney failure

• The different types of kidney diseases

What are the different parts of the human excretory system

The human excretory system is made up of :

a) A pair of kidneys

b) A pair of ureters

c) Urinary bladder

d) Urethra

What are kidneys ? What are their functions ?

• The kidneys are bean shaped organs that remove excess organic molecules produced by the different metabolic activities in the human body.

• Kidneys are essential for maintaining the electrolytes in our body and maintain the pH of the blood and for the regulation of blood pressure (by maintaining the salt and water balance in the body)

• Kidneys serve as the natural filters of the blood and remove water soluble wastes which are diverted to the urinary bladder . In producing urine kidneys remove wastes like amino acids , glucose and other substances which are again reabsorbed

What are kidneys what are their functions

• The kidneys produce different hormones to remove the wastes these are Calcitriol , erythropoietin.

• The kidneys are located on the rear of the abdominal cavity. The kidneys receive blood from paired renal arteries which drain into the nephrons

• The nephrons are the basic functional unit of the kidneys. The renal artery form capillaries and drain into the glomerulus a cup shaped structure of the nephron and travel through the ureters to the urinary bladder and is released as urine .

Basic functional units of kidneys

About the nephrons

NEPHROS is the Greek word for kidney. The tiny structures that do the work in your kidneys are called NEPHRONS. Each of your kidneys contains about one million nephrons. Each nephron has a small blood vessel that brings in unfiltered blood, a GLOMERULUS (glow-mare-Yule-us) that filters the blood, a tubule that caries away filtered waste materials in the urine, and a small blood vessel that returns filtered blood to the body.

The Glomerulus

About the glomerulus

A glomerulus is a network of capillaries located at the beginning of a nephron in the kidney. It serves as the first stage in the filtering process of the blood carried out by the nephron in its formation of urine

The glomerulus is surrounded by a cup-like sac known as Bowman’s capsule. The blood plasma is filtered through the capillaries of the glomerulus into the capsule. The Bowman's capsule empties the filtrate into the proximal tubule that is also part of the nephron.

What is haemodialysis ?

• Haemodialysis is the process of removing nitrogenous wastes as well as free water from the body from the blood artificially using a machine called dialyser. Modern dialyzers typically consist of a cylindrical rigid casing enclosing hollow fibers cast or extruded from a polymer or copolymer, which is usually a proprietary formulation. The combined area of the hollow fibers is typically between 1-2 square meters. Intensive research has been conducted by many groups to optimize blood and dialysate flows within the dialyzer, in order to achieve efficient transfer of wastes from blood to dialysate.

Kidney failure and kidney diseases

• Kidneys are paired vital organs located behind the abdominal cavity, at about the level of the bottom of the ribcage. They perform about a dozen physiologic functions, and are fairly easily damaged. Kidney failure results in the slow accumulation of nitrogenous wastes, salts, water, and disruption of the body's normal pH balance. Until the Second World War, kidney failure generally meant death for the patient.

• The accumulation of the wastes converts it into neurotoxins. These neurotoxins damage the nervous system leading to the person’s death.

Different types of kidney failures

• Kidney disease, also known as Nephropathy, means damage to or disease of a kidney. Nephrosis is non-inflammatory nephropathy. Nephritis is inflammatory kidney disease.

• There are mainly 3 types of kidney failures presented in the presentation:

a) Deposition of the IgA antibodies in the glomerulus

b) Administration of analgesics

c) Toxicity of Chemotherapy Agents

Kidney failure due to deposition of IgA antibodies in glomerulus

• Immunoglobulin A (IgA) is an antibody that plays a critical role in mucosal immunity. More IgA is produced in mucosal linings than all other types of antibody combined between three and five grams are secreted into the intestinal lumen each day. This accumulates up to 15% of the total immunoglobulin produced in the entire body. 

• IgA nephropathy is the most common glomerulonephritis throughout the world Primary IgA nephropathy is characterized by deposition of the IgA antibody in the glomerulus. The classic presentation (in 40-50% of the cases). Less commonly gastrointestinal or urinary infection can be the inciting agent. All of these infections have in common the activation of mucosal defenses and hence IgA antibody production. which get deposited in the glomerulus and result in kidney failure.

Kidney failure due to administration of analgesics

• One cause of nephropathy is the long term usage of analgesics. The pain medicines which can cause kidney problems include aspirin, acetaminophen, and nonsteroidal anti-inflammatory drugs, or NSAIDs. This form of nephropathy is "chronic analgesic nephritis," a chronic inflammatory change characterized.

• The basic symptoms of kidney failures are nausea, vomiting , loss of appetite, fatigue and weakness, sleep problems , changes in urine output decreased mental sharpness, muscle twitches and cramps.

Kidney failure due to toxicity of chemotherapy agents

• Kidney failure Nephropathy can be associated with some therapies used to treat cancer. The most common form of kidney disease in cancer patients is Acute Kidney Injury (AKI) which can usually be due to volume depletion from vomiting and diarrhea that occur following chemotherapy or occasionally due to kidney toxicities of chemotherapeutic agents. Kidney failure from break down of cancer cells, usually after chemotherapy, is unique. Several chemotherapeutic agents, for example Cisplatin, are associated with acute and chronic kidney injuries. Newer agents such as anti Vascular Endothelial Growth Factor (anti VEGF) are also associated with similar injuries

Created by Ashwin , Anantha , Akshay

Karanth and Anirudh