Human Excretory System
The human body is complex and operates with the help of multiple organ systems like digestive system, circulatory system, respiratory system etc. that work non-stop simultaneously. They ensure a state of steady internal, physical and chemical conditions i.e. homeostasis and viability of the human body. These life processes release waste products into the blood. The excretory system helps in eliminating these waste products that could be toxic to the body by filtering the blood.
Its parts are:
- SKIN: The skin excretes sweat and eliminates salts and some amount of urea.
- LUNGS: They are a part of the respiratory system and help to eliminate carbon dioxide and water vapor produced during metabolism.
- THE URINARY SYSTEM: The function of the Urinary System is to filter blood and create urine so as to remove the waste products like urea, uric acid, excess salts and minerals from the body.
- LIVER: It detoxifies and purifies blood and helps in the excretion of bilirubin, cholesterol, hormones and drugs.
Human Urinary System
The body takes nutrients from food and converts them into energy and other by products. After the body has taken the necessary nutrients from food, waste products are left behind in the bowel and in the blood.
The purpose of the URINARY SYSTEM is to eliminate waste from the blood, regulate blood volume and blood pressure, and control the levels of electrolytes and metabolites in it. The organs of the urinary system include the kidneys, ureters, urinary bladder, urethra and urinary opening.
This pair of purplish-brown organs is located below the ribs toward the middle of the back. The kidneys help the body to eliminate wastes called urea, which is produced when foods containing protein, such as meat, poultry, and certain vegetables, are broken down in the body. Urea is carried in the bloodstream to the kidneys, where it is removed along with water, uric acid, salts and minerals– such as potassium and sodium in the form of urine.
Some Parts of the Kidney:
- Renal artery and Renal Vein: The renal artery supplies the kidney with blood. The renal vein, on the other hand, carries the blood filtered by the kidney.
- Nephrons: The kidneys remove urea from the blood through tiny filtering units called nephrons. Each nephron consists of a cluster of tiny blood capillaries, called a glomerulus, and a small tube called a renal tubule. The blood is filtered across the capillary walls and the filtrate is sent to the renal tubule.
URETERS: These tubes carry urine from the kidneys to the urinary bladder. Muscles in the ureter walls continuously contract and relax like waves pushing the urine in downward direction, towards the bladder. An obstruction in ureters may lead to fever, kidney infections, sepsis and even death.
URINARY BLADDER: Located in the lower abdomen, urinary bladder is a triangle-shaped, hollow organ held in place by ligaments that are attached to other organs and the pelvic bones. The walls of the bladder can relax and expand in order to store urine, and contract and compress to empty urine through the urethra. A typical healthy adult bladder can store up to 400-600 mL urine.
- Sphincter muscles: These pair of muscles controls the exit of urine from the urinary bladder through the urethra. When either of them contracts, the urethra is sealed shut. When it relaxes, the urethra opens up.
- Nerves in the bladder: The nerves send a signal to the brain and alert a person when it is time to empty the bladder.
URETHRA: This thin tube at the lower opening of the bladder allows urine to pass outside the body. Once the brain receives a signal to empty the bladder, it leads to a chain reaction that includes contraction of the bladder muscles, relaxation of the sphincter muscle followed by opening of the urethra.
URINARY OPENING: It is the opening of the urethra where urine exits the body.
Disorders Related to the Urinary System
Common diseases that affect the Urinary System:
Common diseases of the urinary system include kidney stones, kidney failure, and urinary tract infections.
Causes: Kidney stones are formed when minerals form tiny hard clumps in the kidneys. It becomes painful to remove them and may block the urine flow. The main causes of kidney failure in the United States are Type 2 Diabetes and high blood pressure. Urinary tract infections or UTIs are infections in any part of the urinary system. The most common causes of UTIs are bacterial infections. Females are more susceptible to UTIs due to their shorter urethras.
Symptoms: Common symptoms include a strong frequent urge to urinate and burning sensation while urinating.
Prevention: Adequate intake of water, a balanced diet and a healthy lifestyle can keep these diseases away. For 9-12 years old kids, the recommended daily amount of fluid is 7 glasses or 1.5 L.
The normal range of urine production in adult humans is 0.6 to 2.6 L with 6-8 urinations per day. However, it depends on the level of hydration in the person’s body, the person’s size, weight, health, activities, and environmental factors. Normal, healthy urine is a pale straw or transparent yellow in color. Darker yellow or honey-colored urine means that our body needs more water.
Thus, the excretory system is a passive biological system that removes excess, unwanted materials from the body fluids of an organism. Any failure in the excretory system would result in internal chemical disturbances with wastes accumulating in our body leading to damage inside it.
- The skin excretes water and excess salts by ____________.
- The waste material formed by protein rich diet is __________.
- The filtration of blood takes place in the nephrons present inside the __________.
- The walls of the ________ can relax and expand in order to store urine.
- The two main causes of kidney failure in the United States are Type 2 diabetes and _________.
- Urinary Bladder
- High Blood Pressure