Category: Biology Second Paper Lecture Sheet

The tube that originates from the pelvis and opens into the urinary bladder is called the ureter. Its length is about 25-30 cm. It carries urine from the kidneys to the bladder.

Kidney looks like a bean seed. Its outer side is convex and inner side is concave. Below the ribcage in the lumbar region of the abdominal cavity are two kidneys on either side of the spine. The left kidney is slightly larger than the right kidney. The upper edge of the kidney lies below the 12th thoracic vertebra and is protected by the 11th and 12th vertebrae. The lower edge of the kidney lies above the third lumbar vertebra. The left kidney lies slightly above the liver and the right kidney slightly below.

The system through which nitrogenous wastes are excreted from the body is called the excretory system. Different parts of excretory system are-
1. Kidney: Kidney looks like a bean seed. Its outer side is convex and inner side is concave. Below the ribcage in the lumbar region of the abdominal cavity are two kidneys on either side of the spine. The left kidney is slightly larger than the right kidney. The upper edge of the kidney lies below the 12th thoracic vertebra and is protected by the 11th and 12th vertebrae. The lower edge of the kidney lies above the third lumbar vertebra. The left kidney lies slightly above the liver and the right kidney slightly below.
2. Ureter: The tube that originates from the pelvis and opens into the urinary bladder is called the ureter. Its length is about 25-30 cm. It carries urine from the kidneys to the bladder.3. Urinary bladder: Urinary bladder is a triangular sac. Its wall is thin, elastic and composed of involuntary muscles called detrusors. It acts as a urinary reservoir. The bladder can hold 700-750 ml of urine. However, only when 280-320 ml of urine accumulates, the urge to urinate arises. Patients with hyperuricosuria develop stones in the urinary bladder.
4. Urethra: The narrow tube behind the urinary bladder is called the urethra. The length of the urethra is 18-20 cm in males and 3.5-4.0 cm in females. Urine is released through it.

1. It is more complex and harmful.
2. It is a nitrogenous substance.
3. It is excreted through the excretory system.
4. It is not stored in the body.
5. It is not reused in the animal body.

The process by which nitrogenous waste products are regularly removed from the body is called excretion. Nitrogenous waste products are called excreta. The main excretory substances of the human body are urea, uric acid, ammonia, creatinine etc.

During the production of amino acid energy in the human body, some nitrogenous toxic waste products are produced. The main nitrogenous waste product of humans is urine. The main excretory organ is kidney. Kidney is called the master chemist of the body. 80% of excreta are excreted through the kidneys. The remaining 20% of the excreta is excreted through the accessory excretory organs. The auxiliary excretory organs in the human body are the skin, lungs, liver and digestive tract. The branch of biology that deals with the structure, function and diseases of kidney is called Nephrology.

Pteri absorb large amounts of arsenic from the soil. So it can be used to treat depression caused by arsenic.

Molecules of Lycopodium burn and emit colorful light. Hence it is called flint plant. Flint plant is used to make fireworks.

Ferns can be used to produce essential chemicals. Potash is obtained from Dryopteris and silicon from Equisetum. Potash is used to make soap and glass.

Fern plants are used in various events, home decoration, garden beautification etc. Lycopodium obscurum, also known as Christmas green, is used as a beautifier in Christmas celebrations. Lycopodium, Selaginella etc. are used for decoration.