Human Excretory and Respiratory System Functions

The Excretory System

The excretory system is responsible for removing toxic substances and waste from our body. The excretory system consists of the urinary tract, lungs, and skin. The system is formed by the kidneys and the urinary tract.

The Urinary System

Function: It is responsible for ridding the body of harmful substances that form in the cells and helps maintain blood alkalinity.

Structure: It is formed essentially of two kidneys that drain their contents into a receptacle called the bladder. The bladder, in turn, empties its contents to the outside through a tube called the urethra.

The Kidneys

The kidneys are two bean-shaped, brown organs located on both sides of the body below the waist. Through the renal artery, blood carrying waste substances reaches the kidneys. Within the kidneys, blood moves through a vast network of tiny capillaries that act as filters; debris carried by the blood is retained in the kidney and urine is formed.

Urine is a yellowish liquid consisting of water, minerals, and substances toxic to the body, such as urea and uric acid. After formation, urine passes through the urinary tract. The urinary tract includes the ureters, bladder, and urethra. The blood leaves the kidney via the renal vein. It no longer contains urea or uric acid, but it still carries carbon dioxide. It then passes to the vena cava and finally goes to the heart and then the lungs.

Parts of the Kidney

• The renal capsule
• The cortical area
• The core area
• The renal pelvis
• Urethral meatus

The Respiratory Apparatus

Function: To supply oxygen to the body, mainly the brain.

Constitution: It consists of three main parts:

Respiratory Passages

• The nostrils: Two cavities located above the mouth.
• Pharynx: A passage through which the food we eat and the air we breathe pass.
• Larynx: Contains the vocal cords that vibrate so the voice occurs.
• The trachea: A tube of 12 cm in length located in front of the esophagus.
• Bronchi: Tubes into which the trachea is divided as it enters the lungs, where they branch multiple times.

The Lungs

The bronchi lead into the lungs. The right lung has three lobes and the left lung has two, with a gap for the heart. The lobes are divided into smaller sections, and these in turn into even smaller ones. A membrane surrounds the lungs to protect them from the ribs.

Process of Inspiration and Expiration

• Inspiration: When the diaphragm contracts, the chest cavity expands and air enters the lungs rapidly through the windpipe to fill the resulting vacuum.
• Expiration: When the diaphragm relaxes, it adopts its natural curved upward position; then the lungs contract and air is expelled.