In class our teacher, Cecilia Adem, introduced us the last proyect in Biology. This consisted on making a model and explaining all the parts of the urinary sistem or excretory sistem. She also assigned us pairs to work with. I worked with Francisco Aresi. Here it is our proyect:

Parts of the excretory system:

• Kidneys:

They are at the back of the abdomen, behind the intestine.

The kidney is present on each side of the vertebral column in the abdominal cavity. Humans have two kidneys and each kidney is supplied with blood from the renal artery.

The kidneys remove from the blood the nitrogenous  such as urea, as well as salts and excess water, and excrete them in the form of urine. This is done with the help of millions of nephrons present in the kidney.

The urine from the kidney is collected by the ureter, one from each kidney, and is passed to the bladder.

• The bladder:

The bladder collects and stores the urine until urination. The urine collected in the bladder is passed into the external environment from the body through an opening called the urethra.

The bladder is the organ that collects waste excreted by the kidneys prior to disposal by urination. It is an  elastic organ, and sits on the pelvic floor. Urine enters the bladder through the ureters and exits in the urethra.

Urine, excreted by the kidneys, collects in the bladder before disposal by urination. The bladder usually holds 300-350 ml of urine. The bladder stores larger amounts of urine without a significant rise in internal pressure.

• Interior vena cava:

The inferior vena cava is the largest vein in the human body. It collects blood from veins serving the tissues inferior to the heart and returns this blood to the right atrium of the heart. Although the vena cava is large.
The inferior vena cava forms at the superior end of the pelvic cavity when the common iliac veins unite to form a larger vein. From the pelvis, the inferior vena cava ascends through the posterior abdominal body wall just to the right of the vertebral column.

• Ureters:

The ureter is a tube that carries urine from the kidney to the urinary bladder. There are two ureters, one attached to each kidney. The upper half of the ureter is located in the abdomen and the lower half is located in the pelvic area. The tube has thick walls composed of a fibrous, a muscular, and a mucus coat, which are able to contract

• Renal Veins:

The renal veins are veins that drain the kidney. They connect the inferior vena cava to the kidney. They carry the blood filtered by the kidney.There are two renal veins, a left and a right. As they enter the kidneys, each vein separates into two parts. The posterior veins assist in draining the back section of each kidney, while the anterior veins assist the front part. These veins also are responsible for draining blood from the ureter, which transports urine away from the kidneys to the urinary bladder.

• Renal arteries:

The renal arteries arise off the side of the abdominal aorta, below the superior mesenteric artery, and supply the kidneys with blood. Each is directed across the crus of the diaphragm, so as to form nearly a right angle with the aorta. The renal arteries carry blood flow to the kidneys. Up to a third of total cardiac output can pass through the renal arteries to be filtered by the kidneys.

• Urethra:

The urethra is the tube through which urine passes from the bladder to the exterior of the body. The female urethra is around 2 inches long and ends inferior to the clitoris and superior to the vaginal opening. In males, the urethra is around 8 to 10 inches long and ends at the tip of the penis. The urethra is also an organ of the male reproductive system as it carries sperm out of the body through the penis.

Besides, the urethra is a tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body.

• Dorsal Aorta:

The abdominal aorta is about an inch in diameter and extends along the entire length of the abdomen, from the diaphragm to the pelvis. It enters the abdomen through a small opening at the posterior end of the diaphragm, just anterior to the spinal column. From this point, it descends along the spine parallel to the inferior vena cava until it reaches the pelvis, where it divides into the right and left common iliac arteries.

Many major arteries branch from the abdominal aorta to provide blood flow to the vital organs of the abdomen. Its visceral branches provide blood to organs, while its parietal branches supply blood to the tissues of the abdominal body wall.

• Adrenal gland:

You have two adrenal glands. They’re located on top of each of your kidneys. They  produce hormones.

While they’re small in size, the adrenal glands are responsible for  hormone-related functions in your body. As a result, disorders that affect your adrenal glands can have a broad impact on your health.

How we make the model:

To make the model, we used a pair of headphones to represent both kidneys which have wires that we used to represent the ureter. Also, on the kidneys,  we used telgopor to make the adrenal gland. Later, we found contact paper, that we cut it to make the vena cava. The same with the dorsal aorta, which is blue fabric. Finally, to create the urinary bladder, we bought a can of “Coca-Cola”  that we wrapped in red contact paper. Also, we cut red contact paper to create the urethra.