Urinary System Structure and Functions

Science V

What are the parts of the urinary system?

What are the parts of the kidney?

Review

Checking of Assignment

Answer the following question:1. How can you take good care of our

urinary system?2. What foods are good to the urinary

system?3. Why are salty foods not good to eat?

Motivation

• What is the shape of the kidney? • Where are the kidneys located?• Would you like to find out about their

structure and function/s?

Presentation

Watch the video clipExcretory System Parts and Functions

Animation video for kids

The kidneys are two bean-shaped organs about the size of a clenched fist.Can you point where the kidneys are?

Concept Formation

Each kidney is divided into three regions.

The outermost region is the

Cortex

The middle region is the

Medulla

which consists of collecting ducts that

carry the urine

The inner region is the

Pelvis

a cavity connected to the ureter, into which the urine

drains

The

Renal Artery

delivers oxygenated blood to the kidney

The

Renal Vein

receives deoxygenated blood from the peritubular

veins within the kidney

Their vital functions include:• Removal of extra water and waste products

from the blood in the form of urine.• Keeping a stable balance of salts and other

substances in the body.• Releasing hormones that help maintain the

normal number of red blood cells and regulate blood pressure.

Concept Formation

Interesting fact:

The right kidney is slightly lower than the left because the liver displaces it downward.

Concept Formation

Concept Formation

The functional and structural units of the kidneys are the nephrons. Each kidney contains about 1.25 million nephrons.

Concept Formation

Each nephron consists of two parts: a cup shaped structure called the Bowman’s capsule and a network of tubules.

Proximaltubule

Concept FormationThe Bowman’s capsule encloses a bundle of tiny capillaries called the glomerulus—where actual sifting or filtering of blood occurs. Connected to the Bowman’s capsule are the network of convulated tubules divided into four kinds.

Concept FormationThe Proximal convulated tubules, the Henle’s loop, the distal convulated tubule, and the collecting tubule. The collecting tubule receives the nitrogen waste from many nephrons.

Concept Formation

Impure blood enters the kidney through the renal artery.Purified blood exits the kidneys through the renal vein.

Concept Formation At first, the tubules receive a combination of waste materials and chemicals that your body can still use. Some of these chemicals include sodium, phosphorus, and potassium. If your body is lacking any of these chemicals, your kidneys can release them back to the blood to maintain their normal levels. If these chemicals are in excess, the kidneys will release it to become a part of the urine.

Concept FormationThis is how the kidneys maintain the normal levels of chemicals inside your body. The right balance is necessary for life, but excess levels can be harmful too.

If the kidneys fail to function, a condition called renal failure, this would cause an excessive build up of toxins in the body. You will need dialysis to rid of these toxins.

Concept FormationThe kidneys also release important hormones that help to maintain balance in the body.Erythropoietin (eh-RITH-ro-POY-eh-tin) or EPO, stimulates the bone marrow to make red blood cellsRenin (REE-nin) regulates blood pressureCalcitriol (kal-suh-TRY-ul), the active form of vitamin D, helps maintain calcium for bones and for normal chemical balance in the body

Each kidney has a drainage tube called ureter. The walls of the ureter have a thick layer of smooth muscle which contracts. The contraction of the muscle in the ureter move urine to the bladder.Can you point where the ureters are?

Concept Formation

Constant tightening and relaxing of muscles in the ureter wall forces urine downward away from the kidneys. These muscles help to maintain a one-way flow of urine from the kidneys to the bladder. If urine is allowed to stand still, or to flow back into the kidneys, a kidney infection may develop.

Concept Formation

The urinary bladder is a balloon-shaped, hollow, muscular sac inside the pelvis (hip bones). It is held in place by ligaments attached to other organs and the pelvic bones.

Concept Formation

The bladder stores urine until it is released when you urinate. As urine flows into the bladder, it becomes larger and the shape becomes more rounded or spherical. When it is empty, its size becomes smaller. Small amounts of urine are emptied into the bladder from the ureters about every 10 to 15 seconds.

Concept Formation

A normal adult bladder can store up to 2 cups of urine for as long as 2 to 5 hours.

Concept Formation

Sphincter muscles are two circular muscles around the opening of the bladder into the urethra. They help keep urine from leaking into the urethra.

Concept Formation

Concept Formation

The urethra is the tube that allows urine to pass outside the body. The urethra has a ring of skeletal muscle around its opening. The male and female urethra are different in some ways.

Concept Formation

In females, their urethra are much shorter than in males. In addition to urine, the male urethra is also where semen passes through.

Application

Your mother sent you to the market to buy a cow's kidney. Would you be able to buy a cow's kidney by pointing the kidney to the meat vendor? Can you tell the function of the kidney?

Evaluation

Choose the letter of the correct answer:1. What carries waste from the kidney to the bladder?

a. Urethra c. Cortexb. Ureter d. Medulla

2. What protects the kidney?a. Nephron c. Cortexb. Ureter d. Medulla

Evaluation3. Which of the following are the filter devices of the kidneys?

a. Nephron c. Ureterb. Glomerulus d. Cortex

4. What is the cuplike structure of the nephon called?

a. Pelvis c. Urethrab. Glomerulus d. Bowman’s

capsule

Evaluation5. What kind of blood is in the renal artery?

a. Clean c. Purifiedb. Unclean d. Sometimes

clean

Key

1. b 2. c3. b4. d5. c

Assignment

1. Do most people have two (2) kidneys?2. Can a person live normally with only one kidney?3. What is the function of the kidney?4. What part of the urinary system stores urine?