The Urinary System

Functions of the Urinary Functions of the Urinary system:system:

1. Removes salts and nitrogenous wastes

2. Maintains normal amounts of water and electrolytes

3. Regulates the pH level and volume of fluids.

4. Helps control red blood

cell production and blood

pressure.

The organs of the Urinary The organs of the Urinary System:System:

1. The Kidney (2 of them) • And all of the accessory organs with the kidney

2. A pair of ureters (tube structures)

3. Urinary bladder

4. Urethra (tube structure)

They KidneyThey Kidney• Reddish brown bean shaped

organ that is smooth.

• They lie on both sides of the vertebral column on the upper posterior wall of the abdominal.

• The kidney attaches to blood vessels and lymphatic vessels from the cardiovascular system at the renal pelvis.

They KidneyThey Kidney

The role of the kidney: The role of the kidney: 1. Helps maintain homeostasis by removing

wastes from the blood and combining them with excess water and electrolytes to form urine which eventually gets excreted.

2. Help control the rate of red blood cell production through a hormone they secrete.

3. Help maintain blood pressure 4. Play a role in the activation

of Vitamin D

• Lined with blood vessels.

• Recieves oxygenated blood through the Abdominal Aorta. This branches to interlobar interlobar arteriolesarterioles, and finally small capillaries called glomerulusglomerulus located on the nephronnephron (where urine is formed and processed).

• Deoxygenated blood leaves the kidneys through the Inferior Vena Cave to be returned to the heart.

The role of the kidney: The role of the kidney:

The UretersThe Ureters1. A tube about 25cm long

2. Begins at the renal pelvis of the kidney and runs parallel to the vertebral column on each side until it reaches the urinary bladder.

3. Made up of mucous lining, smooth muscle and connective tissue.

4. What do you think the smooth muscle does?

Correct- they propel the urine to your bladder!Correct- they propel the urine to your bladder!The UretersThe Ureters

1. Your ureters have a valve just like the heart to prevent the flow of urine back through the ureters.

2. This valve called: ureteral mucous ureteral mucous openingopening, opens when urine is pushed against it and closes when urine reaches the bladder.

The BladderThe Bladder1. A hallow, muscular organ, spherical shape, very

flexible, located in the pelvic cavity.

2. It is made up of smooth muscle, connective tissue and epithelial tissue.

3. IT IS VERY FLEXIBLE and can stretch and change shape depending on how much urine is inside.

• At the triangular portion it attaches to the urethra tube. Label the structure of the bladder:

The BladderThe Bladder

• What is the difference between the Internal urethral What is the difference between the Internal urethral sphincter and the external urethral sphincter?sphincter and the external urethral sphincter?– The internal urethral sphincter is a smooth muscle. Which

means what? – Does it automatically. You can not control when urine wants

to leave the bladder. – The external is a skeletal muscle. You can control though if

you release urine from the urethra. – You are able to “hold it” like when I don’t give you a pass to

the bathroom- your external urethral sphincter muscles are working.

The BladderThe Bladder

The UrethraThe Urethra1. The tube that transports urine from the

urinary bladder to outside the body.

2. Contains glands that secrete mucous into the tube to help urine pass.

URINE FORMATION: The URINE FORMATION: The NephronNephron

Figure 3. Urine formation takes place in the nephron (Functional unit of the kidney).

Structure of the Nephron: Structure of the Nephron:

Urine production• Urine formation begins with the process of

filtration of blood.

• As blood flows through the glomeruli (capillaries), waste and chemicals, soak out of the blood through the membranes (by osmosis and diffusion) where it is filtered and then continues flowing down the nephron.

• Water, excess salts (primarily Na+ and K+), glucose, and waste products of the body are called urea

• Urea is formed in the body to eliminate toxic ammonia products that are formed in the liver from amino acids

WHAT IS EXCRETED???WHAT IS EXCRETED???•About 125 ml of water and dissolved substances are filtered out of the blood per minute.

After waste or water is excreted, it can also be REABSORBED. REABSORBED. •Reabsorption, by definition, is the movement of substances out of the blood into the renal tubules then back into the blood capillaries located around the tubules •Substances reabsorbed are water, glucose and other nutrients, and sodium (Na+) and other ions

• The pathway of urine: From the capillaries to the bowman’s capsule next goes in the proximal convoluted tubules and continues in the loop of Henle, distal convoluted tubules, and collecting tubules

• Substances secreted and removed are hydrogen ions (H+), potassium ions (K+), ammonia (NH3), and certain drugs

• Kidney tubule secretion plays a crucial role in maintaining the body's acid-base balance, another important body function that the kidney participates in.

Control of Urine ProductionControl of Urine Production

• Urine is produced not only in order to eliminate many of the cellular waste products, but also to control both the amount and the composition of the extracellular fluid in the body

• The kidney tubule regulation of the salt and water in our bodies is the most important factor in determining urine volume.

• The level of water and salts excreted in The level of water and salts excreted in urine - urine - the urine volume the urine volume - is adjusted to - is adjusted to the needs of the body. the needs of the body.

• As a general rule, however, and under As a general rule, however, and under optimum conditions, the body produces optimum conditions, the body produces urine at a rate of about 1 ml/min. urine at a rate of about 1 ml/min.

• Controlled by hormones, chemical messengers that travel through the blood system and act as regulators of many of the body's internal activities

Control of Urine Volume through ADH (anti-diuretic hormone )

• Urine is controlled by a hormone called the Anti-diuretic hormone.

• This hormone inhibits urine formation.

• The sodium concentration in the fluid is the factor that either stimulates the release ADH or to inhibit the release of ADH

• When a person drinks an excess of water, the sodium in the body fluids, including the blood becomes more dilute and the release of ADH is inhibited.

• When the sodium level is high in the fluid the ADH is stimulated which means it will inhibit urine formation. Since the salt content is too high your body needs to retain it’s water to balance it out.

Figure 5. The regulation of body water and sodium ion (Na+) concentration in the blood is controlled through the release of anti-diuretic hormone (ADH). This system operates using a negative feedback loop.