The Urinary System

The Urinary System

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

1. Removes salts and nitrogenous wastes2. 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

• Let’s label the parts of the kidney!They KidneyThey Kidney

Answer Key: Kidney Label1.1. Renal pyramidRenal pyramid2.2. Interlobar arteryInterlobar artery3.3. Renal arteryRenal artery4.4. Renal veinRenal vein5.5. Renal hylumRenal hylum6.6. Renal pelvisRenal pelvis7.7. UreterUreter8.8. Minor calyxMinor calyx

9.9. Renal capsuleRenal capsule10.10. Inferior renal capsuleInferior renal capsule11.11.Superior renal capsuleSuperior renal capsule12.12. Interlobar veinInterlobar vein13.13.NephronNephron14.14.Minor calyxMinor calyx15.15.Major calyxMajor calyx16.16.Renal papillaRenal papilla17.17.Renal columnRenal column

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 long2. 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. Do you remember what type of tissues it is made

up of? – Transitional Epithelium Tissue!!

3. It is also made up of smooth muscle, mucous membranes, and connective tissues (elastic).

• 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, which goes on continually in the renal corpuscles

• As blood flows through the glomeruli (capillaries), much of its fluid, containing both useful chemicals and waste materials, soaks out of the blood through the membranes (by osmosis and diffusion) where it is filtered and then flows into the Bowman's capsule (The next spot on the nephron).

• This process is called glomerular filtration. • 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: Excretion and reabsorption 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 - the urine volume - is adjusted to urine - the urine volume - is adjusted to the needs of the body. As a general the needs of the body. As a general rule, however, and under optimum rule, however, and under optimum conditions, the body produces urine at conditions, the body produces urine at a rate of about 1 ml/min. 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 )

• Diuretic is a substance that acts to increase urine production

• feeling "bloated" = retaining water • An anti- diuretic, on the other hand, is a

chemical that inhibits urine formation• ADH produces its anti-diuretic effect by

acting on the kidneys and causing them to reduce the amount of water they excrete

• ADH is important in regulating the water concentration of body fluids, which ultimately helps to maintain an appropriate sodium concentration in the body

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

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.

• For this reason, ADH is described as the "water-retaining hormone." You might also think of it as the "urine-decreasing hormone."

• 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.

• The kidneys excrete more watery urine until the water concentration of the body fluids returns to normal