Excretory and Urinary System Notes Chapter 15. Functions of the Urinary System Slide 15.1a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin.

Excretory and Urinary System Notes Chapter 15

Functions of the Urinary SystemFunctions of the Urinary System

Slide 15.1aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Elimination of waste products Nitrogenous wastes

Toxins

Drugs

Functions of the Urinary SystemFunctions of the Urinary System

Slide 15.1bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Regulate aspects of homeostasis Water balance

Electrolytes

Acid-base balance in the blood

Blood pressure

Red blood cell production

Activation of vitamin D

Organs of the Urinary systemOrgans of the Urinary system

Slide 15.2Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Kidneys

Ureters

Urinary bladder

Urethra

Figure 15.1a

Location of the Kidneys p 481Location of the Kidneys p 481

Slide 15.3Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Against the dorsal body wall

At the level of T12 to L3

The right kidney is slightly lower than the left

Attached to ureters, renal blood vessels, and nerves at renal hilus

Atop each kidney is an adrenal gland

Coverings of the KidneysCoverings of the Kidneys

Slide 15.4Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Renal capsule Surrounds each kidney

Adipose capsule Surrounds the kidney

Provides protection to the kidney

Helps keep the kidney in its correct location

Regions of the Kidney p 482Regions of the Kidney p 482

Slide 15.5Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Renal cortex – outer region

Renal medulla – inside the cortex

Renal pelvis – inner collecting tube

Figure 15.2b

UretersUreters

Slide 15.20Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Slender tubes attaching the kidney to the bladder

Continuous with the renal pelvis

Enter the posterior aspect of the bladder

Runs behind the peritoneum

Peristalsis aids gravity in urine transport

Urinary BladderUrinary Bladder

Slide 15.21aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Smooth, collapsible, muscular sac

Temporarily stores urine

Figure 15.6

Urinary Bladder WallUrinary Bladder Wall

Slide 15.22Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Three layers of smooth muscle (detrusor muscle)

Mucosa made of transitional epithelium

Walls are thick and folded in an empty bladder

Bladder can expand significantly without increasing internal pressure

UrethraUrethra

Slide 15.23Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Thin-walled tube that carries urine from the bladder to the outside of the body by peristalsis

Release of urine is controlled by two sphincters

Internal urethral sphincter (involuntary)

External urethral sphincter (voluntary)

Nephron Function – “functional unit of the kidney”

Three Processes – Page 4861. Filtration

(blood to capsule)2. Reabsorption

(return to blood)3. Excreted products

(added to urine)

Filtration p 487 Urine formation occurs in millions of units called

nephrons.1. Unfiltered blood enters the renal artery into smaller

arterioles.2. Blood then enters the glomerulus – mass of

capillaries where blood is filtered.3. Large molecules – red and white blood cells,

platelets, plasma proteins, and fats stay in the glomerulus and return through smaller venules into the renal vein

4. Smaller molecules – water, amino acids, salt, glucose, and urea get filtered into the Bowman’s Capsule and travels into the tubules, eventually into the collecting duct

Reabsorption

1. Too much is filtered so amino acids, sugars, and water are reabsorbed depending on what is needed by the body

2. Urine- what’s left over – urea, uric acid, excess water and salt

Excreted Products

Through the process of excretion, almost 100% of nutrients are reabsorbed and essentially all wastes are excreted. Ammonia is extremely toxic to the body and must be constantly flushed from the system

Other excretory organs

Skin – (Perspiration) – get rid of water, salts, and urea.

Lungs – Respiration – excrete CO2 Liver – forms urea when producing bile