Today Urinary System Diagram on front table Work on the front side only Use pages to help DO NOT WORK ON THE NEPHRON, WE WILL DO THAT TOGETHER NEXT WEEK Test needs to be made up by next Wednesday (4/13)

The Urinary System

EQ: Discuss the various roles our kidneys play in our body (both in and out of the urinary system). Pg 518 Test needs to be made up by Wednesday (4/13)

Functions of the Urinary System Elimination of waste products –Nitrogenous wastes (nitrogen-containing; i.e. urea) –Toxins –Drugs 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 System Kidneys Ureters Urinary bladder Urethra

Location of the Kidneys Against the dorsal body wall Below T12 Right lower than left –Due to position of liver

Ureters Using pg 528, complete the section in your notes on the ureter

Ureters Slender tubes attaching the kidney to the bladder –Continuous with the renal pelvis Peristalsis aids gravity in urine transport

Urinary Bladder Using pg , complete the section in your notes on the urinary bladder 1 st : Function 2 nd : Description of organ

Urinary Bladder Temporarily stores urine Smooth, collapsible, muscular sac Three openings Two from the ureters One to the urethra –In males, the prostate gland surrounds the neck of the bladder

Urethra Using pg 529, complete the section in your notes on the urethra 1 st : Description of organ Describe the differences in the two sphincters Describe the different functions in males and females

Urethra 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 and made of smooth muscle –External urethral sphincter Voluntary and made of skeletal muscle Function –Females—only carries urine –Males—carries urine and is a passageway for sperm cells

Micturition (Voiding) Stretch receptors in bladder wall signal brain The internal urethral sphincter is relaxed after stretching of the bladder The external urethral sphincter must be voluntarily relaxed to void Both sphincter muscles must open to allow voiding

Regions of the Kidney Renal cortex—outer ring Renal medulla—pyramids Calyces (calyx)—funnel urine towards the renal pelvis from medulla Renal pelvis—inner collecting tube

Regions of the Kidney Figure 15.2a

Nephron Anatomy and Physiology Functional units of the kidneys –Produce Urine Main structures of the nephrons –Blood Supply Glomerulus Peritubular Capillaries –Renal Tubule Proximal (PCT) and Distal Convoluted Tubule (DCT) Loop of Henle extends from glomerular capsule and ends at the collecting duct 1/4 of the total blood supply passes through the nephrons each minute

Types of Nephrons Cortical nephrons (80%) –Located entirely in the cortex –Includes most nephrons Juxtamedullary nephrons –Found at the boundary of the cortex and medulla

Nephron Blood Supply Glomerulus –Knot of capillaries –Glomerulus sits within the Glomerular (Bowman’s) capsule (the first part of the renal tubule) –Capillaries are covered with podocytes from the renal tubule Create filtration slits Peritubular capillaries –Capillaries surrounding the tubule –Absorb substances back into blood that are actively transported out Vasa Recta –Capillaries surrounding the Loop of Henle

Nephron Anatomy Figure 15.3d

Nephron Blood Supply

Nephron Anatomy Renal tubule extends from glomerular capsule and ends at the collecting duct Glomerular (Bowman’s) Capsule Proximal Convoluted Tubule (PCT) Loop of Henle Distal Convoluted Tubule (DCT) Collecting Duct

Urine Formation 1.Glomerular filtration 2.Tubular reabsorption 3.Tubular secretion

1. Glomerular Filtration Fed and drained by arterioles Nonselective passive process ( no energy) High pressure forces water and solutes smaller than proteins through glomerulus walls into Glomerular (Bowman’s) Capsule –H2O –Salts –Glucose –Amino Acids –Urea Proteins and blood cells are normally too large to pass through the filtration slits

2. Reabsorption The peritubular capillaries reabsorb useful substances from the Renal Tubule (mostly PCT) –Water –Glucose –Amino acids –Ions Mostly Active Transport (requires energy) Most reabsorption occurs in the proximal convoluted tubule Materials not reabsorbed –Nitrogenous waste products Urea—protein breakdown Uric acid—nucleic acid breakdown Creatinine—associated with creatine metabolism in muscles

3. Secretion: Reabsorption in Reverse Some materials move from the peritubular capillaries into the renal tubules –Hydrogen and potassium ions –Creatinine Process is important for getting rid of substances not already in the filtrate Materials left in the renal tubule move toward the ureter

Renal Nephron Diagram 1.Select 3 different colored pencils. 2.Assign one to each of the arrows at the top of the page and color them in (active, passive, secretion) 3.Using diagram on pg 525, draw in arrows showing the movement of the following solutes from the tubules back into the blood vessels. Label the solutes! –H2O –Glucose –Amino Acids –Nacl –K+ –H+ 4.Draw in black arrows showing the movement of the filtrate through the tubules

Sites of Filtration, Reabsorption, and Secretion in a Kidney Figure 15.5

Collecting Duct Receives urine from many nephrons Run through the medullary pyramids Deliver urine into the calyces and renal pelvis

Nephron Anatomy Figure 15.4

Characteristics of Urine In 24 hours, about 1.0 to 1.8 liters of urine are produced Urine vs. filtrate –Filtrate -everything in blood plasma (except proteins and blood cells) –Urine - what remains after the filtrate has lost most of its water, nutrients, and necessary ions –Urine contains wastes and substances that are not needed Yellow color due to the pigment urochrome (from the breakdown of bile’s bilirubin) Sterile Normal pH of around 6

Characteristics of Urine Solutes normally found in urine –Sodium and potassium ions –Urea, uric acid, creatinine –Ammonia –Bicarbonate ions

Characteristics of Urine Solutes NOT normally found in urine –Glucose –Blood proteins –Red blood cells –Hemoglobin –White blood cells (pus) –Bile