THE URINARY SYSTEM

Objectives1. Identify the components of the urinary system, and describe the functions it

performs.2. Describe the location and structural features of the kidneys, identify major blood

vessels associated with each kidney, trace the path of blood flow through a kidney, describe the structure of a nephron, and outline the processes involved in urine formation.

3. Discuss the major functions of each portion of the nephron and collecting system, and describe the primary factors responsible for urine production.

4. Describe the factors that influence glomerular filtration pressure and the rate of filtration formation.

5. Identify the types and functions of transport mechanisms found along each segment of the nephron, explain the role of countercurrent multiplication, describe hormonal influence on the volume and concentration of urine, and describe the characteristics of a normal urine sample.

6. Describe the structures and functions of the ureters, urinary bladder, and urethra, discuss the voluntary and involuntary regulation of urination, and describe the micturation reflex.

7. Describe the effects of aging on the urinary system.8. Give examples of interactions between the urinary system and each of the organ

systems.

Functions of Urinary System

Regulate blood ______________ and blood

____________________

Regulate ______________________

concentrations of sodium, potassium, chloride and

other _____________

Help stabilize blood _________________

_______________________________

valuable nutrients

Assist ___________________ in detoxifying

poisons

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Position of Kidney

Dorsal body wall

_______________________________________

Position maintained by:

Peritoneum

Other visceral organs

Supporting connective tissues

Renal _________________________

________________________ capsule

Renal fascia

Kidney

_____________________

_______________________

Renal sinus

Renal hilus

Calyces

major and minor

Columns

____________________________

Blood Supply to Kidneys

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The Nephron (vessels)

Interlobular artery

_____________________________ arteriole

___________________________ ___________________________

Efferent arteriole

________________________________ capillaries

Vasa recta

Interlobular vein

Histology of Nephron and Collecting System Glomerulus Proximal CT Loop of Henle or Nephron Loop Distal CT Collecting Duct

The Renal Corpuscle

Afferent arteriole

Glomerular capillary

_________________________________

Efferent arteriole

_________________________________ CT

_________________________ apparatus

Urine Formation

_________________________________

Filtration membrane

Fenestrated capillaries

Lamina densa

Podocytes (pedicels)

Pressure forces fluid and solutes out of blood

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99% of filtrate is ____________________________________ by the peritubular

capillary bed that arises from the efferent arterioles

_____________________________________

Filtration

_____________________________ __________________________

(Fenestration)

Pores ranging from 60-100 nm

Prevent passage of blood cells

Lamina densa (____________________ _____________________________-)

Smaller openings

Small plasma proteins, nutrients and ions

Filtration ______________________________ (Podocyte foot processes)

Gaps only 6-9 nm

Block all but very small plasma proteins (albumins)

Filtration Pressures Glomerular Hydrostatic pressure (GHP) Capsular hydrostatic pressure (CsHP) NHP=GHP-CsHP = 50 mmHg-15 mm Hg Blood Colloid Osmotic Pressure (BCOP) Filtration Pressure FP=NHP-BCOP = 35 mmHg- 25 mm Hg

Glomerular Filtration Rate

125 mL/min

Generates an average of 180 Liters/day (_______________ gallons)

Can be measured using __________________ Clearance Test (More accurate

inulin)

_________________ is reabsorbed

Regulation of GFR

__________________________________

Dilation of afferent arteriole

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Relaxation of supporting cells and dilation of glomerular capillaries

Constriction of efferent arteriole

___________________________________ regulation

Renin-angiotension system

Atrial Natriuretic Peptide (ANP)

___________________________________ regulation

Vasoconstriction of the afferent arterioles, decreasing the GFR.

Characteristics of Carrier-mediated transport A specific substrate binds to a carrier protein that facilitates movement across the membrane A given carrier protein normally works in one direction only The distribution of carrier proteins can vary from one portion of the cell surface to another The membrane of a single tubular cell contains many types of carrier protein Carrier proteins, like enzymes, can be saturated

Proximal Convoluted Tubule

Reabsorption of

________________________ nutrients

(___________________________, amino acids,

vitamins)

_________________________________ reabsorption of ions (Na+, K+, HCO3-)

Reabsorption of water (____________________________________)

_____________________________ reabsorption of ions (urea, Cl-, lipid-

soluable)

Secretion of H+ ions

Loop of Henle

_________________________________ Multiplication

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Sodium and chloride are pumped ______________________ of the thick

______________________ limb and into peritubular fluid

This pumping elevates the ________________________ concentration in the

peritubular fluid around the thin descending limb.

The result is an osmotic flow of water __________________ of the thin

descending limb and into the peritubular fluid, ______________________________ the

solute concentration in the thin descending limb

The arrival of the highly concentrated solution in the thick ascending limb

_____________________________ the _________________________ of sodium and

chloride ions into the peritubular fluid of the medulla

Distal Convoluted Tubule

__________________________

Active transport of Sodium and Chloride ions

_________________________________ influenced water reabsorption

Calcium reabsorption influenced by parathyroid and calcitrol hormones

____________________________

Potassium ion

Hydrogen ion

Toxins

________________________________________

Collecting System

__________________________________

Sodium ion reabsorption

Bicarbonate reabsorption

Urea reabsorption

_________________________________ ( ________________________ of pH)

Hydrogen ions, Bicarbonate ions

Renin-angiotension Control

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Peripheral capillary beds – brief, but powerful vasoconstriction

______________________________ – constriction of the efferent arteriole

_____________________________ glands –secretion of aldosterone (accelerates

sodium reabsorption)

CNS

Sensation of _________________________________

Release of __________________________________

Sympathetic motor tone causing vasoconstriction

Control of Urine Volume

______________________________________

Water conserver

______________________________________

Salt and water conserver

________________________________________

Salt and water loser

Urine Color Yellow color due to urochrome Odor Ammonia odor due to bacterial metabolism of urea pH Usually about 6, but varies between 4.5-8 Specific gravity Between 1.001 to 1.035 Chemical composition 95% water, urea, Na, K, P & S ions, creatinine, uric acid, Ca, Mg, CO3-

Ureters

Conveys urine from kidneys to

bladder

Consists of four layers:

Mucosa

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Submucosa

Muscularis

Fibroserosa

Renal

___________________________

= kidney stones

Urinary Bladder

Urethra

Thin-walled muscular tube

______________________________ _________________________________

___________________________________________

_______________________________ urethral sphincter

_________________________________

________________________________ urethral sphincter

Voluntary

Urinalysis Routine Color Turbidity Odor Specific gravity Volume Microscopic Sediment from being centrifuged Blood Abnormal cells Chemical pH Glucose Acetone albumin

Disorders

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________________________________________ disorders

Renal calculi

Renal colic

Neurogenic bladder

Tumors

Hematuria

________________________________________ tract infections UTI

Urethritis

Gonorrhea

Chlamydial infections

Cystitis

Pyelonephritis

___________________________________________ disorders

Glomerulornephritis

Nephrotic syndrome

Proteinuria

Hypoalbuminemia

Edema

Artificial Kidney

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