Module 5 Urinary System

Question 1

Identify the functions of the urinary system and the kidneys (11)

Answer 1

1. Urinary system maintains homeostasis through regulation of plasma composition
2. Maintaining H2O balance in the body
3. Maintaining proper osmolarity of the body fluid (primarily via pt 2)
4. Regulating quantity and concentration of ECF ions (sodium, chloride, potassium, calcium, hydrogen, bicarbonate, phosphate, sulphate and magnesium)
5. Maintaining proper plasma volume
6. Helping maintain proper acid-base balance of the body by adjusting urinary output of H+ and HCO3-
7. Excreting end products of bodily metabolism (urea, uric acid, creatinine)
8. Excreting many foreign compounds
9. Producing erythropoietin
10. Producing renin
11. Converting Vit D to active form

Question 2

Describe the structures of the urinary system, including the kidney’s, ureters, urinary bladder and urethra

The kidneys are bean-shaped organs that reside in the back of the ______\_on each side of the _______. Each kidney has an outer layer called the _______and also has an inner layer called the _______\_, which is composed of the_______. From the renal medulla, urine drains into a ______\_, which empties into a________ and then into the ______\_, before leaving the kidney through the ______\_. The ______\_, a_________, and a ______\_ extend from the central region of each kidney.

Answer 2

The kidneys are bean-shaped organs that reside in the back of the abdominal cavity on each side of the vertebral column. Each kidney has an outer layer called the renal cortex and also has an inner layer called the renal medulla, which is composed of the renal pyramids. From the renal medulla, urine drains into a minor calyx, which empties into a major calyx and then into the renal pelvis, before leaving the kidney through the ureter. The ureter, a renal artery, and a renal vein extend from the central region of each kidney.

Question 3

The functional unit of the kidney is the _____\_

Answer 3

The functional unit of the kidney is the nephron

Question 4

There are approx _______ nephrons per kidney.

The arrangement of the nephrons within the renal cortex and renal medulla is shown in the following figure.

Answer 4

one million

Question 5

3. Describe the Anatomical structures and locations of the tubular and vascular components of the nephron.

Each nephron has two components—a _____\_component and a _____\_ component.

Answer 5

Each nephron has two components—a vascular component and a tubular component.

Question 6

3. Describe the Anatomical structures and locations of the tubular and vascular components of the nephron.

The vascular component contains the ________\_ and includes the

1. ______
2. ______
3. ______
4. ______

Answer 6

The vascular component contains the blood within the nephron and includes the

1. Afferent Arteriole
2. Glomerulus
3. Efferent Arteriole
4. Peritubular Capillaries

Question 7

3. Describe the Anatomical structures and locations of the tubular and vascular components of the nephron.

What is the glomerulus?

A tuft of _____\_ that filters protein-free plasma (from the ________) into the __________.

Blood that is not filtered exits the Glomerulus through the ________

Answer 7

A tuft of capillaries that filters protein-free plasma (from the Afferent Arteriole) into the Tubular Components of the Nephron.

Blood that is not filtered exits the Glomerulus through the Efferent Afterial

Question 8

Describe the blood flow through the kidney

Answer 8

Renal Artery →

Segmental Arteries →

Interlobar Arteries →

Arcuate Arteries →

Interlobular Arteries →

Afferent Arterioles →

Glomerular Capillaries →

Efferent Arterioles →

Peritubular Capillaries →

Interlobular Vein →

Arcuate Veins →

Interlobar Veins →

Renal Vein

Question 9

3. Describe the Anatomical structures and locations of the tubular and vascular components of the nephron.

The tubular component functions in the formation __________

Answer 9

The tubular component functions in the formation of the urine within the nephron

Question 10

3. Describe the Anatomical structures and locations of the tubular and vascular components of the nephron.

The Tubular component of the nephron consists of the

1. _____\_
2. ____\_
3. ____\_
4. ____\_

Answer 10

1. Bowmans Capsule
2. Proximal Tubule
3. Loop of Henle
4. Distal Tubule and Collecting Duct

Question 11

3. Describe the Anatomical structures and locations of the tubular and vascular components of the nephron.

What is the function of each of the components of the Tubular System?

1. Bowmans Capsule:
2. Proximal Tubule
3. Loop of Henle:
4. Distal Tubule and Collecting Duct:

Answer 11

What is the function of each of the components of the Tubular System?

1. Bowmans Capsule: collects glomerular filtrate
2. Proximal Tubule: uncontrolled reabsorption and secretion of selected substances
3. Loop of Henle: Establishes osmotic gradient in Renal Medulla - Important in kidneys ability to produce urine of varying concentrations
4. Distal Tubule and Collecting Duct: Variable, controlled reabsorption of Na+ and H2O and secretion of K+ and H+; fluid leaving CD is urine - enters renal pelvis

Question 12

The region of the nephron where the distal tubule comes into contact with the afferent arteriole, which leads into the glomerulus, and comes into contact with the efferent arteriole, which leads out of the glomerulus, is called the_____________

Answer 12

The region of the nephron where the distal tubule comes into contact with the afferent arteriole, which leads into the glomerulus, and comes into contact with the efferent arteriole, which leads out of the glomerulus, is called the juxtaglomerular apparatus.

Question 13

There are two specialized cell types forming the juxtaglomerular apparatus

1. ________
2. ________

Answer 13

1. macula densa cells
2. granular cells.

Question 14

Macula densa cells are cells of the , which play a role in detecting

Answer 14

Macula densa cells are epithelial cells of the distal tubule, which play a role in detecting salt concentration in the filtrate

Question 15

The granular cells, which surround the , secrete the enzyme

Answer 15

The granular cells, which surround the afferent arteriole, secrete the enzyme renin

Question 16

The enzyme Renin is important in regulating ____________.

Answer 16

The enzyme Renin is important in regulating blood volume and blood pressure.

Question 17

There are two types of Nephrons:

1. ______
2. ______

Answer 17

1. Cortical and
2. Juxtamedullary Nephrons

Question 18

5. Differentiate between Cortical and Juxtamedullary Nephrons

How are the two types of nephrons distinguished?

Answer 18

By their anatomical location

Question 19

5. Differentiate between Cortical and Juxtamedullary Nephrons

• Most nephrons (80%-85%) are cortical nephrons and reside primarily _______\_
• The remaining 15%-20% of nephrons are juxtamedullary nephrons which have ___________\_

Answer 19

• Most nephrons (80%-85%) are cortical nephrons and reside primarily within the cortex
• The remaining 15%-20% of nephrons are juxtamedullary nephrons which have long loops of Henle that extend deep within the medulla

Question 20

Both cortical and juxtamedullary nephrons are involved in the formation of urine; however, ________\_nephrons also play an important role in establishing the medullary vertical osmotic gradient, which allows for __________\_ and for the _______\_ of urine.

Answer 20

Both cortical and juxtamedullary nephrons are involved in the formation of urine; however, juxtamedullary nephrons also play an important role in establishing the medullary vertical osmotic gradient, which allows for water reabsorption and for the concentration of urine.

Question 21

Three basic processes are involved in the formation of urine by the urinary system

1. _________\_
2. _________\_
3. _________\_

Answer 21

Three basic processes are involved in the formation of urine by the urinary system

1. glomerular filtration,
2. tubular reabsorption, and
3. tubular secretion.

Question 22

Glomerular filtration occurs in the __________, where approximately 20% of the blood entering the glomerulus via the afferent arteriole filters into _________\_and becomes the _____\_

Answer 22

Glomerular filtration occurs in the renal corpuscle, where approximately 20% of the blood entering the glomerulus via the afferent arteriole filters into Bowman’s capsule and becomes the filtrate

Question 23

What is Tubular reabsorption?

Answer 23

Selective movement of filtered substances from the tubular lumen into the peritubular capillaries

Question 24

What is Tubular secretion?

Answer 24

Further modification of the filtrate via Selective movement of nonfiltered substances from the peritubular capillaries to the tubular lumen

Question 25

Following tubular reabsorption and tubular secretion, the remaining filtrate is eliminated from the body in the process of _________

Answer 25

Following tubular reabsorption and tubular secretion, the remaining filtrate is eliminated from the body in the process of urine excretion

Question 26

Glomerular filtration occurs across the glomerular membrane by moving solutes and fluid through the ______\_in the capillary ______\_ cells, across the ______\_, and through the slit pores in the tubule epithelial cells (called ______\_)

Answer 26

Glomerular filtration occurs across the glomerular membrane by moving solutes and fluid through the fenestrations in the capillary endothelial cells, across the basement membrane, and through the slit pores in the tubule epithelial cells (called podocytes)

Question 27

The driving force for glomerular filtration is the __________\_ that results from the four starling forces:

1. Glomerular Capillary Hydrostatic Pressure
2. Bowmans capsule Oncotic pressure
3. Glomerular Capillary oncotic pressure
4. Bowman’s capsule hydrostatic pressure

Answer 27

The driving force for glomerular filtration is the net filtration pressure that results from the four starling forces:

1. Glomerular Capillary Hydrostatic Pressure
2. Bowmans capsule Oncotic pressure
3. Glomerular Capillary oncotic pressure
4. Bowman’s capsule hydrostatic pressure

Question 28

Describe each of the starling forces and state whether they Favour filtration or Oppose Filtration across Glomerular capillaries

• Glomerular capillary hydrostatic pressure (P_GC): the __________\_and has an average value of _____\_
  
  • ​____\_ filtration
• Bowman’s capsule oncotic pressure (π_BC): results from _______\_and, under normal renal conditions, is ____\_ because of the ________\_
  
  • ​____\_ filtration
• Glomerular capillary oncotic pressure (π_GC) results from _______\_and has an average value of _____\_
  
  • ​_____\_ filtration (Favours absorption)
• Bowman’s capsule hydrostatic pressure (P_BC) is __________\_and has an average value of ___\_.
  
  • ____\_ filtration (Favours absorption)

Answer 28

Describe each of the starling forces and state whether they Favour filtration or Oppose Filtration across Glomerular capillaries

• Glomerular capillary hydrostatic pressure (P_GC): the blood pressure of the glomerular capillaries and has an average value of 60mmHg
  
  • ​Favours filtration
• Bowman’s capsule oncotic pressure (π_BC): results from proteins in Bowman’s capsule and, under normal renal conditions, is 0mmHg because of the absence of protein in the filtrate
  
  • ​Favours filtration
• Glomerular capillary oncotic pressure (π_GC) results from protein in the glomerular capillaries and has an average value of 29mmHg
  
  • ​Opposes filtration (Favours absorption)
• Bowman’s capsule hydrostatic pressure (P_BC) is the pressure exerted by the filtrate in Bowman’s capsule and has an average value of 15mmHg.
  
  • Opposes filtration (Favours absorption)

Question 29

The net glomerular filtration pressure can be calculated by: totalling the forces ______\_filtration and subtracting the forces _____\_ filtration as shown in the equation:

Answer 29

The net glomerular filtration pressure can be calculated by: totalling the forces favouring filtration and subtracting the forces opposing filtration as shown in the equation:

(P_GC + π_BC) – (π_GC + P_BC)

= (60 mm Hg + 0 mm Hg) – (29 mm Hg + 15 mm Hg)

= 16 mm Hg

• P_GC: Glomerular capillary hydrostatic pressure
• π_BC: Bowman’s capsule oncotic pressure
• π_GC: Glomerular capillary oncotic pressure
• P_BC: Bowman’s capsule hydrostatic pressure

Question 30

Two of the starling forces are higher in the kidney than in other capillaries, which ones and why?

Answer 30

1. Glomerular capillary hydrostatic pressure (P_GC) is the blood pressure of the glomerular capillaries
   
   • higher than that of other capillary beds because of the higher resistance (smaller diameter) of the efferent arteriole compared to that of the afferent arteriole
2. Glomerular capillary oncotic pressure (π_GC) results from protein in the glomerular capillaries
   
   • higher than in other capillary beds because filtration decreases the volume of the plasma (which increases the concentration of protein in the plasma)

Question 31

The rate of filtration through the glomerular capillaries is the _________\_. and is dependent on the________ and the _______\_

What is the equation?

Answer 31

The rate of filtration through the glomerular capillaries is the glomerular filtration rate (GFR). and is dependent on the net glomerular filtration pressure and the filtration coefficient (Kf)

GFR = net glomerular filtration pressure × Kf

Question 32

Kf (the filtration coefficient) is determined by the _________\_and the _________\_

Answer 32

Kf (the filtration coefficient) is determined by the glomerular surface area available for filtration and the glomerular membrane permeability.

Question 33

What is the filtration fraction and how is it calculated?

Answer 33

The filtration fraction is the fraction of plasma that enters Bowman’s capsule as filtrate during glomerular filtration.

Calculated by taking the GFR and dividing it by the renal plasma flow rate