Is the kidney a major homeostatic organ of the body?

Yes

To perform all its functions, the kidney first acts as what type of filter and then as what type of processor?

It first acts as a blood filter and then as a filtrate processor.

The kidney allows what 3 substances to leave the body in the urine while simultaneously doing what?

1. Toxins

2. Metabolic wastes

3. Excess ions

...while simultaneously retaining needed substances and returning them to the blood

Malfunction of the urinary system, especially of the kidneys, leads to a failure in homeostasis, which uncorrected, is fatal. T/F?

True

The urinary system consists of what 4 structures?

1. Kidneys (paired)

2. Ureters (paired)

3. Urinary bladder

4. Urethra

Of the urinary system, the ureters, urinary bladder, and urethra provide what 2 functions?

1. Provide temporary storage reservoirs

2. Act as transportation channels

Why is the right kidney slightly lower than the left kidney?

It is crowded by the liver

How many layers of support tissue surround each kidney (from the innermost layer to the outermost layer)? What are they?

1. Fibrous capsule

2. Perirenal fat capslue

3. Renal fascia

Describe the texture of the renal fascia?

Fibrous

What is the function of the fibrous renal fascia?

Holds the kidneys in place in a retroperitoneal position

In cases of rapid weight loss or in very thin individuals, what may happen to the fat capsule?

It may be reduced in amount

1. When the fat capsule of the kidneys is reduced with rapid weight loss or in very thin individuals, what is the consequence?

2. What is the condition above called?

1. The kidneys are less anchored and may drop to a more inferior position in the abdominal cavity

2. Ptosis

The renal arteries diverge from what major artery and plunge into what area of the kidney?

Diverge from the descending aorta and plunge into the renal hilum

What blood vessels drain the kidneys?

Renal veins

What is the function of the two ureters?

Carry urine from the kidneys to the bladder

How do the two ureters move the urine from the kidneys?

By peristalsis

Is the bladder involved in temporary storage?

Yes

Which part of the urinary system drains the urinary bladder?

The urethra

The triangular region of the bladder that lies above the opening of the urethra and is delineated by the openings of the ureters is referred to as what?

The trigone

The urethra travels the length of what organ in males?

The penis

The urethra in males is made up of what 3 regions?

1. Prostatic urethra

2. Intermediate part of the urethra aka membranous urethra

3. Spongy urethra

1. The male urethra has how many functions?

2. About how long is the male urethra?

1. Two

2. About 20 cm or 8inches long

What are the 2 functions of the male urethra?

1. Carries urine to the body exterior

2. Provides a passageway for semen ejaculation

In males, the urethra is part of what 2 systems?

1. Urinary system

2. Reproductive system

1. Compared to the male urethra, are there any reproductive pathways in the female urethra?

2. About how long is the female urethra?

1. No

2. About 4 cm or 1.5 inches long

What is the sole function of the female urethra?

Serves to transport urine to the body exterior

What is the external opening of the male and female urethra?

The external urethral orifice

How does the fibrous capsule adhere to the kidney and to which aspect? (Hint: think external or internal.)

Adheres tightly to the external aspect of the kidney

What 3 structures enter the renal hilum?

1. Ureter

2. Renal vein

3. Renal artery

Of the ureter, renal vein, and renal artery, which one has the thinnest wall and will be collapsed?

Renal vein

Of the ureter, renal vein, and renal artery, which one has the thickest wall?

Ureter

Where is the renal cortex located?

Superficial kidney region or outermost region

The renal cortex is rich in what type of supply?

Vascular supply

In the medullary region, the medulla is separated into what regions?

Renal pyramids

How do the renal pyramids appear? (Hint: striped or non-striped?)

They are striped

The base of each pyramid faces toward what region of the kidney?

Toward the cortex of the kidney

The part of the renal pyramids that points to the innermost kidney region is called what?

Papilla or apex

The renal columns are similar in appearance to what region of the kidney?

The renal cortex

What is the function of the renal columns?

Separate the renal pyramids

Extending inward from the hilum is what basin-like cavity that is continuous with the ureter?

The renal pelvis

The ureter exits from what region of the kidney?

The hilum region

What is the larger or primary extension of the renal pelvis called?

Major calyx

A smaller subdivision of the major calyx is called what?

Minor calyx

A minor calyx terminates in cup-like areas that enclose what?

The apexes or papilla of the renal pyramids

What is the function of a minor calyx?

To collect urine draining from the apexes or papilla of the renal pyramids and transfer it to the renal pelvis

What fraction of the total blood flow of the body is delivered to the kidneys each minute?

1/4

What vessels deliver blood to the kidneys?

Renal arteries

As a renal artery approaches the kidney, it breaks up into what arteries?

Segmental arteries

1. The segmental arteries enter what region of the kidneys?

2.The segmental arteries further break up into what arteries?

1. Renal hilum

2. Interlobar arteries

The interlobar arteries extend outward toward what region of the kidneys?

Renal cortex

Approaching the base of the renal pyramids, the interlobar arteries further branch into what arteries?

Arcuate arteries

The arcuate arteries curve over which part of the renal pyramids?

Base of the renal pyramids

The arcuate arteries further branch into what arteries and extend into what region of the kidneys?

Further branch into cortical radiate arteries that ascend into the cortex

In the cortical region of the kidneys, the cortical radiate arteries further branch off into what blood vessels?

Afferent arterioles

Afferent arterioles enter which specific structure of the kidney? (Hint: part of the nephron)

The glomerulus

The glomerulus is a ball of what blood vessel?

A ball of capillaries

What blood vessels drain the glomerulus?

Efferent arterioles

The efferent arterioles that drain the glomerulus feed into one of what 2 capillary beds?

1. Peritubular capillaries

2. Vasa recta

Blood draining from the peritubular capillaries or vasa recta then enter what blood vessels?

The cortical radiate veins

The cortical radiate veins then drain into what blood vessels?

Arcuate veins

The arcuate veins then drain into what blood vessels?

Interlobar veins

The interlobar veins then drain into what blood vessel?

The renal vein

The renal veins then drain into what major blood vessel?

The inferior vena cava

Trace a drop of blood from the renal artery to the renal vein. (Hint: 13 steps)

1. Renal artery

2. Segmental arteries

3. Interlobar arteries

4. Arcuate arteries

5. Cortical radiate arteries

6. Afferent arterioles

7. Glomerulus

8. Efferent arterioles

9. Vasa recta or peritubular capillaries

10. Cortical radiate veins

11. Arcuate veins

12. Interlobar veins

13. Renal vein

Each kidney contains over a million what?

Nephrons

What are the structural and functional units of the kidneys?

Nephrons

What are the 2 functions of the nephrons?

1. Filtering the blood

2. Forming urine

Each nephron consists of what 2 major structures?

1. Renal corpuscle

2. Renal tubule

What are the 3 structures within the renal corpuscle? (Hint: Think capillaries and 2 other layers)

1. Glomerulus

2. Visceral layer of the glomerular capsule

3. Parietal layer of the glomerular capsule

The glomerulus is made up of what epithelium?

Fenestrated endothelium or simple squamous epithelium

What is the function of the glomerulus?

Forms part of the filtration membrane

The visceral layer of the glomerular capsule is composed of what type of cells?

Podocytes

The visceral layer of the glomerular capsule is composed of what type of epithelium?

Simple squamous epithelium

What is the function of the podocytes of the visceral layer of the glomerular capsule?

Forms part of the filtration membrane

The spaces between the podocytes form what type of slits?

Filtration slits

The parietal layer of the glomerular capsule is composed of what type of epithelium?

Simple squamous epithelium

What is the function of the parietal layer of the glomerular capsule?

Forms the outside of the glomerular capsule

Does the parietal layer of the glomerular capsule play any role in filtration?

No

What are the 6 structures within the renal tubule (following the glomerular capsule)?

1. Proximal convoluted tubule (PCT)

2. Descending limb of the nephron loop

3. Descending thin limb of the nephron loop

4. Thick ascending limb of the nephron loop

5. Distal convoluted tubule (DCT)

6. Collecting duct

What is the epithelium of the proximal convoluted tubule?

Simple cuboidal

1. Does the proximal convoluted tubule contain many mitochondria?

2. Does the proximal convoluted tubule contain many microvilli?

1. Yes

2. Yes

1. What is the main function of the proximal convoluted tubule?

2. Does some secretion also occur?

1. Primary site of tubular reabsorption of water and solutes

2. Yes

What is the epithelium of the descending limb of the nephron loop?

Simple cuboidal epithelium

What is the microvilli concentration like in the descending limb of the nephron loop?

Some microvilli, decreased in number compared to the concentration seen in the PCT

What are the 2 functions of the descending limb of the nephron loop?

1. Tubular reabsorption

2. Tubular secretion

What is the epithelium of the descending thin limb of the nephron loop?

Simple squamous epithelium

What is the concentration of aquaporins like in the descending thin limb of the nephron loop?

Many aquaporins

1. What is the main function of the descending thin limb of the nephron loop? (Hint: think water)

2. Is the descending thin limb of the nephron permeable to water?

1. Water is reabsorbed, but no solutes are reabsorbed.

2. Yes

What are the 2 epitheliums of the thick ascending limb of the nephron loop?

1. Cuboidal epithelium

2. Low columnar epithelium

What is the concentration of aquaporins like in the thick ascending limb of the nephron loop?

Very few aquaporins

1. What is the main function of the thick ascending limb of the nephron loop?

2. Is the thick ascending limb of the nephron loop permeable to water?

1. Passive and active reabsorption of solutes

2. Not permeable to water

What is the epithelum of the distal convoluted tubule?

Simple cuboidal

1. What is the microvilli concentration in the distal convoluted tubule?

2. What is the mitochondria concentration in the distal convoluted tubule?

1. Few microvilli

2. Many mitochondria

What are the 2 main functions of the distal convoluted tubule?

1. Some reabsorption of water and solutes

2. Some secretion

The collecting duct receives filtrate from what structure within the renal tubule?

Receives filtrate form the distal collecting tubule of many nephrons

What is the epithelium of the collecting duct?

Simple cuboidal

What 2 specialized cells are also found in the collecting duct?

1. Principal cells

2. Intercalated cells

1. What is the function of principal cells?

2. What is the function of intercalated cells?

1. Electrolyte homeostasis

2. Maintain acid-base homeostasis

What are the 4 functions of the collecting duct?

1. Some reabsorption of body fluids

2. Some secretion of body fluids

3. Maintain blood pH

4. Regulate solute concentrations

What are the 2 kinds of nephrons?

1. Cortical nephrons

2. Juxtamedullary nephrons

What are the most numerous type of nephrons, and they comprise what percentage of all the body's nephrons?

Cortical nephrons are the most numerous ones, and they make up about 85% of all nephrons

Cortical nephrons are located almost entirely within what region of the kidney?

The renal cortex

Although cortical nephrons are almost entirely located within the renal cortex, small parts of their loops do dip into what area of the kidney?

The renal medulla

How are the renal corpuscles of juxtamedullary nephrons different from the renal corpuscles of cortical nephrons (in regards to location in the renal cortex)?

The renal corpuscles of juxtamedullary nephrons are located deep in the renal cortex at the border with the renal medulla

How are the long nephron loops of juxtamedullary nephrons different from the nephron loops of cortical nephrons (in regards to location in the renal medulla)?

Their long nephron loops penetrate deeply into the medulla

Which group of nephrons play an important role in concentrating urine?

Juxtamedullary nephrons

The function of the nephron depends on what 3 features of renal circulation?

1. Glomerular filtration

2. Tubular resorption

3. Tubular secretion

What are the 3 capillary vascular supply of nephrons?

1. Glomerulus

2. Pertitubular capillary bed

3. Vasa recta

Of the 3 capillary beds, glomerulus, peritubular capillary bed, and vasa recta, which one is first encountered in the nephron?

Glomerulus

Vessels leading to and from the glomerulus are what type of arterioles?

Glomerular arterioles

Which arteriole feeds the glomerulus and which arteriole drains it?

The afferent arteriole feeds the glomerulus, and the efferent arterole drains it.

Why is the glomerular capillary bed unique in the body? (Hint: think pressure)

It is a high-pressure bed

The glomerular capillary bed is a high-pressure bed because of what reason?

The afferent feeder arteriole is larger in diameter than the efferent arteriole draining it

How are fluid and blood components smaller than proteins forced out of the glomerulus into the glomerular capsule?

The afferent and efferent arterioles create high hydrostatic pressure to force fluid and blood components out of the glomerulus into the glomerular capsule

Fluid and blood components forced out of the glomerulus into the glomerular capsule (through the high hydrostatic pressure created by afferent and efferent arterioles) form what, and what is it processed by?

The filtrate is formed, which is processed by the nephron tubule

Efferent arterioles that supply cortical nephrons and drain the glomerulus tend to form what specific type of capillary bed?

The peritubular capillary bed

How does this set of capillaries cling to the renal tubule?

They cling very closely to the renal tubule

Describe the peritubular capillary bed in regards to pressure and porosity?

Low-pressure, high porosity

The peritubular capillary bed is mainly adapted for what function? (Hint: absorption or filtration?)

Absorption

Since the peritubular capillary bed is mainly adapted for absorption rather than filtration, what 2 substances does it take up from the filtrate?

1. Solutes

2. Water

Which cells process and resorb the solutes and water of the filtrate, two substances that are eventually absorbed again by the peritubular capillary bed?

Tubule cells

Efferent arterioles that supply juxtaglomerular nephrons tend not to form peritubular capillaries, and instead, form what specific capillary bed?

The vasa recta

Differentiate the structure of the peritubular capillary bed and the vasa recta in regards to structure and how the run to their nephron loops.

The peritubular capillary bed clings intimately to its renal tubule and is very coiled. The vasa recta runs parallel to its renal tubule and also clings close, but it is not coiled.

The vasa recta is essential for what to happen?

The concentration of urine

Each nephron also has what complex?

A juxtaglomerular complex

Where is the juxtaglomerular complex located? (Hint: think of the nephron loop and the afferent arteriole)

Located where the most distal portion of the ascending limb of the nephron loop touches the afferent arteriole

What 2 cell types form the juxtaglomerular complex?

1. Granular cells or juxtaglomerular cells

2. Macula densa cells

1. The granular cells or juxtaglomerular cells are located where?

2. What is their function?

1. Located in the arteriole walls of the afferent arteriole

2. Sense blood pressure in the afferent arteriole

1. The macula densa cells are located where?

2. What is their function?

1. Located in the most distal portion of the ascending limb of the nephron loop

2. Monitors sodium chloride concentration in the filtrate

What are the 2 functions of the juxtaglomerular complex?

1. Regulate the rate of filtration based on the salt concentration

2. Regulate systemic blood pressure

Urine forms as a result of what 3 processes?

1. Glomerular filtration

2. Tubular resorption

3. Tubular secretion

Glomerular filtration is accomplished by feature of the nephron?

The glomerulus

Is glomerular filtration passive or active?

Passive

Describe glomerular filtration.

A portion of the blood passes from the glomerular capillary into the glomerular capsule

What happens during tubular resorption? (Hint: Filtrate components move through what cells and return to what?)

Filtrate components move through the tubule cells and return to the blood in the peritubular capillaries

1. Is tubular resorption passive or active, or both?

2. If both, describe what is passively resorbed (by what process) and what is actively resorbed?

1. Both

2. Water is passively resorbed by osmosis, but most substances are actively resorbed.

What are 3 substances that are almost entirely resorbed from the filtrate?

1. Water

2. Glucose

3. Amino acids

Of water, glucose, and amino acids, what is passively resorbed, and what 2 are actively resorbed?

Water is passively resorbed, while glucose and amino acids are actively resorbed.

Is active resorption highly selective?

Yes

Various ions are selectively resorbed or allowed to go out into the urine based on what 2 conditions?

1. What is required to maintain appropriate blood pH

2. What is required to maintain appropriate electrolyte composition

What 4 substances are resorbed to a lesser degree or not resorbed at all?

1. Urea

2. Creatinine

3. Uric acid

4. Drug metabolites

Most of tubular resorption occurs in what part of the nephron tubule? (Hint: Give the percentage of tubular resorption for the associated part of the tubule)

Most (about 75-85%) of tubular resorption occurs in the proximal convoluted tubule

Tubular secretion is the reverse process of what of the 3 process that form urine: glomerular filtration, tubular resorption, and tubular secretion?

Tubular resorption

1. What 3 substances move from the blood of the peritubular capillaries through the tubular cells into the filtrate to be disposed of in urine?

2. Describe the process of tubular secretion from the blood in the peritubular capillaries to urine. (Hint: 4 steps)

1. Hydrogen

2. Potassium ions

3. Creatinine

____________________

1. Peritubular capillaries

2. Tubular cells

3. Filtrate

4. Urine

Identify the blanks.

Identify the blanks.

Identify the blanks.

Identify the blanks.

Identify the blanks.

Identify the blanks.

Identify the blanks.

Identify the blanks.

Identify the blanks.

Identify the blanks.