Chapter 25 Study Prompts

Approximately how many liters of blood filter through the kidneys each day?

200 L

What types of substances do the kidneys take from the blood and put into urine?

• anything small enough to leave the capillary will come out.

• But only nitrogenous wastes (urea, uric acid, creatinine), excess and ions typically constitute urine

Other than urine formation, what are the functions of the kidneys (renal system)?

regulates volume and makeup of blood, controls blood pressure by water and salt balance, controls pH of the blood, stimulates RBC production and plays a role in vitamin D metabolism

Can you list all of the structures of the urinary system and give a brief description of their function?

Structures:

1. Kidneys- form urine

2. Ureters- convey urine from the kidneys to the urinary bladder

3. Urinary bladder- holds/stores urine

4. Urethra- conveys urine from the bladder to the external environment

Can you describe the location of the kidneys? Which one sits lower than the other and why?

• retroperitoneal.

• The right one sits lower than the left because it is crowded by the liver, but they are generally found between T12 and La.

Can you describe the shape of the kidney?

bean-shaped

What is the portion of the kidney called where blood vessels, nerves, and the ureter enter/leave the kidney?

hilum/hilus

Can you describe the three layers of tissue that support the kidney?

fibrous capsule on the kidney, then perirenal fat capsule, then renal fascia

Can you describe the internal anatomy of the kidney using the following terms, and can you provide a function for these terms? Can you diagram them?

1. Renal pyramids

2. Medulla

3. Cortex

4. Renal columns

5. Renal pelvis

6. Papilla

7. Renal calyx (calyces)

Structure:

1. Renal pyramids- medulla tissue in the center of the kidney, shaped in a pyramid (triangle) shape. Contains collecting ducts that lead the urine from the cortex to the pelvis

2. Medulla- see "renal pyramids"

3. Cortex- outer tissue that is responsible for making urine

4. Renal columns- cortex tissue that dips between the medullary pyramids

5. Renal pelvis- funnel-shaped structure that collects urine and leads it to the ureter

6. Papilla- pointed tips of the pyramid that leads urine into the pelvis

7. Renal calyx- branches of the pelvis

8. See Fig 25.3

Can you describe the blood supply to the kidney? To the nephron?

• the aorta branches to the renal artery which leads blood into the kidney.

• The renal vein leaves the kidney and joins the vena cava. The blood through the nephron is: afferent arteriole glomerulus → efferent arteriole →peritubular capillaries

What is the structural and functional unit of the kidney?

nephron

Can you describe the anatomy of the nephron using the following terms, and can you provide a function for these terms? Can you diagram it?

1. Glomerulus

2. Bowman's (renal) capsule

3. Afferent arteriole

4. Efferent arteriole

5. Peritubular capillaries

6. Proximal convoluted tubule

7. Distal convoluted tubule

8. Loop of Henle

9. Collecting duct

See diagram in lecture Ink. Terms:

1. Glomerulus- tuft of capillaries that allows substances from the blood to leave and form filtrate

2. Bowman's capsule- widened end of the tubular system of the nephron that surrounds the glomerulus, captures the filtrate and leads it into the tubules

3. Afferent arteriole- vessel leading blood into the glomerulus

4. Efferent arteriole- vessel leading blood away from the glomerulus

5. Peritubular capillaries- capillaries that arise from the efferent arteriole and surround the tubules

6. Proximal convoluted tubule- first part of tubule and does mostly reabsorption, some secretion and cells are cuboidal with microvilli

7. Distal convoluted tubule- farthest part of tubule before the collecting duct. Does primarily secretion, some reabsorption and cells are cuboidal without microvilli

8. Loop of Henle- portion of the tubule between the convoluted tubules; is long and
   "U" shaped and has two limbs: descending limb reabsorbs water and ascending limb reabsorbs sodium. Squamous cells.

9. Collecting duct- leads urine through medulla. Has cells with microvilli that do acid-base balancing and cells without that do water-salt balancing

Can you describe the glomerular endothelium?

simple squamous cells of the capillary walls

What is filtrate? Where is it produced?

substance that leaves the blood from the glomerulus- basically plasma, minus proteins

Do you know what podocytes are and what their function is?

cells that have "interdigitating feet" that cover the capillaries of the glomerulus and control what can leave the blood supply

Can you describe filtration slits and how they are formed?

• small slits formed by the "feet" of the podocytes, the walls of the capillaries and the basement membrane between them.

• Only substances small enough to cross this structure can leave the blood and form filtrate.

Can you list and describe the three layers of the filtration membrane?

• small slits formed by the "feet" of the podocytes, the walls of the capillaries and the basement membrane between them.

• Only substances small enough to cross this structure can leave the blood and form filtrate.

Can you give the epithelia type that makes up the following structures and explain what function the epithelia provides for that the structure?

1. Proximal convoluted tubule

2. Distal convoluted tubule

3. Loop of Henle

4. Collecting duct

1. Proximal convoluted tubule- first part of tubule and does mostly reabsorption, some secretion and cells are cuboidal with microvilli

2. Distal convoluted tubule- farthest part of tubule before the collecting duct. Does primarily secretion, some reabsorption and cells are cuboidal without microvilli

3. Loop of Henle- portion of the tubule between the convoluted tubules; is long and
   "U" shaped and has two limbs: descending limb reabsorbs water and ascending limb reabsorbs sodium. Squamous cells.

4. Collecting duct- leads urine through medulla. Has cells with microvilli that do acid-base balancing and cells without that do water-salt balancing

Can you describe the anatomy of the Loop of Henle?

1. Loop of Henle- portion of the tubule between the convoluted tubules; is long and
   "U" shaped and has two limbs: descending limb reabsorbs water and ascending limb reabsorbs sodium. Squamous cells.

Can you trace the flow of urine from the collecting duct to the external environment?

collecting duct medullary pyramid papilla→minor calyx →major calyx → pelvis ureter → bladder → urethra

What are the two capillary beds of the nephron?

glomerulus and peritubular capillaries

Can you describe the location and components of the juxtaglomerular apparatus?

components:

1. macula densa- cluster of cells at the end of the ascending limb of the Loop of Henle and have chemoreceptors to help control water and salt balance, and therefore blood pressure via vasoconstriction

2. juxtaglomerular cells (granular cells) - found around the afferent arteriole and have baroreceptors to detect blood pressure. These cells can secrete renin, which helps to raise blood pressure in response to low blood pressure

What type of cells secrete renin? What is renin used for?

it is a hormone that is made by the kidney, enters the blood and travels to the marrow and stimulates RBC production

What is erythropoietin and what secretes it?

it is a hormone that is made by the kidney, enters the blood and travels to the marrow and stimulates RBC production

Can you describe the structure, location and function of the ureters?

• tubes that run from the kidneys retroperitoneally to the urinary bladder.

• They convey urine to the bladder.

Can you list and describe the layers of the ureter walls?

Layers (from lumen outward):

1. Mucosa- transitional epithelia

2. Muscularis- smooth muscle layers that perform peristalsis to move urine through the tube

3. Adventitia- fibrous CT

Can ureters actively propel urine towards the bladder?

yes, by peristalsis

Can you describe the structure, location and function of the urinary bladder?

located in the pelvic cavity and it is a hollow, muscular sac that can hold/store urine

Can you list and describe the layers of the urinary bladder?

From lumen outwards:

1. Mucosa- transitional epithelia

2. Muscularis- thickened in the bladder and is called the detrusor muscle. This layer contracts to expel urine from the bladder during voiding.

3. Adventitia- fibrous CT

Can you describe the trigone? What is its clinical importance?

• three openings in the bladder- two for the ureters and one for the urethra.

• Clinically important due to bacterial infection

Where is the detrusor muscle located? What is its function?

From lumen outwards:

1. Mucosa- transitional epithelia

2. Muscularis- thickened in the bladder and is called the detrusor muscle. This layer contracts to expel urine from the bladder during voiding.

3. Adventitia- fibrous CT

About how much urine can the bladder hold before it will expel its contents?

800-1000mL (this is 0.8-1.0 L)

Can you describe the structure, location and function of the urethra?

• tube that leaves the urinary bladder and passes urine to the external environment.

• Longer in the male than in the female.

• In the female it is located along the anterior wall of the vagina.

Can you list and describe the sphincters of the urethra?

Sphincters:

a. Internal- smooth muscle, involuntary and is an extension of the detrusor muscle

b. External- skeletal muscle, voluntary and located in the urogenital diaphragm

What is the approximate length of the male urethra? Female urethra?

20cm. 3-4cm.

Can you list and describe the three regions of the male urethra?

Regions:

1. Prostatic urethra- leaving the bladder and surrounded by the prostate gland

2. Membranous urethra- passing through the urogenital diaphragm

3. Spongy urethra- through the penis

What is the name of the process of voiding urine from the body?

micturition

What is incontinence and what factors can lead to incontinence?

the inability to voluntarily hold urine in the bladder. Pregnancy, nervous disorders, old age.....