Urinary 1

Question 1

The urinary system has several vital roles in maintaining homeostasis in the body:
* Cleansing the … and ridding the body of …
* Regulation of … (shared with the lungs and the buffers in the blood)
* Regulation of … (shared with the heart and blood vessels)
* Regulating the concentration of … in the blood
* Helps determine the concentration of… (… production)
* Performs the final synthesis step in … activation (converting calcidiol to calcitriol)

If the kidneys fail, these functions are compromised or lost altogether, with devastating effects on homeostasis
The affected individual might experience …, …, shortness of breath, anemia, widespread … (swelling), metabolic acidosis, rising potassium levels, heart arrhythmias, and more…
Since each of these functions are vital to your well-being it is critical, we have a functioning urinary system for our survival

Answer 1

The urinary system has several vital roles in maintaining homeostasis in the body:
* Cleansing the blood and ridding the body of wastes
* Regulation of pH (shared with the lungs and the buffers in the blood)
* Regulation of blood pressure (shared with the heart and blood vessels)
* Regulating the concentration of solutes in the blood
* Helps determine the concentration of red blood cells (erythropoietin production)
* Performs the final synthesis step in vitamin D activation (converting calcidiol to calcitriol)

If the kidneys fail, these functions are compromised or lost altogether, with devastating effects on homeostasis
The affected individual might experience weakness, lethargy, shortness of breath, anemia, widespread edema (swelling), metabolic acidosis, rising potassium levels, heart arrhythmias, and more…
Since each of these functions are vital to your well-being it is critical, we have a functioning urinary system for our survival

Question 2

stores urine until a convenient time for disposal
* External excretion from the body is controlled by our … system
Failure of nervous control or the anatomical structures leading to a loss of control of urination results in …

urine is a regulator of …

The kidneys roughly the size of your fist and are extremely well vascularized, receiving
~…% of resting cardiac output

• The adrenal cortex directly influences renal function through the production of the hormone … to stimulate … reabsorption
• The adrenal medulla releases the catecholamines (… and …)

Answer 2

stores urine until a convenient time for disposal
* External excretion from the body is controlled by our nervous system
Failure of nervous control or the anatomical structures leading to a loss of control of urination results in incontinence

urine is a regulator of plasma

The kidneys roughly the size of your fist and are extremely well vascularized, receiving
~20-25% of resting cardiac output

• The adrenal cortex directly influences renal function through the production of the hormone aldosterone to stimulate sodium reabsorption
• The adrenal medulla releases the catecholamines (epinephrine and norepinephrine)

Question 3

The renal columns are connective tissue extensions that radiate downward from the cortex through the medulla to separate the most characteristic features of the medulla, the …

renal pyramids are bundles of … that transport urine from the nephrons to the … of the kidney for excretion
The renal columns also serve to divide the kidney into … and provide a … framework for vessels which enter and exit the cortex
* The pyramids and renal columns taken together constitute the …

The renal hilum (much like the pulmonary hilum) is the … for structures servicing the kidneys
* Emerging from the hilum is the renal …, which is formed from the major and minor … in the kidney
* The renal arteries form directly from the descending aorta, whereas the renal veins return cleansed blood directly to the inferior vena cava

Answer 3

The renal columns are connective tissue extensions that radiate downward from the cortex through the medulla to separate the most characteristic features of the medulla, the renal pyramids

renal pyramids are bundles of collecting ducts that transport urine from the nephrons to the calyces of the kidney for excretion
The renal columns also serve to divide the kidney into 6–8 lobes and provide a supportive framework for vessels which enter and exit the cortex
* The pyramids and renal columns taken together constitute the kidney lobes

The renal hilum (much like the pulmonary hilum) is the entry and exit site for structures servicing the kidneys
* Emerging from the hilum is the renal pelvis, which is formed from the major and minor calyxes in the kidney
* The renal arteries form directly from the descending aorta, whereas the renal veins return cleansed blood directly to the inferior vena cava

Question 4

Nephrons are the … units of the kidney and are responsible for cleansing the … and … the contents of the circulatory system
* The afferent arterioles supply blood through the …
* Bowman’s capsule (glomerular capsule) surrounds the … and receives the …
The glomerulus and Bowman’s capsule together form the renal …

After passing through the renal …, the capillaries form a second arteriole, the … arteriole
The efferent arteriole then form a … around the more distal portions of the nephron tubule, the … capillaries and …, before returning blood to the venous system
* As the glomerular filtrate progresses through the nephron, these capillary networks …. most of the … and …, and return them to the … system

Answer 4

Nephrons are the functional units of the kidney and are responsible for cleansing the blood and balancing the contents of the circulatory system
* The afferent arterioles supply blood through the high-pressure glomerulus capillaries
* Bowman’s capsule (glomerular capsule) surrounds the glomerulus and receives the filtrate
The glomerulus and Bowman’s capsule together form the renal corpuscle

After passing through the renal corpuscle, the capillaries form a second arteriole, the efferent arteriole
The efferent arteriole then form a capillary network around the more distal portions of the nephron tubule, the peritubular capillaries and vasa recta, before returning blood to the venous system
* As the glomerular filtrate progresses through the nephron, these capillary networks recover most of the solutes and water, and return them to the circulatory system

Question 5

• All of the renal corpuscles as well as both the proximal convoluted tubules (PCTs) and distal convoluted tubules are found where?

SHORT LOOP OF HENLE: … nephrons

LONG LOOP OF HENLE: … nephrons

Answer 5

• All of the renal corpuscles as well as both the proximal convoluted tubules (PCTs) and distal convoluted tubules are found here: CORTEX

SHORT LOOP OF HENLE: cortical nephrons

LONG LOOP OF HENLE: juxtamedullary nephrons, INTO THE MEDULLA

Question 6

Nephron
Nephrons take the … from the blood, alter it at different parts of the nephron before it is disposed of as …
* The principal task of the nephron is to balance the … to homeostatic set points and excrete potential … in the urine
This is accomplished via three principal functions:
* …
* …
* …

secondary functions
* Maintain … (via production of …)
* Aid in … (via the hormone …)
* Assist in … absorption (via …, the active form of vitamin D)

The projections in Bowman’s capsule form …, small gaps between the digits basically forming a strainer for the blood.
* As blood passes through the glomerulus, …% of the plasma filters between these fenestrations which permit very rapid movement of filtrate from the capillary to Bowman’s capsule

Answer 6

Nephron
Nephrons take the filtrate from the blood, alter it at different parts of the nephron before it is disposed of as urine
* The principal task of the nephron is to balance the plasma to homeostatic set points and excrete potential toxins in the urine
* Filtration
* Reabsorption
* Secretion

secondary functions
* Maintain blood pressure (via production of renin)
* Aid in red blood cell production (via the hormone EPO)
* Assist in calcium absorption (via calcitriol, the active form of vitamin D)

The projections in Bowman’s capsule form filtration slits, small gaps between the digits basically forming a strainer for the blood.
* As blood passes through the glomerulus, 10-20% of the plasma filters between these fenestrations which permit very rapid movement of filtrate from the capillary to Bowman’s capsule

Question 7

Nephron
The fenestrations prevent filtration of … or …, but allow most other constituents through
* Substances readily cross if they are <4 nm in size and most pass freely up to 8 nm
An additional factor affecting the ability of substances to cross this barrier is their …
* The proteins associated with these pores are … charged, so they tend to repel … charged substances and allow … charged substances to pass more readily

creation of a filtrate which:
* Does not contain … (…) or large proteins (e.g. … stays in bloodstream)
* Has a slight predominance of … charged substances (e.g. … and …)

From bowman’s capsule, filtrate goes into PCT, formed by … cells which form a … They create a large …, to maximize reabsorption of …, …, and most importantly: ……….

How important?

Answer 7

Nephron
The fenestrations prevent filtration of blood cells or large proteins, but allow most other constituents through
* Substances readily cross if they are <4 nm in size and most pass freely up to 8 nm
An additional factor affecting the ability of substances to cross this barrier is their electric charge
* The proteins associated with these pores are negatively charged, so they tend to repel negatively charged substances and allow positively charged substances to pass more readily

creation of a filtrate which:
* Does not contain cells (RBCs) or large proteins (e.g. albumin stays in bloodstream)
* Has a slight predominance of positively charged substances (e.g. Na+ and K+)

From bowman’s capsule into PCT, formed by simple cuboidal cells which form a brush border. They create a large Surface Area, to maximize reabsorption of Na+, Cl-, and most importantly: glucose

most essential function of this portion of the nephron

Question 8

descending loop consists of an initial short, … portion and long, … portion,

ascending loop consists of an initial short, … portion followed by a long, … portion

• The thick portion of the loop consists of … epithelium
• The thin portions consists of …. epithelium
  This change in epithelium is important as the different portions of the loop have
  different permeabilities for … and …

The distal convoluted tubule is formed by … epithelium
The DCT differs from the PCT as it is much … and is … active in absorbtion/secretion
Brush border?

Answer 8

descending loop consists of an initial short, thick portion and long, thin portion,

ascending loop consists of an initial short, thin portion followed by a long, thick portion

• The thick portion of the loop consists of simple cuboidal epithelium
• The thin portions consists of simple squamous epithelium
  This change in epithelium is important as the different portions of the loop have
  different permeabilities for solutes and water

The distal convoluted tubule is formed by simple cuboidal epithelium
The DCT differs from the PCT as it is much shorter and is less active in absorbtion/secretion
No brush border

Question 9

The juxtaglomerular apparatus is the juncture where:
* The …. enter and leave Bowman’s capsule
* The … comes into direct contact with both …

This intersection contains the … and …
* It monitors the composition (…) and rate of fluid flowing (…- and …) through the distal convoluted tubule

In response to the … of Na+ in the fluid and how … fluid is flowing

The macula densa, release … signals
* These signals consist of … (…) and adenosine

The juxtaglomerular cell
* A modified, … cell lining the afferent arteriole that can … in response to … or adenosine

IN PHOTO
1. GFR increases.
2. Flow through the tubule …
3. Flow past the macula densa …
4. … signals are released from the macula densa to the afferent arteriole.
5. The afferent arteriole …
6. Resistance in the afferent arteriole …
7. Hydrostatic pressure in the glomerulus …
8. GFR …

Answer 9

The juxtaglomerular apparatus is the juncture where:
* The afferent and efferent arterioles enter and leave Bowman’s capsule
* The DCT comes into direct contact with both arterioles
This intersection contains the macula densa and juxtaglomerular cells
* It monitors the composition (chemoreceptors) and rate of fluid flowing (mechano- and baroreceptors) through the distal convoluted tubule

In response to the concentration of Na+ in the fluid and how fast the fluid is flowing

The macula densa, release paracrine signals
* These signals consist of adenosine triphosphate (ATP) and adenosine
The juxtaglomerular cell

• A modified, smooth muscle cell lining the afferent arteriole that can contract or relax in response to ATP or adenosine

1. GFR increases.
2. Flow through the tubule increases.
3. Flow past the macula densa increases.
4. Paracrine signals are released from the macula densa to the afferent arteriole.
5. The afferent arteriole constricts.
6. Resistance in the afferent arteriole increases.
7. Hydrostatic pressure in the glomerulus decreases.
8. GFR decreases.

Question 10

↑ Filtrate osmolarity (…osmotic): juxtaglomerular cells … → … GFR → … urine formation → … water retention → … blood osmolarity

↓ Filtrate osmolarity (…osmotic): juxtaglomerular cells … → … GFR → … urine formation → … water loss → … blood osmolarity

• When osmolarity goes up, filtration and urine formation … and water is …
• When osmolarity goes down, filtration and urine formation … and water is …

Answer 10

↑ Filtrate osmolarity (hyperosmotic): juxtaglomerular cells contract → ↓ GFR → ↓ urine formation → ↑ water retention → ↓ blood osmolarity

↓ Filtrate osmolarity (hypoosmotic): juxtaglomerular cells relax → ↑ GFR → ↑ urine formation → ↑ water loss → ↑ blood osmolarity

• When osmolarity goes up, filtration and urine formation decrease and water is retained
• When osmolarity goes down, filtration and urine formation increase and water is lost by way of the urine

Question 11

A second function of the macula densa cells is to regulate … from the juxtaglomerular cells of the afferent arteriole

• Active renin + angiotensinogen = angiotensin I
• Angiotensin I + (ACE) at the lungs = angiotensin 2
• Angiotensin II is a systemic … in turn … blood pressure

Angiotensin II stimulates … from the adrenal cortex
* … in turn stimulates … by the kidney, which also results in water … and … blood pressure

ANH = ANP
antagonist to …
excrete …
inhibit …, … release
More or less water recovered?

Answer 11

A second function of the macula densa cells is to regulate renin release from the juxtaglomerular cells of the afferent arteriole

• Active renin + angiotensinogen = angiotensin I
• Angiotensin I + (ACE) at the lungs = angiotensin 2
• Angiotensin II is a systemic vasoconstrictor in turn increase blood pressure

Angiotensin II stimulates aldosterone from the adrenal cortex
* Aldosterone in turn stimulates Na+ reabsorption by the kidney, which also results in water retention and increased blood pressure

ANH = ANP
antagonist to ANG II
excrete Na+
inhibit aldosterone, ADH release
More or less water? Less water recovered, more to pee, decrease BV

Question 12

Collecting Duct
Part of the nephron?
* Each duct collects filtrate from several nephrons for final modification
Collecting ducts merge as they descend deeper in the medulla to form about … terminal ducts, which empty at a …

They are lined with simple squamous epithelium with receptors for …
When stimulated by …, these cells will insert … channel proteins into their membranes

• These channel proteins allow … to readily pass from the duct lumen through the cells and into the interstitial spaces to be recovered by the vasa recta

This process allows for the recovery of … from the … back into the …

In the absence of …, these channels are not inserted into the plasma membrane, which in turn … to readily cross and results in …

Answer 12

Collecting Duct
Part of the nephron? - NO
* Each duct collects filtrate from several nephrons for final modification
Collecting ducts merge as they descend deeper in the medulla to form about 30 terminal ducts, which empty at a papilla

They are lined with simple squamous epithelium with receptors for anti- diruretic hormone (ADH)

When stimulated by ADH, these cells will insert aquaporin channel proteins into their membranes
* These channel proteins allow water to readily pass from the duct lumen through the cells and into the interstitial spaces to be recovered by the vasa recta

This process allows for the recovery of large amounts of water from the filtrate back into the blood

In the absence of ADH, these channels are not inserted into the plasma membrane, which in turn does not allow water to readily cross and results in water being excreted in the form of dilute urine