Renal Hemodynamics and RAAS

Question 1

The Juxtaglomerular Apparatus is a complex feedback mechanism used by the kidney to ____

Answer 1

Autoregulate the GFR

Question 2

The thick segment of the ascending limb of the Loop of Henle becomes the ____ as it passes between the Afferent and Efferent Arterioles

Answer 2

Distal Tubule

Question 3

The JG Apparatus consists primarily of two types of specialized cells:

Answer 3

Juxtaglomerular Cells
Macula Densa

Question 4

Juxtaglomerular cells, sometimes called Granular cells, are ______ cells found in the wall of the Afferent and Efferent Arterioles adjacent to Bowman’s Capsule

Answer 4

specialized smooth muscle

Question 5

Juxtaglomerular cells contain granules full of the hormone ____

Answer 5

Renin

Question 6

The_____ is a region of specialized epithelium within the wall of the Distal Tubule immediately adjacent to the Afferent and Efferent Arterioles.

Answer 6

Macula Densa

Question 7

Macula Densa cells are a type of____ and are especially sensitive to the concentration of Sodium (technically NaCl) within the lumen of the tubule

Answer 7

Chemoreceptor

Question 8

Macula Densa cells are especially sensitive to the concentration of _____ within the lumen of the tubule.

Answer 8

Sodium (technically NaCl)

Question 9

Where do sympathetic nerve endings synapse in the Juxtaglomerular Apparatus?

Answer 9

on Afferent and Efferent Arteriole smooth muscle fibers.

Question 10

What do Mesangial cells do?

Answer 10

act primarily as support cells in the region where all these structures (of JA) come together.

Question 11

There are three main mechanisms that trigger Renin release from the Juxtaglomerular Cells

Answer 11

Physical
Electrical
Chemical

Question 12

Physical trigger for release of renin

Answer 12

Juxtaglomerular Cells in the walls of the Afferent Arterioles act as baroreceptors and respond to a drop in systemic blood pressure by releasing Renin directly into the blood

Question 13

Electrical trigger for the release of renin

Answer 13

Stimulation of the Sympathetic Nerve Fibers during a “fight or flight” situation causes Afferent and Efferent Arterioles to vasoconstrict (thereby briefly and acutely dropping GFR), as well as stimulating release of Renin by the Juxtaglomerular Cells.

Question 14

T/F Renin release is one mechanism by which BP increases

Answer 14

T

Question 15

Chemical trigger for renin release

Answer 15

• When Macula Densa cells sense a drop in Na and Cl concentration in the tubule, this is interpreted as a decrease in GFR, and the Macula Densa cells respond by secreting Prostaglandins.
• Renal prostaglandins act as a paracrine messenger by triggering Afferent Arteriole vasodilation (increasing glomerular pressure, GFR), and by triggering Juxtaglomerular cells to release Renin.

Question 16

The JAS is is also the beginning point of the _____

Answer 16

Renin-Angiotensin-Aldosterone System (RAAS)

Question 17

The RAAS ultimately results in ____ and ____ in the tubules of the kidneys

Answer 17

peripheral vascular constriction; fluid/electrolyte retention

Question 18

The end-goal and purpose of the RAAS is to _____

Answer 18

increase systemic blood pressure when blood pressure and/or GFR are low

Question 19

When the peptide hormone Renin is released from the Juxtaglomerular Cells in the kidney, it enters ____

Answer 19

systemic circulation (meaning it goes everywhere)

Question 20

Angiotensinogen is an ____ peptide hormone that is secreted continuously by Hepatocytes in the liver

Answer 20

inactive

Question 21

While in circulation, Angiotensin I comes in contact with ____, which is largely found in pulmonary capillaries as well as other endovascular cells

Answer 21

Angiotensin Converting Enzyme (ACE)

Question 22

ACE enzymatically slices Angiotensin I, converting it to the very active and potent _____.

Answer 22

Angiotensin II

Question 23

When Renin comes in contact with Angiotensinogen, it enzymatically slices ____, converting it to mildly active Angiotensin I

Answer 23

Angiotensinogen

Question 24

How does Angiotensin II work to increase arterial blood pressure?

Answer 24

One mechanism is by acting as a potent vasoconstrictor, causing contractions of peripheral vascular smooth muscle, which increases peripheral resistance, thereby increasing blood pressure.

Question 25

Angiotensin II can also act directly on the ____ system of the kidney to increase Sodium reabsorption

Answer 25

tubular

Question 26

Angiotensin II also causes ___ of the Efferent Arterioles

Answer 26

vasoconstriction

Question 27

Angiotensin II also stimulates secretion of ____

Answer 27

Antidiuretic Hormone (also known as Arginine Vasopressin or AVP)

Question 28

Angiotensin II also stimulates secretion of ____ from the Adrenal glands

Answer 28

Aldosterone

Question 29

Aldosterone works primarily at the distal convoluted tubule and collecting tubules of the kidney to increase ___ secretion and ___ reabsorption.

Answer 29

K+; Na+ (& water)

Question 30

Renal Artery Stenosis is a _____ of the renal arteries that supply blood flow to the kidneys.

Answer 30

narrowing

Question 31

Two common classes of medications that work by influencing the RAAS are

Answer 31

Angiotensin Converting Enzyme Inhibitors (ACE-Is)
Angiotensin Receptor Blockers (ARBs)