Module 15: Renal System Exam

Why does the glomerulus have high blood pressure?

Arterioles are high-resistance vessels and afferent arterioles have larger diameters than efferent arterioles

What is key for filtration?

High blood pressure

What does lower blood pressure in the Arteriole do?

Slows flow → maximal ability to reabsorb

What do the plasma proteins in the glomerulus do?

Cause colloid osmotic pressure → partially counteracts the HP

What makes up the renal corpuscle?

Bowman’s capsule and glomerulus

What happens when GFR is to high?

Needed substances cannot be re-absorbed quickly enough and are lost in the urine

What happens when the GFR is too low?

Everything is re-absorbed, including wastes that are normally disposed of

What does Renin in the RAAS Pathway activate?

Angiotensinogen into Angiotension I

What does the Angiotension-converting Enzyme (ACE) activate?

Angiotension I (ANG I) into Angiotension II (ANG II)

What happens when Angiotensin II (ANG II) targets the cardiovascular control center of the brain (CVVC)?

Promotes a sympathetic response to increase both heart rate and stroke volume (cardiac output)

What happens when Angiotensin II (ANG II) signals systemic arterioles?

Promotes vasoconstriction

What happens when Angiotensin II (ANG II) signals the Hypothalamus?

Triggers thirst reflex and releases vasopressin hormone

What happens when Angiotensin II (ANG II) signals the Adrenal cortex?

Releases the hormone Aldosterone→ promotes Na+ reabsorption in distal convoluted tubule (DCT)

What does blood pressure medications called ACE (Angiotension-converting enzyme) inhibitors do?

Blocks ACE so you don’t get ANG II, no longer have ability to raise blood pressure. Effective for people with elevated systemic blood pressure

What does the RAAS pathway hormone cascade ultimately cause?

An increase in blood volume and increase in blood pressure

What is the initial trigger of the RAAS Pathway?

Low blood pressure

If the filtrate is traveling through the tubular elements too fast what happens?

The macula densa cells detect this, they release a paracrine signal that targets smooth muscle of afferent arteriole→ promotes vasoconstriction, lowers glomerular HP, thus lowers filtration rate

How does smooth muscle respond when is it stretched (due to HP in the afferent arteriole)?

Constricting → myogenic contraction (this will lower glomerular HP)

What happens if the filtration rate is too slow?

1.Macula densa cells respond by releasing a paracrine signal that targets afferent arterioles leading to release of Renin 2.Granular cells have mechanoreceptors that release Renin 3.Sympathetic NS release Renin

What two things happen when macula densa cells release a paracrine signal targeting afferent arterioles (filtration rate too slow)?

Smooth muscle promotes vasodilation and target granular cells to release Renin

What happens to the substance when inulin clearance is less 125mL/min?

Substance is reabsorbed

What happens to the substance when the inulin clearance is more than 125mL/min?

Substance is secreted

What happens when your inulin clearance is under 60mL/min?

Indicates a renal disease

What happens when your inulin clearance is under 15mL/min?

Indicates renal failure

What are some triggers that cause the adrenal cortex to release Aldosterone?

Low Na+ concentration in the plasma and high K+ concentration in the plasma

What happens to your levels when you’re hypoventilating?

CO2 ⬆ so you favor the forward reaction [H+] ⬆ pH⬇ acidosis

What 3 things mitigate pH homeostasis?

Buffers, ventilation, and renal regulation

What happens to your levels when you are hyperventilating?

CO2 ⬇ and favor reverse [H+] ⬇ and pH ⬆ alkalosis

Is the respiratory system compensating for metabolic issues or respiratory issues?

Metablic issues

Is the renal system compensating for metablic issues or respiratory issues?

Respiratory issues

What is the renal system doing during respiratory acidosis CO2 ⬆H+⬆?

In the nephron: Lowers H+ levels→secretion and increases HCO3- levels(increasing buffering capacity)→ reabsorb

What is the renal system doing when you have respiratory alkalosis CO2⬇ H+⬇?

In the nephron: increase H+ levels→reabsorb and decrease HCO3- levels(decrease buffering capacity)→secrete

What are two ways to trigger renin release intrinsically to nephron?

Absence of stretch detects by granular cells and slow GFR detected by macula densa cells

Under what circumstances does the Renin-Angiotensin-Aldosterone pathway get activated?

Decreased blood volume and decreased blood pressure

What role does the liver play in the Renin-Angiotensin-Aldosterone Pathway?

Synthesizes and releases Angiotensinogen

Describe 4 phycological effects that activation of the Renin-Angiotensin-Aldosterone Pathway has on an individual.

1.Cardovascular control center of brain (CVCC)→ promotes sympathetic response to increase cardiac output. 2.systemic arterioles→promotes vasoconstriction 3.hypothalamus→trigger thirst reflex and source of vasopressin, targets collecting duct to promote water reabsorption 4.Adrenal Cortex→releases Aldosterone, promotes Na+ reabsorption in DCT

When aldosterone causes sodium reabsorption, why doesn’t water automatically follow?

The distal convoluted tubule epithelium is impermeable to water without vasopressin

How does the nephron’s counter-current exchanger work?

Flow of the filtrate in the tubular elements of the Loop of Henle flow in the opposite direction of the blood flow in the vasa recta/capillaries, allowing for maximal reabsorption (efficiency), as material moves down concentration gradients

Why are the 3 triggers to initiate vasopressin release?

Osmolarity greater than 280mOsM, decreased atrial stretch due to low blood volume, and decreased blood pressure

How would a person with metabolic alkalosis re-establish pH homeostasis

Respiratory compensation occurs through ventilation. They will experience hypoventilation. This increases the CO2 which results in increased H+

In severe dehydration or blood loss, what would be the levels of ADH and what would be the urine flow rate?

ADH - high; low urine flow rate (0.25 ml/min)

In a respiratory acidosis the kidney would do what?

Reabsorb bicarbonate and secrete hydrogen ions