Kidney and Renal Physiology Lecture Review

A comprehensive set of practice flashcards covering kidney anatomy, glomerular filtration, renal blood flow regulation, and tubular transport mechanisms based on the lecture transcript.

What are the five main functions of the kidney?

a) Homeostasis, b) Regulation of arterial blood pressure, c) Excretory function, d) Endocrine secretion, and e) Metabolic function (gluconeogenesis and drug degradation).

Which endocrine substance secreted by the kidney stimulates erythropoiesis?

Erythropiotin.

What is the significance of the Juxta-medullary nephron compared to the Cortical nephron?

The Juxta-medullary nephron plays a major role in the counter current system and urine concentration, while the cortical nephron plays a minor role.

What are the three components of the Juxta-glomerular apparatus (JGA)?

Macula densa, Extra-glomerular cell (Lacis cell), and Juxtaglomerular granular cell.

What is the specific function of the Macula densa?

It acts as a chemoreceptor to monitor or sense $Nacl$ in urine.

What is the enzyme sequence for the production of Angiotensin II?

Renin converts angiotensinogen into angiotensin I, which is then converted into angiotensin II by Angiotensin converting enzyme (ACE).

What are the three mechanisms by which Angiotensin 2 causes salt and water retention in the kidneys?

Direct effect on the proximal tubule and an indirect effect on the distal tubule by stimulating aldosterone secretion from the adrenal cortex.

What are the nervous stimuli for renin release?

Sympathetic stimulation of beta 1 receptors on juxta glomerular cells.

Why does the diameter difference between afferent and efferent arterioles favor filtration?

The diameter of the efferent arteriole is smaller than the afferent, which favors high hydrostatic pressure in the glomerular capillary.

What is the normal value for Renal Blood Flow (RBF)?

$1200\,mL/min$ (or $4\,ml/min/gm$ of renal tissue).

The intrinsic regulation (autoregulation) of RBF is effective within which range of Arterial Blood Pressure (ABP)?

From $80$ to $180\,mmHg$.

Describe the Myogenic mechanism of RBF autoregulation.

$\uparrow ABP \rightarrow \uparrow RBF \rightarrow$ stretch of vessel wall $\rightarrow \uparrow Ca^{+2}$ influx $\rightarrow$ contraction of smooth muscle $\rightarrow$ V.C $\rightarrow \downarrow RBF$ to normal.

What size and molecular weight (M.W) criteria prevent substances from being filtered at the glomerulus?

Size $> 36\,A$ and M.W $> 70.000$.

What are the three layers of the filtration membrane?

Capillary endothelium, Basement membrane, and Bowman's capsular epithelium (podocytes).

What is the normal Glomerular Filtration Rate (GFR)?

$125\,mL/min$ (or $180\,L/day$).

What is the formula for GFR according to the starling principle?

$GFR = Kf (GP - BP - G\Pi)$ (where GP is Glomerular Hydrostatic Pressure, BP is Bowman Hydrostatic Pressure, and $G\Pi$ is Glomerular Osmotic Pressure).

What effect does vasoconstriction of the efferent arteriole have on RPF and GFR?

It decreases RPF, increases GFR, and increases the Filtration Fraction (FF).

What is the primary site for the reabsorption of essential nutrients like glucose and amino acids?

The convoluted segment (Pars convoluta) of the Proximal Tubule.

Which segment of the Loop of Henle is permeable to water but impermeable to solutes?

The Descending Loop of Henle (DLH).

Why is the Thick Ascending Loop of Henle called the 'diluting segment' of the nephron?

Because it reabsorbs solutes (via $Na^{+} - K^{+} - 2CL$ co-transport) without reabsorbing water, making the fluid leaving it hypotonic ($150-200\,m.osmol/L$).

What are the two specific cell types in the late distal tubule/collecting ducts and their functions?

1) Principle cell (reabsorbs $Na$ and water, secretes $K$) and 2) Intercalated cell (regulates blood PH).

What is the renal plasma threshold for glucose in venous blood?

$180\,mg/dl$.

Define 'Transport maximum (Tm)'.

The maximum amount of a substance that the tubular cells can transport within a given time due to carrier saturation.

Which hormone increases sodium reabsorption from the distal nephron?

Aldosterone.

What is the percentage of filtered water reabsorbed daily by the kidneys?

More than $99\%$ (out of $180\,L$ filtered, $178.5\,L$ is reabsorbed).