BIOL 4431: Chapter 14 Study Guide

These flashcards cover key concepts from Chapter 14 relevant to renal physiology, including kidney functions, nephron structure, urine production mechanisms, and the significance of ion regulation.

What are the five functions of the kidneys?

The kidneys filter blood, produce urine, regulate blood pressure, maintain electrolyte balance, and regulate acid-base balance.

What is the basic structure of a nephron and its main components?

A nephron consists of the glomerulus, proximal convoluted tubule, descending and ascending loop of Henle, distal convoluted tubule, and collecting duct.

What is glomerular filtration?

Glomerular filtration is the process by which the kidneys filter blood, allowing certain solutes like water, electrolytes, and waste products to pass into the nephron while retaining larger molecules.

What pressure forces are involved in net glomerular filtration pressure?

Net glomerular filtration pressure is the difference between glomerular hydrostatic pressure (which promotes filtration) and the forces opposing filtration, namely capsular hydrostatic pressure and blood colloid osmotic pressure.

What is GFR and how does vasodilation/vasoconstriction affect it?

GFR (glomerular filtration rate) is the rate at which blood is filtered through the glomeruli. Vasodilation of the afferent arteriole increases GFR, while vasoconstriction of the efferent arteriole also increases GFR, and vice versa.

How does the sympathetic nervous system affect GFR?

Activation of the sympathetic nervous system decreases GFR by causing constriction of afferent arterioles to redirect blood to vital organs during stress.

Where is the macula densa located and what is its function?

The macula densa is located in the distal convoluted tubule and is involved in sensing sodium chloride concentrations, thus regulating GFR intrinsically.

How is the macula densa connected to intrinsic regulation of GFR?

What leads to the release of renin by juxtaglomerular cells?

Renin is released in response to low blood pressure, low sodium concentrations, or sympathetic stimulation, initiating the renin-angiotensin system.

Define tubular reabsorption and which sections of the renal tubule are involved.

Tubular reabsorption is the process by which the renal tubule reabsorbs solutes and water back into the bloodstream, mainly occurring in the proximal convoluted tubule.

Why are Na+ and H20 coupled during tubular reabsorption?

Na+ and H2O are coupled due to osmotic pressure; the reabsorption of Na+ creates an osmotic gradient that facilitates the passive reabsorption of water.

What is the countercurrent multiplier system?

The countercurrent multiplier system is a mechanism that maintains a medullary osmotic gradient essential for concentrating urine, involving the interaction of the descending and ascending loops of Henle.

How does ADH contribute to urine concentration?

ADH (antidiuretic hormone) promotes water reabsorption in the collecting duct, utilizing the osmotic gradient created by the countercurrent multiplier to produce hyperosmotic urine.

What is tubular secretion and which sections of the renal tubule are involved?

Tubular secretion is the process by which additional substances are transported from the blood into the renal tubule, occurring primarily in the distal convoluted tubule and collecting duct.

Why is K+ ion regulation important?

K+ regulation is crucial for maintaining heart rhythm and muscle function, directly tied to Na+ reabsorption as both ions are involved in electrical gradients across cell membranes in the renal tubule.