BIOS5130 Human Physiology and Disease - The Kidneys

Flashcards covering key vocabulary and concepts related to kidney anatomy, physiology, and function as presented in the lecture notes.

Kidneys

Regulate ECF volume, blood pressure, osmolarity, ion balance, pH, waste excretion, and hormones.

Urinary System Anatomy

Includes gross anatomy, nephron anatomy, Bowman’s capsule, Proximal tubule, Loop of Henle, distal tubule, collecting ducts, and renal pelvis.

Kidney Function Overview

Filtration, Reabsorption, Secretion, Excretion, Micturition

Kidneys Location

Located retroperitoneally at the level of the lower ribs.

Kidney Structure

Divided into an outer cortex and an inner medulla.

Nephron

Functional unit of the kidney, consisting of small tubes and associated blood vessels; modifies fluid content to produce urine.

Filtration

Fluid from blood into the lumen of the nephron at the renal corpuscle; filtered plasma is called filtrate.

Reabsorption

Materials in the filtrate are passed back into the blood, occurring with peritubular capillaries.

Secretion

Material from blood into the lumen of the tubule, occurring with peritubular capillaries.

Filtrate at Renal Corpuscle

Almost identical to plasma (180 L/day, 300 mOsm).

Filtration Fraction

Percentage of renal flow that filters into the tubule; only 20% of plasma is filtered.

Renal Corpuscle Filtration Barriers

Glomerular capillary endothelium, basement membrane, and podocytes.

Glomerular Filtration Rate (GFR)

Volume of fluid filtered per unit time, influenced by net filtration pressure and filtration coefficient.

Myogenic Response

Intrinsic ability of vascular smooth muscle to respond to pressure changes in the kidneys.

Tubuloglomerular Feedback

Paracrine control in the kidneys where macula densa cells detect NaCl and granular cells secrete renin.

Juxtaglomerular Apparatus (JGA)

Consists of macula densa and granular cells; important for paracrine signaling and GFR regulation.

Transepithelial Transport

Substances cross apical and basolateral membranes of tubule epithelial cells.

Paracellular Pathway

Substances pass through the cell–cell junction between two adjacent cells.

Sodium-Linked Reabsorption

Active transport of Na+ coupled with symport of glucose, amino acids, and other organic molecules.

Transport Maximum (Tm)

Transport rate at saturation; affects reabsorption of substances like glucose.

Proximal Convoluted Tubule (PCT)

Most substances are reabsorbed here (e.g., 65% Na+), reducing filtrate volume to 25%.

Loop of Henle Function

Creates an osmotic gradient in the medulla, enabling variable reabsorption of water and solutes.

Countercurrent Exchange

Vasa recta removes water leaving the loop of Henle maintaining the osmotic gradient.

Secretion Definition

Active movement of molecules from extracellular fluid into nephron lumen, important for K+ and H+ regulation.

Organic Anion Transporter (OAT)

Transporter family with broad specificity; substrates compete to bind.

Clearance Definition

Rate at which a solute disappears from the body by excretion or metabolism; used to measure GFR.

Inulin Clearance

Equals GFR because it is filtered freely but not absorbed or secreted.

Micturition

Process of urination, controlled by internal and external sphincters and a spinal reflex.