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Block 4
Urinary System
| Question | Answer |
|---|---|
| What are the components of the urinary system? | Kidneys, ureters, urinary bladder and urethra |
| What are the functions of the urinary system? | Eliminates metabolic waste products, regulates fluid and electrolyte balance, produces renin and erythropoietin |
| What is the functional unit of the kidney? | NEPHRON |
| What are the two parts of the nephron? | Renal corpuscule and tubular part |
| Main function of the renal corpuscle? | Filtration |
| Main function of the tubular part? | Absorption and secretion |
| The renal corpuscle consists of what two parts? | Glomerulus and glomerular (Bowman's) capsule |
| The glomerulus consists of what? | Tuft of capillaries |
| The internal layer of Bowman's capsule does what? | Envelopes the capillaries of the glomerulus |
| The outer layer of Bowman's capsule does what? | Defines the external limits of the renal corpuscle |
| The space between the internal and outer layers of Bowman's capsule is called what? | The urinary space |
| The vascular pole of the renal corpuscle has what orientation with respect to arterioles? | Afferent arteriole enters and the efferent arteriole exits |
| What happens to the afferent arteriole in Bowman's capsule? | It branches into the capillaries of the glomerulus then the capillaries merge back to form the efferent arteriole. |
| The urinary pole of the renal corpuscle is the beginning of what? | The tubular part of the nephron |
| The urinary space connects to what? | The lumen of the proximal convoluted tubule |
| The outer (parietal) layer of the Bowman's capsule consists of what type of epithelium? | Simple squamous |
| The inner (visceral) layer of the Bowman's capsule consists of what epithelium? | Podocytes (highly specialized cell layer) |
| Each podocyte gives rise to several what? | Primary processes |
| Primary processes give rise to what? | Secondary processes (pedicles or foot processes) |
| How do secondary processes interact with the capillaries? | They interdigitate and embrace the capillaries |
| Filtration slits are located where? | In between adjacent secondary processes of the podocytes |
| What are Glomerular capillaries? | Fenestrated endothelial cells, no diaphragm |
| In the renal corpuscle, what lies between the capillary endothelium and the podocytes? | Basement membrane |
| The basement membrane serves what purpose? | Filtration barrier between the blood and the urinary space (both a physical barrier and a charge barrier) |
| The chemical composition of the glomerular filtrate is similar to what and does not contain any what? | Plasma, protein |
| How much filtrate is produced every minute? | 125 ml (only yield 1 ml of urine) |
| What cells are within the capillary tuft adhering to the capillary walls? | Mesangial cells |
| Mesangial cells provide what for the glomerulus? | Support (they also synthesize extracellular matrix and endocytose molecules trapped in the basement membrane) |
| What important function does mesangial cells provide for the glomerulus? | They are contractile cells and control blood flow through the glomerulus |
| Mesangial cells have receptors for what? | Angiotesin II (causes contraction and decreased blood flow) and atrial naturetic factor (causes relaxation and increased blood flow) |
| The proximal convoluted tubule is connected to the renal corpuscle where? | The urinary pole |
| The proximal convoluted tubule consists of what epithelium? | Simple cuboidal |
| Apical canaliculi of the proximal convoluted tubule does what? | Increases the capacity to absorb macromolecules, absorbs all glucose and amino acids, 85% of NaCl and water |
| The proximal convoluted tubules secretes what? | Creatinine, organic acids/bases from the blood |
| What are the two groups nephrons are divided into? | Cortical nephrons (short loops) and juxtamedullary nephrons (long loops the extend into the medulla) |
| The long loops of the juxtamedullary nephrons establish what? | Osmotic gradient that is present on the medulla |
| The osmotic gradient that is present in the medulla makes it possible to do what? | Produce hypertonic urine and conserve water |
| The osmotic gradient in the medulla runs from near __________ at the base of the medulla to _________ at the tip. | Isoosmotic, hyperosmotic (4 times plasma) |
| The osmotic gradient of the medulla is established by what? | The permeability of the thin descending and thin ascending limbs to water and NaCl. |
| What does epithelium does the distal convoluted tubule consist of? | Simple cuboidal |
| How does the distal convoluted tubule differ from the proximal convoluted tubule? | No brush border, no apical canaliculi and they have smaller cells |
| What occurs at the distal convoluted tubule? | Absorbs Na and secretes K (aldosterone dependent) also secretes H+ and ammonium (acid-base balance) |
| The course of the distal convoluted tubule leads it back to where? | The vascular pole of its parent renal corpuscle |
| The juxtaglomerular apparatus is located where? | The beginning of the distal convoluted tubule |
| What are the three cells of the juxtaglomerular apparatus? | Cells of the macula densa, JG cells, extraglomerular mesangial cells (lacis cells) |
| The macula densa is considered what? | A modified segment of the distal convoluted tubule |
| Cells of the macula densa are sensitive to what? | The ionic content and water volume of the tubular fluid |
| What are JG cells? | Modified smooth muscle cells of the afferent arteriole |
| What is absent from the arteriole of the juxtaglomerular apparatus? | Internal elastic lamina |
| JG cells secrete what? | RENIN |
| The juxtaglomerular apparatus activates what? | Renin-angiotensin-aldosterone system |
| Macula densa cells signal JG cells to secrete what? | Renin |
| Angiotensin II stimulates the adrenal cortex to secrete what? | Aldosterone |
| What connects a distal convoluted tubule to a collecting duct? | Collecting tubule |
| As collecting ducts become more distal they transition from what to what? | Simple cuboidal to columnar |
| Collecting tubules/ducts are lined by what two cell types? | Light cells (located throughout the duct) and dark cells |
| Dark cells of collecting ducts secrete what? | H+ or bicarbonate |
| Collecting ducts become permeable to water in the presence of what? | ADH |
| The renal artery branches to form what? | INTERLOBAR arteries (located between medullary pyramids) |
| Interlobular form what at the corticomedullary junction? | Arcuate arteries |
| Arcuate arteries give off what at right angles in the cortex that are perpendicular to the renal capsule? | INTERLOBULAR arteries |
| Interlobular arteries give off what that enters the renal corpuscles? | Afferent arterioles |
| Afferent arterioles divide into what? | Capillaries of the glomerulus |
| Capillaries of the glomerulus merge in to what? | Efferent arteriole |
| Efferent arterioles branch into what? | Peritubular capillary network |
| Efferent arterioles from the juxtamedullary glomeruli forms what? | Vasa recta |
| What is the vasa recta? | Long straight vessels that descend alongside the loop of Henle into the medulla |
| The vasa recta maintains what? | The osmotic gradient of the medulla |
| Cortical capillaries drain into what? | INTERLOBULAR veins |
| Interlobular veins and medullary veins drain into what? | Arcuate veins |
| Arcuate veins drain into what? | INTERLOBAR veins |
| Interlobar veins drain into what? | Renal vein |
| Capillaries from the outermost cortex and renal capsule drain into what? | Stellate veins |
| Stellate veins drain into what? | INTERLOBULAR veins |
| Once urine leave the collecting duct at the renal papillae, what happens to it? | It is no longer modified and enters the ureter |
| The lining of the minor calyces, major calyces, renal pelvis and ureter is what type of epithelium? | Transitional epithelium (urothelium- essentially impermeable to salts and water) |
| The ureter has two muscle layers, what are they? | Inner loose spiral layer (longitudinal) and and outer tight spiral layer (circular) |
| Adventitia consists of what? | Retroperitoneal adipose tissue, vessels and nerves |
| At the bladder neck muscles form a ring-like arrangement around the opening of the urethra called what? | Internal urethral sphincter |
Created by:
shuckybean