Ch. 25 LEC - Urinary System

Lecture Exam 4

identify the major organs of the urinary system

kidneys, ureters, urinary bladder, urethra

summarize ALL functions of the kidney

• remove toxins and metabolic wastes

• remove excess ions from blood

• regulate blood volume, chemical composition, pH

• activate vitamin D (crucial for bone strength)

summarize the role of the urinary bladder

temporary storage reservoir for urine

summarize the function of the ureters

transport urine from the kidneys to the bladder

summarize the function of the urethra

transport urine out of the body

the kidneys perform gluconeogenesis during prolonged fasting. define gluconeogenesis

the metabolic process of creating new glucose from non-carbohydrate sources (e.g., lactate, amino acids, glycerol); ensures a stable blood sugar supply and energy

list the kidney’s endocrine duties

• secrete renin for blood pressure control

• secrete erythropoietin to stimulate RBC production

locate the kidneys

retroperitoneal (i.e., behind the peritoneum) in the superior lumbar region

describe the kidney’s layers of supportive tissue

1. renal fascia (anchoring outer layer of dense connective tissue)

2. perirenal fat capsule (cushion)

3. fibrous capsule (infection shield)

trace the journey of urine starting from the renal papilla to the ureter

renal papilla → minor calyx → major calyx → renal pelvis → ureter

the renal arteries deliver [FRACTION] ([NUMBER] mL) of cardiac output to the kidneys each minute

1/4, 1200

the kidney’s nerve supply is via [PARASYMPATHETIC/SYMPATHETIC] fibers from the renal plexus

sympathetic

trace the path of blood flow through renal blood vessels (starting with the aorta and ending with the inferior vena cava)

aorta → renal artery → segmental artery → interlobar artery → arcuate artery → radiate artery → afferent arteriole → glomerulus → efferent arteriole → peritubular capillaries and vasa recta → radiate vein → arcuate vein → interlobar vein → renal vein → inferior vena cava

define the nephron

the structural and functional unit that forms urine (1 million per kidney) consisting of a renal corpuscle and a renal tubule

trace the path of filtrate in the nephron (starting with renal corpuscle and ending with collecting duct)

renal corpuscle → proximal convoluted tubule → descending loop of Henle → ascending loop of Henle → distal convoluted tubule → collecting duct

name the structures that make up the renal corpuscle of the kidney’s nephron

glomerulus (capillaries) and its glomerular capsule

identify the histology of the glomerulus and its function

fenestrated glomerular endothelium allows filtrate from plasma to enter the glomerular capsule while ensuring RBCs stay in the blood vessel

name the different types of nephrons

cortical and juxtamedullary

true/false: juxtamedullary nephrons make up 85% of nephrons in the kidney

false — cortical nephrons make up 85% of nephrons in the kidney

contrast the location of cortical and juxtamedullary nephrons

• cortical nephrons: renal corpuscle sits high in the renal cortex AND loop of Henle barely dips into the medulla

• juxtamedullary nephrons: renal corpuscle sits close to the corticomedullary junction AND loop of Henle reaches deep into medulla and towards the renal papilla

contrast the function of cortical and juxtamedullary nephrons

• cortical nephrons: standard blood filtration, waste removal, and general fluid-electrolyte regulation

• juxtamedullary nephrons: create concentrated urine to save water during dehydration

contrast the length of Loops of Henle between the cortical and juxtamedullary nephrons

cortical nephrons have SHORT while juxtamedullary nephrons have LONG loops of Henle

contrast the blood supply between cortical and juxtamedullary nephrons

• cortical nephrons: surrounded by peritubular capillaries

• juxtamedullary nephrons: surrounded by vasa recta

trace the blood flow through the renal corpuscle

afferent arteriole → glomerulus → efferent arteriole

the glomerulus is specialized for _

filtration

identify the reason why the glomerulus has high blood pressure

• the efferent (away) arterioles are smaller in diameter than afferent (toward) arterioles

• arterioles are high-resistance vessels in general

peritubular capillaries:

• [LOW/HIGH] pressure, porous capillaries adapted for [FILTRATION/ABSORPTION]

• arise from [AFFERENT/EFFERENT] arterioles

• cling to adjacent renal tubules in [CORTEX/MEDULLA]

• empty into [ARTERIOLES/VENULES]

low, absorption, efferent, cortex, venules

vasa recta:

• [SHORT/LONG] vessels parallel to [SHORT/LONG] loops of Henle

• arise from [AFFERENT/EFFERENT] arterioles of [CORTICAL/JUXTAMEDULLARY] nephrons

• function: assist in the formation of concentrated urine

long, long, efferent, juxtamedullary

how does the high-resistance nature of the afferent and efferent arterioles affect the kidneys?

causes blood pressure to decline from 95 mmHg to 8 mmHg in kidneys

define juxtaglomerular apparatus (JGA)

a specialized structure in each nephron that is critical for regulating filtrate formation and blood pressure; located where the distal portion of the ascending Loop of Henle meets the afferent arteriole

name the cells involved in the juxtaglomerular apparatus (JGA)

granular cells (JG cells), macula densa cells, and extraglomerular mesangial cells

a part of the juxtaglomerular apparatus (JGA), [CELL TYPE] acts as mechanoreceptors that sense blood pressure

granular cells (JG cells)

identify the histology and secretion of granular (JG) cells of the JGA

smooth muscle that secretes renin

a part of the juxtaglomerular apparatus (JGA), [CELL TYPE] acts as chemoreceptors that sense NaCl content of filtrate

macula densa

extraglomerular mesangial cells are interconnected with gap junctions. what is the function of extraglomerular mesangial cells’ function in the JGA?

to pass signals between macula densa and granular (JG) cells