Renal System Anatomy and Functions Quiz

Renal System Functions

• Excretion: removes organic waste from the body
• Elimination: expels waste products from the body
• Homeostatic regulation: controls fluid balance, electrolytes, and pH levels
• Regulation of blood volume and blood pressure
• Regulation of electrolytes (ions)
• Maintaining blood pH levels
• Conserving valuable nutrients (glucose, amino acids)
• Excretion of metabolic waste (urea, uric acid)
• Production of Vitamin D for strong bones

Gross Anatomy of Kidneys

• Location: on either side of the vertebral column, the right kidney is slightly lower due to the liver's size
• Description: bean-shaped, reddish-brown organs in the retroperitoneal region
• Right kidney sits slightly lower than the left
• Large size of the right lobe of the liver

Kidney Anatomy

• Renal capsule: fibrous covering the kidney
• Hilum: medial entrance; transmits renal pelvis, ureter, blood vessels, and nerves
• Renal pelvis: upper expanded end of the ureter
• Renal pyramids: about a dozen, inner layer that are apex-projected into minor calyces
• Renal columns: separates renal pyramids
• Renal sinus: contains adipose tissue
• Renal papilla: apex of renal pyramids

Kidney Sectional Anatomy

• Cortex: outer layer
• Medulla: inner layer, composed of renal pyramids
• Renal pyramids: apex projects into minor calyces
• Minor calyces: group to form major calyces
• Major calyces: unite to form renal pelvis
• Renal artery: carries 20% of cardiac output posteriorly
• Renal vein: drains into the Inferior Vena Cava (IVC) anteriorly

Blood Supply of the Kidney

• Renal arteries: enter the renal sinus, branch into interlobar arteries
• Arcuate arteries: arch over the bases of the renal pyramids
• Interlobular arteries: branch to form the afferent arterioles

Nephron (Microscopic Structure)

• Glomerulus: capillary network
• Bowman's capsule: cup-shaped structure surrounding the glomerulus
• Afferent arteriole: brings blood into the glomerulus
• Efferent arteriole: carries blood away from the glomerulus
• Filtration membrane: separates blood from the filtrate ( Bowman's capsule). Allows small molecules to pass through.
• Renal tubule: long tube for urine formation and modification processes with the glomerular filtrate; composed of PCT, Loop of Henle, and DCT

Renal Tubule Components

• Proximal Convoluted Tubule (PCT): reabsorb water, ions, and organic nutrients
• Loop of Henle: further reabsorption of water (descending limb) and both sodium and chloride ions (ascending limb)
• Distal Convoluted Tubule (DCT): secretion of ions, acids, drugs, and toxins

Renal Corpuscle Components

• Bowman's capsule
• Glomerulus

Components and Functions of the Nephron

• Production of filtrate
• Reabsorption of water, ions, organic nutrients and all other filtered molecules

Juxtaglomerular Apparatus (JGA)

• Formed by cells of DCT and cells in afferent arterioles wall
• Macala densa (cells in DCT), cells of DCT, DCT closest to glomerulus
• Juxtaglomerular cells: smooth muscle fibers in the wall of afferent arteriole
• Secretion of renin and erythropoietin
• Regulation of blood pressure and glomerular filtration

Ureters

• 30cm long muscular tubes; renal pelvis enlarged part; funnel shaped funnel for urine
• Transitional epithelium; Smooth muscle layer; End at the posterior wall of the urinary bladder;

Micturition Reflex

• Bladder stretches as it fills
• Sends signals to parasympathetic nerves in spinal cord
• Brain is made aware of bladder filling
• Urinary bladder contraction
• Both the internal and external sphincters relax
• Urine expelled

Urine Formation and Composition

• Maintaining homeostasis by regulating volume and composition of blood
• Excretion of waste products (urea, creatinine, uric acid)
• Urea: breakdown of amino acids
• Creatinine: breakdown of creatine phosphate
• Uric acid: breakdown of ribonucleic acid (RNA)

Urine Physical Characteristics

• Volume: 1200ml/day (varies)
• Color: Yellow/amber but varies - usually transparent
• Turbidity: clear

Abnormal Urine Constituents

• Albuminuria: indicates increased permeability of filtering membranes
• Glycosuria: indicates diabetes mellitus, a metabolic disorder where blood sugar is elevated
• Hematuria: indicates a pathological condition
• Pyuria: indicates infection of urinary system
• Ketone bodies: indicates diabetes mellitus, starvation, or excessive fat intake

Hormonal Control of Kidneys (Major Hormones)

• Antidiuretic hormone (ADH): increased water reabsorption in collecting ducts
• Aldosterone: increases sodium reabsorption in DCT
• Atrial natriuretic peptide (ANP): increases sodium and fluid excretion and lowers blood volume/pressure