Anatomy and Physiology of the Renal System Notes

Contents

Osmosis High-Yield Notes

This Osmosis High-Yield Note provides an overview of Anatomy and Physiology of the Renal System essentials. All Osmosis Notes are clearly laid-out and contain striking images, tables, and diagrams to help visual learners understand complex topics quickly and efficiently. Find more information about Anatomy and Physiology of the Renal System:

Renal system anatomy and physiology

NOTES NOTES ANATOMY & PHYSIOLOGY RENAL ANATOMY & PHYSIOLOGY osms.it/renal-anat-phys RENAL SYSTEM ▪ Two kidneys ▫ Filter the blood from harmful substances ▫ Regulate blood pH, volume, pressure, osmolality ▫ Produce hormones ▪ Located between T12, L3 vertebrae; partially protected by ribs 11, 12; behind peritoneal membrane (retroperitoneal) ▪ Right kidney slightly lower due to larger portion of the liver on right side ▪ Filter 150 liters of blood everyday; receive ¼ of cardiac output from renal arteries (from aorta) ▫ Renal arteries divide → segmental arteries → interlobar arteries (between renal columns) → arcuate arteries (cover bases of renal pyramids) → cortical radiate arteries (supply the cortex) → afferent arterioles (supply nephrons) ▪ Renal capsule (inner) ▫ Dense connective tissue ▫ Gives kidney shape Figure 57.1 Kidney placement in relation to ribs and vertebrae. MORPHOLOGY Renal hilum ▪ Indentation in the middle of each kidney ▪ Entry/exit point for ureter, arteries, veins, lymphatics, nerves Surrounding tissue (three layers) ▪ Renal fascia (outer) ▫ Dense connective tissue ▫ Anchors kidney ▪ Adipose capsule (middle) ▫ Fatty tissue ▫ Protects kidney from trauma 510 OSMOSIS.ORG Figure 57.2 Arterial bloodflow in the kidney.
Chapter 57 Renal Physiology: Anatomy & Physiology Renal cortex (outer portion) ▪ Outer cortical zone ▪ Inner juxtamedullary zone ▪ Renal columns project into the kidney, separating medulla Renal medulla (inner portion) ▪ 10-18 renal pyramids with pointy ends (renal papilla/nipples) towards center of kidney ▪ Renal lobes: renal pyramids including cortex above them ▪ Renal papilla → minor calyces → major calyces → renal pelvis → ureter Figure 57.3 Transverse cross-section showing retroperitoneal position of kidneys, surrounding tissue layers. Figure 57.4 Cross-section through kidney showing renal medulla, renal cortex, and urine flow through kidney. Nephron ▪ Functional unit of kidney (about one million in each kidney) ▪ Composed of renal corpuscle, renal tubule ▪ Blood filtration starts in renal corpuscle ▫ Includes glomerulus, a tuft of capillaries supplied by afferent arteriole, and Bowman’s capsule ▫ Blood flows into glomerulus → water, solutes (e.g. sodium) pass through capillary endothelium → through basement membrane → through epithelium → into Bowman’s space (becoming filtrate) ▫ Epithelium comprises podocytes wrapped around basement membrane; gaps called filtration slits allow small solutes through but block large proteins, red blood cells ▫ Blood leaving glomerulus enters efferent arteriole → divides into peritubular capillaries → these reunite into cortical radiate veins → arcuate veins → interlobar veins → renal veins → inferior vena cava OSMOSIS.ORG 511
Figure 57.5 Nephron anatomy. ▪ Filtrate from Bowman’s capsule enters renal tubule ▫ Made up of proximal convoluted tubule, descending/ascending limbs of nephron loop (loop of Henle), distal convoluted tubule, collection ducts (which send urine to minor calyces) ▫ Filtrate is further filtered by passing water, solutes between filtrate, blood in peritubular capillaries ▪ Blood pressure, glomerular filtration rate regulated by juxtaglomerular complex ▫ Located between distal convoluted tubule and afferent arteriole ▫ Contains three types of cells: macula densa, extraglomerular mesangial, juxtaglomerular (granular) cells Figure 57.6 Blood flow through nephron and venial bloodflow in kidney. 512 OSMOSIS.ORG
Chapter 57 Renal Physiology: Anatomy & Physiology ▫ Macula densa cells in distal convoluted tubule sense ↓ sodium/blood pressure → juxtaglomerular cells secrete renin → ↑ sodium reabsorption, constricting blood vessels → ↑ blood pressure via the renin–angiotensin–aldosterone system (RAAS) ▪ Urine from renal tubules enters minor calyces → major calyces → renal pelvis → ureter Bladder ▪ Bladder receives urine from ureter ▫ Urine enters at ureterovesical junctions ▫ Muscular walls fold into rugae as bladder empties ▪ Bladder wall contains multiple layers ▫ Transitional epithelium: allows bladder to distend while maintaining a barrier ▫ Detrusor muscle: helps with bladder contraction ▫ Fibrous adventitia: holds bladder loosely in place ▪ Located in front of rectum in biologicallymale individuals; in front of vagina, uterus, and rectum in biologically-female individuals ▪ Holds 750mL of urine ▫ Biologically-female individuals: slightly less due to crowding from uterus ▪ Contains smooth triangular region (trigone region) on bladder floor ▫ Bounded by two ureterovesical junctions and internal urethral orifice ▫ Highly sensitive to expansion → signals brain as bladder fills Figure 57.7 Cross-section through renal capsule showing juxtaglomerular complex. Figure 57.8 Bladder anatomy. Figure 57.9 Sagittal cross-section showing placement of bladder in relation to other organs. OSMOSIS.ORG 513
Figure 57.10 Coronal cross-section through bladder showing urethra anatomy. Urethra ▪ Drains urine from bladder ▪ Structured differently in biologically male and female people ▫ Starts at internal urethral orifice ▫ Male: passes through prostate (prostatic urethra), deep peritoneum (intermediate urethra), penis (spongy urethra); also used during ejaculation (semen enters via seminal vesicles) ▫ Female: passes through perineal floor of pelvis, exits between labia minora (above vaginal opening but below clitoris) ▫ Detrusor muscle thickens at internal urethral orifice forming internal sphincter (involuntary control; controlled by autonomic nervous system; keeps urethra closed when bladder isn’t full) ▫ External sphincter is located at level of urogenital diaphragm in floor of pelvis (voluntary control; can be used to stop urination with kegel exercises) Urination ▪ Involves close coordination between nervous system and bladder muscles ▪ Bladder volume of > 300–400mL, sends signals to micturition center in spinal cord (located at S2 and S3) → micturition reflex causes contraction of bladder and relaxation of both sphincters ▫ Pontine storage center in pons of brain can be activated to stop micturition reflex ▫ Pontine micturition center can be activated to allow micturition reflex Figure 57.11 Signal pathways of micturition reflex. 514 OSMOSIS.ORG

Osmosis High-Yield Notes

This Osmosis High-Yield Note provides an overview of Anatomy and Physiology of the Renal System essentials. All Osmosis Notes are clearly laid-out and contain striking images, tables, and diagrams to help visual learners understand complex topics quickly and efficiently. Find more information about Anatomy and Physiology of the Renal System by visiting the associated Learn Page.