Renal Lecture 1 Flashcards
Topic: Renal System CH 25 and 26
Kidneys role:
Balance Salt & Water
Regulate Ions
Maintain pH
Excrete Wastes
Produce EPO
Produce Renin
Activate Vitamin D
Filter 200L/day.
Kidneys: Make urine.
Ureters: Transport urine to bladder.
Bladder: Stores urine.
Urethra: Excretes urine.
Dialysis: Filters blood in kidney failure.
O2 Monitoring: Low O2 increases EPO for RBCs.
Renin: Maintains blood pressure.
Renin: Enzyme that regulates blood pressure.
Renn: Digestive enzyme in babies (rennin), helps digest milk protein.
Kidneys:
Shape/Location: Bean-shaped, retroperitoneal (T12-L3).
Protection: Rib cage; right kidney lower (liver).
Size: ~150g, 12 x 6 x 3 cm.
Adrenal Glands: On top of kidneys.
See figure 25.3a
Kidneys: Same in both sexes.
Vulnerable: Can be damaged by impact.
Right Kidney: Lower due to space.
Blood Flow: Needed for filtration.
Adrenals: Regulate kidneys via hormones.
Behind the peritoneal cavity is where the kidneys are found.
Concave (renal hilum to renal sinus), with supportive layers:
Renal (fibrous) capsule: Barrier to damage, infections from spreading to kidney from other parts.
Perirenal fat capsule: Cushions, stabilizes.
Renal fascia: Anchors kidney/adrenal.
See diagram
Middle: Indentation.
Outside: Indentation.
Internal: Sliced kidney.
3 Layers (Out to In):
Renal Capsule: Infection protection.
Fat Capsule: Cushioning.
Renal Ptosis: Kidney drop (malnourished risk).
Internal Anatomy:
Cortex: Filtration & urine formation. outer
Medulla: Striped due to pyramids & columns.
Pelvis: Funnels urine to ureter via calices.
Muscle: Smooth muscle moves urine by peristalsis.
Urine Flow:
Papillae → calyces → pelvis → ureter → bladder.
Pyelonephritis is a kidney infection usually caused by a UTI spreading to the kidneys, leading to pain and potential damage.
Blood Filtration: Cortex, fenestrated capillaries.
Striped: Collecting ducts in pyramids.
Renal Columns: Blood vessels to cortex. Indentations of cortical tissue.
Calices: Urine pathway start.
Papillae: Ducts merge.
Peristalsis: Moves urine.
Pyelonephritis: Kidney infection, antibiotics.
See diagram on circulatory pathway through Kidney
Renal arteries: 1,200 ml/min (1/4 cardiac output).
the circulatory pathway through the kidney:
Renal Artery → Segmental Artery → Interlobar Artery → Arcuate Artery → Cortical Radiate Artery
Afferent Arteriole → Glomerulus (capiallaries) Efferent Arteriole → Peritubular Capillaries/Vasa Recta
Cortical Radiate Vein → Arcuate Vein → Interlobar Vein → Renal Vein
Aorta → Renal Artery → Segmental → Interlobar → Arcuate → Cortical Radiate
Afferent Arteriole → Glomerulus → Efferent Arteriole → Peritubular (reabsorb H2O/solutes)/Vasa Recta (concentrated urine)
Cortical Radiate Vein → Arcuate → Interlobar → Renal Vein → Inferior Vena Cava
Circulation of blood through the kidneys, showing how blood flows from the aorta into the kidneys, gets filtered through the glomerulus, and then returns to the inferior vena cava after waste removal and nutrient absorption. It highlights the process of filtration, reabsorption, and secretion within the kidneys.
Renal Arteries: Supply ~1/4 CO (~1.2 L/min).
Arteries & Veins: Pass between pyramids to cortex, drain same path.
Nerve Supply: Renal plexus (sympathetic) regulates blood flow.
Glomerulus: Filtration site, O2-rich blood.
Renal Plexus: Regulating what the kidneys do, regulating blood vessel diameter, so the sympathetic NS takes over not Parasympathetic nervous system. Regulate how quickly the blood is filtered?
Blood Filtration
Blood enters via renal artery → glomerulus filters blood → Bowman’s capsule.
Nephron Structure
PCT: Reabsorbs nutrients.
Loop of Henle: Water reabsorption.
DCT: Reabsorption & secretion.
Collecting Ducts: Concentrates urine.
Renal Anatomy
Striped: Collecting ducts in pyramids.
Renal Columns: Blood vessels between pyramids.
Calices: Collect urine from papillae.
Nephron Types
Cortical: Short Loop of Henle.
Juxtamedullary: Long Loop of Henle, for urine concentration.
Filtration components:
Filtration Components:
Glomerulus: Filters blood through capillaries.
Bowman’s Capsule: Collects the filtered fluid.
Renal Corpuscle: Glomerulus + Bowman’s Capsule.
Fenestrated Endothelium: Capillary wall with pores for fluid/small molecules.
Podocytes: Specialized cells with foot-like extensions.
Filtration Slits: Gaps between podocyte “feet” where filtration occurs.
Bowman’s Capsule:
Outer layer: Thin epithelial cells.
Inner layer: Podocytes.
Filtration Slits: Gaps between podocytes where fluid passes from capillary bed to lumen.
Most reabsorption happens at the PCT.
The Juxamedullary during times of dehydration, slow down filtration.
35% Juxa in Camels.
When organized, It has a long Loop of Henle for efficient water reabsorption, especially in times of dehydration.
Two types of nephron:
Two types of neprhons:
Cortical nephrons (about 85%) – mostly in the cortex.
- do most of filtration & reabsorption
Juxtamedullary nephrons (about 15%) 35% in camels – near the medulla, important for concentrating urine - key for water balance.
Kidney Filtration Process
Pathway:
PCT: Reabsorbs nutrients and water.
Nephron Loop:
Descending limb: Water reabsorption.
Ascending limb: Ion reabsorption.
DCT: Adjusts ions and water.
Collecting Duct: Final water and salt balance (principal cells and intercalated cells) - microvilli.
Papillary Duct: Drains into Minor Calyx.
Kidney Structure:
Renal Cortex: Glomerulus and tubules.
Renal Medulla: Nephron loops, collecting ducts.
Renal Pelvis: Collects urine.
Ureter: Transports urine.
Renal Corpuscle:
Glomerulus: Filters blood.
Capsule: Collects filtrate. visceral and parietal layer.
Arterioles:
Afferent: Brings blood in.
Efferent: Carries blood out.
Filtration Steps:
Blood filters into glomerular capsule.
PCT reabsorbs water, nutrients.
Nephron Loop reabsorbs water and ions.
DCT fine-tunes balance.
Collecting Duct finalizes water/salt balance.
Urine drains into Minor Calyx.
Cortical – salt; juxtamedullary – water
Camel – 35% juxtamedullary
Active transport of sodium by the cells of the ascending loop creates the high osmolality of the interstitial fluids in the medulla.
The proximal convoluted tubule (PCT) is where most reabsorption takes place.
Microcirculation of the Nephron
Glomerulus: Specialized for filtration; fed/drained by arterioles.
Afferent Arteriole: Larger diameter, brings blood in.
Efferent Arteriole: Drains blood, maintains pressure.
Peritubular Capillaries: Arise from efferent arterioles, drain into renal venules.
Vasa Recta:
Found in the renal medulla.
Maintains concentration gradient for water reabsorption.
The pons is the brain region where the micturition reflex originates.
To Increase Blood Pressure in the Glomerulus:
Slow down blood leaving the glomerulus: This increases pressure in the glomerulus, ensuring continued filtration.
Kidneys must keep working: They can’t be “turned off” – constant filtration is essential.
Vasa Recta (right side, lower part):
Plays a role in maintaining the renal medullary concentration gradient.
Helps regulate blood flow and supports efficient water reabsorption.
Juxtaglomerular Complex (JGC)
Location: Between early DCT and afferent/efferent arterioles.
Components:
Granular (JG) Cells: Secrete renin to regulate blood pressure, enlarged. Mechanor.
Macula Densa Cells: Monitor filtrate and adjust GFR, chemor and osmor.
Functions:
Regulate Filtration and Blood Pressure via renin secretion.
The macula densa cells monitor the NaCl content of the filtrate entering the distal convoluted tubule.
Macula Densa Cells: Monitor sodium levels in the filtrate and help adjust renal blood flow and GFR by signaling granular cells to release renin.
Granular Cells (Juxtaglomerular Cells): Secrete renin, which is involved in regulating blood pressure and the GFR through the RAAS system.
The macula densa cells and granular cells of the juxtaglomerular complex (JGC) release, respectively, vasoactive chemicals and renin. These chemical messengers lead to changes in vasomotor activity and Na+ reabsorption that affect the rate of filtrate formation and systemic blood pressure.
Micturition Pathways: Male vs. Female
Males:
Longer urethra (~20 cm).
Internal sphincter: Smooth muscle, involuntary.
External sphincter: Skeletal muscle, voluntary.
Females:
Shorter urethra (~4 cm).
Internal sphincter: Involuntary.
External sphincter: Voluntary.
Trigone
Trigone: Triangle in bladder formed by ureter and urethra openings; clinically important for UTIs.
Bladder Capacity
Normal bladder: 500 ml (can hold up to 1000 ml).
Sphincters
Internal: Smooth muscle (involuntary).
External: Skeletal muscle (voluntary).
Nephron: Functional Unit of the Kidney
Primary Functions:
Filtration: Removes waste and excess substances from blood.
Reabsorption: Returns needed substances to the bloodstream.
Additional Functions (A WET BED):
Acid-base balance
Water balance
Electrolyte balance
Toxin removal
Blood pressure regulation
Erythropoiesis regulation
Detoxification
Filtrate vs. Urine:
Filtrate: Plasma minus proteins.
Urine: Filtrate minus nutrients, essential ions, and most water.
Fluid Processing:
180 L filtered daily; 1.5 L (1%) excreted as urine.
Glomerular filtration: Blood is filtered to create a filtrate.
Tubular reabsorption: Useful substances are reabsorbed back into the blood.
Tubular secretion: Extra waste and ions are secreted into the filtrate for excretion.
Albumin is a protein in the blood that helps maintain osmotic pressure, regulate fluid balance, and transport various substances, including hormones, vitamins, and drugs.
Albumin is a protein in the blood that helps maintain osmotic pressure. Osmotic pressure is the force that pulls water back into the blood vessels from tissues, preventing too much fluid from leaking out. This helps maintain the balance of fluids in the body.
If the liver were making insufficient levels of albumin, which is the most important contributor to the blood’s osmotic pressure, the blood’s osmotic pressure would drop, leading to a rise in filtrate production.
The intermediate part of the urethra (membranous urethra) runs through the urogenital diaphragm, extending about 2 centimeters from the prostate to the beginning of the penis.
Which of the following is NOT one of the things that must happen for micturition to occur?
The external urethral sphincter must open.
The pontine storage center must be activated.
The internal urethral sphincter must open.
The detrusor muscle must contract.
Good job!
More information
The pons has two centers that participate in control of micturition being advised of bladder (stretching) fullness. The pontine storage center inhibits micturition, whereas the pontine micturition center promotes this reflex. Thus, it is the pontine micturition center that would need to be activated for micturition to occur.
Kidney Stones: Can block urine, treated by lithotripsy.
