26-Urinary System Flashcards
Functions of urinary system - 4
Regulation of blood volume and composition
Production of waste urine
Transport of urine to bladder
Discharge of urine from body
Components of urinary system - 4
Kidneys
Ureters
Urinary bladder
Urethra
Kidney functions - 6
Regulation of blood ionic composition - Na, K, Ca2, HPO4
Regulation of blood pH
Regulation of blood volume
Regulation of blood pressure
Regulation of blood osmolarity
Production of calcitriol and erythropoietin
External kidney anatomy, 3 layers, 1 indentation
Hilum is indentation
Superficial - renal fascia
Middle - adipose capsule
Deep - renal capsule
Internal kidney anatomy - 5
Parenchyma includes these 3: Renal cortex
Renal medulla
Pyramids - wide base to cortex, narrow apex is renal papilla
Papilla feed minor calyces, which feed 2-3 major calyces
Renal sinus contains renal pelvis, calyces, blood vessels, nerves
Kidneys use how much oxygen
25%
Kidney blood supply - 3
Glomerulus ball of capillaries, separates blood and filtrate
Surrounded by glomerular/Bowman’s capsule
Efferent arteriole takes blood away, smaller than afferent
Nephron - 2 parts, 2+3 subparts
Renal Corpuscle - glomerulus and glomerular capsule
Renal Tubules - proximal convoluted tubules, distal convoluted tubules (PCT/DCT), loop of Henle
Types of Nephrons - 2
Cortical - 80%, short loops of Henle mostly in cortex
Juxtamedullary - 20%, long loops of Henle mostly in medulla, loops near vasa recta arterioles, loops have thick and thin parts
Nephron histology - 6
Fenestrated capillaries
Glomerular capsule has visceral, parietal layers
Parietal forms outer wall of capsule, into tubule
Visceral modified simple squamous podocytes, foot like projections form slits between for filtration
Bowman’s space between, gets filtrate
Juxtaglomerular apparatus - 3
End of ascending Henle forms macula densa against afferent arteriole
Afferent arteriole at macula has modified smooth muscle, JuxtaGlomerular (JG) cells
JG apparatus regulates blood pressure in kidney, secretes renin
Filtering is 3 step process
Glomerular filtration
Tubular reabsorption
Tubular secretion
Filtration fraction
Fraction of blood plasma that becomes glomerular filtrate. About 1/4.
Glomerular Membrane filtration barriers - 3
Epithelial cells - large fenestrations
Basal lamina - negative charge
Pedicels - filtration slits
Allows water, glucose, vitamins, minerals, amino acids, very small proteins, ammonia, urea, ions. NOT Albumin.
Glomerular Filtration Rate (GFR) - Too high, too low, controls - 2
Too High - Some needed substances not reabsorbed, lost in urine
Too Low - Reabsorb some waste, drugs
Intrinsic, Extrinsic
Intrinsic GFR - 2
Myogenic stretch reflex - too high causes arterioles to constrict
Tubuloglomerular feedback - juxtaglomerular cells use chemicals (ATP, NO) to vasoconstrict or vasodilate
Extrinsic GFR - 3
Neural Regulation - sympathetic
Hormonal - Renin Angiotensin Aldosterone
Angiotensin II - Potent vasoconstrictor, reducing GFR, also released by kidneys
Reabsorption/Secretion PCT - 4
Largest amount of solute & water reabsorbed in PCT - 100% glucose
Uses aquaporin-1
Solute reabsorption in PCT involves Na+
Secrete Urea and Ammonia PCT to tubular fluid
Reabsorption/Secretion Loop of Henle - 2
Thin descending has low permeability to ions and urea, high to water
Thin ascending impermeable to water, permeable to ions including Na & Cl
Reabsorption/Secretion late DCT and Collecting duct -
Na/Cl reabsorption via Na symporters
Principle Cells reabsorb Na, secrete K; Aldosterone increases Na/K pumps in these areas
Intercalated cells reabsorb K+ & bicarbonate, secrete H+
Solute reabsorption/secretion, water reabsorption varies based on body needs
Distal Nephron - 2 cell types, what they do
Principle Cells - vast majority, receptors for ADH, aldosterone
Intercalated cells - role in regulating pH
Amount of kidney function loss before symptoms
75% loss because kidneys can take on large loads
ADH in the Distal Tubule, how it works, % change
ADH causes Insert of aquaporin-2 into tubule membrane,
Less ADH, aquaporin-2 removed
1% change in plasma water concentration can cause ADH to be released by posterior pituitary
Concentrated Urine and countercurrent exchange/multiplication
Ions concentration highest in lowest part of LoH. Also in medulla surrounding LoH
Vasa Recta multiplies by looping ions around
If aquaporin-2 present in collecting duct in that area, concentration will pull water out of duct (osmosis)
This is how ADH causes more concentrated urine, conserves water in the body.
RAA Initial Pathway - 6
Decreased Na, dehydration, hemorrhage -> Lower blood volume/press
JG cells of kidneys make increased renin
Renin cleaves angiotensinogen from liver to angiotensin I
Angiotensin I to lungs Angiotensin Converting Enzyme ACE -> Angiotensin II
RAA Pathway second short
Angiotensin II vasoconstricts arterioles, raises blood pressure
RAA Pathway third through adrenal cortex
Angiotensin II OR increased K+ extracellular -> Adrenal cortex -> increased aldosterone
Aldosterone in kidneys causes increased absorption of Na+, water -> increased blood volume -> increased blood pressure
Ureter tissue layers 3 plus opening into bladder
Deep - mucosa transitional epithelium
Middle - Muscularis
Superficial - Adventitia
Oblique entry into bladder to prevent backflow
Trigone
triangle in bladder of two ureter openings, urethral opening
Muscles of bladder - 3
Detrusor - muscularis around bladder
Internal sphincter - involuntary smooth muscle
External sphincter - skeletal muscle, perineum
Layers of tissue for urinary bladder, plus word for urination
Mucosal - transitional epithelium
Muscularis - detrusor muscle
Adventitia - holds in place
Urination = micturition
Urethra - lengths, and 3 sections
Female - 4cm
Male - 20cm
- Prostatic
- Membranous
- Spongy
