unit iv: regulation urinary system chapter 24: pp. 885-891 chapter 23: pp. 847-856
TRANSCRIPT
Unit IV: RegulationUrinary System
Chapter 24: pp. 885-891
Chapter 23: pp. 847-856
Water Balance
• Total body water for 150 lb. male = 40L
• Fluid compartments
– 65% ICF
– 35% ECF
• 25% tissue fluid
• 8% blood plasma, lymph
• 2% transcellular fluid (CSF, synovial fluid)
Water Movement in Fluid Compartments
Osmosis Capillary filtration
Capillaries; Cells; or Lymphatic System
• Electrolytes play principle role in water distribution and total water content
Fluid Balance
Preformed water
Water Loss
• Loss varies greatly with environment and activity
– respiratory loss : with cold, dry air or heavy work
– perspiration loss : with hot, humid air or heavy work
• Sensible water loss– urine and abundant sweating
• Insensible water loss
– breath and cutaneous transpiration
• Obligatory water loss
– Expired air, cutaneous transpiration, sweat, feces, minimum urine output (400 ml/day)
Regulation of Fluid Intake
Hypothalamus
Regulation of Output
•Controlled by urine volume
•Support existing fluid levels and slow rate of loss
•Na+ reabsorption and ADH
•Osmoreceptors – group of neurons in hypothalamus, respond to osmolarity
Urinary System
2 kidneys
2 ureters
Urinary bladder
Urethra
Kidney Functions
Primary role in excretion, other functions:
• Filters blood plasma
• Regulates
– osmolarity of body fluids, blood volume, BP
– acid base balance
• Secretes
– erythropoietin and renin
– calcitriol
• Gluconeogenesis
Nitrogenous Wastes
• Urea– proteinsamino acids NH2 removed
forms ammonia, liver converts to urea
• Uric acid– nucleic acid catabolism
• Creatinine– creatine phosphate catabolism
Thermometer
Shunt
ArteryVein
Bloodpump
Bubbletrap
Cutaway viewof dialysischamber
Flowmeter
Todrain
Dialysisfluid
Dialysistubing
Renal Failure
• Blood urea nitrogen (BUN)– 10-20 mg/dL– azotemia: BUN, nitrogenous wastes in blood
– uremia: toxic effects as wastes accumulate
• Renal insufficiency– Hemodialysis:
Excretion
• Separation of wastes from body fluids and eliminating them.
– respiratory
– integumentary: water, salts, lactic acid, urea
– digestive: water, salts, CO2, lipids, bile pigments, cholesterol
– urinary: many metabolic wastes, toxins, drugs, hormones, salts, H+ and water
Anatomy of Kidney
• CT coverings– renal fascia– perirenal fat capsule (adipose capsule)– fibrous (renal) capsule
Anatomy of Kidney
• Renal Parenchyma:
– Renal cortex: outer 1 cm
– Renal medulla: renal columns, pyramids - papilla
• Renal sinus
– Minor calyx
– Major calyx
– Renal pelvis ureter
Renal vein
Arcuate vein
Interlobar veins
Renal artery
Cortical radiate veins
Segmental artery
Interlobar artery
Arcuate artery Cortical radiate arteries
Afferent arterioles
Glomerulus toefferent arterioles
to capillaries ofthe nephron
Renal Circulation
Efferent arteriole
Glomerulus inrenal corpuscle
Afferent arteriole
Peritubular capillaries
To the corticalradiate vein
A cortical nephron
Renal Circulation
Efferent arteriole
Capillaries ofthe vasa recta
Afferent arteriole
Peritubular capillaries
To corticalradiate vein
A juxtamedullary nephron
NephronRenal Corpuscle
• Glomerulus and Bowman’s capsule (glomerular)• Glomerular filtrate collects in capsular space flows into renal
tubule
NephronRenal Tubule
• Proximal convoluted tubule (PCT)– simple cuboidal with brush border
• Nephron loop - descending and ascending limbs– thick segment (simple cuboidal)– thin segment (simple squamous)– Creates osmotic gradient thru counter-current multiplication
• Distal convoluted tubule (DCT)– Cuboidal epithelium; end of nephron
• Collecting duct– simple cuboidal– Papillary duct
Renal medulla
The thin descendinglimb is permeable to water, but impermeableto solutes, includingurea.
KEY
Urea
Renal cortex
ClNa
The thick ascendinglimb of the nephronloop is impermeable to water and solutes.
The DCT andthe collectingducts areimpermeableto urea buthave variablepermeabilityto water.
Waterreabsorption
Variable waterreabsorption
NephronRenal Tubule
Flow of Filtrate
– Bowman’s capsule PCT nephron loop DCT collecting duct papillary duct minor calyx major calyx renal pelvis ureter urinary bladder urethra
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Renal capsule
Collecting ductNephron
(a)
(c)
Cortical nephron
CortexMedulla
GlomerulusGlomerular capsule
Renal corpuscle:
Nephron loop:Descending limbAscending limb
Thick segmentThin segment
Flow of tubular fluidFlow of blood
Key
(b)
Renalcortex
Renalmedulla
Renalpapilla
Minorcalyx
Efferentarteriole
Afferentarteriole
Proximalconvolutedtubule (PCT)
Distalconvolutedtubule (DCT)
Collectingduct (CD)
Papillaryduct
Collectingduct
Nephronloops
Juxtamedullarynephron
Convoluted tubules(PCT and DCT)