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Describe the formation of the metanephros (week 5)
- 1) Ureteric bud dev. from the caudal-post portion of the mesonephric duct
- 2) This grows towards the metanephric mesoderm
- 3) M. mesoderm induces bud to undergo extensive branching
- 4) U. bud forms: ureter, renal pelvis, calyces, collecting tubules
- 5) Coll. tubules induce mesoderm to diff into nephrons (Bowman's, PCT, LOH, DCT)
- 6) DCT connects to collecting tubule
What are the bladder and the urethra formed from?
from the cloaca (blind-ending sac of the gut tube)
Describe renal agenesis
failed formation of U. bud. Results in oligohydroamnios because kidney isn't working (deformities, lung hypoplasia)
What is the duplication of the Ureter?
ureteric bud splits early (2 ureters drain a single kidney). Causes reflux and infection.
Describe Horseshoe kindey
Kidneys fail to fully part and get trapped under the IMA. Usually asymptomatic, although they are more susceptible to damage.
Describe accessory renal arteries
failed regression of low level arteries as the kidneys ascend to their final position. Mostly a surgical risk.
What is tonicity, how is it related to the osmolality
tonicity is related to the effect of a solution on the cellular volume. Only the same as osmolality if the solute CANNOT pass through the cell membrane.
Approximate the body fluid distribution by percentage of total body weight
- 20, 40, 60 rule
- 20% extracellular: interstitial fluid (16%), plasma (4%), transcellular (1-3%)
- 40% intracellular
- 60% of your body mass is fluid
What are the major solutes in the ECF and ICF
- ECF: Na+, HCO3-, Cl-
- ICF: K+, phosphates, proteins
What are the 9 functions of the kidneys?
- 1) maintain H2O balance
- 2) regulate concentration of most extracellular ions
- 3) maintain BP and BV (RAAS, salt concentrations)
- 4) maintain proper acid-base balance
- 5) maintain osmolarity
- 6) excrete metabolites (urea, uric acid, creatinine, hemoglobin breakdown products)
- 7) excrete foreign compounds
- 8) secrete erythropoietin (stimulates RBC production in response to renal hypoxia)
- 9) convert vit D to its active form (enhanve Ca++ reabsorption)
What are the two types of nephrons? What is the difference?
Cortical nephron: BV's look more like spaghetti, 85-90% of nephrons, barely pierces the medulla
Juxtamedullary nephron: 15-20% of nephrons, long LOH extending deep into the medulla, vasa recta (vascular supply distal to efferent arteriole), good at making concentrated urine
What are the 5 parts of the vascular system relevant to urine formation
- 1) afferent arteriole
- 2) glomerulus
- 3) efferent arteriole
- 4) second capillary network
- 5) venules
What forms the filtration membrane of the kidney
- 1) capillary endothelium (fenestrae are about 70 nm)
- 2) BM of visceral layer shared with capillary BM (most filtration here, glycoproteins discourage protein movement across membrane)
- 3) podocyte filtration slits (4-14 nm)
What makes up the cortex?
- Renal corpuscles
- Cortical labyrinth (PCT and DCT)
- Medullary rays
What are the components of the nephron?
- 1) renal corpuscle
- 2) PCT
- 3) LOH
- 4) DCT
- 5) Collecting tubules and ducts (not strictly saying though)
What are the functions of the fused basal lamina?
- filtration: (main barrier, charge barrier)
- support of endothelial cells
- resist stretching in high BPs
What types are cells are present in the
a) connecting tubule
b) collecting tubule
a) connecting tubule cells (K+ reabs.); intercalated cells (H+ and HCO3- secretion)
b) Intercalated cells (same as above), principal cells (resorb. Na+)
Describe how K+ secretion is controlled in the collecting duct
- 1) increase in tubular flow bends cilia in principal cells
- 2) activates PKD channel complex
- 3) increases Ca++ intracellular concentration
- 4) Ca++ opens K+ channels at the apical membrane
- 5) increases K+ secretion
Where does ADH work?
Collecting tubule and collecting duct
What are the 4 muscles of the posterior abdominal wall
Psoas Major (thigh flexion, lateral spine flexion), Psoas Minor, Iliacus (flexes thigh), Quadratus lumborum (extend vertebrae)
Name the 8 nerves of the posterior wall and their roots
- Subcostal (T1)
- Obturator (L2-L4)
- Femoral (L2-L4)
- Lumbosacral Trunk (L4, L5)
- Ilioninguinal (L1)
- Iliohypogastric (L1)
- Genitofemoral (L1,L2)
- Lateral Cutaneous nerve to the thigh (L2-L3)
Describe the tributaries of the IVC
- -formed by union of Rt and Lt common iliac (L5)
- -two large pairs: hepatic vv and renal vv
- -two single: Rt. suprarenal, Rt. gonadal (left ones drain into lt renal v)
Describe the 4 layers that surround the kidneys
- -renal capsule (important in cancer prognosis)
- -perirenal fat (surrounds kidney and adrenal gland)
- -renal fascia (connects to the diaphragm)
- -pararenal fat (outermost layer)
What are the anterior and posterior relationships of the rt and lt kidneys
- -Rt anterior: right colic flexure, liver, SI
- -lt anterior: left colic flexure, stomach, spleen, SI
- -both posterior: muscles (psoas major, quad. lumborum, transverse abdominal), nerves (subcostal, iliohypogastric, ilioinguinal), diaphragms, 11th and 12th ribs (lt), 11th rib (rt)
Describe the innervation and lymphatic drainage
innervation: para (vagus), symp (thoracic splanchnic nn)
lymph: aortic (lumbar) LNs
List the relationships of the ureter
- -retroperitoneal (closely adhere to peritoneum)
- -anterior to psoas major
- -close to the IVC on the right
- -anterior to the aortic bifurcation
Where are the three ureter constrictions?
- 1) when they join the renal pelvis
- 2) when crossing the pelvic brim
- 3) when they enter the bladder
Describe the venous drainage of the suprarenal glands
- right: all three veins drain to IVC
- left: all three veins drain to left renal vein
What are the three main factors that regulate GFR?
- Capillary surface area
- Membrane permeanbility
What are the three basic mechanisms to control GCP?
- 1) autoregulation (i.e. independent of neural or hormonal control)
- 2) extrinsic symp. control
- 3) hormonal regulation
Describe tubulogolerular feedback
- 1) NaCl flow is detected via the macula densa cells
- 2) increase NaCl flow is causes constriction of afferent arteriole and vice versa
- -more specifically, increased Cl taken up in the macula densa cells causes them to take up Ca++ and thus release ATP and adenosine which causes a Ca++ influx in the SM cells in the afferent arteriole
- works with myogenic mechanism to control afferent arteriole diameter
Describe what activates the RAAS and how it works
- 1) decrease in Na+ (or symp. stimulation) causes the juxtaglomerular (granular) cells to release renin in afferent art.
- 2) renin converts ANGogen to ANGI
- 3) ACE converts ANGI to ANGII
- 4) ANGII stimulates aldosterone release from adrenal glands and systemically vasoconstricts
- 5) aldosterone upregulates sodium channels in distal tubule and CD, increasing Na and (thus) H2O reabsorption
- 6) ANG II also increases Na reabsorption at the PCT
How does ANP work?
- -released in response to stretching of atria
- -inhibits Na and thus H2O reabsorption
- -inhibits ADH and aldosterone release
- -causes relaxation of mesangial cells (in glomerulus) thereby increasing the surface area (thus increasing GFR)
What does ANG II do?
- -constricts afferent arteriole
- -causes release of aldosterone (Na and H2O uptake increased)
- -increases thirst
- -causes release of ADH
Describe glucose absorption
- -almost all in proximal tubule
- -2 transporters
- -SGLT's: cotrans with Na, apical mem
- -GLUT: basolateral mem.
Name the layers of the excretory system
- -adventitia or serosa
What are the three parts of the male urethra?
- Prostatic: transitional epithel
- membranous: stratified columnar
- penile: columnar and strat. squam. (distally)
What is the purpose of tubular secretion?
decrease concentration of metabolic by-products and toxic substances in plasma
Describe how urea recycling works
What are 6 criteria for a substance to me a good measure of renal clearance.
- 1) filter freely into bowman's
- 2) not be reabsorbed
- 3) not be secreted by tubular system
- 4) not metabolized by kidneys
- 5) no be produced in kidneys
- 6) not alter GFR
Name 3 different compensating mechanisms for acid-base balance
- 1) acid-base buffer systems: almost immediate compensation, usually weak acids (e.g. proteins, phosphate (ICF and DT and CD), bicarbonate (ECF))
- 2) respiratory regulation: takes minutes, imprecise
- 3) renal regulation: takes hours to days, greater capacity to correct than (2), reabsorb HCO3- and secrete H+, phosphate, ammonia, bicarbonate systems
What does endothelin-1 and cortisol do?
endothelin-1: enhance H+-Na+ antiporter on apical membrane and, Na+-HCO3- symporter on basolateral membrane
cortisol (adrenal cortex): upregulates these same transporters
Describe the compensation for metabolic and respiratory acidosis and alkalosis
- RAc) kidneys secrete more H+ and make more HCO3-
- MAc) increase ventilation
- RAlk) decrease H+ secretion and make less HCO3-
- MAlk) decrease ventilation