GU Block 1 Flashcards
Where are kidneys and ureters located withing the body?
What are the 3 external layers covering the kidney?
Retroperitoneal, T11-L3
Fascia Adipose Capsules
What are the 3 internal layers of the kidneys
What is the functional organ, tissue and unit of the GU/kidney?
Cortex Medulla Pelvis
Kidney, Parenchyma, Nephron
Where do vessels and nerve structures enter/leave the kidney?
What is the path of blood to and from the kidney
Hilum
Abdominal aorta Renal artery Afferent arterioles Glomerulus Efferent arterioles Peritubular capillaries Vasa recta Renal vein IVC
What part of the NS regulates filtration and urine formation?
What other process is innervated here?
Sympathetic: superior mesenteric, innervates arterioles
RAAS- dec BP
Renin secretion- inc BP
What does a nephron consist of?
Where do ACEIs/ARBS exert their effects?
Renal corpuscle (glomerulus, Bowmans) Renal tubules (PCT, LoH, DCT)
Afferent arteriole
What are the 8 major functions of the kidneys?
Regulate blood ions, pH, volume BP regulation Maintain blood osmolarity Produce hormones Regulate blood glucose Excrete wastes
Kidneys regulate blood levels of what 5 E+
Where is renin secreted from and leads to ? result?
Na K Ca Cl PO4
Juxtaglomerular cells
Inc BP
Kidneys maintain blood osmolarity at ?
What are the two hormones produced in the kidneys?
300/L
Calcitriol- active form of Vit D, regulates PO4/Ca
EPO- stim production of RBCs in marrow
Production of urine is the end result of what 3 processes?
Define Glomerular Filtrate
Glomerular filtration
Tubular reabsorption
Tubular secretion
Fluid entering capsular space
What are the 3 components of glomerular filtration membrane?
Fenestrations- allows proteins/excludes cells/platelets
Basal lamina- allows small/med proteins through
Slit membrane- located between pedicels, only allows very small proteins through
Define Filtration Fraction
How much blood flows through kidneys?
How much GFR flows through kidneys each day?
Ratio of fluid from blood that becomes glomerular filtrate- 20% of total fluid reaching kidney becomes capsular space
1-1.2L/min
140-180L/day
What is a normal net filtration pressure w/in kidneys?
What are the 3 pressures and the changes occurring during glomerular filtration
10mmHg
Glomerular hydrostatic- 55mmHg
Capsular hydrostatic- 15mmHg
Blood colloid- 30mmHG
Water makes up 95% of urine, how much Na and K is found normally?
What is the fluid capacity of the bladder?
Na- 1g/L
K- 0.75g/L
700-800mL
What are the 3 layers of the bladder?
Mucosa- transitional epitherlium
Muscularis- detrusor
Serosa- superior surface covering or,
Adventitia- covers post/inf surface and continuous w/ ureters
2/3 of body water is ? and remaining 1/3 is ?
Of the 1/3 part, how much is intravascular?
2/3: intracellular
1/3: extracellular
1/4
Define Osmolality
Define Osmolarity
Solution concentration expressed as total solute particles/kg
Solution concentration expressed as total milimoles/L
Fat’s water content is ? than muscle
This is why obese people’s ratio is ?
Lower than muscle
Lower ratio of total body water to body weight
Define Tonicity
A solution’s tonicity is related to its ?
Ability of extracellular solution to make water move in/out of cell via osmosis
Osmolarity, total concentration of all solutes in a solution
Define Hypotonic
Define Isotonic
Define Hypertonic
ECF w/ lower osmolarity than the ICF, net flow is into cell
Same osmolarity between ICF/ECF w/ no water movement
ECF w/ higher osmolarity than inside the cell, water moves out of cell
What is the gold standard for evaluating renal E+ excretion?
What is a better method?
24hr urine collection
Fractional excretion of an E+ from spot urine samples
What does a Low FEx indicate?
What does a High FEx indicate?
Renal absorption, high avidity/E+ retention
Renal wasting, low avidity/E+ excretion
What does an FEx below 1% mean?
What does an FEx above 2% mean?
Pre-renal Dz (low output HF)
Acute tubular necrosis
What is the natural physiologic response to a decrease in renal perfusion?
Why is the natural response of sodium wasting seen w/ high FEx
Inc Na reabsorption
Tubular necrosis causes loss of Na/hypervolemia
Physiologic solute concentration is normally between ?
Define Tonicity
285-295mmol/kg
Osmolytes that are impermeable to cell membranes
Define Ineffective Osmoles
What is the major extracellular cation
Substances that easily permeate cell membranes and don’t contribute to tonicity and don’t cause shifts across compartments
Na
Define Osmolal gap
What does the presence of this gap suggest?
Discrepancy between measured and estimated osmolality more than 10mmol/kg
Presence of unmeasured osmoles- ethanol, methanol, ethylene glycol, mannitol, propylene glycol and isopropanol
Normally, how many mosmols need to be excreted each day?
What is the max urine osmolality?
What is the minimum urine output required for neural solute balance
60
1200mosmol/kg
500mL/day
Obligatory renal water loss is mandated by ?
How is serum sodium calculated
Minimum solute excretion required to maintain a steady state
Exchangeable Na + Exchangeable K/ Total body water
What is the primary stimulus for water ingestion?
What mediates this stimulus
Thirst
Inc effective osmolality
Dec ECF volume
Osmoreceptors are stimulated by ?
What is the average osmotic threshold for thirst?
Rise in tonicity
295 mosmol/kg
What is the major stimulus for ADH release
Osmolality is primarily determined by ?
Hypertonicity
Na concentrations
What are the 3 steps required for maintaining homeostasis and normal plasma Na
Filtration, delivery of water/E+ to diluting site of nephron
Active reabsoprtion of Na/Cl w/out water in ascending LoH
Maintenance of dilute urine due to CD impermeability if no ADH is present
Hypotonic fluids often contribute to hospitalized PTs acquiring ?
Hyponatremia start at ? level and reflects ?
Hyponatremia- MC E+ abnormality in hospitalized PTs from too much IV fluid
<135mEq
Excess water relative to Na levels
Define Isotonic Hyponatermia
What two conditions can this occur in?
Pseudohyponatremia- lab error underestimating Na concentrations
Hyperlipidemia
Hyperproteinemia
Pseudohyponatremia does not occur if serum Na is measured by ?
Hypertonic Hyponatremia is AKA and defined as ?
What type of result does this cause?
Ion specific electrode in direct assay of undiluted serum specimen
Translocational Hyponatremia- large amounts of substance can’t cross membrane, added to ECF compartment
Pulls intracellular water into ECF, dilutes sodium
What are two examples of Hypertonic hyponatremia etiologies
What type of d/o is this?
Hyperglycemia
Iatrogenic mannitol administration
Water redistributing in response to change of tonicity
Most causes of hyponatremia are ?
What are the 3 categories
Hypotonic
Hypovolemic Hypo Hypo
Euvolemic Hypo Hypo- STREP
Hypervolemic Hypo Hypo
Hypovolemic Hypotonic Hyponatremia
Occurs d/t extra/renal volume loss w/ hypotonic replacement
Total Na and water dec
ADH release= retained water
Osmolality sacrificed to preserve intravascular volume
What urine Na results indicate if volume loss is renal or extrarenal?
SIADH
Renal: >20 mEq
Extra: <10 mEq
Hypo Hypo Hypo
ADH released d/t hyperosmolality/dec arterial volume
Inappropriate water retained= concentrated urine (+300mEq) w/ high Na (>20mEq)
What are 3 common causes of Hypo Hypo Hypo-SIADH
Hypo Hypo Hypo- Hormonal abnormalities
CNS Pulm d/o and Malignancy
Severe hypothyroid and glucocorticoid insufficiency; can NOT be differentiated from SIADH w/ urine/serum results
Hypo Hypo Hypo Psychogenic Polydipsia and Low Solute diet
Hypo Hypo Hypo- Reset Osmostat
PT ingests normal solute diet but also 10-15L of water; kidney retain water, can’t excrete pure water
Appropriate ADH response to water deprivation/fluid challenges (pregnancy)
Hypo Hypo Hypo Exercise associated
Why are sports drinks not actually that good?
Combo of excessive hypotonic intake w/ inappropriate ADH secretion (basic trainee forced hydration)
Hypotonic compared to serum
Hypervolemic Hypotonic Hyponatremia
Cirrhosis, HF, Nephrotic syndrome, Adv KDz
Cirr/HF- dec volume from dilation/dec output causes ADH secretion
Dec osmolality in attempt to restore arterial volume
What are the Sxs of hyponatremia
What causes more severe Sxs
What labs would be considered?
Mainly neuro/brain edema
Mild 130-135: gait fall Fx
Sev <120: seizure herniation coma death
Sudden/rapid E+ shifts
Serum: E+ Cr Osmolality
Urine: Na K Osmolality
Thyroid/Adrenal function
What will be seen on lab results to Dx SIADH
What will be seen on lab results in Pseudohypnatremia and how is it Tx
Normal thyroid/adrenal function Urine Na >20mEq Dec BUN <5-10mg Hypouricemia <4mg ADH levels not required
HyperTG, Hyperproteinemia
No Tx req’d
How is Translocational Hyponatremia Tx
How fast does chronic hypotonic hyponatremia need to be corrected?
What can happen if Tx is too fast?
Tx hyperglycemia, d/c Mannitol
4-6mEq/L/24hrs
No more than 6-8/24
Osmotic demyelination syndrome (central pontine myelitis)
If hyponatremia is Tx too quickly, what S/Sxs will be seen?
What is the adverse outcome of Tx Translocational HypoNa too quickly?
Flaccid paralysis Dysarthria
Dysphagia
Rapid reduction of osmolality= cerebral edema