Renal Q1 Flashcards
What is the term for Uremic Toxicity due to increased plasma creatinine and BUN (urea)
Azotemia
Give an example of 2 endogenous waste products excreted by the kidney
UREA (aka BUN - Blood Urea Nitrogen)
Creatinine
An increase in Angiotensin II will do what?
Increase Vasoconstriction
An increase in aldosterone will do what?
Decrease urinary Na+ excretion
What form of Vitamin D does the Kidney produce?
1,25 (OH)2 Vitamin D
What are 2 consequences of Impaired Renal Function that go hand in hand?
Low pH (metabolic acidosis)
High Potassium (Hyperkalemia)
What 2 places is Erythropoietin synthesized?
By what transcription factor?
Peritubular fibroblasts and Endothelial cells
HIF-1
Where does 25 Vita D convert into 1,25 Vita D in the kidney?
What enzyme is involved?
Proximal tubule cells
via 1 alpha-Hydroxylase
T/F
The kidney is involved in gluconeogenesis
True
What pH is considered Metabolic Acidosis?
What Potassium level is considered Hyperkalemic?
pH 4.0 mEq/L
What does a decrease in 1,25 VitaD cause?
Calcium Phosphate imbalance and Bone Fractures
What does Plasma Protein Imbalance cause?
Edema
excess interstitial fluid
T/F
Impaired renal function can decrease the immune system
True
T/F
Impaired renal function can cause Anemia
True
Decreases Erythropoietin synthesis
What is Renal functional reserve capacity?
What is the lower limit of fluid homeostatic maintenance?
At what point does the patient need dialysis?
Kidney can maintain GFR (glomerular filtration rate) at reduced function
20%
10-15%
What percentage of adults have some form of kidney disease?
10%`
Name 3 causes of Acute Renal Failure (ARF)
Pre-renal (decrease renal blood flow)
Intra-renal (e.g. acute tubular necrosis)
Post-renal (obstruction)
T/F
ARF is usually reversible
True
T/F
CRF is usually reversible
False
Name 3 causes of Chronic Renal Failure (CRF)
Diabetes
Hypertension
Glomerulonephritis
What are the 2 treatment options for End Stage Renal Disease?
Dialysis
Transplant
How does Hemodialysis differ from Peritoneal dialysis?
Hemodialysis: Blood pumped into machine across membrane
Peritoneal dialysis: fluid exchanged through peritoneum
In Hemodialysis, what 3 things usually diffuse out of blood?
What diffuses in?
Water, Creatinine, Potassium
Bicarb
How often is Hemodialysis administered?
What drug must be taken?
3-4 times/week
3-4 hours each session
Blood thinners
How often is fluid exchanged in CAPD (chronic ambulatory peritoneal dialysis)?
What is a major risk?
4-6 times/day
Infection
Is body fluid homeostasis maintained with hemodialysis?
No
What occurs between hemodialysis sessions?
2 limitations
Body weight increases
(water retention)
Plasma creatinine increases
(synth > output)
1 millimolar solution of CaCl2 = _____ mEq Ca+2 and _____ mEq Cl-
2
2
What 2 factors affect the percentage or TBW (total body water)?
Gender
Age
What percentage of TBW is intracellular and extracellular?
Intracellular - 2/3
Extracellular - 1/3
What are the 3 components of the ECF (extracellular fluid) and what is their breakdown?
Interstitial fluid - 75%
Plasma - 25%
Transcellular fluid - 5%
What makes up transcellular fluid?
CSF
Aqueous humor
GI tract secretions
Urine
What separates body fluid compartments?
Vascular Endothelium
Intracellular fluid is high in what cation?
Extracellular fluid is high in what cation?
What sets up this dynamic?
Intra - potassium
Extra - sodium
sodium potassium pump
What 3 things is ICF high in?
What 3 things is ECF high in?
ICF - K+, proteins, organic phosphates
ECF - Na+, Cl-, bicarb
What are 2 factors that help set up solute differential between ECF and ICF?
ATP-ase Na/K pump
Membrane transporters
Why is ECF volume directly related to total NaCl content?
Na+ and attendant ions (Cl-/HCO3-) account for 95% ECF osmolarity
What is the dilution principle equation?
Volume = Amount added / Concentration
What are the 4 markers used to measure Extracellular Volume?
Radiolabeled sodium
Sucrose
Mannitol
Inulin
What are 2 markers used to measure Plasma Volume?
Iodinated Albumin
T-1824 (Evans blue)
What are 3 markers used to measure Total Body Water?
Tritiated water
Heavy water
Antipyrine
How does one measure Interstitial Volume?
Extracellular fluid volume - Plasma volume
How does one measure Intracellular Volume?
Total body water - Extracellular Fluid volume
Why is it not possible to measure Interstitial or Intracellular volume directly?
There is no clinical method for taking a direct interstitial or intracellular fluid sample from a living patient
Why is it important to use a single marker if multiple measurements of a specific compartment volume are required?
Markers that are used in the same space may give slightly varying values based on composition differences of the marker
What happens to RBC in hypotonic solution?
Expansion
What happens to RBC in hypertonic solution?
Shrinkage
Why is urea often Hypotonic?
Cell membrane is permeable to urea
Reflection coefficient is not zero
(quantitatively might appear isotonic, but remember this is referring to water - if permeable to urea will often be Hypo)
Name 4 ways the intracellular-extracellular fluid volume can be disrupted.
Water ingestion
dehydration
infusions
fluid loss
Fluid exchange between the interstitium and the intracellular space is driven primarily by…
Osmotic Pressure
*water movement only
What are the 2 major renal zones?
Outer Cortex
Inner Medulla
What is the relationship between the renal tissue and the renal calyces and pelvis?
Distal proximal tubules of nephrons transfer filtrate to medullary collecting ducts that converge at inner edge of medulla forming calyces
What are the 4 principal segments of the Nephron?
Proximal tubule
Loop of Henle
Distal tubule
Collecting tubule
What are the 2 types of nephrons?
Where are the glomeruli located?
Cortical (short looped)
glomerulus close to surface
Juxtamedullary (long looped)
glomerulus at cortex/medulla junction
In the Cortical (short looped) nephron, where are the following located:
Proximal and distal tubule
Loop of Henle
Collecting tubule
Cortex
Cortex and Outer Medulla
Cortex, Outer medulla, Inner medulla
In the Juxtamedullary nephron, where are the following located:
Proximal and distal tubule
Loop of Henle
Collecting tubule
Cortex
Cortex, Outer and Inner Medulla
Cortex, Outer and Inner Medulla
What is the anatomical difference between the Cortical and Juxtamedullary Nephrons?
Juxtamedullary has
Loop of Henle in Inner Medulla
*cortical nephrons only go as far as outer medulla
What are the proportions of Cortical and Juxtamedullary Nephrons?
Cortical - 80%
Juxtamedullary - 20%
Juxtamedullary Nephrons appear to have a cross species function of what?
Concentrating Urine
In what way is the vascular arrangement surrounding the glomerulus unique?
What is the pathway?
(4 things)
2 sets of Arterioles
afferent arteriole > glomerular capillaries > efferent arteriole > peritubular capillaries
What do 2 sets of Arterioles do in the glomerulus?
Help regulate Glomerular Filtration
*upstream and downstream regulation of glomerular capillaries
What is the function of peritubular capillaries?
Reabsorption
- travel alongside length of nephron
- *Vasa Recta in Loop of Henle
What is the Vasa Recta?
Subset of Peritubular capillaries running alongside Loop of Henle
From what are the Vasa Recta derived?
Efferent arterioles of Juxtamedullary Nephrons
What percentage of cardiac output is delivered to the kidney?
25%
How does Renal Oxygen consumption compare with other organs?
Very high
Why is artery-vein Oxygen concentration analysis in the kidney deceptive when ascertaining consumption?
Oxygen concentration difference low
BUT,
Blood flow is so high, Kidney Oxygen consumption also very high
How is Renal Oxygen consumption calculated?
equation
Oxygen consumption = a-v Oxygen difference x Blood Flow
Describe Phase 1 of Renal Blood flow and Oxygen consumption
Above 150, proportional
*no change in a-v Oxygen difference
Describe Phase 2 of Renal blood flow to Oxygen consumption
150-75, kidney works harder to extract oxygen
*a-v Oxygen difference increases
Describe Phase 3 of Renal blood flow to Oxygen consumption
Below 75, a-v difference maximal
*Renal Ischemia
What are the 3 principal elements of Renal Function?
Glomerular Filtration
Tubular Reabsorption
Tubular Secretion
What is the Filtration Fraction?
20%
*plasma entering glomerular capillaries filtered into Bowman’s Space
What is the Filtered Load?
Concentration of Solutes in glomerular capillary
How does Tubular Secretion maintain homeostasis?
What is it making up for?
Glomerulus doesn’t filter large, charged molecules.
glomerulus selective
Are conclusions drawn from urine concentration alone?
What must you know?
No.
Must know Urine Flow Rate
How does Urine move to the Bladder?
Calices initiate Peristaltic Contraction via inherent pacemaker activity
What is the Micturition Reflex?
What contracts and relaxes?
Parasympathetic response as bladder fills
Detrusor contracts
Bladder neck relaxes
What is the Voluntary component of the Micturition Reflex?
External Urethral Sphincter
*internal by bladder is involuntary
Name 2 Micturition abnormalities
Automatic bladder
(spinal cord damage of voluntary supression)
Atonic bladder (loss of sensory nerves = no reflex, leads to overflow incontinence)
What are the principal structural components of the Glomerular filtration barrier?
(3 things)
Fenestrated Endothelium
Basement membrane
Epithelium (podocytes)
5 functions of Mesangial cells:
Structural support for capillaries Secrete ECM Phagocytosis Secrete Prostaglandins/cytokines Contractile
What 2 main factors determine filterability?
Size
Charge
T/F
For “freely filtered” substances, the concentration of solutes in Bowman’s space will be = plasma.
True
What results in high protein plasma concentration immediately downstream of the Glomerulus?
Proteins aren’t filtered across glomerulus
T/F
Bowman’s glomerulus has no Oncotic Pressure
True
T/F
Oncotic Pressure increases from Afferent to Efferent arteriole.
True
What is often seen in Glomerular Disease?
Proteinuria
Name 4 consequences to Proteinuria do to Glomerular Disease.
Thrombosis
Infection
Hyperlipidemia
Edema
What are the main forces in the Glomerular capillary?
2 types?
Starling Forces
Hydrostatic and Oncotic
What is the difference between osmotic and oncotic pressure?
Oncotic due to Protein
What is the term for the Filtration coefficient?
How is it determined?
Kf
ability of capillaries to allow passage of water
T/F Glomerular filtration (Kf) is much higher than in systemic capillaries
True
What causes Generalized Edema?
Na+ retention
*expands entire ECF volume
What are 3 causes of Localized Edema?
Venous obstruction (increase Pc) Inflammation (increase Pc and Kf) Lymphatic obstruction (increases Pi-c)
*protein not returned to systemic circulation in lymphatic obstruction
Why does Glomerular capillary Hydrostatic pressure remain relatively constant?
Afferent and Efferent resistance points at arterioles
Why does oncotic pressure increase along the glomerular capillary?
Protein not filtered into glomerulus
When does the Net Filtration Pressure = 0?
When Oncotic Pressure in the glomerular capillary increases to the point it = Hydrostatic Pressure
Filtration Pressure Equilibrium and Disequilibrium?
???
Why is Hydrostatic pressure so low by the time the blood reaches the Peritubular capillaries?
It has passed 2 resistance points
*before and after Bowman’s Capsule
What is the Ultrafiltration coefficient?
Filtration coefficient of a semipermeable membrane
How does the Glomerular Ultrafiltration coefficient compare to systemic Ultrafiltration?
Much higher in Glomerulus
How many times/day is the entire plasma volume filtered by the kidneys?
60
T/F
Everything increases/decreases with Afferent arteriole increase/decrease in pressure
True
*Hydrostatic Pressure, Glomerular Filtration Rate, and Renal Plasma Flow
T/F
Hydrostatic Pressure, Glomerular Filtration, and Renal Plasma flow all increase/decrease with increase/decrease of Efferent arteriole pressure.
False
*Inverse on Renal Plasma Flow
What primarily regulates Glomerular Filtration?
Afferent Arteriole
What two factors constrict the Afferent Arteriole?
Sympathetic nerves
Angiotensin II
affects both afferent and efferent
What do Prostaglandins do to regulate glomerular filtration?
What are 2 examples of such prostaglandins?
Vasodilate
PGE2 and PGI2
T/F
Angiotensin II, along with constricting the glomerular arterioles, also causes production of PGE2 and PGI2, which constricts said arterioles.
True
What can NSAID’s + Sympathetic nerve activity lead to?
Acute Renal failure
- no vasodilation occurring
- *runaway vasoconstriction of kidney
What does an increase in Afferent vasoconstriction due to Renal Sympathetic Activity and Angiotensin II cause?
“Pre-renal” acute renal failure
What are 3 main factors that adversely affect the GFR?
Kf (ultrafiltration coefficient) change
(glomerular disease or mesangial cell contractility)
Oncotic pressure change
Intratubular pressure change (obstruction)
What does Mesangial cell contractility affect?
Capillary surface area
How does complete Uretal obstruction stop GFR completely?
Damages glomeruli through pressure build-up
What is the Uretorenal reflex?
Sympathetic reflex constricting arterioles due to Uretal Obstruction
Why doesn’t the GFR constantly change with normal fluctuations of pressure?
Autoregulatory nature of kidney
- maintains GFR over wide range of pressures
- *70 and above
Why do we know Autoregulation of kidney is intrinsic?
Transplanted kidneys
Perfused isolated kidneys (in vitro, no hormones)
T/F
Resistance changes in the Afferent Arteriole cause changes in the Glomerular Filtration Rate and the Renal Perfusion Rate
True
*this is why we know Afferent Arteriole is control point
T/F
Autoregulation prevents changes in GFR and RPF and prevents large changes in water and solute excretion
True
Reflex resistance changes in the Afferent Arteriole is the _______ theory of Autoregulation.
Myogenic
T/F
Under the Myogenic theory, an increase in BP would decrease the radius of the Afferent arteriole.
True
A change in the flow rate/composition of tubular fluid sensed at the Macula Densa is the _____ theory of Autoregulation
Tubuloglomerular feedback theory
An increase in BP causing an increase of flow rate causes the Macula densa to decrease Afferent Arteriole diameter according to the tubuloglomerular feedback theory of autoregulation.
True
What is the Macula Densa?
Specialized cells at border of Distal Convoluted Tubule
*close proximity to the Afferent arteriole
What can override the Autoregulatory system in the Kidney?
Under what circumstances is this a good thing?
Sympathetic system
Trauma
don’t want vasodilation to occur with massive blood loss
