Valley: Renal Functions Flashcards
—— are 90% of total osmolality of the extracellular fluid
Sodium salts
When we talk about regulating osmolality, we are talking about regulating — concentration
sodium
Normal osmolality is about — mOsm/l
300 ; 270-310
Conservation of non-ionic components of plasma: (5)
Glucose, amino acids, proteins, water, vitamins
Excretion of non-volatile end-products of metabolism: (6)
HP042-, Urea, Uric Acid, S042-, Creatinine, Lactic Acid
Maintenance of extracellular fluid volume is achieved by controlling — and — excretion
salt (NaCI) and water
3 Endocrine functions:
Erythropoietin, renin-angiotensin system, vitamin D
Renal hormone that acts on bone marrow and stimulates red blood cell production
Erythropoietin
the patient with chronic renal disease is anemic because there is a deficiency of —.
erythropoietin
Enzyme-hormone system that participates in blood pressure regulation, potassium excretion,
and sodium excretion
Renin-angiotensin system
The kidney converts — to its physiologically active form (Vitamin D3)
vitamin D
The patient with chronic renal disease becomes — because calcium absorption from the intestine is impaired when there is a deficiency of
vitamin D.
hypocalcemic
About —% of the total quantity of blood pumped by the heart each minute, or —liters/min, passes
through the kidneys.
25 ; 1.25
As it turns out, the kidneys re-work the extracellular fluid about once every two —, thereby maintaining its composition and volume.
hours
dialysis machines are capable of re-working the extracellular space of anephric (kidney-free) patients once every 8-12 —.
hours
Blood is delivered to the glomerulus via the — arteriole and exits the glomerulus via the — arteriole.
Afferent ; efferent
What are the two types of nephrons?
Cortical nephrons and juxtamedullary nephrons
Cortical nephrons have — loops of Henle and glomeruli located near the —.
Short ; surface of the kidney
Juxtamedullary nephrons have — loops of Henle and glomeruli located deep in the cortex near the —.
Cortical medullary junction
Blood passes through the —, the —, the —, and the — before it drains into the venous system.
Afferent arterioles ; glomerular capillaries ; efferent arterioles ; peritubular capillaries
The — branches into a capillary network that entwines the renal tubule.
Efferent arteriole
The — arise from the efferent arteriole and engulf the renal tubule.
Peritubular capillaries
The — are the peritubular capillaries of the loops of Henle of the juxtamedullary nephrons.
Vasa recta
The vasa recta constitute a — exchange system.
Countercurrent
A substance may be transported form the tubule to the capillary
Reabsorption
A substance may be transported from the capillary to the tubule
Secretion
Hairpin-shaped capillaries of the long loops of Henle of the juxtamedullary nephrons
Vasa recta
What 3 parts of the kidney are found in the cortex?
Glomeruli, proximal tubules, and distal tubules
What 2 parts of the kidney are found in the medulla?
Loops of Henle and collecting ducts
The — of the kidney is most vulnerable to ischemia (secondary to hypotension)
Inner stripe of the outer medulla
Name most of the kidney (pic)
Movement, under pressure, of plasma water and most of its dissolved constituents from the glomerular capillary into Bowman’s capsule.
Glomerular filtration
The beat of the heart creates the high glomerular capillary — pressure that is required for the filtration process
Hydrostatic
Transport of substances out of the lumen of the renal tubule
Tubular reabsorption
Transport of substances into the lumen of the renal tubule
Tubular secretion
Reabsorbs the bulk of the filtered fluid and its dissolved constituents
Proximal tubule
Provides the coarse control mechanisms for the renal regulation of extracellular fluid volume and composition.
Proximal tubule
Establishes and maintains an osmotic gradient in the medulla of the kidney.
Loop of Henle
The — plays a critically important role in the regulation of water balance.
Osmotic gradient
The fluid leaving the loop of henle is —
Hypo-osmotic
In the loop of Henle, the handling of — and — occur independently.
NaCl and water
The loop of Henle is a — multiplier.
Countercurrent
Make final adjustments on urine pH, osmolality, and ionic composition, depending on the needs at the moment.
Distal tubule and collecting duct
The reabsorption of water is under the control of — hormone.
Antidiuretic
The reabsorption of sodium and the secretion of potassium are under the control of —.
Aldosterone
The distal tubule and collecting duct provide the fine control mechanisms for the renal regulation of — fluid composition and volume.
Extracellular
The — deposit sodium chloride in the medullary interstitium, and, in doing so, produce a gradient in osmolality that increases progressively from the corticomedullary junction to the papilla.
Loops of Henle
In humans, the osmolality in the medulla increases from — mOsm (corticomedullary junction) to — - — mOsm deep in the medulla.
300 ; 1200-1500
The — is required for making the urine concentrated or making the urine dilute.
Osmotic gradient
The cycling of — from tubules to interstitium is crucial.
Urea
Osmolality in cortex?
300
Osmolality in outer medulla?
400-600
Osmolality in inner medulla?
800-1200
The kidneys regulation of the composition of the — fluid.
Extracellular
The kidneys — of toxic substances and non-volatile end-products of metabolism.
Excretion
The kidney produces a variety of enzymes (—) and hormones (— and —) that participate in many body functions.
Renin ; erythropoietin and vitamin D
What is the functional unit of the kidney?
Nephron
One of the three basic nephron processes, is the movement of cell-free and albumin-free fluid into Bowman’s capsule from the glomerular capillaries
Glomerular filtration
Approximately — liters of blood are pumped by the heart each minute.
5
Approximately — liters (—%) of the cardiac output are delivered to the kidneys each minute.
1.25 ; 25
Approximately — liters (— milliliters) of blood plasma and its dissolved constituents (excluding
large proteins) are filtered into the renal tubules each minute.
0.125 ; 125
The bulk of the — (67%) is reabsorbed as it passes through the proximal tubule.
glomerular filtrate
The loop of Henle establishes the — in the medulla of the kidney.
osmotic gradient
The valuable constituents of the filtrate (e.g., H20, HC03 -, glucose, amino acids, Na +, K+) are reabsorbed to a large extent from the — and returned to the general circulation via the —.
proximal tubule ; peritubular capillaries
End-products of metabolism (urea, uric acid, creatinine, P042-, SOl-) are reasonably poorly — by the renal tubules.
reabsorbed
Renal — of these metabolites prevents their accumulation in the extracellular space, and cell function is thereby maintained at an optimal level.
excretion
The distal tubule and collecting duct are the nephron locations where exquisite control of — fluid composition and volume is achieved.
extracellular
Excretion of substances such as Na +, K+, and H20 are finely controlled at these sites.
The distal tubule and collecting duct
The influence of antidiuretic hormone (ADH = vasopressin) is responsible for the exquisite control of — excretion.
water
influence of aldosterone is responsible for the exquisite control of — and — excretion.
sodium and potassium
The proximal tubule has a maximum capacity for reabsorbing glucose; this maximum reabsorptive capacity for glucose is referred to as the “—” or “—’:
transfer maximum ; transport maximum
All of the filtered glucose is normally completely reabsorbed from the — by active transport mechanisms.
proximal tubule
In untreated —, the amount of glucose filtered exceeds the transfer (transport) maximum of the proximal tubule.
diabetes mellitus
All segments of the renal tubule beyond the — are impermeable to glucose.
proximal tubule
— is a disease in which in adequate amounts of insulin are produced by the pancreas.
Diabetes mellitus (sweet urine)
An increase in plasma — concentration is one of the consequences of the insulin deficiency.
glucose
When DM happens, glucose will appear in the urine because the —, —, and — are impermeable to glucose.
loop of Henle, distal tubule, and collecting duct
If glucose escapes reabsorption in the —, it is excreted.
proximal tubule
What happens to urine output in the untreated patient with diabetes mellitus? Why?
Urine flow increases because unreabsorbed glucose causes an osmotic diuresis.
The rate of — hormone release into the bloodstream is directly related to the osmolality of the extracellular fluid.
antidiuretic
An — in extracellular fluid osmolality is corrected by ingesting water and adding it to the extracellular fluid.
increase
A — in extracellular fluid osmolality is corrected by excreting water and removing it from the extracellular fluid.
decrease
Extracellular fluid osmolality (and hence sodium concentration) is regulated by — (—, —)
antidiuretic hormone (ADH, arginine vasopressin)
ADH is synthesized in the paraventricular and supraoptic nuclei of the —.
Hypothalamus
ADH is transported in the axoplasmic fluid of the hypothalamic-hypophyseal nerves to storage sites in nerve terminals of the —.
Posterior pituitary (neurohypophysis)
Nerve action potentials stimulate release of ADH from the —.
Posterior pituitary
The posterior pituitary is also known as the —.
Neurohypophysis
Which is the more potent vasoconstrictor, ADH or angiotensin II?
ADH is more potent.
In response to an increase in extracellular fluid osmolality, paraventricular and supraoptic nuclei shrink and nerve axons fire action potentials, which cause — release from the posterior pituitary
ADH
An — in extracellular fluid osmolality is the most powerful stimulus triggering the release of ADH.
increase
When ADH reaches the — and —, the reabsorption of water is increased (a small volume of concentrated urine is formed)
distal tubule and collecting duct
In response to a decrease in extracellular fluid osmolality, cells of the paraventricular and supraoptic nuclei swell and nerve action potentials are inhibited, so ADH release is —.
depressed
In the — of ADH, the distal tubule and collecting duct are impermeable to water. A large volume of dilute urine is formed.
absence
Stresses, including —, —, and — trigger the release of ADH.
hypovolemia, hypotension, and pain
Besides stressors, what other things cause an increase in ADH release?
CPAP, PEEP, volatile agents
Approximately —% of the filtered water is reabsorbed from the proximal tubule and —% from the descending limb of Henle’s loop.
67 ; 13
The ascending limb of Henle’s loop is impermeable to —.
water
Since NaCI is reabsorbed from the ascending limb, the urine becomes — (osmolality = — mOsm) when it reaches the distal tubule.
dilute ; 100
Antidiuretic hormone (ADH, arginine vasopressin) — the permeability of the distal tubule and collecting duct to H20.
increases
When circulating levels of ADH are high, a — volume (—ml/kg/hr) of concentrated urine is formed)
Small ; .5
When ADH is absent, H20 is trapped in the — and —, even though there is a large osmotic force for H20 movement.
distal tubule and collecting duct
When ADH is absent, the urine osmolality may decrease to — mOsm because salts are reabsorbed in the distal tubule and collecting duct and water is not.
50
When circulating levels of ADH are —, a large volume (up to —ml/min or — ml/kg/hr) of dilute urine (— - — mOsm) is formed.
Low ; 25 ; 25 ; 50-100
5 step responses following a decrease in body fluid osmolality:
- The hypothalamic nuclei swell, and a decrease in nerve impulse frequency in the hypothalamic-
hypophyseal tract results. - There is a decrease in ADH release.
- With reduced circulating levels of ADH, the distal tubules and collecting ducts become relatively
impermeable to H20. - The decrease in H20 reabsorption from the distal tubules and collecting ducts results in the production of large volumes of dilute urine.
- The increased H20 excretion causes body fluid osmolality to return to normal.
6 step responses following an increase in body fluid osmolality:
- The hypothalamic nuclei shrink, and an increase in nerve impulse frequency in the hypothalamic-hypophyseal tract occurs.
- There is an increase in ADH release. A 2% increase in osmolality (from 300 to 306 milliosmoles per kg)
is sufficient to stimulate the release of large quantities of ADH. - ADH increases the permeability of the distal tubules and collecting ducts to H20.
- The increased H20 reabsorption from the distal tubules and collecting ducts results in the excretion of small volumes of highly concentrated urine.
- Steps 1-4 serve to conserve existing body H20 and to prevent further increases in osmolality.
- The increased body fluid osmolality also triggers the sensation of thirst. H20 ingestion causes the
osmolality to return to normal.
the body corrects a hyperosmotic state by adding — to the extracellular fluid until the osmolality is restored to normal.
ingested water
the body corrects a hypo-osmotic state by increasing renal excretion of —, thereby removing — from the extracellular space until osmolarity is restored to normal.
water ; water
Sodium intake and excretion are — important in regulating extracellular fluid osmolality because significant changes in body sodium content take a long time to be achieved.
not
it would take — days to excrete enough sodium to correct a hyperosmotic state, but only — to — hours are required to dilute the extracellular fluid by ingesting water.
three ; one to three
+ADH: Urine osmolality and urine volume
1200-1500 mOsm and 0.5 mL/kg/hr (low)
-ADH: Urine osmolality and urine volume
50-100 mOsm and 2-25 mL/kg/hr (high)
What are the 2 causes of diabetes insipidus?
- Failure of ADH synthesis or ADH release (most common cause)
- Insensitivity of the distal tubules and collecting ducts to ADH (nephrogenic)
Inappropriate secretion of — can occur as a result of surgery or any of several diverse pathological
processes including intracranial tumors, hypothyroidism, porphyria, and small (Oat’s) cell carcinoma of the lung
ADH
An inappropriately increased urine sodium concentration and urine osmolality in the presence of hyponatremia and decreased plasma osmolality are virtually diagnostic of —.
inappropriate ADH secretion
The amount of — in the body is the major determinant of extracellular fluid volume.
sodium
— follows sodium.
Water
When the amount of — in the body increases,
osmolality increases.
sodium
With an — in osmolality, thirst mechanisms are activated and water is ingested.
increase
The primary event in increasing extracellular volume is the increase in body — content.
sodium
When the amount of sodium in the body decreases, ADH output is — and water excretion —.
decreased ; increases
— is the most important hormone for regulating extracellular fluid volume.
Aldosterone
sodium content (sodium load) determines — fluid volume.
extracellular
— (also known as —) is released from the right atria and also acts on the kidney to increase sodium excretion.
Atrial natriuretic peptide (atrial natriuretic factor)
Sodium excretion — when glomerular filtration rate increases and — when glomerular filtration rate decreases.
increases ; decreases
What are the 3 determinants of sodium excretion?
- GFR
- Aldosterone
- Atrial natriuretic factor
What are the 3 mechanisms to increasing Na excretion?
- Increase GFR
- Decrease aldosterone
- Increase atrial natriuretic factor (peptide)
What are the 3 mechanisms to decreasing Na excretion?
- Decrease GFR
- Increase aldosterone
- Decrease atrial natriuretic factor (peptide)
Aldosterone is a hormone produced in the zona glomerulosa of the —.
adrenal cortex
Aldosterone acts on the late — and — (primarily the —) to alter two renal tubular functions simultaneously.
distal tubule and collecting duct ; collecting duct
Aldosterone — the rate of Na reabsorption from the late distal tubule and collecting duct and thereby — the rate of Na excretion.
increases ; decreases
Aldosterone — the rate of K secretion into the late distal tubule and collecting duct and thereby — the rate of K excretion.
increases ; increases
Na reabsorption occurs from — segment of the renal tubule in the presence of aldosterone.
each
The bulk of the filtered Na is reabsorbed from the — (67%) and — (25%), but there also is significant reabsorption in the — and — (7.2%) if aldosterone is present.
proximal tubule ; ascending limb of Henle’s loop ; late distal tubule and collecting duct
Na reabsorption in the ascending limb of Henle’s loop occurs through a channel that simultaneously reabsorbs — and —.
K+ and CI-
Na secretion in the descending limb of Henle’s loop is —.
passive
Na reabsorption is an — process (—) in the proximal tubule, distal tubule and collecting duct.
active (energy-requiring)
Without aldosterone, about 8% of the filtered Na may be excreted because the — and — are importable to Na.
Distal tubule and collecting duct
When sodium intake is high, body sodium content increases, and body fluids become concentrated.
ADH output — to conserve existing water, and thirst causes water ingestion, which restores osmolality but expands fluid volume.
increases
The major consequences of sodium retention (increased content/amount of sodium) are extracellular fluid volume — (—) and a tendency for arterial blood pressure to —-.
expansion (hypervolemia) ; increase
Hypervolemia is corrected by — the renal excretion of sodium.
increasing
Sodium excretion is increased because: (a) GFR —, (b) renin release —, and (c) output of atrial natriuretic peptide —. Water is excreted along with the sodium to keep body fluid osmolality at 300 mOsm. This process of correcting a hypervolemic state takes several days.
increases ; decreases ; increases
When sodium intake is low, body sodium content (amount) decreases, and body fluids become dilute.
ADH output —, and a dilute, high-volume urine is formed. Osmolarity is restored to normal, but fluid volume is contracted.
decreases
The major consequences of sodium loss (decreased content/amount of sodium) are fluid volume — (—) and a tendency for a — in arterial blood pressure.
contraction (hypovolemia) ; decrease
