More lecture 10qs Flashcards
The renal artery gives rise to how many segmental arteries?
5
Where does water in urine come from?
Plasma
How do the kidneys protect acid base balance?
By conserving or excreting H+ ions
What do the kidneys activate?
Vitamin D
How are kidneys involved with blood cell regulation?
Produce EPO
What is made of striated triangles called renal pyramids?
Renal medulla
One of what supplies each nephron and delivers blood to each glomerulus?
Small afferent arterioles
Only place in the body where capillaries drain into arterioles rather than veins is where?
Glomerular capillaries
What is the juxtaglomerular apparatus?
Specialized region made of vascular and tubular cells
All nephrons originate where?
Cortex
What type makes up 80% of nephrons?
Cortical
The glomerulus lies in inner cortex of what nephrons?
Juxtamedullary
Peritubular capillaries of ____________________ nephrons form vasa recta
juxtamedullary
How much filtrate is formed each day?
180L
______% of the plasma that enters glomerular capillaries is filtered into the Bowman’s capsule
20%
Of the 180L of filtered plasma, 178.5L is ________________
reabsorbed
What do the 3 layers fluid passes to enter Bowman’s capsule retain? What do they let pass?
Retain blood cells and plasma proteins, pass H2O and smaller molecules
True or false: the fenestrations in the glomerular capillaries do not let RBCs out
True
Where are glycoproteins found?
In the basement membrane (b/t glomerulus and bowman’s capsule)
1% of proteins that slip through are degraded into amino acids in __________________ and reabsorbed, thus normal urine is protein free
proximal tubule
Podocytes are found where?
Inner layer of Bowman’s capsule
True or false: No local energy is used to move fluid across the membrane into Bowman’s capsule
True
What 2 things does glomerular capillary blood pressure depend on?
1) Heart contraction
2) Resistance in afferent and efferent arterioles
True or false: glomerular capillary blood pressure only depends on afferent arteriole pressure
False; both afferent and efferent
Glomerular capillary pressure is _____________ than other capillaries
higher
What concentration gradient establishes tendency of water to move from Bowman’s capsule into glomerulus?
Plasma proteins
What does increased arterial blood pressure do?
Increase blood flow into glomerular capillaries
What pressure tends to push fluid out of capsule (opposing filtration)?
Bowman’s capsule hydrostatic pressure
GFR depends on what 3 things?
1) NFP
2) Glomerular surface area
3) Glomerular permeability
What is a measure of how much blood passes through glomeruli each minute?
GFR
Can burns increase or decrease GFR?
Increase
Can dehydration increase or decrease GFR?
Decrease
Urinary tract obstruction (kidney stone, enlarged prostate) can increase what pressure?
Bowman’s capsule hydrostatic pressure
MAP and afferent arteriole resistance largely determine what?
Glomerular capillary blood pressure
The body regulates GFR by adjusting what pressure?
Glomerular capillary blood pressure
Two control mechanisms regulate GFR by regulating ______________________ of ________________ arterioles
radius (resistance); afferent
What is extrinsic control of GFR also called?
Sympathetic control
What prevents momentary changes in BP from changing GFR?
Autoregulation (intrinsic)
Extrinsic controls do what to autoregulatory responses?
Override them
Are baroreceptors or chemoreceptors involved in GFR control?
Baroreceptors
Baroreceptor reflex response achieves what?
Sympathetic control of GFR
1) When baroreceptors detect a fall in BP, what does the brainstem then do?
2) What two things does this then increase?
1) Initiates sympathetic stimulation of heart and vessels
2) Cardiac output and peripheral resistance (incl. of afferent arteriole)
Which arterioles are more sympathetically innervated?
Afferent
What happens when the baroreceptors detect low BP?
Sympathetic vasoconstriction is reduced
Substances being returned from tubular lumen into peritubular capillaries is called what?
Tubular reabsorption
To leave tubular fluid, a substance must cross what?
Luminal membrane [of tubular cell]
What is within tubular cells?
Cytosol
What part of tubular cells must be crossed to enter IF?
Basolateral membrane
How do substances enter plasma?
Diffusing through IF, then penetrating capillary wall
List 3 things that require active transport during reabsorption
Glucose, amino acids, electrolytes
80% of the energy spent by kidneys is used for ______ transport
Na+
True or false: all segments of the tubules transport the same amounts of Na+
False; different segments of the tubules transport differing amounts of Na+
Where is the Na-K ATPase pump?
Basolateral membrane of tubular cells
How is Na+ reabsorbed?
Na-K pump transports Na+ out of tubular cell into lateral space where it builds up
Once it’s pumped out for reabsorption, sodium diffuses _[up/down]___concentration gradient into interstitial fluid and then peritubular capillary
down
Na+ and Cl- account for _____% of ECF osmotic activity
90%
When Na+ load is __high/low___, it “holds” water and fluid volume expands
high
Expansion of ________ volume increases BP, reduction decreases BP
plasma
Na+ regulating mechanisms regulate what pressure?
Arterial blood pressure
The renin-angiotensin-aldosterone system (RAAS) is the most important system for the regulation of what molecule?
Na+
What secretes renin?
Juxtaglomerular apparatus
True or false: the kidneys don’t have any baroreceptors
False; have intrarenal baroreceptors
Baroreceptor reflex sympathetic activity stimulates _______ secretion
renin
Falling NaCl, fluid volume, and BP trigger the kidneys to secrete what?
Renin
What produces angiotensinogen?
Liver
What converts angiotensinogen into angiotensin I?
Renin
What converts angiotensin I into angiotensin II? Where does it come from?
Angiotensin converting enzyme from lungs
1) What does angiotensin II do to the heart? (2 things)
2) What does it increase outside the heart? (3 things)
1) Increases HR and contractility
2) Vasopressin, thirst, and arteriolar vasoconstriction
What does aldosterone do?
Increase Na+ reabsorption by tubules (Cl- follows)
Someone with a high BNP usually has what?
HF
ANP and BNP are produced by the heart and inhibit what?
Na+ reabsorption
ANP and BNP are released when heart muscles detect what?
stretch
The concentration at which tubular maximum is reached is called ______________
renal threshold
True or false: Plasma membrane carriers are specific to the substance being transported
True
Once transported into tubular cell, what passively diffuse down gradients into plasma?
Nutritionally important molecules
What osmotically follows Na+?
H2O
What is reabsorbed down electrical gradient created by Na+?
Cl-
Urea has a limited permeability of which only allows ____% of urea to be reabsorbed
50%
Urea is from ____________ breakdown
protein
What are the 4 most important things that are secreted into tubules?
H+, K+, organic anions and cations
Increased acidity increases ______ ion secretion.
H+
What ion is tightly controlled by the kidneys?
K+
What do prostaglandin and epinephrine have in common?
They’re organic ions that are secreted into tubules (tubular secretion) because they need to be removed to avoid prolonged activity
Many foreign compounds are organic ions including what 3 things?
Food additives, drugs, environmental pollutants
Is flow in the vasa recta the same as in the loops of henle or not?
Not the same; countercurrent
What allows water to be reabsorbed?
Vertical osmotic gradient
Countercurrent multiplication is a _________ feedback loop that ends with a high concentration at the ___________ of the loop of Henle
positive; bottom
What part of the loop of Henle has Na-K pumps?
Ascending limb
Why does water leave the descending limb?
Because of the sodium that leaves the ascending limb
Does the ascending or descending limb have higher concentration?
Descending
What direction does high concentration fluid in the loop of henle go?
Down
What ascends the ascending loop of henle?
Less concentrated fluid
What is secreted when ECF is too concentrated (H2O deficit)?
ADH/ vasopressin
What two things are only permeable to H2O in the presence of vasopressin?
Distal and collecting tubules
What detects hypertonicity?
Hypothalamus
The bladder is richly supplied with _____________________ fibers which cause contraction which empties urine via urethra
parasympathetic
What is the last part of the bladder called?
Internal urethral sphincter
What does parasympathetic action inhibit?
Motor neurons of external urethral sphincter
Give 3 side effects of uremic toxicity (a symptom of kidney failure)
Platelet dysfunction, nerve damage, GI symptoms
Inability to secrete H+ causes what?
Metabolic acidosis
Blood pressure issues (edema (excess) or hypotension/ shock (deficiency)) can all result from what effect of kidney failure?
Sodium imbalance
What increases cardiac and neural excitability?
K+ retention (renal failure side effect)
The “internal pool” of a substance is the amount of that substance in the ECF, or ICF?
ECF
______ composes 2/3rds of body water, ________ 1/3rd
ICF; ECF
Plasma and IF are both types of what?
ECF
True or false: lymph and transcellular fluids (CSF, synovial fluid, pleural fluid, etc.) are major considerations in fluid balance
False; they’re minor
ECF components (plasma and IF) are separated by walls of what?
Blood vessels
Transfer of H2O between plasma and IF is governed by what?
Imbalances across the capillary walls
Hydrostatic pressure of what are low and fairly constant?
ECF and ICF
All exchanges of H2O between ICF and external world must occur through what?
ECF
If plasma’s volume or composition is changed, then the volume and composition of what is also changed?
IF
Control mechanisms acting on plasma indirectly regulate what?
IF (and thus ECF volume as a whole)
What are the two factors in regulating fluid balance in the body?
ECF volume and osmolarity
ECF ___________ is controlled by salt balance
volume
ECF ___________ is controlled by water balance
osmolarity
Increased ECF osmolality causes what to be secreted?
Vasopressin
What are the short term and long term controls of ECF volume?
Short term controls: baroreceptor reflex, automatic fluid shifts between plasma and IF due to hydrostatic pressures
Long term controls: kidneys regulate output, thirst regulates input
What are responsible for ICF osmolarity?
K+ and anionic proteins
Loss of ECF H2O will lead to ________tonic ECF
hypertonic
True or false: Any change of H2O (that is not accompanied by a comparable change in solutes) will lead to a change in ECF osmolarity
True
How does the body regulate ECF osmolarity? (2 ways)
Vasopressin and fluid shifts
True or false: water input and output should be equal
True
What stimulates thirst and vasopressin?
Angiotensin II
What can suppress/stimulate vasopressin and thirst?
Left atrial volume receptors
Increased ECF osmolarity leads to increased thirst and increased vasopressin because of what receptors?
Hypothalamic osmoreceptors
Elevated renal capillary hydrostatic pressure increases _____ ion excretion
Na+
Sodium deprivation does not lead to _____ ion loss by the kidneys
K+
Diuretics promote ____ ion excretion by the kidney
Na+
What is regulated by the renin-angiotensin-aldosterone system and atrial natriuretic peptide?
Extracellular Na+
What ion balance is sensitive to blood chemistry, hormones, drugs and pathological conditions?
K+
Thiazide diuretics increase the reabsorption of what ion?
Ca+
True or false: Most of the Ca2+ filtered through the glomeruli is reabsorbed in the proximal convoluted tubule
True
High plasma ________ levels have a sedative effect and may cause cardiac arrest.
Mg2+
Control of Ca+ excretion occurs where? (2 places)
The loop of Henle and distal nephron
What is the major site for the reabsorption of filtered Mg2+? What does 25% of it?
Loop of Henle; PCT does 25%
Low plasma ______ ion concentration causes neuromuscular hyperirritability and cardiac arrhythmias
Mg2+
The PCT is the major site of reabsorption of what ions?
Ca2+ and phosphate
99% of ____ is in bones, and so is 80% of _______
Ca2+; phosphate
PTH inhibits the reabsorption of _______________ but stimulates the reabsorption of ___________________
phosphate; calcium
What in the urine is an important pH buffer?
Phosphate
Chronic renal disease often leads to an elevated plasma __________ and decreased plasma __________
phosphate; calcium
