Urinary System (Renal Exam 1) Flashcards
Maintaining homeostasis requires the regulation of the composition, pH, and volume of body fluids within…..
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normal limits
The urinary system removes and excretes metabolic wastes and substances in excess, __________ containing compounds from protein metabolism, and foreign substances such as pharmaceuticals and their metabolites
N and S
The kidneys assist in regulation of RBC production via ______ and regulation of blood pressure via _____, and calcium ion absorption
EPO, RAAS
What are some of the many functions of the renal system?
-excretion of metabolic wastes and foreign chemicals
-regulation of water and electrolyte balances
-regulation of body fluids through osmolality/osmolarity and electrolyte conc.
-regulation of arterial pressure
-regulation of acid-base balance
-secretion, metabolism, and excretion of hormones
-control rate of RBC production with EPO
-gluconeogenesis
What organs are involved in the renal system?
-2 kidneys
-2 ureters
-1 urinary bladder
-1 urethra
The kidneys lie on either side of the vertebral column high in a depression on the posterior abdominal wall. Kidneys are retroperitoneal (behind the peritoneum). The L kidney is higher than the R kidney. Why?
R kidney is lower bc of the liver
What is the other name for adrenal gland?
suprarenal gland
The right adrenal gland drains into the….
IVC directly
***note: this is bc the R adrenal gland needs direct access to major circulation for hormone delivery to target organ. The right side is closer to the IVC for direct access
The left adrenal gland drains into the….
renal vein and then IVC
What is secreted by the adrenal medulla?
NE and epi
What are the features of the kidney structure?
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-convex lateral surface
-concave medial surface w/ hilum
-renal sinus
-renal pelvis (major and minor calyces)
-renal medulla (composed of renal pyramids)
-renal cortex (renal columns)
-renal capsule
The papillary/collecting duct drains urine into the….
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minor calyx
The minor calyx drains urine into major calyx. Where does urine go after major calyx?
renal pelvis
What is the most common type of nephron?
cortical nephrons
The aorta branches into the renal artery which goes into kidneys. What is the blood flow through here?
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renal a. > segmental a.> interlobar a.> arcuate a.> interlobular a. (also known as cortical radiate a.)> afferent arteriole> glomerular capillaries > efferent arteriole> peritubular capillaries associated with convoluted tubules OR vasa recta associated with loop of henle
The capillary bed filters….
plasma
What is the venous blood flow starting from the vasa recta and peritubular capillaries of the kidneys?
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peritubular capillaries and vasa recta> interlobular v. (also known as cortical radiate v.)> arcuate v.> interlobar v.> renal v.> IVC
Which arteriole leaves the capillary bed?
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efferent arteriole
What captures the filtrate from plasma?
glomerular capsule
What is the first capillary bed in the nephron?
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glomerulus
A renal a. enters each kidney through the _______ and continues to branch to the nephrons (functional units)
hilum
What is another name for interlobular arteries or veins?
cortical radiate arteries or veins
What is another name for the glomerular capsule?
Bowman’s capsule
T/F: the descending and ascending limb of the loop of henle have a differential regulation of water and ions
true, they have different permeability for water and ions
What are the 2 types of nephrons?
1) cortical nephrons (short)
2) juxtamedullary nephrons (long, go to medulla)
Which nephrons are important for regulating water balance?
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juxtamedullary nephrons bc they’re long and sit low in the cortex
What are the 2 parts of a nephron?
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1) renal corpuscle
2) renal tubule
What are the 2 parts of a renal corpuscle?
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1) glomerulus (capillaries)
2) glomerular (Bowman’s) capsule
What are the 2 portions of the glomerular/Bowman’s capsule and what cells are here?
-parietal and visceral portions
-podocytes are in the visceral layer
The renal tubule extends from the glomerular capsule to the….
collecting duct
What are the parts of the renal tubule in order?
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1) PCT
2) nephron loop/loop of henle
-descending limb
-ascending limb thin segment
-ascending limb thick segment
3) DCT
4) connecting tubule
5) cortical-medullary collecting tubule
6) collecting duct
The DCT of several nephrons empty into the….
collecting ducts (which will continue to the medulla and join other collecting ducts to drain through the renal papillae into a minor calyx)
Where does the majority of filtration and absorption occur?
PCT
For cortical nephrons, they have a short loop of henle and glomerulus further from the corticomedullary junction but has the vascular bed around the PCT and DCT. The efferent arterioles supply the….
peritubular capillaries
For juxtamedullary nephrons, they have a long loop of henle and glomerulus closer to the corticomedullary junction. The efferent arterioles supplies the….
vasa recta
T/F: there is temporary storage in the urinary bladder and then it is emptied through the urethra
true
Substances move from the glomerular capillary blood into the glomerular capsule. What molecules can/are filtered through glomerulus?
water and small dissolvable molecules or ions
(large molecules such as large proteins and cells remain in the blood because they are too large to pass through the glomerular filtration membrane)
Glomerular capillaries are way more permeable than other capillaries. Why?
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because glomerular capillaries are fenestrated
What should not be in urine?
-blood
-glucose
-protein
Filtrate is formed as substances and ________ filter from the glomerulus into the glomerular capsule
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plasma
T/F: initial filtrate has different composition from plasma and tissue fluid
FALSE, its the same composition
What acts like a barrier for fenestrations in sinusoidal caps?
basement membrane
In the first capillary bed of the nephron, filtration will not occur without….
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the specific fenestrated type of capillary
What does filtrate include?
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-water
-glucose
-AAs
-ions
-urea
-hormones
-vitamin B and C
-ketones
-small amounts of protein
basically- anything small
(for a normal person, most of this needs to be absorbed)
What are the 3 parts of the filtration membrane?
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1) fenestrated capillary endothelium
2) basement membrane fused basal lamina
3) podocytes of visceral membrane of capsule - slit pore
The top of each nephron’s ascending limb passes next to its afferent arteriole. At this location, cells are specialized to form the….
juxtaglomerular (JG) apparatus
What 2 cell types that make up the JG apparatus?
1) macula densa (in the ascending limb)
2) JG cells (vascular smooth muscle cells of the afferent arteriole)
What cells synthesize/secrete renin?
granular cells
What triggers renin to be secreted when BP needs to be increased?
afferent arteriole
The JG apparatus has what receptors?
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mechanoreceptors (check BP) and osmoreceptors (Check osmolality)
How do cells communicate in JG apparatus?
through gap junctions
The main function of the nephrons and collecting ducts is to control the composition of body fluids and remove wastes from the blood, the product being urine. What does urine contain?
-wastes
-excess water
-electrolytes
Urine is the final product of what 4 processes?
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1) glomerular filtration
2) tubular reabsorption
3) tubular secretion (from 1st pass effect, will be secreted into urine)
4) excretion/ concentration and dilution (how concentrated urine is)
How much cardiac output is brought to the kidneys?
25%
filtration - reabsorption + secretion = ?
excretion
If theres only filtrate, will anything be absorbed or secreted?
no
What causes filtration with only partial reabsorption?
glucose overload (diabetic patients will have this)
What is normal urine formation?
filtration with complete reabsorption
In most systemic capillaries, filtration predominates at the ________ end and osmotic reabsorption predominates at the ___________ end
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arteriole, venular
Where does most tubular reabsorption occur?
PCT
Which substance makes up most of the plasma contents?
sodium
T/F: plasma and glomerular filtrate concentrations will be the same for a normal person
true
What substances get secreted into urine?
-potassium
-calcium
-magnesium
-chloride
-urea
-uric acid
-creatinine
What substances get reabsorbed and will not end up in urine for a normal person?
-sodium
-bicarbonate
-glucose
High glucose filtration exceeds tubular reabsorption capability and results in….
glucose in urine (diabetic patients)
Glomerular filtration rate (GFR) is directly proportional to the….
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net filtration pressure (hydrostatic pressure + osmotic pressure)
force favoring filtration (glomerular capillary hydrostatic pressure aka blood vessel pressure) - forces opposing filtration (capsular hydrostatic pressure and glomerular capillary osmotic pressure) = ?
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net filtration pressure
Normally, the glomerular net filtration pressure is ________ causing filtration
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positive
The main force that moves substances by filtration through the glomerular capillary wall is hydrostatic pressure of the blood inside because….
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afferent arteriole has larger diameter than efferent arteriole
GFR remains relatively constant through a process called….
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autoregulation
Autoregulation can be overridden when GFR….
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increases
T/F: less flow= less filtration
true
What are the mechanisms responsible for keeping the GFR constant?
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-autoregulation
-increased sympathetic impulses that decrease GFR by causing afferent arterioles to constrict
-RAAS (ang 2 is a vasoconstrictor and stimulates aldosterone secretion from the adrenal cortex. Aldosterone increases sodium reabsorption in the renal tubule which osmotically increases water reabsorption, resulting in increased blood volume)
-efferent arteriole vascular resistance has a biphasic affect on glomerular filtration rate
Which hormone affects the sodium causing an increase in GFR (minor) and increase in sodium water excretion in response to atrial stretch and increased blood volume?
atrial natriuretic peptide (ANP)
The liver is constantly producing what zymogen for RAAS?
angiotensinogen
Which organ is renin secreted from for RAAS?
kidney
In RAAS, angiotensinogen with renin makes….
Ang 1
What enzyme converts Ang 1 to Ang 2 in the lungs and releases it to bloodstream for RAAS?
angiotensin converting enzyme (ACE)
Which Ang is a strong vasoconstrictor?
Ang 2
What does Ang 2 do?
-vasoconstriction in adrenal cortex
-increased aldosterone secretion
-increased ADH secretion
-increased thirst
Substances move from the renal tubules into the intestinal fluid where they diffuse into the peritubular capillaries. Most tubular reabsorption (70%) occurs in the PCT because its lined with….
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microvilli so this increases SA and allows for more carriers, channels, and active transport pumps
What are the 3 types of transport that happens in tubular reabsorption?
1) active transport
2) osmosis
3) endocytosis
Renal plasma threshold is reached when there is….
more filtered substance in the filtrate than the active transport mechanism - for reabsorption to be able to manage
High levels of solutes in filtrate causes __________ pressure and water to remain in urine. On solute reabsorption, water follows
osmotic
Endocytosis is only done with….
small proteins
Water reabsorption occurs passively by osmosis and is closely associated with _________ reabsorption of sodium
active
(small changes in the tubular reabsorption of sodium and water result in large changes in urinary excretion of these substances)
As ions are reabsorbed in the PCT, water follows through osmosis resulting in an ______________ at the end of the PCT peritubular capillaries
isotonic filtrate
Substances move from the plasma of the peritubular capillaries into the fluid of the renal tubules. What substances undergo active transport here?
-drugs
-ions like bicarb
-H+ (for regulating pH of body fluids)
Sodium ions are reabsorbed by what transport mechanism?
secondary active transport
As conc. of ions/solute increases in plasma, __________ pressure increases
osmotic
Water moves from proximal tubule to capillary by what transport mechanism?
osmosis with aquaporins
The hilum is located along the concave medial border where blood vessels and nerves enter and exit the kidney. It also serves as the point of exit for the renal pelvis, which transports urine to the….
ureter
_____ blood volume will allow renin to be secreted from the kidney into the blood stream
Low
Water is polar and impermeable to the cell membrane, so it has to go through which route?
paracellular route
The electrochemical gradient during tubular reabsorption is attracted to which ion?
k+
DCT and collecting duct are impermeable to water in the absence of….
ADH and aldosterone
The paracellular route involves movement through leaky tight junctions particularly in the…
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PCT
chloride, calcium, potassium, and urea will go through a paracellular route or a transcellular route?
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paracellular route
What substances diffuse by the transcellular route?
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lipid-soluble substances
Glucose will go through a symporter with what ion in tubular reabsorption?
Na+
H+ will go through an antiport with what ion in tubular reabsorption?
Na+
What hormones affect the solute conc. of urine (particularly sodium)?
aldosterone and ANP
The ability of the kidneys to maintain the internal environment rests in a large part on their ability to….
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conc. urine by reabsorbing large volumes of water
Where is water regulated due to impermeability?
DCT and collecting duct
if ADH is present, then they will become permeable to water and water will be reabsorbed by osmosis into the extremely hypertonic medullary interstitial fluid and into capillary
(a countercurrent mechanism in the nephron loops (the descending and ascending limbs) ensures that the medullary interstitial fluid becomes hypertonic- the countercurrent multiplier. The vasa recta also contributes as a countercurrent mechanism)
Which limb is permeable to water but not solutes?
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descending limb
Which limb is impermeable to water but is permeable to NaCl and will undergo passive transport through transporter?
thick ascending limb
The differences between descending and ascending limb permeability sets up…
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a concentration gradient
The vasa recta is an exchanger and allows for SLOW perfusion with an intravascular osmotic equilibrium. This is nutrient flow to cells. What happens to conc. gradient here?
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theres no change in conc. gradient here!
What is another name for anti-diuretic hormone (ADH)?
arginine vasopressin (AVP)
With ADH, conc. of water in blood increases or decreases?
decreases (so the osmolarity of blood increases)
An increase in osmotic pressure of body fluids stimulates __________________ in hypothalamus, which will release ADH into the posterior pituitary capillary bed
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osmoreceptors
Circulating ADH goes to the kidney and stimulates DCT and collecting ducts to increase water reabsorption via….
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aquaporin synthesis and insertion into luminal membrane
What protein receptor is used in RAAS?
G protein receptor
What are the 2 ways to get ADH?
1) hypothalamus
2) RAAS
What does increased ADH do to urine?
makes it more concentrated (urea is also transported via facilitated diffusion out of the collecting duct and will result in even more concentrated medulla and urine)
Ang 2, in response to low BP stimulates _________________ secretion
hypothalamic ADH
ADH in response to _____________ osmotic pressure, _________________ blood volume and can result in hypotension
increased, decreases
In the PCT, what molecules are actively transported (secondary active transport)?
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-Na+
-glucose
-AAs
In the PCT, what molecules are passively transported?
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water and ions
Does the PCT regulate blood pH?
yes
Where does filtrate become increasingly concentrated as water leaves by osmosis/aquaprorins?
descending limb of the loop of henle
Where does filtrate become increasingly more dilute as salt is being reabsorbed?
ascending limb of the loop of henle
In the DCT, sodium reabsorption is regulated by….
aldosterone
In the DCT, calcium reabsorption is regulated by….
parathyroid hormone (PTH)
In the DCT what is sodium cotransported with?
Cl-
In the collecting duct, water is regulated by…..
ADH
In the collecting duct, Na+/K+ are regulated by….
aldosterone
Does the collecting duct regulate blood pH?
yes
Urea is a byproduct of….
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AA catabolism
Urea contributes to the reabsorption of water from the….
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collecting duct
What provides most of the osmotic conc. of medullary interstitial fluid?
urea
Uric acid is a product of….
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nucleic acid metabolism
T/F: active transport completely reabsorbs the filtered uric acid
true
What does urine usually contain besides mostly water?
-urea
-uric acid
-creatinine
may have trace amounts of AAs and electrolytes
What is renal clearance?
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rate at which a chemical is removed from the plasma
Renal clearance indicates what?
kidney efficiency
What are the 3 tests for renal clearance?
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1) inulin clearance test (filtered at the glomerulus, not reabsorbed or secreted)
2) creatinine clearance test
3) para-aminohippuric acid (PAH) test
note: these tests are used to calculate the GFR
After forming along the nephrons, urine passes the collecting ducts to openings of the renal papillae and enters the minor and major calyces, which then passes through renal pelvis and enters into the ureters and then urinary bladder. What carries urine out of the body?
the urethra
The ureters extend downward posterior to the parietal peritoneum and run parallel to the vertebral column. They join the _________________ in the pelvic cavity
urinary bladder
What are the 3 layers of a ureter?
1) inner mucous coat
2) middle muscular coat
3) outer fibrous coat
An obstruction, such as kidney stone (or renal calculus) in a ureter will trigger the __________________. It is strong peristaltic waves in the obstructed ureter and causes reduced urine production in affected kidney
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uretrorenal reflex
What epithelium makes up the mucosal layer of the ureter?
transitional epithelium-urothelium
Peristalsis of the ureters requires what muscle layers?
circular (inner) and longitudinal (outer) layer
The urinary bladder is a hollow, distensible, muscular organ located within the pelvic cavity, posterior to the pubic symphysis and inferior to the parietal peritoneum. It contracts the anterior walls of the _________________ in the female and lies posteriorly against the _________ in the male
uterus and vagina, rectum
The urinary bladder has an area known as __________, which is at the floor of the bladder and has 3 openings. 2 openings go to ureters and 1 goes to urethra
trigone
What are the 4 layers of the urinary bladder?
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1) mucosal coat (inner)
2) submucosa coat
3) muscular coat (detrusor m.)
4) serous coat (outer, upper surface only)
Smooth muscle fibers comprise the _____________ which is the muscle of the bladder wall
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detrusor m.
Which sphincter surrounds the neck of the bladder?
internal urethral sphincter
The mucosal coat has several layers of transitional epithelium in the ureters. The thickness changes with….
distention
The ___________ is a tube that conveys urine from the urinary bladder to the outside of the body. Its wall is lined with a muscle membrane and has a thick layer of longitudinal smooth muscle cells
urethra
In females, the external urethral orifice is __________ to the vaginal orifice
anterior
Which gender has a dual function for both urination and reproduction in the urethra?
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males
What are the 3 sections of the male urethra?
1) prostatic urethra
2) membranous urethra
3) penile urethra
urine leaves the urinary bladder by micturition or __________________
urination reflex
