Clin Chem Exam #3 Renal Physiology & Npn Compounds

Front 1

The renal system is composed of what 4 things?

Back 1

2 kidneys, 2 ureters, 1 bladder, 1 urethra

Front 2

the main structural part of urinary system, responsible for the formation of urine

Back 2

kidneys

Front 3

filter units of kidneys, designed for synthesis of urine

Back 3

nephrons

Front 4

The transport methods in the ureters are by?

Back 4

gravity and peristalsis of smooth muscle

Front 5

pale outer region of the kidney

Back 5

cortex

Front 6

dark inner region of the kidney

Back 6

medulla

Front 7

the apex ends in the _________ which merges to form the __________

Back 7

renal papilla; renal pelvis

Front 8

Allows:
1.Regulation of the water and electrolyte content of the body.
2.Retention of substances vital to the body such as protein and glucose
3.Maintenance of acid/base balance.
4.Excretion of waste products, water soluble toxic substances and drugs.
5.Endocrine functions.

Back 8

1. glomerular filtration
2. tubular reabsorption
3. tubular secretion

Front 9

Fundamental urine-producing unit of the kidney

Back 9

nephron

Front 10

Glomerulus
Bowman's capsule
PCT
Loop of Henle
DCT
Collecting duct

Back 10

Components of nephron

Front 11

Tuft of capillaries where filtration occurs

Back 11

glomerulus

Front 12

surrounds glomerulus, and collects filtrate

Back 12

Bowmans capsule

Front 13

adjusts volume and concentration of urine

Back 13

collecting ducts

Front 14

-filters incoming blood
-first part of the nephron
-strains cellular elements and large molecules to from blood to produce a "ultra free" protein filtrate

Back 14

glomerulus

Front 15

allows free movement of electrolytes, water, and small dissolved solutes. Filtration of large molecules is limited by their size, shape, and electic charge.

Back 15

glomerulus

Front 16

-fenestrations that line the glomerular blood vessels
-provide some barrier to negatively charged large molecules

Back 16

capillary endothelium

Front 17

semi permeable membrane that has a high concentration of negative charges due to glycoprotiens and sialic acid residues

Back 17

basement membrane

Front 18

characteristic foot processes forming forming filtration slits

Back 18

podocytes

Front 19

filter factors in glomerular filtration include? (3)

Back 19

-cellular structure
-hydrostatic and oncotic pressure
-renin- angiotension- aldosterone system

Front 20

1200 ml/mn

Back 20

Renal blood flow

Front 21

The driving hydrostatic pressure of glomerular filtration is controlled by the afferent and efferent arterioles, and provided by arterial pressure

Back 21

juxtaglomerular apparatus

Front 22

balances oncotic pressure from unflitered protiens

Back 22

Glomerular filtration

Front 23

600-700 ml/mn

Back 23

renal plasma flow

Front 24

When there is a decrease in GFR, there is a resulting decrease in the fluid flow rate within the tubule

Back 24

Glomerular Tubular Balance

Front 25

In glomerular tubular balance, at the loop of henle there is a greater time for reabsorption of?

Back 25

sodium and chloride ions

Front 26

B/c of loop of Henle, there is a decrease in the number of sodium and cholride ions reaching the _________ and that is detected by the _______

Back 26

distal tubule; macula densa

Front 27

When ion decrease is detected by the macula densa what then happends?

Back 27

there is a decrease in the resistance in the afferant arteriole which results in an increase in renal blood flow

Front 28

The macula densa increases _____ release from the juxtaglomerular apparatus which stimulates _________ production causing constriction of the _____________

Back 28

renin; angiotension II; efferant arteriole

Front 29

consists of macula densa cells which are special distal tubular epithelial cells which detect chloride concentration and modified smooth muscle cells, juxtaglomerular cells, in the walls of the afferent and efferent arteriole

Back 29

Juxtaglomerular apparatus

Front 30

These cells produce renin

Back 30

Macula densa cells of the juxtaglomerular apparatus

Front 31

enzyme which converts plasma protein angiotension into angiotension I

Back 31

renin

Front 32

causes vasoconstriction and and increse in blood pressure

Back 32

angiotension II

Front 33

-causes water and sodium retention which together increse blood volume
-stimulated by the adrenal gland which is stimulated by angiotension II

Back 33

Aldosterone

Front 34

The aldosterone/angiotension I&II system is what kind of system?

Back 34

negative feedback system

Front 35

What is the stimulus in the negative feedback system in the regulation of renal blood flow?

Back 35

a fall in blood volume which leads to a fall in perfusion blood pressure in the kidneys

Front 36

When is the negative feedback system stopped?

Back 36

When blood volume, renal perfusion, and GFR improve

Front 37

Each nephron produces how many uL of filtrate a day? How much filtrate is produced by the kidneys every day?

Back 37

100 uL; 200 L

Front 38

% of flitrate reabsorbed by kidney tubules

Back 38

99%

Front 39

H2O
Na+, K+, Cl-, HCO3-, Ca++, Mg+, PO4, etc.
Glucose
Urea
Creatinine
Inulin

Back 39

Freely filtered glomerular filtrate

Front 40

partially filtered by glomerular filtrate

Back 40

albumin

Front 41

-immunoglobulins
-cells
-protien bound lipids and bilirubin
-large molecules
-negatively charged plasma proteins

Back 41

not filtered by glomerular filtrate

Front 42

___% of filtrate reabsorbed by renal tubules. __% excreted as urine

Back 42

99;1

Front 43

-substance combines with protien in renal tubular cells
-energy created allows substance to cross cell membrane back into bloodstream

Back 43

active transport in tubular reabsorption

Front 44

electrical potential/ concentration differences allow molecules to cross a membrane

Back 44

passive transport in tubular reabsorption

Front 45

Duties of tubular secretion (2)

Back 45

1. removal of waste products not filtered by the glomerulus
2. regulation of acid-base balance (secretion of hydrogen ions)

Front 46

-HCO3- ion filtered by glomerulus
-Filtered HCO3- returned to plasma via renal tubular secretion of H+ ions
-Excretion of H+ ions through ammonium ions

Back 46

Buffering excess acid formation in tubular secretion

Front 47

-cell- free filtrate; protein free in normal humans
-specialized cells that expand the surface area of its membrane and facilitate the handling of the bulk (60-80%) of reabsorption of the filtrate

Back 47

PCT

Front 48

Reabsorbs:
-75% of water, Na+ and Cl-,
-All (up to renal threshold) of glucose, amino acids and vitamins
-Almost all Ca+2, Mg+2, phosphate, HCO3-, SO4-
-All uric acid (later secreted) and some urea (BUN)
-small amount of protein (mainly albumin) and other small solutes

Back 48

PCT

Front 49

PCT reabsorption uses what kind of transport?

Back 49

active transport, except for water and chloride

Front 50

in response to osmotic gradients, and renal tubular permeability...

Back 50

reabsorption of water is passive

Front 51

In the PCT in renal threshold--concentration exceeds capacity...

Back 51

It is excreted into urine

Front 52

Movement of substances from peritubular capillaries to tubular lumen; tubular cell metabolism secretion

Back 52

PCT secretion

Front 53

excretes urea, creatinine, hydrogen ions, and drugs

Back 53

PCT secretion

Front 54

Product of kidney tubular metabolism

Back 54

PCT secretion

Front 55

summarize PCT secretion

Back 55

-initial filtrate entering PCT is isotonic with blood
-final filtrate leaving PCT(and entering loop of henle) is also isotonic~ although 75% reduced in volume.

Front 56

hairpin like loop between the PCT and DCT

Back 56

Loop of Henle

Front 57

Uses countercurrent flow (opposing flow both ascending and desceding)

Back 57

Loop of Henle

Front 58

water is removed by osmosis in

Back 58

the descending loop of henle

Front 59

sodium and chloride are reabsorbed in the

Back 59

ascending loop of henle

Front 60

is impermeable to water but actively reabsorbs sodium and chloride from filtrate into interstitial fluid surrounding the loops. This makes interstitial fluid

Back 60

ascending loop; hypertonic

Front 61

final fluid entering the distal tubule from the loop of henle is

Back 61

hypotonic

Front 62

also called the diluting segment

Back 62

ascending loop

Front 63

Differing permeability of ascending and descending loops maintains the high osmolality of the medulla and produces hyposmolal urine into the DCT. This process is known as

Back 63

countercurrent multiplier system

Front 64

initial filtrate entering the loop of henle is

Back 64

isotonic

Front 65

at the base of the loop of henle, the filtrate is very

Back 65

hypertonic

Front 66

final filtrate leaving the loop of henle enters the ____, and is _________, although 20-25% reduced in volume

Back 66

DCT; hypotonic

Front 67

by the time filtrate reaches the ___, the volume has been reduced from 200L/day to 2L/day

Back 67

DCT

Front 68

shorter than the PCT

Back 68

DCT

Front 69

Coiled tubule that connects to the collecting duct

Back 69

DCT

Front 70

In the DCT ~95% of __ and __ and 90% of _____ have already been reabsorbed

Back 70

Na; Cl; water

Front 71

makes small adjustments to acheive:
-electrolyte balance
-acid-base homeostasis
-action of hormones: aldosterone and ADH

Back 71

DCT

Front 72

-Hormone secreted by posterior pituitary gland
-Due to inc. blood osmolality; large loss of blood
-Stimulates water reabsorption via DCT tubules (normally impermeable to water)

Back 72

ADH

Front 73

-Hormone produced in adrenal cortex
-Influenced by the renin-angiotensin system (dec. blood flow or pressure in afferent arteriole/ dec. plasma Na)
-Stimulates Na reabsorption in the DCT and K, H+ secretion (linked to HCO3- regeneration and ammonia secretion)

Back 73

Aldosterone

Front 74

Final osmolality of urine is determined by ADH regulation of H2O reabsorption and Aldosterone (if present) action on Na+

Back 74

Collecting ducts

Front 75

___________ of kidneys where water is reabsorbed making plasma ________and urine concentrated

Back 75

Collecting ducts; hypotonic

Front 76

Chloride and urea are also reabsorbed

Back 76

Collecting ducts

Front 77

____ maintains increased medullary osmolality by diffusing down its concentration gradient into the medulla

Back 77

urea

Front 78

<400 mL/day

Back 78

oliguria

Front 79

<100 mL/day

Back 79

anuria

Front 80

>2000 mL/day

Back 80

polyuria

Front 81

intense and excessive thirst

Back 81

polydipsia

Front 82

used to monitor and assess renal function

Back 82

Non- protien nitrogen compounds (NPN)

Front 83

Arise from the breakdown of proteins and nucleic acids and include:
-Urea – (more than 75% of these compounds)
-Creatinine
-Creatine
-Uric acid
-Ammonia
-Amino acids

Back 83

NPN

Front 84

elevated levels of NPN compounds in blood

Back 84

Azotemia

Front 85

produced by liver, kidneys and pancreas from amino acids (arginine, glycine and methionine)

Back 85

creatine

Front 86

Creatine is transported in blood to other organs such as muscle where it is __________ to creatine phosphate (a high energy compound)

Back 86

phosphorylated

Front 87

A portion (~20 %/day) of free creatine in muscle spontaneously and irreversibly converts to its
_____________ creatinine

Back 87

anhydride waste product

Front 88

the amount of creatinine produced daily is fairly constant and proportional to

Back 88

muscle mass

Front 89

-Catalyzed by creatine kinase (CK)
-Molecular weight of 113 Da – readily filtered by glomerulus.
-Not reabsorbed

Back 89

creatinine

Front 90

-0.6 to 1.2 mg/dL (male)
-0.5 to 1.1 mg/dL (female)

Back 90

reference range for creatinine in serum/plasma

Front 91

plasma concnetrations of creatinine is influenced by what two things?

Back 91

-rate of creatinine turnover
-muscle mass

Front 92

creatinine is freely filtered by the

Back 92

glomerulus

Front 93

-reabsorption if any, is insignificant
-small but insignificant amount is secreted by PCT

Back 93

Creatinine

Front 94

-Positive bias from keto acids, glucose, drugs, protein, uric acid etc.
-Negative bias from bilirubin.
-Sample: plasma, serum or urine
-Measured at 490-500nm at 30C

Back 94

Jaffe method for creatinine measurement

Front 95

elevated plasma creatinine means

Back 95

Abnormal glomerular function= abnormal renal function

Front 96

can plasma creatinine alone be used to assess glomerular function?

Back 96

no.

Front 97

_____ % of renal function must be lost for creatinine to be abnormal

Back 97

50-60 %

Front 98

levels of creatinine are very low in _____ as compared to _____

Back 98

plasma; urine

Front 99

What two things must be used to asses renal function?

Back 99

GFR along with plasma creatinine

Front 100

-measures whether blood is reaching the kidney (mL of plasma passing through the kidney in one minute).
-normal ~ 600 mL/min

Back 100

RPF (Renal plasma flow)

Front 101

-measures whether blood that reaches the kidney is filtered across the glomerulus (rate of protein free fluid formed per minute).
-normal 125 - 130 mL/min

Back 101

GFR (glomerular filtration rate)

Front 102

mL of plasma from which the kidney can remove all of a given substance in one minute

Back 102

Lab measurement of filtration clearance

Front 103

-measure a substance in blood that after being filtered at the glomerulus will remain in the tubules (not reabsorbed, and no more enters the tubule);
-collect all the urine produced during 24 hours;
-measure concentration of solute in the blood and the urine sample
-calculate rate of clearance

Back 103

Lab measurement of filtration clearance

Front 104

most commonly used solute to calculate GFR

Back 104

creatinine

Front 105

overestimated by 10%

Back 105

creatinine clearance

Front 106

97-137 ml/min/1.73m^2

Back 106

creatinine clearance reference range for males

Front 107

88-128 ml/min/1.73^2

Back 107

creatinine clearance reference ranges for females