renal function

Question 1

What is the function of the renal system?

Answer 1

• excretion of waste products & urine
• regulation of BP
• RBC production (erythropoietin)
• breakdown of drugs
• metabolism of hormones
• regulation of electrolytes & acid-base balance
• synthesis of vitamin D
• fluid balance
• balance pH of blood stream

Question 2

What is inactivates when kidneys are not functioning properly and why is this a problem?

Answer 2

vitamin D is inactivated; vitamin D plays a role with calcium absorption

Question 3

How many lobes are in each kidney?

Answer 3

8 - 18 lobes

Question 4

Where are the kidneys located?

Answer 4

located retroperitoneally on the posterior wall of the abdomen

Question 5

What is each lobe of the kidneys composed of?

Answer 5

nephrons; functional unit of the kidney

Question 6

What does the renal cortex contain?

Answer 6

contains glomeruli, convoluted tubules, & blood vessels

Question 7

Which kidney is slightly lower than the other and why?

Answer 7

right kidney is slightly lower than the left; because of the liver

Question 8

Where are the renal pyramids in the kidneys?

Answer 8

in the inner medulla

Question 9

What shape are the kidneys?

Answer 9

bean shaped

Question 10

Why is it hard for the kidneys to get injured?

Answer 10

they are semi protected by the ribs and other organs

Question 11

What is the renal pelvis?

Answer 11

the collection system of the urine

Question 12

the kidneys take how much of the body’s cardiac output?

Answer 12

20-25%

Question 13

What does the renal artery divide into?

Answer 13

divides into 5 segmental arteries that enter the hilus

Question 14

What do the segmental arteries branch into?

Answer 14

segmental arteries inside the kidney branch into lobular arteries then interlobular arteries

Question 15

How much blood do the kidneys filter?

Answer 15

kidneys filter about 90-120ml of blood per minute

Question 16

What do nephrons lack the ability to do?

Answer 16

regnerate; causes generalized decrease in functioning nephrons as we age

Question 17

What do glomerulus work in?

Answer 17

filteration

Question 18

What do peritubular capillaries work in?

Answer 18

reabsoprtion

Question 19

List structures of the nephron (hint:4)

Answer 19

proximal convoluted tubule
loop of henle
distal convoluted tubule
collecting duct

Question 20

What are the two categories of nephrons?

Answer 20

1. cortical
2. juxtamedullary

Question 21

What nephrons are thin and penetrate the entire length of the medulla?

Answer 21

juxtamedullary nephrons

Question 22

What nephrons are the primary site of urine concentration?

Answer 22

juxtamedullary nephrons

Question 23

What percent of nephrons are cortical nephrons?

Answer 23

85%

Question 24

What kind of nephrons have short, thick loops of henle that penetrate only a short distance into the medulla?

Answer 24

cortical nephrons

Question 25

If you lose/ donate a kidney why are you able to live without that one kidney?

Answer 25

you are able to live because the other one will compensate for the missing one

Question 26

what are capillaries enclosed in thin, double-walled capsules (bowman capsule)?

Answer 26

glomerulus capillaries

Question 27

how does blood circulate through the glomerulus capilaries?

Answer 27

goes from the afferent arteriole → glomerular capillaries → efferent arteriole → peritubular capillaries

Question 28

What are the three layers of the glomerular capillary membrane?

Answer 28

1. capillary endothelial layer 2. basement membrane 3. single-celled capsular epithelial layer

Question 29

What is the average glomerular filtration rate?

Answer 29

125 ml/min or 180L/day

Question 30

What is filtration pressure & GFR regulated by?

Answer 30

constriction/ relaxation of the afferent & efferent arterioles - arterioles innervated by SNS - arterioles sensitive vasoactive hormones

Question 31

When does renal function begin to decline?

Answer 31

around age 40

Question 32

there is approximately a ____ loss of nephrons for each decade after 40

Answer 32

10%

Question 33

By age 70 what is the average GFR?

Answer 33

down 30ml/ min; 95ml/min

Question 34

If an individual is healthy decline in nephrons will have little impact until what age?

Answer 34

90

Question 35

What will the GFR be in ESRD?

Answer 35

15ml/min or less

Question 36

What indicates good renal function?

Answer 36

a high GFR; the higher the GFR the better

Question 37

How does increased protein and glucose load effect the kidneys?

Answer 37

can cause renal damage

Question 38

What are the two mechanisms that regulate renal blood flow?

Answer 38

- neural & humoral control mechanism - autoregulatory mechanism

Question 39

What happens in the naural & humoral control mechanism?

Answer 39

increase in SNS activity → constriction of arterioles → decrease in renal blood flow

Question 40

What are the humoral substances released in the neural & humoral control mechanism?

Answer 40

- angiotensin II - endothelin - endothelial-derived nitric oxide

Question 41

What do prostaglandins do in the neural & humoral control mechanism?

Answer 41

protect against vasoconstriction effects of sympathetic stimulation & angiotensin II

Question 42

What humoral substance preferentially constricts efferent arterioles?

Answer 42

angiotensin II

Question 43

What is endothelin and what does it act like in the neural & humoral control mechanism?

Answer 43

peptides released from damaged endothelial cells in the kidney & other tissues; vasoconstrictor

Question 44

What class of medications inhibit prostagladin?

Answer 44

NSAIDS

Question 45

Why should NSAIDS be avoided?

Answer 45

they inhibit prostaglandin synthesis; decrease renal blood flow & decrease the GFR

Question 46

in what mechanism is the exact mechanism responsible for renal blood flow regulation unclear?

Answer 46

autoregulatory mechanism

Question 47

What occurs in the proposed autoregulatory mechanism 1?

Answer 47

- direct effect on vascular smooth muscle - increase in BP causes vessels to relax - decrease in BP causes vessels to constrict

Question 48

What is the second proposed autoregulatory mechanism?

Answer 48

juxtaglumerular complex; feedback control system that links RBF to GFR and composition of distal tubular fluid

Question 49

What are macula densa cells?

Answer 49

specialized group of epithelial cells in distal tubule in close contact with afferent & efferent arterioles

Question 50

How do macula densa cells work?

Answer 50

- monitor BP by sensing the stretch of the afferent arteriole (changes in volume delivery) - monitors sodium concentration in filtrate as it flows through

Question 51

What do juxtaglomerular cells contain?

Answer 51

granules of inactive renin

Question 52

What is used to determine renin release?

Answer 52

information from macula densa cells

Question 53

What happens when there is decreased renal perfusion?

Answer 53

RAAS will be triggered

Question 54

where do about 65% of reabsorption & secretory processes occur?

Answer 54

proximal tubule

Question 55

the _________ tubule is highly permeable to water

Answer 55

proximal

Question 56

osmolality _________ and is maximum at the ______ _______ in the loop of henle

Answer 56

increases; loop elbow

Question 57

What portion of the loop of henle is impermeable to water?

Answer 57

ascending loop

Question 58

in the loop of henle, as filtrate ascends it becomes what?

Answer 58

more dilute

Question 59

the distal convoluted tubule is ___________ ___________ to water

Answer 59

relatively impermeable

Question 60

Where do thiazide diuretics work and how?

Answer 60

thiazide diuretics work at the distal convoluted tubule; by inhibiting NaCl reabsorption in this segment

Question 61

Where do potassium sparing diuretics work?

Answer 61

late distal tubule

Question 62

What 3 factors effect urine concentration?

Answer 62

- osmolarity of the interstitial fluids in the urine- concentrating part of the kidney - antidiuretic hormone (ADH) - action of ADH on the cells in the collecting tubules of the kidney

Question 63

list the elimination functions of the kidneys

Answer 63

removal of - water - waste products - excess electrolytes - unwanted substances

Question 64

list the endocrine functions of the kidneys

Answer 64

- assist with BP regulation through renin-angiotensin- aldosterone mechanism - regulation of RBCs through synthesis of erythropoietin - assist with calcium homeostasis by activating vitamin D - glucose homeostasis

Question 65

What do all age related changes in the GU system impact?

Answer 65

all impact the elimination of medications

Question 66

list age-related changes to the GU system

Answer 66

- decrease blood flow to kidneys - decreased number of functioning nephrons - decreased GFR (most reliable indicator) - decrease tubular secretion

Question 67

Why is GFR a better indicator than BUN/Cr?

Answer 67

because it tells us about kidney function & the kidneys ability to excrete waste