LECTURE 10

Question 1

Tubular Secretion

Answer 1

Substances from peritubular capillary (and vasa recta) blood are dumped into renal tubule lumen

Question 2

What controls H secretion in the DCT?

Answer 2

Intercalated A cells: Secrete H and absorbe Bicarbon

Intercalated B cells: Secrete Bicarbon and absorb H

Question 3

What causes variable amounts of H+and K+secreted by the DCT?

Answer 3

High blood H+and K+results in more secretion

High blood K+simulates release of aldosterone
which puts Na/K pumps

Question 4

What is secreted into the lumen of the nephron loop?

Answer 4

Mainly urea in thin descending limb

Question 5

What portions of the nephron and collecting system are primarily responsible for water conservation?

Answer 5

DCT and Collecting system

Question 6

What hormones are responsible to water conservation?

Answer 6

Aldosterone causes sodium to be reabsorbed

ADH causes aquaporins to be placed in apical membranes of cells and water to be reabsorbed

Question 7

What Triggers Aldosterone and ADH?

Answer 7

Low blood volume
low blood pressure
high blood osmolarity

Question 8

What cell allows for water conservation? and how?

Answer 8

Principal cell respond to ADH and install auquaporins so water can move to the area of higher ozmolarity

Question 9

Define Countercurrent Exchange

Answer 9

“Countercurrent” because blood in vasa recta flows in opposite direction of tubular fluid

“Exchange”because vasa recta constantly exchanges water and solutes in both directions so as not to disrupt the concentration gradient

Question 10

Tubular fluid going through the Countercurrent multiplier:

Answer 10

Water is removed from the thin descending limb as the solute concentration increases deeper in the medulla. Na+ K+ Cl- are removed from the thick ascending limb and the solute concentration gradient decreases back towards the cortex.

Question 11

Urea

Answer 11

Urea cycling increases solute concentration in medulla.

Question 12

Which class of nephrons participates in the countercurrent multiplier? Why?

Answer 12

Juxtamedulary nephrons. Their nephrons are surrounded by Vasa recta capillaries that take up and release salt in appropriate amounts to maintain the concentration gradient.

Question 13

What is the purpose of creating and maintaining a medullary solute gradient?

Answer 13

Concentrating your urine.

Question 14

When is there is a need to conserve water?

Answer 14

When plasma volume drops and plasma osmolarity increases.

Question 15

What happens when Aldosterone and ADH are released?

Answer 15

Sodium reabsorbed and aquaporins constructed in DCTs and collecting ducts. Most of the water is then reabsorbed.

Question 16

Compared to blood we can concentrate our urine by a factor of?

Answer 16

4x

1200 mOsm

Question 17

What happens when plasma volume is high?

Answer 17

Do not release ADH, so water not reabsorbed. Aldosterone is still used to reabsorb sodium.

Question 18

Ozmolarity of Dilute urine compared to blood?

Answer 18

6x more dilute

50 mOsm

Question 19

Alcohol

Answer 19

Diuretic
Inhibits ADH
Causes larger volume of dilute urine

Question 20

Caffeine

Answer 20

Diuretic that inhibits reabsorption of sodium.

Also dilates afferent arteriole, increasing GFR.

Question 21

Diabetes Type 1 and 2 mellitus, gestational

Answer 21

-Metabolic disorders resulting in chronic polyuria
–Type 1 and 2 mellitus, gestational
–High concentration of tubular glucose
–Nephrogenic DI is when receptors on principal cells do not respond to ADH, or aquaporin-2 gene is abnormal

Question 22

Diabetes insipidus

Answer 22

–Nephrogenic DI is when receptors on principal cells do not respond to ADH, or aquaporin-2 gene is abnormal

Question 23

Urine average pH

Answer 23

6

Question 24

Urine Specific gravity

Answer 24

1.003-1.030

Question 25

Urine Osmolarity

Answer 25

50-1200

Question 26

Urine Volume

Answer 26

700-2000

Question 27

Urine Color

Answer 27

Clear to Yellow

Question 28

Urine Bacterial content

Answer 28

none

Question 29

higher concentration in blood

Answer 29

AAs Bicarbonate Glucose Lipids

Question 30

Higher concentration in Urine

Answer 30

Creatinine Potassium Urea Uric acid

Question 31

Sodium content in Urine

Answer 31

Variable dependent on diet

Question 32

Glucose

Answer 32

Glucosuria: Diabetes mellitus/gestational

Question 33

Protein

Answer 33

proteinuria: High protein diet, Hypertension, Glommerulorphitis increase in permeability

Question 34

Erythrocytes

Answer 34

Hematuria

Bleeding in urinary tract, trauma, kidney stones, infection, or tumors

Question 35

Leukocytes

Answer 35

pyuria
UTI
Turbidity of urine

Question 36

Renal calculi

Answer 36

Kidney stones:

Calcium, magnesium, or uric acid deposits

Question 37

Structure of openings of Ureters

Answer 37

They are narrow one way calves to prevent back flow

Question 38

Trigone

Answer 38

The area between the Uretral openings and the internal urethral sphincter. smooth epithelium to funnel urine out

Question 39

Micturition Reflex

Answer 39

While bladder is filling, detrusor muscle is relaxed due to sympathetic fibers releasing NE
Different sympathetic fibers cause contraction of internal urethral sphincter (different receptor type)
Somatic control over external urethral sphincter
As bladder fills, stretch receptors in bladder muscle send sensory signals to spine and brain along pelvic nerves
Micturition reflex initiated when bladder has approximately 200ml or more urine

-Micturition center is located in pons
Integration center that communicates with cerebrum and amygdala
-Motor signal from pons travels back to detrusor muscle via parasympathetic fibers
-Causes contraction of muscle and relaxation of internal urethral sphincter
-Somatic motor neurons descend and control the external urethral sphincter
If bladder is full enough, urination will occur once external urethral sphincter is voluntarily relaxed
-Less than 10ml of urine remains in bladder after complete micturition
Incontinence is the inability to voluntarily control micturition