Ch. 32 Structure and Function of the Kidney

Question 1

Structure of a nephron

Answer 1

each nephron has a glomerulus that filters the blood and a system of tubulur structures.

• Nephron tubule: proximal convoluted tubule, loop of henle, distal convoluted tubule, collecting tubule
• Reabsorbs water, electrolytes and other substances needed to maintain the constancy of the internal environment into the bloodstream.
• Secrete other unneeded material into the tubular filtrate for elimination

Question 2

Structure of the glomerulus

Answer 2

 Whole function is the filtration of blood.
 3 layers: capillary endothelial layer, basement membrane, single celled capsular epithelial layer.
 Urine is made here. No plasma proteins (albumin) go from the afferent arteriole to the proximal convoluted tubule.
 No meds can be filtered that bind to plasma proteins

Question 3

Nephron Tubule

Answer 3

o Proximal convoluted tubule: a highly coiled segment, drains into the bowmans capsule
o Loop of henle: a thin looped structure
o Distal convoluted tubule: a distal coiled portion
o Collecting tubule: joins with several tubules to collect the filtrate

Question 4

Tubular Filtration

Answer 4

o The urine filtrate flows through the tubular component of the nephron. As the filtrate flows through tubule.
o As the filtrate flows through the tubule, the concentration of water and electrolytes in the filtrate changes due to:
 reabsorption of water and solutes by tubular cells into the peritubular capillary blood
 Secretion from the blood into the tubular lumen
o Water and electrolyte management.

Question 5

GFR

Answer 5

This rate can vary from a few milliliters per minute to as high as 200 mL/minute. The average adult has a GFR of 125 mL/minute or 180 L/day.

Question 6

ADH Regulation of Urine Concentration

Answer 6

regulates the ability of the kidney to concentrate urine.

• Controls the permeability of the tubules. Marked water permeability

Question 7

Aldosterone Regulation of Urine Concentration

Answer 7

: the most effect on sodium reabsorption. Water follows sodium.
When there is a reabsorption of sodium, there is a loss of potassium

Question 8

Osmolality control of Urine

Answer 8

 When the amount of water or increase solubility
 Serum osmolality is the amount of water in the intravascular compartment compared to the amount of solutes in the intravascular compartment.
 The more solute, the less water, as the plasma osmolality goes up, there is less water. They work inversely. Increase in osmolality, release ADH

Question 9

Juxtaglomerular Complex

Answer 9

 Thought to represent a feedback control system that links changes in the GFR with renal blood flow.
 Because of its location between the afferent and efferent arterioles, the complex is thought to play a essential feedback role in linking the level of arterial blood pressure and renal blood flow to the GFR and the composition of the distal tubular fluid
 Macula densa: holds renin.
 Any decrease in renal perfusion here leads to renin production

Question 10

Angiotensin 2 Regulation

Answer 10

o Arteriolar vasoconstriction increase in blood pressure
o Tubular sodium chloride reabsorption and K excretion and water retention
o Stimulates adrenal gland to secrete aldosterone
o Pituitary gland secretes ADH which leads to collecting ducts water reabsorption. Decreases plasma osmolality.
o Sympathetic activity: only happens with major blood loss and significant dehydration. Decreased renal blood flow.

Question 11

Erythropoietin

Answer 11

regulates the differentiation of RBCs in the bone marrow

Question 12

Vitamin D

Answer 12

Increases calcium absorption from the GI tract, helps regulate Ca deposition in bone, both have to go through the liver to receive first activation, then to the kidneys to become the true active form of vitamin D

Question 13

Renal Clearance

Answer 13

GFR: how much goes through that capillary and is dumped into bowmans capsule and becomes urine. can use GFR , can look at drugs, proteins, how much is cleared through each pass of the kidney

Question 14

Regulation of Sodium

Answer 14

regulated by the GFR and humoral agents that control their reabsorption. aldosterone functions in the regulation of elimination, withthis, almost all sodium is reabsorbed and the urine essentially becomes sodium free

Question 15

K elimination

Answer 15

travels opposite to Na, aldosterone regulation

Question 16

Uric acid elimination

Answer 16

a product of purine metabolism. Excessively high blood levels can cause gout, and high levels of uric acid in the urine can cause kidney stones. Glomerular filtration.

Question 17

Urea elimination

Answer 17

urea is only out through the kidneys. By product of liver from protein metabolism. High protein diet. Excessive tissue breakdown. Intestinal bleeding. Ammonia > urea
-testing this shows renal function

Question 18

Drug elimination

Answer 18

NSAIDS, aspirin - kidneys, tylenol- liver

Question 19

Tests of Renal Function

Answer 19

Urinalysis, BUN, creatinine, cystoscopy, ultrasound, CT

Question 20

Characteristics of normal urine

Answer 20

Clear, amber colored and sterile
95% water and 5% dissolved liquids
1.5L of urine per day
Contains metabolic wastes and few or no plasma proteins, blood cells, or glucose molecules
Specific Gravity:Varies with its concentration of solutes.
Kidneys produce: 1.030 to 1.040
Range: 1.010 to 1.025
Renal dysfunction: 1.006 to 1.010.9
During marked periods of hydration, can approach 1.000
Can never be exactly 1.000 because that is water.

Question 21

Serum Creatinine

Answer 21

o Estimating the functional capacity of the kidneys. A rise up to 3 times the normal level there is a 75% loss of renal function
o Values of 10 mg/dL or more it can be assumed that approx. 90% of renal function has been lost.
o Filtrated through the glomeruli. Can be tracked.

Question 22

Microscopic Exam of Urine

Answer 22

WBC, RBC, crystals, bacteria, renal casts (mold of distal nephron lumen, when protein is high signifies kidney disease)