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Flashcards in Lab 12 Deck (55):

Filters the blood.

The kidneys


urine is?

Nothing more than substances from the blood plasma that have been filtered out


The kidney works to maintain?

Total blood volume & blood pressure, water, electrolyte concentration, and the pH of the blood.


What is urea?

By-product of protein metabolism


What do the kidneys remove?

nitrogenous waste products, such as urea (by-product of protein metabolism) and uric acid (by-product of nucleic acid metabolism) from the blood.


Besides removing substances, the kidneys also serves to monitor?

oxygen content of the blood. When O2 is low, the kidney secretes erythropoietin, a hormone that stimulates red
blood cell production in the bone marrow.


1) The top for the nephron is within the?
2) And the tubule loop dips down into the?
3) This arrangement is essential for the?

1) cortex of the kidney
2) medulla.
3) formation of urine.


What does the nephron do?

Performs the three major functions of the kidney including filtration, reabsorption, and secretion


What is filtration?

Bulk movement of fluid from the blood into the nephron


What is reabsorption?

Returning substances from the filtrate back to the blood


What is secretion?

Movement of individual ions (H+, K+) from the blood into the nephron tubule


Process of substances moving out of the blood and into the nephron



Where does filtration take place?

At the glomerulus


The innermost layer of the glomerulus is made up of?

The fenestrations of the capillary endothelium.


The fenestrations of the glomeruluer filtration are what?

Pores, are very small, thereby limiting what can pass through based on size


The glomerulur filter has 3 layers



The middle layer of the filter is the?

Basal lamina, which limits what can pass based on the electric charge because this layer has a negative charge, molecules in the blood with a negative charge (e.g., proteins) are repelled by this layer & prevented from passing through this layer


The third and outermost layer of the filter forms the?

Pedicels of the podocytes, which create filtration slits that limit what can pass through based on size


The fluid that leaves the blood in the glomerulus and enters Bowman's capsule is called?



What does the filtrate contain?

Water, ions (electrolytes), organic molecules, and gases-everything you would find in the blood plasma-except proteins which are usually too large to pass


As fluid leaves the glomerulus, it initially collects in the?

Bowman's capsule


Bowman's capsule serves as a?

Funnel that directs the filtrate into the first segment of the nephron tubule called the proximal convoluted tubule, or just the proximal tubule


Reabsorption begins here in the nephron and takes place in every segment from here on in the nephron

Proximal tubule


The kidney produces _____ liters of filtrate from the blood every day. Only _____ liters is excreted from the body daily.
What happens to the rest?

180 liters
Only 1-‐2 liters
A minimum of 400 ml/day must be excreted to remove waste products from metabolism. This is called the obligatory water loss.


Most reabsorption takes place in the? Approximately how much of the filtrate is returned to the blood in this segment of the nephron?

Proximal tubule


What is reabsorbed in the proximal tubule?

Water, ions, gases, and all organic molecules. This is the only location in the tubule where organic molecules can be reabsorbed


What happens if organic molecules are filtered out and are not reabsorbed in the proximal tubule?

They will end up in the urine


When the remaining filtrate leaves the proximal tubule, it moves into the?

descending limb of the loop of Henle


Only water is reabsorbed in this segment of the nephron

Descending limb of the loop of Henle


As the filtrate moves up the ascending limb of the loop, what is absorbed?

Electrolytes (ions) are reabsorbed but not water


What is reabsorbed in the distal convoluted tubule and the collecting duct?

Water and ions


What segments of the nephron are influenced by hormones?

Both the distal convoluted tubule and collecting duct but the collecting duct is most critical. This is the last segment in which water & ions can be reabsorbed.


This is where, if needed the urine is concentrated & water is conserved to prevent dehydration

The collecting duct


If body water levels are elevated what will decrease in the collecting duct?

There will be a decrease in water reabsorption in the collecting duct. This will allow the water to be excreted in the urine.


What else (besides reabsorption if needed) takes place in the collecting duct?

The fine-tuning of ions, including potassium & hydrogen ions


What happens when the concentration of ions is too high?

They will be secreted from the blood into the filtrate to rid the body of them. This secretion is important.


What is hyperkalemia?

When potassium levels in the body are above the normal range


What is hypokalemia?

When potassium levels in the body are below the normal range


What is the importance of keeping the concentration of ions within the normal range? Give high levels of potassium as an example

When potassium levels in the body are above the normal range the resting membrane potentials of body cells can be affected. It would make it much easier for cells to generate action potentials.


The 3 hormones directly related to water & ion balance are?

a) vasopressin
b) aldosterone
c) atrial natriuretic hormone


The 3 hormones related to water & ion balance; vasopressin, aldosterone, & atrial natriuretic hormone do what?

They play the role of efferent pathway, targeting cells of the collecting duct and other related cells


What does vasopressin do?

Vasopressin (a.k.a. Antidiuretic Hormone) increases water reabsorption


What does aldosterone do?

1) Increases sodium reabsorption
2) Increases potassium secretion


What does atrial natriuretic hormone do?

1) Antagonist to other two (vasopressin & aldosterone)
2) Reduces water and salt reabsorption
3) Increases water excretion


What is urinalysis? And what is it used for?

The evaluation of the content of urine. Used in the clinical setting as a standard test for evaluating health


How is a urinalysis used (not what is it used for)

Substances that should be in the urine are tested to determine if they fall within normal levels. Substances that should not be in the urine but show up during a urinalysis can be used to alert a clinician to various conditions or diseases ranging from pregnancy complications to heart attack


The tests conducted to evaluate the urine content include.

1) Visual examination (color, clarity)
2) Reagent test strip (glucose, proteins, ketones, pH, blood (erythrocytes), leukocytes, bilirubin, specific gravity)
3) Microscopic Analysis (blood cells, crystals, casts, bacteria, parasites)


Urine tests of color & clarity can be used as a?

Rough test of content


Urine is normally what color and why?

Yellow because of a byproduct of the breakdown of bilirubin, which is due to the breakdown of red blood cells


If urine color appears reddish what might that indicate?

There may be blood or myoglobin present


If urine appears cloudy there may be?

An infection


The dip-sticks or chemical reagent test strips provide?

A quick test for substances that should not be present in the urine (i.e., glucose, protein, blood cells), the specific gravity (density) and the pH of the urine


The microscopic analysis provides a?

Visual examination of the actual content of the urine


For the microscopic analysis what must happen first?

The urine must first be spun in a centrifuge to separate the liquid from the solid substances. The heavier substances (e.g., cells) will become the sediment on the bottom of the test tube, while the liquid, called supernatant remains above


During the microscopic analysis after the urine is spun, the supernatant (liquid) can be used to test what?

The specific gravity of the urine. But it must be carefully poured off to be able to collect the sediment for analysis. This sediment is inspected & a count is made of the blood & other cells, bacteria, casts, and crystals