Flashcards in Lab 12 Deck (55):
Filters the blood.
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
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 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
The kidney produces _____ liters of filtrate from the blood every day. Only _____ liters is excreted from the body daily.
What happens to the rest?
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?
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?
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?
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