Module 5.9: Tubular Secretion Flashcards
What is tubular secretion?
the process of moving solutes from the peritubular capillaries into the tubules
Through the mechanism of tubular secretion, solutes that did not cross the _______ during __________ can be removed from the blood and excreted.
Through the mechanism of tubular secretion, solutes that did not cross the glomerular membrane during glomerular filtration can be removed from the blood and excreted.
The barriers for secretion are the same as the barriers for ______\_ and include
- the ______________,
- the _______,
- the _______ _______, and
- the _______ __________.
The barriers for secretion are the same as the barriers for reabsorption and include
- the capillary endothelial cell,
- the peritubular space,
- the basement membrane, and
- the tubular epithelial cell.
Tubular secretion is important for many molecules, including _______\_, organic __\_ and __\_, and ______\_
Tubular secretion is important for many molecules, including hydrogen ions (H+), organic anions and cations, and potassium (K+)
H+ is secreted via various _________\_in the _________\_, _________\_, and _________\_.
The secretion of H+ and the regulation of that secretion are important for _________\_ balance and will be further discussed in Module 6.
H+ is secreted via various transport proteins in the proximal tubule, distal tubule, and collecting ducts.
The secretion of H+ and the regulation of that secretion are important for acid-base balance and will be further discussed in Module 6.
Organic anions and cations include numerous waste products such as _____\_, _____\_, and foreign compounds, such as _____\_, _____\_, and ______ ______ _____\_ (NSAIDs).
These ions are permeants for families of ______ ______-_____\_or ______ ______-_____\_ transport proteins.
Thus, through the combination of ______ _____\_and ______ _____\_, most of these waste products can be excreted.
Organic anions and cations include numerous waste products such as histamine, norepinephrine, and foreign compounds, such as pesticides, penicillin, and nonsteroidal anti-inflammatory drugs (NSAIDs).
These ions are permeants for families of organic anion-selective or organic cation-selective transport proteins.
Thus, through the combination of glomerular filtration and tubular secretion, most of these waste products can be excreted.
The homeostatic maintenance of K+, like the homeostatic maintenance of Na+, is critical for the functioning of _______\_.
The homeostatic maintenance of K+, like the homeostatic maintenance of Na+, is critical for the functioning of excitable cells.
Define hyperkalemia
A high plasma concentration of K+
Define hypokalemia
low plasma concentration of K+
What is the result of hyperkylemia?
Hypokalemia?
Both hyper and hypokalemia result in Cardiac arrhythmia
In the nephron, where is K+ reabsorbed?
Proximal Tubules
What are two ways K+ is reabsorbed in the proximal tubules?
- moving through the tight junctions linking the tubular epithelial cells and
- by moving through K+ channels located in the basolateral membrane.
What is important about basolateral K+ channels?
Basolateral K+ channels allow K+ that has been pumped into the cell by Na+/K+-ATPases to be reabsorbed.
Potassium (K+) reabsorption in the proximal tubule:
Potassium (K+) is reabsorbed across the _______\_by moving through _______\_ linking the tubular epithelial cells.
Additionally, potassium (K+) moves across the ________ _______\_into tubule epithelial cells by the ________ ________ ________ ________ _______\_ and out of tubule epithelial cells through ________ ________ _______\_.
Potassium (K+) reabsorption in the proximal tubule:
Potassium (K+) is reabsorbed across the proximal tubule by moving through tight junctions linking the tubular epithelial cells.
Additionally, potassium (K+) moves across the basolateral membrane into tubule epithelial cells by the Na+/K+-ATPase primary active transport protein and out of tubule epithelial cells through basolateral potassium channels.
Where is potassium secreted in the nephron?
K+ is secreted by the principal cells of the distal tubules
How is potassium secretion accomplished?
Na+/K+-ATPases pump K+ into the cell across the basolateral membrane, and then K+ moves down its electrochemical gradient through K+channels located in the apical membrane.
Image:
Potassium (K+) secretion in the distal tubule:
Potassium (K+) is secreted by the _____\_cells of the _____\_.
Potassium moves across the _____\_membrane into _____\_ cells of the________ by the______________ primary active transport protein and moves across the apical membrane through ________channels.
Image:
Potassium (K+) secretion in the distal tubule:
Potassium (K+) is secreted by the principal cells of the distal tubule.
Potassium moves across the basolateral membrane into principal cells of the distal tubule by the Na+/K+-ATPase primary active transport protein and moves across the apical membrane through potassium channels.
Secretion of K+ in the distal tubule is regulated by the hormone _\_
Secretion of K+ in the distal tubule is regulated by the hormone aldosterone
How does aldosterone increase K+ secretion?
Through the insertion of additional K+ channels in the apical membrane and additional Na+/K+-ATPases in the basolateral membrane of the epithelial cells, aldosterone increases K+ secretion.
Explain the image:
Regulation of potassium (K+) secretion by aldosterone:
The hormone ____\_binds to ____\_ receptors in the ____\_cells of the distal tubule or _____ ____\_ to increase insertion of additional ____\_ channels in the apical membrane (A) and additional____________ the basolateral membrane (B).
Explain the image:
Regulation of potassium (K+) secretion by aldosterone:
The hormone aldosterone binds to cytosolic receptors in the principal cells of the distal tubule or collecting ducts to increase insertion of additional potassium channels in the apical membrane (A) and additional Na+/K+-ATPases in the basolateral membrane (B).
In addition to being controlled by regulatory mechanisms that respond to changes in Na+ concentrations, aldosterone secretion is increased in response to increased concentrations of ______\_
In addition to being controlled by regulatory mechanisms that respond to changes in Na+ concentrations, aldosterone secretion is increased in response to increased concentrations of plasma K+
Image:
Regulation of aldosterone secretion:
Aldosterone secretion is stimulated by changes to both the plasma concentrations of _______ and ________.
Image:
Regulation of aldosterone secretion:
Aldosterone secretion is stimulated by changes to both the plasma concentrations of potassium (K+) and sodium (Na+).
