Glycolysis and heart Flashcards
Why are cardiac muscle cells connected by gap junctions?
Since cardiac muscle contraction is triggered by action potential spreading across the muscle cells, the gap junctions allows for the electrical activity to spread rapidly from one cell to the other.
How does the SA node initiates the contractions?
Ions channels in these cells open in a cyclic self-sustaining pattern that alternately depolarizes and re polarizes the plasma membranes of the pacemaker cells of the SA node. The regularly timed depolarization spread to neighboring cells causing them to contract and initiating waves of contraction that travel over the entire heart.
How are glucose and galactose aborbed?
Glucose and galactose go through the apical membrane of the epithelial cells using symport with Na+, use facilitated diffusion to cross the basal membrane and enter fenestrated capillaries.
How is fructose absorbed?
It goes through the apical and basal membrane using facilitated diffusion and enters the fenestrated capillaries.
How are amino acids absorbed?
They cross the apical membrane using co-transport with Na+ ions and use facilitated diffusion or co-transport to enter the fenestrated capillaries.
How are dipeptides and tripeptides absorbed?
They go through the apical membrane using co-transport with H+ ions, they are then transformed into amino acids before exiting the cells using facilitated diffusion to enter the fenestrated capillaries.
How is water absorbed?
OSMOSIS and it goes to the lacteal and blood systems.
What are the tree organs that do not require insulin for the absorption of glucose?
The brain, the liver and the exercising muscle.
What are the two mains sources of glucose?
Our food (carbohydrates) and glycogen, that is the storage form of glucose which is stored in mucles cells and the liver.
What are the five classes of enzymes in glycolysis and ther function?
Kinase: transfer of phosphate and ATP
Mutase: transfer a FG from one carbon to another
Isomerase: changes the conformation of a molecule
Enolase: removes water
dehydrogenase: removes hydrogen
Where does lactic acid fermentation occurs?
In muscle cells during strenuous exercise, by some lactic acid bacteria and by some animals in low O2 environment deep at sea, yeast.
What are the advantages of lactic acid fermentation?
It regenerates NAD+ which allows glycolysis to continue, and provides ATP, but it is not too efficient (2.5M ATP/min) and a lot of energy is lost as heat.
What are the disadvantages of lactic acid fermentation?
it is short-term due to the decrease in pH and it creates and oxygen debt since the lactic acid diffuses out of the cell and is transported back to the liver where it is converted back to pyruvates, then ATP or glucose using ATP from oxidative phosphorylation
What are the two enzymes used in ethanol fermentation? Which one does humans have?
Pyruvate decarboxylase and alcohol dehydrogenase. Humans only have alcohol dehydrogenase in case too much ethanol is consumed. HUMANS NEVER DO ETHANOL FERMENTATION
Where does ethanol fermentation occur?
It occurs in some bacteria, in plants roots if they are flooded, yeast and it is very rare in animals.
