29: Metabolic Pathways Flashcards
metabolism
two parts, anabolism & catabolism
anabolism
the process of forming large molecules from smaller ones.
catabolism
breaking down large molecules into smaller ones
Conversion of glucose and oxygen to carbon dioxide and water involves three processes:
glycolysis, the citric acid cycle, and the electron transport system.
Glycolysis
occurs in the cytoplasm of the cell and does not require oxygen, 2
lactic acid
If there is not sufficient oxygen, pyruvic acid is converted to lactic acid that accumulates in the tissues causing a local acidosis.
aerobic
With oxygen, the pyruvic acid continues on to enter the mitochondria where oxygen-requiring (aerobic) processes are responsible for most of the ATP produced from the metabolism of glucose
citric acid cycle
The citric acid cycle occurs in the mitochondria. Oxygen is not used in the cycle, but if the last phase (the electron transport system) is stopped for lack of oxygen, the products of the citric acid cycle accumulate and the cycle stops, 2
electron transport system
consists of a series of electron carrier enzymes located on the inner mitochondrial membranes. 34
glycogen
Excess glucose can be stored as glycogen in muscle and the liver, or it can be converted to fat and stored in the liver or in adipose tissue
acids, glycerol,
If insufficient glucose is available, fatty acids, glycerol, and deaminated (nitrogen removed) amino acids can enter the pathways described above to produce ATP
Lipid molecules
include the triglycerides, phospholipids and cholesterol.
urea
The nitrogen is converted to urea and excreted in the urine
hypothalamus
Consistent with the principle that control of functions vital to life originate from lower brain centers, control of feeding is centered in the
leptin,
A chemical mediator called leptin, released from fat cells, is involved. Leptin produced in proportion to fat reserves acts to suppress appetite
