Chapter notes about Metabolism
Hormonal Regulation of Energy Metabolism
Uptake, Utilization, and Storage of Energy in Carbohydrates
Glucose in blood (Fig. 21.1a)
a.Glucose transported thru out cells by glucose transporters
b. Inside cell glucose oxidized for energy and generates CO2 as waste, converted to
glycogen for storage, and provide substrates for other metabolic rxns
c.If glucose level dec. glycogen can be broken down o glucose by glycogenolysis
Uptake, Utilization, and Storage of Energy in Proteins
Amino acids are transported in blood stream
a.Amino acids used for synthesis of proteins
b. Catabolyzed for energy by proteolysis
c.Proteins broken down to amino acids
d. Amino acids , Catabolized can be used for energy on cells.
Catabolism to generate energy and occurs during starvation and generates C02 and ammonia
converted to urea and release via urine.
Uptake, Utilization, and Storage of Energy in Fats
Lipolysis – broken down of triglycerides to fatty acids and glycerol
a.Triglycerides (fats) transported in bloodstream in Lipoproteins – small protein and lipid
containing particles, transport lipids to various target cells in the body but lipids need to
leave target cells immediately.
b. Triglycerides broken down by lipoprotein lipase – in capillaries running down to adipose
tissue. – breaks down triglycerides into fatty acids taken up by nearby cells and
monoglycerides remain in blood stream and metabolized in liver eventually.
c.On entering cells, fatty acids oxidized for energy or combined w/triglycerol to form new
triglycerides stored in fat droplets in cytosol
d. Storage occurs mainly in adipocytes – adipose tissue cells specialized for fat storage.
e.Stored triglycerides broken down to glycerol and fatty acids w/c can be catabolized for
energy and released to cells.
f. Catabolism for glycerol and fatty acids produce C02 as waste
Energy Metabolism During Absorptive and Post absorptive States
Absorptive state - period following a meal during which nutrients are absorbed
Energy input exceeds energy output
Postabsorptive state - period between meals during whichh stored nutrients are mobilized to
provide energy for cells
Energy expenditure > rate of energy intake
The Pancreas (6.10 a)
a gland located in the abdominal cavity that performs endocrine and exocrine functions;
secretes pancreatic juice and hormones, including insulin and glucagon
Islets of Langerhans – cell clusters in pancreas in spaces between ducts that is the source of 2
major hormones : Insulin – secreted by beta cells and Glucagon – secreted by Alpha cells. Both
are important in regulation of energy metabolism and blood glucose level.