Animal Bio: Digestion

Question 1

What is metabolic rate? What does it depend on?

Answer 1

The rate at which the body converts stored energy into working energy.

BASH:

Body size (more muscle mass = higher metabolism)
Age (younger = lower metabolism)
Sex (males have higher metabolism)
Heredity factors (genetics)

Question 2

Explain the process of chemical protein digestion.

Answer 2

Stomach: Pepsin breaks down long-chain proteins

Pancreas secretes trypsinogen, erepsin, and carboxypeptidase into duodenum.

In duodenum, the enzyme enterokinase converts inactive trypsinogen into active trypsin, breaking down proteins into shorter chains.

Erepsin breaks short-chain proteins into individual amino acids.
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https://www.boundless.com/physiology/textbooks/boundless-anatomy-and-physiology-textbook/digestive-system-23/chemical-digestion-224/chemical-digestion-of-carbohydrates-proteins-lipids-and-nucleic-acids-1104-1171/

Question 3

Explain the process of chemical carbohydrate digestion.

Answer 3

Amylase in saliva breaks down starch and continues to do so through to the stomach.

Amylase secreted by pancreas into duodenum continues to break down poly- and disaccharides into monosaccharides (glucose).

Glucose is absorbed into the blood through small intestine.
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https://www.boundless.com/physiology/textbooks/boundless-anatomy-and-physiology-textbook/digestive-system-23/chemical-digestion-224/chemical-digestion-of-carbohydrates-proteins-lipids-and-nucleic-acids-1104-1171/

Question 4

Explain the process of lipid digestion, both physical and chemical.

Answer 4

The liver secretes bile. This is stored in the gallbladder until fats enter the duodenum, when the hormone CCK is released signaling for the release of bile.

The bile physically breaks down large fat globules into small micelles. This allows for a greater surface area for lipases to act on.

Lipases are secreted by the pancreas into the duodenum, where they chemically break lipid chains down into shorter chains and eventually individual fatty acids.