Chapter 6 The Proteins and Amino Acids Flashcards
How is protein digested and absorbed?
- Begins in the stomach where HCl denatures the protein in food and other enzymes attack the peptide bonds
- Further broken down and absorbed in the small intestine
- Dipeptides and tripeptides are broken down into single amino acids on the surface on intestinal cells and absorbed
- Proteins enter the bloodstream and get sent to the liver
- Liver processes them and sends them out to the body
What is the fate of amino acids and proteins in the body?
for cellular use we build protein, a needed compound, and dismantling amino acids for component parts
wasting of amino acids
What four conditions satisfy the wasting of amino acids?
- Body lacks energy from other sources
- The diet supplies more protein than the body needs
- Too much of a single amino acid
- Diet = low quality protein
What is the role of amino acids and proteins in the body?
- regulation of gene expression
- providing structure and movement through muscle tissue (40% of body protein exist here) and other structural proteins (confer shape and strength to bones, teeth, skin, tendons, cartilage, blood vessels)
- building enzymes, hormones, and other compounds
- building antibodies used to destroy one specific invader
- transporting substances like hemoglobin and lipoproteins
- maintaining fluid and electrolyte balance through buffers preventing acidosis and alkalosis
- blood clotting
- providing energy and glucose under conditions of inadequate carbs
*Each day, a quarter of the body’s amino acids are “irretrievably used”
How is protein stored?
- no storage compound for protein
- excess amino acids have amine groups removed and remaining residues converted to glucose and used to either meet immediate energy needs or be stored as glycogen
*note that stripped amine group (nitrogen) is incorporated into urea by the liver and sent to the kidney for excretion
Are protein supplements effective?
Not really. They don’t improve performance, aren’t effective for weight loss and most of the time are not necessary since we meet our protein needs
keep in mind that Fat-free Greek yogurt offers just as much protein as protein shakes
How much protein does an average adult need a day?athlete?how is requirement determined?
Average: 0.8 g/kg/day
Athletic: 1.2-1.7 g/kg/day
Requirement does depend on the body’s health
what are some conditions that happen to the body that require an increased need for protein?
Cachexia and trauma (due to illness or burns) are states in which the body has an increased need for protein
rank proteins sources by digestibility?
Protein from animal sources = ~90% digestible
Legumes ~80% digestible
grains/other plant sources = ~70-90% digestible
What is nitrogen balance?
Nitrogen balance is the ratio of nitrogen excreted compared to nitrogen consumed
what is nitrogen equilibrium?
Equilibrium: Nin = Nout
e.g. – Normal, healthy people
what is negative nitrogen balance?
Negative: Nin < Nout
Here, muscle and other protein tissues are broken down or lost to make up remainder
e.g. – Astronauts or severely ill individuals
what is positive nitrogen balance?
Positive: Nin > Nout
e.g. – Children, pregnant women, weight lifters, etc.
what are the different forms/types protein can take?
Globular – They’re…globular…and water soluble
ex. Proteins of the blood
Hollow – Carry and store materials
Long, rod-like structures – Insoluble in water and very strong
ex. Tendons
what are the disorders associated with protein deficiency?
Kwashiorkor (often seen in children)
Impacts stature, lean body mass, and fluid balance
what are the disorders associated with energy deficiency?
marasmus
