Physiology of Digestion and Absorption Study Guide Flashcards
3 macronutrients that predominate human diet
Carbohydrates, Lipids, Proteins
2 micronutrients
vitamins and minerals (vitamin d and iron for example)
primary and preferred fuel source for the human body
Carbohydrates (specifically glucose)
glycogen
Excess glucose is converted to glycogen or fat and stored in the liver
Small amounts from the glycogen in meat
list of the different types of lipid in the human diet with their functional use
- Adipose tissue for protection, insulation, fuel storage
- Phospholipids for myelin sheaths, cell membranes
- Cholesterol to stabilize membranes; a precursor of bile salts and steroid hormones
- Prostaglandins for smooth muscle contraction, BP control, inflammation
- Absorption of fat-soluble vitamins
- Fuel for hepatocytes and skeletal muscle
proteins
- Structural materials – keratin, collagen, elastin, muscle protein
- Functional molecules – enzymes and hormones
complete proteins
contain all essential AAs
- Animal products – eggs, milk, fish, meats
- Soybeans
Incomplete Proteins
lacking some essential AAs
- Beans, nuts, cereals
After digestion, the chemical subunits of the nutrients we eat are absorbed through what type of epithelial cell?
Enterocytes (simple columnar epithelial) Material must move through the enterocytes – enters via apical membrane, exits through basolateral membrane to interstitial fluid
absorption pathway of carbohydrates
starch and glycogen → oligosaccharides and disaccharides → lactose, maltose, sucrose → glucose, fructose, galactose
absorption pathway of proteins
proteins → large polypeptides → small polypeptides, small peptides → amino acids
absorption pathway of Nucleic acid
nucleic acids → nucleotide monomers → free nitrogenous bases, pentose sugars, phosphate ions
absorption pathway of lipids
triglycerides → monoglycerides + 2 free fatty acids → micelles: FFA?monoglyceride + bile salt → chylomicron: recombined triglycerides → free fatty acids + glycerol
smallest chemical subunits of carbs, lipids, proteins, nucleic acids
Carbohydrate: monosaccharides – glucose, fructose, galactose
Lipids: free fatty acids + glycerol
Protein: amino acids
Nucleic acid: free nitrogenous bases, pentose sugars, phosphate ions
Be able to state what enzyme is primarily driving digestion of each type of nutrient
Carbohydrates: begins with salivary amylase and continues with pancreatic amylase
Proteins: digestions begins when pepsinogen is converted to pepsin (dependent on acidic pH), and then continues by pancreatic proteases
Lipids: digestion begins with emulsification and continues with lingual, gastric, pancreatic lipases
Micelles
FFA/monoglycerides + bile salt
part of lipid digestion
chylomicrons
recombined triglycerides
part of lipid digestion
What solute is primary responsible for creating and maintaining the concentration gradient needed to drive the reabsorption of water by the LI?
Sodium
Malabsorption
can result from anything that interferes with delivery of bile or pancreatic juice or from anything that damages intestinal mucosa (ex: bacterial infections or antibiotics)
Celiac Disease/Gluten-Sensitive Enteropathy
a common malabsorption disease
- Chronic, genetic condition that causes an immune reaction to gluten
- Gluten is a protein found in many grains
- Intestinal villi and brush borders are damaged
- Affects 1:100 people
- Symptoms: bloating, diarrhea, pain, malnutrition
- Treatment: gluten-free diets
cellular respiration equation
C6H12O6 +6 O2 ——>6 CO2+ 6 H2O
Stage I of metabolism
Digestion, Absorption, Transport to Tissues
stage II of metabolism
Cellular Processing in the Cytoplasm
- Synthesis of lipids, proteins, glycogen
- Catabolism into pyruvic acid and acetyl CoA (glycolysis)
stage III of metabolism
Catabolism in the Mitochondria
- Oxidative breakdown into CO2, H2O, and ATP