Physiology of Digestion and Absorption Study Guide

Question 1

3 macronutrients that predominate human diet

Answer 1

Carbohydrates, Lipids, Proteins

Question 2

2 micronutrients

Answer 2

vitamins and minerals (vitamin d and iron for example)

Question 3

primary and preferred fuel source for the human body

Answer 3

Carbohydrates (specifically glucose)

Question 4

glycogen

Answer 4

Excess glucose is converted to glycogen or fat and stored in the liver
Small amounts from the glycogen in meat

Question 5

list of the different types of lipid in the human diet with their functional use

Answer 5

• 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

Question 6

proteins

Answer 6

• Structural materials – keratin, collagen, elastin, muscle protein
• Functional molecules – enzymes and hormones

Question 7

complete proteins

Answer 7

contain all essential AAs
- Animal products – eggs, milk, fish, meats
- Soybeans

Question 8

Incomplete Proteins

Answer 8

lacking some essential AAs
- Beans, nuts, cereals

Question 9

After digestion, the chemical subunits of the nutrients we eat are absorbed through what type of epithelial cell?

Answer 9

Enterocytes (simple columnar epithelial) Material must move through the enterocytes – enters via apical membrane, exits through basolateral membrane to interstitial fluid

Question 10

absorption pathway of carbohydrates

Answer 10

starch and glycogen → oligosaccharides and disaccharides → lactose, maltose, sucrose → glucose, fructose, galactose

Question 11

absorption pathway of proteins

Answer 11

proteins → large polypeptides → small polypeptides, small peptides → amino acids

Question 12

absorption pathway of Nucleic acid

Answer 12

nucleic acids → nucleotide monomers → free nitrogenous bases, pentose sugars, phosphate ions

Question 12

absorption pathway of lipids

Answer 12

triglycerides → monoglycerides + 2 free fatty acids → micelles: FFA?monoglyceride + bile salt → chylomicron: recombined triglycerides → free fatty acids + glycerol

Question 13

smallest chemical subunits of carbs, lipids, proteins, nucleic acids

Answer 13

Carbohydrate: monosaccharides – glucose, fructose, galactose
Lipids: free fatty acids + glycerol
Protein: amino acids
Nucleic acid: free nitrogenous bases, pentose sugars, phosphate ions

Question 14

Be able to state what enzyme is primarily driving digestion of each type of nutrient

Answer 14

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

Question 15

Micelles

Answer 15

FFA/monoglycerides + bile salt
part of lipid digestion

Question 16

chylomicrons

Answer 16

recombined triglycerides
part of lipid digestion

Question 17

What solute is primary responsible for creating and maintaining the concentration gradient needed to drive the reabsorption of water by the LI?

Answer 17

Sodium

Question 18

Malabsorption

Answer 18

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)

Question 19

Celiac Disease/Gluten-Sensitive Enteropathy

Answer 19

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

Question 20

cellular respiration equation

Answer 20

C6H12O6 +6 O2 ——>6 CO2+ 6 H2O

Question 21

Stage I of metabolism

Answer 21

Digestion, Absorption, Transport to Tissues

Question 22

stage II of metabolism

Answer 22

Cellular Processing in the Cytoplasm
- Synthesis of lipids, proteins, glycogen
- Catabolism into pyruvic acid and acetyl CoA (glycolysis)

Question 23

stage III of metabolism

Answer 23

Catabolism in the Mitochondria
- Oxidative breakdown into CO2, H2O, and ATP

Question 24

congenital defects associated with digestive tract

Answer 24

Cleft Palate: the palatine bones fail to fuse
Cleft Lip: the upper lip fails to fuse
Esophageal Atresia/Tracheoesophageal Fistula: improper development of the esophagus; an opening between the trachea and esophagus
cystic fibrosis

Question 25

Cystic Fibrosis

Answer 25

impairs the pancreas through production of abnormally thick mucus – blocks the digestive organs’ ducts

Question 26

Rooting Reflex

Answer 26

head turns towards the stroked cheek

Question 27

Sucking Reflex

Answer 27

sucking upon stimulus to the roof of the mouth

Question 28

digestive impairments seen in the elderly population

Answer 28

• GI tract activity declines with age – less digestive juice, less absorption, peristalsis slows – constipation becomes common
• Taste and smell become less acute, eating becomes less appealing
• Diverticulosis, fecal incontinence, and GI tract cancers are fairly common in the elderly
• Stomach and colon cancers have minimal early signs and often metastasize before detection. With early detection, GI tract cancers are typically treatable.