Study Aid for D1: Nutrition
Essential nutrient
Non-essential nutrient
Conditionally essential
Ascorbic Acid
Conditionally essential Amino
acids
Essential fatty acids
Essential amino acids
Lack of essential amino acids
in diet causes
Minerals
Iodine deficiency disorder
vitamins
Water soluble vitamins
Fat soluble vitamins
Malnutrition
Hypothalamus
PYY
Insulin
Leptin
Excess fat and refine carbs in
diet
Diabetes I
Diabetes II
Symptoms of diabetes
starvation
PKU
Vitamin D
Anorexia nervosa
Cholesterol
LDL cholesterol
Saturated fats
Calorimetry
Formula
Food only source. Ex. Some Amino acids, minerals, calcium, vitamins, water,
some fatty acids
Can be made in body. Ex. Glucose, starch.
Produced at some point in life but not others: Vitamin K
Also vitamin C. mutation in GLO gene mutates enzyme L-gulano-y-lactone
oxidase so can’t make this vitamin. Result is scurvy when vitamin C is deficient.
Threonine and arginine
Omega-3 and omega 6
Histidine, leucine, lysine, valine, phenylalanine
Body can’t make proteins because they are the building block of proteins.
Protein deficiency malnutrition
Needed in small amounts, usually ionic, lacking in diet causes deficiency
diseases
Lack of iodine needed for thyroid to make hormone thyroxin that stimulates
metabolic rate
Needed in small amounts, act as cofactors for enzymes, anti-oxidants, and
hormones. Can be fat or water soluble
Constantly loss in urine: vitamin B and C
Constantly stored: Vitamins A, D, E, K
Poor diet, low protein and caloric content in diet or unbalanced. To much fats
and carbs
Appetite control center. Signals us when we are full. Receives following 3
hormones from body
Hormone made by small intestines when food is present.
Secreted by pancreas when blood glucose concentration is high
Secreted by adipose tissue when amounts of stored fat increases
Can lead to diabetes and hypertension
Insulin-secreting cells in pancreas destructed
Decrease responsiveness of insulin secreting cells “burn-out”
Elevated blood glucose, glucose in urine, dehydration, thirst, need to urinate a
lot
Leads to breakdown own muscle to get to energy sources. A.A. taken out and
sent to liver to be made into glucose. Muscle mass loss
Genetic, mutation in gene that codes for enzyme that breaks down
phenylalanine. Recessive disease so need to inherit both alleles, can cause
mental retardation, and reduce growth and retardation. Can be controlled by
diet.
Needed for calcium absorption in intestines. Can be made in skin if exposed to
sunlight. Lack of results in rickets or osteomalacia
Illness with voluntary starvation and loss of body mass. Body weight drops and
muscles deteriorates because body breaks them down for energy. Cardiac
muscle also reduced.
Component of plasma membranes, high levels may increase coronary heart
disease, can be made in liver so diet not only source. Some levels controlled
by genetics.
Low density lipoprotein and is implicated with CHD
More correlation with increased risk of CHD
Used to determine energy content of food substance
Mass of water X specific heat X change in temperature
Study Aid for 6.1 Digestion and Absorption and D2 Digestion
Study diagram:
Table of digestive tract
Organ
Digestive Activities
Mouth
Mechanical digestion: chewing
Chemical digestion: saliva contains amylase and lipase
Stomach
Mechanical digestion: churning
Chemical digestion: protease (pepsin)
Small
intestine
Chemical digestion: amylase, protease, lipase (assisted by bile from liver/gall bladder), nuclease
(all enzymes predominantly from the pancreas)
Nutrient and water absorption
Large
intestine
Water absorption
Table of enzymes
Enzyme
Where found
Breaks down
pH
Amylase Mouth and small intestine
Starch to maltose
Neutral to basic
Maltose
Small intestines
Maltose to glucose Basic
Protease
Stomach and small
intestine
Proteins to amino
acids
Lipase
Mouth and small intestine
Lipids to fatty acids Basic
and glycerol
Nuclease Small intestine
Nucleic acids to
nucleotides
Acidic
Basic
Absorption: small molecules and nutrients pass into blood vessels in small intestines.
Assimilation: products of digestion transported to tissues and used.
Starch broken down by amylase into amylopectin and disaccharide maltose. Maltase is then
needed to break it down further to glucose.
Activity of digestive system controlled by nervous system and hormonal mechanisms. Not always
active. Gastric juices can be started by vagus nerve in brain when food is smelt. Distension in
stomach also signals small intestines to get ready
Mouth


Amylase secreted by salivary glands to start breaking starch down to maltose
Stomach

low pH, gastric juice, protection by mucus against self-destruction
o Parietal cells secrete HCl that causes the pH to be very acidic and
disrupts extracellular matrix of cells (kills bacteria)
o Chief cells secrete pepsin which is inactive form of pepsinogen that
hydrolyzes proteins. Acidic environment convert pepsin into active form
pepsinogen.
o Gastric juice = HCl + pepsin + hormones = secreted by the stomach
(parietal and chief cells)
o Pepsin = protease that works best in acidic environment.
o Goblet cells secrete mucus lining that protect the stomach from the acid
and self-digestion.
production of digestive enzymes, site of digestion
o Chemical digestion: Stomach produces pepsin, which digests proteins
(secreted in an inactive form, gets activated in acidic environment)
o Mechanical digestion: Stomach churns food.

Pancreas




Small
Intestines

production of enzymes that do hydrolysis reactions to break down food
o Pancreas is the major source for all the digestive enzymes.
 Amylase - digests starch.
 Various proteases. (Endopeptidases: ex. Trypsin) breaks down proteins
 Lipase - digests lipids.
 Ribonuclease - digests nucleic acids.
o Pancreas makes HCO3- so it is basic to neutralize the HCl from the stomach
Makes pancreatic juice is secreted into small intestine
o Digestive enzymes of pancreas = exocrine = flows into small intestine via duct.
Structure (gross): tadpole-shaped gland with duct leading to duodenum.
Enzymes made by ribosomes in pancreatic gland cells and excreted by exocytosis
into duct.
Absorption of food molecules and water
o Small intestine is the major place for digestion and absorption.
o Folds, villi, and microvilli increases the surface area for absorption.
o Absorbs digested food into circulation (into capillaries).
o Active transport occurs to absorb against the concentration gradient.
 While cell is actively transporting sodium out of cell on basal side (Secondary
active transport by Na+-K+ pump), sodium moves into cell on apical side
bringing a glucose with it.
o Passive/facilitated diffusion occurs to absorb down the concentration gradient.
 Glucose builds up in cell the special exits on basal side through special
glucose channels facilitated diffusion (then the glucose will go from the
extracellular fluid to blood).

Large
intestine

function and structure of villi: increase surface area for more absorption
o Villi = finger-like protrusions inside small intestine.
o Microvilli = same as villi but on the surface of a single absorptive cell.
o Outer layer of microvilli is made of epithelia cells that allow nutrients to pass
through. Capillaries located below these cells.
o Villi absorb monomers: monosaccharides, amino acids, nitrogenous bases,
glycerol, fatty acids, vitamins, and mineral ions.

production of enzymes, site of digestion
o The small intestine is the major place for digestion and absorption.
o Pancreas is the major source for enzymes. However, the small intestine does
make some of its own enzymes, including protease and amylase.

neutralization of stomach acid
o The pancreas makes bicarbonate ion to neutralize the HCl from the stomach.
o This neutralization facilitates enzymes in the small intestine, which would be
denatured by stomach pH.

structure (anatomic subdivisions)
1. Duodenum.
2. Jejunum.
3. Ileum.

Peristalsis mixes food with enzymes and moves it along
o Circular and longitudinal muscles make up tube. Both are types of smooth
muscles.
o Continuous waves of contraction and relaxation controlled by autonomic
nervous system
o Moves food slowly for maximum digestion and absorption

Anatomic subdivisions (old topic)
1. Cecum: blind pocket containing appendix.
2. Ascending colon
3. Transverse colon
4. Descending colon
5. Sigmoid colon
6. Rectum: stores feces.
absorption of water: The large intestine absorbs any remaining water that is not
absorbed by small intestine.
bacterial flora
o Ferment undigested nutrients, make gas.
o Produce vitamin K (important for clotting).
structure (gross): lobes/pockets along its length due to muscle tone. Unlike small
intestine, the large intestine has no folds or villi.



Rectum
Fatty acids and glycerol diffuse into epithelial cells from lumen. They
combine together to form lipoproteins
(storage and elimination of waste, feces)
 Rectum stores feces.
 The anal sphincter ties the end of the rectum.
 During defecation, sphincter opens, feces are released through the anus
Anus
Egested material consists of undigested parts of food and unabsorbed material
o Fiber: parts of plants that are not digested because they contain cellulose. We
don’t have enzymes to breakdown cellulose into small parts so it cannot be
absorbed. It is egested
o If to much water is absorbed could result in constipation. To little food absorbed
results in runny stool
Rate of transit of materials is correlated with fiber
o Fiber helps move food through tube and reduces chances of some illnesses such
as bowel cancer and hemorrhoids.
On picture below label:
the lumen on all
epithelium cell (big one)
apical surface on epithelium
basal surface on epithelium
blood vessel on epithelium
circular and longitudinal muscle
tight junction on epithelial