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Nutrients are classified as A, B or C nutritional elements.
A: include proteins, fats, and complex carbs
B: iron, calcium
C: vitamins, elements
require digestion prior to absorption
can be absorbed directly; substantial daily need
Dietary protein in humans derives chiefly from animal and vegetable sources whose genomes differ significantly from that of the human. For humans to synthesize their own species-specific proteins, dietary molecules are reutilized.
...enzyme proteins under direction of the human genetic code.
21; 8; de novo
The eight are termed the "essential amino acids".
We can't construct these amino acids as our genetic code does not include messages for the synthesis of the requisite enzyme proteins to establish the proper chemical bonds.
nonessential amino acids
The relative amount of essential to nonessential amino acids, both in general and in respect to specific ones, varies widely with each dietary source; some proteins do not contain any of a given essential amino acid.
Nitrogen liberated from dietary protein is in the form of ammonia, a very potent neurotoxin. Since each amino acid comprising the protein we eat contains a minimum of one amino group (-NH2), the potential for ammonia toxicity increases.
1: Most dietary protein is reutilized as intact amino acids, with the amino group acting as a sort of metabolic "lock" which prevents utilization for energy.
2: The detoxification process in the liver converts liberated ammonia into bio inert urea.
What is the point/function of the "urea cycle"?
This is because these compounds are the sole source of nitrogen.
fructose, glucose, and galactose
lactose (glucose + galactose)
Ingested polysaccharides are usually starch and cellulose, both of which are large glucose polymers.
1: Primary source of energy to offset the use of amino acids.
2: Supplies carbon skeletons for synthesis of nonessential amino acids.
3: Serve as intrinsic components of many complex molecules called glycoproteins and glycolipids.
...12-18 carbon atoms and terminating in a carboxyl group.
There are, of course, similar molecules that are either longer or shorter and are made up of odd as well as even numbers of carbon atoms.
Humans are able to synthesize saturated fatty acids starting from the common 2-carbon biochemical intermediate, acetyl-coenzyme A; unlike the situation with nitrogen, the human body evolved enzymes capable of fixing carbon dioxide.
...alcohol group, to create triglycerides. These mono-, di-, or triglycerides are simply 1, 2, or 3 fatty acids linked to glycerol through ester bonding, created by an enzymatically-mediated reaction btwn alcohol and carboxyl groups.
cholesterol (also a molecule from which many steroid hormoles and compounds related to blood coagulation are derived). It is also an important component of all cell membranes.
...an already elevated blood cholesterol level in prevention or treatment of coronary artery disease.
Moreover, the caloric, or energy value of fat is more than twice that of carbohydrate and protein; thus, reduction of fat may produce a diet too low in calories to meet daily energy requirements.
All vitamins undergo intracellular changes ("activation") which render them __________, in which form they interact w specific enzyme proteins to...
...participate in the production of "transition states" of reactions.
In their native form, as ingested, vitamins are not active have no biological value per se.
Many vitamins are recycled by the body as well; both of these phenomena account for the very small daily quantities required by humans.
However, this distinction does explain various aspects of secondary vitamin deficiencies.
A (Retinol)-------visual pigments----------------night blindness
D (Calciferol)----absorb calcium, build bones---rickets
E (Tocopherol)-protects blood cells-------------anemia
K-----------------------synthesis of prothrombin----excessive bleeding
Ascorbic acid (C)
It is also a cofactor for many critical reactions, incl. those moderated by dehydrogenases. Participates in pyruvate dehydrogenase reaction, which is a pivotal step in energy production. It is widely distributed in the human diet.
Cofactors of riboflavin, flavin mononucleutide or flavin adenine dinucleotide are facile and reversible oxidation-reduction agents, and therefore predictably involved in many key mitochondrial reactions. Deficiency not well-defined.
Comprises a pyridine nucleus which is substitued in one of three ways:
In plant foods as pyridoxamine
In animal foods as pyridoxal (the aldehyde) or as pyridoxol (the alcohol)
An isolated B6 deficiency is almost never seen.
...decarboxylation, heme biosynthesis, and glycogenolysis.
Another critical function is as a cofactor in conversion of L-glutamic acid to gamma-aminobutyric acid, or GABA, which is a key neurotransmitter substance in the brain.
Cobalamin is synthesized exclusively by microorganisms and is, therefore, not present in plants, but can be found in relatively high concentration in animal liver.
When the bound B12 reaches the intestine, the complex is bound to specific cell surface receptors and taken up by pinocytosis. Once absorbed, cobalamin is hydroxylated to form hydroxycobalamin, the form in which it enters cells.
Within cytosol it is converted to methylcobalamin
As that, B12 is involved in reconversion of homocysteine to methionine, generating tetrahydrofolate, a compound critical to methyl-group transfer and DNA synthesis.
Within mitochondrian it is converted to adenosylcobalamin.
As that, B12 is involved in the transformation of methylmalonyl coenzyme A to succinyl CoA, a metabolic conversion required of multitude of biologic substrates for complete degradation.
...lead to a severe clinical disease manifest as methylmalonic acidemia.
The # of glutamate residues, linked as a polypeptide chain, can be varied and the multiple compounds thus formed are called pteroylglutamates. The most active of the latter group is tetrahydrofolate, converted to 5-methylhydrofolate...
leukemias (where the synthetic rate of DNA is extraordinarily accelerated)
Foods rich in folic acid include vegetables and fruits.
...neural tube of the early embryo, resulting in neural tube malformations.
1. Fatty acid synthesis depends upon this process utilizes acetyl coenzyme A carboxylase, produces 3-carbon malonyl CoA.
2. propionyl coenzyme A carboxylase, a rxn producing methylmalonyl CoA
3. betavate carboxylase
4. pyruvate carboxylase
...establish a bond between free biotin and a lysine residue in the carboxylase enzyme protein.
Biotin is present in soy flour, yeast, egg yolk, and liver in high concentrations.
Acyl-group transfer is a key metabolic rxn in fatty acid synthesis and catabolism, amino acid catabolism and normal function of the tricarboxylic acid cycle. Widely found in foods, isolated deficiency not yet described in humans.
Vitamin __ is unlike other vitamins in that it does not bind chemically to a protein in order to function.
Its deficiency causes scurvy, which is...
Vitamin C (Ascorbate)
Scurvy, a disease in which many of the clinical findings - such as gingival hemorrhage and death, hemorrhage into old scars and refracture of old, healed fractures - point to a common effect on collagen metabolism.
...anemia (iron), tetany (calcium), etc.
1. Pharynx: oropharynx and laryngeal pharnyx
2. Foregut: esophagus, stomach, and cranial portion of duodenum from which the primordia of the liver, gallbladder, pancreas arise.
3. Midgut: ?
4. Hindgut: ?
3. Midgut: caudal duodenum, jejunum, ileum, ascending colon, two-thirds of transverse colon incl appendages cecum and vermiform appendix
4. Hindgut: distal third of transverse colon, descending colon, sigmoid colon and rectum
The anterior two-thirds of the upper (oral) portion is separated from the posterior one-third (pharyngeal) portion by the sulcus terminalis.
1: circumvallate papillae - located along the sulcus terminals and possessing taste buds
2: filiform papillae - the most numerous
3: fungiform papillae - relatively few but possessing taste buds
20; deciduous (this dentition lacks premolars (bicuspids) and has 2 not 3 pairs of molars (tricuspids) in each jaw)
...a set of 32 symmetrically arranged permanent (succedaneous) teeth.
2 central incisors
2 lateral incisors
4 premolars (bicuspids)
6 molars (tricuspids)
5: periodontal membrane
6: pulp chamber
7: apical foramen
8: dental pulp
9: tooth wall, enamel, and cementum
Where can the crown, root, alevolus, neck, periodontal membrane, pulp chamber, apical foramen, dental pulp, tooth wall, enamel, and cementum be found?
1: above gum margin
2: 1-3 cm below gum margin
3: root socket in jaw bone
4: junction of root n' crown
5: attaches to the alveolar wall
6: extends from crown into root canals
7: canal opening at tip of root
8: occupies chamber
9: borders pulp
a. moist surface epithelium (containing organ-specific cell types)
b. connective tissue (lamina propria)
c. thin muscular layer (muscularis mucosae)
a. connective tissue
b. plexi of peripheral nerves and ganglion cells termed Meissner's plexus
c. some areas may contain exocrine glands
d. rich in blood vessels
a. inner circular smooth muscle layer
b. outer longitudinal smooth muscle layer
c. Auerbach's myenteric plexus - between the two muscle layers is located a parasympathetic plexus of nerves associated with numerous ganglion cells
a. connective tissue containing blood vessels, nerves, and lymphatics
b. peritoneal covering (mesothelium) located in some regions
The __________ (~10 to 12 in.) has three sections:
Upper: only skeletal (voluntary)
Middle: skeletal and smooth
Lower: only smooth (involuntary)
The cardiac and fundic.
a. surface lining/mucous cells
b. parietal or oxyntic cells
c. chief (zymogenic) cells
d. argentaffin or enterochromaffin cells
1. Duodenum (10 inches)
2. Jejunum (8.5 feet)
3. Ileum (12.5 feet)
C: plasma cells
The plasmalemma associated w microvilli contains proteins (transport carriers) w high specificity for binding w sugars and amino acids. Some transport carriers are linked w the action of Na+-K+ ATPase at opposite pole of epithelial cell.
active transport (against a concentration gradient).
A similar process occurs in the proximal renal tubule. The density of some of these intestinal carrier proteins is genetically regulated.
ascending, transverse, and descending colon
Exocrine glandular elements are arranged in acini. Acinar cells have basal zone (extensive rough endoplasmic reticulum), apical zone of zymogen granules (precursors of enzymes in pancreatic juice [trypsin, chymotrypsin, amylase, lipase]).
trypsinogen->trypsin, chymotrypsinogen->chymotrypsin, procarboxypeptidase->carboxypeptidase
Trypsin, chymotrypsin, and carboxypeptidase attach proteins, polypeptides and eventually render amino acids which can be absorbed.
...that can be identified are:
1.A or alpha cells which are presumed to form glucagon.
2.B or beta cells which are more numerous than A cells and produce insulin.
3.D or delta cells which are the least numerous and produce somatostatin.
1.synthesis/storage of glycogen 2. maintenance of blood glucose homeostatis 3. production of glucose from amino acids 4. synthesis of nonessential amino acids 5. detox of ammonia 6. fatty acid synthesis 7. and catabolism. What of the others?
1. removes bile pigment, derived from hemoglobin breakdown from blood and secretion into the bile 2. synthesis of albumin 3. storage of many lipid and water-soluble proteins 4. drug detox 5. embryonic hematopoietic organ. What of the others?
bile, bile salts, bile acids, and bile pigments
The bile salts and acids, synthesized from cholesterol, are critical for normal fat digestine in the intestine, since they enable micelle formation.
Also, intrinsic factor (antipernicious anemia factor) is secreted.
1. Water and electroytes are reabsored to preserve that delicate balance in the body.
2. Food is propelled along for elimination (egestion).
...(from small intestines) stimulates contractions.
1. mixing of food w secretions, enzymes
2. contact of foodstuffs w intestinal mucosa
3. propulsion along tube (peristalsis)
4. nervous system
5. hormonal secretions
6. intestinal distension
peristalsis is a wave of compression (contraction) that is followed by a regional relaxation.
The gut musculature (smooth) is controlled by the autonomic nervous system.
1) some excitation of salivary secretion
2) decrease of motility and secretion in the stomach and small intestines due mainly to the vasoconstrictive action.
3) inhibition of muscular contraction and intrinsic ganglion cell activity due to...?
1. stimulation of motility and secretion via its supply of the intrinsic plexi and the release of the neurotransmitter acetylcholine
2. release of gastrin
Proteins must be reduced to...
Complex carbohydrates must be reduced to...
Complicated lipids must be reduced to...
Proteins must be reduced to amino acids.
Complex carbohydrates must be reduced to monosaccharides.
Complicated lipids must be reduced to fatty acids and triglycerides.
Needed for rapid/efficient absorption of nutrients and easy transport to liver.
Pepsin, Renin, and Hydrochloric acid
Proteins, Milk protein, Many foods
Peptides, Clotted protein, Smaller units
Pancreatic amylase, Lipase, Trypsin, Chymotrypsin, Carboxypetidase
Starches, fats, proteins, proteins, proteins
Maltose, fatty acids (and glycerol), peptides, peptides, peptides
Maltase, Lactase, Sucrase, Aminopeptidase, Dipeptidase, Nucleases
Maltose, Lactose, Sucrose, Peptides, Dipeptidase, DNA and RNA
Glucose, Glucose and galactose, Glucose and fructose, amino acids x2, nucleotides
Large fat droplets
secretin and cholecystokinin
1. stimulates gastric acid and pepsinogen secretion
2. increases the distension of the stomach and gastric motility
causes pancreas to secrete pancreatic fluid, bicarbonate; stimulates biliary fluid secretion, bicarbonate; potentiates enzymatic response to cholecystokinin; slows gastric motility, emptying; stimulates pepsinogen secretion; inhibits gastrin release
Products resulting from the above processes are further hydrolyzed by enzymes associated with the microvilli of the intestinal cells.
maltose and maltotriose
sucrose, glucose and fructose
...lactose to yield monosaccharide subunits.
Oral Cavity -> Polysaccharides; Disaccharide (maltose) -> Amylase; Disaccharidase (maltase) -> Glucose; Glucose -> In small intestine
Stomach -> NO DIGESTION -> In small intestine
Food Enzyme (end product is largely glucose)
Polysaccharides Intestinal, pancreatic amylase
Disaccharides; maltose disaccharidases; maltase
endo and exopeptidases
Foods=milk protein, proteins (casein); Enzyme=rennin (in newborn), pepsin
End products are smaller peptides and a few amino acids.
All absorption in small intestine as amino acids.
Foods=proteins, polypeptides, dipeptides; Enzymes=trypsin, chymotrypsin, carboxypeptidase (all secreted by pancreas) AND OTHERS.
End products are smaller peptides, few amino acids.
Absorption in small intestine as amino acids.
Stomach -> fats -> absolute minimal digestion -> all absorbed in small intestine
Small Intestine -> fats are emulsified by bile -> intestinal, pancreatic lipase -> fatty acids and glycerol -> all absorbed in small intestine
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