Vitamins, Minerals and Nutrition Flashcards
DRVs =
Dietary Reference Values
= estimates of the energy and nutrients needed by different groups of healthy people in the UK
Estimated Average Requirement (EAR) =
The level of a nutrient required to satisfy about 50% of the population
Reference Nutrient Intake (RNI)
Set 2 standard deviations above the mean (EAR) and will meet the individual requirements of 97.5% of the population
GDAs
Guideline Daily Amounts
Intended as guidance for consumers in their understanding of their recommended daily consumption of energy (calories), fat and saturates and a base against which the content of individual foods can be compared
Currently no GDAs for children
BMR (Basal Metabolic Rate)
Approx 60% of energy obtain by food oxidation used to maintain body function = basal metabolic rate
e.g. heart beat, inflating lungs, maintaining ion gradients, synthesising bio-molecules e.g. proteins, hormones, DNA, RNA, fat etc.
Small Intestine
- Duodenum (proximal)
o First part of small intestine
o Receives secretions from pancreas (enzymes for protein digestion) and bile from gallbladder to aid digestion - Jejunum (middle)
- Ileum (distal)
o Inner surface highly folded into villi – increases SA for absorption
Attached to body wall by mesentery
Function: Nutrient Absorption
Large Intestine
- Constitutes o Caecum o Ascending colon o Transverse colon o Descending colon o Sigmoid colon o Rectum o Anal canal
- Function
o Water absorption
o Formation of faecal mass
o Secretion of mucus
Accessory Organs of GI tract
Pancreas – enzyme secretion into duodenum
Liver
- Bile production
- Detox – drugs, alcohol
- Albumin production – protein that maintains osmotic pressure
- Production of clotting factor precursors
- Storage of glycogen
Gallbladder – stores and secretes bile into duodenum; emulsifies lipids
Omentum
- Covers GI tract
- Consists of greater and lesser omenta
- Greater omentum hangs from greater curvature of stomach like a curtain, also contains extra-peritoneal tissue; lymph nodes, lymph vessels, small blood vessels, variable amounts of fat. Has irregular lacy appearance.
Peritoneum
= membranes of the abdomino-pelvic cavity
Visceral peritoneum: covers external surfaces of most digestive organs
Parietal peritoneum: lines body wall
Peritoneal cavity = potential space between the two
Peritoneal fluid = normal lubricating fluid found in peritoneal cavity
digestion of carbohydrate in the oral cavity
Oral cavity → Mechanical (mastication exposes terminals to enzymatic action) + Chemical (enzymatic – salivary amylase secreted from serous cells in salivary glands)
Salivary amylase
- Secreted by serous acini of parotid and submandibular salivary glands
- Optimal pH= 6.7
- Action begins in oral cavity, assisted by mechanical breaking up of polysaccharides during mastication
- Mode of action = hydrolysis of α-1-4 linkage in polysaccharides → mixture of oligosaccharides (di/tri-saccharides)
- Works for 1/2hrs in stomach before being deactivated by gastric acids
digestion of carbohydrate in GIT
GIT → Chemical (enzymatic)
Pancreatic amylase
- Secreted from pancreatic exocrine acini into duodenum through the pancreatic duct – along with bicarbonates raises pH to optimum for amylase to work
- Optimum pH=6.7-7.0
- Mode of action = hydrolysis of α-1-4 linkage
- Responsible for digestion of more complex carbohydrate, take longer to break down to disaccharides (maltose) or oligosaccharides (dextrins)
NB: salivary & pancreatic amylases cant completely digest carbohydrates
- *Brush border enzymes: Maltase, Sucrase, Lactase **
- Found on membrane surface of micro-villi (brush border) of epithelial cells lining small intestines
- Optimal pH=7-8
- Mode of action = hydrolysisng disaccharides → monosaccharides
absorption of glucose from the small intestine at the cellular level
Villi & Microvilli (brush border) -> Increase SA, facilitates absorption
Monosaccharides = absorbable form of carbs
Glucose & Galactose
- Enter epithelial cells of intestine through the apical border via active transport (against concentration gradient) using sodium dependant co-transporters (Na-K pump requires energy)
- Leave the cells through the Basolateral side using facilitated diffusion and glucose co-transporter- 2 (GLUT-2) into the circulation (no energy required)
Fructose
- Enters (GLUT-5) and leaves (GLUT-2) the epithelial cells using facilitated diffusion (no energy required)
Factors affecting carbohydrate absorption
- Faster through intact mucosa; absorption decreased if inflammation or injury to the mucosa.
- Thyroid hormones ↑ the rate of absorption of glucose.
- Mineralocorticoid: e.g. Aldosterone ↑ the rate of absorption.
- Na+ concentration: high concentration ↑ the rate of absorption
role of insulin in glucose homeostasis
Insulin = hormone secreted by ß-cells in islets of Langerhans in pancreas (endocrine glands)
Responsible for regulating levels of glucose in blood by stimulating body cells to take up glucose – all body cells sensitive to insulin except: brain, liver and muscles during exercise
Structure of Insulin:
2 polypeptide chains A & B linked by a disulphide bond
Glucagon
= hormone secreted by α- cells in islets of Langerhans in pancreas
Responsible for converting glycogen stored in liver -> glucose and releasing it in blood when blood glucose levels low
Also stimulates gluconeogenesis from untraditional mechanisms (fat/protein sources) – used in case of starvation
➢ Clinical significance of insulin deficiency
Insulin deficiency (Type 1 – autoimmune disease) Insulin resistance (Type 2 – unresponsive cells)
–> leads to hyperglycaemia (causes the symptoms and complications of diabetes) and diabetes mellitus.
➢ Symptoms and complications of diabetes and its relevance to oral health and dental management
impaired wound healing
dry mouth
nausea
yeast infections
Diabetes -> damage to blood vessels -> more susceptible to collecting cholesterol -> blockage of blood vessels: macrovascular, microvascular
Dental Complications:
- Dry mouth
- Periodontal disease
- Loss of teeth
- Impaired/delayed healing
- Infections
Dental management of diabetic patients
• Regular visits to dentist and dental hygienist
• Maintenance of oral hygiene
• Regular periodontal check and management
• Antibiotic coverage for surgeries (surgical extraction, implants)
• Controlled blood sugar levels before any surgical intervention
• Mouth wash
• Artificial saliva if required
Nutrition and Caries
proteins - can adsorb to enamel surface and prevent remineralisation
dehydration -> reduced salivary flow
Caesin (milk protein) promotes natural remineralisation
fluoride insufficient -> caries prone
fluoride excess -> fluorosis
Vit D deficiency -> decreased Ca -> poorly mineralised enamel, enamel hyperplasia, rickets
Vit E def (rare) -> disturbed enamel formation
Vit A def -> enamel hyperplasia and malformed dentine
fermentable dietary components (carbohydrate)
pyruvate -> lactic acid/acetic acid
sucrose = worst carb
- bacteria can use to produce extracellular polymer
sucrose = glucose + fructose
Glucan (polymer of glucose) + Fructan (polymer of fructose) -> plaque
sugar substitutes = non-fermentable
Nutrition and Periodontal disease
nutrition modulates immune response .’. poor nutrition -> poor wound healing
vit A -> essential in maturation of epithelial tissues
vit D -> maintains blood Ca levels and metabolism of osseous (bony) tissues - may be associated with periodontal disease
vit C *(humans can’t make it C = essential vit) -> required for collagen maturation
deficiency -> tissue bleeding, marked gingivitis, increased risk of period disease
vit B complex -> can increase periodontal wound healing
dairy - inverse relationship between intake and period
alcohol - may be associated with increased severity of CAL
fish oils -> anti-inflammatory actions
