Nutrition and Digestion Flashcards
Diarrhoea
- Frequent watery bowel movements.
- Usually caused by bacterial, viral or protozoan infection.
- Can be fatal, especially in aids patients.
- Mucosa can’t maintain normal levels of electrolytes.
Diverticulitis
- Small hernias or pouches in the large intestine.
- Frequently in the sigmoid colon.
- Risk increases with age.
- Thought to be because of lack of fibre.
- Caused by pressure on the colon.
- Inflamed hernias cause diverticulitis. If the hernias burst and leak into the peritoneal cavity, it can be life-threatening.
Constipation
- Can be caused by lack of fibre, fluids, or exercise.
- Dehydration causes excessively dry faeces which are difficult and painful to excrete.
- Opioid analgesics ad antipsychotics can cause constipation.
- Constipation can cause confusion and aggression, particularly in the elderly.
Diabetes Mellitus Type II
- Linked with obesity
- High blood glucose as the glucose isn’t transported into the cells for metabolic use
- Because the body can’t use glucose for energy, it metabolises fat.
- This produces ketones, which lower pH. Ketones are breathed out and excreted in urine. Smells like acetone
Gastroesophageal Reflux Disease (GERD)
- Gastroesophageal sphincter (aka cardiac sphincter) is reinforced by the diaphragm.
- Pressure on the diaphragm opens the gastroesophageal sphincter and allows gastric juices into the oesophagus, causing heartburn.
- Caused by obesity, pregnancy, and sometimes running.
- Treated with antacids or weight loss.
Factors affecting nutrition
- Lifestyle
- Growth
- Gender
- Culture
- Religion
- Preferences
- Medications
- Psychology
- Mental Illness
Glycaemic index (GI)
- The rate of digestion and absorption of carbohydrates , from 0 - 100.
- High GI foods - rapid digestion and absorption, causes fluctuations in blood glucose.
- Low GI foods - slow digestion and absorption. Better for health.
Types of therapeutic diets
- Liquid diets
- Soft diets
- Bland diets (no meats. Prevents excess HCl production)
- Diabetic
- Lactose free
- Low sodium for hypertension
- High fibre for constipation
- Medication related
Bacterial Flora
- In the large intestine
- Ferment indigestible carbohydrates such as cellulose, producing fatty acids and gas - flatulence
- Also synthesise Vits B and K
The Intrinsic Factor
- Produced by the parietal cells in the stomach linin.
- Moves into the Ilium of the small intestine, where it allows the absorption of Vit B12, which will NOT be absorbed without the Intrinsic Factor.
- B12 is essential for healthy red blood cells
- People without the Intrinsic Factor and no B12 develop Pernicious Anaemia.
Basal Metabolic Rate
The energy the body needs for essential activities while awake, at rest.
Factors affecting Basal Metabolic Rate
- Body size and gender
- Body fat
- Hormone and nervous controls
- Infection / Illness
- Fasting
- Drugs
The five categories of nutrients
Macronutrients (for growth, maintenance, repair, energy)
- Protein
- Carbohydrates
- Lipids
Micronutrients (co-enzymes, needed to metabolise macronutrients)
- vitamins
- minerals
What are nutrients
- chemical substances from te diet
- essential nutrients are those the body can’t synthesise
- essential for good health
- used for growth, maintenance, energy and repair
- metabolised to produce ATP
What is nutrition?
The sum of all interactions between the body and the food it consumes
What is the portal triad
The three portals into/out of the liver.
The portal arteriole provides oxygenated blood to nourish the liver tissue.
The portal vein brings deoxygenated blood from the small intestine to be filtered by the liver (stores glycogen, detoxifies drugs). The filtered blood feeds into the central vein.
The bile duct transports bile from the liver, where it is synthesised, to the gallbladder, where it is stored.
Measuring BMI
weight (kgs)/height (m2)
BMI over 30 considered obese. Waist circumference is a better indicator of health.
Types and functions of cells in the mucosa of the stomach lining
- surface epithelium. Simple columnar epithelial cells that release thick alkaline mucus to protect against gastric acid.
- mucous neck cells - release thin acid mucus, purpose currently unknown.
- chief sells - release pepsinogen, the inactive form of pepsin, which digests protein.
- Parietal cells - release HCl, which activates pepsinogen. Also releases the intrinsic factor.
- Enteroendocrine cells - release chemical messengers into the interstitial fluid of the lamina propria.
The layers of the stomach lining
Mucosa
- surface epithelium
- lamina propria
- muscularis mucosae
Submucosa
Muscularis Externa
- oblique layer
- circular layer
- longitudinal layer
Serosa
Structure of the stomach
- Oesophagus leads to the stomach through the gastroesophageal (cardiac) sphincter.
- Rugae folds in the stomach lining, allow the stomach to expand when full and shrink when empty.
- The pyloric sphincter leads from the stomach to the duodenum
Structure of the oesophagus
- Very floppy.
- The lining is made of stratified squamous epithelial cells to cope with friction.
- The Muscularis Externa (with circular and longitudinal layers) starts as skeletal muscle, then becomes smooth muscle.
The upper GI tract consists of:
- the mouth
- the pharynx
- the oesophagus
- the stomach
- the accessory organs: liver, gallbladder, salivary glands, teeth, tongue
The three salivary glands
- parotid gland
- sublingual gland (below the tongue)
- submandibular gland (below the jaw)
The accessory digestive organs
- teeth
- tongue
- salivary glands
- gallbladder
- pancreas
The seven sections of the large intestine
- caecum
- ascending colon
- transverse colon
- descending colon
- sigmoid colon
- rectum
- vermiform appendix
The components of the alimentary canal
- mouth
- pharynx
- oesophagus
- stomach
- small intestine
- large intestine
- rectum
- anus
The three sections of the small intestine
- duodenum
- jejunum
- ileum
The six processes of the GI system
- Ingestion
- Motility
- Digestion
- Absorption
- Secretion
- Excretion
The three main functions of the GI system
- convert foot into small molecules
- transport them across the cell membranes
- use as an energy source by cells
