Compendium 3- Questions Flashcards
Name the six classes of nutrients
1- carbohydrates 2- lipids 3- proteins 4- water 5- vitamins 6- minerals
Give an example of a monosaccharide, disaccharide, polysaccharide
1- glucose, fructose, galactose
2- sucrose, lactose
3- starch, cellulose
What makes up a triglyceride ?
glycerol + 3 fatty acids
What is the difference between saturated and unsaturated fat?
saturated: hydrogen molecule attached to every carbon molecule
unsaturated: does not have a hydrogen attached to every carbon
What is a polypeptide?
Chain of amino acids linked together
Name a disorder caused by a vitamin deficiency
Vitamin D: rickets
Vitamin C: scurvy
Vitamin B1: beriberi
What is an enzyme?
Protein that increases rate of reaction but not permanently changed by the reaction
What enzyme is produced by the pancreas?
pancreatic amylase, lipase, trypsin
What are the functions of the digestive system
1- Ingestion:
introduction of food into stomach (via mouth)
2- Mastication:
chewing. Chemical digestion requires large surface area so breaking down large particles mechanically facilitates chemical digestion
3- Secretion:
lubricate, liquefy, digest (e.g. Mucus: secreted along entire digestive tract, lubricates food, coats and protects lining)
4- Digestion:
Mechanical and chemical digestion of food into nutrients
5- Absorption:
Movement of nutrients out of digestive tract into cells
6- Elimination:
Waste products removed from body; faeces. Defecation
Peritoneum
- Walls and organs of abdominal cavity lined with serous membranes
Visceral: covers organs
Parietal: Covers interior surface of body wall
Mesenteries: peritoneum (epithelial tissue) connects organs together. Routes by which vessels and nerves pass from body wall to organs - Greater omentum:
Connects stomach -> transverse colon - Lesser omentum:
Connects stomach -> liver & diaphragm
Oral cavity
- Digestion begins here
- Masticate (chew) food into a bolus
Structure
Hard palate: Hard bone, anterior
Soft palate: Soft muscle, posterior
Tongue
Teeth: Incisors, canines, premolars, molars.
Salivary glands: produce and secrete saliva into oral cavity
Saliva: protects oral cavity, moistens, lubricates & digests food
Amylase: enzyme in saliva breaks down carbohydrates -> smaller sugars
Lysozyme: antibacterial enzyme
Pharynx
- Connects oral cavity to oesophagus
- Uvula (soft palate) prevents food/drink from entering nasopharynx
Oesophagus
- Tube connects pharynx to stomach
- Posterior to trachea
- Epiglottis prevents food/drink from entering trachea
Oesophagus: swallowing phases
1- Voluntary:
- Tongue pushes bolus back of oral cavity towards pharynx (oropharynx)
2- Pharyngeal:
- Soft palate close off nasopharynx
- Bolus touches receptors on oropharynx
- Swallowing reflex moves bolus down pharynx -> oesophagus
- Epiglottis covers trachea.
3- Oesophageal
- Bolus moved down oesophagus -> stomach by peristalsis
Oesophagus: Peristalsis
- Process by which food moves through the gut
- Waves of smooth muscles relaxations & contractions
Stomach
- Located in abdomen
- Food comes from oesophagus; stomach mixes into chyme
- Produces mucus, hydrochloric acid, protein digestive enzymes (pepsin)
Contains thick mucus later; lubricates and protects epithelial cells on stomach wall from acid
Stomach: structure
Openings: Gastroesophageal -> oesophagus Pyloric -> duodenum Parts Cardiac Fundus Body Pyloric: antrum and canal Layers Visceral peritoneum Muscularis: Three layers; Outer longitudinal, middle circular, inner oblique Submucosa Mucosa Rugae: folds in stomach wall that allow stomach to stretch after eating.
Stomach: Movements
- 3 muscular layers enable churning of food; makes chyme
- Combined mixing and peristalsis waves
- Oesophageal and pyloric sphincters are closed
- Empties every 4hrs (6-8hrs after high fat meal)
Small intestine
- Very long, small diameter
- Large surface area for efficient absorption of nutrients
Plicae circulares:
Circular folds in wall of small intestine
Villi:
Folds of mucosa contains capillaries & lacteals
Microvilli:
Small folds on epithelial cell surface - Lipid -> lacteals -> lymph
- Carbs & proteins -> capillaries -> blood
- Divisions: Duodenum, jejunum, ileum
Small intestine: duodenum
- Chyme mixes with digestive enzymes
- Lipase: Breakdown lipids
- Pancreatic amylase: Breakdown carbohydrates
- Trypsin: Breakdown proteins
Large intestine
- Absorption of water
- Extends from ileocecal junction to anus
- Consists of: cecum, colon (ascending, transverse, descending, sigmoid), rectum, anal canal
- Bacterial/microbes synthesis vitamin B&K.
- 18-24hr transit time; chyme -> faeces
- Chyme enters cecum, 90% reabsorbed; remainder is faeces
List the basic histological layers of digestive tract
1- Mucosa:
innermost layer, secrets mucus.
2- Submucosa:
connective tissue layer, contains blood vessels, nerves etc.
3- Muscularis:
2/3 muscle layers, movement & secretion.
4- Serosa / Adventitia:
outermost layer, connective tissue, stability.
List the accessory organs of the digestive system
- Not apart of the digestive tract but has a role in digestion.
1- Liver:
Bile enters via common bile duct - emulsifies fats
2- Gallbladder:
Bile enters via common bile duct - emulsifies fats
3- Pancreas:
Enzymes enter via pancreatic duct
State the contribution of the liver
- Makes bile
- Stores glucose (as glycogen) + lipids for energy
- Detoxification
State the contribute of the gallbladder
- Stores concentrated bile
State the contribution of the pancrea
- Produces digestive enzymes
- Produces insulin + glucagon for blood sugar homeostasis
Explain the difference between digestion and absorption
1- Digestion:
- Mouth, stomach, small intestine
- Breakdown food molecules for absorption into circulation.
Mechanical: Large food particles to smaller particles
Chemical: Breaking covalent bonds by digestive enzymes
2- Absorption:
- Small + large intestine
- Nutrients absorbed from small intestine
- Water absorbed from large intestine
Molecules moved out of digestive tract -> circulation for distributions throughout the body
Describe carbohydrates
Mostly from plants
2H:1O:1C ratio
Describe the 3 types of carbohydrates
1- Monosaccharide
- Glucose (blood), fructose (fruit), galactose (milk)
2- Disaccharide
- Sucrose = glucose + fructose
- Lactose = glucose + galactose
- Maltose = glucose + glucose
3- Polysaccharide
- 3000+ monosaccharide
Glycogen: stored in liver and muscle , animal polysaccharide, glucose molecules
Starch & cellulose: plant polysaccharide, starch break down for energy, cellulose cannot be broken down; dietary fibre.
Describe how polysaccharide is absorbed
- glycogen
- digested by saliva (oral cavity) and pancreatic amylase (duodenum)
Describe how disaccharide is absorbed
- sucrose
- digested by sucrase in intestine
describe how monosaccharide is absorbed
- glucose
- absorbed into blood via villi/microvilli in small intestine
- transported to liver via hepatic portal vein
What are the uses of carbohydrates in the body?
glucose -> ATP production
excess glucose -> into glycogen & stored in muscles and liver cells
excess beyond storage converted to fat
Describe proteins
- Contains C, H, O, N, S
- Side groups make different amino acids
- Amino acids link to form peptides and proteins
- Not stored in the body
- Essential: Cannot be produced by the body, obtained through diet.
- Non-essential: Still required, synthesised by essential amino acids
- Complete: Contains enough of all essential amino acids (milk, cheese, eggs, meat & fish)
- Incomplete: Does not have all essential amino acids (green vegetables, grains, legumes)
Function of proteins
- Regulate body functions ▪ Cell membrane transport ▪ Hormones ▪ Antibodies ▪ Globular proteins (haemoglobin)
Protein absorption
1- Protein
- Digested by pepsin in stomach
2- Polypeptides
- Digested by trypsin in duodenum
3- Peptides & individual amino acids
- Absorbed into blood via villi/microvilli in intestine
Lipids
- Composed of C, H, O, N, P
- Lower ratio of O -> C than carbs
- Relatively insoluble in water
- Broken down to release energy
- Triglycerides make up 95% fats in the body
triglycerides
- Glycerol + 3 fatty acids
- Fatty Acids
- Different lengths
- Saturation: No double bonds, all hydrogen is bonded to carbon
- Unsaturated: Double bonds present, less hydrogen bonded to carbon atom
- Trans fats: Unsaturated fats artificially altered to be more saturated.
Lipid absorption
1- Lipid (triglycerides) - Digestion begins in duodenum 2- Bile - From gall bladder emulsifies lipids 3- Lipase - From pancreas, further breakdown 4- Monoglycerides - Absorbed into lymphatic system via lacteals 5- Lipids - Stored in adipose tissue and liver
Use of lipids
Triglycerides: used to produce ATP (excess stored in adipose/liver)
1- Cholesterol (liver & egg yolks):
Component of plasma membranes, modified to form bile salts.
2- Phospholipids:
Major component of plasma membrane, myelin sheath, part of bile
3- Eicosanoids (fatty acids):
Involved in inflammation, blood clots, tissue repair, smooth muscle contraction
Recommended amounts of carbohydrates, lipids and proteins
1- Carbohydrates: 45-65%
2- Lipids: 20-35%
3- Proteins: 10-35%
List the basic building blocks of carbohydrates, lipids and proteins
1- Carbohydrates: Monosaccharides; carbon, hydrogen, oxygen
2- Lipids:
Triglycerides = glycerol + 3 fatty acids
3- Proteins:
Amino acids = amine group + carboxyl group + hydrogen + side group
Distinguish between vitamins and minerals
1- Vitamins - Very small quantities in food - Organic molecule - Essential for normal metabolism - Cannot be produced by the body - Fat soluble vitamins: A, D, E, K - Water soluble vitamins: B, C 2- Minerals - Inorganic nutrients - Essential: Calcium, magnesium, sodium, potassium - Less essential: selenium, zinc, copper - Components of co-enzymes, some vitamins, haemoglobin, organic molecules - Available from plant and animals Functions: - Membrane potential - Action potential - Mechanical strength to bones and teeth
List the conditions as a result of too much vitamins
Vitamin C: Stomach inflammation; diarrhea
Vitamin A: Toxic during pregnancy
Vitamin D: Alter calcium metabolism
List the conditions as a result of vitamin deficiency
Vitamin D: Rickets
Vitamin C: Scurvy
Vitamin B: Beriberi
List the conditions as a result of mineral deficiency
Iron: Anaemia
Potassium: Muscle weakness, abnormal heart function
Iodine: Goitre
Describe the function of enzymes within the body
- Increase the rate of chemical reactions
- Is not used up in a chemical reaction
- Highly specific; active site on enzyme will only bind to a specific reactant.
- Different enzymes needed for different reactions
e. g. Of enzymes
a) Lipase: breaks down lipidsb) Protease: breaks down proteins
