Week 3 - are you what you eat? Flashcards
What is an enzyme?
- protein catalyst that increases the rate of a chemical reaction without being used up in the reaction
- highly specific
What are accessory organs of the digestive system?
- primarily glands which secrete fluid into the digestive system
- liver, gall bladder, pancreas
What are the 6 parts of the digestive system?
oral cavity, pharynx, oesophagus, stomach, small intestine, large intestine, anus
What are the parts of the small intestine?
duedenum, ilium, jejunum
What are the parts of the large intestine?
cecum, colon (ascending, transverse, descending), rectum, anal cavity
List and explain the 6 functions of the digestive system (in order)
- ingestion: food into digestive tract via stomach
- mastication: chewing, large –> small surface area to facilitate chemical digestion
- secretion: lubricate, liquify, digest
- digestion: mechanical and chemical digestion of food into nutrients
- absorption: nutrients from digestive tract into cells
- elimination: waste products removed as faeces during defecation
What are the layers of the digestive system?
- mucosa: innermost layer, secretes mucus
- submucosa: connective tissue layer containing blood vessels and nerves
- muscularis: 2/3 muscle layer, movement and secretion
- serosa/adventitia: outermost layer, connective tissue, stability
What are mesenteries?
connects organs together; routes by which vessels and nerves pass from body wall to organs
- greater omentum: stomach to transverse colon
- lesser omentum: stomach to liver and diaphragm
What is the palate?
- hard: anterior, hard bone
- soft: posterior, soft muscle
How many teeth do adults have?
32
What are the teeth types and their function?
incisors: biting
canines: tearing
premolars: grinding and crushing
molars: grinding and crushing
What is the purpose of salivary glands?
produces and secretes saliva
What is the function of saliva?
moistens and lubricates, protects oral cavity, contains salivary amylase (digests carbs) and lysozyme (antibacterial)
What enzymes are found in saliva?
Salivary amylase: digests carbs
Lysozyme: antibacterial
What is the function of the pharynx?
- throat
- connects oral cavity to the esophagus
What is the purpose of the uvula?
-prevents food/drink from entering the pharynx
What is the esophagus?
A tube that connects the pharynx to the stomach, 25cm long, is posterior to the trachae
What is the epiglottis?
prevents food and drink from entering the trachea (flap)
Describe the three phases of swallowing
- voluntary phase: tongue pushes bolus to back of oral cavity towards oropharynx
- pharyngeal phase: soft palate (uvula) closes off nasopharynx, bolus touches receptors on oropharynx and swallowing reflex is initiated, epiglottis covers trachea
- esophageal phase: bolus moved down esophagus by peristalsis
What is peristalsis?
the process by which food moves through the gut, waves of smooth muscle relaxations and contractions
What is the process of peristalsis?
Wave of relaxation moves ahead of bolus, allowing bolus to pass downwards
Waves of contractions occur behind the bolus to propel bolus downwards into relaxed part of esophagus.
What is contained in, and occurs in, the stomach?
Bolus moves into the stomach and is now called chyme (thick, soupy liquid)
The stomach produces mucus, HCL, and pepsin (digests protein)
What are the sphincters of the stomach?
cardiac/gastroesophageal and pyloric
What are the parts of the stomach?
cardiac, fundus, body and pyloric
What are the layers of the stomach?
- visceral peritoneum
- muscularis –> outer longitudinal, middle circular, inner oblique
- submuscosa
- muscosa
What are rugae?
Folds in the stomach that allow for stretching after eatting
How often does the stomach empty?
every 4 hours, or 6-8 after a fatty meal
What are the divisions and lengths of the small intestine?
small intestine = 6m
duodenum = 25cm
jejunum = 2.5m
ilium = 3.5m
What three mechanisms increase the surface area of the small intestine?
- plicae ciruclaris - small circular folds in the wall
- villi - folds in mucosa, contains blood vessels and lacteals
- microvilli - small folds on epithelial cell surface
What is the role of the liver?
makes roughly 100mL of bile a day, stores glucose as glycogen, detoxification
What is the role of the gall bladder?
stores and concentrates bile and releases bile after fatty meals
What is the role of the pancreas?
produces lipase, pancreatic amylase, trypsin
What is the role of the large intestine?
water absorption and vit K and B synthesis by microbes
What are the 6 classes of nutrients?
carbs, lipids, proteins, vitamins, minerals, water
Why are chemicals taken into the body?
- produce energy
- provide building blocks for other materials
What are the building blocks of carbs?
monosaccharides
What are the building blocks of proteins?
amino acids
What are the building blocks of lipids?
triglycerides (fatty acids and glycerol)
What is the recommended amounts of carbs, proteins and lipids?
carbs: 45-65%
lipids: 20-35%
proteins: 10-35%
What is an example of a monosaccharide, disaccharide and polysaccharide?
monosaccharide: glucose, fructose, galactose
disaccharide: sucrose, lactose, maltose
polysaccharide: glycogen, starch, cellulose
What are uses of carbs in the body?
- ATP production
- storage in the liver and muscle cells
- DNA, RNA, ATP, glycoproteins, glycolipids
What is the structure of an amino acid?
R group, amine group, carboxyl group
What is the difference between essential and non-essential amino acids?
essential: can’t be produced in the body, 9
non-essential: can be synthesised by essential amino acids
What is the difference between a complete and incomplete protein?
complete: food that contains all 9 essential amino acids, eg fish, meat, poultry, cheese, eggs
incomplete: food that doesn’t contain all 9 essential acids, eg leafy greens, grains, legumes, grains
What is the difference between saturated, unsaturated and trans fat?
Saturated: all C bonds taken by H
Unsaturated: some C=C bonds, H can be added
Trans fat: unsat fats that have been artificially altered to be more saturated
What are some uses of lipids in the body?
- ATP
- cholestrol used as a component of plasma membrane, bile salts
- phosopholids - forms cell membrane
- eicoanoids - involved in inflammation, blood clotting, tissue repair, smooth muscle contraction
Vitamins
essential for normal metabolism, can’t be produced by the body, organic
Minerals
inorganic, components of co-enzymes, vitamins, haemoglobin, organic molecules, membrane potential and action potential, mechanical strength to bones and teeth
