Compendium 3. Are you what you eat? Flashcards
What is an enzyme?
An enzyme is a protein that is able to catalyse specific chemical reactions without themselves being altered. They speed up the rate at which reactions occur within the body.
What are some features of enzymes?
- Enzymes are highly specific - an active site on an enzyme can only bind with a specific substrate/reactant
- Each enzyme can only work under specific conditions (pH level and temp)
- Enzymes can be denatured by heat
What are the 7 components of the digestive system?
- Oral cavity and salivary glands
- Pharynx
- Oesophagus
- Stomach
- Small intestine (along with the liver, gall bladder and pancreas as the accessory organs)
- Large intestines
- Anus
What are the 6 functions of the digestive system?
- Ingestion
- Mastication
- Secretion
- Digestion
- Absorption
- Elimination
Name and briefly describe the 4 layers of the digestive tube
- Muscosa - The innermost layer that secrets mucous (the epithelial layer)
- Submucosa - The second most inner layer which contains a large supply of blood vessels and nerves (the connective layer)
- Muscularis - Made of smooth muscle and is i important in peristalsis
- Serosa/Adventitia - The outermost layer that is important for stability (also made of connective tissue)
What is the peritoneum?
The serous membrane inside the abdominal pelvic muscle
What are the 3 components of the peritoneum ?
- Visceral
- Parietal
- Mesenteries
What is the mesenteries?
Epithelial tissue which connects organs together
Greater omentum - connects the stomach to the transverse colon
Lesser omentum - connects the stomach to the liver and diaphragm
What are the 3 phases of swallowing?
- Voluntary phase - the tongue pushes the bolus towards the back of the throat.
- Pharyngeal phase - uvulva closes of the nasopharynx and the bolus touches receptors that trigger the swallowing reflex
- Oesophageal Phase - the bolus is moved down the oesophagus towards the stomach by peristalsis
What is peristalsis?
The mechanism of food moving along the alimentary canal which is controlled by smooth muscle
What is the main function of the oral cavity?
- Masticates food and breaks it down into smaller components
- Creates the bolus
What are the main components of the oral cavity?
- The hard palate
- The soft palate
- Tongue
- Teeth
- Salivary glands
What are the main roles of saliva in digestion?
- Protects the oral cavity
- Secretes amylase (which break down carbs into smaller sugars)
- Secretes lysozymes (antibacterial enzymes)
What are the main functions of the pharynx?
- Uvula prevents food from entering the nasopharynx
- Connects the mouth to the oesophagus
What are the main functions of the oesophagus?
- The epiglottis prevents food from entering the trachea
- Connects the pharynx to the stomach
What are the main functions of the stomach?
- Mixes and churns food to become soupy liquid called chyme
- Produces protein digesting enzymes
What are rugae?
Rugae are the folds in the stomach which allow the stomach to stretch and increase surface area
How often does the stomach empty into the small instestines?
Every 4hrs or 6-8 after a fatty meal
What are the two openings of the stomach?
- Gastroesophageal (cardiac) from oesophagus
2. Pyloric to the duodenum
What is the main function of the small intestine?
The absorption of nutrients and water
What are the 3 divisions of the small intestine?
- Duodenum
- Jejunum
- Ileum
What is the main role of the liver and gallbladder in digestion?
Produces and stores bile
What is the main role of bile?
Breaks down fats and lipids through the process of emulsification
Briefly explain the process of bile moving from the liver to the alimentary canal
- Bile is formed in the liver.
- It is then stored in the gall bladder
- When a fatty meal has been consumed, the bile will move from the gall bladder into the small intestine and goes onto break down fats
What is emulsification?
The break down of fat globules into tiny fat droplets, creating a larger surface area - making it easier for digestion by lipases
What are the main roles of the pancreas in digestion?
- Produces digestive enzymes which break down lipids, carbs and proteins
- Important in sugar metabolism
What is the main function of the large intestine?
Absorption of water
What are the divisions of the large intestine?
- Cecum
- Colon (ascending, transverse, descending and sigmoid)
- Rectum
- Anal canal
What are the 3 main roles of nutrients?
- Produce energy
- Provide the building blocks to build other molecules
- To maintain homeostasis
What are the 6 classes of nutrients?
- Carbohydrates
- Proteins
- Lipids
- Vitamins
- Minerals
- Water
What are the recommended daily amounts of carbohydrates, lipids and proteins?
Carbs - 45-65%
Lipids- 20-35%
Proteins - 10-35%
What are kilocalories?
The measurement of energy we get from food
What types of foods are high in carbs?
- vegetables
- pasta
- rice
- cereals
- milk
What are monosaccharides? Provide some examples
1 chain of sugar molecules
- glucose
- fructose (fruit sugar)
- galactose (milk sugar)
What are disaccharides? Provide some examples
2 chains of sugar molecules
- sucrose (glucose + fructose)
- lactose (glucose + galactose)
- maltose (glucose + glucose)
What are polysaccharides? Provide some examples
Long chains of 300+ monosaccharides
- glycogen
- starch
- cellulose
What are the uses for carbohydrates in the body?
- Glucose is used to produce ATP
- Sugars can become apart of DNA and RNA
- Excess glucose can be stored as glycogen and fat
What types of foods are high in protein?
- meat
- nuts
- eggs
- legumes
- dairy products
What are the basic building blocks of proteins?
amino acids come together to form peptides, which come together to form polypeptides, which come together to form proteins
What are essential and non essential amino acids?
Essential - amino acids that are not produced by the body and thus must be obtained from diet.
Non-essential - amino acids that are still required by our body, however they can be synthesised from essential amino acids.
What are the uses of proteins in the body?
- Used to make enzymes, hormones and antibodies
- Muscle strength and repair
- Used in the formation of cartilage, bones, muscles, skin and blood
- Important in cell membrane transport
What are complete and incomplete food sources? Provide examples of both
Complete - contain all 9 essential amino acids
- meat
- fish
- milk
- cheese
- eggs
Incomplete - only contain a few amino acids
- leafy green vegetables
- grains
- legumes
What types of food are high in lipids/fat?
- dairy
- oils
- animal fat
- eggs
What are triglycerides made up of?
glycerol + 3 fatty acids
Triglycerides make up 95% of fats in the body
What are the features of fatty acids?
- They have different lengths
- They can different levels of saturation (the amount of H atoms on each chain)
What are the different types of ‘saturation’ of fatty acids?
Saturated - fatty acids that come from animal fat eg beef, pork, milk etc
Unsaturated - fatty acids that come from plant sources eg olive oil, avocado. Unsaturated fats are considered healthier
Trans - fatty acids that are often unsaturated and are artificially altered to become more saturated eg fast foods, deep fried. Trans fats can be quite dangerous and pose cardiovascular risk
What are the uses of lipids in the body?
- Used in the production of ATP
- (Cholesterol) Components in plasma membranes, used in the formation of bile salts, (phospholipids) myelin sheath.
Approximately how much water enters the digestive tract each day? How much of this is absorbed?
9L
99% of the water that enters the intestine is absorbed
What are vitamins?
Organic molecules that are essential for normal metabolism but only in very small quantities.
Vitamins cannot be produced by the body.
Give some examples of fat and water soluble vitamins
Fat soluble - A, D, E, K
Water soluble - B, C
What vitamins are produced by the bacteria in the intestines?
B and K
What are the uses of minerals within the body?
- They make up co-enzymes, some vitamins, haemoglobin and organic molecules
- Calcium adds mechanical strength to bones and teeth
- Copper, zinc and selenium are used as antioxidants
What are major and trace minerals?
Major - more than 100mg/day
- calcium
- sodium
- potassium
Trace - less than 100mg/day
- copper
- zinc
- selenium
