Ch28: Human Nutrition Flashcards
What is an autotroph?
Makes their own food
What is a heterotroph?
Take in food from the environment
What is a parasite?
A heterotroph that feeds on live sources
What is a saprophyte?
A heterotroph that feeds on dead matter
What is a herbivore?
Animals that feed mainly on plants
What is a carnivore?
Animals that feed mainly on other animals
What is an omnivore?
Animals that feed on both plants and animals
Other names for digestive system?
Alimentary canal or gut
Why do organisms need to digest food?
-Energy
-Growth and repair
-Metabolic reactions
Why do we need the digestive system?
So that digestive enzymes are not needed in every cell in the body, like tapeworms
Name and explain the four processes involved in the digestive system
-Ingestion: taking in food
-Digestion: breakdown of food
-Absorption: food passes into blood
-Egestion: removal of undigested food
Name the types of teeth and their functions
-Incisors: for cutting and slicing
-Canines: for gripping and tearing
-Premolars: for crushing and grinding
-Molars: for crushing and grinding
How many teeth does an adult human have and write the Dental formula
32 teeth
2(I 22, C 11, P 22, M 33)
Name and explain the two types of digestion in the mouth
-Chemical digestion: action of the enzyme, amylase, breaking down food
-Mechanical digestion: chewing and grinding action of teeth breaks down food
What does saliva contain?
Water, salts, lysozyme (destroys bacteria) and amylase
Amylase:
1. Production site
2. Activity site
3. Substrate
4. Product
5. Optimum pH
- Salivary glands/ Pancreas
- Mouth/Duodenum
- Starch
- Maltose
- pH7
What is the function of the epiglottis?
A flap of cartilage that closes over the trachea to ensure food passes into the oesophagus
Function of oesophagus?
Carries food from the mouth to the stomach by peristalsis
What is peristalsis?
A wave of muscular actions in the wall of the alimentary canal that moves the contents along
-form of mechanical digestion
What is the role of fibre in the digestive system?
Fibre stimulates peristalsis by causing waste to absorb water and expand
Function of the stomach?
-Muscular bag that holds and digests food
-Churns food with gastric juice to form chyme
Name and explain the 2 types of digestion in the stomach
-Mechanical digestion: Churns food
-Chemical digestion: action of gastric juice
What is the role of mucus?
Coats the stomach to prevent self-digestion
Role of hydrochloric acid in the stomach?
-Gives a pH of 1-2
-Kills bacteria
-Loosens food
-Activates pepsinogen
Explain the protease used in the stomach
-Pepsinogen is inactive so that it does not digest the stomach lining but is then converted to the active enzyme pepsin (protease)
- Production site- stomach lining
- Activity site- stomach
- Substrate- proteins
- Product- peptides
- Optimum pH- 2
Pepsinogen is secreted by the stomach lining but is inactive to prevent self-digestion
It is converted to the active enzyme pepsin, which is a protease, in the stomach.
It breaks down proteins into peptides and works at a pH of 2
Functions of the pancreas?
-Secretes insulin
-Secretes pancreatic juices (sodium bicarbonate, amylase and lipase) that enters the duodenum through the pancreatic duct
-The sodium bicarbonate is a base and neutralises the chyme
Lipase:
1. Production site
2. Activity site
3. Substrate
4. Product
5. Optimum pH
- Pancreas
- Duodenum
- Lipids
- Fatty acids and glycerol
- 7-9
Functions of the liver?
-Breaks down red blood cells
-Converts glucose to glycogen for storage
-Breaks down poisons, such as alcohol and drugs
-Breaks down excess amino acids to form urea
-Converts excess carbohydrates to fat
-Makes bile **
BBBCCM
Describe bile
-Yellow, green, viscous liquid
-Made from water, bile salts and bile pigments
-Made in the liver and stored in the gallbladder
-Enters the duodenum through the bile duct
Functions of bile
-To emulsify lipids
-To neutralise chyme
-To excrete pigments (bilirubin and biliverdin) made from damaged red blood cells
Name the two parts of the small intestine
-Duodenum
-Ileum
Functions of the duodenum?
-To digest food
-Cells of the duodenum produce enzymes
-Products of the pancreas and liver enter the duodenum
Function of the ileum?
To absorb nutrients
Adaptations of the small intestine for its function?
-Long to allow time for absorption
-Has large numbers of infoldings called villi to increase surface area for absorption
-Each villus is covered in many microvilli
-Wall is only 1cm thick, to allow diffusion of food
-Villi have a rich blood supply to transport nutrients
What is a lacteal?
-Inside the villus
-Each lacteal contains lymph (fluid)
-Fatty acids and glycerol are absorbed into the lacteal and transported to the blood
Function of the villus?
-All digested food, except fatty acids and glycerol, are absorbed into capillaries
-Capillaries carry the food to the hepatic portal vein and to the liver
-Excess amino acids cannot be stored in the liver, so they are broken down to form urea in a process called deamination
Success criteria of the LS and a TS of a villus
LS:
-villus
-Lacteal
-Lymph
-Microvillus
-Capillaries
-Venule
-Muscular wall
-Lymph vessel
-Arteriole
TS:
-Muscular wall
-Food
-Villus
Name the parts of the large intestine
-Caecum
-Appendix
-Colon (Ascending, Transverse, Descending)
-Rectum
-Anus
Functions of the caecum and appendix?
-Not fully known
-Many herbivores use bacteria in the caecum and appendix to digest cellulose
-Known as vestigial organs (organs that have lost their former use)
Functions of the colon?
-To reabsorb water using osmosis ***
-Liquid waste is converted to faeces here
-Faeces are stored in the rectum before being egested (not excreted)
What are symbiotic bacteria?
Bacteria that obtain food and shelter from humans and provide useful functions in return
Give examples of symbiotic bacteria
-Bacteria in the colon feed on waste and produce Vitamin B and K, which are then absorbed into the blood
-Bacteria in the digestive system break down food
-Beneficial bacteria prevent the growth of disease-causing bacteria (pathogens) and fungi
What is a balanced diet?
Contains all the necessary food types in the correct proportions
What factors affect the amount of food a person requires?
-Age
-Activity levels
-Gender
-Health
What does a food pyramid suggest?
Suggests number of servings per day of each of the four main food groups
What are the number of servings needed for each food group?
Milk, cheese and yoghurt: 2
Meat, fish and poultry: 4
Fruit and vegetables: 4+
Cereals, bread and potatoes: 6+
Success criteria of a close-up diagram of the stomach
-Oesophagus
-Stomach
-Liver
-Gallbladder
-Bile duct
-Duodenum
-Pancreas
-Pancreatic duct
Success criteria of a diagram of the digestive system?
-Buccal cavity
-Salivary glands
-epiglottis
-Oesophagus
-Stomach
-Liver
-Pancreatic duct
-Bile duct
-Gallbladder
-Duodenum
-Ileum
-Small intestine
-Large intestine (3 colons, caecum, appendix)
-Rectum
-Anus
