Chapter 7 - Human Nutrition Flashcards
Define diet
the food an animal eats in one day
What are the 6 types of nutrients a human needs in their diet?
- carbohydrates
- proteins
- fats
- vitamins
- minerals
- water
How do we know the amount of food we’re supposed to consume?
gender, age, occupation, etc.
What are carbohydrates used for?
energy
What elements do carbohydrates include?
starch and sugar
Fats and oils are…
lipids
What are fats and oils needed for?
energy and to make cell membranes
Why do we store excess fat and oil under the skin?
to act as an insulator and reduce heat loss
Why do fats and oils form around organs?
to physically protect them
Give 5 examples of products that contain lipids
- oil
- oily fish
- meat
- eggs
- dairy products
What are proteins needed for?
- build new cells
- growth
- energy incase in stravation
What are proteins made of?
amino acids
What other proteins in the body might need to be made?
- haemoglobin
- insulin
- antibodies (help destroy pathogens)
Give 5 examples of proteins
- nuts
- seeds
- meat
- fish
- eggs
- dairy
- peas
- beans
What are vitamins?
organic substances needed in tiny amounts
What happens if we don’t have enough vitamins?
we can get deficiency diseases
What foods contain Vitamin C?
citrus foods and raw vegetables
Why is Vitamin C needed?
to make strechy protein collagen
What deficiency disease can be obtained if an animal lacks Vitamin C?
scurvy
What foods contain Vitamin D?
- butter
- egg yolk
Why is Vitamin D needed?
helps calcium be absorbed for bones and teeth
What deficiency disease can be obtained if an animal lacks Vitamin D?
rickets
Where does most of our Vitamin D come from?
from sunlight that falls on our skin
What are the 2 characteristics of minerals?
- inorganic substances
- only need small amounts in our diet
What foods contain calcium?
dairy products and bread
Why is calcium needed?
bones / teeth and blood clotting
What deficiency disease can be obtained from lack of calcium?
brittle bones, poor blood clotting
What foods contain iron?
red meat, egg yolks, dark vegetables
What is iron used for?
- to make haemoglobin red
What deficiency disease can be obtained from lack of iron?
anaemica
What are the 2 characteristics of fibre?
- human cannot digest it
- all plant foods have fibre due to their cellulose walls
What foods contain fibre?
cereal grains, bread, brown rice
Define parastalsis
rhythmic muscular contractions that move through food through digestive system
How many grams of fibre should be included in our diet based on the European safety authority?
25g
What are the 5 characteristics of water?
- important solvent in cytoplasm
- spaces between our cells are also a watery liquid
- plasma is mostly water
- water is the solvent for enzymes and nutrients in the digestive system
- water is needed to get rid of waste products
What is the alimentary canal?
the group of organs that are all connected by a tube where the food passes through.
What two organs are part of the digestive system but not part of the alimentary canal?
the liver and the pancreas
What are the 5 steps that occur throughout the alimentary canal whilst in digestion?
- ingestion
- digestion
- absorption
- assimilation
- egestion
Describe ingestion
taking food and drink into the mouth using the lips, teeth and tongue
Describe digestion
physical: large pieces of food broken down through mechanical means
chemical: large molecules are broken down by enzymes
Describe absorption
the movement of small molecules and mineral ions through the walls of the intestine into the blood
Describe assimilation
nutrients are absorbed by individual cells and used for energy to make new substances
Describe egestion
the material that we cannot digest, remains in our intestines and eventually is passed out as faeces
What are 3 characteristics of the alimentary canal?
- long tube (mouth - anus)
- wall has muscles that contract/relax to move food along (peristalsis)
- canal lubricated with mucus (goblet cells)
What are the sphincter muscles?
muscles that close the alimentary canal in certain places
Why do the teeth grind food?
to increase the surface area of the food
How does the tongue help food to be swallowed?
the tongue mixes food with saliva to form a bolus
What are the 3 characteristics of salivary glands?
- water dissolves substances in food to form taste
- mucus helps food bind in bolus
- amylase begins to digest starch
What are the 2 characteristics of the oesophagus?
- takes food to stomach
- hole in center (lumen)
What are the 7 characteristics of the stomach?
- strong muscular walls which contract to mix food with saliva and enzymes
- goblet cells secrete mucus
- cells produce enzymes that break down proteins
- cells produce HCl
- pH 2
- optimum pH for stomach enzymes
- can store food for 1-2 hours
What is the duodenum?
the first part of the small intestine
What is the ileum?
the last part of the small intestine (closest to colon)
What are the 2 characteristics of the small intestine?
- 5m long
- “Small” because it’s narrow
What does the duodenum do?
pancreatic juice flows through the pancreatic duct into the duodenum. it’s filled with many different enzymes to help with chemical digestion in this part of the canal
What does the Ileum do?
Absorbs digested nutrients into blood
What are the 3 characteristics of the large intestine?
- 1.5 m
- final part of alimentary canal
- made up of colon and rectum
What does the colon do?
absorbs water left in food
What does the rectum store?
undigested food
What are the 4 characteristics of the pancreas and the liver?
- not part of the alimentary canal
- pancreas secretes pancreatic juice into intestine
- liver creates bile
- bile is produced in liver and stored in the gall bladder
What does bile do?
- helps neutralise stomach acid
- emulsifies fats into small droplets
What is physical digestion?
large pieces of food are broken down into smaller pieces. this is done by teeth & churning movements of stomach.
chemical components of food are unchanged
What is chemical digestion?
large molecules are broken down into smaller ones. involves chemical reactions catalysed by enzymes
smaller molecules are soluble in water, easier to absorb into the blood
Why are vitamins, minerals and water not digested?
because their molecules are already small enough to be absorbed into the blood
What are the 4 characteristics of teeth?
- bites off pieces of food
- then they chop, crush & grind pieces into smaller ones
- gives food larger surface area
- helps soluble molecules or ions dissolve in watery saliva
What are the 7 parts of the tooth?
- enamel
- dentine
- pulp
- gum
- jawbone
- fibres that attach tooth to jawbone
- cement
What are the 2 characteristics of the enamel?
- hard to break / chip
- able to be dissolved by acids
What do bacterias feed on?
sweet food
What are the 3 characteristics of the dentine?
- similar to bone
- hard
- has a channel that contains cytoplasm
What are the 2 characteristics of the cement?
- has fibres growing out of it
- attaches tooth to jawbone but still allows it to move
go memorise the teeth table in your notebook
ok
During digestion, at what temperature and pH do enzymes work best?
temperature: 37º-38º
pH: stomach - 2 duodenum - 7
In what 2 places is amylase secreted and where does it act?
salivary glands (acts in mouth) and pancreas (acts in duodenum)
In what 2 places is protease secreted and where does it act?
walls of stomach (acts in stomach)
and pancreas (acts in duodenum)
In what place is lipase secreted and where does it act?
pancreas (duodenum)
What are the 2 characteristics of amylase?
- secreted into mouth and duodenum
- breaks starch into maltose
What are the 3 characteristics of maltase?
- 1 maltose = 2 glucose
- maltose = smaller than starch but too big to be absorbed
- secreted by cells living in small intestine
What is the tissue of the lining of the small intestine called?
epithelium
What are the 3 characteristics of pepsin?
- pepsin is protease in the stomach
- pepsin is secreted from the stomach walls in gastric juice
- pH 2
What is gastric juice?
a liquid that contains HCl to kill harmful microorganisms in food
What are the 3 characteristics of trypsin?
- created in the pancreas and secreted into the duodenum
- all proteases break proteins down
- pH 7
Why are proteins broken down?
because amino acids are small enough to be absorbed
What has to happen in order for trypsin to work?
the acidic contents of stomach must be neutralised by alkaline substances in bile and pancreatic juice
What are the 4 characteristics of bile?
- acts like detergent (helps break down fats)
- breaks down large droplets of fat into smaller ones
- INCRREASES FAT’S SURFACE AREA
- Physical digestion
what is a mix of tiny floating droplets of oil called?
an emulsion
Why is it important for fats to be broken down into smaller pieces?
to increase their surface area
Define villi
small finger-like projections that line the inner surface of the small intestine, increasing its surface area
Approximately, how long is one villus?
1 mm
Where does maltase act?
in the microvilli
How does maltase act?
maltase breaks down maltose into glucose
What is absorbed by the microvilli? (7)
- water
- glucose
- fatty acids
- glycerol
- mineral ions
- vitamins
- amino acids
Where do nutrient ago after passing through the villi / microvilli?
the blood capillaries
What is the name of the vein in which all blood capillaries join?
hepatic portal vein
What is the lacteal?
small vessels that absorb glycerol and fatty acids in the small intestine. Their contents are emptied into the blood eventually
