Nutrition Flashcards
Nutrition
the way in which living things obtain and use their food
Autotrophs
make their own food
what do autotrophs make their own food from?
simple molecules
1 example of an autotroph
green plants make food during photosynthesis
heterotrophs
cannot make their own food and must get it from their environment
3 types of heterotrophs
carnivores
herbivores
omnivores
herbivores
animals that only eat plants
2 examples of herbivores
cows
horses
carnivores
animals that eat other animals (flesh eaters
2 examples of carnivores
fox
cat
omnivores
animals that eat plants and animals
2 examples of omnivores
badger
bear
4 stages of human nutrition
ingestion
digestion
absorption
egestion
other stage of human nutrition
assimilation
ingestion
taking in of food (into the mouth)
digestion
breakdown of food into small soluble molecules so that they can be absorbed and transported
absorption
soluble products of digestion pass through the cells in the gut lining into the blood and lymph systems
egestion
unabsorbed, undigested material eg.fibre is removed through the anus
assimilation
the absorbed food is used to make new molecules or for the release of energy
2 names for the human digestion system
alimentary canal
gut
2 types of digestion in the gut
chemical and mechanical
3 times mechanical digestion can be seen in the alimentary canal
teeth
gut muscles
bile salts
explain how the teeth preform mechanical digestion
teeth cut and chew food
explain how the gut muscles preform mechanical digestion
they contractions of the gut muscles churn and mix food with gut secretions
explain how the bile salts preform mechanical digestion
they emulsify lipids
what is the function of mechanical or physical digestion
food is made into smaller pieces for a larger surface area for the chemical digestion
explain chemical digestion
food is made into smaller pieces by enzymes
explain chemical digestion
cells in the lining of the gut and glands associated with the gut, secrete juices containing mucus and digestive enzymes onto food as it moves along
the buccal cavity
oral cavity//mouth//area under nose
pH of the buccal cavity
pH 7
what mainly occurs in the buccal cavity
food is mechanically broken down by the teeth
3/4 types of teeth
incisors
canines
pre-molars and molars
function of incisors
front teeth, flat sharp edges for cutting
function of canines
eye teeth. pointed crowns for tearing
function of pre-molars and molars
side and back teeth with projections or cusps for chewing and grinding
first set of teeth a human has
milk teeth
how many permanent teeth is normal for a human adult
32
how many incisors
8
how many canines
4
how many premolars
8
how many molars
12
what is the dental formula (just understand)
the number and position of each type of tooth in the upper and lower jaws in ONE side of the mouth
human dental formula
I22 C11 P22 M33
what is the correlation between dentition and diet
the number and type of teeth present differs from one mammal to another according to the diet of the mammal
teeth of carnivores
long, sharply-pointed canines for tearing flesh
teeth of herbivores
broad ridged premolars and molars for grinding tough plant material
teeth of omnivores
a full set of teeth without any one type being modified
Chemical digestion in the mouth
food is mixed with saliva secreted by the salivary glanda
saliva consists of (3)
water
mucus
salivary amylase
function of water and mucus in saliva
to lubricate the food
function of salivary amylase in saliva
enzyme that breaks down starch to maltose
what happens to food before it is swallowed
the food is shaped into a ball or ‘bolus’ by the tongue
what does it mean to swallow
it is passed through the pharynx into the oesophagus
what does the epiglottis do during swallowing
it closes over the entrance to the trachea and prevents food from going the ‘wrong way’
what is the oesophagus
a narrow muscular tube that carries food from the pharynx to the stomach
how is food moved in the oesophagus
food is moved by waves of muscular contraction called peristalsis
what is the stomach?
a j-shaped muscular bag in the abdominal cavity
mechanical digestion in the stomach
food is churned into a semi-liquid state called chyme by the contraction of the thick muscle wall
chemical digestion in the stomach
food is acted on by gastric juice secreted by the gastric glands in the stomach lining
3 components of gastric juice
Mucus
HCl
Enzyme (pepsin)
function of mucus in the stomach
protects from self - digestion and lubricates (moistens) the food
function of HCl in the stomach 3
provides the optimal pH for pepsin
it sterilised the food
it hydrolyses (splits) starch
pH of stomach
2
function of enzyme in the stomach
pepsin converts protein to peptides
3 other things that occur in the stomach
food is heated to suitable temp for enzyme
absorption of water, glucose, salts and alcohol
food stored temporarily
how does food pass from the stomach to the duodenum
through the relaxed pyloric sphincter
2 parts of the small intestine
duodenum and ileum
pH of small intestine
7-9
3 things that occur in the small intestine
food is:moved along
digested
absorbed
what is the duodenum
the first part of the small intestine and the main area of digestion
3 places from which the duodenum receives secretions
liver
pancreas
lining of small intestine
what does the liver produce
bile
what is bile
a yellow green alkaline fluid
where is bile stored
the gall bladder
what does bile consist of
bile salts (alkaline) and bile pigments
2 functions of bile
to emulsify fats
to neutralise the acid food coming from the stomach
what does it mean to emulsify fats
to break them down into small droplets to increase their surface area
what does the pancreas produce?
pancreatic juice
where does the pancreatic juice enter the doudenum?
via the pancreatic duct
3 things that pancreatic juice consists of
water, alkaline salts and enzymes
function of alkaline salts in pancreatic juice
neutralise acid coming from the stomach
function of enzymes salts in pancreatic juice
amylase changes starch to maltose
lipase changes lipids into fatty acids and glycerol
what does the lining of the small intestine produce?
intestinal juices
4 things that intestinal juice consists of
water mucus salts and enzymes
which enzymes are in intestinal juice
maltase and lipase
what does maltase do?
converts maltose to glucose
how is food kept moving in the small intestine
through peristalsis ( waves of muscle contraction )
chyle
a watery emulsion that the food is converted into in the small intestine
end products of digestion
glucose, amino acids, fatty acids, glycerol
explain aborption of digested food
the end products of digestion and vitamins and minerals pass through membranes in the ileum into the blood and lymph systems by diffusion
3 ways in which the ileum is adapted for absorption
it is a very long tube with finger-like villi to give a larger surface area
the villus wall is very thin to allow rapid movement of food through it into blood and lymph vessels
it has a large supply of blood and lymph vessels (lacteals) to absorb and carry away the products of digestion
2 ways in which food can be absorbed
into the blood capillaries and go into the hepatic portal vein
absorbed into lymph lacteals
which foods are absorbed into the blood capillaries and go into the hepatic portal vein
glucose amino acids vitamins minerals water
which foods are absorbed into lymph lacteals
fatty acids
glycerol
where do the foods go from the hepatic portal vein
to the liver
where do the foods go from the lymph lacteals
to the lymph system and then to the blood system
the large intestine consists of (4)
caecum
appendix
colon
rectum
function of colon and appendix
no known function in man
in herbivores they house cellulose-digesting bacteria (symbiosis)
3 functions of the colon
reabsorbs water (osmosis)
absorbs minerals and vitamins (diffusion and AT)
forms faeces
faeces
semi-solid waste
where is symbiotic bacteria found?
in the large intestine
function of the bacteria in the gut 3
produce vitamins B and K, defend against pathogenic bacteria and digest some food
5 components of faeces
undigested food, bile pigments, salts, bacteria, dead cells
symbiosis
relationship between 2 different species that involves benefit
function of the rectum
faeces is stored here before being egested via the anus
egestion
removal of undigested or unabsorbed material
largest internal organ of the body
the liver
where does the liver lie?
below the diaphragm on the right side of the stomacj
cells of liver
have a large number of mitochondria
3 blood vessels moving to and from the liver
hepatic artery
hepatic vein
hepatic portal vein
hepatic artery
brings blood (+O2) from the aorta to the liver
hepatic vein
takes blood from the liver to the inferior vena cava
hepatic portal vein
brings blood (+digested food) from the gut to the liver
main function of the liver
regulates the nutrients in blood
2 ways in which the liver regulates the nutrients in blood
it removes excess glucose and stores it as glycogen
it removes excess amino acids and breaks them down forming urea (deamination)
some other functions of the liver
breakdown of red blood cells makes bile stores iron stores vitamins ADEK makes plasma proteins makes cholesterol produces heat detoxification of blood
1 medical disorder of the digestive system
appendicitis
symptoms of appendicitis
severe pain in the lower right part of the abdomen
nausea and vomiting
high temperature
cause of appendicitis
bacteria cause inflammation. the appendix becomes swollen and may burst
prevention of appendicitis
unknown
balanced diet
a diet with the correct amount of each type of food
6 components of a balanced diet
lipids, protein, carbohydrates, vitamins, minerals and water
amount of food needed is affected by
age sex and activity
fibre in the diet
roughage
where does fibre come from
in the form of cellulose found in the cell walls of plants
can humans digest cellulose?
no
what happens to cellulose in the gut?
it absorbs and holds water
what is the advantage of of the cellulose holding the water in the gut?
it increases the volume of waste matter in the large intestine
larger volume of waste matter=
stimulates peristalsis and speeds up movement of waste matter in the intestine which can prevent constipation
good sources of fibre
fruit
vegetables
wholemeal bread
cereals
advantage of having a digestive system
all food is broken down in specialised parts of the body so it can be absorbed into the blood and lymph to go to all cells of the body
what does it mean for our cells that we have one big digestive system?
that all other cells in the body don’t need to have a range of digestive enzymes
