NUTRITION -2
The ruminant digestive system
A ruminant is an animal that chews
food, swallows it then returns it to the mouth later for further chewing. This
is called chewing cud. Examples of ruminants are cows, goats, sheep,
antelopes and giraffes.
The digestive system of a ruminant
is different from that of a human being. Ruminants have a more elaborate system
to enable cellulose digestion.
The stomach of a ruminant has four
chambers: rumen, reticulum, omasum and abomasum.
When a ruminant first chews and
swallows a mouthful of plant matter, the food enters the rumen. Bacteria in the
rumen immediately start digesting the cellulose present in the material.
Chewing cud softens and helps down plant fibres, making them more access to
digestion by the bacteria. When the food in the rumen, it is coarse and very
green. The food then regurgitated and chewed again. It passes the reticulum.
The reticulum has a 'honeycomb" appearance. In the reticulum, the food is
mixed thoroughly with water. The food coarse, more watery, less green and very
small compared to the food in the rumen.
The food is regurgitated, chewed
again and passed to the omasum. The abomasum has longitudinal folds like the
leaves of a book. The folds help to remove water from the food. The food
in the omasum is in form of fine particle and has very little water.
The abomasum
is the ruminant's stomach. The abomasum has gastric
acid facilitates the digestion of proteins. It also has microorganisms that may
have spilled over the rumen.
OUTER SIDE OF RUMINANT STOMACH
Differences
between the ruminant System and the human digestive
system are:
- Ruminant digestive system has four chambers. Human
beings have one stomach chamber.
- Ruminants have no upper incisors. Instead, they have a
horny pad. This helps in the chewing of food. They also have a gap on the
lower jaw called diastema. –humans have upper incisors and no
diastema. Ruminants chew cud. They regurgitate what they had swallowed and
chew it again. Human beings do not chew cud.
- Ruminant's digestive system has organisms(bacteria)
that help to digest fibre and synthesize vitamin B. Human beings cannot
digest fibre.
Diseases and disorders of the digestive system
This includes diseases and disorders
that affect; the oesphagus, the stomach and the
large intestines. Examples include
dental caries heartburn, stomach ulcers, constipation flatulence and cancer.
1. ULCERS
- These occur as a result of the action of enzymes and
acid on the epithelial membrane lining of the stomach and duodenum walls.
The mucus coating can be broken by bacteria called Hericobacter pylori
Cause
- Ulcers can be caused by stress which stimulates acid
production
- Ulcers can also be inherited.
- Certain medication like aspirin
- Smoking and taking alcohol
- Caffeine
Sign
and symptoms of ulcers
- Burning pain in stomach or the middle of thorax
- Nausea and vomiting
- Tiredness and weakness
- Blood in vomiting or stool (a symptom of breeding
ulcer)
CONTROL OF ULCERS
Ulcers can
be controlled as follows
1) Have
stress reduction programs
2)
Eliminate smoking and drinking alcohol
3)
Changing diet and taking meals on time
- The
ulcers can be corrected or reduced by the following treatment
1.
Drinking milk
2. Taking
magnesium trisilicate tablet
3. Surgery
which include
- Cutting
the vestigial part
-
Gastrectomy removal of the duodenum and the stomach.
2. CONSTIPATION
- This is the frequent passage of
hard faeces
Constipation is caused by the
following:
(i) Abnormally slow movement of
faeces matter through colon. As a result maximum absorption of water takes
place leaving very dry hard faeces.
(ii) A diet low in fibre such as
roughages
(iii) Failure of the sensory cells
to signal the presence of faecial matter in rectum.
CONTROL
Constipation can be controlled by
(i) Eating high fibre rich food.
(ii) Drinking a lot of water.
3. HEART BURNS
This is the burning sensation along
the alimentary canal or in the chest cavity as a result of accumulation of too
much acid in the stomach.
- An individual with this problem feels uncomfortable all
the time
- Prolonged heart burn can lead to oesophagus ulcers
CONTROL
Heart burn can be reduced by
drinking milk or taking tablets which neutralize the acid of the chyme.
4. FLATULENCE
This is a condition caused by
excessive gas in the digestive track it causes pain and embarrassment to many
individuals.
- The intestinal gas such as oxygen and nitrogen are
gulped in while breathing and at the same time eating
- Other gases such as methane, carbon dioxide and
hydrogen are produced from fermented undigested food
- The gases in the intestine can be minimized by
(i) Eating
slowly
(ii) Avoid
milk if you are lactose intolerant
(iii) Not
eating gas – inducing food such as beans, cabbage, onions
(iv) Using
antacids
- DENTAL CARIES
This is commonly referred to as
tooth decay. It occurs when bacteria destroy the outer part of the tooth.
Development of dental caries
There are always bacteria present in
the mouth. The bacteria combine with acid, saliva and remains of food to form plaque.
Plaque is the sticky substance often found between teeth. Plaque begins to
form within 20 minutes after we eat. The bacteria in plaque convert the remains
of food (especially sugar and starch) into acids.
The acid dissolves the enamel in the
tooth, forming a cavity. If this cavity is left untreated, it reaches
the pulp cavity and nerve endings inside the tooth causing an infection.
This disease is caused by a number
of factors including:
(i) Lack of hard food
(ii) Too much sweet food
- Sweet food tends to encourage growth of bacteria
(iii)Lack
of calcium in the diet
(iv)Lack
of vitamin D
(v)
General ill health
- CANCER
- Cancer is a disease which affects the digestive tract
include
- Cancer of oesophagus
- Cancer of the colon
- There are various causative agents of cancer, Their common ones include
i)
Mutation of genes
ii) Cancer
inducing foods we eat. They affect the colon when they come in contact over a
long direction of time
TREATMENT
- It has not been up to date easy to treat or prevent
cancer. The following methods are applied in treating it.
1)
Chemotherapy – During treatment to supplement surgery
2)
Radiation – Bombardment using radioactive particles to eliminate the cancerous
cells
3) Surgery
– Removal of all cancerous cells
NOTE: The outlined treatment are not 100% perfects, they will
affect other cells or induce other cells to become cancerous
CONTROL
Taking the
fibre food in the food to come into contact with the cells leaving the colon
wall
NUTRITION
IN PLANTS
AUTOTROPHISM
This is
the mode of nutrition used by green plants to manufacture their own food.
- The process is used by green plants to manufacture
their food is known as photosynthesis.
Definition
– photosynthesis is the process in which green plants manufacture complex food
substances from simple inorganic substances such as carbon dioxide and water in
the process of sunlight and chlorophyll
- This process of photosynthesis occurs in the green
parts of the plants mostly in leaves
STRUCTURE OF THE LEAF
A) EXTERNAL PARTS OF THE LEAF
1) Petiole – attaches the leaf to
stem or branch.
2) Veins – Transport materials
within the leaf
3) Midrib – gives rise to veins.
Transport materials to the leaf
4) Lamina- photosynthesis takes
place in it.
B) INTERNAL PARTS OF THE LEAF
The internal parts of the leaf
consist of
1) Cuticle
2) Epidermis
3) Guard cell
4) Palisade layer
5) Spongy mesophyll layer
6) Leaf veins
7) Chloroplast
Diagram showing the internal parts
of a leaf
FUNCTION OF THE INTERNAL PARTS OF LEAF
a) CUTILE – This is a thin
wax transparent and water proof
- It is found on both sides of the leaf
Functions
(i) Reduce excessive water loss
(ii) Protects inner tissue from damage
(iii) Prevents entry of pathogens
b) EPIDERMIS – This is a thin layer found on both sides
Functions
i) secretes (makes) the cuticle
ii) Protects inner tissue from
damage
c) GUARD CELLS
Are bean shaped epidermal cells
mostly found on the lower surface.
Functions
i) Control opening and closing of
stomata
ii) Control water loss
iii) Allow gaseous exchange
iv) Contain chloroplasts with
chlorophyll used to trap sunlight for the process of photosynthesis.
d) PALISADE LAYER
This is the layer between the upper
epidermis and the spongy mesophyll layer
- It is made up of palisade cells
Functions - trap sunlight by using chlorophyll for the process of
photosynthesis
e) SPONGY MESOPHYLL LAYER
This is found between the palisade
layer and the lower epidermis
Function
i) Used for gaseous exchange
ii) Photosynthesis takes place in it
f) LEAF VEINS
Consist of both xylem and phloem
Functions:
- Xylem transport water and mineral salts from the root
to the rest parts of the plants.
- ii) Phloem transport manufactured food from the leaves
to the rest parts of the plant.
g) CHLOROPLAST
These are disc shaped organelles
that contain chlorophyll
Functions:
- Chlorophyll absorbs (traps) sunlight for photosynthesis
REQUIREMENTS AND CONDITIONS
NECESSARY FOR PHOTOSYNTHESIS
The raw materials of photosynthesis
are:
a) Carbon dioxide
b) Water
- Carbon dioxide is obtained from the atmosphere and
water is absorbed by the roots from the soil.
- The conditions necessary for photosynthesis to take
place are
(i)
Chlorophyll
(ii)
Sunlight
- Chlorophyll is used to absorb light energy needed
during photosynthesis and sunlight (solar energy) is converted to chemical
energy (ATP) needed by all living organisms
PROCESS OF PHOTOSYNTHESIS
The process of photosynthesis occurs
in two stages which are:
(i) The light stage.
(ii) The dark stage.
THE LIGHT STAGE
- It occurs in the chloroplasts
- The chlorophyll absorbs light energy from the sun
- The light energy is used to split the water molecules
to oxygen and hydrogen
The
process is known as photosynthesis
Oxygen is released to the atmosphere while some is used in
respiration
- Hydrogen enters the dark reactions
- Some of the solar energy absorbed by the chlorophyll
molecules is used in the formation of energy rich compound known as
Adenosine triphosphate (ATP) which later is used in the dark stage of
photosynthesis
THE
DARK STAGE
- It occurs in the stomata and it doesn’t need a light
- Carbon – dioxide combines with hydrogen to form sugar
such as glucose
- This process is called carbon dioxide fixation
- This process requires energy (ATP) and enzymes i.e.
END PRODUCTS OF PHOTOSYNTHESIS
The end products of photosynthesis
are:
i) Glucose
ii) Oxygen
iii) Water
Glucose – is used in respiration to release energy. Some is stored
as starch or oils during exchange.
Oxygen – Some oxygen is used during respiration while the rest is
released into the atmosphere during exchange.
Water – some water is used in various chemical reactions within
the cells, some water is released to the atmosphere during transpiration
The overall chemical equation
representing the process of photosynthesis
ADAPTATION OF THE LEAF IN THE PROCESS OF PHOTOSYNTHESIS
(i) Cuticle and epidermis are
transparent to allow easy penetration of light
(ii) Presence of stomata on the leaf
allows easy diffusion of carbon dioxide
(iii)The network of veins allows
movement of materials in and out of the leaf
(iv)The air spaces in the spongy
mesophyll layer allow gases to circulate easily.
(v) Presence of large numbers of
chloroplasts in the palisade layer enables maximum sunlight absorption.
(vi) The leaves are well arranged to
avoid overlapping and overshadowing
(vii) Broad and flat lamina allows
maximum absorption of sunlight and carbon dioxide.
FACTORS AFFECTING THE RATE OF PHOTOSYNTHESIS PROCESS
1. LIGHT INTENSITY: A good
quality of light enhances the rate of photosynthesis.
- Very bright light damages the plant due to strong sun rays
- Plants under shade receive poor quality of light
2. CARBON – DIOXIDE
CONCENTRATION: An increase in carbon dioxide concentration results to an
increase in the rate of photosynthesis up to a certain level
- Any further increase in the carbon
dioxide concentration after the maximum point induce the stomata to close and
therefore cutoff the supply of carbon dioxide.
3. TEMPERATURE:
Photosynthesis is controlled by enzymes. Enzymes are affected by changes in
temperature.
- High temperature destroys the
enzymes, very low temperature inactivate them.
- The rate of photosynthesis
increase as the temperature increase up to maximum point i.e. 400c.
4. WATER: Plants require
water for the various chemical reactions of the cells.
-Water is also a raw material for
photosynthesis.
5. MINERAL SALTS: Some
minerals such as magnesium and iron are responsible in the formation of
chlorophyll.
- The availability of these minerals
results in the chlorophyll synthesis and the rate of photosynthesis increases.
6. LEAF AGE: As the leaf ages
chlorophyll breaks down hence the rate of photosynthesis is reduced.
7. PRESENCE OF MANUFACTURED CARBOHYDRATES: This will reduce the rate of
photosynthesis since carbohydrates are product of photosynthesis
IMPORTANCE OF PHOTOSYNTHESIS
(i) Food substance like glucose is
formed. Plants and animals use these food substances.
(ii) Release oxygen in the
atmosphere for respiration of organisms
(iii) Purify the atmosphere by removing
carbon dioxide.
(iv) Light energy is converted into
a form that can be used by all other organisms. This energy is known as ATP.
STORAGE ORGANS
Plants store food for future use
Foods in plants can be stored in:
(a) Leaves e.g. Onions, cabbage
(b) Fruits e.g. Mango, pineapple,
pawpaw
(c) Seeds e.g. Beans, peas, rice,
maize
(d) Stems e.g. Irish potato, ginger,
sugar cane
(e) Roots e.g. Sweet potato,
cassava, carrots
ADVANTAGE OF FOOD STORAGE ORGANS
i) Some organs give rise to new
plants e.g. Seeds, stem, tubes
ii) Permits the survival of plants
over dry seasons.
iii) Some are used as source of food
by man and other animals e.g. Rice, wheat, potatoes etc.
iv) The stored food is used during
germination before the leaves form.
v) Some are used for commercial
purpose by man e.g. Sugar cane
MINERAL REQUIREMENTS IN PLANTS
- The mineral elements required by plants are grouped
into two;
- Macro elements or Macro nutrients
These are
elements required in large quantities by the plants.
They include; manganese, carbon,
calcium, oxygen, phosphorus, sulphur, hydrogen, potassium and nitrogen.
2. Micro element or micro nutrients
These are elements required in
small quantities by the plants.
They include; manganese, zinc,
sodium, boron, chlorine, copper, cobalt and silicon.
NOTE: Nitrogen, iron and magnesium
are used to synthesize carbohydrates
- Lacking of these elements cause yellowing of leaves
- Carbon, Hydrogen and oxygen are used to synthesize
carbohydrates
- Lack of these elements show stunted growth in plants.
FOOD PROCESSING, PRESERVING AND
STORAGE
Food processing: This refers to all the ways in which food is treated in
order to make it edible, appetizing and safe to eat or keep it fresh for a long
time
- Some of the activities involved in food processing are:
(i)
Picking, sorting and washing fruits and vegetables
(ii)
Converting raw material into other products
Examples –
Making cheese from
milk
- Making sugar from sugar cane
FOOD PROCESSING TECHNIQUES
Common food processing techniques
include
i) Removing unwanted outer layers
e.g. peeling potato
ii) Chopping or slicing e.g. Bananas,
mangoes and cassava
iii) Liquefaction e.g. producing
juice by squeezing fruits
iv) Fermentation e.g. making wine
from banana and grapes and beer brewing
v) Cooking e.g. boiling, frying,
steaming or grilling
vi) Deep freezing
vii) Baking
FOOD PRESERVING
This is a method that involve
special methods of food processing that are used to prevent food from getting
spoiled or going bad. These methods include:
1. Canning or bottling; this is used
for getting rid of micro – organisms.
2. Pasteurization and boiling; this
involves using high temperature to kill micro – organisms that cause spoilage
3. Refrigeration – using very low
temperature to slow down the growth of micro – organisms
4. Irradiation – this involves using
radiations to kill micro – organism that might make food go bad.
5. Drying salting, applying honey or
smoking eliminate the moisture that is needed for growth of micro organisms.
6. Adding chemicals such as salt,
sugar and carbon monoxide to prevent physical changes in food.
IMPORTANCE OF FOOD PROCESSING,
PRESERVING AND STORAGE
1) Prevents wastage of food
2) Saves money by preventing
spoilage of food
3) Maintains the quality of food.
4) Prevents growth of micro –
organisms that can cause illness and improves the flavor of food.
5) Removes harmful toxins and micro
– organisms from food
6) Makes food available even when
they are not in season
7) Enables transportation of
delicate and perishable food such as milk and fruits over long distance
TRADITIONAL METHODS OF FOOD
PROCESSING AND PRESERVING
1. CURING: This involves the
addition of substances such as sugar, salt, spices and vinegar to animal foods
e.g. Meat and fish.
- Curing binds or removes water
making it unsuitable for the growth of micro – organism
- It also improves the taste of
food. Example sausage and canned beef are made by curing meat.
2. DRYING IN THE SUN
The food is left in the sun for long
periods of time in order to reduce its moisture content.
- Removing the amount of water in the food discourage the
growth of micro – organism This method is used to reserve rice, maize,
cloves, bananas, beans, peas, meat, fish, cassava and green vegetables.
NOTE:
Dried grain or cassava can be pounded or ground into flour and dry cloves are
used for making spices.
3. SMOKING
Smoke reduce the moisture content of
food to prevent the growth of micro – organisms
Example: Grains, meat and fish can
be dried slowly over a smoking wood fire.
4. COOKING: This includes
boiling, steaming, baking in hot ash, grilling and roasting.
- These processes help to soften
food, improve flavor and preserve food. Examples: potatoes, banana, and maize
can be boiled before being dried
- Meat can be grilled or deep fried.
5. SALTING: Salt removes
water from the food and kills micro – organisms that would otherwise spoil the
food.
6. FERMENTATION
Fermentation is the conversion of
carbohydrates such as sugars into acids and alcohol
Fermentation can occur naturally or
can be induced
Example: Milk can be fermented into
yoghurt by keeping in a container for some time.
Picking foods such as cucumbers and
mangoes can be fermented by putting them in salty water for some time, bacteria
produce lactic acid that gives the food its distinctive flavor and helps to
preserve it.
MODERN METHODS OF FOOD PRESERVATION
AND PROCESSING
1. PASTEURIZATION: This is the
method of heating food to very high temperature for a short while in order to
kill micro – organism that can cause food spoilage
Pasteurizations maintain the
nutrients content and flavor of food. Example: Food which can be pasteurized is
milk and fruit juice
2. LIQUEFICATION; this is the making
of liquids from solid food
- It is mostly applied to fruits
where by juice is made out of them.
- The juice is then pasteurized and
post into cans or containers.
3. CANNING AND BOTTLING
This is the method where by food is
preserved by heating it in air tight vacuum – sealed bottles or cans.
- First the container is filled with food then the air is
pumped out to form a vacuum.
- The container is sealed and heated to kill micro –
organisms and enzymes fruits and fruits juices, beef, fish and baked
beans.
NOTE:
Bottled and canned foods can be kept for months or even years.
4. USING ADDITIVES – This is the
addition of chemicals such as sodium benzoate, sodium chloride and vinegar to
slow down the growth of micro – organisms. Examples the food can be preserved
by this process are fish and meat.
5. DRYING OR DEHYDRATION: This is
where food is dried by using either hot blasts of air from vacuum dryer or a
freezer (freeze drying).
- After drying, the food is then
sealed in moisture proof containers
6. IRRADIATION – This is the use of
ray’s energy to stop growth of micro – organism in stored food stuff.
- This makes food last longer
- Also prevents spoiling.
Examples: the foods that can be
preserved by this method are onions, beans and potatoes
FOOD STORAGE
Food storage is a method used to
keep reserves of food for future use
- Food storage can be done on a small side at the family
level. Examples in the food storage, or on a large scale for populations.
Example in government sides for grains
TRADITIONAL METHODS OF FOOD STORAGE
1) Storage in granaries and pits
- Dry grains are stored in granaries
which are usually raised above the ground.
The gains are sometimes mixed with
neem leaf ash or groundnuts to further prevent attack by micro – organisms.
- Granaries keep grains safe from insects, rodents and
birds
- Harvested yams, potatoes and cassava can be stored in
large the ground after drying.
2) Storage in pots and tins
- Preserved foods such as flour,
dried vegetables and cassava can be in large dry puts or tightly covered for
future use.
- Foods can be stored for months by
using this method.
ADVANTAGE OF TRADITIONAL METHODS OF
FOOD PROCESSING, PRESERVATION STORAGE
i) They are simple and can be done
by most people
ii) They use locally available
materials and simple technology, the keeping costs low.
iii) No harmful chemicals are added
to the food.
iv) Curing and smoking add a
distinctive flavor to the food
v) Most methods do not destroy
nutrients
DISADVANTAGES OF TRADITIONAL METHODS
OF FOOD STORAGE, PROCESSING AND PRESERVATION
i) Food can be preserved and stored
for only limited periods of time
ii) Traditional method is difficult
to do on a large scale.Traditional methods are highly limited in the variety of
foods that can be processed, preserved and stored
MODERN METHODS OF FOOD STORAGE
1. Refrigeration
- This is the temporary storage of
food at temperature of up to 40c in order to slow down the growth of
micro – organism
- Refrigeration can be done in
refrigerators or cold rooms
Example: The foods that can be
refrigerated are milk, fresh fruit, fresh vegetable, juice and bottler.
2. Freezing: This is the strong food at very low temperature i.e. below
-100c in order to stop the growth of micro – organisms
Food is frozen in freezers. Example
the foods that can be frozen are: poultry, fish and meat.
ADVANTAGES OF MODERN METHODS OF FOOD
PROCESSING, PRESERVATION AND STORAGE
(i). Food can last for many months
or even years
(ii). Modern methods can process,
preserve and store a large variety of foods.
(iii). The advanced technology used
is fast and can handle large quantities of food
DISADVANTAGES OF MODERN METHOD OF
FOOD PROCESSING, PRESERVATION AND STORAGE
- The chemicals used can be harmful if eaten in excess.
- These methods can only be used in a certain area.
Example – refrigeration and freezing require electricity.
- The process used for example radiation; canning and
pasteurizing require special skills.
- Sometimes nutrients are lost thus lowering the
nutritional value of food.
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