2. Introduction
• Nutrition - process by which
organism obtain energy & nutrient
from food
• Need for growth, maintenance &
repair of damaged tissues
• Nutrients – substances required for
nourishment of an organism
• Types of nutrition is based on how an
organism feed for their survival
4. Autotrophs
• Autos : self trophos : feed
• Organism which practise autotrophic
nutrition
• Synthesis complex organic compound
(food) by their own
• Using inorganic substances with the help
of light/chemical energy
• By photosynthesis or chemosynthesis
5. Autotrophs
Photosynthesis
Photos : light
- Green plants or photoautotroph
- Produce organic molecules (food)
from CO2 & H2O
- Light as a source of energy
Chemosynthesis
Chemo : chemical
- practise by certain type of bacteria
or can be called as chemoautotroph
- Produce organic compounds (food)
without the help of light
- Will oxides inorganic substances such
as (hydrogen sulphide or ammonia)
to obtain energy
6.
7. Heterotrophs
• Heteros : other
• Cannot synthesis their own nutrition
• Organism which practise heterotrophic
nutrition
• Obtains energy through the intake &
digestion of organic substances (plant &
animal tissues)
• May practise i-holozoic nutrition
ii-saprophytism
iii-parasitism
8. i. Holozoic nutrition
• Holo : like zoon : animal
• Feed by ingesting solid organic
matter & digest then absorbed it
• Eg: human , all animal & carnivorous
plant (capturing & ingesting small
insects)
10. ii. Saprophytism
• The organism are
called as
saprophytes, feed on
dead & decaying
organic matter
• Such as bacteria &
fungi
• Digest food
externally b4 absorb
nutrient
11. iii. Parasitism
• Close association
between 2 organism
• Parasite – obtains
nutrient (readily
digested food) by living
on or in the body of
other living organism,
host
• Eg : fleas & lice,
bacteria, fungi, worms
(human alimentary canal)
A cluster of nematodes, the
roundworm of dogs,
Toxocara canis
12. Match the following with correct
answer
• Feed on dead & decaying organic
matter
• Feed by ingesting solid organic
matter & digest then absorbed
it
• Obtains nutrient by living on or
in the body of host
• Obtains energy through the
intake & digestion of organic
substances (plant & animal
tissues)
• Hetetrophs
• Holozoic nutrition
• Saprophytism
• Parasitism
13. The Importance of A Balanced Diet
Balanced diet :
Diet that has all the nutrients in the right amount.
Why it is important:
Obtained enough energy
Maintain a healthy
body
Prevent infection of
disease
Quantity of nutrients depends on
Age
Condition of
Health
Type of
Work
Sex
Physicals
activities
Environment
Body Size
Climate
14. Balanced diet
is a utmost importance to health
• The necessity for a balanced diet in food
consumed :
1- Provides energy for all biochemical reaction needed for
living. Mammals & birds need energy to maintain
body temperature
2- Provides the material needed to build cells & tissues for
the growth process
3-To replace damaged & dead cells
* The food in a balanced diet should contain the major nutrients
includes carbohydrates, proteins, lipid, mineral salts, vitamins,
roughage (dietary fibre) & water (7 classes of food)
* These nutrients must be taken in the correct proprotions to meet the
daily requirements of the body
15. Daily energy requirement
• Energy is needed to sustain vital functions – heartbeat,
breathing & maintaining body temperature
• It is generated by the oxidation of molecules obtain from
food during cellular respiration
• Energy content of food – determined by – burning a known
mass of the food in the presence of oxygen in a bomb
calorimeter
• Energy value – the amount of heat generated from the
combustion of 1 gram of food
• Unit – joule per gram (J gˉ¹)
• 4.2 joules of energy are needed to raise the temperature of
1 g of water by 1°C
16. • 3 main energy-providing organic molecules are lipids,
carbohydrates & proteins
• 1 g of lipid – 37.6 kJ of energy (twice than protein &
carbohydrate – almost 18.8 kJ)
• Energy values of proteins = 22.2 kJ gˉ
carbohydrates = 16.7 kJ gˉ¹
17. Nutrient content in food
• Carbohydrates i. starch ( rice, flour, potatoes &
cereals)
ii. sugar (sugar cane – main
sources)
• Proteins meat, fish, egg, milk, cereals
• Lipid animals fat, butter, margarine, egg yolk
• Others are vitamins, mineral, roughage, water
18. Vitamins
• Non-protein organic compounds cannot be
synthesized by our body
• Needed in small quantity
• Cannot be digested & release no energy
• Essential for the maintenance of good health &
efficient metabolism
• Defficiency in specific vitamins- lead to specific
disease
• 2 groups : i. Fat-soluble vitamins
ii. Water-soluble vitamins
19. 2 groups of vitamins
Fat-soluble vitamins
- Can be stored in body fat
- Eg : Vit A, D, E, K
Water-soluble vitamins
- Can’t be stored in body
- Have to be supplied in daily diet
constantly
- Eg : Vit B & C
- Vit B complex – coenzyme ;
work together with enzyme
Vitamin E
Vitamin D
Vitamin K Vitamin A Vitamin B Vitamin A
20. Sources of Vitamins, their functions and
Deficiency effects
Vitamins Source Function Deficiency
effects
A Egg, milk, cod liver oil,
cheese, liver, papaya
- Good vision
- Healthy skin
- Night blindness
- Dry scaly skin
B Egg, milk,liver, yeast and
cereal
- Preserves the
nervous system
- Beriberi
- Pellagra
- Insomnia
C Fruits, tomato, green
vegetable
- Healthy skin
- Absorption of iron
- Anemia
- Unhealthy skin
- Scurvy
D Egg, margarine, fish oil,
milk, cheese
- Absorption of
calcium and
phosphorus
- Strong teeth and
bones
- Rickets
- Tooth decay
E Milk, egg, palm oil,
green vegetable, cereal
- Functions of
reproductive system
- Sterility
K Liver, tomato, green
vegetabe, spinach
- Blood clothing - Difficulty in blood
clothing
21. Minerals
• Simple organic nutrient obtained through the diet (food
or drinks)
• Required in small quantities in the ionic form by the
body
• Do not provide energy
• Vital for the maintenance of good health
• Babies require more calcium & phosphorus compared to
adults for building strong bones and teeth
• Adolescent girls require more iron than adolescent boys
22. Mineral
element
Source Function Deficiency
effect
Calcium Egg yolk,
milk, cheese,
cereal, green
vegetable
- Strong
bones
and teeth
- Blood
clothing
- Rickets
-
Osteoporosis
- Tooth decay
Iron Egg yolk,
meat, liver,
spinach
- Component of
the
hemoglobin.
- Anemia
- Tiredness
Phosphor
us
Egg, milk,
fish, green
vegetable
- Strong teeth
and bones
- Rickets
- Muscles
cramps
- Tooth decay
23. Macrominerals Microminerals
- Required in large quantities
- > than 100 mg per day
- Eg : Magnesium, potassium,
calcium, phosphorus, chlorine,
sodium, sulphur
Phosphorus structural comp of
Calcium bones & teeth
Sodium nerve function & osmotic
Potassium balance between body cell
Chlorine - interstitial fliud
- Required in trace amounts
- < than 20 mg per day
- have very specific functions
- Eg : ferum, iodine, zinc, boron, copper
molybdenum
Ferum production of haemoglobin
Iodine in thyroxine hormone
24. Roughage or dietary fibre
• Dietary fibre – indigestible part of
plant food consists of mainly
cellulose
• Recommended – 25 50g
• Eg : in vegetables, nuts, wholemeal
grains, fruits
• Passes out of the alimentary canal
in the faeces without being
absorbed or assimilated
• Has high holding capacity &
provides bulk to the intestinal
content (in large intestine)
• Deficiency - constipation
25. Water
• 70% of body is water
• Main participant in biochemical reactions
• Requires 2 to 2.5 litres of water daily
• Loss from body by perspiration – skin, evaporation – lungs
(breathing), excretion – kidney (urine or faeces)
• Failure to replace the water lost - dehydration
Food
Drinks Sweat
Urine
Breath
FaecesMade in
body
Water gained
total = 2600 cm³
Water lost total =
2600 cm³
Daily water balance
26. Functions:
Help in the transportation
To soften food
To dissolve waste products
To control the
concentration
To control body
temperature
To give shape to the body
29. Malnutrition
• Unbalanced diet in which certain nutrients are
lacking, in excess, or in wrong proportions
• Protein deficiency - i. Kwashiorkor ; does not
receive sufficient protein in diet – distended
stomach, very thin, suffers from diarrhoea, thin
hair, a swelling of the body due to retention of
fliud in tissues, flaky skin & stunted growth
- ii. Marasmus ; general
wasting of body = protein deficiency + lack of
energy-providing nutrients, very thin & wrinkled
skin, usually occurs in children aged between 9
to 12
31. • Vitamin deficiency :
- Vitamin C deficiency ; Scurvy ; swollen, bleeding gums & tooth loss
- Effects of overdoses of vitamins
Vitamin Effects
C Gastrointestinal upset
A Hair loss, vomiting, bone ache, joint pain,
liver & bone pain
E Kidney damage
D Too much calcium in the blood –interferes
with the functions of muscles & heart
tissues
K Liver damage &anemia
B6 Numb feet & poor cordination
B3 (niacin) Flushed face & hands
Liver damage
32. • Mineral deficiency :
- Shortage of ferum ; anemia
- Limited supply of Vit D, calcium & phosphorus ;
rickets
- Lacking in calcium ; osteoporosis – bones
becomes porous & break easily
33. Excessive intake of :
i) carbohydrates & lipids – obesity
cardiovascular disease / diabetis melitus /
cancer
ii) sugar - diabetis melitus
iii) vitamins A – hair lose, bone & joint paint,
loss of appetite, liver damage
iv) vitamin D – overload of calcium in blood &
calcification of soft tissues
v) sodium – high blood pressure , heart
disease, stroke & (kidney
stones) kidney failure
vi) Protein – gout = uric acid forms crystal in the soft tissues of the
joints.
34. Food Digestion
• Digestion – the process that breaks down
complex food substances to simpler, soluble
molecules small enough to absorb
• Substances required by cells to carry out
metabolic processes are :
= glucose (starch) to generate energy
= amino acids (protein) to synthesise new proteins
= glycerol & fatty acids (lipids) to form plasma
membrane
35. Digestion of carbohydrates, proteins &
lipids
Take place in the alimentary canal :
* A long, muscular tube extend from the mouth to the anus
* Divided into specific regions for different digestive processes take
place
* Receive digestive juices (from accessory glands)
* Food is broken down in stages till dissolved & absorbed
* Indigestible residue expelled through the anus
Digestion breaks down :
A- starch into glucose
B-proteins into amino acid
C-lipids into glycerol & fatty acid
36. Digestion
• Involves physical & chemical processes
i- Physical digestion :
= breaking up of large pieces of food into smaller
pieces by mechanical process
= starts in mouth slicing & chewing action of
teeth
= in stomach curning action by the contraction
of muscles in the stomach wall
= increases the surface area of the food for
chemical digestion
37. ii- Chemical digestion :
= digestive enzymes break down complex food
molecules into smaller molecules which enter
the bloodstream to transported to whole body
= involves enzymatic hydrolysis
38.
39.
40. 2. Salivary gland
1. Epiglotis
3. Oesophagus
6. Gall blader
7. Pancreas
4. Liver
8. Large intestine
5. Stomach
9. Small intestine
10. Rectum
41. The components & functions of the human digestive
system
• Teeth – cut, tear & grind food
• Tongue – helps swallow food
• Salivary glands – release enzymes to break down carbohydrates
• Epiglottis – prevents food from entering trachea
• Oesophagus – tube connecting mouth to stomach
• Stomach – i. mixes food with more enzymes to break down proteins
ii. Hydrochloric acid kills bacteria
• Small intestine – food substances absorbed into the bloodstream
• Large intestine – reabsorption of excess water into the bloodstream
• Liver – i. removes toxins from bloodstream
ii. regulates food substances
iii. converts excess amino acids to urea
iv. Produces bile
• Gall bladder – stores bile which neutralises stomach acid
• Pancreas – secretes enzyme to break down carbohydrate, proteins & fats
• Rectum – stores faeces
• Anus – removal of faeces
42. Digestion in the mouth
• Digestion start here
• Chewing action breaks the food into smaller pieces
– exposes > surface area for enzyme’s reaction
• Food in mouth will trigger salivary glands (3 pairs) –
secretes saliva – contains salivary amylase
• Tongue – ensure food mixed well with saliva
• Salivary amylase – hydrolyse starch into maltose
• Thoroughly chewed food rolled into a mass called
bolus – preparation for swallowing
• Then, bolus enter the throat pharynx (junction of
alimentary canal & passage of air flows into the
lungs) oesophagus
• Epiglottis – a cartilage flap – will closed temporarily
the airway to prevent food from entering the trachea
Parotid
gland
Sublingual
gland
Submaxillary
gland
43. • Mucus lubricates the movement of the bolus along oesophagus by peristalsis
(series of wave-like muscular contraction along the oesophageal wall)
• The peristalsis action of the eosophagus wall squeezes the bolus down
• Bolus enter the stomach when the cardiac sphincter relaxes
Salive
3 salivary glands
-Sublingual gland
-Parotid gland
-Submaxillary
gland
Food
Starch Mouth
Site of
digestion
Digestive
juices
Digestive
enzymes
Salivary
amylase
Enzymatic
action
Starch maltose
+ water
Salivary
amylase
pH
6.5-7.5
44. Digestion in the stomach
• Stomach – thick wall, sausage-shaped organ, muscular sac with a
highly folded inner wall.
• Epithelial lining contains gastric glands secretes gastric juice
• Foods stay here for a few hours. It is thoroughly curned & mixed with
gastric juice by the peristaltic contraction of the stomach wall
• Gastric juice contains :
i. Hydrochloric acid – a) creates the acidic condition (pH 1.5 - 2.0)
for the optimal reaction of enzyme
b) stops the activity of salivary amylase
c) Helps to kill bacteria in food
ii. Enzymes - a) Pepsin : proteins to polypeptides
b) Rennin : caseinogen to casein
• Then, contents of stomach become a semi-fluid called chyme
• Chyme enters the duodenum when the pyloric sphincter relax
49. • Small intestine = duodenum +
jejunum + ileum
• Duodenum – 1st
part ; receive chyme
(stomach) & secretion (gall bladder &
pancreas)
• The digestion of starch, protein &
lipid takes place here
i) Pancreatic amylase : starch maltose
ii)Trypsin : polypeptides peptides
iii) Lipase : lipids fatty acid & glycerol
Digestion in the small intestine
Starch + water maltose
Pancreatic amylase
Polypeptides + water peptides
Trypsin
Lipid droplet + water peptides
Lipase
50. Bile
- Alkaline greenish-yellow liquid
- Stored in gall bladder
- Contains no digestive enzyme
- Creates alkaline environment
- Reduce the acidity of chyme
- Emulsify lipids by changing
lipids into tiny droplets
Pancreatic juice
- Contains enzymes pancreatic
amylase, trypsin & lipase
- Optimum pH required is
between 7.1 & 8.2
LIVER PANCREAS
secretes
Duodenum
51. • Ileum
- The wall secretes intestinal juice
Intestinal juice
i) contains digestive enzymes for digestion of peptides & disaccharides
ii) Require an alkaline medium for optimum reaction
* End of digestion process:
-i- all carbohydrates digested into monosaccharides (glucose, fructose
galactose)
-ii- proteins digested into amino acids
-iii- lipids digested into fatty acid & glycerol
-iv- vitamins & mineral (small & soluble – no need to digest)
-v- Dietary fibre – not digested
52. Protein digestion
Peptides are digested by erepsin (a peptidase) into amino acids
Peptides + water amino acids
erepsin
Carbohydrates digestion
Maltose is digested by maltase into glucose
The digestion of sucrose & lactose
Lactose + water glucose + galactose
lactase
Sucrose + water glucose + fructose
sucrase
Maltose + water glucose
maltase
53.
54. 1) Mouth
Here in the buccal cavity (mouth) the food is masticated (chewed). The buccal and naval cavity
also warm up the air so that it does not interfere with enzyme production. The saliva, which
contains Carbohydrase enzymes, changes starch into maltose.
55. 2) Oesophagus
Next the food travels through the oesophagus or gullet which links the mouth and stomach together.
These contract and push food along the gut, this is called peristalsis.
56. 3) Liver
The liver breaks up (emulsifies) fats by storing bile (the bile actually comes from the gall bladder).
It is also alkaline which is good for the enzymes by giving them a good pH for them in the small
intestine.
57. 4) Stomach
The food then enters your stomach. In your stomach starch, fat and protein are digested by enzymes.
Hydrochloric acid is present to kill and neutralise bacteria which gives a low pH for the enzymes to
work.
Enzymes work perfectly at human body temperature at ice temperature, enzymes become deactivated
but above body temperature they become denatured.
58. Pancreas
The pancreas’s job is to produce three types of enzymes in pancreatic juices:
Protease enzymes to digest proteins.
Lipase enzymes to digest lipids e.g.. Fats.
Carbohydrase enzymes to digest carbohydrates.
59. The small intestine/ileum produces more enzymes to break up more proteins, fats and
carbohydrates. It also absorbs the nutrients through the gut wall and into the blood
stream through these ingenious cells, the villi which line the small intestine which are
specially designed to absorb food efficiently. This process is a form of diffusion. Diffusion
is the process of which a substance, commonly gas, transfers from a state of high
concentration to low concentration to create balance.
Small Intestine
61. Rectum
Cellulose is often contained in foods. This cannot be digested so it must be egested. It is
stored as fasces. Finally it comes of of the anus.
