Chapter 6 nutrition
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Transcript of Chapter 6 nutrition
Chapter 6 :
Nutrition
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
Types of nutrition
Autotrophic
nutrition
Heterotropic nutrition
Photosynthesis
Chemosynthesis
Holozoic nutrition
Chemoautotrophs
Photoautotrophs
Saprophytism
Parasitism
Saprophytes
Parasite
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
Autotrophs
PhotosynthesisPhotos : light
- Green plants or photoautotroph- Produce organic molecules (food) from CO2 & H2O- Light as a source of energy
ChemosynthesisChemo : 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
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
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)
Carnivorous Plants : Venus Flytrap
Carnivorous Plants : Pitcher plant
ii. Saprophytism
• The organism are called as saprophytes, feed on dead & decaying organic matter
• Such as bacteria & fungi
• Digest food externally b4 absorb nutrient
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
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
The Importance of A Balanced DietBalanced 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 ofHealth
Type ofWork
Sex
Physicals activities
Environment
Body Size
Climate
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
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
• 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
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
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
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
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
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
Mineral element
Source Function Deficiency effect
Calcium Egg yolk, milk, cheese, cereal, green vegetable
- Strong bonesand teeth- Blood clothing
- Rickets- Osteoporosis- Tooth decay
Iron Egg yolk, meat, liver, spinach
- Component of the hemoglobin.
- Anemia- Tiredness
Phosphorus
Egg, milk, fish, green vegetable
- Strong teeth and bones
- Rickets- Muscles cramps- Tooth decay
Macrominerals Microminerals
- Required in large quantities- > than 100 mg per day- Eg : Magnesium, potassium, calcium, phosphorus, chlorine, sodium, sulphur
Phosphorus structural comp ofCalcium bones & teeth
Sodium nerve function & osmoticPotassium balance between body cellChlorine - 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
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
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 Faeces Made in
body Water gained total = 2600 cm³
Water lost total = 2600 cm³
Daily water balance
Functions:
Help in the transportationTo soften foodTo dissolve waste productsTo control the concentrationTo control body temperatureTo give shape to the body
Selection of appropriates balanced diet
Food guide pyramid
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
Kwashiorkor
Marasmus
• Vitamin deficiency :
- Vitamin C deficiency ; Scurvy ; swollen, bleeding gums & tooth loss
- Effects of overdoses of vitaminsVitamin 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
• Mineral deficiency :
- Shortage of ferum ; anemia
- Limited supply of Vit D, calcium & phosphorus ; rickets
- Lacking in calcium ; osteoporosis – bones
becomes porous & break easily
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.
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
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 glucoseB-proteins into amino acidC-lipids into glycerol & fatty acid
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
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
2. Salivary gland
1. Epiglotis
3. Oesophagus
6. Gall blader
7. Pancreas
4. Liver
8. Large intestine
5. Stomach
9. Small intestine
10. Rectum
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
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
Parotidgland
Sublingualgland
Submaxillarygland
• 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
Salive3 salivary glands-Sublingual gland-Parotid gland-Submaxillary gland
Food
Starch Mouth
Site ofdigestion
Digestivejuices
Digestiveenzymes
Salivary amylase
Enzymatic action
Starch maltose+ water
Salivaryamylase
pH
6.5-7.5
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
Secretion of gastric juice in the stomach
Food
Protein Stomach
Site ofdigestion
Digestivejuices
Digestiveenzymes
-Pepsin-Rennin
Enzymatic action
Proteins Polypeptides+ water
pepsin
pH
Around 2.0
Gastric juice contains hydrochloric acid & enzymes
Caseinogen casein+ water
rennin
• 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
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 PANCREASsecretes
Duodenum
• 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
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
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.
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.
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.
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.
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.
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
Large Intestine (Colon) The large intestine absorbs water and indigestible foods are stored here.
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.
Site of digestion
Gland/organ Digestive juice
Enzymes pH Food class
Mouth Salivary glands saliva Salivary amylase
6.3-6.8
Carbohydrates:
Starch maltose
Stomach Gastric gland Gastric juice Pepsin
Rennin
1.5
1.5
Proteins:
Protein polypeptides
Caseinogen casein
Duodenum Liver
Pancreas
Bile, bile salts
Pancreatic juice
None
Pancreatic amylase
Trypsin
Lipase
7.6-8.6
7.1-8.2
7.1-8.2
7.1-8.2
Emulsification of lipids
Carbohydrates:
Starch maltose
Proteins:
Polypeptides peptides
Lipids:
Lipid droplets fatty acids + glycerol
Ileum Intestinal gland Intestinal juice Maltase
Lactase
Sucrase
Erepsin
7.6
7.6
7.6
7.6
7.6
Disaccharides:
Maltose glu + glu
Lactose glu + galac
Sucrose glu + fruc
Proteins:
Peptides amino acids
Digestive system in ruminants
Digestive system in rodents