V IO

Animal Nutrition

❖ Plants = Autotrophs (Produce own food)

❖ Animals = Heterotrophs (Cannot produce own food; need to

obtain nutrients from the food they consume)

❖ Different animals have different diets (usual food or fluids that an

animal eats or drinks)

❖ There are three classifications of animals with regards to their

diet

➢ Herbivours (Eat Plant material e.g. Cows)

➢ Carnivours (Eat Meat e.g. Lion)

➢ Omnivours (Eat Meat and plant material e.g. Humans)

❖ Animals need a certain amount of essential nutrients

(chemical substances needed by living organisms to live and

grow) to stay healthy, for energy, for growth and for

maintenance

❖ These are found in the food we eat. We should aim for a

balanced of all the required nutrients.

❖ A balanced diet is when a person obtains all the required

nutrients in the correct quantities

❖ There are three main organic compounds

➢ Carbohydrates (used for energy)

➢ Proteins (amino acids build tissues)

➢ Lipids (protect vital organs)

❖ Other organic compounds include nucleic acids and vitamins

❖ Inorganic compounds = water makes up 60% of our cells

❖ Minerals are essential to be healthy such as calcium, phosphorus, iron and iodine

Nutrition for different

lifestyles❖ Nutrition = sum total of the processes involved in taking in and

using food for maintaining health, growth and energy.

❖ It involves:

➢ Ingestion (taking in food)

➢ Digestion (breakdown of large molecules into smaller ones)

➢ Absorption (molecules move through the wall of the small intestine into

the blood vessels and lymphatic vessels)

➢ Assimilation (nutrients move into the cells and used for various

functions)

➢ Egestion (elimination of nutrients that have not been digested or

absorbed)

❖ Trophic Feeding levels:

➢ Level 1: Producers (Plants)

➢ Level 2: Primary Consumers (Herbiviours)

➢ Level 3: Secondary Consumers (Carniviours)

➢ Omniviours eat from level 2 and level 3

❖ Herbiviours eat a lot of plants (rich in energy in the form of carbohydrates) but struggle to gain enough energy and nutrients from these plants.

❖ The reason from this is because cellulose is very hard to break down.

❖ Herbiviours do, however, produce enzymes to break the cellulose down. They also rely on bacteria in the digestive system to help with this breakdown.

Human Dentition

❖ Incisors

❖ Flat with sharp edges in the front of the mouth

❖ Used to cut food into pieces

❖ 8 in total – 4 in the top of the mouth and 4 in the bottom of the mouth

❖ Canines

❖ Found on either side of the incisors

❖ Pointy

❖ Used to tear and grip food

❖ 4 in total – 2 in the top of the mouth and 2 in the bottom of the mouth

❖ Premolars

❖ Larger teeth

❖ Flat outer surface with bumps on inner surface called cusps

❖ Next to canines toward the back of the mouth

❖ Used to grind food

❖ 8 in total – 4 in the top of the mouth and 4 in the bottom of the mouth

❖ Molars

❖ Larger than premolars and have more cusps

❖ Next to premolars at the back of the mouth

❖ 12 in total – 6 in the top of the mouth and 6 in the bottom of the mouth (3 on each side of the lower and upper jaw)

❖ Last molars are known as wisdom teeth – they often come out skew or not at all and are often removed

Tooth Decay

❖ Caused by plaque (sticky mixture of bacteria and the substance they produce) building up on the teeth

❖ These bacteria produce acids that dissolve enamel (hard surface of teeth) to form holes in the teeth

❖ Acid passes through the holes to the inner part and causes decay

❖ Consuming food and drinks high in carbohydrates and sugary substances will increase the risk of tooth decay

❖ Prevent by

❖ Avoiding eating too many sugar containing items

❖ Clean teeth twice a day with a toothbrush and a toothpaste containing fluoride

❖ Visit a dentist every six months

❖ Table 5.2 pg 154 Arguments for and against adding fluoride to tap water

ECOLOGICAL PYRAMID

❖ Most grass is not rich in other nutrients and therefore Herbivours need to eat a lot more to gain the required nutrients

❖ Dentition refers to the type, number and arrangement of a set of teeth

❖ Herbivores have broad flat, spade-like sharp incisors along their bottom jaw for cutting the plant material against the horny pad

❖ The horny pad is a hard area on the upper jaw and contains no teeth

❖ They have square molars with flat surfaces to crush plant material into fine pulp

❖ They have many faeces

❖ Carniviours are predators (hunt for food)

❖ It is hard for them to find food and they use a lot of energy for hunting

❖ Meat has less energy in the forms of carbohydrates but is richer in other nutrients

❖ Meat is easier to digest and their digestive system is shorter than those of Herbivours

❖ Food digested and absorbed effectively – little is wasted and little faeces compared to Herbiviours

❖ They have a wide mouth opening and their teeth are well adapted for grasping, tearing and chewing tough meat

❖ Carnivours have short incisors for shredding meat

❖ Very sharp long canines for killing and tearing meat

❖ Their molars are sharper with uneven bumps for

chewing the meat

❖ They have four triangular carnassial teeth with

jagged edges to slice the meat like a blade

❖ Omniviours’ teeth and digestive system are adapted to

their diet of both plant and meat

❖ They have canines to tear at the meat and flat square

molars that crush plant material.

❖ Human compared to chimpanzee canines?

❖ Humans have shorter and less sharp canines because we

now cook our food which makes it softer

❖ TABLE 2.2.1 (PAGE 164)

Digestive System

Digestive system

Mouth – food is ingested here. Contains teeth for mechanical

digestion and tongue for mixing food.

Salivary glands – secrete saliva which moistens the food and

contains an enzyme for breaking down starch

Oesophagus – moves food t the stomach by peristalsis

Cardiac sphincter – band of muscle that regulates the entry of

food into the stomach

Liver – manufactures bile, deaminases amino acids, metabolises

glucose and breaks down alcohol, drugs and hormones

Stomach – mixes food into a liquid called chime. Some

chemical digestion take place.

Gall bladder – stores bile until it is relased into the small intestine

Pyloric sphincter – band of muscle that regulates the exit of food from the stomach

Pancreas – secrete pancreatic juice containing enzymes for

digestion and secrete insulin and glucagon

Small intestine – final digestion of food. Most of the food is

absorbed

Colon – absorbs water and forms faeces

Appendix – no function for humans

Rectum – faeces are stored here

Anus – faeces released form body during process called egestion or defecation

Process Involved in Human

Nutrition1. Ingestion

❖ Taking in food via the mouth with the help of the lips, tongue and teeth

❖ The mouth is the opening to the digestive system

2. Digestion

❖ Process of breaking down food from larger molecules into simpler molecules

❖ Two types – Mechanical and Chemical

❖ Mechanical – Food broken down into smaller chunks by chewing (mastication), peristalsis through the oesophagus and churning in the stomach

❖ Chemical – Food broken down into smaller molecules through enzymatic action

❖ Digestion needs to occur so that nutrients from the food can be absorbed later on

Mechanical Digestion

❖ Starts in the mouth when we chew, bite and grind the food into smaller pieces, continues in oesophagus and ends in the stomach

❖ Aids chemical digestion by increasing the surface area of the food to be broken down by enzymes

❖ Mastication – chewing

❖ While chewing the tongue and teeth work the food into a moist ball called a bolus

❖ Bolus moves down the oesophagus via peristalsis

❖ Saliva containing amylase is created by the salivary glands

❖ Peristalsis

❖ The antagonistic contraction of the longitudinal and circular muscles in the gut wall

❖ Takes place in the oesophagus to push food down into the stomach

❖ Also occurs in the rest of the digestive tract to move food along

❖ Stomach

❖ The bolus enters the stomach from the oesophagus through the cardiac sphincter

❖ The stomach contains protease, hydrochloric acid (HCL), water and mucus

❖ The HCL maintains a pH of 2 in the stomach and neutralises the amylase coming from the mouth

❖ The water acts as a medium for the HCL, protease and food

❖ The mucus protects the lining of the stomach from being eaten away by the HCL

❖ The protease is involved in chemical digestion

❖ The food/bolus is churned into a liquid called chyme through peristaltic movements - this is part of mechanical digestion

❖ Enzymatic breakdown of food

❖ Enzymes are sensitive to pH and temperature.

❖ Starts in the mouth with amylase in the saliva – which breaks down starch to maltose (glucose unit)

❖ Continues in the stomach with protease – which breaks down proteins to polypeptides

❖ Ends in the Small Intestine – which contains amylase, protease and lipase

❖ These enzymes are secreted by the pancreas and transported into the small intestine through the common bile duct

Chemical digestion

❖ Amylase in the small intestine – breaks down maltose to

glucose/monosaccharides

❖ Protease in the small intestine – breaks down

polypeptides to amino acids

❖ Lipase in the small intestine – breaks down lipids to fatty

acids and glycerol

❖ Bile is secreted by the liver and stored in the gall bladder

❖ The bile helps with the breakdown of lipids and is

transported into the small intestine via the common bile

duct

❖ The pancreas is both an endocrine (secretes directly

into the blood) and an exocrine (secretes into ducts)

organ

The common bile duct is a small, tube-like

structure formed where the common

hepatic duct and the cystic duct join. Its

physiological role is to carry bile from the

gallbladder and empty it into the upper part of

the small intestine (the duodenum). The

common bile duct is part of the biliary system.

... Back to Liver.

Enzyme Where it is

produced

Substrate pH Digestive

juice

End

product

Carbohydrases Mouth

Pancreas

Carbohydrate

s

6-7 mouth

8 - intestine

Saliva,

pancreati

c juice

Maltose

/

Glucose

Proteases Stomach

Pancreas

Proteins 3 – stomach

8 - intestine

Gastric

juice,

pancreati

c juice

Polypep

tides/

Amino

acids

Lipase Pancreas,

small

intestines

Lipids 8 - intestine Pancreati

c juice,

intestinal

juice

Glycero

l and

fatty

acid

3. Absorption

❖ Occurs mostly in the small intestine (VILLI)

❖ Products of digestion move through the wall of the

small intestine into the blood vessels and the

lymphatic system

❖ More specifically the glucose/monosaccharides

and amino acids are absorbed into the capillaries

and the fatty acids and glycerol are absorbed into

the lacteal (part of the lymphatic system)

❖ Crypts of Lieberkuhn between villi secrete mucus

and produce new cells to replace those at the top

of the villi

❖ Four Adaptations of the Small Intestine

❖ Large surface area – 7m long folded into

finger-like structures called villi

❖ Thin surface – single layer of columnar

epithelium

❖ Surface should be in close contact – villi

have muscle strands that enable them

to move close to items to be absorbed

❖ Surface contains transport system –

capillaries and lacteal

Role of the VILLI

The villi absorbs digested nutrients by diffusion. These include amino acids, glucose, mineral salts, vitamins and water. These

nutrients are transported across the brush border into the

epithelial cells that line the villi. From there they move to the

other side of the epithelial cell and are then transported across

the membrane and into the blood capillaries within the villi

A villus is thin walled which allows for rapid diffusion of

dissolved nutrients and well supported with blood vessels for

transport of absorbed nutrients. It has a large surface area for maximum absorption, the walls are moist, is in constant motion

and they numerous in numbers

Diffusion and active transfer of nutrients into blood and lymhatic

system. Nutrients diffuse into the blood of arterioles of the villi.

From there they move into venules and eventually the hepatic

portal vein transports the nutrients to the liver. Energy is required

for active absorption from low to high concentration.

This energy provided by ATP.

Fats absorbtion is complex. Glycerol is soluble and is absorbed

ACTIVELY. Fatty acids combine with bile salts to form a soluble

fatty acid bile salt complex. It diffuses through the columnar

epithelial cells of the villi. Fatty acids separate from bile salts

again and recombine with glycerol to forms small fat droplets.

The triglycerides then combine with proteins to form small

particles called chylomicrons. The chylomicrons are absorbed

into capillaries called lacteals. The lacteals unite to form lymph

vessels and eventually the thoracic duct.

THE EFFICIENCY OF ABSORPTION

Length of ileum ensures max absorption of digested nutrients

Surface area for abortion is increased by folds of mucosa and

millions of villi with microvilli present

Chyme passes slowly through the small intestine

Movement of intestine wall and villi ensures close contact of

digest food with absorption area

Absorption surface is thin walled and consist of a single layer of

columnar epithelium cells

The absorption surface is moist caused by digestive juices and mucin

Well supplied with blood capillaries and lacteals in villi and

absorbed nutrients are quickly transported away

FATE OF ABSORBED NUTRIENTS

Fats – excess is converted by liver into glycogen

Amino acids – cannot be stored and are passed round the body for protein synthesis

Excess is deaminated by liver and converted into carbohydrates

Monosaccharides – excess is converted into insoluble glycogen and stored in the liver and muscles

Glucose is converted into glycogen and stored in muscle tissue

Much glucose is transported to body bells for cellular respiration

Some is converted into fats and stored in adipose tissue

Water – excess is excreted by kidneys as part of urine

Much is excreted by lungs as water vapour during exhalation

Used as solvent of body secretion

Used for maintaining body fluids such as blood and tissue fluid

The relationship with blood

and lymphatic systems

The hepatic artery, a branch of the aorta, supplies

the liver with nutrients and O2. The capillaries of the villi transport end products of digested food

and carbon dioxide via the hepatic portal vein to

the liver.

After exchange of substances between the cells

of the liver and the blood the remainder passes

via three hepatic veins into the inferior vena cava

The lacteals of the villi carry the absorbed fatty droplets to lymph vessels. The vessels unite to join

the thoracic duct which opens into the left

subclavian vein at the shoulder.

Outer wall

Inner wall

Pathway

for Food

Juices of digestion Saliva – in the mouth is the secretion of the salivary gland. It

consist of water, mucus, bicarbonate. It has a pH of 7,2.

Gastric juices – in the stomach is the secretion of the gastric

glands. It consist of water, mucin, enzymes, hydrochloric acid,

intrinsic factor, hormone and dissolved mineral slats.

Functions

Mucus – lines the inside of the stomach wall and protects it from

injury by the enzymes of the gastric juices

HCℓ – provides necessary acidic medium for enzyme action. It also

stops the action of swallowed saliva and acts as a germicide by

killing bacteria taken in with food. It is capable of converting some

sucrose into glucose and fructose

Intrinsic factors – assist in the absorption of Vit B12 thus preventing

anaemia

HYDROLYSIS

Pancreatic juice – is the secretion of the pancreatic cell. It

consists of enzymes and sodium bicarbonate. Pancretic juice

has a pH of 8

The enzymes assist in the digestion of starch, proteins and fats

into smaller molecules

Sodium bicarbonate neutralises the acid in chyme to create a

neutral or slightly alkaline medium for the action of enzymes in

the small intestine.

Succus entericus. – intestinal juice – secreted by the Crypts of

Lieberkhuhn found throughout the small intestine. It is an

alkaline secretion with a pH of 8. Consists of the several

enzymes needed to complete digestion

Catalyses carbohydrates, protein and fats into smaller molecules

which are the end products of digestion

Bile – by the liver and stored in the gall bladder. Contains no

enzymes and its pH is 8,3

Bile consists of bile pigments, bile salts, mineral salts, water,

mucus and cholesterol. Pigments are waste products and do

not participate in digestion.

Bile salts emulsify fats by breaking it up into small droplets

Mineral salts are alkaline and neutralise the acidity of chyme

Bile salts assist in the absorption of fats from the small intestine

Salts reduce the fluidity of chyme and promote peristalsis in the

small intestine

The bile is slightly antiseptic

It assist in the absorption of the fat soluble vit A D E and K

Sometimes the bile duct is blocked by gallstones, formed from a

hardened precipitate of cholesterol. If this happens the

contraction of the gall bladder will cause pain that can be felt

below the right scapula

4. Assimilation

Nutrients move in the blood to the liver to be processed then to the heart to be oxygenated and then to the cells to be used for various life processes such as building proteins from amino acids and breaking down glucose for energy during cellular respiration

❖ The capillaries in the small intestine join to form venules

❖ These venules join venules from the stomach to form the hepatic portal vein

❖ The hepatic portal vein carries the blood containing the nutrients to the liver

❖ The liver processes this blood by performing four functions on this blood

❖ 1. Deamination – excess amino acids are broken down, the nitrogen component is removed and converted into ammonia (which is very toxic) converted into urea which is excreted through the kidneys in urine

❖ 2. Detoxification – Alcohol/drugs and harmful substances are converted in harmless substances (If too many harmful substances enter the liver it may become over worked and shut down completely)

❖ 3. Breakdown of some hormones after they have performed their function such as insulin, oestrogen and testosterone

❖ 4. Conversion of glucose to glycogen for storage in the liver . Process is reversible, it is brought about by 2 hormones secreted by the pancreas (insulin and glucagon)

Bile contains no enzymes but has water which also

plays a role in chemical digestion

Water is required in chemical digestion because:

1. Acts as a solvent for the nutrients in the alimentary

canal

2. Provides a medium for enzymatic reactions to take

place

3. Acts as a lubricant and facilitates chewing and

swallowing

4. It is the reagent for hydrolysis

5. Egestion

❖ Removal of undigested food through the anus in the form of

faeces

❖ The undigested/unabsorbed chyme moves from the small intestine into the large intestine where most of the water is

absorbed

❖ Faeces is formed in the large intestine

❖ Faeces is stored in the rectum until it is eliminated from the anus

Homeostatic Control of

Blood Sugar Levels❖ Diagram pg 176

❖ After a meal the level of glucose in our blood increases to above normal levels

❖ The pancreas receptor cells sense this increase

❖ The pancreas responds by secreting the hormone insulin

❖ Insulin acts on the liver which then removes the glucose from the blood and converts it to glycogen

❖ Glycogen is stored in the liver

❖ Between meals the level of glucose in the blood decrease

❖ The pancreas receptor cells sense this decrease

❖ The pancreas responds by secreting the hormone glucagon

❖ Glucagon acts on the liver which then turns the glycogen back into glucose

❖ This glucose then enters the blood

Diabetes Mellitus

❖ Condition that occurs in people who do not secrete

insulin, secrete too little or have cells that are resistant to

insulin

❖ The excess glucose is not converted to glycogen and

hence the concentration of glucose in the blood rises

too high

❖ If the blood glucose level stays too high for too long a

period it can cause kidney damage, blindness or death

❖ Diabetes that develops later in life is largely due to bad

eating habits , being overweight and lack of exercise

NUTRITION FOR ENERGY,

GROWTH AND HEALTH❖ Many health problems can be prevented or

alleviated if we eat a healthy diet with the correct balance of nutrients

❖ Food contains energy which is used for various daily activities and life processes

❖ If we obtain more energy than we use it leads to weight gain

❖ To prevent weight gain we need to regulate what we eat and be aware of the energy values of our food items

❖ Energy is measured in units called joules (J) or Kilojoules (KJ) 1000J = 1KJ

❖ The amount of energy we need depends on our activity level, the more active we are the more energy we need

❖ Another factor that influences our energy needs is our Basal

Metabolic Rate (BMR)

❖ BMR – Energy needed when at rest to keep our life processes

going

❖ Factors that affect BMR

❖ Age – children use more energy as they are still growing. As we

get older our BMR decreases

❖ Gender – Males have a higher muscle mass and hence a higher

BMR

❖ At different stages in our lives our nutritional requirements

change

❖ Infants

❖ Beginning breast milk (perfect balance of nutrients a baby needs

and contains antibodies)

❖ 4 Months – semi-solid/liquid food as no teeth

❖ Toddlers – should be encouraged to eat fruit and vegetables

❖ Teenagers

❖ Undergoing growth spurts – need to eat energy rich foods that

are high in other nutrients such as calcium, iron, magnesium,

vitamin A, B, C and D

❖ Pregnant Women

❖ Need additional nutrients for the growth of the baby

❖ Eat more proteins and food containing vitamin D, calcium and

iron (example – milk and green vegetables)

❖ Elderly

❖ Eat less and hence they should make sure that their diet contains

a variety of food in order to obtain all the necessary nutrients

❖ People also make diet choices according to their

culture/religion or lifestyle

❖ Vegan

❖ No animal products (no meat, eggs, milk, cheese etc)

❖ No products tested on animals or products from animal parts

(leather )

❖ Vegetarian

❖ Similar to vegan but not as limiting

❖ Most do not eat meat

❖ Some eat fish and animals products, such as eggs and diary

❖ Halaal

❖ Followed by Muslims who follow the Islamic faith

❖ Dietary rules are very specific

❖ There is a list of forbidden foods such as pork, pork by-products, meat that is not slaughtered properly and alcohol

❖ These rules are found in the Qur’an

❖ Kosher

❖ Followed by those belonging to the Jewish faith

❖ Milk and meat products should not be mixed

❖ They should not be prepared together or stored in the same fridge

❖ Need to wait 6 hours after eating meat to eat diary

❖ These laws are called the laws of kashrut and they are found in the Torah

Dietary Supplements

❖ Are taken to supplement a diet lacking specific nutrients eg.

Vitamins, minerals and herbs

❖ Can come as pills, capsules, powders or liquids

❖ They often play a preventative role in medicine

❖ Eg. Pregnant woman take extra folic acid to prevent birth

defects

❖ Elderly woman take extra calcium to prevent osteoporosis

❖ Body builders take extra protein to build muscles etc.

❖ Take the supplement safely by:

❖ Telling your doctor about any dietary supplements you use

❖ Do not take a bigger dose than the label recommends

❖ Stop taking if you have side effects

❖ Read trustworthy information about the supplement

Malnutrition

❖ Poor nutrition – over nutrition (too much) or under nutrition (too little)

❖ An unbalanced diet can cause malnutrition as the individual is not getting the required nutrients

❖ Dietician – Health care professional who focuses on healthy food and nutrients to promote good health

❖ Causes

❖ Poverty – can’t afford food or can only buy cheaper food

❖ Lack of Education – people don’t know what a balanced diet is

❖ Lifestyle Choice – people know what a balanced diet is but choose to ignore it

Effects of Malnutrition

❖ Kwashiorkor

❖ Lack of protein, vitamins and minerals

❖ Staple diet of carbohydrates and living conditions are poor

❖ Swollen stomach, rest of body thin, diarrhoea, changes in hair

texture + colour, rash, swollen hands and feet

❖ Marasmus

❖ Lack of energy and proteins

❖ Result of general starvation, very thin

❖ Occurs mostly in babies and young children

❖ Anorexia

❖ Lack of desire to eat

❖ Eating disorder – starve themselves and become very thin

❖ Very dangerous as they loose the ability to see themselves

as they are

❖ Damage to the kidneys, reproductive systems and other organs. Damage may become permanent

❖ Symptoms – dieting but thin, lying about eating, obsession

with food

❖ Bulimia

❖ Eat a lot in a short period then get rid of the food by vomiting or using laxatives

❖ Liquid in the stomach is very acidic and this damages the

oesophagus and the teeth

❖ Symptoms – Over exercising, going to the bathroom right

after a meal, starving then binge eating

❖ Obesity

❖ Body stores extra energy as fat, this leads to weight gain

❖ Very fat is known as obesity

❖ Caused by too many sweet, starchy and fatty foods

❖ Can lead to diabetes as well as coronary heart disease

❖ Coronary heart disease – plaque (fat deposits) build up inside the arteries that supply blood containing nutrients

and oxygen to the heart muscle . Arteries become narrow

– blood flow slows or stops. This can lead to a heart attack

❖ Food Allergies

❖ Person’s immune system has a bad reaction to food items

– said to be allergic to an item - sees the item as harmful

to the body

❖ Common trigger is proteins such as fish, shellfish, eggs, nuts

or milk

❖ Person should stop eating the item if allergic – could lead

to malnutrition

❖ Food allergies should be managed with the help of a

doctor

Alcohol and Drug Abuse

❖ Alcohol abuse – becoming intoxicated/drunk

❖ Alcohol abuse can lead to alcoholism which is when one is dependant on alcohol (cannot function without it)

❖ If one is dependant on alcohol the only way to treat it is to stop drinking immediately and abstain from further drinking

❖ Drug abuse – when a person uses illegal drugs or when a substance alters their behaviour negatively

Effects of drug and alcohol

abuse in teenagers❖ Linked to teenage pregnancy and STDs as alcohol and

drugs lowers ones inhibitions

❖ They will do anything to get hold of substances such as stealing, sex for money/drugs/alcohol, sell drugs to make money

❖ It’s very bad for your health – it can damage your liver, teeth, oesophagus, stomach and even your brain

❖ An overdose can lead to death

❖ If a pregnant woman drinks alcohol regularly it can lead to Foetal Alcohol Syndrome – brains and bodies slow to develop – will always struggle in life

❖ It’s hard to stop once one is addicted – when one does stop they often experience withdrawal symptoms –shaking, sweating, bad headaches, depression