Biology G10Chapter 13: Heterotrophic Nutrition

Heterotrophic Nutrition

Autotrophic organisms can make their own food

Heterotrophic organisms must take in food from enivron.

Heterotrophic nutrition is the breaking down of complex organic molecules into smaller, soluble molecules

These are absorbed to provide energy and nutrients for survival and growth

There are four types of heterotrophic nutrition Holozoic Saprobiontic Parasitic Mutualistic

Heterotrophic Nutrition

Holozoic involves digesting food inside the body

Humans, mammals Saprobiontic feeds on dead

organic matter, digestion takes place externally

Bacteria, fungi Parasitic obtains food from

another organism by living inside it

Mutualistic involves two way nutritional gain for two different org's

A Balanced Diet in Humans

A balanced diet provides enough of all nutrients to maintain good health

Carbohydrates and lipids for energy Proteins for growth and repair Vitamins, mineral ions and water Fibre for digestions

Not classified as nutrient because not digested and absorbed Amount of each nutrient varies by age, gender, activity

level and pregnancy Dietary reference value table used to estimate Only a guideline

Components of Human Diet

Energy is needed for the following: Growth and maintenance of body tissues Maintain body temperature Muscle action (walking, exercise) Involuntary muscle action (heartbeat)

Energy balace requires comparing food energy in with energy used by these activities

If more food energy is brought in than is used by activities an person will gain weight as stored energy

If less food energy is brought in than is used a person will loose weight by using stored energy

By adjusting diet and activity a balance can be attained

Components of Human Diet

Carbohydrates are the main source of energy Sugars and starchs (potato, rice)

Starch and disacharride sugars are broken down into monosacharrides (mostly glucose)

Glucose is used in respiration to general energy Cellulose is not digested but it is the main type of fibre

Fibre is important for maintaining health digestion and digestive tract

Components of Human Diet

Lipids are also a source of energy and other functions Excess lipids are stored under the skin and around organs Provides energy store and thermal/mechanical insulation

Lipids also used to make cell membranes Essential fatty acids must be obtained from diet and cannot

be synthesised in the body Excess amounts of saturated fatty acids can cause heart

disease and buildup in arteries Replacing unsaturated fatty acids reduces this risk

Components of Human Diet

Proteins are essential for growth and repair Broken down into amino acids which are then used to build

up new tissure and repair damaged tissues (4% per day) Enzymes and hormones must be replaced

Body requires 20 different amino acids 9 are essential amino acids (cannot be made in the body)

If essential amino acids are missing from the diet certain enzymes cannot be synthesised properly

First-class proteins have many amino acids Meat, eggs

Second-class proteins have few amino acids Wheat, rice

Components of Human Diet

Water is essential part of body fluids Blood, aqueous chemical reactions in cells

Components of Human Diet

Vitamins and mineral ions are required for Vision Respiration Connective tissue Teeth and bones Nerve function DNA Haemoglobin

The Digestive SystemThe sequence of processes as food passes through

the digestive systemMechanical digestion

Food broken down into small particles with large surface area

Chemical digestion Digestive enzymes break down food molecules to be absorbed

Absorption Digested materials are taken into the bodies cells

Assimilation Absorbed food materials are converted to new protoplasm

Must first understand the organs and tissues

The Alimentary CanalOne long continuous tube from the mouth to the

anus:

Mouth and PharynxMouth

Food first enters the bodyMechanically ground smaller by teethTongue rolls food into a bolus for easy swallowingSaliva lubricates and starts to digest food

PharynxConnects the mouth and oesophagus: “throat”Air and food both use this passageLarynx moves up during swallowing to prevent food

from entering the airway (trachea)

Mouth and Pharynx

OesophagusLong, narrow, muscular

tube that connects the pharynx to the stomach

Peristalsis moves bolus quickly to stomach

Ends at cardiac sphincter stopping backflow from stomach

No villi/microvilli

StomachMuscular, stretchable bag

with many musclesFood is mixed with enzymes

and gastric juicesFood becomes semi-liquid

“chyme”The pyloric sphincter stops

the food from entering the small intestine until ready (2 – 6 hours)

No villi/microvilli

Small IntestineMost of digestion occurs hereThree main parts:

In duodenum pancreas adds juicesJejunum coils for 2 metersIleum coils for 4 – 6 meters

Very long to allow enzymes to digest food

Food absorption occurs hereIleum connects to large intestine

Absorption / AdaptionsSmall intestine has special adaptations to increase

surface area for absorptionSingle layer epithelium layerInner walls shaped as transverse, circular foldsAlong folds are finger-like villi sticking outAlong villi are microscopic microvilli on each cell

Well supplied with capillaries and lymphatic capillaries (fat soluble products)

Adaption for Absorption

Large IntestineLarger in diameter but much

shorter (1.5 m)The main purpose is to absorb

water and mineral salts

No digestion occurs here

Faeces (undigested food) is stored in rectum before being expelled through anus

Bacteria living here produce vitamins (K)

LiverDark red, made of five

lobesMakes bile – alkaline

liquid with bile saltsHelps break down fatsStored until needed in

the gall bladderBile emptied into

duodenum

PancreasSecretes pancreatic

juice through bile duct into duodenum

Digestive enzymes and insulin addedResponsible for blood

sugar regulation

How is Food Digested - MouthMechanical digestions?Chemical digestion is breaking food down into

simple, soluble substancesSaliva in the mouth mixes with the food

Mucin softens the food for rollingAmylase starts to break starch into maltose

In the StomachMechanical digestion?Chemical digestion

Hydrochloric Acid (HCl) Stops amylase Kills bacteria, germs, parasites Provides optimum pH for enzymes Activates digestive enzymes so they don’t eat stomach cells

Pepsinogen -> pepsin Prorennin -> rennin

In the StomachPepsin digests proteins to polypeptides

Rennin clots/curdles milk proteins to keep them in the stomach to be digested

In the Small IntestinePancreatic and intestinal juices are alkaline

Nuetralizes acid from stomach

Intestinal Juice Pancreatic Juice

Maltase Pancreaic amylase

Lactase Trypsinogen

Sucrase Pancreatic lipase

Erepsin

Enterokinase

Intestinal lipase

Small Intestine - CarbohydratesStarch digested to maltose in mouthPancreatic amylase digests remaining starchLactase and sucrase digests other carbohydrates

Small Intestine - ProteinsUndigested protein is digested by trypsin into

polypeptidesErepsin breaks polypeptides into amino acids

Small Intestine - FatsFats must first be emulsified to be digested

Bile and bile salts break apart fats making an emulsionLipases digest fats to fatty acids and glycerol

The Absorption ProcessBy the end of digestion in the ileum:

All carbohydrates are monosaccharides (mostly glucose)All proteins are amino acidsAll lipids are fatty acids and glycerol

Glucose and amino acids absorbed through villi into cappilairesFatty acids and glycerol absorbed into lymph system

Saprobiontic Nutrition Obtain nurtrients and energy from dead organic matter

and organic waste (faeces)

Enzymes are secreated onto food to digest outside org. Extracellular digestion

Soluble products are absorbed into organism

Many bacteria and fungi are saprobionts

Rhizopus (pin mold) grows on stored foods Branches called hyphae grow out of food No divisions between cells: continuous cytoplasm Small round pin heads are sporangia (spore case) Enzymes are secreated onto the food substrate

Saprobiontic Nutrition

Parasitic Nutrition

Obtains nutrients from living organisms (host) Can live on or in another species

Tapeworm lives in pigs and transfers to humans Flat, ribbon-like body made up of segments Head (scolex) is embedded into intestine wall Eggs are developed and pass out in faeces Pigs are infected from faeces, eggs hatch inside pig Worms live in muscle tissue of pigs which is eaten by

humans Long thin shape allows food to pass without major

problems

Parasitic Nutrition

Adaptations of Tapeworm

Attachement structure to hold worm inside intestine Living in intestine provides constant supply of food Protective cuticle protects it from digestive enzymes Can survive in low oxygen environment Reduction of sense organs (lives in the dark) Hermaphroditic can reporoduce by itself Each segment produces eggs so that huge numbers of

eggs are released each cycle

Mutualistic Nutrition

Close relationship between organisms of different species where both gain a nutritional advantage

Bacteria live in human large intestine Microorganisms live in cow/sheep stomachs help digestion Lichens are combination of algae and fungi

Rhizobium (bacteria) live among the roots of legumes Attracted by hormone secreated by plant roots Nodules develop on the roots that contain the bacteria Bacteria convert nitrogen into ammonia Ammonia is then used by plant for protein synthesis Bacteria is supplied with sugars from the plant

Mutualistic Nutrition