Obtaining Energy & Nutrients For Life Area of Study 2 Chapter 5 P94-135

Living Things – ‘energy trappers’ All living things trap _________ from their _________ __________. Plants, algae and some bacteria trap the ________ energy from the ______. These organisms are known as _________. Animals, fungi and most bacteria trap energy in the form of __________ energy present in their ______. These organisms are known as __________.

Trapping Radiant Energy The principal source of _______ _________ is that of sunlight. Plants and algae trap the sunlight and convert it to __________ energy in organic matter such as the carbohydrate _________. The ________ in which plants do this is known as ___________.

Trapping Radiant Energy ____________ is best described:

No Energy Trapping – No Life! If for some reason an organism cannot trap energy – What will happen to them? Living things can survive for some time using stored energy (______ in ________ – _______/_________ in plants). If however energy trapping does not resume – the stores will eventually _____ ________ and the organism will _______.

Why is Energy Needed? _________ is required so _______ things can carry out these four energy requiring processes: 1. Living things use energy to keep their _________ conditions within limits and at values that can differ from those in the _________ environment. 2. Living things use energy to ________ and __________ to changes in their external surroundings.

Why is Energy Needed? 3. Living organisms use energy to ________ new __________ similar or __________ to themselves. 4. Living organisms use energy to produce new organic matter needed for _______, __________ or _________.

Energy For Life Our bodies require a source of energy for various life sustaining functions. The energy expended by the body in sustaining life must be __________ by the energy obtained in the food eaten. Energy In > Energy Out = ___________ Energy In < Energy Out = ___________ Energy In = Energy Out = ___________

Ingestion of Food Different structures are used to _____ and ________ food. ________ use a hand to mouth process. Different _________ use a range of strategies to obtain their _______.

Mechanical Breakdown of Food Ingested food must be ________ before it can be _________ by the ______ of the body. In order to absorb as many _________ as possible – food must be ________ ______ into ________ pieces. The physical process of breaking ________ pieces of food into ________ pieces is called ‘_________ ___________’.

Mechanical Breakdown of Food

All __________ use their ________ and ________ to breakdown their food. There are four different types of teeth in mammals: __________ – get the food into the mouth __________ – tear and pierce the food __________ – grind food so it can be swallowed

Mechanical Breakdown of Food

The foods mammals eat determine their jaw and teeth structure.

The Digestive System The digestive system or _________ ________ is approximately ____ metres long and extends from the _____ to the _______.

The Digestive System Muscular wave __________ called ‘____________’ allows the food to keep traveling along the canal.

The Digestive System

The Mouth The mouth receives food where it both mechanically and chemically breaks down. Our saliva contains an enzyme called ‘amylase’ – which actively breaks starch and sugar molecules into smaller chains. When a person decides to swallow – a rounded mass of food (bolus) is forced to the back of the throat where an automatic swallowing response begins.

The Oesophagus The oesophagus is a soft muscular tube that secretes mucus and transports food from the mouth to the stomach using perstalsis movement (in approx 5 secs). As the openings to the oesophagus and trachea are very close to eachother – a small flap of skin ‘the epiglottis’ covers the trachea to let food go down the right tube.

The Stomach The oesophagus is connected to the stomach. When empty the stomach is roughly the size of a banana, but can expand significantly to accommodate the intake of food. When the stomach is stretched – nerve endings are stimulated to create the sensation of being ‘full’.

The Stomach Also when the stomach is stretched – gastric juices are secreted. Gastric Juices are a mixture of mucus, enzymes, hydrochloric acid an water. Gastric Juices are secreted by specialised cells located in the lining of the stomach wall.

The Stomach With the release of Gastric Juices, an inactive enzyme called pepsinogen is converted into the active enzyme Pepsin to also aid the breakdown of food. The secreted mucus helps protect the lining of the stomach and stops the onset of peptic ulcers. Food broken down chemically in the stomach forms a solution called ‘chyme’.

The Small Intestine Once food in the stomach has been mechanically and chemically broken down – it is forced out into the small intestine via the pyloric sphincter. The small intestine is approx 6.2m long and 2.5cm in diameter. The small intestine is broken into 3 parts – the duodenum, jejunum and ileum.

The Small Intestine Digestion in the small intestine relies on secretions from 3 organs that are connected to it. The Pancreas, Gall Bladder and Liver all secrete hormones and enzymes that aid the absorption of nutrients.

The Duodenum The duodenum is about 25cm long and is the first part of the small intestine. Secretions from the pancreas enter the duodenum via the pancreatic duct.

The Duodenum

The Pancreas Secretions from the pancreas include: Bicarbonate – neutralises stomach acid Amylases – break down carbohydrates Protein Digesting Enzymes Lipases – turns fats into fatty acid and glycerol Nucleases – breaks opens the cells in food

The Liver & Gall Bladder Cells of the liver produce bile. Bile exits the liver via the bile duct into the duodenum, where it then moves into the gall bladder where it is stored and concentrated. Bile is a greenish fluid which contains bile salts, cholesterol and bilirubin. Bile breaks up large fat droplets into smaller droplets in a process called emulsification.

The Liver & Gall Bladder Lipases from the Pancreas also aid in the breakdown of fat into fatty acids and glycerol. The fat droplets must be small enough so as the intestinal cells can absorb them. Fatty foods satisfy our appetites because it simply takes longer to break them down and absorb – so they are in our systems for longer.

The Jejunum & Ileum Food in the duodenum moves along the gut and into the jejunum (2.5m) and then into the ileum (3.6m). Cells from the jejunum and ileum secrete enzymes to complete the following tasks: (aminopetidases) ProteinsAmino Acids (aminopetidases) ProteinsAmino Acids (maltase) MaltaseGlucose (maltase) MaltaseGlucose

Absorption in the Small Intestine The small intestine is designed to absorb nutrients from digested food. The lining of the gut has small folds to increase surface area – more absorption. Surrounding each fold are small finger like projections called villi. Villi again help increase surface area.

Absorption in the Small Intestine

Amino acids, glucose, fructose, galactose, glycerol and fatty acids are all absorbed in the small intestine. Nutrients are absorbed through the cell lining into the bloodstream by diffusion. Diffusion is the movement of particles from an area of high concentration to an area of low concentration.

Absorption in the Small Intestine

The Large Intestine The large intestine is about 1.5 metres long and consists of two parts – the colon and rectum. The colon converts fibre into fatty acids and absorbs water and electrolytes such as sodium and chloride.

The Large Intestine The colon pushes the remaining undigested contents (faeces) into the rectum. Faeces contains undigested fat, protein, bacteria, dead cells, water, fibre and inorganic matter. The bile released earlier gives faeces the colour that it is.

The Digestive System - Review Bio-challenge Questions p124