Common Requirements of living things - ANIMALS – Chapter 5

Autotrophic Unicellular Organisms

Water + dissolved Inorganic nutrients

Carbon dioxide+ Oxygen

Light energy Heat energy

Organic compounds

Carbon dioxide+ Oxygen

WastesDiffusion & osmosis in / out of the cell - Active & Passive

Heterotrophic Unicellular Organisms

Water + dissolved Inorganic nutrients

Oxygen

Organic matter‘food’ Heat energy

Water + dissolved Inorganic nutrients

Carbon dioxide

Organic wastes

Diffusion & Osmosis in and out of the cell - Active and passive Phagocytosis or endocytosis of organic matter

No Digestion Required

• Very few multicellular animals absorb nutrients directly from the

environment.– Exceptions include parasites that

absorb nutrients that have been digested by the host.

– In such cases there is no need for digestion

– Examples :• Blood parasites• Protozoan parasites• Tapeworms• Acanthocephalans

Most reef-building corals have a symbiotic relationship with photosynthetic algae, called zooxanthellae. which live in their gastrodermis tissue.

The zooxanthellae convert sunlight, carbon dioxide, and water into oxygen and carbohydrates that feed the coral polyps and help them produce reef-building calcium carbonate.

In return, the corals provide the zooxanthellae with protection and the compounds they need for photosynthesis. Pigments in zooxanthellae also give corals their beautiful orange, red, purple, and yellow colors.

Corals

Movement of substances into & out of unicellular organisms

Passive diffusion in and out

Bulk Transport requiring energy

Intracellular Digestion• In intracellular digestion, food particles are engulfed by

endocytosis and digested within food vacuoles.– Protozoa, sponges.

Cell Specialisation in Simple Multicellular Organisms

Sponge feeding

Cell Specialisation in Simple Multicellular Organisms

Sponge feeding

Extracellular Digestion

• Extracellular digestion is the breakdown of food particles outside cells.– Digestion occurs in the alimentary canal.– Cells lining the lumen of the alimentary canal are

specialized for secreting enzymes or absorbing nutrients.

Intracellular v Extracellular Digestion

Cell Specialisation in Simple Multicellular Organisms

Cell Specialisation in Simple Multicellular Organisms

Cnidarians feeding

Feeding Mechanisms – Particulate Matter• The upper portion of lakes and oceans

contains very small animals and plants (plankton) that drift with the water currents.

• Along with plankton, there is also organic debris floating in the water column and mixed in with the sediment.

• Many organisms feed on this particulate matter.

Feeding Mechanisms – Particulate Matter

• Suspension feeders use ciliated surfaces to create a current that draws drifting food particles into their mouths.– Many use mucous sheets to

entrap food.• Tube dwelling polychaetes, • bivalve molluscs,

hemichordates, protochordates.

Feeding Mechanisms – Particulate Matter

– Others use sweeping movements of setae-fringed legs to create currents.• Fairy shrimp,

daphnia, barnacles.

Feeding Mechanisms – Particulate Matter

• Filter feeding is a form of suspension feeding that involves straining food from the water as it passes through a filtering device.– Herring, menhaden,

basking sharks, flamingos, baleen whales.

Feeding Mechanisms – Particulate Matter

• Deposit feeders consume the organic matter (detritus) that accumulates on the substratum.– Many annelids simply eat the

substrate, digesting organic matter.

– Others use appendages to gather organic deposits and move them to the mouth.• Scaphopods, sedentary or

tube-dwelling polychaetes, some bivalves, some annelids.

Feeding Mechanisms

• Predators have evolved a variety of ways to capture, hold, and swallow prey.– Many swallow food items whole.– Some have specialized teeth,

beaks, or tooth-like structures.– Some have highly elastic jaws and

distensible stomachs to accommodate large meals.

Cell Specialisation in Vertebrate Multicellular Organisms

Cell Specialisation in Vertebrate Multicellular Organisms

The different systems!Animal’s bodies are

composed of different systems, each system has

it’s own functions. All together these systems

work together to enable the animal to survive.

http://video.nationalgeographic.com/video/player/science/health-human-body-sci/human-body/human-body-sci.html

Obtaining nutrients and energy• Animals are heterotrophs must consume food in order to

obtain nutrients and energy.• Animals are adapted to obtain food in a variety of ways

python vs croc

Why We Eat

• Regardless of what an animal eats, an adequate diet must satisfy three nutritional needs:– Fuel/ Energy for all cellular work.– Nutrients:• The organic raw materials for biosynthesis.• Essential nutrients, substances such as vitamins that

the animal cannot make for itself.

Required Nutrients

• Carbohydrates - source of immediate energy for all living organisms. The monosaccharide glucose is broken down to make ATP in cellular respiration.

• Lipids- Fats and oils required for cell membranes, hormones and vitamins.

• Amino Acids - The building blocks of proteins. The body can make some amino acids but others it can’t make these are the 9 essential amino acids. Need to be regularly eaten.

• Vitamins - Organic compounds needed for cellular processes, e.g. making enzymes.

• Minerals - needed for structural components and for enzyme molecules.

The Digestive System• Ingestion- intake of food into the body• Digestion- physical and chemical breaking down of food• Absorption- nutrient molecules move into the circulatory

system and ultimately into the cells.• Egestion/ Elimination- removal of waste from the body

Two Types of Digestion.Physical digestion.– Food physically broken it down into smaller pieces in order

to increase surface area and enable maximum efficiency of chemical digestion.

Teeth

Mammalian teeth are specialized for different functions.

Incisors – biting, cutting, stripping leaves.Canines – seizing, piercing, tearing.Premolars & molars – grinding and crushing.

Teeth

Mammalian teeth are specialized for different functions.

Incisors – biting, cutting, stripping leaves.Canines – seizing, piercing, tearing.Premolars & molars – grinding and crushing.

Feeding Mechanisms• Herbivorous animals have

evolved special devices for crushing and cutting plant material.– Snails have a radula for scraping

algae or plant material.– Insects have grinding & cutting

mandibles.

Feeding Mechanisms• Herbivorous animals have evolved special devices

for crushing and cutting plant material.– Mammals have wide corrugated molars for grinding.

Feeding Mechanisms• Fluid feeders may bite and rasp at host tissues, suck

blood, and feed on contents of a host’s intestines.– Many have specialized tubelike mouthparts.

Chemical DigestionBreakdown of macromolecules by enzymes- made in the gut, salivary glands and pancreas into molecules small enough to be absorbed through the alimentary lining.

Amylases- Break down starches into simple sugars

Proteases- Break down protein-into amino acids

Lipases- Break down lipids into glycerol & Fatty acids

Introduction to the Human Alimentary System animation

Human digestion overview

View animation then have a go at the quizzes and labelling

exercises

Digestion• Stomach - majority of digestion occurs

– Mechanical digestion occurs as the muscles crush and move the food.– Chemical digestion also occurs in the stomach, with the secretion of

gastric juices with have enzymes that break down the food.• Small intestine -further digestion occurs but only on proteins and

carbohydrates to break them down into their amino acid building blocks.

Digestion-video.htm

AbsorptionMost occurs in the small intestine. Food at it’s smallest is then absorbed by the cells of the intestine and passed along to the blood stream.

Other mammals• Different diets require different digestive systems. • Breaking down cellulose requires the enzyme cellulase. • Mammals can’t make this enzyme.• Cows have a 4 chambered stomach. • They chew and then regurgitate their food and chew it again before sending it

to the rumen where heaps of cellulose digesting bacteria live and allow the breakdown of the cellulose to occurs.

Carnivore v Herbivore

Caecum: a pouch extension at the junction of the small & large colon which in herbivores contains cellulose digesting bacteria.

Herbivorus mammals with higher fibre diets may have larger caecums to maximise the opportunity for cellulose digestion by bacteria.

Digestion in birdsMost (not all) birds have :• a crop for temporary storage • a glandular part the proventriculus which

secretes mucus , HCl & enzymes• a muscular gizzard which may contain grit or

small stones which grinds and mixes the food and enzymes etc.