2.4: Adapations for nutrition

Autotrophic

Create their own nutrition from simple organic raw materials.

Photoautotrophic

Create their own nutrition with the sunlight as an energy source, includes green plants, some protista and bacteria.

Holophytic

Word used to describe photoautotrophs.

Chemoautotrophic

Use energy from chemical reactions, includes all prokaryotes. Less effective than sunlight.

Chemosynthesis

Process in which glucose is created using chemicals as an energy source.

Heterotrophic

Consume other organisms for nutrition that either eat autotrophs or have eaten organisms that eat autotrophs.

Saprotrophic

Feed on dead or decaying matter. Have no digestive system, so secrete enzymes onto food for extracellular digestion, before absorbing the soluble products of digestion.

Saprobionts

Word for saprotrophic animals, including all fungi and some bacteria. Example is decomposers, which are necessary for recycling nutrients and decaying leaf litter.

Parasitic

Obtain nutrition from their host, which is a living organism that is harmed and even killed due to this process.

Endoparasitic

Parasites that live in the bodies of hosts, such as tapeworms.

Ectoparasitic

Live on the surface of the host, such as head lice.

Holozoic

Nutrition used by most animals, where food is ingested, digested and egested inside of the body.

Detritivores

Type of holozoic nutrition where organisms feed on dead or decaying matter.

Amoeba

Unicellular organism that feeds off holozoic nutrition. Takes in food through cell membrane, where they are converted to food vacuoles and fuse with lysosomes.

Hydra

A multicellular organism with a singular hole and six tentacles. It is dibloblastic. Digests mainly extracellularly and absorbs the nutrients. Has photosynthesising protista which pass sugars to it.

Diploblastic

Type of animals that has two layers of cells separated by a jelly layer.

Ectoderm and endoderm

Two cell layers in diploblastic animals - separated by a jelly layer.

Gut

Long, hollow, muscular tube that moves food contents in humans via peristalsis.

Peristalsis

Method used by the gut to move food along the body, via contractions of the gut muscles.

Mechanical

Type of digestion where food is crushed by teeth or by gut muscle contractions.

Chemical

Type of digestion where food is broken down by enzymes, bile and stomach acid.

Serosa

Outermost layer of gut wall, made of tough connective tissue. Protects gut wall and reduces friction against the gut and other abdominal muscles.

Submucosa

Second innermost part of the gut wall, made of connective tissue that contains nerves to coordinate peristalsis and lymph vessels to remove absorbed products of digestion.

Circular

Innermost muscles in the gut wall, contract behind the ball of food.

Longitudinal

Outermost muscles in the gut wall, relax in front of the ball of food.

Mucosa

Innermost layer, secretes mucus for digestion and protection, and sometimes secretes digestive juices and absorbs digested food.

Amylase

Enzyme that hydrolyses starch and glycogen to the disaccharide maltose.

Carbohydrase

Term for carbohydrate hydrolysing enzymes, such as amylase, maltase, sucrase and lactase.

Endopeptidase

Enzyme that hydrolyses bonds within the protein molecule.

Exopeptidase

Enzyme that hydrolyses terminal or penultimate bonds at the ends of shorter polypeptides.

Peptidases

General term for protein hydrolysing enzymes.

Lipase

Breaks down fats into monoglycerides and fatty acids.

Buccal cavity

Where teeth and saliva are used to digest food.

Saliva

In the buccal cavity, containing amylase, hydrogen carbonate, carbon trioxide, mucus. Optimum pH of 6.7-7.

Oesophagus

Carries food to the stomach.

Stomach

Where most chemical digestion occurs, with a volume of 2 dm3 and gastric juice.

Sphincters

Rings of muscles that contract to keep food in the stomach.

Oblique

Extra layer of muscles in the stomach, between the circular and longitudinal muscles.

Gastric juice

Secreted by glands in gastric pits.

Rugae

Large folds in the mucosa.

Gastric pits

Depressions in the mucosa with glands that release gastric juice.

Zymogen/chief cells

Secrete pepsinogen at base of gastric pit, which is activated by H+ ions to pepsin, an endopeptidase.

Pepsinogen

An inactive enzyme which is released by chief cells. Activated by H+ ions to pepsin, an endopeptidase.

Pepsin

An endopeptidase activated by H+ ions from pepsinogen, used in ruminant stomachs.

Hydrochloric acid

Lowers stomach pH to around 2, which is optimum for enzymes and kills most bacteria in food. Secreted by oxyntic cells near the base of the gastric pits.

Oxyntic cells

Secrete hydrochloric acid in the stomach, near base of gastric pit.

Mucus

Secreted by goblet cells at the top of the gastric pit, lubricates food and protects stomach wall.

Small intestine

Has two regions, and is where absorption and some chemical digestion occur.

Duodenum

Receives secretions from liver and pancreas. First part of small intestine, takes up 25cm.

Ileum

Where absorption occurs. Has folds, villi and microvilli. Several metres long.

Bile

Secreted by liver, stored in gall bladder and passes through the bile duct. Has no enzymes, has bile salts which are amphipathic, is alkaline and emulsifies lipids.

Gall bladder

Where bile is stored.

Bile duct

Where bile passes through to reach the small intestine.

Pancreatic juice

Secreted by islet cells in the pancreas and contains trypsinogen, amylase, lipase and sodium hydrogen carbonate to raise pH to slightly alkaline.

Islet cells

Secrete pancreatic juice. Exocrine glands.

Exocrine glands

Secrete substances onto epithelial tissue.

Trypsinogen

Inactive enzyme in pancreatic juice, converted to the endopeptidase trypsin by the duodenal enzyme enterokinase.

Enterokinase

Duodenal enzyme that converts trypsinogen into the endopeptidase trypsin.

Crypts of Lieberkuhn

Where Brunner’s glands are located.

Brunner’s glands

At base of crypts of Lieberkuhn, secrete alkaline secretions.

Lacteals

Lymph capillaries in the villi.

Lymph

A colourless liquid containing white blood cells.

Lymphatic system

Transports fat-soluble molecules into the subclavian vein.

A, D and E

Vitamins that are fat soluble, and are absorbed in lacteals.

Large intestine

About 1.5metres long. Made up of the caecum, appendix, colon and the rectum.

Caecum

Where undigested food, mucus, bacteria and dead cells enter the large intestine.

Colon

Food enters here from the caecum. Has less villi then the ileum, and absorbs water and minerals. Mutualistic enzymes secrete folic acid and vitamin K.

Rectum

Food enters here from the colon, in a semi-solid state. It is egested here as faeces, a process known as defecation.

Pork tapeworm

A gut endoparasite, has two hosts, the human and the pig. Larval forms develop in a pig’s muscles and remain dormant until consumed by a human host, which then contaminates pig’s food.

Scolex

Anterior end of a pork tapeworm, made of muscles with suckers and a double row of curved hooks.

Proglottids

Linear sections that make up a pork tapeworm. Have male and female reproductive parts, which can have up to 40,000 eggs each.

Anti-enzymes

Made by pork tapeworms to inhibit enzymes.

Cuticle

Pork tapeworms thick body coating to protect from host’s immune system and enzymes.

Pediculus

A ectoparasite, with each species specialised to a different host and even different body sections. Wingless, poorly adaptated to movement and travel via direct contact.

Nit

Shells left behind after a louse hatches, after 1-2 weeks of incubation.

Nymph

Hatched form of a louse. Takes 10 days to mature to adult. Feeds from host’s blood.

6\.2-7.4

What mouth pH varies between.

6\.7-7.0

Salivary amylase optimum pH.

Taeniasis

Condition caused by a long-term pork tapeworm infection, causes abdominal pain and weakness.

Amphipathic

Molecules that have hydrophilic and hydrophobic parts.

Trypsin

An endopeptidase converted from trypsinogen by the duodenal enzyme enterokinase.

Palate

In mammals, to separate buccal and nasal cavities, allowing them to breathe and eat at the same time.

Incisors

Located at the front of the mouth, only on lower jaw of herbivores. For slicing grass or tearing muscle from bone.

Smooth lining

On a carnivores large intestines, which are also straight.

Canines

Large, curved and pointed in carnivores but indistinguishable from incisors in herbivores. Slice through grass or tear muscle from bone and kill prey.

Premolars and molars

At the back of mouths, for grinding and chewing. In plants, are flat and interlock, with unrestricted roots to allow for constant replacement of worn down material.

Grinding ridges

On herbivore molars and premolars. Worn down over time to expose sharp edged enamel ridges, improving grinding efficiency.

Cusps

On carnivore premolars and molars, sharp points for cutting and crushing.

Carnassials

Specialised cheek teeth in carnivores. Two on each side, which slide off each other. Sharp, large and located towards the back of the mouth. They shear muscle off bone.

Vertical

Movement of carnivore jaws, allows for the mouth to open wide but requires strong muscles. Carnivore skulls have protrusions on the skull to allow these muscles to insert into bone.

Pouched

How herbivore and omnivore small intestines are described, like this as plant material produces more faeces, such as cellulose.

Dental pad

Above incisors and canines in herbivores, where grass is sliced against.

Horizontal

Movement of herbivore jaws. They do not need strong jaws and therefore they have a smooth skull with no muscle protrusions.

Ruminants

Group of herbivores that have a rumen for cellulose digestion.

150dm3

Size of rumen.

Cud

Formed by ruminants from chewing and mixing with saliva, and reformed by reticulum.

Rumen

First part of ruminant stomach which contains microbes such as fungi, bacteria and protista which secrete enzymes to digest cellulose to glucose.

Organic acids

The cud is fermented into this in the rumen, which is a source of energy in the cow. Also released is methane and carbon dioxide.

Reticulum

Part of ruminant stomach that reforms fermented grass into cud, and passes it back up to the mouth to be chewed again. This can happen multiple times.

Omasum

Part of ruminant stomach where water and organic acids are absorbed.