Chapter 11 - Adaptations for Nutrition Flashcards
What is an autotrophic organism?
Organisms that make their own food from the simple inorganic raw materials, carbon dioxide and water (Photo and chemoautotrophs).
What is a heterotrophic organism?
Organisms that can’t make their own food and consume complex organic molecules produced by autotrophs.
What are the 3 types of heterotrophic organism?
- Saprotrophic, enzymes secreted for extracellular digestion.
- Parasitic, obtain their nutrients from another living organism.
- Holozoic, ingest food, digest it and egest the indigestible remains.
Why must food be digested?
The molecules are…
- Insoluble and too big to cross membranes and be absorbed into the blood.
- Polymers and must be converted to monomers so they can be rebuilt up into molecules needed by body cells.
What is the process that is propelled along the gut?
By peristalsis.
what are the 4 main functions the human gut performs?
- Ingestion.
- Digestion.
- Absorbtion.
- Egestion.
What are the main parts of the digestive system and what is their function?
- Mouth, ingestion.
- Oesophagus, carriage of food to stomach.
- Stomach, digestion of protein.
- Duodenum, digestion of fats, carbohydrates and proteins.
- Ileum, further digestion and absorption of digested food.
- Colon, absorption of water.
- Rectum, storage of faeces.
- Anus, egestion.
What are the 4 tissue layers surrounding a cavity that the gull wall consists of?
- Serosa, outermost layer of tough connective tissue.
- Longitudinal and circular muscle, responsible for peristalsis.
- Submucosa, connective tissue.
- Mucosa, its epithelium secretes mucus, lubricates and protects.
What is the role of mechanical digestion?
It increases the surface area of food over which enzymes may act to chemically digest the food.
What is the general name given to protein digesting enzymes and what are the 2 main types?
Peptidases.
- Endopeptidases, hydrolyse peptide bonds within.
- Exopeptidases, hydrolyse peptide bonds at the ends.
What prevents the food from leaving the stomach until fully digested?
The pyloric sphincter.
What pits are found in the mucosa of the stomach that secrete gastric juices?
Gastric pits.
What are the 3 types of cells in gastric pits and what’s their function?
- Chief cells, secrete ‘Pepsinogen’ (Inactive).
- Parietal/oxyntic cells, secretes Hydrochloric acid which activates pepsinogen, creates optimum pH for the enzyme and kills pathogenic bacteria.
- Goblet cells, secrete mucus which protects the lining pf the stomach.
What is the function of the liver in the digestive process?
It produces bile containing bile salts, mucus and water. It is stored in the gall bladder and flows along the bile duct into the duodenum.
What is the function of bile salts?
Emulsification of fats. It breaks fats into tiny droplets which increases surface area so that lipase can digest them more readily.
What does saliva contain?
- Amylase, beginning starch digestion.
- Mucus, lubricating the foods passage.
- HCO3 and CO3 ions making it slightly alkali.
What are the 2 regions of the small intestine?
Duodenum and the ileum.
What enzymes does pancreatic juice contain?
- Endopeptidases.
- Trypsinogen (Protein).
- Amylase (Starch).
- Lipase (Lipids).
In humans, why is the ileum adapted to absorption?
- It is very long (6m).
- The lining is folded and on top of these folds are villi and they have microvilli which provide a very large surface area for absorption.
- They have many mitochondria providing energy for active transport.
Where do fat-soluble molecules get absorbed into?
The lacteal.
How is glucose absorbed into the capillaries?
Na+ ions are actively transported out of the epithelial cells into the capillary which creates a concentration gradient. This then causes glucose to move into the epithelial cells by co-transport with sodium down a concentration gradient. Glucose the diffuses across the epithelial cell and then into the capillary by facilitated diffusion.
What are lipids used for in the body?
They’re used in membranes and to make some hormones but excess is stored.
What is glucose and amino acids used for in the body?
- Glucose, respired for energy or stored as glycogen.
- Amino acids, taken to body cells for protein synthesis. Any excess is deaminated in the liver and excreted as urea and stored as fats.
What does the large intestine compromise of?
- Caecum.
- Appendix.
- Colon.
- Rectum.
What in the caecum is secreted by mutualistic micro-organisms living there?
Vitamin K and folic acid.
What is the dentition of herbivores like?
Incisors on the lower jaw only with a leather dental pad on the upper jaw. A gap (Diastema). Molars interlock. The lower jaw moves side to side and the teeth have open unrestricted roots so they continue t grow. It doesn’t need strong facial muscles as its prey is unlikely to escape.
What is the dentition of carnivores like?
They have sharp bones to grip and tear muscle from bone. They have large canine teeth that are curved and pointed for piercing and seizing prey, for tearing muscle and killing.
Sharp molars that cut and crush. Carnassials that shear muscle of the bone. Lower jaw moves vertically to prevent dislocation.
What is a ruminant?
A cud chewing herbivore possessing a ‘stomach’ divided into 4 chambers, the largest of which is the rumen, which contains mutualistic microbes.
How does cellulose digestion take place in a ruminant?
- Grass is mixed with saliva to form cud which passes to the rumen.
- Bacteria in the rumen digest cellulose into glucose and the fermented grass passes to the reticulum where it is re-formed into cud and may be regurgitated for further chewing.
- Cud passes to omasum where water and organic acids are absorbed.
- Abomasum is where protein is digested and then it passes into the small intestine where the products of digestion are absorbed into the blood.
What is a parasite?
They live in or on an organism of another species, the host, and obtain nourishment at the host’s expense., causing some degree of harm and often death.
What is the structure of a pork tapeworm?
The head (Scolex) is made of hooks and suckers. Its body is a linear series of sections called proglottids.
What is the the primary and secondary host for the pork tapeworm?
- Primary, the human.
- Secondary, the pig.
What is the pork tapeworms life-cycle?
The pig becomes infected when its food is contaminated with human faeces. Humans are then infected by eating under-cooked, infected pork.
What adaptations does the pork tapeworm have to enable it to survive in the humans digestive system.
-Suckers and a double row of curved hooks attaching it to the duodenum wall.
-Thick cuticle around the body, protecting it from the humans immune responses.
-The ability to make enzyme inhibitors preventing the host’s enzymes digesting it.
Large surface area to volume ratio so food is absorbed over it’s whole surface.
-No sensory organs, simple excretory and nervous systems but most of the body concerned with reproduction.
-It is a hermaphrodite, allowing vast numbers of eggs to be produced.
-Eggs have resistant shells and survive until being eaten by secondary host.
What is the 3 stages in a head louses life cycle?
- Nits are empty eggs.
- After 1-2 weeks, eggs hatch into nymphs.
- Nymphs become adults after about 10 days and feed on blood which they suck from the scalp of the host.
