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.