Nutrition Flashcards
What is autotrophic nutrition?
Simple inorganic molecules built up into complex organic molecules
What is photoautrophic nutrition?
Organisms that use light energy to convert simple inorganic molecules into complex organic ones.
.Chlorophyll is used to absorb sunlight energy
What is an example of an organism that uses photoautrophic nutrition?
Green plants, such as Dandelion, Algae and certain bacteria
What is chemoautrophic nutrition?
.Use the energy derived from special methods of respiration (such as the oxidation of hydrogen sulphide/ sulphur/ ferrous ions or nitrates) to convert simple inorganic molecules into complex organic ones.
What is an example of an organism that uses chemoautotrophic nutrition?
Bacteria eg nitrosomonas
Define heterotrophic nutrition?
Complex organic molecules broken down to release energy (consumers)
How does digestion work in holozoic feeders ?
Food is processed as it passes along the gut
How does the structure of the gut differ between simple organisms that eat one type of food and more complex organisms?
Simple organisms have a undifferentiated gut, where as advanced organisms with a varied diet have a divided gut
Why are complex organisms gut divided?
Allows for specialisation for specific functions like, ingestion, digestion, adsorption and egestion.
What do saprotrophs/ saprobionts feed on?
Dead or decaying matter
What organisms are classed as saprotrophs/ saprobionts?
All fungi and some bacteria
What type of digestion do saprotrophs/ saprobionts carry out?
Extracellular
What is extracellular digestion?
When enzymes are secreted onto food outside the body then soluble products of digestion are adsorbed by diffusion across the cell membrane.
Describe the process of fungal feeding?
- Fungi secrete enzymes from the growing tip of the hyphae which penetrates the food to secrete the enzymes.
- The enzymes diffuses out through the cell membrane and cell wall onto the surface of the food (Substrate)
- These enzymes digest the food into soluble products
- These soluble products are the absorbed into the hyphae through the cell wall and cell membrane by facilitated diffusion or active transport.
- The soluble products are transported within the fungi and excess are stored
- This is extracellular digestion
What is a parasite?
An organism that feeds on or in another organisms (host)
Where do parasites live?
On or in the host
What happens to the host of a parasite?
Harm or death
What is the case study example for parasites?
Tapeworms
What is mutalism?
Also known as symbiosis and involves a close association between members of two different species.
(When two different species rely on each other for survival)
Why do different parts of the human gut have different pH values?
Different enzymes have different optimum pH
What type of feeder is amoeba?
Amoeba which are protocista are holozoic feeders
Describe the structure of amoeba?
They are a single celled organisms with a large surface area to volume ratio
How do amoeba obtain their nutrition?
They obtain their nutrients by diffusion, facilitated diffusion or active transport across their cell surface membrane
How do amoeba take in larger molecules?
By endocytosis, which in turn fuse with lysosomes so that the contents can be digested
What happens to the products of digestion in amoeba?
The products of digestion are absorbed into the cytoplasm and ingestible material is egested by exocytosis.
What is ingestion?
Large food particles are taken into the buccal cavity
What is Mechanical Digestion?
The action of teeth, saliva and the tongue (mastication) so it may then move into the gut
What is chemical digestion?
The chemical breakdown (enzymes) of large insoluble molecules to small, soluble molecules. (Different regions of the gut have different pH therefore the enzymes found in the different regions have different pH optima)
What is absorption?
Small, soluble food molecules move from the small intestine into the blood stream.
What is the serosa and what is its function?
Tough connective tissue covered by squamous epithelium that protects the wall of the gut and reduces friction from other organs in the abdomen as the gut moves during the digestive process.
What is the Muscle layer and what is its function?
Circular and longitudinal muscle, cause waves of muscular contractions, peristalsis which propels food along the gut. Behind the food the circular muscles contract and the longitudinal muscle relaxes.
What is the sub-mucosa and what is its function?
Connective tissue containing blood and lymph vessels to take away absorbed food products as well as nerves that co-ordinate the muscular contractions of peristalsis.
What is the Mucosa and what is its function?
The innermost layer (epithelium) that lines the walls of the gut. It secretes mucus from goblet cells which lubricates and protects the mucosa. In some regions it secretes digestive juices in others it absorbs digested food.
What are the 3 main forms of mechanical digestion?
.Crushing action of teeth
.Action of stomach
.Peristaltic action of muscular layers in gut wall
What is the purpose of mechanical digestion?
Mechanical digestion increases surface are of food over which enzymes may act to chemically digest the food.
What is chemical digestion?
The use of enzymes to hydrolyse large insoluble molecules into smaller soluble molecules.
What is the role of endopeptidase?
Hydrolyse peptide bonds within a molecules
What is the role of exopeptidase?
Hydrolyse peptide bonds at the ends of shorter polypeptide bonds
What component of saliva maintains the slightly alkali conditions?
Mineral salts
What is the optimum pH for the buccal cavity?
pH of 6.5-7.5 is optimum for salivary amylase
What enzyme is produced in the saliva?
Salivary amylase, which converts start into maltose
What is the function of mucus?
Acts as a lubricant and protects the gut wall
What occurs in the oesophagus?
The bolus moves to the stomach by a aeries of rhythmic contraction called peristalsis
What is pepsin secreted as and why?
Pepsinogen so it doesn’t cause digest the secretory organ
What are the three roles of hydrochloric acid?
- Kill bacteria
- Provides optimum pH for enzymes
- Activates pepsinogen into pepsin
What is the pH of the stomach?
pH 1-2
Where secretes mucus in the stomach?
Goblet Cells
What is the role of mucus in the gut?
- Protects the lining of the stomach cells from the acid and pepsin by neutralising it.
- Aids movement of food within the stomach
- Mucus is alkaline due to the presence of hydrogen carbonate salts
What cells secrete pepsinogen?
Chief cells (peptic)
What type of cells secrete Hydrochloric acid?
Parietal (oxyntic)
Where do digestive secretions occur outside the gut?
- Salivary gland (saliva)
- Pancreas (pancreatic juice)
- Liver (bile)
Where do digestive secretions occur in the wall of the gut?
- Gastric glands (stomach mucosa) produce gastric juice
- Brunner’s Glands in the sub-mucosa of the duodenum secrete alkaline juice, enterokinase and mucus into the small intestine.
Where are enzymes found/ released?
.Released from secretory cells at the tip of the villi
.Embedded in the cell membrane
.In the cytoplasm of the epithelial cells in the mucosa
What does maltose hydrolyse?
Maltose into glucose
What does sucrase hydrolyse?
Sucrose into glucose and fructose
What does lactase hydrolyse?
Lactose into glucose and galactose
What do exopeptidase hydrolyse?
shorter polypeptide chains into amino acids
What does dipeptidase hydrolyse?
Dipeptides into amino acids
How is maltase released and used in the ileum?
Maltase is embedded in the membrane of the epithelial cells of the ileum, and hydrolyses maltose into glucose
How is dipeptidase released and used in the ileum?
It is embedded in the membrane of the epithelial cells of the ileum, it hydrolyses dipeptides into amino acids.
What are the adaptations of the ileum for absorption?
.Very long (5m)
.Folded lining
.Lining is covered in villi
.Each villi is covered in microvilli, also known as the brush border
What is the purpose of the villi and microvilli?
They provide a large surface area for enzyme activity and absorption
Why do the epithelial cells of the ileum contain many mitochondria?
Absorption is active so ATP is required which mitochondria synthesises.
What is the muscularis mucosa?
A thin layer of muscle under the mucosa, smooth muscle which contracts for a long period of time without tiring.
What is the function of the muscularis mucosa?
The contractions move the villi, allowing greater contact with food and therefore more efficient absorption.
What catalyses the breakdown of starch into maltose?
Amylase
What hydrolyses proteins into polypeptides?
Endopeptidase
What hydrolyses polypeptides into dipeptides?
Exopeptidase
What hydrolyses dipeptides into amino acids?
Dipeptidase
What hydrolyses lipids into emulsified lipids?
Bile Salts
What hydrolyses emulsified lipids into fatty acids and glycerol?
Lipase
Where is digested food absorbed?
In the ileum
What is absorbed by the plasma membrane of the epithelial cells of the vili in the ileum? (6)
- Monosaccharides
- Amino acids
- Fatty acids
- Glycerol
- Minerals
- Vitamins
How are water soluble molecules absorbed in the ileum?
Absorbed into the blood capillaries
How are fat soluble molecules absorbed in the ileum?
Absorbed into the lacteals of the lymphatic system
How are molecules absorbed in the ileum?
- Facilitated diffusion
- Passive diffusion
- Active Transport
How are remaining disaccharides broken down in the ileum?
By intracellular digestion
What are the four steps to glucose absorption? What ion is used?
- Na+ are actively transported out of the epithelial cells
- This creates a low concentration of Na+ inside the cell
- Na+ moves into the epithelial cell from the lumen of the ileum by co-transport with glucose
- Glucose moves by facilitated diffusion from a high concentration inside the epithelial cell to a low concentration in the capillaries.
How are lipids absorbed in the ileum?
As glycerol and fatty acids
What is a lacteal?
A lymph capillary found in the centre of each villus, which leads into the lymphatic system, which opens into the bloodstream at the thoracic duct.
What happens to glucose absorbed in the digestive system?
Absorbed from the blood by cells and used in respiration. Excess glucose is converted to glycogen or fat for storage.
What happens to Lipids that are absorbed in the digestive system?
These are used to produce phospholipid[ids in cell membranes, hormones or excess stored as fat.
What happens to Amino Acids that are absorbed in the digestive system?
Absorbed by cell for protein synthesis. Excess cannot be store so is converted into urea for excretion. (Animation)
What is the function of the colon in water absorption?
The large intestine absorbs the remaining water, with vitamin K and folic acid
How is folic acid produced?
It is synthesised by the gut bacteria
What is the function of the large intestine (colon)?
To produce solidified faeces
What 3 things pass out of the digestive system with the faeces?
- undigested cellulose
- Bacteria
- Sloughed off cells
What is the function of cellulose in the diet?
Bulks the faeces and stimulates peristalsis.
