Nutrition and Digestion Topic 5 1st year Flashcards
What is nutrition?
Nutrition is the way by which an organism processes nutrients to obtain energy for respiration, growth and repair.
There are 2 types of nutrition. Mention and explain them.
Autotrophic and heterotrophic
Autotrophic: Organisms which build up their own food from inorganic molecules like plants carry out photosynthesis or some types of bacteria
Heterotrophic : organisms which are unable to synthesize their own food They obtain ready made food which has been synthesized from autotrophs.
(Feed on sources of carbon)
What is holozoic nutrition?
Applied mainly to animals which have a digestive tract called the alimentary canal
Which animals are holozoic and why are they holozoic?
Carnivores
omnivores
herbivores
Most animals are holozoic because they ingest the food and break it down by enzyme action. The unwanted wastes are then egested
Define carnivores, omnivores and herbivores
Carnivores:organisims which feed only on meat like lions or dogs
Omnivores: organisims which feed on both meat and plants like: bears or humans
Herbivores:organisims which feed on plants only. like deer or cows
What are parasites?
Living organisms which feed on other living hosts and cause them harm
ex: lice or tapeworm
What are decomposers/saprophytes?
Organisms that obtain their food from dead decaying organic matter. ex: some bacteria and fungi.
They mainly focus on breaking down dead decaying organims
What are detritivores?
Detritivores are living organisms which feed on small organic debris generally left by saphrotrophs.
These are also decomposers. So they help saphrophytes
Why cant food be absorbed directly in heterotrophic organisms?
Because food consists of large insoluble food molecules which are too complex and first need to be broken down by mechanical and chemical digestion into simpler and soluble food molecules to be able to be absorbed by the body.
What are the 2 types of digestion?
Mechanical and chemical
Define digestion.
Digestion is the breakdown of large insoluble food molecules making them into small soluble food molecules so that they can be absorbed in the bloodstream. This si done by mechanical and chemical digestion
True or false.
The body cannot absorb food directly because the food first needs to be broken down into simpler substances
True
How are carbohydrates, lipids and proteins absorbed in the body?
carbohydrates:simle sugars
lipids: glycerol and amino acids
proteins: amino acids
True or false.
Simple substances like vitamins ,mineral and water also need to be broken down.
False.
If they are simple substances they do not need to be broken down because they are already in a usable form that the body can absorb.
Define the alimentary canal.
A long coiled and muscular tube which runs from the mouth to the anus. Food is taken in and ingested through the mouth, wastes are egested through the anus. The alimentary canal is specialized to perform different functions
What are the different steps of digestion along the alimentary canal?
Ingestion
Digestion
Absorption
Assimilation
Egestion
Define ingestion.
The act of taking complex organic food into the alimentary canal through the mouth
Define absorption
The process where digested food molecules passes from the alimentary canal through the bloodstream. It involves the uptake of soluble food molecules into the bloodstream across a cell membrane
Define assimilation
Assimilation is the use of soluble food molecules by cells in the body. It consists of the incorporation of digested food molecules into all the cells of the body.
For example amino acids are built up into proteins
Define egestion
The removal of undigested food from the alimentary canal(from the body)
Distinguish between intracellular and extracellular digestion
Intracellular digestion: in simple organisms like amoeba, digestion takes place inside the cell. Soluble food is absorbed directly into the cytoplasm of the cell. Indigestible material is egested
Extracellular digestion: food enters the alimentary canal, then the food is broken down by enzyme action (digestive enzymes are released along this tube),after soluble food molecules can be absorbed into the bloodstream through a cell membrane. It is known as extracellular digestion because it is taking place outside of all the cells in the body.
True or false.
Enzymes are always in an active form
False.
Enzymes are inactive and then they are changed into active catalysts
What would happen if enzymes in the stomach are always active? How does the stomach protect itself?
If enzymes in the stomach are always active then ulcers could form, but this doesn’t happen because the stomach produces mucous
What is a macromolecule?
A large molecule consisting of repeated subunits called monomers.
In digestion ,it needs to be broken down to form a micro molecule
What are digestive reactions in the body called?
Catabolic reactions and they are usually hydrolysis reactions involving hydrolytic enzymes (addition of water)
In the body there are different enzymes which are specialized to break different substrates. Mention the types of substrates that these enzymes act upon: proteases,lipases,carbohydrases,amylases,nucleases and peptidases.
Proteases: proteins ex:trypsin or
Lipases:lipids : lipase
carbohydrases: carbohydrates: sucrase,maltase,lactase
nucleases: nucleic acids
amylases: starch (salivary amylase)
peptidases: break down polypeptides
What is an epithelium?
1 layer of cells, which are continuously being replaced by worn out cells
Draw a diagram of the alimentary canal
Know how to label the parts of the digestive system
Distinguish between mechanical and chemical digestion
Mechanical: also known as physical. This involves breaking food into small pieces by chewing it and churning it up with no chemical change. It involves breaking down food physically
Chemical digestion: the breakdown of large molecules into smaller ones by water and digestive enzymes. Large molecules are made into smaller and simpler forms
Since enzymes are made in cells, where are enzymes stored in the digestive system?
In glands (extracellular enzymes)
What can we also call the mouth?
The buccal cavity
What happens when food is ingested through the first part of the alimentary canal?
Digestion takes place in the mouth first. The mouth contains a neutral ph of 7
Both mechanical and chemical digestion are taking place inside of the mouth.
Mechanical digestion: teeth are present. Chewing takes place which involves breaking down the food into smaller fragments which also increases the surface area for the enzymes to work
Chemical digestion: saliva and water (mucous) are present which contains salivary amylase produced by salivary glands
Mention some functions of saliva.
Lubricates the food for swallowing
Dissolves soluble food
Contains the enzyme salivary amylase, which changes starch into maltose
What is the wet and food “ball” called which has been made in the mouth during the first part of digestion by mechanical and chemical digestion?
Bolous
How is the food swallowed and pushed back so it can reach the oesophagus?
The tongue helps to lubricate the food and it is pushed back.
A muscle flap called the epiglottis closes the trachea during swallowing. This prevents the bolous from reaching the lungs and prevents choking.
What closes the nasal passage during swallowing?
The soft palate
After swallowing where does the bolous go?
Oesophagus
The oesophagus is a pipe which connects the mouth to the stomach.
What makes it easier for the bolous of food to go down the oesophagus?
Peristalsis
Mucous and saliva.
They act as a lubricant to help the food go down the gullet easily
What is peristalsis?
Since the walls of the gullet are made of muscle, a ring of muscular motion and contraction moves downwards which helps the bolous go down the stomach
What are the muscles in the oesophagus called?
Circular and longitudinal muscles
When the circular muscles contract the longitudinal relax and vice versa
What is the role of teeth during digestion and why is this important?
Teeth break down food into smaller fragments. This increases the surface area for the enzymes to work properly
Mention the 4 types of teeth
Incisors
Canines
Premolars
Molars
Mention the structure and function of each tooth.
Incisors: located at the front of the mouth,chisel-shaped and are responsible to cut and bite food.
Canines: located behind the incisors,pointy shaped and are responsible to tear ,pierce and grasp the food
Premolars: located behind the canines, flattened with cusps and are responsible to grind and crush food
Molars: located behind the premolars,flattened with cusps and are also responsible to crush and grind food