B3 Organisation and the Digestive System Flashcards
What are tissues?
A tissue is a group of cells with similar structure and function working together. For example: muscular tissue can contract to bring about movement
What are organs?
Organs are collections of tissues. Each organ contains several tissues working together to perform a specific function
What is the stomach and what is it made of?
Th stomach is an organ involved in the digestion of food.
It contains:
- muscular tissue to churn the food and the digestive juices together
- glandular tissue to produce the juices that break down the food
- epithelial tissue which covers the inside and outside of the organ
What is the pancreas?
The pancreas is an organ that has two functions:
- makes the hormones that control blood sugar
- makes some enzymes that digest food
It contains two different types of tissues to perform these functions
What is an organ system?
An organ system consists of a number of organs that work together to form organisms
What are some examples of organ systems in the human body?
- digestive system
- circulatory system
- gas exchange system
What types of adaptations can we find in organ systems to make them effective as exchange surfaces?
- increased surface area
- rich blood supply
- mechanisms to increase concentration gradient by ventilating surfaces or moving material
- areas with short diffusion distances
What are organelles?
They are smaller parts of cells
What does the digestive system do?
The digestive system is where the process of digestion takes place. This means that the organs in the digestive system break down the large molecules of food into smaller molecules that can be absorbed into the blood.
What are the stages of digestion?
- The food enters into the mouth where it is chewed and saliva is added
- Food then goes down the oesophagus and enters the stomach
- The stomach churns the food and hydrochloric acid is added to break down large insoluble molecules into smaller soluble molecules
- The food now enters the small intestine where digested food is absorbed into the blood stream
- The muscular walls of the small intestine squeeze undigested food into the large intestine. This is were water is absorbed from the undigested food into the blood stream.
- ## The materials left form the faeces. These are stored and then pass out of the body through the rectum and the anus
What is the role of the liver in digestion?
The function of the liver most closely related to digestion is the production of bile, which helps in the digestion of lipids
What are the adaptations of the small intestine to increase diffusion and active transport to the blood?
- It has a very large surface area as it is covered in villi
- good blood supply and short diffusion distance to the blood vessels
What is saliva and what is it used for?
Saliva is a liquid produced by the salivary glands. It contains the enzyme amylase which helps convert starch into maltose
What is the oesophagus?
It is a tube that links the throat with the stomach. It is surrounded by a ring of muscles that contract and relax to push the food down to the stomach. These contracting and relaxing is called peristalsis.
What is the role of the pancreas in digestion?
It produces enzymes (protease, lipase and amylase) that are released in the small intestine to help digest the food
What is the role of the rectum in digestion?
It is where the faeces are stored before they are passed out of the anus
What is the role of the stomach in digestion?
The food stays in the stomach for 4 to 5 hours. Here it is mixed with an enzyme, pepsin, that breaks down the proteins contained in it. The stomach also produces hydrochloric acid, which helps kill bacteria and has a ph of 2 , which creates the correct conditions for protease enzymes.
What are the 7 nutrient groups?
Carbohydrates Proteins Fats and Oils Minerals Vitamins Fibre Water
Where are carbohydrates found and what are they used for?
Found in: bread, pasta, cereals, rice, potatoes, cakes
Used for: they are broken down to glucose which is used as source of energy
Starch and Sugars are two forms of carbohydrates
Where are proteins found and what are they used for?
Found in: egg, meat, fish, nuts, dairy products, milk, pulses, cheese
Used for: needed to make new cells and tissues in the body. Essential for growth and repair. They are also the basis of all enzymes
You find them in hormones such as insulin and in atibodies.
Where are lipids found and what are they used for?
Found in: butter, cake, red meat, cheese, crisps, oils, cream
Used for: stored as energy reserve and provide insulation
What are carbohydrates, lipids and proteins?
They are the main compounds that make up the structure of a cell
What chemical elements do carbohydrates contain?
They contain carbon, oxygen and hydrogen
What are carbohydrates made of
They are made of units of sugars
What are simple sugars?
Simple sugars are small carbohydrate units which contain either only one unit of sugar (ex. glucose C6H12O6) or two units (ex. sucrose what we call sugar)
What are complex carbohydrates?
Complex carbohydrates (ex starch and cellulose) are made of of long chains of single sugars bonded together
What is the carbohydrate cellulose?
It is an important support material in plants
What are lipids made of?
Lipids are made of carbon, hydrogen and oxygen
What are types of lipids?
Fats (solid) and oils (liquid)
What molecules make up lipids?
Three molecules of fatty acids joined to a molecule of glycerol.
The glycerol is always the same but the fatty acids vary. Depending on which fatty acids the lipid will be solid or liquid.
Of what elements are proteins made up of?
Carbon, hydrogen, oxygen, nitrogen
What is a protein molecule made up of?
A protein molecule is made up of long chains of small units called amino acids
How many different amino acids are there?
20
What do different arrangements of amino acids lead to?
Different proteins
How are the chains of amino acids aranged
They are folded into 3d shapes
What are the bonds that hold proteins together sensetive to?
Ph level and temperature
How do you identify carbohydrates using food tests?
- iodene test for starch: yellow/ red iodene solution turns blue/black if starch is present.
- benedict test for sugars: blue solution turns brick red on heating if sugar is present.
How do you identify protein using food tests?
-Biuret test: blue biuret reagent turns purple
How do you identify lipids using food tests?
-Ethanol test : cloudy white layer if a lipid is present
What is a catalyst
A catalyst speeds up a reaction without bring used up
What are enzymes
They are biological catalysts that speed up reactons.
They are large protein molecules.
What do enzymes interact with?
Each enzyme interacts with a particular substrate
Why is the shape of an enzyme important?
enzymes can only bind to certain substrates. The active site has a certain shape so only that type of substrate molecule can bond to the enzyme.
What is the lock and key theory?
That only certain molecules can fit in the acive site of an enzyme much like only one key can fit in a lock.
What is metabolism and what is it controlled by?
Metabolism is the sum of all the reactions in a cell or in the body. It is controlled by enzymes.
What are the different types of metabolic reactions?/ what are enzymes involved in?
-Biulding new molecules
Eg: biulding starch, glycogen or cellulose from glucose; lipids from fatty acids or proteins from amino acids.
-changing one molecule into another
Eg:changing one simple sugar into another and converting amino acids
-breaking down molecules
Eg: during digestion
How does temperature affect enzyme action?
- temperature speeds up chemical reactions even when a catalyst is present
- For mot organisms if the temperature exeeds 40 degrees the active site will change and the substrate will no longer fit. The enzyme is said to have been denatured. It can no longer act as a catalyst so the reaction slows.
Why is it important that your enzymes don’t exeed 40 degrees?
Enzymes need to react fast enough. If they are to slow to react you will die
- if the active site changes they will react slower and you will die
Anomolise amongs enzymes?
Some enzymes can function above 80 degrees and some can function below 0
How does PH level affect enzyme action?
Enzymes only opperate on a certain ph level
The shape of the active site of an enzyme comes from forces between
the different parts of the protein molecule. These forces hold the folded
chains in place.The ph level affects these forces thats why a stable ph level is important.
What is enzymes activities affected by?
Temperature and PH
What does high temperature do to enzymes and the active sites?
It Denatures the enzyme and change the shape of the active site
What effect does PH have on enzyme and shape of active site
It can make the enzyme work either efficiently or inefficiently and can affect the shape of the active site
What does digestion involve?
It involves breaking down large , insoluble molecules into soluble substance that can be absorbed by the blood
Where are digestive enzymes produced?
They are produced in specialised cells called glands in the lining of the digestive system
What catalyst is used to break down carbs?
Amilase breaks down carbs into simple sugars
What catalyses the break down of proteins?
Proteases catalyse the break down of proteins turning them into amino acids
Where are proteases produced?
Stomach, small intestine and pancreas
Where does the break down of proteins take place
stomach and small intestine
What catalyses the breakdown of lipids?
Lipases catalyses the break down of lipids into fatty acids and glicerol
Where are lipase made
Pancreas and small intestine
Where is amylase produced?
pancreas and salivary glands
Where is hidrochloric acid produced and what is it for?
It is produced in your stomach and it allows the protease enzymes to work efficiently and also kills most of the bacteria in your food. It gives the stomach a low PH
What is the mucus produced by your stomach used for?
to protect the lining of the stomach from being attached by the acids
What happens when someone develops a ulcer
The mucus is lost and the acid and enzymes attack the lining
What environment do digestive enzymes work best in?
Alkaline
What is bile?
Bile is an alkaline liquid that makes the acids produced by the stomach alkaline. It is produced by the liver and it is stored in the gull bladder. It neutralises acids and gives a high PH for the enzymes of the pancreas and small intestine to work well
How does bile work?
When food reaches the small intestine the bile is squirted from the bile duct and neutralises the acids
Despite neutralising acids what is bile other important use?
It emulsifies large drops of lipids into smaller drops so that the lipase can break down the fats quicker
What can gall stones do?
Block the bile duct and gall bladder having an impact on digestion and cause pain
