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