Topic 2: Organisation and Digestion

How are cells organised

Cells are the basic building blocks that make up all living organisms. Specialised cells are organised to form tissues, which form organs, which form organ systems

Tissues

Definition = A tissue is a group of similar cells that work together to carry out a particular function

A tissue can include more than one type of cell. Mammals (like humans), have several different types of tissue

Organs

Definition = An organ is a group of different tissues that work together to perform a certain function

Mammals have many different organs, which are made up of different tissues

Organ Systems

Definition: An organ system is a group of organs working together to perform a particular function

Rearrange from smallest to largest:

whole body, cell, tissue, organ system, organ

Cell, tissue, organ, organ system, whole body

Different tissues

• Muscular tissue - contracts (shortens) to move whatever it’s attached to

• Glandular tissue - makes and secretes substances like enzymes

• Epithelial tissue - covers some parts of the body eg the inside of the gut

• Connective tissue - binds, supports, and protects other tissues and organs eg bone, fat, blood, cartilage

• Nervous tissue - generates and transmits electrical signals, allowing for communication between body parts eg brain, spinal cord

Tissues that make up organs

Stomach:

• muscular tissue, which moves the stomach wall to churn up the food

• Glandular tissue, which makes digestive juices to digest food

• Epithelial tissue, which covers the outside and inside of the stomach

Heart:

• nervous tissue, which regulates heart rate

• connective tissue, which is for structure and valves

Skin:

• epithelial tissue (epidermis)

• connective tissue (dermis)

Different organ systems

• Excretory system - liver, bladder, kidney (removes waste products from the blood)

• Circulatory system - arteries, veins, heart (pumps blood to transport oxygen and nutrients)

• Respiratory system - trachea, bronchi, lungs (oxygen and carbon dioxide)

• Nervous system - brain, spinal cord (controls body actions and detects sensations)

• reproductive system - testes/ovaries, uterus (produces offspring)

Circulatory System Function

Is to transport substances throughout the body, including oxygen, nutrients and hormones while also removing waste products like carbon dioxide

Respiratory System Function

Is to take in oxygen from the air we breathe and remove carbon dioxide from the body

Excretory System Function

Is to remove toxic waste from the body through processes like urination and sweating, while also regulating water balance

All the organs in the digestive system

• Mouth

• Oesophagus

• Stomach

• Pancreas

• Small intestine

• Large intestine

• Rectum

Mouth Function

Releases amylase made by salivary glands which breaks down starch (teeth increase surface area)

Oesophagus Function

Transports food from the throat to the stomach through a process called peristalsis

Stomach Function

Mixes food with enzymes and acids

What does the stomach make

makes protease, breaks down proteins into amino acids

Pancreas Function

Produces insulin used to control blood sugar levels

What does the pancreas contain

contains the enzymes:

• protease

• amylase

• lipase

and puts them into the small intestine

Small intestine Function

uses all enzymes to break down remaining protein/carbohydrate (contains villi)

Large intestine Function

absorbs water from undigested food, and to absorb vitamins

Rectum Function

Acts as a storage area for feces before they are eliminated from the body

Kidneys Function

Involved in excretion and the production of urine

Gall bladder Function

Stores bile

Liver Function

Produces bile

Bile duct Function

Transports bile

Testes Function

Produce sperm and testosterone

Anus Function

Releases waste

Why is the heart defined as an organ

Because the muscle, blood and elastic tissue work together

Processes of the digestive system

• Assimilation

• Peristalsis

• Egestion

• Digestion

• Ingestion

Assimilation

The process of moving digested food molecules from the bloodstream into cells where they are used for energy growth + repair

Peristalsis

The process of squeezing food to stomach

Egestion

The process of expelling undigested food and other waste materials from the body

Digestion

The process of breaking down food

Ingestion

The process of taking food or drink into the body

Starch Food Test

Iodine solution - —

Starch present - —

Starch not present - —

Starch is found in:

• bread, biscuit, cake

Starch is needed for:

• slow releasing energy

Sugar (glucose) Food Test

Benedict’s solution - —

A little glucose present - —

Lots of glucose present - —

Glucose not present - —

Glucose is found in:

• apples

Glucose is needed for:

• quick release energy

Fat Food Test

Ethanol - — (clear)

Fat present - —(cloudy layer)

Fat not present - — (clear)

Fat is found in:

• cheese, fat

Fat is needed for:

• warmth, protection, emergency energy

Protein Food Test

Biuret Solution - —

Protein present - —

Protein not present - —

Protein is found in:

• chicken, cheese

Protein is needed for:

• growth + repair

Food Test Results

What are minerals, vitamins and fibre needed for

Minerals - Bodily Function

Vitamins - Maintain boy function

Fibre - Keep regular

Enzymes

• Living things produce enzymes which are proteins which act as Biological Catalysts

• This means that they speed up a reaction in living things, but are not used up themselves

• They are also affected and damaged in certain conditions

What are proteins made up of

Chains of amino acids. These chains are folded into unique shapes, which enzymes need to do their jobs

What are enzymes made from and what do they break down

• made from: amino acids

• Break down: carbs, proteins and lipids

Why enzymes are needed for digestion

• They are proteins that speed up the breakdown of large food molecules into smaller, simpler, and more absorbable ones that the body can use

• Without enzymes, the reactions that break down food would be too slow for the body to absorb the nutrients needed for energy, growth + repair

Enzyme Structure

• The enzyme has a specific-shaped active site

• Which is a complementary shape compared to the substrate

• Substrate fits into it like a lock + key

Active Sites

• Every enzyme has an active site with a unique 3D shape that fits onto the substance involved in a reaction

• Enzymes only catalyse one specific reaction. This is because, for the enzyme to work, the substrate has to fit into its active site. If the substrate doesn’t match the enzyme’s active site, then the reaction won’t be catalysed

Denatured definition

Active site changes shape so no longer complimentry

Why might enzymes need a unique 3D structure

So it is complimentry to the substrate

Why the shape of the enzyme is vital for it to function

• The active site has a unique 3D shape that is complementary to the shape of a specific substrate; only the correct substrate can fit into the active site

• If the enzyme’s shape changes due to the temperature or PH the active site will no longer match the substrate, and the enzyme will lose its function

Lock and Key theory explanation

• The substrate binds the active site of the enzyme to form the enzyme-substrate complex

• The enzyme breaks down the substrate into products

• The substrate and the enzyme’s active site are specific to one another

Two key things that can affect the activity of enzymes

• Temperature - Changing the temperature changes the rate of an enzyme-catalysed reaction. A higher temperature increases the rate, but if it gets too hot, some of the bonds holding the enzyme together break, which changes the shape of the enzyme’s active site, so the substrate won’t fit anymore, so the enzyme is denatured.

• PH - If it’s too high or too low, the PH interferes with the bonds holding the enzyme together. This changes the shape of the active site, so the enzyme is denatured

What temperature and PH do enzymes work best

Temperature - 37 degrees

PH - 1-2

What are carbohydrates, lipids and proteins used for

• Carbohydrates - used for energy

• Lipids - used for energy storage, insulation and protection

• Proteins - used for growth and repair

Why do we need to break down carbohydrates, proteins and lipids

They are big molecules, so they are way to big for us to absorb into our bloodstream across the villi of our small intestine

What are carbohydrates

• Carbohydrates are a group of biological molecules that are used for energy in the body

• The individual molecules are glucose, but together they make starch

How the breaking down of carbohydrates works

To break starch down, we use the enzyme Amylase, which breaks it into maltose molecules, and then the enzyme of maltase breaks the maltose down into glucose, which is now small enough for us to absorb

Carbohydrates Structure

Carbohydrase (Lock + Key theory)

Carbohydrates

• Enzyme that acts on it

• Which products are formed

• Where it is produced

Amylase

Maltose

Salivary glands

Pancreas

Small intestine

What are proteins

Proteins are a group of biological molecules that are used for growth and repair

How the breaking down of proteins works

• They are broken down by protease enzymes into amino acids (there are lots of different amino acids)

• Protease = A group of enzymes: trypsin, pepsin

Proteins Structure

Protease (Lock + Key theory)

Proteins

• Enzyme that acts on it

• Which products are formed

• Where it is produced

Protease (pepsin + Trypsin)

Amino Acids

Pancreas

Small intestine

Stomach

What are lipids

Lipids are a group of biological molecules that are used for energy storage, insulation and protection

How the breaking down of lipids works

• They are broken down by Lipase enzymes into smaller molecules called glyceral and fatty acids

• Bile also helps in the breakdown of lipids, it can take big droplets of lipid and break them up into lots of little droplets which increases the surface area

Lipids Structure

Lipase (Lock + Key theory)

Lipids

• Enzyme that acts on it

• Which products are formed

• Where it is produced

Lipase

Fatty acuds

Gylcerol

Pancreas

Small intestine

Functions of Bile

• Emulsifies fat to form small droplets, which increases the surface area. The alkaline conditions and large surface area increase the rate of fat breakdown by lipase.

• Neutralise the acid from the stomach (the other enzymes in the intestine would denature)

calculate the mean rate of an enzyme-catalysed reaction

1000/Time

Monemer + Polymer

• Monemer (glucose) = 1

• Polymer (starch) = lots

The difference between a qualitative and a quantitative test

Qualitative = yes or no?

Quantitative = how much?

What is the amylase in the mouth called

Salivary amylase

Pancreatic Amylase

• From

• Where in the body does it work

Pancreas

Intestine

Pepsin

• Where in the body is it found

• What would happen if it was placed in alkaline conditions

Stomach

Denature