Biology - Human nutrition
What is Peristalsis
*The process by which food if moved through the gut* 1. This is the contractions of two sets of muscles in the walls of the gut (all the way down the alimentary canal) 2. One set runs along the gut, 3. while the other set circles it. 4.Their wave-like contractions create a squeezing action, moving BOLUSES through the gut. 5. Boluses - food ball *WAVES OF CIRCULAR MUSCLES CONTRACTIONS*
Types of digestion + what is it
- The break down of large insoulble molecules into smaller soluble molecules 1. Mechanical - teeth and stomach muscles 2. Chemical - Enzymes and bile
What is bile + where produced
-) Produced in the liver and stored in the gall bladder before being released into the small intestine -)The hydrochloric acid in the stomach makes the pH too acidic for the enzymes in the small intestine to work properly. Bile is Alkaline - it neutralists the acid and makes alkaline. -) Bile takes big globs of fat and EMULSIFIES them - breaks it ip for larger SA for enzymes to get to it quicker so faster digestion -) Rember the bile does not actually change anything just makes the fat smaller
What is lipase + where i sit produced
-)The enzyme that breaks down fat into fatty acid and glicerol -) Produced in the pancreas (goes to small intestine...?)
What will increasing the temperature do do an enzyme reaction.
1. At first it will increase the rate of reaction. This because heat means the enzyme substrate particles have more energy. This means the enzymes and the substrate particles move about more, so they're more likely to meet up and react. - they have a high COLLISION RATE 2. However, if it gets too hot the bonds holding the enzyme together will break and the active site will become denatured, or misshaped so the substrate cannot fit in the molecule ( this is perms tote)
How can you investigate the effect of temperature on enzyme activity- Measure how fast a substrate disappears
1. Beaker in water bath at constant temperature (hot then cold) 2.In the beaker put a solution of starch and amylase 3. Drop the solution using a dropping pipette onto a spotting tile with iodine in it. 4.When the iodine solution is no longer blue black all the starch has been broken down by the amylase 5. Time how long this^^ takes and compare the different temperatures.
What variable goes on what axis
1. Dependent -y 2. Independent - x
What can denaturing do depending on question asked
1. EIther stop the enzyme speeding up the reaction (say this if it asks why the reaction is very slow ) 2. The substrate can fit to the active site so the reaction stops (asks why the rate of reaction is zero at 45°c)
Why is the stomach acidic
1. For bacteria to be killed 2.Optimum PH for proteases to work.
Effect of PH on enzymes
1. If it's too high or too low, the PH interferes with the bonds holding the enzymes together - this changes the shape of the active site and denatures the enzyme
What are the stages of digestion
1. Ingestion 2. Digestion 3. Absorption 4. Assimilation 5. Egestion
Sturtcure of the stomach
1. It is the only place in the body with three layer of muclse 2. There is a mucous membrane inside 3. The esophagus leads into the stomach 4. The duodenum leads out of the stomach
How can you investigate the effect of temperature on enzyme activity
1. Meaure how fast a product appears at different temperatures 2.
How do contraction in the stomach assist in the chemical break down of food
1. Mixes up acid/protease in with all the food 2. Mixes it up 3.It increases the chance of enzymes hitting where it needs to hit (the food!)
Describe one way which can ensure results are precise as possible and one think that can cause an anomalous result
1. Smaller increments of measurements on measuring cylinder 2. Human error such as reading the scale on the measuring scale right
What do you need to put for questions of designing and investigation
1. State what you would measure and how to measure it 2. State dependent and independent variables variables 3. State controlled variables and how you would control certain variables you need to control (e.g saying starch needs to stay at the same temperature of using the same batch of amylase for each experiment)
What muscles are involved in Peristalsis
1. The circular muscles (circle around the wall of the gut) 2. The longitudinal muscles (run along the wall of the gut)
Description of an enzyme reaction
1. The enzyme has an active site of a certain shape 2. The substrate is the molecule that is changed in the reaction 3. The substrate is a specific shape and fits into the active site - this is called a lock and key model * a substrate has to be the correct shape to fit into the active site
What happens to rate of enzyme reaction if you decrease Temperature:
1. There is a lower collision rate and therefore a slower reaction
What is absobed into the blood capillaries
1. glucose 2. amino acids 3. vitamins 4. Minerals
What is teh function of the large intestine
1. re absorption of excess water from food (diarrhea = large intestine is not doing its job!)
Mouth
1. the first part of the digestive system, where food enters the body. Chewing and salivary release (contain amylase enzyme) in the mouth are the beginning of the digestive process (the breaking down of food). 2. Teeth break down food mechanically increasing surface area for enzyme to work on
What is a metabolic reaction + what would decreasing the rate of it do
1.A metabolic reaction is one of the chemical processes that occur in living organisms in order to maintain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. 2. Decreasing the temperature will decrease the rate of enzyme catalyst reactions so the metabolic reactions will be slower and the rate of reproduction of cells will decrease
Optimum ph of pectin
2 -all enzymes have an optimum PH that they work best at.
What is the optimum Temperature for enzymes
37 - body Temperature!
Trypsin optimum ph
7
What is the function of the Liver + where is it?
A large organ located above and in front of the stomach. It filters toxins from the blood, and makes bile (which emulsifies fat) and some blood proteins.
Describe + what happens in... The Stomach
A sack like muscular organ that is attached to the oesophagus. 1.When food enters the stomach it is churned in an acid bath (hydrochloric acid) 2. It produces a protease enzyme, pepsin
Appendix
A small sac located near the start of the large intestine - pretty much useless
Gall bladder
A small, sac-like organ located by the duodenum. It stores and releases bile (a digestive chemical which is produced by the liver) into the small intestine
What pH do enzymes in the small intetine work best at
Alkaline condition!
What enzyme breaks down starch, into what and where
Amylase(primarily) breaks down starch (carbohydrate) into Maltose and Maltase breaks down Maltose into glucose in primarily the small intestine but also the Salivary glands(mouth) and pancreas.
Pancreas + What does it produce
An enzyme producing gland located bellow the stomach and above the intestine: 1. Protease (trypsin) 2.amylase 3. Lipase It then releases these into the small intestine (so like alkaline)
What is the test for glucose?
Benedict's reagent (solution) 1. Add this to the sample and heat it. 2. The bendicts will turn from blue to brick red 3. THe higher the concentration of Glucose the futher the colour change goes (can only go to like green or yellow)
What other thing is involved in the process of breakig down fats that is NOT an enzyme
Bile
What is a Carbohydrase
Carbohydrase is an enzyme that catalyzes the breakdown of carbohydrates into simple sugars e.g Amyalse
Chemical formula of a single glucose molecule
C₆H₁₂O₆
What are enzymes + definition of what it is
Enzymes act as biological catalysts → a substance which INCREASES the speed of reaction, without being CHANGED or USED UP in the reaction (can be used again) in a LIVING ORGANISM
What are enzymes made of
Enzymes are all proteins and all proteins are made up of chains of amino acids. These are folded Into unique shapes, which enzymes need to do their jobs.
What is the use of enzymes + what are the reactions called?
Enzymes speed up the useful chemical reactions in the body → metabolic reactions
What is a protease
Enzymes that break down proteins into amino acids e.g pepsin and trypsin
What are lipids made off
Fatty acid and glycerol. They contain carbon hydrogen and oxygeb atoms
You need to be able to label a diagram of a Villi
Go and practice now!
Processes of the stomach
In the stomach the food is 'massaged' with gastric juices to break down complex proteins (24 hours from food to feaces)
What is the test for starch?
Iodine solution 1. Just add this to the sample 2. If starch is present the sample will change from browny- orange to a dark, blue black colour
Why doesnt your digestive track die when acid hits it?
It does but it has a very large hayflick limit so it always regenerates
What is the function of the small intestine
It futures digestion and absorbs nutrients.
Structure of the villi
Label - you have to draw 1. Inner lymphatic vessel with a lacteals head 2. Left side red blood vessel artery 3. Right side blue vein 4. There is a thin 'skin' epithelium - outer layer once cell thick (thin for diffusion and gas exchange) it permeable for exchange of soluble molecules
Adaptions of the small intestine
Large SA; -) Inner surfaces is folded -)Covered with little villi (hair like fingers) - This greatly increase the surface area in contact with the digested food' Thin wall: -) extremely thin wall to allow for easy exchange of materials Good blood supply: -) Each villus is supplied with blood vessels to receive the absorbed food Very long: -)Gives time for all the food to be digested
What are proteins made up of
Long chains of amino acids. They contain carbon, nitogen hydrogen and oxygen atoms
Look at hydrogen peroxide experiment
Look at hydrogen peroxide experiment
What breaks down MALTOSE into glucose
MALTASE
What is lots of glucose together called
Maltose
What is the function of the oesophagus in digestion
No absorption of nutrients takes place in the oesophagus. It is primarily used to transport food to the stomach for further digestion - Peristalsis is the process!
What enzyme is produced in the stomach
Pepsin - a protease - this is why breaking down of protiens happen din the stomach. It works best at PH 2 so it's well suited to the acidic condutions
What is the function of saliva in digestion
Salivary glands secrete saliva, releasing an enzyme (amylase) that changes some starches into simple sugars (MALTOSE and dextrin that can be further broken down in the small intestine) and softens the food for swallowing.
What order do the intestines go in?
Small then large
What causes heart burn
So much food is in the stomach that some acid pushes back up (burn in oesophagus)
Why do we need enzymes
Starch, proteins and fats are also insoluble + big (can't pass through the walls of the digestive system) → enzymes break them down to be soluble and small enough to be digested
Rectum
The final part of the large intestine, where faeces are STORED before they are excreted from the body.
What is the gut
The gut (gastrointestinal tract) is the long tube that starts at the mouth and ends at the anus. This can also be calld the Alimentary canal
Anus
The large opening at the end of the digestive system from which faecesexits the body
Oesophagus
The long 'tube' between the mouth and the stomach. It uses rhythmic muscle movements (called Peristalsis) to push food from the throat to the stomach
Small intestine + What does it produces
The long. thing winding tube that food goes through after it leaves the stomach: 1. Protease 2. Amylase 3. Lipase It releases these to complete digestion
What is absobrtion:
The movment of small soluble food molecules through the wall of the small intestine and into vessels that can transport them wuthin the body
Where is trypsin produced
The pancreas (goes to the small intestine)...?
Define absorbition
The process of moving molecules through the walls of the tintetsines into the blood. Digested food molecules are absorbed in the small intetsine - water is mainly absobed in the large intestine
Where is pepsin produced
The stomach (goes to the small intestine)...?
What structure do carbohydrates, proteins and fats all have
They are many polymers (many building blocks together) need to be broken down!
What structure does glucose, amino acid, glycerol and fatty acids have in common
They are monomers (polymers are made up of these) they have been broken down
What are Villus
They are tiny hair like projectionsin the small intestines that are used to increase surface area to ansorb more small soluble food molecules. They have a very good blood suppl to assist in quick abbsobtion (into the blood stream)
What is the function of teeth in digestion
They break up food increasing surface area so the enzymes can cover more of it speeding up the rate of digestion. They also break up food so that it is small enough to swallow.
What is a biological molecules
Things like carbohydrates, lipids and protiens. They're generally long and complex molecules made up from smaller basic units.
Pepsin
Turns proteins into polypetides - Polypeptides are chains of amino acids. Proteins are made up of one or more polypeptide molecules.
Use a bigger potato cube
Use a bigger potato cube!!!!
Define Egestion
When all the undigested parts of anything that has been ingested are formed into faces and exit the body via the anus
Define assimilation
When digested molecules have been absorbed, theyre moved into body cells. The digested molecules then become part of the cells - this process is known as asismilation. e.g amino acid (from digestion protines) are assimilated and used by cells to make callular protiens
When describing observations what to always remember
Write the what value that trend started from/went up to (e.g up to 35°c)
Order of bendicts colour
blue→green→yellow→orange→brick red
Practice labelling the digestive system (important)
http://www.bbc.co.uk/schools/gcsebitesize/science/add_edexcel/common_systems/digestionrev1.shtml. Its on the test 100
What is absobed into the lacteal + what is the lacteal
products of fat digestion (fatty acids and glycerol) the lymphatic vessels of the small intestine that absorb digested fats.
What is the pylorus
the opening from the stomach into the duodenum (small intestine).
