Digestion - Alimentary Canal

Hey Sup People! How are you doing this afternoon? Hope you are doing gggggggggrrrrrrrreeeeeeeaaaatttt! (GREAT)

Okay, enough of the introduction :) So today's topic is also about Digestion, but we're moving on to another topic, the Alimentary Canal. I know you must be thinking: "Hey we've learnt this before! Why are we learning this again?" Yes I know that question very well, but here, we're going in dept about all the organs, and stuffs.

So let me list out the enzymes the substrates, and the end product.

Carbohydrate

Starch ( Salivary Amylase) Maltose
Maltose (Maltase)             Glucose

Protein

Protein          (Pepsin)               Polypeptides
Polypeptides (Erepsin/Trypsin) Amino Acids

Fats

Fats      (Bile)     Emulsified Fats
E. Fats (Lipase) 3 Fatty acids + 1 Glycerol

Okay, so now you've seen all the reactions, let's get down to all the organs in the alimentary canal, and their functions. Please get your paper and pens/pencils ready, for the next few paragraphs would be a rollercoaster ride. (0_0 That's exaggerating)

Mouth

• Contains teeth that chews food molecules into smaller food substances so that it would have a larger surface area for more enzymes to act on it
• In here, starch is digested by the salivary amylase to form maltose
• The saliva secreted by the salivary glands produces the enzyme, and it also softens, and mixes the food
• The tongue rolls the partially digested food into a bolus before it is being swallowed down.

Oesophagus

• It is also known as the gullet, but at this level, it should be called the oesophagus
• No digestion takes place here
• There are 2 muscle that aids in Peristalsis (The next point) - the longitudinal muslce, and the circular muscle
• Peristalsis - The rhythemic wave-like contraction of muscles that propels and mixes the contents of the alimentary canal forward

Stomach

• The stomach is an elastic, muscular bag with thick elastic walls.
• It secretes a mixture of gastric juice - hydrochloric juice, pepsin, and rennin
• The stomach contracts and relaxes so that the foods are well mixed with the gastric juices
• In here, protein is being digested in polypeptides by the enzyme pepsin
• The end product is a semi-liquid product called chyme, that is being released into the duodenum, the first part fo the small intestine.
• The interesting thing about a stomach is that it is the only organ which has a pH value of 2 (refer to the previous post about pH values)

Liver, Gall Bladder, Pancreas 

Digestion - Enzymes

Hey's People, I'm back after a break, if you can see the timing. But anyways, here's the 2^nd part of the mighty digestion! (Y) The.....*Drum Roll Please*.....Enzymes! (Y)

Anyway, Enzymes are really simple to understand, but you have to remember a lot of things, but if you write it all out on 1 piece of foolscap paper, I guess you'll remember it better, by a lot, so anyways, good luck!

So Here's the Definition of enzymes.

Enzymes are Proteins. (Please remember that) They are biological catalysts that help speed up the rate of chemical reactions without themselves being broken down at the end of the reaction. (How cool is that?)

Enzymes - Conditions

Yes, there are conditions, like the T&Cs that we humans have. There are 2 main conditions for the best enzymes reactions, and I think you'll find it easy to remember. :)

1. Optimum Temperature

It basically means the temperature at which the enzymes works best in, which is room temperature of about 37 degrees or so (plus minus) and some questions usually states 40 degrees, which is also considered. At this temperature - room temperature - the enzymes reactions with the substrate is at it's peak, but after that temperature, the enzymes would slowly denature, meaning that the reactions would become slowly, and the enzymes would slowly die.

However do please take note that in scientific terms, the enzymes do not die but denature.

2. pH Values

Sorry to say that we have not learnt Chemistry as we would be learning it the next term, but I guess it is just the acidity and the alkaline, and in this case, it is the pH values of the enzymes.

salivary amlase works best in pH7
protease works best in pH2
lipase works best in pH 7~8

Digestion - nutrients

Heys People! I know I'm posting at such a late date, but at least I posted....right? Anyways, here is what I think is the summary of digestion. I've summarised the points I think is required for the exam, as well as adding in several other informations I think it would be fun to know, maybe. But anyways, here it is!

Digestion is basically just the breaking down of large, insoluble, indiffusible food substances into smaller, soluble, and diffusible food substances.

Easy to remember...right? Yeahs.

So anyways, there are 3 types of nutrients in total - carbohydrates, proteins, and fats.

Carbohydrates:

It provides energy for the body cells.

There are 3 types of carbohydrates, mainly the diasaccharides, monosaccharides, and the polysaccharides. I would not go into detail for that as you people have to study!!!

So anyways, there are 2 type of tests for carbohydrates, the Benedicts Test and the Iodine Test.

It is made up of Carbon, Hydrogen, and Oxygen (CHO)

Benedicts Test:

It tests for reducing sugar, and if reducing sugar is present, the solution would become reddish (is there even such a word?) -orange precipitate. If not, it would just remain as blue.

Iodine Test

It tests for, as you all should know, for starch. So, if starch is present, the solution would turn blue-black, or if starch is not present, then the solution would remain brown/yellow, depending on the colour of the iodine at first. But I guess it would be better if you choose brown instead, to you know, just to play safe XD

Protein:

It is the main substance used for the growth of new cells, and the repair of damaged cells. It also provides energy when the body lacks fats, or carbohydrates.

It is made up of Carbon, Hydrogen, Oxygen, and Nitrogen.

Protein can never never be stored as it is TOXIC!!!! Thus, it is removed by the body via egestion, as urea in urine.

Biuret's Test

The biuret test is used to test for the presence of protein. If protein is present, the solution would change to violet (yeah!!! 0_0). If not, it wouls remain as blue.