Ensure you explain the structure and function of the oesophagus and stomach.
red - means inaccurate
blue = corrections to be made


The Oesohagus To The Stomach


The journey from the oesophagus from the oesophagus to the stomach involves several organs and processes such as:

The Gastric Pit

Mechanical and Chemical Digestion

Sphincter Muscle

Peristalsis

The Oesophagus

The Stomach

Group One which which consists of Bryce Orr, Jerome Ottley, Brandon Paryag, Dominic Smart, Nicholas O'Brien, Kyle Ng and Jordan O'Brien have put together this presentation for educational purposes.

The Oesophagus

The oesophagus is an organ which is found in animals with back bones (vertebrates) which consists of a muscular tube through which food passes from the pharynx to the stomach. The oesophagus is also known as the gullet. The function of:

the oesophagus is to carry foods, liquids and saliva to the stomach.

The stomach then acts as a container to start digestion and pump food and liquids into the intestines in a controlled process.

http://www.youtube.com/watch?v=rJS-Kh5wCQU

Sphincters prevent materials from moving backward or allow materials to move from one segment of the digestive system into the next a little at a time.

The cardiac (esophageal) sphincter keeps materials from splashing back up into the esophagus(as it occur acid reflux); the pyloric sphincter prevents the entire stomach contents from entering the duodenum all at one time:

(allows more time for protein digestion)

(and it is easier for bile secretions to neutralise small portiond of acidic chyme) .


Mechanical digestion and Chemical digestion

MECHANICAL DIGESTION

An example of Mechanical digestion is the process by which the teeth in the mouth crush up food into smaller pieces but it still remains the same substance it was before it was eaten. In mechanical digestion the main parts involved are the teeth and stomach also bile.This is important as it is easier for the stomach and small intestines that follow to digest this food using chemical digestion.

The food is digested faster as there is a larger surface area to volume ratio .


CHEMICAL DIGESTION

Chemical digestion is the process by which the saliva in the mouth makes food smaller but also changes the food into another substance that the body can use. In chemical digestion the main parts involved with this process are from the mouth all the way up to the ileum. Chemical digestion is important as it - (is necessary as the body would not be able to function the body would not) - provides and makes available via absorption the vital nutrients needed for survival.


Here is a diagram to shows chemical digestion. and mechanical digestion in the body:

enzymes_digestion.jpg

Peristalsis In The Oesophagus


Peristalsis is a series of organized muscle contractions that occur throughout the digestive tract. This mechanical action has to do with sets of muscles that work together to move both liquid and solid food along the digestive tract. Gravitational pull is reduced when food enters the oesophagus because of peristalsis. Peristalsis helps a person to swallow lying down or even standing on their head.

Peristalsis has another important task besides assisting in the movement of food through the body. It also helps to knead, agitate and pound the solid residue that is left after the teeth or for those without teeth, the gums, have done their best when grinding and pounding it to small pieces.

The process looks similar to an earthworm propelling itself through the ground. The muscle contracts creating a narrowing that slowly moves down the length oesophagus. It take approximately 8-9 seconds for the food to travel from the mouth, through the oesophagus and then to the stomach.

If the bolus of food does not reach the stomach in the first set of waves, it activates a second set of waves with the high possibility of reaching to the stomach, also delaying the time to get to the stomach. This may occur with "under-chewing" food, eating foods that are difficult to chew or sometimes, gobbling your at a very short period of time as the food may clump close together and may be difficult to go down.

Here are images demonstrating peristalsis in the oesophagus:

download (1).jpg download (2).jpg

The Gastric Pit


Gastric pits are the numerous depressions in the mucous membrane lining the stomach into which the gastric glands release gastric juices.

Image513.gif



Functions Of The Gastric Juices

⦁ The top of the gastric pits are lined with mucus cells which provide a protective layer for the acidic stomach.

⦁ The gastric glands are enteroendocrine because they secrete a hormone known as gastrin into the blood to raise the levels of digestive action in the stomach.

⦁ The parietal cells which secrete HCl are lightly stained and are in the middle of the mucosal layer.

⦁ The chief cells which secrete pepsinogen are stained dark and are deep in the mucosal layer.

fair explantion throughout
  1. format was fair excet for the separation of info about the oesophagus
  2. error in title of diagram showing only chemical digestion betweenenzymes and major nutrients
  3. the flow chart did not suggest names of enzymes associated with protein digestion especially related to the stomach
  4. reasons or importance of chemical digestion needed clarity
  5. the actual function of enzyme pepsin and HCl was not discussed



good info that describes the oesophagus stomach but
  1. no clarity and link made with the terms chemical and mechanical digestion
  2. no mention of the epiglotis and its importance to direct food down the oesophagus
  3. error or lack of clarity about the exact function of HCl it does not 'digest food'