Eating disorders

Anorexiaà

-A lack or loss of appetite of food(caused by medical condition)

-An emotional disorder characterized by an obsessive desire to lose weight by refusing to eat

Bulimiaà

-Insatiable overeating as a medical condition, in particular

-An emotional disorder in which bouts of extreme overeating are followed by depression and self-induced vomiting, purging, or fasting

Binge eatingà

-A pattern of disordered eating which consists of episodes of uncontrolled eating. During binges, a person rapidly consumes an excessive amount of food.

Partial syndromeà

-You limit your intake of food and are preoccupied with your weight, you swing between frenzied eating and vomiting, and have other eating disorder symptoms, but still do not met the full diagnostic criteria for full-blown eating disorders.

Obese individuals with eating disordersà

-You eat more than you need and your weight to become too high for good health. Overweight can have other causes than eating disorders and can be caused by an eating disorder if there are psychological reasons for eating more than the body needs, such as when negative emotions(anger, boredom, disappointment etc.) cause an abnormal craving for food.

Functions of body parts in the digestive system

Mouthà

The mouth is the beginning of the digestive tract; and in fact, digestion starts at the mouth when taking your first bite of food. Chewing food breaks it down into pieces that are more easily digested, while saliva mixes with food to begin the process of breaking it down into a form your body can absorb and use.

Esophagusà

Located near your throat near your trachea(windpipe), the esophagus receives food from your mouth when you swallow, by means of a series of a muscular contractions called peristalsis, the esophagus delivers food to your stomach.

Stomachà

The stomach is a hollow organ that holds food while it is being mixed with enzymes that continue the process of breaking down the food into a usable form. Cells in the lining of the stomach secrete a string acid and powerful enzymes that are responsible for the breakdown process. When the contents of the stomach are successfully processed, they are released into the small intestine.

Small intestineà

-Made up of three segments(the duodenum, jejunum and ileum).The small intestine is a 22 foot long muscular tube that breaks down food using enzymes released by the pancreas and bile from the liver. Peristalsis is also at work at this organ, moving food through and mixing it with digestive secretions from the pancreas and the liver. The duodenum is largely responsible for the continuous breaking-down process, with the jejunum and ileum mainly responsible for the absorption of food into the bloodstream.

Contents of the small intestine start out semi-solid, and end in a liquid form after passing through the organ. Water, bile, enzymes, and mucous contribute to the change in consistency. Once the nutrients have been absorbed and the leftover-food residue liquid has passed through the small intestine, it then moves on to the large intestine, or colon. Pancreasà The pancreas secretes digestive enzymes into the duodenum, the first segment of the small intestine. These enzymes break down protein, fats, and carbohydrates. The pancreas also makes insulin, secreting it directly into the bloodstream. Insulin is the chief hormone for metabolizing sugar. Liverà The liver has multiple functions, but its main function within the digestive system is to process the nutrients absorbed from the small intestine. Bile from the liver secreted into the small intestine also plays an important role in digesting fat. In addition, the liver is the body’s chemical "factory." It takes the raw materials absorbed by the intestine and makes all the various chemicals the body needs to function. The liver also detoxifies potentially harmful chemicals. It breaks down and secretes many drugs. Gallbladderà The gallbladder stores and concentrates bile, and then releases it into the duodenum to help absorb and digest fats. Colon (large intestine)à The colon is a 6-foot long muscular tube that connects the small intestine to the rectum. The large intestine is made up of the cecum, the ascending (right) colon, the transverse (across) colon, the descending (left) colon, and the sigmoid colon, which connects to the rectum. The appendix is a small tube attached to the cecum. The large intestine is a highly specialized organ that is responsible for processing waste so that emptying the bowels is easy and convenient. Stool, or waste left over from the digestive process, is passed through the colon by means of peristalsis, first in a liquid state and ultimately in a solid form. As stool passes through the colon, water is removed. Stool is stored in the sigmoid (S-shaped) colon until a "mass movement" empties it into the rectum once or twice a day. It normally takes about 36 hours for stool to get through the colon. The stool itself is mostly food debris and bacteria. These bacteria perform several useful functions, such as synthesizing various vitamins, processing waste products and food particles, and protecting against harmful bacteria. When the descending colon becomes full of stool, or feces, it empties its contents into the rectum to begin the process of elimination. Rectumà The rectum (Latin for "straight") is an 8-inch chamber that connects the colon to the anus. It is the rectum's job to receive stool from the colon, to let the person know that there is stool to be evacuated, and to hold the stool until evacuation happens. When anything (gas or stool) comes into the rectum, sensors send a message to the brain. The brain then decides if the rectal contents can be released or not. If they can, the sphincters relax and the rectum contracts, disposing its contents. If the contents cannot be disposed, the sphincter contracts and the rectum accommodates so that the sensation temporarily goes away. Anusà The anus is the last part of the digestive tract. It is a 2-inch long canal consisting of the pelvic floor muscles and the two anal sphincters (internal and external). The lining of the upper anus is specialized to detect rectal contents. It lets you know whether the contents are liquid, gas, or solid. The anus is surrounded by sphincter muscles that are important in allowing control of stool. The pelvic floor muscle creates an angle between the rectum and the anus that stops stool from coming out when it is not supposed to. The internal sphincter is always tight, except when stool enters the rectum. It keeps us continent when we are asleep or otherwise unaware of the presence of stool. When we get an urge to go to the bathroom, we rely on our external sphincter to hold the stool until reaching a toilet, where it then relaxes to release the contents.

What is concentration gradient?

Concentration Gradient

-->change in concentration of a component across distance

Some examples of diffusion on living organisms

Difusion in Living Organisms
-Gaseous exchange during respiration and photosynthesis
-Excretion of waste products
-Absorption of digested food

What are the factors that determine the rate of diffusion?

The factors are

-Temperature

-Size of particles

-Whether the solution has ben mixed
-Thickness of barrier
-Concentration gradient
-Surface area

Do molecules even stop moving?

Diffusion stops when equal concentrations of a substance in two regions is reached

When will diffusion stop?

Diffusion will stop when the concentration of molecules is the same everywhere-evenly spread (Equilibrium)

What is diffusion?

Diffusion describes the spread of molecules through random motion from places of higher concentration to places of lower concentration.

Table of procedures

Biology: Processes of life-How big can a cell get? (29/3/2012)

Table of procedures:

Steps	Procedures
1	Fold the paper towel into 2
2	Cut into 3 strips of about 30x20mm
3	Briefly soak the strips into cabbage juice
4	Remove immediately once the paper turns light purple
5	Spread them open and leave aside to dry on the white tile
6	Cut the agar block to the following specifications: a. 3 pieces of 5x5x5mm b. 1 piece of 5x5x20mm c. 1 piece of 10x10x10mm
7	Label your petri dish accordingly based on the solutions that are assigned to you in step 2
8	Immerse one piece of agar of size 5x5x5mm, 5x5x20mm and 10x10x10mm into the lemon juice solution
9	Record the time it takes to change colour completely
10	Immerse the other two pieces of 5x5x5mm agar into the 2 remaining liquids.
11	Observe the colour change and record in Table 2
12	Introduce a few drops of each of the 3 solutions onto a different strip of the cabbage juice soaked 2-ply paper towel
13	Observe the colour change and record the results in Table 2
14	Transfer 2 square centimeter of each solution into separate test tubes.
15	Label the test tubes accordingly
16	Add an equal amount of cabbage juice into ach test tube
17	Record the colour change in Table 2