Saturday, 28 April 2012

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.

Friday, 6 April 2012

What is concentration gradient?

Concentration Gradient

-->change in concentration of a component across distance

Friday, 30 March 2012

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)