Digestion of Fat

The presence of fat in the small intestine produces hormones which stimulate the release of lipase from the pancreas and bile from the gall bladder. The lipase breaks down the fat into monoglycerides and fatty acids. The bile emulsifies the fatty acids so they may be easily absorbed.

Within the villi, the chylomicron enters a lymphatic capillary called a lacteal, which merges into larger lymphatic vessels. It is transported via the lymphatic system and the thoracic duct up to a location near the heart . The thoracic duct empties the chylomicrons into the bloodstream via the left subclavian vein. At this point the chylomicrons can transport the triglycerides to where they are needed.

The 4 agents that assists digestion

These are the four hormones that aid and regulate the digestive system:

Gastrin - is in the stomach and stimulates the Gastric Glands to secrete Pepsinogen and hydrochloric acid. Secretion of gastrin is stimulated by food arriving in stomach. The secretion is inhibited by low pH.

Secretin- is in the duodenum and signals the secretion of sodium bicarbonate in the pancreas and it stimulates the bile secretion in the liver. This hormone responds to the acidity of the chyme.

Cholecystokinin - is in the duodenum and stimulates the release of digestive enzymes in the pancreas and stimulates the emptying of bile in the gall bladder. This hormone is secreted in response to fat in chyme.

Gastric inhibitor peptide- is in the duodenum and decreases the stomach churning in turn slowing the emptying in the stomach. Another function is to induce insulin secretion.

The Large Intestines

After the food has been passed through the small intestine, the food enters the large intestines. The large intestine is roughly 1.5 meters long, with three parts: the cecum at the junction with the small intestines, the colon, and the rectum. The colon itself has four parts: the ascending colon, the transverse colon, the descending colon, and the sigmoid colon. The large intestine absorbs water from the bolus and stores feces until it can be egested. Food products that cannot go through the villi, such as cellulose, are mixed with other waste products from the body and become hard and concentrated feces. The feces is stored in the rectum for a certain period and then the stored feces is egested due to the contraction and relaxation through the anus. The exit of this waste material is regulated by the anal sphincter.

The small intestines.

After being processed in the stomach, food is passed to the small intestines via the Pyloric sphincter. The majority of digestion and absorption that occurs here as chyme enters the duodenu. Here it is further mixed with three different liquids:

1. Bile, which emulsifies fats to allow absorption, neutralises the chyme, and is used to excrete waste products such as bilin and bile acids. It is not an enzyme, however. The bile juice is stored in a small organ called the gall bladder.
2. Pancreatic Juices made by the pancreas.
3. Intestinal enzymes of the alkaline mucosal membranes. The enzymes include: maltase, lactase and sucrase, to process sugars; trypsin and chymotrypsin are also added in the small intestine.

The Stomach, What happens in there?

In the stomach, food is further broken apart, and thoroughly mixed with a gastric acid and digestive enzymes that break down proteins. The acid itself does not break down food molecules, rather, the acid provides an optimum pH for the reaction of the enzyme pepsin. The parietial cells of the stomach also secrete a glycoprotein called intrinsic factor which enables the absorption of vitamin B-12. Other small molecules such as alcohol are absorbed in the stomach as well by passing through the membrane of the stomach and entering the circulatory system directly.

The Throat, what does it do?

The Esophagus, also known as throat, a narrow, muscular tube about 30 centimeters (12 inches) long, starts at the pharynx, passes through the larynx and diaphragm, and ends at the cardiac orifice of the stomach. The wall of the Esophagus is made up of two layers of smooth muscles, which form a continuous layer from the Esophagus to the rectum and contract slowly, over long periods of time. The inner layer of muscles is arranged circularly in a series of descending rings, while the outer layer is arranged longitudinally. At the top of the Esophagus, is a flap of tissue called the epiglottis that closes during swallowing to prevent food from entering the trachea (windpipe). The chewed food is pushed down the Esophagus to the stomach through peristaltic contraction of these muscles. It takes only seconds for food to pass through the Esophagus, and little digestion actually takes place.

The Digestion Phases

The Cephalic Phase- This phase occurs before food enters the stomach and involves preparation of the body for eating and digestion. Sight and thought stimulate the cerebral cortex. Taste and smell stimulus is sent to the hypothalamus and medulla oblongata. After this it is routed through the vagus nerve and release of acetylcholine. Gastric secretion at this phase rises to 40% of maximum rate. Acidity in the stomach is not buffered by food at this point.

Gastric phase - This phase takes 3 to 4 hours. It is stimulated by distention of the stomach, presence of food in stomach and increase in pH. Distention activates long and myentric reflexes. As protein enters the stomach, it binds to hydrogen ions, which raises the pH of the stomach to around pH 6. Inhibition of gastrin and HCl secretion is lifted.

What happens when food enters our mouth?

In humans, digestion begins in the oral cavity where food is chewed. Saliva is secreted in large amounts by three pairs of exocrine salivary glands in the oral cavity, and is mixed with the chewed food by the tongue. There are two types of saliva. One is a thin, watery secretion, and its purpose is to wet the food. The other is a thick, mucous secretion, and it acts as a lubricant and causes food particles to stick together and form a bolus. The saliva serves to clean the oral cavity and moisten the food, and contains digestive enzymes such as salivary amylase, which aids in the chemical breakdown of polysaccharides such as starch into disaccharides such as maltose. It also contains mucin, a glycoprotein which helps soften the food into a bolus.

The Digestive System

Digestion is the breaking down of food in the body, into a form that can be absorbed and used or excreted. It is also the process by which the body breaks down food into smaller components that can be absorbed by the blood stream. In mammals, preparation for digestion begins with the cephalic phase in which saliva is produced in the mouth and digestive enzymes are produced in the stomach. Mechanical and chemical digestion begin in the mouth where food is chewed, and mixed with saliva to break down starches. The stomach continues to break food down mechanically and chemically through the churning of the stomach and mixing with enzymes. Absorption occurs in the stomach and gastrointestinal tract, and the process finishes with excretion.

Rainforests, why should we protect them?

Rainforests are home to two-thirds of all the living animal and living animal and plant species of the Earth. It has been estimated that many hundreds of millions of species of plants, insects and microorganisms are still undiscovered. Tropical rainforests have been called the "jewels of the Earth," and the "world's largest pharmacy," because of the large number of natural medicines discovered there.

A natural rainforest emits and absorbs vast quantities of carbon dioxide. On a global scale, long-term fluxes are approximately in balance, so that an undisturbed rainforest would have a small net impact on atmospheric carbon dioxide levels, though they may have other climatic effects . No rainforest today can be considered to be undisturbed. Human induced deforestation plays a significant role in causing rainforests to release carbon dioxide, as do natural processes such as drought that result in tree death.Some climate models run with interactive vegetation predict a large loss of Amazonian rainforest around 2050 due to drought, leading to forest dieback and the subsequent feedback of releasing more carbon dioxide.

Tropical rainforests provide timber as well as animal products such as meat and hides. Rainforests also have value as tourism destinations and for the ecosystem services provided. Many foods originally came from tropical forests, and are still mostly grown on plantations in regions that were formerly primary forest. Tropical rainforests are also the source of medicinal drug components.

About half of the mature tropical rainforests, between 750 to 800 million hectares of the original 1.5 to 1.6 billion hectares that once graced the planet have already fallen. The devastation is already acute in South East Asia, the second of the world's great biodiversity hot spots. Most of what remains is in the Amazon, where the Amazon Rainforest covered more than 600 million hectares, an area nearly two thirds the size of the United States. The forests are being destroyed at an ever-quickening pace. Unless significant measures are taken on a world-wide basis to preserve them, by 2030 there will only be 10% remaining with another 10% in a degraded condition. 80% will have been lost and with them the natural diversity they contain will become extinct.

The Rafflesia, why does it smell?

Rafflesia is a genus of parasitic flowering plants, all found in the SouthEastern part of Asia, on the Malay Peninsula, Borneo, Sumatra and Kalimantan, West Malaysia and the Philippines. The plant has no stems, leaves or true roots. The only part of the plant that can be seen outside the host vine is the 5-petaled flower. The flower look and smell like rotting meat, hence the local names which translates to "corpse flower" or "meat flower".
The vile smell that the flower gives off attracts insects such as Carrion flies, which transport pollen from male to female flowers.
. However, tree shrews and other forest mammals apparently eat the fruits and disperse the seeds. Rafflesia is an official state flower of Sabah in Malaysia, as well as for the Surat Thani Province of Thailand.

The Venus FlyTrap

The Venus Flytrap is a small herb, forming a rosette of four to seven leaves, which arise from a short subterranean stem that is actually a bulb-like rhizome. Each leaf reaches a maximum size of about three to ten centimeters, depending on the time of year;longer leaves with robust traps are usually formed after flowering. Flytraps that have more than 7 leaves are colonies formed by rosettes that have divided beneath the ground.
The Venus Flytrap is one of a very small group of plants that are capable of rapid movement.
The mechanism by which the trap snaps shut involves a complex interaction between elasticity, turgor and growth. In the open, untripped state, the lobes are convex, but in the closed state, the lobes are concave. It is the rapid flipping of this bistable state that closes the trap.
The Venus Flytrap is found in nitrogen-poor environments, such as bogs and wet savannahs, and survives in wet sandy and peaty soils. Although it has been successfully transplanted and grown in many locales around the world, it is found natively only in North and South Carolina in the United States

How do plants like Cactus survive in the Desert

Cacti have never lost their leaves completely; they have only reduced the size so that they reduce the surface area through which water can be lost by transpiration. In some species the leaves are still remarkably large and ordinary while in other species they have become microscopic but they still contain the stomata, xylem and pholem Certain cactus species have also developed ephermeral leaves which are leaves that last for a short period of time when the stem is still in its early stages of development. A good example of a species that has ephemeral leaves is the prickly pear.
The bodies of many cacti have become thickened during the course of evolution, and form water-retentive tissue and in many cases assume the optimal shape of the sphere.

What are Plants doing to adapt to Global Warming

Photosynthesis in plants relies upon the efficient collection of sunlight. This process can work even at low levels of sunlight, when plants are in the shade or under cloud cover for example. However, when the sun is very bright or when it is cold or very dry, the level of light energy absorbed by leaves can be greatly in excess of that which can be used in photosynthesis and can destroy the plant. However, plants employ a remarkable process called photoprotection, in which a change takes place in the leaves so that the excess light energy is converted into heat, which is harmlessly dispersed.

Plants in everyday life

Plants in our everyday life:

Clothes-One of the most important natural fibres in the world comes from cotton plants.Linen is made from flax plant.Wood fibres give us cellulose,which is used to manufacture viscose.

Bread- Most bread are made from cereal grains such as wheat and rye.

Sugar- Green plants produces sugar and various plants have their sap extracted to produce sweet syrup such as maple. Most of the world's sugar comes from Sugar Cane.

Medicine - Plants have long been used for their natural healing properties.Many are used in modern medicines,examples are the leaves of foxglove,they contain a substances that is used to treat heart conditions. In correct doses,it helps the heart to beat more slowly and stronger. Large doses could be fatal.

What is Man's reaction?

Now,as the world is facing an inevitable disaster; Global Warming, Man is finally working together to prevent or at the least, delay it.. but it is too late.. Warnings were given but Man did not heed them,among them is the 2006 Tsunami in Sumatra. Since 2006, efforts by Man to stop Global Warming has at least doubled or tripled. An example would be supermarkets around the world has stopped distributing Plastic Bags, customers are required to bring their own paper bags or they would have to pay extra to get Plastic Bags.. when plastic bags are sent to the incinerators, they are burned, when they are burned, toxic chemicals are released into the atmosphere, an effect of the chemicals is the hole in the Ozone Layer.

The Ozone Layer is a protective layer in the atmosphere that reflects the Sun's harmful Ultraviolet Rays from burning the Earth,the chemicals destroys this Ozone Layer and caused a hole in it, though the hole is starting to seal up, Man has already done too much to revert the effect..

What is Man doing to the plants?

As time passes, Man starts to forget what Plants were for, Man starts to have greed, Man starts to destroy Plants to manufacture what they desire, in ancient times, plants were abound, so Man thought that there were enough for all, thus, Man started to chop down trees for firewood and lumber.
Compared to modern times, Man is still doing the same, though less in numbers, hectares of forests are being cleared daily despite threats by their Government. The Rainforests once covered 1.5 to 1.6 billion hectares of this planet, now left with about half,due to excessive deforestation by Man

Importance of plants

Plants produces food

Plants are the only organisms that can convert light energy from the sun into food. And plants produce ALL of the food that animals, including people, eat. Even meat. The animals that give us meat, such as chickens and cows, eat grass, oats, corn, or some other plants.

Plants produces oxygen

One of the materials that plants produce as they make food is oxygen gas. This oxygen gas, which is an important part of the air, is the gas that plants and animals must have in order to stay alive. All of the oxygen available for living organisms comes from plants.

Plants preserves soil
In the forest and the prairie, the roots of plants help hold the soil together. This reduces erosion and helps conserve the soil. When plants die, their decomposed remains are added to the soil. This helps to make the soil rich with nutrients.

Plants produces resources for Man
Many plants are important sources of products that people use, including food, fibers and medicines. Plants also help provide some of our energy needs. In some parts of the world, wood is the primary fuel used by people to cook their meals and heat their homes. Many of the other types of fuel we use today, such as coal, natural gas, and gasoline, were made from plants that lived millions of years ago.

Welcome to my BioJournal!

The topic i will be posting on is: Plants and our Ecology and Digestive System

Why plants?
Plants are the silent guardians of this planet,without them,this planet would have long ago been destroyed..
My Bio-Journal will be touching on what the plants do to sustain this planet.
And man should respect them as they are a factor to ensure the survival of this planet.

Why the Digestive System?
Our Digestive System is always overlooked by people,it is actually more important than what most people think.