DIGESTION IN HUMAN & ROLE OF LIVER

DIGESTION IN HUMAN:
                            Our cells require oxygen, water, salts, amino acids, sugar, fatty acids, and vitamins. These can cross cell members to enter cells. Amino acids, simple sugars and fatty acids are rare our environment. Such substances are usually parts of larger molecules like proteins, polysaccharides and lipids, which cannot cross the membranes. There is a need of converting such large and non-diffusible molecules into smaller and diffusible molecules. This is achieved through the process of digestion.

After digestion the diffusible molecules from the digestion system reach body cells through blood. Here they are assimilated. At the same time, the indigestible part of food is assimilated. At the same time, the indigestible part of food is eliminated out of body through the process of defecation. In simple ways , the nutrition in humans comprises of following phases.

1.       Ingestion: The process of taking in food.

2.       Digestion: The process of breaking up complex substances into simpler substances.

3.       Absorption: Diffusion of digested food into blood and lymph.

4.       Assimilation: Conversion or incorporation of absorbed simple food into the complex substances constituting the body.

5.       Defecation: Elimination of undigested food from the body.

ROLE OF LIVER:

            Liver is the largest gland of our body. It is multi-lobed and dark reddish in appearance. It lies beneath the diaphragm on the right side of abdomen. In adult human, its weights about 1.5kg and is the size of football. A pear-shaped greenish yellow i.e gallbladder lies along the right lobe of liver on ventral side.

Liver secretes bile, which is stored in gallbladder. When gallbladder contracts,  bile is released into duodenum through common bile duct. Bile has no enzymes but contains bile salts for the emulsification of lipids. It helps the lipid-digesting enzymes to attack on lipids. Liver carries out a number functions some of which are summarized here;

1.       Removes amino groups from amino acids

2.       Converts glucose into glycogen and break glycogen into glucose.

3.       Converts ammonia to less toxic from; urea

4.       Destroys the old red blood cells.

5.       Manufactures blood clotting proteins called fibrinogen.

6.      Converts carbohydrates and protein into lipids and produces cholesterol.

7.       Produce heat to maintain body temperature.

 Stores fat-soluble vitamins and mineral ions, such as iron.

PROBLEMS IN NUTRITION :

Problems related to nutrition are grouped as malnutrition. It often refers to under-nutrition resulting from inadequate consumption, poor absorption, or excessive loss of nutrients. Malnutrition also includes over-nutrition, resulting from overeating or excessive intake of specific nutrients.

Sometime, malnourished people either do not have enough calories in their food, or eat a diet that lacks protein, vitamins, or trace minerals. Malnutrition weakens the immune system, impairs physical and mental health, slows thinking, stunts growth and affects fetal development. Common Forms of malnutrition include protein-energy malnutrition, mineral deficiency disease, and over-intake of nutrients.

A-Protein Energy Nutrition:

 Protein- energy malnutrition means inadequate availability or absorption of energy and protein in body. It is the leading cause of death in children in developing countries. It may lead to diseases such as Kwashiorkor and Marasmus.

 FAMINE-THE MAJOR CAUSE OF MALNUTRITION:

                                                 Famine means lack of enough food to feed all people living in area. The most terrible famines of the twentieth century are Ethiopian famine and North Korean famine. The major causes of famine are unequal distribution of food, drought flooding or increasing population. Some people life happy life with good health and wealth but some of people are in very bad condition they have no health and wealth this is because of un equality in peoples. Some of us not want other live happy and healthy life because of this we not progress and we go down and cause some several disease.

1.       Unequal distribution of food:

The achievements in science have enable human beings to produce better food in terms of quality and quality. Today the agricultural practices produce more than enough food that can be supplied to everyone on the earth. But due to political and administrative problems food is not equally distributed to different regions of world. The result is that there is always surplus food in countries like America , Uk, and Canada etc and at same time people have nothing to eat in different countries like Ethiopia , Somalia etc .

2.       Drought :

               A drought is a period of time when there is not enough water to support agricultural and human needs. Drought is usually due to a long period of below-normal rainfall. Droughts decrease or even stop the crop yields and it results in famine.

3.       Flooding :

              Its occurs due to more than normal rainfall or due to weak water distribution system. Rivers and canals overflow their banks and destroy the soil quality of agricultural lands. It becomes impossible to grow crops immediately after flooding. In this way, flooding may be a reason for short-term famine.

4.       Increasing population:

                          In spite of global increase in food production, millions of human beings are undernourished. In the over-populated regions of world, large populations overuse natural resources to grow maximum food in order to meet the problems of food shortage.  It leads to dry and infertile lands and depletion of resources. In such situations crops can no longer be grown and famines result.

HEALTH DEPENDS ON :

                      

Water:

        Approximately 60% of adult human body is composed of water. All life-sustaining chemical reactions require an aqueous environment. Water also functions as the environment in which water-soluble foodstuff is absorbed in the intestines and waste products are eliminated in urine. Another essential role of water is to maintain body temperature through evaporation as in sweating. Severe dehydration may result in  cardiovascular problems. The estimated water requirement of an average adult is two litres per day. Important sources of daily water intake are natural water, juicy fruits, milk and vegetables.

Dietary Fibre:

Dietary fibre is part of human food that is indigestible. It is found only in plant foods and it moves undigested through stomach and small intestine and into colon. The insoluble dietary fibre travels quickly through small intestine. Its sources are wheat bran, cereals and skins of many fruits and vegetables.

The soluble dietary fibre breaks down as it passes through alimentary canal. Its sources are oats, barley, beans, and many fruits and vegetables.

Fibre prevents and relieves constipation by stimulating the contraction of intestinal muscles. Avoiding constipation reduces the risk of many other diseases. Soluble fibre helps in lowering blood cholesterol and sugar levels. Insoluble fibre speeds up the movement of carcinogens from intestine.

Balanced diet:

Humans require various types of nutrients in order to keep them healthy and fit. These nutrients should be taken appropriately in diet. A balanced diet may be defined as the one which contains all essential nutrients in correct proportion for the normal growth and development of body. A balanced diet is related to one’s age, gender and activity. Its should include different types of nutrients and should be according to energy requirements. The following chart shows some of the common foods, taken in Pakistan and percentage of carbohydrates, lipids and proteins in each of them .

             Common Foods and the Percentage of nutrients : 

                  Food                         Carbohydrates                   Lipids                    proteins 

              Bread                                               52%                                  03%                         09%

                 Rice                                        23%                          0.1%                    2.2% 

              Potato                                             19%                                 0.1%                         02%

              Apple                                   12.8%                          0.5%                    0.3%  

              Eggs                                      0.7%                           12%                    13%

              Milk                                       04%                            04%                    03%

              Butter                                     0.4%                          81%                    0.6%

              Chicken                                   0                                1%                    20%  

DEFORESTATION AND OVER-HUNTING:

Deforestation means cutting down of trees for the conversation of a forest to non-forest land .

The destruction of significant areas of forest has resulted in a degraded environment with reduced biodiversity.

Causes and effects of deforestation:

Cause of deforestation:  

                                    Sometime there is slow forest degradation and sometime sudden and catastrophic clear-cutting for urban development.

Deforestation can be result of deliberate  removal of forests for wood, agriculture or urban development.

Effect of deforestation:

                             Deforestation effects  the amount of water in soil and moisture in atmosphere.

Soil erosion:  When there are no trees to keep soil in place, there are more chances of soil erosion. Heavy rainfall washes soil into rivers.

Essential nutrients are washed out of soil.

Floods: Rivers become choked up with mud and silt, which can cause floods. The silted water gets stored in dams and it reduces their water storage capacity.

Decreasing rain: Deforestation also contributes to decreased transpiration, which lessens cloud formation. This ultimately reduces the sources of rains.

Forest support considerable biodiversity. The utilization of forest products , including timber and fuel wood, have played a key role in human societies.

Today developed countries continue to utilize timber for building houses and wood pulp for making paper. The forest products industry is a large part of the economy

In developing countries. Short-term economic gains made by conversion of forest to agriculture often leads to loss of long-term income.

Forests extract carbon dioxide and pollutanats from air , thus contributing to biosphere stability.  Forest are also valued  for their  aesthetic beauty and tourist attraction.

Over-Hunting:

Over-hunting has been a significant cause of the extinction of hundreds of species and the endangerment of many more such as whales, ibex, urial, markhor etc.

Commerical hunting both legal and illegal  is the principal of threat . Over-hunting cause loss of tigers. The tigers are less in amount because of illegal hunting of tigers. 

HISTORY OF CLASSIFICATION:

In 700s, ABU-USMAN UMER AIJAHIZ described  the characteristics of 350 species of animals in his book . He wrote a lot about the life of ants. In 1172, IBN RUSHD translated  Aristotle,s book “ de anima”

TWO-KINGDOM:

According to old system all organisms classify into two  kingdoms ,     plantae and animalia.

Plantae:

All organisms which can prepare Food from simple inorganic materials and store energy , are autotrophs and include in kinddom Plantae.

Animalia:

The Organisms that cannot synthesize their food and depend on autotrophs  , these are heterotrophs and are include in kingdom animalia .

According to this system  , bacteria , fungi , and algae were included in  kingdom plantae.

Some taxonomists  found this system is unworkable because , many unicellular organisms like Euglena have both plantae and animalia.

So these are in separate kingdom for such organisms.

THREE-KINGDOM:

In 1866, ERNST HACKEL solved the first objection and proposed a third kingdom.

But this is not clear the difference b/w prokaryotes and eukaryotes.

Some biologists disagreed about the position of fungi in plantae.

Fungi resemble plants in many ways but ar not autotrophs. They are special form of heterotrophs  that Get their food by obsorption.

FIVE-KINGDOM:

In 1937 , E-chatton   suggested the two terms “procariotique” and “Eucariotique”

Procariotique:

To describe bacteria

Eucariotique:

To describe animal and plant cells .

In 1967 , ROBERT WHITTAKER  solved the problem and introduced the five-kingdom classification system .

This  system is Based on ;

1.       The level of cellular organization i.e. Prokaryotic, unicellular eukaryotic and multicellular eukaryotic

2.       The principal modes of nutrition i.e. photosynthesis, absorption , and  ingestion

On this basis , organisms are classified into five kingdom classification of Whittaker

They  considered genetics along with cellular organization  and mode of nutrition in classification .  They classified the organisms into same five kingdoms as proposed by Wittaker.

 THE FIVE KINGDOMS :

1.   Kingdom monera:

It includes prokaryotic organisms.

Monerans are unicellular , although some types from chains, clusters , or colonies of cells. Prokaryotic cells are radically different from eukaryotic cells . Most are heterotrophic.

2.   KINGDOM PROTISTA:

It includes eukaryotic unicellular and simple multicellular organisms .

. Algae are cellular , colonial or simple muticellular . They resemble plant cells with cell walls and chlorophyll in chloroplasts.

Simple multicellular means that they do not have multicellular sex organs and do not form embryos during their life cycles.

. Protozoans resemble animals whose cells lack  chlorophyll and cell walls.

. Some protists are Fungi-like.

3.Kingdom Fungi :

It includes eukaryotic muticellular heterotrophs which are absorptive in their nutritional mode e.g Mushrooms.

They live on organic material

4.kingdom Plantae:

It includes  eukaryotic muticellular autotrophs. Plants are autotrophic in nutritional mode , making their own food by photosynthesis .

5.KINGDOM ANIMALIA:

It includes enkaryotic multicellular consumers .

 Animalia live mostly by ingesting food and digestive  it within specialized cavities . They lack cell wall  and show movements.

What is SPECIES? And HISTORY OF CLASSIFICATION?

SPECIES IS THE BASIC UNIT OF CLASSIFICATION:

DEFINATION OF SPECIES: A species is a group of organisms which can interbreed freely among them the produce fertile offspring, but are reproductively isolated from all other such groups in nature.

In definition of species we must emphasize “in nature” because two organisms related to two different but closely related species can cross-breed under artificial conditions. In such unnatural cross they produces infertile offspring. For example, a cross between a male donkey and female horse produces an infertile offspring i.e, MULE.

HISTORY OF CLASSIFICATION SYSTEM:

The earliest known system of classification of organisms comes from the Greek philosopher Aristotle. He Classified  all living organisms known at time as either in the group ‘plantae’ or in ‘amimalia’.



In 700s, Abu-Usman Umer Aljahiz described the Characteristics of 350 species of animal in the Book.He wrote about life of ants. 

What is BASIS OF CLASSIFICATION?

BASIS OF CLASSIFICATION:

Classification is based on relationship amongst organisms and such relationship is got through similarities in characteristics. These similarities suggest that all organisms are related to one another to some point in their evolutionary histories.

However, some organisms are more closely related than others. For example sparrows are more closely related to pigeons than to insects. It means that the former two have common evolutionary histories.

When biologists classify organisms into group and subgroups, the similarities are seen in external and internal structures and stages of development. Modern genetics provides another type of information to taxonomists. The similarities and different in the DNA of two studied organisms can be used for getting idea about similarities and differences in their structure s and functions.

TAXONOMIC HIERARCHY:

The groups into which organisms are classified are known as taxonomic categories or taxa.

The taxa from a ladder, called taxonomic hierarchy.

All the organisms are divided into five kingdoms. So kingdom is largest  taxon. Kingdom is further divided.

1. Phylum: A phylum is a group of related classes.

2. Class: A class is a group of related orders.

3. Order: An order is a group of related families.

4. Family: A family is a group of related genera.

5. Genus: A genus is group of related species.

6. Species: A species consist of similar organisms.

SIMPLE CLASSIFICATION OF TWO ORGANISMS:

Tax           Human           Pea

   Kingdom      Animalia         Plantae

  Phylum        Chordata         Magnoliophyta

 

  Class        Mammalia          Magnoliopsida

  Order        Primates          Fabales

  

Family        Hominidae         Fabaceae

Genus         Homo              Pisum

Species       H.sapiens         Sativum

WHAT IS BIODIVERSITY AND ITS IMPORTANCE? HOW THE WORD BIODIVERSITY DERIVED?

All most 10 million kinds of organisms inhabit the earth but less than one third of these have been studied and catalogued by biologists . Diversity  among the earth organisms is more obvious than fundamental unity of life . We see that all organisms share many biological characteristics. Five  principal groups of organisms are prokaryotes , protists , fungi, plants, and animals .  We will focus on the differences among different groups of organisms . How Organisms Classified and named and what are the concerns with the existence of biodiversity.

BIODIVERSITY:

 

         The term “Biodiversity” has been derived from ‘bio’ and ‘diversity’ . DIVERSITY  means variety within  a species and among species . Biodiversity is a measure of the variety of organisms present in different ecosystem .

The Diversity of plant and animal in a region depends on climate , altitude , soils and the presence of other species . Biodiversity is not distributed evenly on earth . It is richest in topics . Temperate regions also have many species while there are fewer species in the polar regions .

  Biodiversity found on earth today is the result  of 4 billion year of evolution . The origin of life is not well known to science , though limited evidence suggests that until 600 million year ago , all life consisted of becteria and similar unicellular organisms .

IMPORTANCE OF BIODIVERSITY:

Biodiversity provides food for humans . A significant proportion of drugs and derived  directly or indirectly , from biological sources . A wide range of industrial materials e.g building materials , fibres , gums , resins ,  adhesives , rubber and oil are derived directly from plants .

 Biodiversity plays important role in making and maintaining ecosystems. It play a part in regulating the chemistry of our atmosphere and water  supply . Biodiversity is directly involved in recycling nutrients and providing fertile soils .

CLASSIFICATION – AIMS AND PRINCIPLES:

There is  a large collection of very dissimilar forms of organisms, found on earth . Over 1.5 million types of animals and over 0.5 million types of plant are  known to biologists and these are only a small % of the total types estimated to live on earth. They  range in complexity from small and simple bacteria to large and complex human  beings . Some of them live in sea , some on land ; some walk , other fly and still others are stationary . Each has its own way of life e.g getting food , avoiding unfavourable  environmental conditions, finding a place to live , and reproducing its kind . When there are so many diverse kinds of organisms , it becomes  difficult  to learn about the characteristics of each .

 To study  such a large collection , biologists classify the organisms into groups and subgroups  and for this task they require  some system . Biological classification is a method by which biologists divide organisms into group and subgroups

Aims of Classification :

 The branch of biology which deals with classification is called TAXONOMY . And the branch which deals with classification and also traces the evolutionary history of organisms is known as systematic . The main aims of both these branches are ;

   

1.  To determine similarities and differences among organisms so that they can be studied easily .

2. To find the evolutionary relationships among organisms .