Comparative Haematology
Part I
Haematology
code 605
Different Blood in animal life
Do all animals have red blood cells?
Not all forms of animal life have red blood. A notable exception is found.
Blood and Haemolymph
§One of the major characteristics of life is circulation.
§Animals with backbones, the fluid that circulates within the body is called blood.
§In invertebrates, this fluid is known as hemolymph.
The difference between blood and haemolymph
§ Blood ---liquid flowing (nutrients and oxygen) in the bodies of vertebrates,
it is colored red by haemoglobin, is conveyed by arteries and veins pumped by the heart & generated By Bone Marrow.
While, Haemolymph is a circulating fluid in the bodies of Invertebrates and bathes tissues within exoskeleton.
Hemolymph is mostly water, plus various other odds like amino acids, ions, lipids (fats), carbohydrates, etc., as well as some pigments, but these are rarely very strongly colored. Typical colors for hemolymph itself are greenish or yellowish. There are also some cells, called hemocytes, that float around in the hemolymph, but they are part of an animal’s immune system.
Oxygen-transport proteins
Hemocyanins (Hc) are proteins that transport oxygen throughout the bodies of some invertebrate animals. These metalloproteins contain two copper atoms that reversibly bind a single oxygen molecule (O2). They are second only to hemoglobin in frequency of use as an oxygen transport molecule. Unlike the hemoglobin in red blood cells found in vertebrates, hemocyanins are not bound to blood cells but are instead suspended directly in the hemolymph. Oxygenation causes a color change between the colorless Cu(I) deoxygenated form and the blue Cu(II) oxygenated form as Mollusca and Arthropoda.
Green Blood
Hemocyanins (Hc) are proteins that transport oxygen throughout the bodies of some invertebrate animals. These metalloproteins contain two copper atoms that reversibly bind a single oxygen molecule (O2). They are second only to hemoglobin in frequency of use as an oxygen transport molecule. Unlike the hemoglobin in red blood cells found in vertebrates, hemocyanins are not bound to blood cells but are instead suspended directly in the hemolymph. Oxygenation causes a color change between the colorless Cu(I) deoxygenated form and the blue Cu(II) oxygenated form as Mollusca and Arthropoda (Figure up).
Chlorocrurin
Many invertebrates Contain a chemical in ther blood protein called chlorocruorin, which turns green when oxygenated but will sometimes turn a light red in higher concentrations e.g annelids, marine worms, segmented worms and leeches (segmented worms).
Yellow Blood
Blood plasma is a yellowish coloured liquid component of blood that normally holds the blood cells in whole blood in suspension; this makes plasma the extracellular matrix of blood cells. It makes up about 55% of the body's total blood volume. It is the intravascular fluid part of extracellular fluid (all body fluid outside cells). It is mostly water (up to 95% by volume), and contains dissolved proteins (6–8%) (i.e.— albumins, globulins, and fibrinogen), glucose, clotting factors, electrolytes (Na+, Ca2+, Mg2+, HCO3−, Cl−, etc.), hormones, carbon dioxide (plasma being the main medium for excretory product transportation) and oxygen. Plasma also serves as the protein reserve of the human body. It plays a vital role in an intravascular osmotic effect that keeps electrolyte concentration balanced and protects the body from infection and other blood disorders.
Blood plasma is separated from the blood by spinning a tube of fresh blood containing an anticoagulant in a centrifuge until the blood cells fall to the bottom of the tube. The blood plasma is then poured or drawn off. Blood plasma has a density of approximately 1025 kg/m3, or 1.025 g/ml.
Different Blood in animal life
Do all animals have red blood cells?
Not all forms of animal life have red blood. A notable exception is found.
Blood and Haemolymph
§One of the major characteristics of life is circulation.
§Animals with backbones, the fluid that circulates within the body is called blood.
§In invertebrates, this fluid is known as hemolymph.
The difference between blood and haemolymph
§ Blood ---liquid flowing (nutrients and oxygen) in the bodies of vertebrates,
it is colored red by haemoglobin, is conveyed by arteries and veins pumped by the heart & generated By Bone Marrow.
While, Haemolymph is a circulating fluid in the bodies of Invertebrates and bathes tissues within exoskeleton.
Hemolymph is mostly water, plus various other odds like amino acids, ions, lipids (fats), carbohydrates, etc., as well as some pigments, but these are rarely very strongly colored. Typical colors for hemolymph itself are greenish or yellowish. There are also some cells, called hemocytes, that float around in the hemolymph, but they are part of an animal’s immune system.
Oxygen-transport proteins
Hemocyanins (Hc) are proteins that transport oxygen throughout the bodies of some invertebrate animals. These metalloproteins contain two copper atoms that reversibly bind a single oxygen molecule (O2). They are second only to hemoglobin in frequency of use as an oxygen transport molecule. Unlike the hemoglobin in red blood cells found in vertebrates, hemocyanins are not bound to blood cells but are instead suspended directly in the hemolymph. Oxygenation causes a color change between the colorless Cu(I) deoxygenated form and the blue Cu(II) oxygenated form as Mollusca and Arthropoda.
Green Blood
Hemocyanins (Hc) are proteins that transport oxygen throughout the bodies of some invertebrate animals. These metalloproteins contain two copper atoms that reversibly bind a single oxygen molecule (O2). They are second only to hemoglobin in frequency of use as an oxygen transport molecule. Unlike the hemoglobin in red blood cells found in vertebrates, hemocyanins are not bound to blood cells but are instead suspended directly in the hemolymph. Oxygenation causes a color change between the colorless Cu(I) deoxygenated form and the blue Cu(II) oxygenated form as Mollusca and Arthropoda (Figure up).
Chlorocrurin
Many invertebrates Contain a chemical in ther blood protein called chlorocruorin, which turns green when oxygenated but will sometimes turn a light red in higher concentrations e.g annelids, marine worms, segmented worms and leeches (segmented worms).
Yellow Blood
Blood plasma is a yellowish coloured liquid component of blood that normally holds the blood cells in whole blood in suspension; this makes plasma the extracellular matrix of blood cells. It makes up about 55% of the body's total blood volume. It is the intravascular fluid part of extracellular fluid (all body fluid outside cells). It is mostly water (up to 95% by volume), and contains dissolved proteins (6–8%) (i.e.— albumins, globulins, and fibrinogen), glucose, clotting factors, electrolytes (Na+, Ca2+, Mg2+, HCO3−, Cl−, etc.), hormones, carbon dioxide (plasma being the main medium for excretory product transportation) and oxygen. Plasma also serves as the protein reserve of the human body. It plays a vital role in an intravascular osmotic effect that keeps electrolyte concentration balanced and protects the body from infection and other blood disorders.
Blood plasma is separated from the blood by spinning a tube of fresh blood containing an anticoagulant in a centrifuge until the blood cells fall to the bottom of the tube. The blood plasma is then poured or drawn off. Blood plasma has a density of approximately 1025 kg/m3, or 1.025 g/ml.
Animals with yellow Blood
Some animals, such as the sea cucumbers, even have yellow blood. What could make blood yellow? The yellow coloration is due to a high concentration of the yellow vanadium-based pigment, vanabin. Unlike hemoglobin and hemocyanin, vanabin does not seem to be involved in oxygen transport. In addition to vanabin, sea cucumbers have enough hemocyanin in their blood to sustain their oxygen needs. Actually, the role of vanabin remains a bit of a mystery.
Some animals, such as the sea cucumbers, even have yellow blood. What could make blood yellow? The yellow coloration is due to a high concentration of the yellow vanadium-based pigment, vanabin. Unlike hemoglobin and hemocyanin, vanabin does not seem to be involved in oxygen transport. In addition to vanabin, sea cucumbers have enough hemocyanin in their blood to sustain their oxygen needs. Actually, the role of vanabin remains a bit of a mystery.
Beetles, sea aquirts, sea cucumber have a reatively high concentration of vanabin in their blood, which contains the chemical vanadium, which turns yellow when oxygenated, Vanbin does not aid in the transport of oxygen through the body, and its purpose is still a mystery to scientists.
Purple blood
Brachiopods, penis worms, peanut worms and some other types of marine worms rely on the blood proteins hemerythrin to transport oxygen throughout their bodies. When oxygenated , hemerythrin turns a violet –pink color.
Brachiopods, penis worms, peanut worms and some other types of marine worms rely on the blood proteins hemerythrin to transport oxygen throughout their bodies. When oxygenated , hemerythrin turns a violet –pink color.
Blue Blood
The animals you are referring to are categorised under Mollusca and Arthropoda classes. Squid, Octopus, Horseshoe crab and certain insects and their larval stages have blue coloured blood.
The reason for the blue colour is that they have the protein 'Haemocyanin' whereas the vertebrates have 'Haemoglobin'. Both these proteins assist in oxygen transport in the body. Haemoglobin has iron molecules to which, when the oxygen molecules bind gives red colour.
The animals you are referring to are categorised under Mollusca and Arthropoda classes. Squid, Octopus, Horseshoe crab and certain insects and their larval stages have blue coloured blood.
The reason for the blue colour is that they have the protein 'Haemocyanin' whereas the vertebrates have 'Haemoglobin'. Both these proteins assist in oxygen transport in the body. Haemoglobin has iron molecules to which, when the oxygen molecules bind gives red colour.
In the case of Haemocyanin, it has copper molecules instead of iron and when the oxygen molecules bind to copper molecules of Haemocyanin it becomes blue colour. After dissociation of copper and oxygen molecules (exhalation) the Haemocyanin becomes colourless.
Another difference between Haemoglobin and Haemocyanin is that unlike Haemoglobin which binds to the blood cells in animals, Haemocyanin is directly suspended in Haemolymph. Most of the molluscans have blue blood due to the pigment in their blood haemocyanin.
For whom blue blood is the Crustaceans, spiders, squid,octopuses, and some molluscs all have blue blood as a result of having a different respiratory pigment. Rather than haemoglobin, these creatures use a protein called haemocyanin to transport oxygen.
White Blood
While almost all animals with a backbone, called vertebrates, have red blood there are some non vertebrates with blood that is not red. Some insects like beetles and cockroaches have yellowish or white like colorless blood. The same is true for some non vertebrate sea animals like the sea cucumber.
Another difference between Haemoglobin and Haemocyanin is that unlike Haemoglobin which binds to the blood cells in animals, Haemocyanin is directly suspended in Haemolymph. Most of the molluscans have blue blood due to the pigment in their blood haemocyanin.
For whom blue blood is the Crustaceans, spiders, squid,octopuses, and some molluscs all have blue blood as a result of having a different respiratory pigment. Rather than haemoglobin, these creatures use a protein called haemocyanin to transport oxygen.
White Blood
While almost all animals with a backbone, called vertebrates, have red blood there are some non vertebrates with blood that is not red. Some insects like beetles and cockroaches have yellowish or white like colorless blood. The same is true for some non vertebrate sea animals like the sea cucumber.
The ice fish in Antartica have clear blood, they don’t have red blood cells. They don’t need then. In cold water the oxygen content is higher, and because of the cold water the fish have a very low metabolism, so their circulartory system can transport enough oxygen in their plasma.
Not all forms of animal life have red blood. A notable exception is found.
§ Crabs and lobsters have blue blood, and leeches and earthworms have green blood.
§ There also are invertebrates, such as starfish, that have yellow blood.
§ The oxygen in a spider's blood stream is not bound to hemoglobin, as is the case with humans.
§ Instead, the oxygen is bound to hemocyanin, which contains copper rather than the iron that is found in hemoglobin.
§ Invertebrates such as flat worms and jelly fish do not rely on blood to distribute nutrition though the body.
§ These animals are capable of absorbing nutrients through the skin and eliminating waste in a similar manner.
Hemocyanin
§ Hemocyanin (blue) contains copper and is found in crustaceans and mollusks.
Vanabins
§ It is thought that tunicates (sea squirts) might use vanabins (proteins containing vanadium) for respiratory pigment (bright-green, blue, or orange).
§ In many invertebrates, oxygen-carrying proteins are freely soluble in the blood.
§ They are contained in specialized red blood cells, allowing for a higher concentration of respiratory pigments without increasing viscosity or damaging blood filtering organs like the kidneys.
Haemolymph
§ It is a fluid in the circulatory system of arthropods (e.g. spiders, crustaceans) and is analogous to the fluids and cells making up both blood and interstitial fluid (including water, proteins, fats, sugars, hormones, etc.) in vertebrates as mammals.
§ Hemolymph fills all of the interior (the hemocoel) of the animal's body and surrounds all cells.
§ It contains hemocyanin, a copper-based protein that turns blue in color when oxygenated, instead of the iron-based hemoglobin in red blood cells found in vertebrates, thus giving hemolymph a blue-green color rather than the red color of vertebrate blood.
§ When not oxygenated, hemolymph quickly loses its color and appears grey.
§ The hemolymph of lower arthropods, is not used for oxygen transport because these animals respirate directly from their body surfaces (internal and external) to air, but it does contain nutrients such as proteins and sugars.
Mollusks & Arthropodes
§ The blood of most mollusks and as well as some arthropods is blue, as it contains the copper-containing protein hemocyanin at concentrations of about 50 g./L.
§ Hemocyanin is colorless when deoxygenated and dark blue when oxygenated.
Marine invertebrates
§ Hemerythrin is used for oxygen transport in the marine invertebrates sipunculids, priapulids, brachiopods, and the annelid worm.
§ Hemerythrin is violet-pink when oxygenated.
Sea Cucumbers
§ The hemolymph of sea cucumbers, contains vanabins (vanadium containing protein).
§ It is 100 times higher than the surrounding sea water.
§ It is not clear whether these vanabins actually carry oxygen. When exposed to oxygen, however, vanabins turn a mustard yellow.
Fish ( Rainbow ) blood
§ Fish blood (Rainbow Trout) seems to have nuclei in their red blood cells.
Description of Fish Blood Cell Morphology
§ Fish erythrocytes are oval in shape with abundant smooth eosinophilic cytoplasm and a central, oval-shaped condensed nucleus.
Thrombocytes
§ Typical fish thrombocytes closely resemble those found in avian and reptilian species; they are small oval cells with clear, colorless cytoplasm and a central oval, condensed nucleus.
§ Crabs and lobsters have blue blood, and leeches and earthworms have green blood.
§ There also are invertebrates, such as starfish, that have yellow blood.
§ The oxygen in a spider's blood stream is not bound to hemoglobin, as is the case with humans.
§ Instead, the oxygen is bound to hemocyanin, which contains copper rather than the iron that is found in hemoglobin.
§ Invertebrates such as flat worms and jelly fish do not rely on blood to distribute nutrition though the body.
§ These animals are capable of absorbing nutrients through the skin and eliminating waste in a similar manner.
Hemocyanin
§ Hemocyanin (blue) contains copper and is found in crustaceans and mollusks.
Vanabins
§ It is thought that tunicates (sea squirts) might use vanabins (proteins containing vanadium) for respiratory pigment (bright-green, blue, or orange).
§ In many invertebrates, oxygen-carrying proteins are freely soluble in the blood.
§ They are contained in specialized red blood cells, allowing for a higher concentration of respiratory pigments without increasing viscosity or damaging blood filtering organs like the kidneys.
Haemolymph
§ It is a fluid in the circulatory system of arthropods (e.g. spiders, crustaceans) and is analogous to the fluids and cells making up both blood and interstitial fluid (including water, proteins, fats, sugars, hormones, etc.) in vertebrates as mammals.
§ Hemolymph fills all of the interior (the hemocoel) of the animal's body and surrounds all cells.
§ It contains hemocyanin, a copper-based protein that turns blue in color when oxygenated, instead of the iron-based hemoglobin in red blood cells found in vertebrates, thus giving hemolymph a blue-green color rather than the red color of vertebrate blood.
§ When not oxygenated, hemolymph quickly loses its color and appears grey.
§ The hemolymph of lower arthropods, is not used for oxygen transport because these animals respirate directly from their body surfaces (internal and external) to air, but it does contain nutrients such as proteins and sugars.
Mollusks & Arthropodes
§ The blood of most mollusks and as well as some arthropods is blue, as it contains the copper-containing protein hemocyanin at concentrations of about 50 g./L.
§ Hemocyanin is colorless when deoxygenated and dark blue when oxygenated.
Marine invertebrates
§ Hemerythrin is used for oxygen transport in the marine invertebrates sipunculids, priapulids, brachiopods, and the annelid worm.
§ Hemerythrin is violet-pink when oxygenated.
Sea Cucumbers
§ The hemolymph of sea cucumbers, contains vanabins (vanadium containing protein).
§ It is 100 times higher than the surrounding sea water.
§ It is not clear whether these vanabins actually carry oxygen. When exposed to oxygen, however, vanabins turn a mustard yellow.
Fish ( Rainbow ) blood
§ Fish blood (Rainbow Trout) seems to have nuclei in their red blood cells.
Description of Fish Blood Cell Morphology
§ Fish erythrocytes are oval in shape with abundant smooth eosinophilic cytoplasm and a central, oval-shaped condensed nucleus.
Thrombocytes
§ Typical fish thrombocytes closely resemble those found in avian and reptilian species; they are small oval cells with clear, colorless cytoplasm and a central oval, condensed nucleus.
Avian Blood Cells
In avian species, mature red blood cells are oval cells with a central nucleus that stains dark blue with specific stain. The cytoplasm normally stains a pink-orange color. Young RBCs begin as round cells that have a medium blue nucleus and light blue cytoplasm as erythrocytes of rainbow fish (Figure).
Reptile Blood
Reptilian erythrocytes are nucleated and may stay in the peripheral circulation for several years. They are elliptic and have a centrally located, basophilic nucleus. cytoplasm is translucent and light pink-orange.
The Mammalian Red Blood Cell
The normal mammalian red blood cell takes the shape of a biconcave disc, approximately 7 - 8 micometers in diameter. The cytoplasm of the mature mammalian red cell consists of nothing more than an aqueous solution of simple inorganic and organic molecules and macromolecules, with a high concentartion of the protein hemoglobin.
The mature cell contains no internal membranous structures. That is, the mature cell has no nucleus and no organelles. As red blood cells develop and mature in bone marrow, the nucleus and organelles completely deteriorate. This is, of course, by design. Mature red blood cells must be able to squeeze through the smallest capillaries; the nucleus and organelles would interfere with this.
Camel's Blood
§ The red blood cells in camel are oval . Due to the oval shape, their blood cells are able to expand to 240% of its original volume, whereas the red blood cells of other animals can only expand up to 150% .
§ This allows the camels to drink up to 30 gallons of water in 13 minutes to recover from dehydration. This elongated shape of their red blood cells also allow the ease of traveling in thick blood and narrow blood vessels during dehydration. Their hemoglobin also have a higher affinity for oxygen than other domestic mammals.
Like all mammals, camel red blood cells are without a nucleus. This is a very useful adaptation to increase oxygen carrying potential.
Warm-Blooded & Cold-Blooded
§ With a few exceptions, all mammals and birds are warm-blooded, while, reptiles, insects, amphibians and fish are cold-blooded.
§ The temperature of an animal's blood is related to its body temperature.
Warm-Blooded Animals
§ Warm-blooded animals do this by generating their own heat when they are in a cooler environment, and by cooling themselves when they are in a hotter environment.
§ To stay cool, warm-blooded animals sweat to loose heat by water evaporation.
§ Primates, such as humans and monkey, have sweat glands all over their bodies.
§ Dogs and cats have sweat glands only on their feet.
Cold-Blooded Animals
§ Cold-blooded creatures take on the temperature of their surroundings.
§ They are hot when their environment is hot and cold when their environment is cold.
§ In hot environments, cold-blooded animals can have blood that is much warmer than warm-blooded animals.
§ Cold-blooded animals are much more active in warm environments and are very sluggish in cold environments.
§ This is because their muscle activity depends on chemical reactions which run quickly when it is hot and slowly when it is cold.
§ A cold-blooded animal can convert much more of its food into body mass compared with a warm-blooded animal.
Advantages and Disadvantages
There are many advantages to being warm-blooded.
§ Warm-blooded animals can remain active in cold environments.
§ But cold-blooded animals can hardly move.
§ Warm-blooded animals can live in almost any surface environment on Earth, like in arctic regions or on high mountains
where
§ most cold-blooded animals would have difficulty surviving.
§ Warm-blooded animals can remain active, seek food, and defend themselves in a wide range of outdoor temperatures.
§ Cold-blooded animals can only do this when they are warm enough.
§ A cold-blooded animal's level of activity depends upon the temperature of its surroundings.
§ A reptile, for example, will increase its body temperature before hunting and is better able to escape predators when it is warm.
§ Cold-blooded animals also need to be warm and active to find a mate and reproduce.
§ Being cold-blooded, however, also has its advantages.
§ Cold-blooded animals require much less energy to survive than warm-blooded animals do.
§ Mammals and birds require much more food and energy than do cold-blooded animals of the same weight.
Heat according Surface area and Mass Of the Body
Human Blood
Haemoglobin
The Hb molecule is a tetramer consisting of 4 polypeptide chains (globins).
• 2 α chains that are each 141 a.a.long
• 2 ß chains that are each 146 a.a.long
• Attached to each chain is an iron (haem).
§ Cold-blooded creatures take on the temperature of their surroundings.
§ They are hot when their environment is hot and cold when their environment is cold.
§ In hot environments, cold-blooded animals can have blood that is much warmer than warm-blooded animals.
§ Cold-blooded animals are much more active in warm environments and are very sluggish in cold environments.
§ This is because their muscle activity depends on chemical reactions which run quickly when it is hot and slowly when it is cold.
§ A cold-blooded animal can convert much more of its food into body mass compared with a warm-blooded animal.
Advantages and Disadvantages
There are many advantages to being warm-blooded.
§ Warm-blooded animals can remain active in cold environments.
§ But cold-blooded animals can hardly move.
§ Warm-blooded animals can live in almost any surface environment on Earth, like in arctic regions or on high mountains
where
§ most cold-blooded animals would have difficulty surviving.
§ Warm-blooded animals can remain active, seek food, and defend themselves in a wide range of outdoor temperatures.
§ Cold-blooded animals can only do this when they are warm enough.
§ A cold-blooded animal's level of activity depends upon the temperature of its surroundings.
§ A reptile, for example, will increase its body temperature before hunting and is better able to escape predators when it is warm.
§ Cold-blooded animals also need to be warm and active to find a mate and reproduce.
§ Being cold-blooded, however, also has its advantages.
§ Cold-blooded animals require much less energy to survive than warm-blooded animals do.
§ Mammals and birds require much more food and energy than do cold-blooded animals of the same weight.
Heat according Surface area and Mass Of the Body
- This is because in warm-blooded animals, the heat loss from their bodies is proportional to the surface area of their bodies, while the heat created by their bodies is proportional to their mass.
- The ratio of a body's surface area to its mass is less the larger the animal is.
- This means that larger warm-blooded animals can generate more heat than they loose and more easily keep their body temperatures stable.
- Smaller warm-blooded animals loose heat more quickly.
- Many cold-blooded animals will try to keep their body temperatures as low as possible when food is scarce.
- Another disadvantage to being warm-blooded is that warm-blooded bodies provide an nice warm environment for viruses, bacteria and parasites to live in.
- Mammals and birds tend to have more problems with these infections than do reptiles, whose constantly changing body temperatures make life more difficult for these invaders.
- However, an advantage of this is that mammals and birds have developed a stronger immune system than cold-blooded animals.
- A reptile's immune system is more efficient when the animals is warmer, however, since bacteria probably grow more slowly in lower temperatures, reptiles sometimes lower their body temperatures when they have an infection.
Human Blood
- Suspension of special cells in a liquid called plasma. It is about 1/12th /body weight (5-6 litres). It consists of 55 % plasma, and 45 % cells.
- They lack organelles as nuclei and mitochondria, they cannot be considered as true cells.
- Number Of R.B.Cs ranged between 4.5- 6 million/ c mm. of blood. Its side view shows biconcaved discs. These increase the efficiency of diffusion of O2 and CO2 .
- R.B.Cs (7um) have a flexible plasma membrane. This allows to squeeze through capillaries as small as 3 um wide. Because lack a nucleus and other cellular machinery. Erythrocytes cannot repair themselves when damaged. Consequently its life span 120 days.
Haemoglobin
The Hb molecule is a tetramer consisting of 4 polypeptide chains (globins).
• 2 α chains that are each 141 a.a.long
• 2 ß chains that are each 146 a.a.long
• Attached to each chain is an iron (haem).
- O2 is transported in combination with the iron molecule of the haem group. This is an oxygenation reaction, not an oxidation.
Importance Of Iron
Iron is important for formation of hemoglobin
- Myoglobin
- Cytochromes
- Cytochrome oxidase
- Peroxidase
- Catalase.
Iron Metabolism
· Its average in the body between 4-5 grams , 65% presentv in the form of haemoglobin.
· About 4% in the form of myoglobin, 1% in the form of different heme compounds that promote intracellular oxidation, 0.1% combined with protein transferrin in the plasma.
· 15-30% stored in the liver in the form of ferritin.
· Iron absorbed in doudenum of combines with blood plasma with beta-globulin (apotransferrin) to form transferrin.
· It released to any tissue cells but especially to liver hepatocytes and less to reticuloendothelial cells of bone marrow.
· In the cell cytoplasm , it combines with protein, apoferritin to form ferritin (storage iron).
Diseases of Iron Disturbance
· Iron overload (hemochromatosis)
· Iron deficiency (iron deficiency anemia).
Body Iron Stores
• The liver's stores of ferritin (the primary physiologic reserve iron in the body.
• Women who must use their stores to compensate for iron lost through menstruation, pregnancy or lactation.
Delivery of Iron Into Erythroblasts
Transferrin molecule:
- · binds strongly with receptors in the cell membranes of erythroblasts in the bone marrow.
- · it is ingested into the erythroblasts by endocytosis.
- · transferrin delivers the iron directly to the mitochondria where heme is synthesized.
- · In persons who do not have adequate quantities of transferrin in their blood failure to transport iron to the erythroblasts cause severe hypochromic anemia- that is decreased numbers of R.B.Cs containing less Hb than normal.
How the Body Gets Its Iron
When r.b.cs have lived their life span. They are destroyed, Hb released from the cells. They ingested by the cells of monocytes-macrophage- system. free iron is liberated. it is either stored in the ferritin pool or reused for new hemoglobin.
Daily loss of iron
· About 1 mg of iron is excreted each day by men, mainly into feces.
· Additional quantities of iron are lost whenever bleeding occurs.
· In women, the menstrual loss of blood, in which the iron value approximately 2mg/day.
Iron Absorption
- Iron absorption occurs predominantly in the duodenum and upper jejunum.
- A feedback mechanism exists that enhances iron absorption in people who are iron deficient.
- At physiological pH, ferrous iron (Fe2+) is rapidly oxidized to the insoluble ferric (Fe3+) form.
- Gastric acid lowers the pH in the proximal duodenum, enhancing the solubility and uptake of ferric iron. When gastric acid production is impaired iron absorption is reduced substantially.
- Heme is absorbed by machinery completely different to that of inorganic iron.
- The process is more efficient and is independent of duodenal pH . Consequently meats are excellent nutrient sources of iron.
- Blockade of heme catabolism in the intestine by a heme oxygenase inhibitor can produce iron deficiency.
- The little of meats in the diets of many of the people leads to the iron deficiency.
- Ascorbate and citrate increase iron uptake in part by acting as weak chelators to help to solubilize the metal in the duodenum.
- Conversely, iron absorption is inhibited by plant phytates and tannins. These compounds also chelate iron, but prevent its uptake by the absorption machinery.
- Phytates are prominent in wheat and some other cereals, while tannins are prevalent in teas.
- Lead is a particularly pernicious element to iron metabolism.
- Lead is taken up by the iron absorption machinery, and secondarily blocks iron through competitive inhibition.
- lead not only produces anemia, but can impair cognitive development.
- Lead exists naturally at high levels in ground water and soil in some regions, and can attack children's health.
Mechanism of Iron Absorption
- The mechanism by which iron enters the mucosal cells lining the upper gastrointestinal tract is unknown.
- Most cells in the rest of the body are believed to acquire iron from plasma transferrin (an iron-protein chelate), via specific transferrin receptors and receptor-mediated endocytosis.
- Like most mineral nutrients, the majority of the iron absorbed from digested food or supplements is absorbed in the duodenum by enterocytes of the duodenal lining.
- To be absorbed, dietary iron can be absorbed as part of a protein such as heme protein or must be in its ferrous Fe2+ form.
- A ferric reductase enzyme on the enterocytes' brush border, reduces ferric Fe3+ to Fe2+.
- A protein called divalent metal transporter 1 DMT1, which transports all kinds of divalent metals into the body, then transports the iron across the enterocyte's cell membrane and into the cell.
Iron Toxicity
- Iron is also necessary for many metabolic functions because of its unique reactions with oxygen.
- But with too much iron, the oxygenation reactions can run out of control, releasing free radicals that effectively burn from the inside out.
(1) Lowered intelligence:
- In the nervous system, iron and oxygen react with certain fatty acids in nerve cell membranes.
- This can not only damage the affected nerve cell but also trigger inflammation and repair mechanisms that can lead to headaches and cause blood clots and swelling that can extend to nearby tissues, disrupting brain function.
(2) Bacterial infection:
- Bad bacteria love iron. Iron in the gut can promote the growth of pathogenic bacteria. Only 5% of the iron is absorbed from the gut when the source is cereals, compared to 50% of the iron being absorbed from breastmilk.
- This leaves an abnormally high amount of unabsorbed iron in the gut to promote the growth of pathogens that cause intestinal and even blood infection, and disrupt immune function for some time after the infection is gone.
(3) Early Atherosclerosis:
- Iron and oxygen react with certain fatty acids in fat-carrying blood particles lipoproteins (HDL and LDL cholesterol).
- The reaction damages the particles so that they can’t be recognized by the body. The unfamiliar particles never bind to the docking sites on that allow lipoproteins to unload their nutrient cargo (nutrients like phospholipids, vitamins A, D, E, and K).
(4) Cancer:
- Iron and oxygen react with a wide variety of chemicals in the cell nucleus to generate dangerous free radicals.
- Free radicals are high energy particles that, like X-Rays, can damage DNA leading to cancer.
(5) Stunted growth:
- Excess iron leads to body-wide skeletal growth delays, including the skull and long bones.
- It may be that all this disruption burns up valuable nutrients that may no longer be able to support normal skeletal growth.
In Bird
§ In contrast to mammalian erythrocytes, which have lost their nucleus and mitochondria during maturation, the erythrocytes of almost all other vertebrate species are nucleated throughout their lifespan.
In Camel
§ Camel RBCs are without a nucleus, like all mammals , but they have an oval shape.
The red blood cells of the dromedary camel protect it from dehydration because the oval-shaped cells can circulate even in thick blood significantly.
§ The dromedary camel is incredibly well-adapted to hot, arid climates.
§ The camel can go days without drinking water, surviving extreme dehydration and safely losing 40% of its body weight in water.
§ This ability is, in part, due to uniquely oval red blood cells (which carry oxygen).
§ Additionally, the camel’s red blood cells are capable of expanding up to 240% of their original volume without rupturing; most animals’ cells can expand only 150%.
§ This makes it possible for the camel to drink the necessarily large amount of water to recover from dehydration.