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Blood and Circulation Physiology
Blood consists of lymph and tissue fluid, the body's internal medium. The connection between the external environment and the body's cells in higher animals is achieved through the blood. The body cells are not in direct contact with the blood, but rather with the tissue fluid that filters from the blood through the walls of the capillaries and is located in the intercellular spaces. The exchange of substances between the blood and the tissues is carried out.
This is evident in the capillary system, where the exchange of gases and nutrients absorbed through the digestive system and metabolic byproducts takes place.
The rapid exchange of substances between the blood and tissues is attributed to the red blood cells, whose shape and huge number are responsible for creating a large surface area capable of carrying various substances arriving in the blood. The main function of the red blood cell is to transport oxygen to a large extent and carbon dioxide. It also absorbs nutrients and carries them on its outer surface towards various tissues and organs, and in return, it receives substances coming out of those tissues and organs.
Blood consists of lymph and tissue fluid, the body's internal medium. The connection between the external environment and the body's cells in higher animals is achieved through the blood. The body cells are not in direct contact with the blood, but rather with the tissue fluid that filters from the blood through the walls of the capillaries and is located in the intercellular spaces. The exchange of substances between the blood and the tissues is carried out.
This is evident in the capillary system, where the exchange of gases and nutrients absorbed through the digestive system and metabolic byproducts takes place.
The rapid exchange of substances between the blood and tissues is attributed to the red blood cells, whose shape and huge number are responsible for creating a large surface area capable of carrying various substances arriving in the blood. The main function of the red blood cell is to transport oxygen to a large extent and carbon dioxide. It also absorbs nutrients and carries them on its outer surface towards various tissues and organs, and in return, it receives substances coming out of those tissues and organs.
Blood performs the following main physiological functions
Respiration is the process of carrying oxygen from the lungs to the tissues and carbon dioxide from the tissues to the lungs.
Transportation : The blood receives nutrients from the digestive tract and carries them to the tissues and organs, and transports metabolites (such as lactic acid from the muscles to the liver).
Excretion: The blood receives the end products of vital processes and carries them to the excretory organs (kidneys, lungs, liver, intestines and skin) to be excreted outside the body.
Regulatory , the blood supplies tissues and organs with hormones secreted by the endocrine glands and vitamins, and regulates osmotic pressure, normal water content and temperature.
In terms of defense , the blood performs several defensive functions, including phagocytic cells, which are specialized cells such as phagocytic cells.
Respiration is the process of carrying oxygen from the lungs to the tissues and carbon dioxide from the tissues to the lungs.
Transportation : The blood receives nutrients from the digestive tract and carries them to the tissues and organs, and transports metabolites (such as lactic acid from the muscles to the liver).
Excretion: The blood receives the end products of vital processes and carries them to the excretory organs (kidneys, lungs, liver, intestines and skin) to be excreted outside the body.
Regulatory , the blood supplies tissues and organs with hormones secreted by the endocrine glands and vitamins, and regulates osmotic pressure, normal water content and temperature.
In terms of defense , the blood performs several defensive functions, including phagocytic cells, which are specialized cells such as phagocytic cells.
Blood Volume
The amount of blood varies among different animal species and is relatively constant in animals of the same species. The amount of blood depends on several factors, including age, sex, training, season, nutrition, and altitude above sea level.
Young animals contain relatively more blood than older animals. Newborn animals have about 100 ml/kg of body weight, and this is higher in males than in females. The blood volume increases in animals that live in areas high above sea level due to the increased number of red blood cells in their blood.
The amount of blood varies among different animal species and is relatively constant in animals of the same species. The amount of blood depends on several factors, including age, sex, training, season, nutrition, and altitude above sea level.
Young animals contain relatively more blood than older animals. Newborn animals have about 100 ml/kg of body weight, and this is higher in males than in females. The blood volume increases in animals that live in areas high above sea level due to the increased number of red blood cells in their blood.
General properties and composition of blood
Blood is a special fluid composed of two parts: the first is liquid (plasma), and the second is cellular (red and white blood cells and platelets). Its color is opaque red with a salty taste and a distinctive odor due to the presence of volatile fatty acids. The color of blood changes depending on the degree of oxygen saturation. Oxygenated blood (arterial blood) is bright red, while deoxygenated blood (venous blood) is dark red. Blood color also changes in cases of high cholesterol or low blood cell count.
Blood viscosity arises from the internal friction of small particles as they move. Blood viscosity depends on the shape and number of red blood cells; the higher the number of red blood cells, the greater the viscosity.
Blood is a special fluid composed of two parts: the first is liquid (plasma), and the second is cellular (red and white blood cells and platelets). Its color is opaque red with a salty taste and a distinctive odor due to the presence of volatile fatty acids. The color of blood changes depending on the degree of oxygen saturation. Oxygenated blood (arterial blood) is bright red, while deoxygenated blood (venous blood) is dark red. Blood color also changes in cases of high cholesterol or low blood cell count.
Blood viscosity arises from the internal friction of small particles as they move. Blood viscosity depends on the shape and number of red blood cells; the higher the number of red blood cells, the greater the viscosity.
Blood cells and blood corpuscles
When centrifugation is performed with the addition of oxalate or citrate, the blood cells separate from the plasma, with the red blood cells settling to the bottom because they are heavier, followed by a thin layer of white blood cells, and then the plasma to the top. The volume of blood cells is approximately (32-46%) and plasma (54-68%).
When centrifugation is performed with the addition of oxalate or citrate, the blood cells separate from the plasma, with the red blood cells settling to the bottom because they are heavier, followed by a thin layer of white blood cells, and then the plasma to the top. The volume of blood cells is approximately (32-46%) and plasma (54-68%).
Red blood cells (erythrocytes)
Red blood cells constitute the basis or the largest part of blood cells and have nuclei in birds, fish, amphibians, and reptiles, but they are anucleate in mammals, including humans, as they lose their nuclei during their development. The red blood cell membrane gives it its shape and specificity as a cell when it actually begins to transport gases from the blood.
In mammals, red blood cells are elastic, disc-shaped, round, biconcave (except in camels, where they are oval-shaped). Their shape changes as they pass through the capillaries, but they regain their normal shape when they return to the large blood vessels.
The concavity of the two faces of the red blood cell increases its surface area, allowing hemoglobin to be distributed over a larger area and facilitating gas exchange. Red blood cells contain approximately 60% water and 40% solid matter. Hemoglobin represents 90% of the solid matter, and 10% includes proteins, fats, carbohydrates, and mineral salts.
The red blood cell membrane is composed of proteins and lipids. This membrane is semi-permeable and highly selective, releasing positive ions (Na+ and K+) weakly but readily releasing negative ions (SO4-, HCO3-, and Cl-) and water. Red blood cells are negatively charged, and their size varies between species and even between animals of the same species.
The number of red blood cells depends on several factors, including: food, weather, season, physiological condition, age, productive status, sex, and other factors. There is a difference between night and day estimated at about (±10%), as well as the availability of iron, copper, vitamin B12, vitamin C, and other substances.
Red blood cells constitute the basis or the largest part of blood cells and have nuclei in birds, fish, amphibians, and reptiles, but they are anucleate in mammals, including humans, as they lose their nuclei during their development. The red blood cell membrane gives it its shape and specificity as a cell when it actually begins to transport gases from the blood.
In mammals, red blood cells are elastic, disc-shaped, round, biconcave (except in camels, where they are oval-shaped). Their shape changes as they pass through the capillaries, but they regain their normal shape when they return to the large blood vessels.
The concavity of the two faces of the red blood cell increases its surface area, allowing hemoglobin to be distributed over a larger area and facilitating gas exchange. Red blood cells contain approximately 60% water and 40% solid matter. Hemoglobin represents 90% of the solid matter, and 10% includes proteins, fats, carbohydrates, and mineral salts.
The red blood cell membrane is composed of proteins and lipids. This membrane is semi-permeable and highly selective, releasing positive ions (Na+ and K+) weakly but readily releasing negative ions (SO4-, HCO3-, and Cl-) and water. Red blood cells are negatively charged, and their size varies between species and even between animals of the same species.
The number of red blood cells depends on several factors, including: food, weather, season, physiological condition, age, productive status, sex, and other factors. There is a difference between night and day estimated at about (±10%), as well as the availability of iron, copper, vitamin B12, vitamin C, and other substances.
hemoglobin
It is considered one of the most important components of red blood cells and is classified as a complex protein. It consists of a colorless protein component, globin (96%), and a heme group (4%) that gives it its characteristic color. The hemoglobin content in the blood depends on several factors, which are almost the same factors that affect the number of red blood cells (race, sex, age, diet, season, productive status, physiological state).
When hemoglobin binds to oxygen, it forms oxyhemoglobin, a fragile, bright red compound. This binding is reversible. When hemoglobin binds to carbon dioxide, it forms carboxyhemoglobin, which is also fragile and releases carbon dioxide upon reaching the lungs.
It is considered one of the most important components of red blood cells and is classified as a complex protein. It consists of a colorless protein component, globin (96%), and a heme group (4%) that gives it its characteristic color. The hemoglobin content in the blood depends on several factors, which are almost the same factors that affect the number of red blood cells (race, sex, age, diet, season, productive status, physiological state).
When hemoglobin binds to oxygen, it forms oxyhemoglobin, a fragile, bright red compound. This binding is reversible. When hemoglobin binds to carbon dioxide, it forms carboxyhemoglobin, which is also fragile and releases carbon dioxide upon reaching the lungs.
Leukocytes (white blood cells)
They play an important role in the defensive functions and recovery of the organism’s body. Their main functions are phagocytosis, antibody production, secretion, and breakdown of toxins from the protein source. White blood cells are larger than red blood cells, have no color, and have the ability to move and pass through the thin walls of capillaries, where they enter the spaces between tissues by forming pseudopodia.
The number of white blood cells depends on the animal's species, breed, age, nutrition, physiological state, and disease. An increase in white blood cell count above the normal range is known as leukocytosis, and a decrease is known as leukopenia. White blood cell counts rise during and after feeding, during pregnancy, in cases of acute physical exertion, fear, and in inflammatory conditions.
White blood cells can be classified, based on the origin and structure of their nucleus and protoplasm, into:
Granulocytes and agranulocytes, where in granulocytes there are distinct granules that have the ability to stain with basic and acidic dyes.
They play an important role in the defensive functions and recovery of the organism’s body. Their main functions are phagocytosis, antibody production, secretion, and breakdown of toxins from the protein source. White blood cells are larger than red blood cells, have no color, and have the ability to move and pass through the thin walls of capillaries, where they enter the spaces between tissues by forming pseudopodia.
The number of white blood cells depends on the animal's species, breed, age, nutrition, physiological state, and disease. An increase in white blood cell count above the normal range is known as leukocytosis, and a decrease is known as leukopenia. White blood cell counts rise during and after feeding, during pregnancy, in cases of acute physical exertion, fear, and in inflammatory conditions.
White blood cells can be classified, based on the origin and structure of their nucleus and protoplasm, into:
Granulocytes and agranulocytes, where in granulocytes there are distinct granules that have the ability to stain with basic and acidic dyes.
Based on their pigments, granulocytes (white blood cells) are divided into:
1- Basophils, which are spherical or oval cells, few in number and almost rare (0.5-1%). Their cytoplasm contains granules with an affinity for basic pigments. They do not perform phagocytosis but transport nutrients and participate in the formation of heparin.
2- Eosinophils, which are large spherical cells, few in number, and have granules that accept acidic dyes such as red eosin. Their nucleus consists of two lobes arranged in the shape of the letter S. Eosinophils have weak phagocytic activity and secrete enzymes that have the ability to break down foreign bodies.
3- Neutrophils, which constitute the highest percentage of granulocytes, and their cytoplasm is clearly granular. They have an affinity for both basic and acidic stains and have a nucleus with 3-5 lobes.
Agranulocytes are cells that do not have granules in their cytoplasm and have a large, spherical nucleus. They include:
Lymphocytes: They are formed in the lymph nodes and spleen, and their nucleus is oval.
Monocytes: They are the largest blood cells, spherical in shape, and their nucleus resembles the shape of a kidney. They have the ability to engulf foreign bodies.
1- Basophils, which are spherical or oval cells, few in number and almost rare (0.5-1%). Their cytoplasm contains granules with an affinity for basic pigments. They do not perform phagocytosis but transport nutrients and participate in the formation of heparin.
2- Eosinophils, which are large spherical cells, few in number, and have granules that accept acidic dyes such as red eosin. Their nucleus consists of two lobes arranged in the shape of the letter S. Eosinophils have weak phagocytic activity and secrete enzymes that have the ability to break down foreign bodies.
3- Neutrophils, which constitute the highest percentage of granulocytes, and their cytoplasm is clearly granular. They have an affinity for both basic and acidic stains and have a nucleus with 3-5 lobes.
Agranulocytes are cells that do not have granules in their cytoplasm and have a large, spherical nucleus. They include:
Lymphocytes: They are formed in the lymph nodes and spleen, and their nucleus is oval.
Monocytes: They are the largest blood cells, spherical in shape, and their nucleus resembles the shape of a kidney. They have the ability to engulf foreign bodies.
Blood platelets (Thrombocytes)
These are spindle-shaped or spherical platelets without a nucleus that have an important defensive function, especially in blood clotting processes, when they accumulate on the surface of the injured or cut area outside the blood vessel. They break down quickly, and as a result, the clotting process begins and fibrin threads that form the clot are formed.
These are spindle-shaped or spherical platelets without a nucleus that have an important defensive function, especially in blood clotting processes, when they accumulate on the surface of the injured or cut area outside the blood vessel. They break down quickly, and as a result, the clotting process begins and fibrin threads that form the clot are formed.
Blood formation
Blood cells are produced in the body's hematopoietic organs, namely the bone marrow, lymph nodes, and spleen. The bone marrow produces red blood cells, white blood cells (granulocytes), and platelets, while the spleen produces lymph nodes. For normal red blood cell production to occur, nutrients, especially proteins, must be continuously available. Certain endocrine glands, such as the pituitary and thyroid glands, also play a role in red blood cell formation. Insufficient oxygen and blood loss can stimulate red blood cell production.
Blood cells are produced in the body's hematopoietic organs, namely the bone marrow, lymph nodes, and spleen. The bone marrow produces red blood cells, white blood cells (granulocytes), and platelets, while the spleen produces lymph nodes. For normal red blood cell production to occur, nutrients, especially proteins, must be continuously available. Certain endocrine glands, such as the pituitary and thyroid glands, also play a role in red blood cell formation. Insufficient oxygen and blood loss can stimulate red blood cell production.
