22.2
Characteristics and Functions of Blood
Blood is specialized connective tissue comprising about 8% of the body mass. It has a thick, liquid extracellular matrix that contains cells, dissolve…
Approximately 8% of the body mass comprises whole blood, a specialized connective tissue vital for transportation, regulation, and protection.
The presence of cells, dissolved proteins, and electrolytes in the liquid extracellular matrix of blood makes it about five times more viscous than water.
Blood is a warm fluid with a temperature of around 100.4 degrees F and an alkaline pH ranging from 7.35 to 7.45.
Its primary function is to carry oxygen and carbon dioxide between tissues and the lungs.
When saturated with oxygen, it is bright red in color, whereas oxygen-depleted blood is darker.
Blood also transports nutrients from the digestive tract and secretions like hormones from endocrine glands to various tissues.
The proteins and solutes dissolved in the blood serve as buffering agents to regulate the pH of interstitial fluids.
Additionally, it absorbs and redistributes the heat generated by active skeletal muscles.
In case of injury, blood proteins induce clotting to prevent excessive blood loss.
Specialized blood cells can clear foreign particles and secrete proteins, such as antibodies, to protect against disease.
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Q1: What makes blood five times more viscous than water?
Blood's high viscosity results from its composition of cells, dissolved proteins, and electrolytes suspended in a liquid extracellular matrix. These components increase the fluid's density and resistance to flow compared to pure water, making blood approximately five times more viscous than water.
Q2: How does blood regulate pH in the body?
Proteins and solutes dissolved in blood act as buffering agents to maintain the pH of interstitial fluids around the body. Blood maintains an alkaline pH between 7.35 and 7.45, which is critical for proper cellular function and metabolic processes throughout the body's tissues.
Q3: What are the main transport functions of blood?
Blood carries oxygen and carbon dioxide between tissues and the lungs, transports nutrients from the digestive tract, and delivers hormones and other secretions from endocrine glands to target tissues. These transport functions are essential for meeting cellular energy demands and maintaining homeostasis.
Q4: How does blood help prevent excessive bleeding after an injury?
When injury occurs, blood proteins induce clotting to form a plug that prevents excessive blood loss. This clotting response involves the extrinsic and intrinsic pathways of hemostasis, which work together to seal wounds and protect the body from hemorrhage and shock.
Q5: Why does oxygenated blood appear bright red while oxygen-depleted blood is darker?
Blood color depends on oxygen saturation levels in hemoglobin molecules. When saturated with oxygen, blood appears bright red due to the oxygen-bound hemoglobin in red blood cells. Oxygen-depleted blood appears darker because hemoglobin releases oxygen and changes its molecular configuration.
Q6: How does blood protect the body against disease?
Specialized blood cells clear foreign particles and pathogens from circulation throughout the body. These cells also secrete proteins such as antibodies that provide immune defense against disease-causing organisms, forming a critical component of the body's innate and adaptive immune responses.
Q7: What role does blood play in temperature regulation?
Blood absorbs and redistributes heat generated by active skeletal muscles throughout the body. This heat distribution function helps maintain stable core body temperature around 100.4 degrees Fahrenheit, which is essential for optimal enzyme activity and metabolic function in all tissues.