Blood Composition and Function Study Pack

Kibin's free study pack on Blood Composition and Function includes a 4-section study guide, 8 quiz questions, 10 flashcards, and 1 open-ended Explain review question. Sign up free to track your progress toward mastery, plus upload your own notes and recordings to create personalized study packs organized by course.

Last updated May 21, 2026

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Blood Composition and Function Study Guide

Break down the cellular and chemical makeup of blood, from plasma proteins like albumin and their role in oncotic pressure to the oxygen-carrying mechanics of hemoglobin. This pack covers erythrocytes, the five types of leukocytes, platelet-driven hemostasis, and hematocrit values used to diagnose anemia and polycythemia — everything you need for a thorough understanding of blood composition and function.

Key Takeaways

  • •Blood is a fluid connective tissue composed of plasma (about 55% of volume) and formed elements — erythrocytes, leukocytes, and platelets — suspended within it.
  • •Erythrocytes carry oxygen via hemoglobin, a tetrameric iron-containing protein that binds O₂ in the lungs and releases it in peripheral tissues.
  • •Leukocytes are divided into granulocytes (neutrophils, eosinophils, basophils) and agranulocytes (lymphocytes, monocytes), each with distinct roles in innate and adaptive immunity.
  • •Platelets are anucleate cell fragments derived from megakaryocytes that initiate hemostasis by forming a primary plug at sites of vascular injury.
  • •Plasma transports dissolved gases, nutrients, hormones, waste products, and clotting proteins; albumin, the most abundant plasma protein, regulates oncotic pressure and serves as a carrier molecule.
  • •Blood maintains homeostasis by distributing heat, buffering pH through bicarbonate and plasma proteins, and delivering regulatory molecules throughout the body.
  • •The hematocrit — the percentage of blood volume occupied by erythrocytes — averages 42–47% in males and 37–42% in females and serves as a clinical indicator of conditions such as anemia and polycythemia.

Physical Properties and Gross Composition of Blood

Blood is classified as a fluid connective tissue, meaning it consists of living cells and cell fragments dispersed in a non-living extracellular matrix called plasma. Understanding its basic physical characteristics provides the foundation for interpreting every function it performs.

Basic Physical Characteristics

  • •Blood is slightly alkaline, with a normal pH range of 7.35–7.45; even small deviations cause acidosis or alkalosis.
  • •Whole blood has a viscosity approximately 4–5 times greater than water, largely due to the high concentration of erythrocytes and plasma proteins.
  • •Blood temperature runs slightly higher than core body temperature (~38°C) because metabolically active tissues continuously release heat into the bloodstream.
  • •Total blood volume averages 4–6 liters in adults, representing roughly 7–8% of total body weight.

Plasma vs. Formed Elements

  • •Plasma constitutes approximately 55% of blood volume and is about 92% water by weight, with the remainder being dissolved proteins, electrolytes, nutrients, hormones, and waste molecules.
  • •Formed elements — erythrocytes, leukocytes, and platelets — make up the remaining 45% and are produced through hematopoiesis in red bone marrow.
  • •The hematocrit measures the proportion of whole blood volume occupied by packed erythrocytes; values outside the normal range signal conditions such as anemia (low hematocrit) or polycythemia (elevated hematocrit).
  • •Serum is the fluid that remains after blood clots and the formed elements are removed; it differs from plasma in that it lacks clotting factors such as fibrinogen.

Plasma: Composition and Roles

Plasma is far more than a passive solvent — it is an active medium that transports materials, maintains osmotic balance, and provides the molecular tools required for clotting and immune defense.

Plasma Proteins and Their Functions

  • •Albumin, synthesized by the liver, is the most abundant plasma protein (~60% of total) and maintains colloid osmotic (oncotic) pressure, preventing excessive fluid loss from capillaries into interstitial spaces.
  • •Globulins include alpha and beta globulins, which transport lipids, fat-soluble vitamins, and metal ions, and gamma globulins (immunoglobulins), which function as antibodies in adaptive immunity.
  • •Fibrinogen is a soluble plasma protein that is enzymatically converted to insoluble fibrin threads during coagulation, forming the structural scaffold of a blood clot.
  • •Complement proteins, also found in plasma, are part of the innate immune system and can lyse pathogens directly or mark them for phagocytosis.

Dissolved Non-Protein Solutes in Plasma

  • •Electrolytes — principally sodium, potassium, calcium, chloride, and bicarbonate — establish the electrochemical gradients essential for nerve impulse transmission and muscle contraction.
  • •Glucose, amino acids, fatty acids, and vitamins circulate in plasma as substrates delivered to metabolizing cells throughout the body.
  • •Carbon dioxide is transported primarily as bicarbonate ions (HCO₃⁻) dissolved in plasma, making plasma a central component of the body's carbonic acid–bicarbonate buffer system.
  • •Nitrogenous wastes including urea and creatinine dissolve in plasma and are delivered to the kidneys for excretion.

About this Study Pack

Created by Kibin to help students review key concepts, prepare for exams, and study more effectively. This Study Pack was checked for accuracy and curriculum alignment using authoritative educational sources. See sources below.

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