Composition and Function of Blood – Lecture Review

A set of question-and-answer flashcards covering major concepts from the blood composition lecture, including plasma, formed elements, WBC types, blood typing, hematocrit, coagulation, and hemoglobin.

What percentage of a typical blood sample is plasma versus formed elements?

About 55 % plasma and 45 % formed elements.

What are the principal components of plasma by percentage?

92 % water, 7 % plasma proteins, and 1 % other solutes.

State one main function of blood plasma.

It transports organic and inorganic molecules, formed elements, and heat throughout the body.

List the three categories of formed elements and their relative proportions in whole blood.

Red blood cells (~99.9 %), white blood cells (<0.1 %), and platelets (<0.1 %).

Which blood cells lack a nucleus and what is their primary function?

Red blood cells (erythrocytes); they transport O₂ and CO₂ via hemoglobin.

Why does the biconcave shape of an RBC enhance its function?

It provides more surface area than a flat disc, facilitating efficient gas exchange.

What are leukocytes and how do they differ from erythrocytes?

Leukocytes (white blood cells) contain nuclei, lack hemoglobin, and can leave blood vessels to enter tissues; they do not transport gases.

Name the two major classes of white blood cells.

Granular leukocytes (granulocytes) and agranular leukocytes.

What are granular leukocytes (granulocytes)?

Granular leukocytes, also known as granulocytes, are white blood cells that contain prominent cytoplasmic granules. This class includes neutrophils, eosinophils, and basophils.

What are agranular leukocytes?

Agranular leukocytes are white blood cells that lack obvious cytoplasmic granules. This class includes lymphocytes and monocytes.

Which WBCs are most abundant and what is their role at a wound site?

Neutrophils (50–70 % of WBCs); they are the first responders for infection control.

What is the typical percentage and primary job of eosinophils?

2–4 %; they engulf bacteria or parasites coated with antibodies.

Basophils make up less than 1 % of WBCs. What substance do they release at injury sites?

Histamines.

Describe the role and percentage range of monocytes.

2–8 %; they arrive after neutrophils and phagocytize pathogens and dead neutrophils.

What are lymphocytes, and what are the two key subtypes?

They are 20–30 % of WBCs and provide immunity. Subtypes: T-cells (destroy foreign cells) and B-cells (produce antibodies).

How many ABO blood types exist and what determines them?

Four (A, B, AB, O); determined by the presence or absence of A and B surface antigens on RBCs.

Which plasma antibodies are found in each ABO blood type?

Type A: anti-B; Type B: anti-A; Type AB: neither anti-A nor anti-B; Type O: both anti-A and anti-B.

What factor distinguishes Rh⁺ blood from Rh⁻ blood?

Rh⁺ blood has the D (Rh) surface antigen and no anti-D antibodies; Rh⁻ blood lacks the antigen and initially lacks anti-D antibodies.

What immune reaction occurs if an Rh⁻ individual is exposed to Rh⁺ blood?

The Rh⁻ person becomes sensitized and starts producing anti-D antibodies.

What does the hematocrit test measure and what are normal ranges?

It measures the volume percentage of packed red cells; males 40–54 %, females 37–47 %.

Define coagulation in blood and name the key insoluble protein formed.

It is the process where liquid blood forms a gel; fibrinogen is converted into insoluble fibrin, which creates a mesh to plug wounds.

Outline the structure of a hemoglobin molecule.

Each Hb has two alpha and two beta chains; each chain contains a heme group with an iron ion that binds O₂ or CO₂.

• Active Immunity:

  
  

• Occurs when an individual's own immune system produces antibodies and memory cells in response to direct exposure to an antigen (e.g., natural infection or vaccination).

• Provides long-lasting protection because the body remembers the pathogen.

• 
  

• Passive Immunity:

• Occurs when an individual receives pre-formed antibodies from another source (e.g., mother to fetus via placenta, anti-venom).

• Provides immediate but temporary protection because the body does not create its own memory cells or antibodies.

• Adaptive (Specific) Immunity:

• 
  

  • A highly specific type of immunity that develops throughout an individual's life in response to exposure to specific pathogens or antigens.

  • Involves specialized cells: T and B cells

Vascular Phase

Immediate phase where vessel diameter decreases due to smooth-muscle contraction (vascular spasm) and endothelial cells release factors like ADP, tissue factor, and endothelins, making membranes sticky to seal micro-tears.

It plays a crucial role in hemostasis by reducing blood flow and initiating the clotting process.

Platelet Phase

Starts around 15 seconds after injury; involves platelet adhesion to exposed collagen/basement membrane and platelet aggregation to form a temporary platelet plug. Activated platelets also secrete factors like ADP, thromboxane A2, and serotonin.

It follows the vascular phase, where platelets adhere to the site of injury and release chemicals that promote further platelet recruitment and activation, contributing to the clotting process.

Coagulation Phase

tarts around 30 seconds after injury; a cascade involving 11 plasma proteins, calcium ions (Ca2+Ca2+), and vitamin K-dependent synthesis, leading to the conversion of fibrinogen to insoluble fibrin strands that form the clot's framework.

The coagulation phase is critical in stabilizing the platelet plug