Blood and Immune System Lecture Review

Question-and-answer flashcards covering lymphatic system functions, innate and adaptive immunity, blood composition, haemostasis, and blood typing, designed for efficient exam review.

What are the three primary functions of the lymphatic system?

To drain interstitial fluid, transport dietary fats, and carry out immune responses.

Trace the flow of lymph from the tissues back to the bloodstream.

Interstitial fluid → lymphatic capillaries → lymphatic vessels → lymphatic trunks → lymphatic ducts → subclavian veins.

Which major cell types are found in the lymphatic system?

T lymphocytes (CD4+ helper and CD8+ cytotoxic), B lymphocytes, natural killer (NK) cells, and antigen-presenting cells such as dendritic cells and macrophages.

Name the primary lymphatic organs and state their roles.

Red bone marrow – produces all lymphocytes; Thymus – site of T-cell maturation and selection.

Give three examples of secondary lymphatic organs or tissues.

Lymph nodes, spleen, and mucosa-associated lymphoid tissue (e.g., tonsils, Peyer’s patches).

What are the two major lines of innate immunity and their main components?

First line: physical and chemical barriers such as skin and mucous membranes; Second line: internal defences including NK cells, phagocytes, inflammation, fever, and antimicrobial proteins.

What four cardinal signs characterise inflammation?

Redness, heat, swelling, and pain.

Outline the three major stages of the inflammatory response.

1) Vasodilation and increased capillary permeability, 2) migration and phagocytosis of phagocytes, 3) tissue repair.

How do natural killer (NK) cells contribute to innate immunity?

They kill virus-infected and tumour cells by releasing perforin and granzymes that induce apoptosis.

Distinguish between antibody-mediated and cell-mediated adaptive immunity.

Antibody-mediated immunity involves B cells differentiating into plasma cells that secrete antibodies; cell-mediated immunity involves T cells that directly attack infected or abnormal cells.

Which immunoglobulin is most abundant in body secretions and what is its primary role?

IgA; it protects mucosal surfaces by neutralising pathogens in saliva, tears, breast milk, and other secretions.

Which immunoglobulin is produced first during a primary immune response?

IgM.

Which class of immunoglobulin mediates allergic reactions?

IgE.

What class of MHC presents exogenous antigens and which T cell recognises it?

MHC class II on antigen-presenting cells; recognised by CD4+ helper T cells.

What class of MHC presents endogenous antigens and which T cell recognises it?

MHC class I on all nucleated cells; recognised by CD8+ cytotoxic T cells.

Why is the secondary immune response stronger than the primary response?

Memory B and T cells generated during the primary response enable faster, stronger antibody and cytotoxic responses upon re-exposure to the same antigen.

Which cells are targeted and destroyed by HIV?

CD4+ helper T lymphocytes.

What is autoimmunity?

A condition in which the immune system fails to recognise self-antigens and attacks the body’s own tissues.

Describe the general effect of ageing on immune function.

Immune responses decline with age owing to reduced production of naïve B and T cells and diminished responsiveness to antigens.

What percentage of blood volume is plasma, and what are its major components?

About 55%; plasma is ~90% water plus proteins (albumin, globulins, fibrinogen), nutrients, hormones, gases, and wastes.

Approximately how many red blood cells are found in one microlitre of blood?

Roughly 5 million red blood cells per microlitre.

How long does a typical erythrocyte live, and what hormone regulates its production?

Approximately 120 days; erythropoietin (EPO) secreted by the kidneys stimulates RBC production.

Differentiate between granular and agranular leukocytes, giving examples.

Granular leukocytes: neutrophils, eosinophils, basophils; Agranular leukocytes: lymphocytes and monocytes.

What is the average lifespan and primary function of platelets?

5–9 days; they are cell fragments that form platelet plugs and release factors essential for blood clotting.

List the three phases of haemostasis.

Vascular spasm, platelet plug formation, and coagulation (blood clotting).

Which vitamin is required for the synthesis of several clotting factors?

Vitamin K.

What enzyme dissolves a formed blood clot?

Plasmin.

Identify the antigens present on type AB blood and the antibodies present in its plasma.

Type AB blood has both A and B antigens on its red blood cells and has neither anti-A nor anti-B antibodies in its plasma.

What determines Rh positivity, and why is it clinically important in pregnancy?

Presence of the D antigen on red blood cells confers Rh positivity; maternal–fetal Rh incompatibility can cause haemolytic disease of the newborn if an Rh- mother carries an Rh+ fetus.

Define haematocrit (PCV).

The percentage of whole blood volume occupied by red blood cells; also called packed cell volume.

What is diapedesis and why is it important?

The process by which white blood cells squeeze through capillary walls to exit the bloodstream and reach sites of tissue infection or injury.