MCAT Immune System

Woman blowing her nose, representing MCAT immune system - image by Magoosh

Want greater familiarity with the MCAT immune system content you’ll encounter on testing day? We’ll cover everything you’ll want to study for an in-depth understanding of the human immune system.

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Let’s dive in! So first and foremost, the immune system consists of two parts: the innate immune system and the adaptive immune system. We’ll cover each in depth below.

Innate Immune System

  • Non-specific, immediate
  • Components include: antimicrobials, phagocytes, cilia-lined passages, and interferons
  • Active inflammatory response
  • Recruitment of immune cells via release of cytokines

Cells of Innate Immune System

  • Macrophages
  • Mast cells
  • Granulocytes
  • Dendritic cells
  • Natural killer cells

Blood Cell Formation

Blood cell formation, also called hematopoiesis, can be illustrated as follows:

MCAT immunity questions: a complete diagram of blood cell formation - image by Magoosh

Immune Cells (White Blood Cells, Leukocytes)

There are two central categories of immune cells:

GranulocytesAgranulocytes
Neutrophils - phagocytesLymphocytes (B and T cells)
Eosinophils - parasitic killerMonocytes (young macrophages, engulf invaders)
Basophils - histamine release

Adaptive Immune System

  • Specific
  • Activated B-cells produce antibodies in response to pathogens (humoral immunity)
  • Antibodies bind to antigens of pathogen (for example, bacteria)
  • T-cells recognize antigen and signal for apoptosis (cell-mediated immunity)

Cells of Adaptive Immune System

a diagram of adaptive immune system cells, including B-cells and T-cells with examples and an explanation of function. Image by Magoosh.

Major Organs and Tissues

1. Skin

2. Lymphatic System

  • Bone marrow: produces all WBC’s, B-cell differentiation
  • Spleen: blood storage, B-cell activation
  • Thymus: T-cell differentiation
  • Lymph nodes: provide sites for cell communication and attack, B-cell activation

3. Gut-associated lymphoid tissue (GALT)

  • Tonsils and adenoids: trap bacteria and viruses
  • Peyer’s Patches: monitors intestinal bacteria population
  • Appendix: creation/protection of good bacteria

MCAT Immune System Questions: A Final Word

The human immune system is highly complex and a deep understanding of how it works will help you immensely on the Bio/Biochem section of the MCAT. We suggest studying the innate immune system and adaptive immune system separately, as well as in relation to one another.

And as always, studying effectively goes beyond just memorizing the parts of the immune system. Instead, focus on how all of the interrelated parts work together to keep the human body healthy!

For more MCAT practice, hop on over to Magoosh’s MCAT prep, including 745+ practice questions, 380 lessons, and personalized email assistance.

Happy studying and good luck!

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