Study guides › B/B › Biology
Immune & Lymphatic Systems
The immune system finds and destroys threats, and the lymphatic system carries its cells and returns fluid to the blood. You will learn innate versus adaptive defense, antibody structure, MHC, T and B cell activation, vaccines, hypersensitivity, and autoimmunity.
Study this chapter in PrepMed (free)
What this chapter covers
- Innate Immunity & Cells of the Immune System. The innate system acts within minutes and is the same every time. Expect questions on which cell does what.
- Antibodies. Antibody structure is a favorite MCAT diagram. Know which part binds antigen, which part signals, and which class does what.
- MHC & T Cells. T cells only see antigen displayed on MHC. Knowing MHC I versus II sorts out most T-cell questions.
- B Cells, Clonal Selection & Vaccines. Primary versus secondary response graphs and active versus passive immunity appear again and again.
- Hypersensitivity, Autoimmunity & the Lymphatic System. The four hypersensitivity types and the route of lymph are reliable exam topics. Learn each with an example.
Key points to know
- Innate: fast, nonspecific, no memory; adaptive: slow first time, specific, memory
- Neutrophils are the first and most numerous responders
- Two heavy + two light chains; variable tips bind antigen
- Fc region binds phagocytes and complement
- MHC I on all nucleated cells presents to CD8; MHC II on APCs presents to CD4
- Helper T cells coordinate both humoral and cell-mediated responses
- Plasma cells secrete antibody; memory cells give the fast secondary response
- Clonal selection: antigen picks pre-existing specific clones and expands them
Try a practice question
Which cell is the most abundant circulating leukocyte and the first to arrive in large numbers at a site of bacterial infection?
- Macrophage
- Neutrophil
- Eosinophil
- Basophil
Show the answer
B. Neutrophils are the most abundant white cells and are recruited first. Macrophages arrive later as monocytes mature in tissue, and eosinophils and basophils mainly handle parasites and allergy.
Common questions
What does this chapter cover?
Immune & Lymphatic Systems covers Innate Immunity & Cells of the Immune System, Antibodies, MHC & T Cells, B Cells, Clonal Selection & Vaccines, Hypersensitivity, Autoimmunity & the Lymphatic System.
What should I know first?
Innate: fast, nonspecific, no memory; adaptive: slow first time, specific, memory Neutrophils are the first and most numerous responders Two heavy + two light chains; variable tips bind antigen
24 original practice questions accompany this chapter in the app. Spaced review brings missed ideas back at the right time; it helps memory but cannot promise you will not miss an idea again.