AP Biology Notes: Immune and Endocrine Systems

Four Things to Know about Immune Systems

  1. The immune system can be divided into two major divisions: nonspecific (targets general infections) and specific (attacks specific disease-causing organisms by protein-to-protein interaction). Specific immunity is how we become immune to future infections from pathogens we have already fought off.
  2. Specialized white blood cells, lymphocytes, come in two varieties: B cells and T cells. They are produced by stem cells in the bone marrow. There are three types of T cells: helper (TH), cytotoxic (TC), and suppressor (TS).
  3. There are five types of antibodies and their structures are based on the same four polypeptide chains.
  4. Antibodies work through agglutination/neutralization, precipitation, and complement activation.

Five Things to Know about Endocrine Systems

  1. There are two major ways animal cells communicate: through signaling molecules secreted by cells and through molecules that rest on the cell surface. Signaling molecules can be further divided into paracrine, synaptic, and endocrine.
  2. Some cell communication occurs through cell junctions and is important for complex tissues to be able to function properly. There are three major types of cell junctions: tight junctions, desmosomes, and gap junctions.
  3. The endocrine system works with the nervous system to produce certain reactions as needed in response to changes in the body’s organ systems.
  4. Hormones are one of the body’s methods of internal communication. Hormones are secreted by endocrine glands and travel throughout the body. They activate receptor cells that produce receptor proteins, thereby creating a reaction.
  5. There are two major types of hormones: steroid hormones and nonsteroid hormones. Nonsteroid hormones are usually made up of proteins or modified amino acids.

Key Topics–Immune and Endocrine Systems

Remember that the AP Biology exam tests you on the depth of your knowledge, not just your ability to recall facts. While we have provided brief definitions here, you will need to know these terms in even more depth for the AP Biology exam.

Immune Systems: Nonspecific Defenses

  • Antigen: A foreign protein that stimulates the production of antibodies when introduced into the body of an organism

Immune Systems: Specific Defenses

  • Lymphocyte: A kind of white blood cell in vertebrates that is characterized by a rounded nucleus; involved in the immune response
  • Antibody: Globular proteins produced by tissues that destroy or inactivate antigens
  • Immunity: A resistance to disease developed through the immune system
  • Active immunity: Protective immunity to a disease in which the individual produces antibodies as a result of previous exposure to the antigen

Endocrine Systems: Cell Communication

  • Extracellular matrix: Material found outside of the cell
  • Adrenaline (Epinephrine): An “emergency” hormone stimulated by anger or fear; increases blood pressure and heart rate to supply the emergency needs of the muscles
  • Tissue: A mass of cells that have similar structures and perform similar functions
  • Intestines: Part of the alimentary canal that extends from the stomach to the anus

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