Untitled

graph TD
    A[Four Main Body Membranes] --> B(Mucous Membranes);
    A --> C(Serous Membranes);
    A --> D(Cutaneous Membrane);
    A --> E(Synovial Membranes);

    B --> B1{Location};
    B1 --> B1a(Line cavities open to the exterior);
    B1a --> B1a1(Respiratory, digestive, urinary, and reproductive tracts);
    B --> B2{Composition};
    B2 --> B2a(Epithelial tissue on top of connective tissue);
    B --> B3{Primary Function};
    B3 --> B3a(Secrete mucus for protection and lubrication);

    C --> C1{Location};
    C1 --> C1a(Line internal cavities and cover organs);
    C1a --> C1a1(Pleurae around lungs, pericardium around heart, peritoneum around abdominal organs);
    C --> C2{Composition};
    C2 --> C2a(Simple squamous epithelium supported by connective tissue);
    C --> C3{Primary Function};
    C3 --> C3a(Secrete serous fluid for lubrication and reduce friction);

    D --> D1{Location};
    D1 --> D1a(The skin, which covers the entire external surface of the body);
    D --> D2{Composition};
    D2 --> D2a(Stratified squamous epithelium on top of connective tissue);
    D --> D3{Primary Function};
    D3 --> D3a(Protect the body from desiccation and pathogens);

    E --> E1{Location};
    E1 --> E1a(Line the cavities of movable joints, such as the knee, shoulder, and elbow);
    E --> E2{Composition};
    E2 --> E2a(Connective tissue only);
    E --> E3{Primary Function};
    E3 --> E3a(Produce synovial fluid to lubricate the joints);