Lesson 7 - IgG said ,"Here are the rest of my friends ..."

Immunoglobulins or Antibodies:
    IgA: They are found in mucosal areas such as the urogenital tract, gut, and respiratory tract. They are also found in tears, saliva, and breast milk. They attack microbes and prevent colonization by pathogens before they reach the blood stream.
    IgD: They are found on inactivated B-cells. They also activate basophils and mast cells which produce antimicrobial factors.
    IgG: They are the most common and make up about 75% of all antibodies. They are the only one to be able to cross the placenta to the fetus. They are the most versatile.
    IgE: They bind to allergens which causes the release of histamine from mast cells and basophils. They are mainly involved in allergies.
    IgM: They are first to eliminate the pathogen before IgG arrives. They are expressed on the surface of B-cells.

Major Organ:
    Thymus: It is the site of T-cell maturation. It is located in the upper area of the chest behind the sternum and between the lungs. It is pinkish-grey.
    There are other organs that you will learn about in the next couple of lessons.

Lesson 6 - ANTIBODY THREAT: I'm gonna AGGLUTINIZE you!

ATTACK OF THE ANTIBODIES

Adaptive Immunity:
    The adaptive immune system is the part of the immune system that can specifically target pathogens. It also stores immunological memory. This memory means that when a pathogen is encountered a second time, the response will be quicker and more effective. This memory can be stored in different types of B-cells and T-cells. There are two types of adaptive immunity: cellular and humoral.
    B-cells: They are immune cells that mature in the bone marrow. They are involved in humoral immunity. When they encounter an antigen (substances that can cause a adaptive immune response), the cells divide into plasma cells, which produce antibodies and into memory cells which store memory in case of a second exposure.
    T-cells: They are immune cells that mature in the thymus. They are involved in cellular immunity. There are four types. The helper T-cells help activate other T-cells and B-cells. Cytotoxic T-cells kill virally infected cells or cancerous cells. They act like natural killer cells. They also use perforins and granzymes. Memory T-cells have the same function as memory B-cells. They store immunological memory in case of a second exposure. Regulatory or Suppressor T-cells are the cells that stop the immune response. This prevents the immune system from going crazy.
    You may have heard me mention the word antibody. Antibodies are Y-shaped proteins that bind to a specific antigen. They all have a variable portion that is different among every plasma B-cell. This helps the immune system to be more versatile and a more variety of pathogens that they can kill. Antibodies fight infection in four ways: Complement fixation and activation, Agglutination, Neutralization, and Precipitation. Complement fixation and activation helps activate the complement (self explanatory). This means that they help with phagocytosis (adherence specifically). Neutralization occurs when antibodies block specific site on bacteria or viruses which cause them to be inactive. Agglutination occurs when antigens clump together which also makes adherence easier for phagocytes. Precipitation is the same as agglutination, but with free-floating antigens not with cells.

Lesson 5 - The Macrophage said ,"I DON"T KNOW YOU, SO I WILL EAT YOU!!!!!!"

DEATH SENTENCE: PHAGOCYTOSIS

Innate Immunity:
    The immune system is the body system that fights infection and keeps our body from pathogens. There are types of immunity: Innate and Adaptive Immunities.
   Innate Immunity: The innate immune system is the cells and physical barriers that you are born with. They target all types of pathogens; not specific pathogens.  The innate immune system consists of two lines.
    The 1st line consists of physical barriers including skin, nose, stomach, and other mucosae. Keratin on the skin makes the skin resistant to bacteria. Secretions such as sebum and sweat make the skin slightly acidic. The stomach contains gastric juice which destroy pathogens in the stomach. Tears and saliva contain lysozymes which kill pathogens in the oral cavity (mouth) and eyes.
    The 2nd line consists of phagocytes (cells that engulf pathogens), natural killer cells (cells that kill our own body cells that are cancerous or virally infected), antimicrobial proteins, and causes fever and inflammation. Phagocytes engulf pathogens through phagocytosis. Phagocytosis has 5 steps: Adherence-occurs when the phagocyte binds to the pathogen. Endocytosis-the cell membrane reaches around pathogen to enclose which forms a phagosome or food vacuole. Fusion-lysosome fuses with the phagosome. Digestion-the lysozymes from the lysosomes digest and breakdown the pathogen. Exocytosis-the unneeded material is ejected from the cell. Opsonization occurs when complement proteins or antibodies bind to the pathogen and makes adherence easier. Respiratory Bursts occurs when the lysosome is not enough so the T-cells release free radicals.

Natural Killer cells kill out own human cells that have already been infected or have become cancerous. They function using perforins and granzymes. The perforins create a hole in cell membrane and the granzymes enter and breakdown cell material.

Lesson 4 - Skin Diseases

You DO NOT want to get these in your body!!!!!

Diseases of the Integumentary:
    Cancers:
        Malignant Melanoma: It is a cancer that develops in the melanocytes (from lesson 2). It is can be caused by tanning beds and ultraviolet light overexposure. It is the most dangerous of skin cancers. It easily metastasizes through dermal blood vessels. They are normally black or dark brown in color.
        Basal Cell Carcinoma: It is a cancer that develops in the stratum basale. It is the least dangerous of all cancers. It rarely metastasizes. It is generally raised off the skin in bumps. It is the most common skin cancer.
        Squamous Cell Carcinoma: It is a cancer that develops in the squamous cell. It mainly affects the epidermis. It causes scars and bumps with a central depression.

    Other Diseases:
        Psoriasis: It is a chronic skin disease that is characterized by silvery, white inflamed lesions. It is caused by overactive T-cells collecting in the skin. It can be treated with small doses of sunlight, salicylic acid, and prescription retinoids.
        Vitiligo: It is a disease that causes the depigmentation of the skin. It occurs when pigment cells die or malfunction.
        Ringworm: It is a fungal infection caused by dermophytes that feed on keratin. These dermophytes thrive in warm and moist conditions. They can be treated with gold bond, different prescription creams, and drier feet.

ABCDE: A rule to determine a skin cancer. A-Asymmetry, B-Border, C-Color, D-Diameter, E-Evolution


There are still other diseases that you need to learn.

Lesson 3 - OMG! I need to brush my hair!

STUFF ABOUT YOUR HAIR!!

Hair Information:
   
    Hair Cross-sectional Anatomy:
        The 3 main layers of the include: medulla to the cortex to the cuticle. They are all made from hard keratin
    Medulla: It is the innermost layer. It is present in different amounts in different hairs (not consistent).
    Cortex: It is the middle layer. It contains pigment and gives the hair its color. It may  contain ovoid bodies and cortical fusi.
    Cuticle: It is the outermost layer. It is made from overlapping scales. It is very resistant to chemical decomposition.
   
    Hair General Anatomy:
        The hair above the surface of the skin is known as the hair shaft. The hair below the surface of the skin is known as the hair root. The hair under the skin is located in a hair follicle which houses the hair root. The arrector pili muscle is attached to the hair follicle. It contracts when you are in fear or when you are cold.

    Hair Phases:
        Anagen: Anagen is the growth phase for the hair. Hair can last in Anagen for 2-7 years.
        Catagen: Catagen is the transitional phase for the hair. It is a 2-3 week phase. It lasts until the hair becomes a club hair. A club is formed when the hair is pushed toward the surface of the skin until it is cut off from the blood supply and hair matrix (site of hair growth).
        Telogen: Telogen is the resting phase for the hair (which is a club hair just in case you forgot from about 3 lines ago). 50-100 club hairs are shed from a normal scalp.

    Affect of Age on the Hair:
        When hair turns white, it is because of decreased melanin production and air bubbles produced in the medulla of the hair.

Lesson 2 - SWEATING? TOUCHING?

HOW DO WE SWEAT??? WHAT DO WE DO TO SWEAT??   


Mechanoreceptors and Glands:

The four mechanoreceptors of the Integumentary System include: Merkel cells, Pacinian corpuscles, Meissner's corpuscles, and Ruffini corpuscles.
   Merkel cells: They are sensory receptors for touch. It lies on the Merkel disc. It lies at the epithelial-dermal junction.
    Pacinian Corpuscles: They are nerve endings that are sense vibration and pressure. It is very few in number and is 1mm in length. They can sense up to 250Hz.
    Meissner's Corpuscles: They are nerve endings that sense light touch. They can sense well between 10Hz and 50Hz.
    Ruffini corpuscles: It is found in the subcutaneous layer. It helps sense warmth. It is also known as Bulbous corpuscle.

Exocrine glands are glands that secrete out onto the environment directly.
Sudoriferous glands are sweat glands. There are two types: Apocrine and Eccrine glands.
    Apocrine glands: They are a type of sudoriferous gland. They are located at the junction between the subcutaneous layer and dermis. They are only located at the armpits, areola and nipples of breasts, and genital area. Their secretions have a odor.
    Eccrine glands: They are a type of sudoriferous gland. They secrete directly onto the skin. Their secretions are odorless.
Sebaceous glands are glands that secrete sebum. The secrete directly on the hair. Sebum inhibits bacterial growth on the skin.

Lesson 1 - WHAT IN THE WORLD IS THE SKIN?????

    WHAT IS THE SKIN??????????????
    The Integumentary System consists of the skin and its accessories. It is the largest organ system in the human body. Its main function is to act like a barrier to protect the body from the outside world. It also retains body fluids, eliminate waste, protect against disease, and regulate body temperature.
    The Integumentary System has two layers: epidermis and dermis. The epidermis is the most superficial. It consists of 5 layers: stratum corneum, stratum lucidum, stratum granulosum, stratum, spinosum, and stratum basale. This is only in thick skin which is found only on palms and the soles of your feet. In thin skin, the stratum lucidum is not present. The stratum basale is the site of mitosis. The blood supply to the epidermis is the subpapillary plexus.
    The dermis is located right under the epidermis. It has two layers: papillary and reticular. The papillary layer is more superficial. It contains areolar tissue. The reticular layer contains connective tissue. The blood supply to the dermis is the cutaneous plexus (cutaneous meaning skin).
    The hypodermis is not considered part of the skin. It is made up of areolar tissue and adipose (fat) tissue. It is known as the subcutaneous layer (below the skin). It acts as a energy reserve for the skin.





This diagram is very important to learn. It can help to memorize it.
Lesson 1 End