A+P: Lymphatic System

Lymphatic System

Consists of lymphatic vessels and lymphoid tissues+organs

Lymphatic Vessels

Drainage system returning excess fluid (lymph) to the blood

Lymph

Moves in one-way (towards the heart) with the help of muscle contractions, excess fluid in lymphatic vessels

Lymph Nodes

Lymph is filtered through these and removes foreign like bacteria or tumor cells as it passes through, found in inguinal (genitals), axillary (armpit), and cervical (neck) regions, macrophages and lymphocytes are found here

Macrophages

Found in lymph nodes, engulf+destroy bacteria, viruses, etc.

Lymphocytes

Found in lymph nodes, respond to foreign substances in the lymphatic system

Lymphoid Organs

Spleen, Thymus, Peyer’s Patches,

Spleen

Filters and cleans blood of bacteria, viruses, and debris, destroys worn out red blood cells and returns breakdown products to liver, lymphoid organ

Thymus

Produces hormones that program lymphocytes to carry out their protective functions, lymphoid organ

Peyer’s Patches

Capture+destroy bacteria from penetrating intestinal wall, lymphoid organ

Two Defense Systems

Innate Defense System (Non-specific Defense System) and Adaptive Defense System (Specific Defense System)

Innate Defense System (Non-specific Defense System)

Responds immediately to protect the body from all foreign substances - our body comes full equipped with this system

Adaptive Defense System (Specific Defense System)

Mounts attacks against particular foreign substances - system must be developed after pathogen exposure

First Line of Defense (Innate)

Skin (keratinized epidermis as strong physical barrier)+Mucous Membranes (provide similar protection, lines all body cavities open to exterior)

First Line of Defense (Innate Secretion)

Secretion of Skin/Mucous Membranes, skin acidity (pH 3-5) inhibits bacterial growth, sebum contains chemicals toxic to bacteria, HCl and protein-digesting enzymes in stomach kill pathogens, saliva+lacrimal fluid contains lysozyme that destroy bacteria, mucus traps microorganisms that enter digestive/respiratory tract

Second Line of Defense (Innate)

Internal defenses, phagocytes, natural killer (NK) cells, inflammatory response, antimicrobial proteins, fever, metabolic rate of tissue cells increase →speed up repair of cells

Phagocytes

Engulf foreign particles and breaks them down (ex. macrophage or neutrophil), apart of innate second line of defense

Natural Killer (NK) Cells

Police body in blood/lymph, lymphocyte that can spontaneously lyse/kill (burst) any pathogen, releases perforin (lyric chemical) apart of innate second line of defense

Inflammatory Response

Triggered whenever body tissues are injured, release inflammatory chemicals (histamine/kinins) calling phagocytes and white blood cells to the area, common signs (redness, heat, swelling, pain), apart of innate second line of defense

Antimicrobial Proteins

Attack microorganisms directly or hinder their ability to reproduce, complements and interferons, apart of innate second line of defense

Complement

Antimicrobial protein, attach to foreign cells to help fight them

Interferon

Antimicrobial protein, interfere with ability of viruses to multiply

Fever

Mild/moderate can benefit body bacteria need large amounts iron/zinc liver/spleen gather these up during fevers, apart of innate second line of defense

Third Line of Defense (Adaptive)

Specific Defense System that recognizes antigens and either inactivates or destroys them, antigens and antibodies

Antigen

Foreign molecule (which induces immune response)

Antibodies

Proteins that protect the body against future attack

Adaptive Body Defenses

Antigen specific, systemic, memory

Antigen Specific

Recognizes and acts against particular pathogens and foreign substances (Adaptive)

Systemic

Immunity is not restricted to the initial infection site (Adaptive)

Memory

Recognizes and mounts even stronger attacks on previously encountere