Announcements Exams- Extra Credit - Lab 5 - Lymphatic System

Lecture Overview Lymphatic System and Components – What is lymph and how does it travel? General Immune Reaction- Inflammation – What is one function of the cells carried in lymph? Selected Topics in Immunity

Lymphatic System Absorbs excess fluid from the tissues Returns this fluid to the circulatory system or the heart Additional function in Immunity

Components of the Lymphatic System Lymph Lymphatic Tissue Lymphatic Vessels Thymus Bone Marrow Spleen

Lymph Lymph – The clear fluid absorbed by the lymphatic system Lymphatic Tissue – Clusters of Lymphocytes and macrophages

Lymphatic Tissue Malt: ( Mucosa Associated Lymphatic Tissue ) – Diffuse array of lymphocytes found along body passages in mucous membranes. – Examples of malt: lining of the stomach and respiratory tract Lymph nodules: – Dense clusters of Lymphocytes – Transient: pop up during infection

Lymphatic Vessels Carry and Transport Lymph and proteins Similar Structure to veins – Tunica Interna: Thin inner lining and valves – Tunica Media: Elastic fibers and Smooth Muscle – Tunica Externa: Thin Outer Layer

Lymphatic Filters Lymph Nodes- Screen and Filter Lymph for infectious particles Spleen- Screen and Filter Blood for old, dead cells and infectious particles

Subclavian 2 collecting Trunks 6 Lymphatic Trunks More Collecting Vessels Lymph Nodes Collecting Vessels Lymphatic Vessels

Lymphatic Movement No pump Rhythmic contraction of the lymph vessels Skeletal Muscles How is backflow prevented?

Immune Cell Generators Bone Marrow- Makes B- Cells Thymus- Makes T- Cells

Thymus

Break for Dynamic Human

Inflammation Non-specific response to tissue trauma or infection

4 signs of Inflammation

Redness Swelling Heat Pain What’s the purpose of pain?

Purpose of Inflammation Remove Invading Pathogens Remove Debris of Damaged Tissues Initiate Tissue Repair

Mediators of Inflammation Chemical Messengers Leukocyte

Chemical Messengers Released by mast cells in response to damage Bradykinin, Histamine, and Leukotrienes – Increases Local Blood Flow to distressed area Stimulates Vasodilation Increases Permeability of Capillaries What’s Accomplished?

Chemical Messengers Bradykinin, Histamine, and Leukotrienes – Increases Local Blood Flow Stimulates Vasodilation Increases Permeability of Capillaries What’s Accomplished? – Heats area causes redness and swelling – Dilutes toxins and helps Remove waste – Supplies oxygen and nutrients for tissue repair

Pain Response Purpose? Causes?

Pain Response Purpose? Prevents further injury to area. Causes? – Direct Nerve Damage – Pressure from Swelling – Chemical Stimulation particularly bradykinin

Leukocyte Deployment Leukocyte: any white blood cell including T cells, B cells, granulocytes, platelets, basophils, mast cells, monocytes and macrophages Leukocytes Migrate toward inflammed area Why? TO KILL and RECRUIT

Leukocyte Deployment Leukocytes Migrate to inflammed tissue How? 1. Margination or pavementing: To migrate to the wall of a capillary 2. Diapedesis: Passage of blood cells through vessel wall into tissue 3. Chemotaxis: Movement of a cell towards or away a chemical source

What do the leukocytes plan to do? Phagocytosis: release of toxic chemicals Recruit more leukocytes

Phagocytosis Leukocytes consume and destroy foreign invaders and dead cells Ejected as Pus

Break for Dynamic Human

Selected Topics in Immunity