A&P Final

Lymphatic system

Provides alternate method for fluid in interstitial spaces to return blood

• Can also carry substances that are too large to re-enter the capillaries

Lymphatic capillaries

• formed by epithelial cells with loose junctions

• overlap to form a kind of valve

  • only lets fluid flow in one direction

  • movement between cells=pericellular

Four types of defense barriers (innate immunity)

• Anatomic

• Physiologic

• Endocytic and phagocytic

• Inflammatory

Anatomic barriers

• skin and surface of mucous membranes

• first line of defense (barrier for entry)

• dermis secretes sebum (pH 3-5)

  • provides an unfavorable environment for microbial growth

• Surface of mucous membranes:

  • conjunctivae and alimentary, respiratory, and urogenital tracts provides tears, saliva, and mucus secretions

  • wash away and entrap (mucus) microorganisms

Physiologic Barrier

• Body temperature: temperature achieved with fever and basal body temperature in some animals does not favor microbial survival

• Gastric acidity

• soluble proteins

  • Lysozyme- found in mucous secretions; hydrolyze bacterial cell walls.

Endocytic and phagocytic barrier

Endocytosis-

• Large molecules in extracellular tissue fluid may be internalized by cells

• Internalization occurs as small regions of the plasma membrane invaginate and form small endocytic vesicles

Endocytic mechanism

• The folding inward of the cells plasma membrane forms endocytic vesicles

• several endocytic vesicles fuse to form endosomes

  • Internal environment is acidic

• Endosomes fuse with primary lysosomes to form secondary lysosomes

  • Primary lysosomes contain degradative enzymes

  • Macromolecules are degraded within secondary lysosomes

Phagocytosis

• Differs slightly from endocytosis

  • plasma membrane expands around the cell or particular matter to form phagosomes

  • Only specialized cells participate with lysosomes and processing of phagocytized materials proceeds much as in endocytosis

Inflammatory Barriers

• Series of events that lead to:

  • increased blood flow to area

    • local capillary engorgement and redness increased temperature

  • Increased capillary permeability

    • fluid and cells move into tissue (swelling)

  • Influx of phagocytic cells

    • clear invading organisms (antigens)

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Atrial Fibrillation

Uncoordinated spread of the electrical impulses through the atrium.

• Not usually fatal on its own

• Slight loss of blood being pumped but the ventricles normally pump 75% of the blood on their own, so there is already quite a lot of blood pumping capacity using only the ventricles.

AV node

Bundle of cells within the right atrium that receives the action potential generated by the SA node via internodal and transitional fibers. The AV node is naturally leaky to sodium but less leaky than the SA node. As a result, the SA node is the natural pacemaker, but the AV node can take over if necessary.

Bundle of His

Large, conductive cardiac cells that carry the action potential from the AV node into the ventricular septum and then to Purkinjie fibers

Congestive Heart Failure (CHF)

General name for the condition where the heart is unable to pump all the blood that is coming into it. In some cases, CHF is on the right side and is usually due either to a leaking tricuspid or pulmonary valve, a restricted ability to fill due to swelling within the pericardium, or restriction on blood flowing to the lungs through the pulmonary artery.

Left side CHF is most often due to hardening and/or narrowing of the aortic opening.

Diastole

Period where the ventricles relax and fill with blood. This produces the low number in a blood pressure reading as the elastic arteries constrict the blood and keep pressure from falling too far while the ventricles are relaxing.

Internodal Fibers

Fibers within the right atrium that conduct the action potential from the SA node to the AV node, also in the right atrium. The internodal fibers connect to transitional fibers that are very small and inefficient at conducting the AP, and this the AP reaches the AV node about 1/10th of a second after it is generated in the SA node.

Pathogen

disease causing molecule(virus) or organism

Antigen

portion of the pathogen that our immune system recognizes

Why do lymph nodes swell?

Bacteria

What human body systems is the lymphatic system a part of?

Circulatory AND immune systems

Phagocytosis

requires a mobile cell, engulfs pathogens or other particles. large size

Endocytosis

cell that is fixed in tissue, engulfs pathogens or particles. EX: dendritic cells

How are viruses brought into the cell and replicated?

spike proteins on the outside of the virus bind to receptors on the cell causing the virus to be brought into the cell. Then the mRNA is replicated.

How does a phagocyte destroy viruses?

• Takes up virus

• breaks up all proteins

• analyzes and identifies the antigen

• shows antigen to Helper t-cells

• Neutralizes spike proteins preventing cells from taking up virus and duplication RNA

This allows body to build acquired immunity

Memory b-cells

go to the lymph nodes or bone marrow and wait until net exposure

Natural immunity from exposure to a virus

• antibody binds to spike protein

• prevents uptake and replication of virus

• keeps # of pathogens low enough that you won’t get the disease

Antiviral Vaccine

• mRNA that encodes antigen on the spike protein is injected into an animal

• dendritic cell takes up mRNA and makes antigen

• dendritic cell shows the antigen to the T-cells

• T-cells tell the B-cells to produce antibodies

• B-cells create memory and plasma cells