University of Wisconsin-Eau Claire Biology 314: Exam Two Study Material

How many times more bacterial cells does the body have than human cells?

10 Times more

Are all bacteria housed in the body bad?

No, some are beneficial

Is the immune system an organ system?

No, it is a cell population

What is the immune system?

A cell population the inhabits all organs and defends the body from agents of disease.

What area of the body is the immune system most concentrated?

The Lymphatic System

What is the Lymphatic system/what does it do?

It is a network of organs and vein-like vessels that recover fluid

Inspect it for disease agents

Activate immune responses

Returns fluid to the bloodstream

How much water and plasma proteins enters the lymphatic system, and then are returned to the blood (percentage)

15% of water and 50% of plasma proteins

What structure of the lymphatic system absorbs the excess fluid and proteins?

The lymphatic capillaries

How does the lymphatic system aid in immunity?

excess filtered fluid picks up foreign cells and chemicals in the tissues

Passes through lymph nodes where immune cells stand guard against foreign matter

Activates a protective immune response

Describe Lipid Absorption in the lymphatic system

lacteals, in the small intestine absorb dietary lipids that are not absorbed by the blood capillaries.

What is Lymph

The recovered fluid

Clear colorless fluid, like plasma, but much less protein

Chemical composition varies in different places

What are Lymphatic Vessels?

Tube structures that transport the lymph

They penetrate all tissues, excluding cartilage, cornea, bone, and bone marrow

Describe the structure of Lymphatic Capillaries

Capillary wall is endothelial cells overlapping each other like roof shingles.

They are closed at one end.

Cells tethered to surrounding tissues by protein filaments

Endothelium creates valve-like flaps that open when

Interstitial fluid pressure is high, and close when it is low

What are lymphatic tissues?

Tissues composed of aggregates of lymphocytes and macrophages that populate many organs in the body

What are Lymphatic organs?

Organs where the defense cells are especially concentrated

Separated from surrounding organs by connective tissue capsules

What are the 3 layers of large lymphatic vessels?

Tunica Interna: The Endothelium and Valves

Tunica Media: Elastic Fibers, Smooth Muscle

Tunica Externa: Thin Outer Layer

What are the six lymphatic trunks?

They drain major portions of body

What are the two collecting ducts?

Right Lymphatic Duct and Thoracic Duct

What does the right lymphatic duct do?

She receives lymph from the right arm, right side of head and thorax, empties into right subclavian vein.

Describe the Thoracic Duct

it is larger and longer, begins as a prominent sac in abdomen called the cisterna chyli. It receives lymph from below diaphragm, left arm, left side of head, neck and thorax. It empties into the left subclavian vein.

How does Lymph flow through the body/what forces govern flow?

Lymph is moved around by rhythmic contraction of lymphatic vessels.

Skeletal muscle pump, arterial pulsation rhythmically squeezes lymphatic vessels

Valves prevent backwards flow

What can significantly increase lymphatic return?

Exercise

What Natural Killer (NK) cells?

Large lymphocytes that attack and destroy bacteria, transported tissue, host cells infected with viruses or that have turned cancerous

What are T Lymphocytes (T Cells)?

Lymphocytes that mature in the thymus

What are B Lymphocytes (B Cells)?

Lymphocytes that activation cause proliferation and differentiation into plasma cells that produce antibodies

What is a Macrophage and what are its functions?

Macrophages are large, phagocytic cells of connective tissue.

Phagocytize tissue debris, dead neutrophils, bacteria, and other foreign matter. They process foreign matter and display antigenic fragments to certain T cells. Alerting the immune system of the enemy.

What are antigen presenting cells?

Cells that display bits and pieces of what they killed

What are dendritic cells?

These are branched, mobile APC's found in the epidermis, mucous membrane, and lymphatic organs.

They are the early alert system for the immune system

What are reticular cells

Branched stationary cells that contribute to the stroma of a lymphatic organ.

What is Lymphatic (lymphoid) tissue

aggregations of lymphocytes in the connective tissue of mucous membranes and various organs

What is Diffuse Lymphatic Tissue

The simplest form

Scattered lymphocytes

Prevalent in body passages open to the exterior

Respiratory, digestive, urinary, and reproductive tracts.

What are lymphatic Nodules (follicles)

Constant feature of the lymph nodes, tonsils, and appendix Dense masses of lymphocytes and macrophages that congregate in response to pathogens

Are Lymphatic organs well defined anatomically?

Yes, they have connective tissue capsule that separates lymphatic tissue from neighboring tissues

What are the primary lymphatic organs? What makes them known as such?

Red Bone Marrow and Thymus

Site where T and B cells become immunocompetent: able to recognize and respond to antigens.

What are the secondary lymphatic organs? What makes them known as such?

Lymph nodes, tonsils, and spleen

Immunocompetent cells populate these tissues.

Describe the structure of red bone marrow?

Soft, loosely organized, highly vascular

Separated from osseus tissue by endosteum of bone,

What do blood cells do as they mature in the red bone marrow?

They push their way through the reticular fiber and endothelial cells to enter the sinus and flow away in the blood stream.

What systems is the thymus involved in

The endocrine, lymphatic, and immune systems.

What are the functions of the thymus?

Housing developing lymphocytes. Secreting hormones regulating their activity

The thymus is divided into lobes, what do each of those lobes have?

a cortex and medulla populated by T lymphocytes

How do your lymph nodes rank on the rarity levels of your lymphatic organs?

They are the most common

How many lymph nodes does the average person have?

~450

What are the two functions of the lymph nodes?

Cleaning the lymph

Acting as a site of T and B cell activation

Describe the structure of a lymph node

long, bean shaped structure with hilum (connecting tubes)

Enclosed with fibrous capsule and trabeculae dividing interior into compartments

What two sections are lymph nodes divided into?

The cortex and medulla

What is the name for the lymphatic vessels leading into the node?

Afferent

What is the name of the lymphatic vessels exiting the node?

Efferent

What is metastasis

cancerous cells that break free from the original tumor and travel to other sites in the body, establishing new tumors.

What is the relationship between metastasizing cells and the lymphatic system.

Cancer cells easily enter the lymphatic system and tend to lodge themselves in the first lymph node they find.

What are tonsils?

Patches of lymphatic tissue located at the entrance to the pharynx.

They are covered in epithelium,with deep pits lined with lymphatic nodules.

What do tonsils do?

Guard against ingested or inhaled pathogens

What are the 3 main types of tonsils?

Palatine tonsil

Lingual tonsils

Pharyngeal Tonsil (adenoids)

Where are the palatine tonsils

the posterior margin of the oral cavity

Where are the longual tonils?

The pair at root of tongue

Where are the pharyngeal tonsils?

single tonsil on wall of nasopharynx

What tonsil is most often infected?

The palatine tonsil

What makes the spleen special compared to other lymphatic organs?

It is the biggest

What are the two types of tissue in the spleen?

Red and White Pulp

What is red pulp?

sinuses filled with erythrocytes. will look pink on the microsope

What is white pulp?

Lymphocytes and macrophages surrounding small branches of splenic artery. Will look purple on microscope

The spleen is highly vascular and...

vulnerable to trauma and infection

What does a splenectomy leave you vulnerable for?

Future infections and premature death

What are spleen functions

Healthy RBCs pass through. Old, fragile RBCs are deconstructed. White pulp monitors blood for foreign antigens and keeps an army of monocytes for release when needed.

Stabilizes blood volume through plasma transfers to lymphatic system.

What are pathogens?

agents capable of producing disease, includes viruses, bacteria, and fungi.

What are the 3 lines of defense against pathogens

1st: Skin and Mucous Membrane

2nd: Several Innate Defense Mechanisms

3rd: Adaptive Immunity

What are some of the innate defense mechanisms in the second line of defense?

Leukocytes and Macrophages, antimicrobial proteins, natural killer cells, inflammation, and fever.

What is adaptive immunity?

When the body defeats a pathogen, it leaves the body with a "memory" of it so it can defeat it faster in the future

What do innate defenses do?

Guard equally against a broad range of pathogens

Can't remember pathogens

What are the 3 kinds of innate defenses?

Protective Proteins

Protective Cells

Protective Processes

How does skin help in pathogen defense?

It makes it mechanically difficult for microorganisms to enter the body

Keratin is tough

Skin is too dry and nutrient poor for microbial growth

Acid Mantle

Dermcidin, Defensins, and cathelicidins

What is the Acid Mantle

the thin film of lactic and fatty acids from sweat and sebum that inhibits bacterial growth

What are Dermcidins, Defensins, and Cathelicidins?

Peptides in the skin that kill microbes

Where are mucous membranes in the body and how do they protect the body?

They are in the openings to the digestive, respiratory, urinary, and reproductive tracts. That are open to the exterior.

Mucus physically traps microbes

Lyzosome enzymes destroy bacterial cell walls

How do Neutrophils kill?

phagocytosis and digestion

Or producing a cloud of bactericidal chemicals.

What is a respiratory burst?

the cloud of lyzosomes discharged from the neutrophils. It creates a killing zone around the neutrophil, destroying several bacteria

Where are eosinophils largely located?

Mucous membranes

What do eosinophils guard against

parasites, allergies, and other pathogens

How do eosinophils kill tapeworms and roundworms?

The produce superoxide, hydrogen peroxide, and toxic proteins

What do eosinophils promote and what do they limit?

They promote the action of basophils and mast cells

The limit the action of histamine and other inflammatory chemicals.

How do basophils support other leukocytes

By secreting chemicals like leukotrienes, histamine, and heparin

What does leukotrienes do?

activates and attracts neutrophils and eosinophils

What does Histamine do?

It is a vasodilator, so it increases blood flow to speed up delivery to leukocytes to the area.

What does Heparin do?

It is an anticoagulant. It inhibits clot formation. Clots would impede leukocyte mobility.

What tissue serves a similar function to basophils?

Mast Cells

What are the 3 basic categories of Lymphocytes?

T, B, and NK cells

What is the order of rarity of lymphocyte types. (common to uncommon)

T Cells (80%)

B Cells (15%)

NK Cells (5%)

What kind of immunity is each Lymphocyte type part of?

Natural Killer cells are apart of innate immunity

B Cells are part of adaptive, and helper T cells function in both

How do natural killer cells go about killing pathogens and diseased host cells?

They patrol the body looking for pathogens/diseased host cells.

Then they attack and destroy;

Bind to enemy, release perforins to polymerize a hole in enemy plasma, secrete granzymes to induce apoptosis

What are monocytes functions?

They emigrate from the blood into connective tissues and transform into macrophages

What is the macrophage system?

All the body's avidly phagocytic cells, except leukocytes.

What are wandering macrophages/where are they?

Macrophages that actively seek pathogens. They are widely distributed in loos connective tissue

What are antimicrobial proteins?

Proteins that inhibit microbial reproduction and provide short-term, innate immunity to pathogenic, bacteria, and viruses.

What are two families of antimicrobial proteins?

Interferons

Complement System

What are interferons?

Antimicrobial proteins secreted by certain cells infected by viruses

What are the benefits to the cell that secretes interferons?

There are none

What do interferons do?

They alert neighboring cells by binding to surface receptors on the neighbors surface. This protect them from becoming infected

What is the neighboring cells response when interferons alert it?

Cell synthesizes various proteins that defend it from infection; breaks down viral genes or prevents replication

Also activates NK cells & macrophages

Activated NK cells destroy the malignant cells.

Complement System

a group of 30 or more globular proteins that make powerful contributions to both innate immunity and adaptive immunity

What synthesizes and what activates the complement system? Where does it flow before being activated?

Synthesized By Liver, flows inactive in blood, activated by pathogens