Chapter 13 - the lymphatic system

function of lymphatic system

• fluid balance

• fat absorption

• defense

large lymphatic vessels are similar to

veins in the cardiovascular system

2 ducts in the lymphatic system

thoracic (left side) and right lymphatic (right side)

one-way system =

single layer of squamous epithelium

lymph

interstitial fluid in lymphatic vessels

valves

lymph forced through vessels is prevented from flowing backward by one-way valves

thoracic duct drains this area of the body

left subclavian vein

-returns lymph collected from the body below thorax

right lymphatic duct drains this are of the body

left subclavian vein

primary lymphatic organs: why primary?

pivotal role in immunity

red bone marrow

site of stem cells that are capable of diving and producing blood cells

thymus gland location

thoracic cavity; between the trachea and sternum (superior to the heart)

secondary lymphatic organs: why secondary?

places where lymphocytes encounter and bind with antigens after they become active cells

spleen

largest lymphatic organ

• red pulp: filters blood

• white pulp: concentration of lymphocytes

lymph nodes

small; located alone lymphatic vessels

lymphatic nodules

concentration of lymphatic tissue NOT surrounded by a capsule

tonsils

lymphatic nodules located in posterior pharynx

Peyer’s patches

lymphatic organs in the small intestine

appendix

small appendage extending outward from the cecum of large intestine

nonspecific defenses: barriers to entry

• physical and chemical

• first line of defense against infection

  • physical: skin and mucous membranes

  • chemical: secretions of glands in skin (sweat, saliva, tears)

inflammatory reaction: nonspecific

accompanied by action of phagocytic cells, NK cells, and protective proteins

4 cardinal signs of inflammation

1. redness

2. swelling

3. heat

4. pain

5 steps in inflammatory response

1. chemical reaction

2. increased capillary permeability

3. edema and clots form

4. migration of phagocytes

5. monocytes transform to macrophages

why aren’t NK cells part of the specific defenses

they have no specificity for individual pathogens

protective proteins: complement

proteins in plasma; aid general defense by destroying bacteria

how complement proteins “complement” the immune response

they amplify the response because proteins attract phagocytes

interferon: role in protection against viruses

prepare for possible attack by producing substances that interfere with viral replication

clonal selection

antigen will select which lymphocyte will undergo expansion and produce more lymphocytes bearing the same type of receptor

clonal expansion =

more daughter cells

specific defenses: plasma cells

undergo apoptosis (death/destruction)

specific defenses: memory cells

divide and give rise to more lymphocytes capable of quickly producing antibodies

antibodies

y-shaped protein molecule with two arms (heavy and light chains)

antigen binding sites

variable regions, dependent on structure of antibody

antibodies: functions

react with viruses and toxins by coating them completely (neutralization)

role of antigen-presenting cells in T cell activation

allows T cell to compare antigen and self protein → goes on to destroy cells carrying foreign antigens

cytotoxic T cells (CD8)

destroy antigen-bearing cells (virus/cancer cells)

perforin

punch holes into invading cell’s plasma membrane forming a pore that allows destructive enzymes to enter

vaccines

substances that contain an antigen to which to immune system responds

active immunity

develops after a person is infected with a pathogen

what makes active immunity “active”

B + T memory cells remain

where antibodies come from

the individual alone produces them in their body

what makes passive immunity “passive”

the individual receives prepared antibodies from another person (temporary)

monoclonal antibodies

from lymphocyte that has fused with a cancer cell

how monoclonal antibodies are made

produced by plasma cells derived from the same B cell

allergies

hypersensitivities to substances that ordinarily would do no harm to the body

hay fever

seasonal; sneezing, swelling of nasal mucosa, asthmatic symptons

asthma

condition in which bronchioles constrict and cause difficulty breathing

anaphylactic shock

allergen has entered the bloodstream; sudden and life-threatening, drop in BP

tissue rejection

recipients immune system recognizes that tissue is not from “self”

role of immunosuppressive drugs

organ rejection prevention

autoimmune disease

immune system mistakenly attacks body’s own tissues

autoimmune disease: myasthenia gravis

muscle weakness

autoimmune disease: rheumatoid arthritis

inflammation of joints; causing cartilage destruction, bone erosion, and joint deformities

titer

amount of antibody present in blood plasma sample

immune deficiency

immune system is unable to protect against disease

immune deficiency: AIDS

patients show greater susceptibility to a variety of diseases with higher risk of cancer

immune deficiency: SCIDs

genetic disorder; both antibody and cell mediated immunity are lacking

effects of aging

• more susceptible to infection

• immune system exhibits lower levels of function

• thymus gland degenerates

  • number of T cells decreases and no longer responds to foreign antigens

lymphatic system: homeostasis

• lymphatic helps digest by absorbing fats

• assists cardiovascular by absorbing excess tissue fluid

• protect from infectious diseases

• helps skeletal system by filtering

• immune, nervous, and endocrine systems influence immune response

2 functions of thymus gland

• produce thymosins

• site where T lymphocytes mature

lymphatic system: additional info

• takes up excess interstitial fluid and returns it to the circulation

• houses WBC

• lacteals in the intestines absorb dietary lipids