4/3 Lecture E1 Flashcards
How many more bacterial cells are there in the body than human cells?
10x
True or False: The immune system is an organ
false: it is a population of cells that inhabit all organs and defends the body from agents of disease
What does the lymphatic system do? (4 basic steps)
1) Recover fluid
2) Inspect fluid for disease agents
3) Activate immune responses
4) Returns fluid to the bloodstream
What are the three functions of the lymphatic system?
1) Fluid recovery
2) Immunity
3) Lipid absorption
Where does fluid filter from?
blood capillaries and tissue spaces
how much fluid (%) do blood capillaries reabsorb?
85%
How much of our body’s water and plasma enter the lymphatic system, to be returned to the blood after filtering? (per day)
15% (2-4 L/day) and about half of the plasma
What is the lymphatic system filtering for?
foreign cells and chemicals from the tissues
Where are the filtered foreign cells and chemicals taken?
lymph nodes
where does lipid absorption occur and what is the agent the absorbs it?
the small intestine by Lacteals
What is the role of lymphatic vessels?
to transport lymph
What are lymphatic tissues composed of?
aggregates of lymphocytes and macrophages
What separates lymphatic organs from surrounding organs?
connective tissue capsules
What is lymph originally?
extracellular fluid drawn into lymphatic capillaries
Which has more proteins: Plasma or Lymph?
Lymph
Lymphatic capillaries penetrate nearly every tissue in the body except: (4)
cartilage, cornea, bone, and bone marrow
What is the capillary wall structure like?
endothelial cells overlapping each other like roof shingles, closed at one end
How are capillaries tethered to the surrounding tissue?
by protein filaments
When are the endothelial valve-like flaps open and when are they closed?
open during high pressure, closed during low pressure
what are the three layers of larger lymphatic vessels?
1) Tunica interna: endothelium and valves
2) Tunica media: elastic fibers, smooth muscle
3) Tunica externa: thin outer layer
How many lymphatic trunks are there and where are they?
6:
1) jugular
2) subclavian
3) bronchomediastinal
4) intercostal
5) intestinal (unpaired)
6) lumbar trunks
How many collecting ducts are there and what are they?
2:
1) right lymphatic duct
2) thoracic duct
What areas of the body does the right lymphatic duct receive lymph from?
the right arm and the right side of head and thorax.
Where does the right lymphatic duct empty?
into the right subclavian vein
What areas of the body does the thoracic lymphatic duct receive lymph from?
receives lymph from below diaphragm, left arm, left side of head, neck, and thorax.
Where does the thoracic lymphatic duct empty?
empties into the left subclavian vein
describe the thoracic duct as compared to the right lymphatic duct.
larger and longer, begins as a prominent sac in abdomen called the cisterna chyli.
What is the cisterna chyli?
a sac that forms the beginning of the thoracic duct
Approximately how long is the thoracic lymphatic duct?
45 cm
Approximately how long is the right lymphatic duct?
1.25 cm
Where is the cisterna chyli located?
anterior to the 2nd lumbar vertebrae
Which flows with more pressure and speed: venous blood or lymph?
venous blood
What stimulates contractions of lymphatic vessels and also aids in flow? (6)
stretching of vessels by lymph fluid, aided by skeletal muscle contractions, arterial pulsation, thoracic “pump”, exercise, rapidly flowing blood in subclavian veins.
What are the 6 types of lymphatic cells?
1) Natural Killer cells (NK Cells)
2) T Lymphocytes (T cells)
3) B Lymphocytes (B cells)
4) Macrophages
5) Dendritic cells
6) Reticular cells
Describe NK cells
Large lymphocytes. Attack and destroy bacteria, transplanted tissue, host cells infected with viruses or that have turned cancerous
Where do T cells mature?
Thymus
What does the activation of B cells cause?
proliferation and differentiation into plasma cells that produce antibodies.
What do macrophages develop from?
monocytes
What do macrophages do?
Phagocytize tissue debris and process foreign matter and alert the immune system
What do macrophages phagocytize?
dead neutrophils, bacteria and other foreign matter
What category of cell are macrophages considered?
Antigen-presenting cells (APCs)
Which lymphocytes are considered APCs?
macrophages, dendritic cells, and reticular cells.
How do dendritic cells alert the immune system to pathogens that have breached the body surface?
engulf antigens then migrate to lymph nodes
Where are dendritic lymphocytes found? (3)
epidermis, mucous membranes, and lymphatic organs
which are mobile: dendritic cells or reticular cells?
dendritic. reticular cells are stationary.
To what do the reticular cells contribute to?
to the stroma of a lymphatic organ.
Define Lymphatic (lymphoid) tissue
aggregations of lymphocytes in the connective tissue of mucous membranes and various organs.
What is the simplest form of lymphatic tissue?
diffuse
Where is lymphatic tissue most prevalent?
body passages open to the exterior: respiratory, digestive, urinary, and reproductive tracts; Mucosa-associated lymphatic tissue (MALT)
What is GALT
gut-associated lymphoid tissue (Peyer’s patches found in the lining of the distal small intestine)
What is BALT
bronchus-associated lymphoid tissue
What is NALT
nasal-associated lymphoid tissue
What is CALT
conjunctival-associated lymphoid tissue
What is LALT
Larynx-associated lymphoid tissue
What is SALT
skin-associated lymphoid tissue
What is VALT
vulvo-associated lymphoid tissue
What are lymphatic nodules (follicles)
dense masses of lymphocytes and macrophages that congregate in response to pathogens
Where are lymphatic nodules abundant
lymph nodes, tonsils, and appendix
what separates lymphatic organs from neighboring tissues?
A connective tissue capsule
What are primary lymphatic organs?
red bone marrow and the thymus
where are T and B cells able to recognize and respond to antigens?
Primary lymphatic organs
What are the secondary lymphatic organs?
lymph nodes, tonsils, and spleen
Where do immunocompetent cells populate?
secondary lymphatic tissues
What two activities is red bone marrow involved in?
hematopoiesis and immunity
where is red bone marrow mostly found?
flat bones (pelvic and sternum) and somewhat in the heads of fermur/humerus
where do blood cells go after they mature?
push their way through the reticular and endothelial cells to enter the sinus and flow away into the bloodstream.
What systems does the Thymus belong to?
endocrine, lymphatic, and immune
What is the role of the Thymus?
houses developing lymphocytes, secretes hormones regulating lymphocyte activity
Where is the thymus located?
in superior mediastinum between sternum and aortic arch
What divides the Thymus into lobes?
trabeculae
What type of cell is found in the Medulla of the Thymus?
Mature T cells
Why is the blood-thymus barrier important?
Keeps immature cells separated from circulation
What 5 signaling molecules does the Thymus produce
thymosin, thymopoietin, thymulin, interleukins, interferons
What type of cell is found in the cortex of the thymus?
Immature T cells
What is the most numerous of lymphatic organs?
lymph nodes
What two functions do lymph nodes perform?
1) cleans up the lymph
2) acts as a site of T and B cell activation
are the vessels of the hilum of the lymph nodes afferent or efferent?
efferent
Where are the afferent vessels of lymph nodes located?
along its convex surface.
Where in lymph nodes do B cell multiply and differentiate into plasma cells?
germinal centers within the cortex
What do cervical lymph nodes monitor?
lymph coming from the head and neck
where do axillary lymph nodes receive lymph from?
upper limbs and breasts
where do thoracic lymph nodes receive lymph from?
mediastinum, lungs, and airway
what do abdominal lymph nodes monitor?
lymph from the urinary and reproductive systems
Which lymph nodes monitor lymph from the digestive tract?
intestinal and mesenteric lymph nodes
Where do the inguinal lymph nodes receive lymph from?
the entire lower limb
Where do the popliteal lymph nodes receive lymph from?
the leg
where are T cells within lymph nodes?
paracortex (inner)
where are B cells within lymph nodes?
cortex (outer)
what is found in the medulla of lymph nodes?
plasma cells, lymphocytes, macrophages etc
What two things can happen when a lymph node is under challenge by an antigen?
1) lymphadenitis
2) lymphadenopathy
What is the normal size of lymph nodes?
1 cm or less
what is the normal size of inguinal lymph nodes?
2 cm
what are pharyngeal tonsils also known as
adenoids
What are the most often infected tonsils?
Palatine tonsils
What is the body’s largest lymphatic organ
Spleen
What two types of tissue does the parentchyma of the spleen exhibit?
1) Red pulp: RBCs!
2) White pulp: lymphocytes and macrophages around small branches of splenic artery
What are the functions of the Spleen?
1) healthy RBCs come and go
2) “erythrocyte graveyard”
3) blood cell production in fetus (and anemic adults)
4) white pulp monitors blood for foreign antigens and release monocytes when needed
5) stabilizes blood volume through plasma transfers from blood to lymphatic system
What is a common issue with a splenectomy?
leaves someone susceptible to infections, especially encapsulated bacteria like streptococcous
Define pathogens
agents capable of producing disease
what categories do pathogens include?
viruses, bacteria, and fungi
What is the first line of defense?
skin and mucous membranes
what is involved in the second line of defense? (6)
leukocytes and macrophages, antimicrobial proteins, natural killer cells, inflammation, and fever
What is involved in the third line of defense?
adaptive immunity: defeat of pathogen and memory for faster future defeat
what are the three types of innate defenses?
1) protective proteins: C’ cascade, interferons etc
2) Protective cells: PMNs, macrops, etc
3) protective processes: fever, inflammation, etc
what is characteristic of innate defenses?
local, nonspecific, lacks memory
What is the acid mantle and what is it a feature of
a thin film of lactic and fatty acids from sweat and sebum that inhibits bacterial growth: skin.
What are the three peptides in skin that kill microbes?
dermicidin, defensins, and cathelicidins
Where are mucous membranes located?
In areas that are open to the exterior (digestive, respiratory, urinary, and reproductive tracts)
What do head fluids contain?
lysozyme: an enzyme that destroys bacterial cell walls
Where can you find viscous hyaluronic acid?
subepithelial areolar tissue
What are the 5 types of leukocytes?
1) Neutrophils
2) lymphocytes
3) monocytes
4) eosinophils
5) basophils
Which leukocytes are polymorphonuclear (have granules and lobed nuclei)?
1) neutrophils
2) eosinophils
3) basophils
What 2 ways can neutrophils kill bacteria?
1) phagocytosis and digestion
2) bactericidal chemical cloud (using lysosome degranulation)
Where are eosinophils especially found?
mucous membranes
What do eosinophils guard against?
parasites and allergens
How do eosinophils kill tapeworms and roundworms?
By producing superoxide, hydrogen peroxide, and toxic proteins
What do eosinophils promote the action of?
basophils and mast cells
What do basophils do?
secrete chemicals that aid in the mobility and action of other leukocytes
What chemicals to basophils secrete (also secreted by mast cells!)? (3)
1) leukotrienes
2) histamine
3) heparin
What do leukotrienes do?
activate and attract neutrophils and eosinophils
What does histamine do?
Its a vasodilator: increases blood flow in order to speed delivery of leukocytes
What does heparin do?
inhibits clot formation (clots would impede leukocyte mobility!)
What are the three categories of lymphocytes (in order of abundance)?
T, B, and NK cells
Of T, B and NK cells, which are a part of innate immunity and which are adaptive?
NK cells are innate and B cells are adaptive. T cells are both
What substances are involved in the macrophage system?
all of the body’s avidly phagocytic cells, except leukocytes
What do monocytes transform into?
macrophages
What are the two types of macrophages?
wandering and fixed
Where are wandering macrophages found?
widely distributed in loose connective tissue
What are the three fixed macrophages?
1) Microglia: CNS
2) Alveolar: in lungs
3) Hepatic: in liver
