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