Chapter 22 - Lymphatic System & Immunity Flashcards
Immunity/Resistance
ability to ward off damage or disease
(2) types of immunity
**Innate - **non specific
1st/2nd line of defense
**Adaptive - **specific recognition of invaders
Lymphatic system
lymph, lymphatic vessels, structures & organs containing lymphatic tissue & red bone marrow
Functions of Lymphatic system
drain excess interstitial fluid
transport dietary lipids
carry out immune responses
Lymphatic vessels begin as lymphatic ____
capillaries - closed at one end
Lymphatic capillaries unite to form large lymphatic ____
vessels - resemble veins in structure but thinner walls & more valves
Lymphatic: Capillaries → vessels → ???
passes through lymph nodes
Lymph nodes
Encapsulated organs with masses and B and T cells
Lymphatic capillaries
larger diameter than blood capillaries
unique one-way structure
permit intersitial fluid to flow in but not out
anchoring filaments pull opening wider when interstitial fluid accumulates
Lacteals
specialized lymphatic capillaries in small intestine that carry dietary lipids into vessels & then blood
Chyle
lymph with lipids
Vessels exit lymph nodes to form lymph ___
trunks
Principal lymph trunks are…? (5)
lumbar
intestinal
bronchomediastinal
subclavian
jugular
Lymph passes from lymph trunks into (2) main channels before draining into…
thoracic & right lymphatic ducts
venous blood
Most components of blood plasms filter freely though capillary walls to form interstitial fluid but more fluid filters out of blood capillaries than returns to them by …`
reabsorption
excess filtered fluid drains into?
lymphatic vessels & becomes lymph
lymph
interstitial fliud in lymphatic vessels
Important function of lymphatic vessels
to return lost plasma proteins to blood stream
(2) pumps aiding venous return also used maintain flow of lymph
1) skeletal muscle pump
2) respiratory
Lymphatic tissue & organs
(2) groups based on function
1) primary lymphatic organs
2) secondary lymphatic organs
primary lymphatic organs
sites where stem cells divide and become immunocompetent
- red bone marrow & thymus
Secondary lymphatic organs
where most immune response occurs
lymph nodes, spleen, lymphatic nodules
Thymus
in mediastinum between sternum & aorta
- 2 lobes seperated by capsule but held close by connective tissue
**trabeculae **(extensions of capsule) divide each lobe into lobules
- outer **cortex **& inner medulla
Outer cortex of Thymus
composed of many **T cells **which came from red bone marrow
**Dendritic cells **derived from monocytes assist in T cell maturation
specialized **epithelial cells **assist in T cell maturation
- **macrophages **clear out dead cells
Medulla
scattered, nore mature T cells
epithelial, dendritic cells & macrophages
Lymph nodes
located?
~600 scattered throughout body
located along lymphatic vessels
STROMA: structural framework
covered by **capsule **that has **trabeculae **which divides nodes into compartments
reticular fibers & fibroblasts internal to capsule
**PARENCHYMA: **functioning part
divided into cortex (inner + outer) & medulla
**Parenchyma **of Lymph Node
Outer cortex - aggregates of B cells (lymphatic nodules/follicles)
– site of plasma cell and memory B cell formation
**Inner cortex - **mainly T cells & dendritic cells
**Medulla - **B cells, macrophages, antibody producing plasma cells from cortex
Flow of Lymph - one direction
enters through **afferent lymphatic vessels → subscapular sinus → traneculae sinus → medullary sinus → efferent lymphatic vessels **
Lymph nodes function as ___
filter
foreign substances trapped by reticular fibers & destroyed by macrophages
Spleen
largest single mass of lymphatic tissue in body
Spleen
consists of?
**Stroma **
**Parenchyma **
**Parenchyma **of spleen
consists of (2) different kinds of tissue
- *White pulp **- lymphatic tissue (lymphocytes and
macrophages) arranged around central arteries (branches of splenic artery) - B & T cells carry out immune function
**Red pulp **- blood-filled **venous sinuses **& **splenic cords ** (RBCs, macrophages, lymphocytes, plasma cells & granulocytes
Within red pulp, spleen performs (3) functions
1) removal of ruptured RBCs by macrophages
2) storage of platelets
3) hemopoiesis - production of blood cells
Lymphatic nodules
not surrounded by capsule
Scattered throughout lamina propria of mucous membranes lining GI, urinary, reproductive tract (**Mucosa-associated Lymphatic tissue - MALT) **
small & solitary
larger - Tonsils, Peyers patches & appendix
Innate Immunity
first line of defenses?
provides…
: Skin and mucous membranes
both physical & chemical barriers
**Innate Immunity **- Physical barriers
epidermis
mucous membranes
nose hairs
cilia of upper respiratory tract
**Innate Immunity - **Fluids
Lacrimal apparatus of eye
Saliva
Urine
Vaginal secretions, defecation & vomiting
**Innate Immunity - **chemicals
sebaceous (oil) glands secrete sebum
perspiration, gastric juice & vaginal secretions - (all acidic)
Innate Immunity - 2nd line of defense?
Internal defenses
**Innate Immunity - **Antimicrobial substances
**Interferons ** - produced by lymphocytes, macrophages & fibroblasts
**complement system - **proteins in blood plasma & PMs enhance immune rxns
Iron-binding proteins - inhibit bacteria growth by reducing available iron
**Antimicrobial Proteins (AMPs) - **attract dendritic & mast cells that participate in immune responses
Innate Immunity
- Natural Killer (NK) cells
Lymphocyte but not a B or T cell
- can kill variety of infected bodies & certain tumour cells
- attack any cell displaying abnormal plasma membrane proteins
release **perforin **or **granzymes **
**Innate Immunity - **phagocytes
**Neutrophils & **macrophages **
migrate to infected area
(5) steps of phagocytosis
- chemotaxis, adherence, ingestion, digestion, killing
