mesenchyme tissue
benign: fibroma, lipoma
malignant: sarcoma
melonocytes
benign: nevus
malignant: melonoma
lymphocytes
malignant: lymphoma
epithelium
benign: adenoma, papilloma
malignant: carcinoma, adenocarcinoma
90% of head and neck cancers are ?
squamous cell carcinomas
types of metastasis
transcoelomic
- from abdominal cavity and pelvic cavity
metastasis
dissemination of malignant tumors thru body
hematogenous
spread thru blood
lymphogenous
main route for carcinomas (epithelial)
blood vessels form a — circulation
closed
what kind of system are lymphatic vessels?
form a one-way system in which lymph flows ONLY toward heart
components of lymphatic system
primary lymphoid organs
secondary lymphoid organs
-where most lymphocytes are activated by antigen presentation, include MALT (mucosa-assoc lymphoid tissue), lymph nodes, and spleen
T and B lymphocytes
MALT
pharyngeal tonsil, palatine tonsil, and lingual tonsil
lymph nodes
bean-shaped, encapsulated structures, distributed thru body along lymphatic vessels
3 regions of lymph nodes
outer cortex
paracortex
medulla
outer cortex of lymph node
- contains lymph nodules with a germinal center (where mature B cells proliferate, differentiate)
paracortex
where most lymphocytes enter HEVs (high endothelium veins)
-also rich in T cells
medulla
with sinuses converging at the efferent lymphatic
spleen
2 major regions of spleen
white pulp: cluster of lymphocytes. makes up 20% of spleen
red pulp: where worn out red blood cells are destroyed, so it contains huge numbers of erythrocytes and macrophages that engulf them
what start the transport of lymph?
lymphatic vessels and then flows thru successively larger and thicker channels