LAB - Skin & Lymphoid System Flashcards
What are the major functions of the skin?
protection
thermoregulation
metabolic function (vit. D conversion, triglyceride storage, etc.)
sensation
ridges between dermis and epidermis which are unique to each individual
dermatoglyphics
- fingerprints
thymus is divided into two zones
cortex and medulla
cortex of the thymus
- highly cellular, basophilic, lobulated (septae)
- large lymphoblasts in outer cortex = mitotic figures
- inner cortex = pale staining macrophages
medulla of thymus
- mainly epithelial cells (large, pale staining nuclei with eosinophilic cytoplasm)
- Hassall’s corpuscles (keratinized epithelial cells)
lymph nodes cortex
- highly cellular and basophilic
- primary and secondary follicles
- secondary follicles have an outer mantle and an inner germinal center (proliferating B cells)
lymph nodes medulla
- paler staining than cortex
- medullary cords are an extension of the cortical mass
- medullary sinuses and trabecular extensions
lymphocytes may enter lymph nodes via:
- afferent lymphatics
- bloodstream (most of the circulating lymphocytes a=ebter the lymph nodes like this)
red and white pulp
spleen
white pulp can be differentiated by other lymphoid nodules by the presence of a …..
central artery
what are the functions of the spleen?
- filter blood (particulate matter, bacteria, old/defective RBCs)
- red cells are modified in spleen as well
- production of an immune response to blood borne pathogens
are lymphatic vessels present in the spleen?
NO
flow of blood through spleen
- splenic artery
- branches repeatedly = central arteries
= short branches at right angles (pencillary arteries)
= each terminates in 2-3 sheathed capillaries 9blind ended capillaries; no endothelial lining; surrounded by macrophage aggregation instead); blood enters red pulp
= blood squeezes out through walls of sinuses to drain into larger sinuses
= drain into splenic vein and leave the spleen
where are T cells located in the spleen?
periarteriolar lymphoid sheath
what type of epithelium covers the tonsils?
stratified squamous non-keratinizing
- have a partial capsule; palatine tonsil = hemi-capsule where the tonsil sits in surrounding connective tissue
nervous tissue consists of:
- neurons: functional cells > Pyramidal cells, Stellate cells, Martinotti cells - neuroglial cells > astrocytes > microglia > oligodendrocytes > ependymal cells
T or F. nerve tissue has connective tissue
F! but has glial cells which perform similar functions of support, protection and nutrition
Luxol Fast Blue
stains myelin sheath blue and nuclei
Nissl substance are purple
nerve fibers within myelin sheaths are unstained
astrocytes
- most numerous glial cell in grey matter
- metabolic exchange between neurons and blood
- provide structural support to neurons
- metabolic exchange between neurons and blood
- important for repair of CNS tissue after injury or disease
microglia
- small cells with irregular nuclei
- little cytoplasm = fine, highly branched processes
- monocyte-macrophage defense system
oligodenrocytes
- medium cells with a number of short, branched processes
- myelination of acons in the CNS
ependymal cells
- make up the simple, cuboidal lining of the ventricles in the brain and spinal cord
- don’t rest on BM
- cilial function to propel the CSF within the ventricles
- microvilli = absorptive and secretory functions
COUNTERSTAIN OF LFB
CRESYL VIOLET ACETATE
