LAB - Skin & Lymphoid System

Question 1

What are the major functions of the skin?

Answer 1

protection
thermoregulation
metabolic function (vit. D conversion, triglyceride storage, etc.)
sensation

Question 2

ridges between dermis and epidermis which are unique to each individual

Answer 2

dermatoglyphics

- fingerprints

Question 3

thymus is divided into two zones

Answer 3

cortex and medulla

Question 4

cortex of the thymus

Answer 4

• highly cellular, basophilic, lobulated (septae)
• large lymphoblasts in outer cortex = mitotic figures
• inner cortex = pale staining macrophages

Question 5

medulla of thymus

Answer 5

• mainly epithelial cells (large, pale staining nuclei with eosinophilic cytoplasm)
• Hassall’s corpuscles (keratinized epithelial cells)

Question 6

lymph nodes cortex

Answer 6

• highly cellular and basophilic
• primary and secondary follicles
• secondary follicles have an outer mantle and an inner germinal center (proliferating B cells)

Question 7

lymph nodes medulla

Answer 7

• paler staining than cortex
• medullary cords are an extension of the cortical mass
• medullary sinuses and trabecular extensions

Question 8

lymphocytes may enter lymph nodes via:

Answer 8

• afferent lymphatics

- bloodstream (most of the circulating lymphocytes a=ebter the lymph nodes like this)

Question 9

red and white pulp

Answer 9

spleen

Question 10

white pulp can be differentiated by other lymphoid nodules by the presence of a …..

Answer 10

central artery

Question 11

what are the functions of the spleen?

Answer 11

• 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

Question 12

are lymphatic vessels present in the spleen?

Answer 12

NO

Question 13

flow of blood through spleen

Answer 13

• 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

Question 14

where are T cells located in the spleen?

Answer 14

periarteriolar lymphoid sheath

Question 15

what type of epithelium covers the tonsils?

Answer 15

stratified squamous non-keratinizing

- have a partial capsule; palatine tonsil = hemi-capsule where the tonsil sits in surrounding connective tissue

Question 16

nervous tissue consists of:

Answer 16

- neurons: functional cells
> Pyramidal cells, Stellate cells, Martinotti cells
- neuroglial cells
> astrocytes
 > microglia
 > oligodendrocytes
 > ependymal cells

Question 17

T or F. nerve tissue has connective tissue

Answer 17

F! but has glial cells which perform similar functions of support, protection and nutrition

Question 18

Luxol Fast Blue

Answer 18

stains myelin sheath blue and nuclei
Nissl substance are purple
nerve fibers within myelin sheaths are unstained

Question 19

astrocytes

Answer 19

• 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

Question 20

microglia

Answer 20

• small cells with irregular nuclei
• little cytoplasm = fine, highly branched processes
• monocyte-macrophage defense system

Question 21

oligodenrocytes

Answer 21

• medium cells with a number of short, branched processes

- myelination of acons in the CNS

Question 22

ependymal cells

Answer 22

• 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

Question 23

COUNTERSTAIN OF LFB

Answer 23

CRESYL VIOLET ACETATE