IC6 Anatomy and Histology Flashcards
(38 cards)
What are some lymph nodes all over the body?
- Tonsils,
- adenoid,
- lymph node,
- spleen,
- Peyer’s patches in small intestine
What are the primary lymphoid tissues and the secondary lymphoid tissues?
Primary lymphoid tissues: thymus and bone marrow
Secondary Lymphoid tissues: spleen and lymph node
How does lymph travel in the lymphatic system? Which lymphatic vessels are the ones that connect back to the circulatory system?
Blood capillaries –> lymphatic capillaries –> lymph nodes –> lymphatic vessels –> blood vessels
Left and right subclavian trunk –> Thoracic duct and right lymphatic duct respectively
Where is the thymus(1)?
Above heart, in between lungs
In anterior mediastinum
What are the gross anatomy of thymus(1)?
2 lobes
Each lobe has many smaller lobules
Each lobule has cortex and medulla
NO afferent lymphatic vessels
Only efferent lymphatic vessels
What cells are present in the thymus(1) cortex? What process occurs at the thymus cortex?
Cortex:
- Lymphocytes
- LESS Epithelial reticular cells
a. Ensheath the capillaries
Site for T cells precursor proliferation
+ Blood thymus barrier
What cells are present in the thymus (1) medulla?
Medulla:
- MORE epithelial reticular cells
a. Produces thymosin and thymopoietin –> stimulate T cell differentiation and proliferation - Hassall’s corpuscles (group of epithelial cells)
- LESS lymphocytes –> enter blood circulation in medulla OR cortico-medullary junction to populate T-dependent areas of other lymphoid organs
- Macrophages
- Endothelial cells
What are the functions of thymus?
- T lymphocytes differentiation
- Selective removal of cells
Positive selection –> T cells that can bind to MHC I and MHC II
Negative Selection –> T cells that only bind to 1 and do not bind to self-antigen - Secretes hormones e.g. thymosin
What is the gross anatomy of the lymph node(2)?
Hilum
Afferent & Efferent Lymphatic vessels
Capsule & Trabecular
Cortex & Medulla
Paracortical zone
What is the outer layer of the lymph node(2) and what’s underneath it?
Capsules
Subcapsicular sinuses
What vessels are at the hilum of the lymph node(2)?
Artery
Veins
Efferent Lymphatic Vessel
What is in the lymph node(2) cortex? What cells are there?
Cortex:
Many lymphatic Nodules/follicles, contains
- Germinal centers
- Mainly B cells
- Other cells: Plasma cells, macrophages, dendritic cells, reticular cells
What is in the lymph node(2) medulla? What cells are there?
Medulla:
Medullary cords and medullary sinuses
- B cells (& some T cells)
- Plasma cells
- Reticular cells
- Dendritic cells
Where is the paracortical zone in the lymph node (2)? What cell is abundant there?
Lie between cortex (lymphatic nodules) and medulla
- Many T cells
What is the function of the lymph node?
- Trap foreign substances by APC
- Optimize chance of antigen meeting lymphocyte
- Lymph travels through it
How do the lymphocytes circulate in the lymph node(2)? (Enter and leave)
- Lymphocytes enter lymph –> enter lymph node via afferent lymphatic vessels
OR - Lymphocytes enter from blood into lymph node through the walls of high endothelial venules / post capillary venules (in lymph node)
Lymphocytes leave lymph node via efferent lymphatic vessels
What are the differences between lymph node and spleen?
- Lymphoid nodules with B cells and germinal center: YES YES
- Lymphoid nodules have central Arteriole: NO YES
- Parts:
Cortex
Medulla
Paracortical zone
White Pulp
Red Pulp
What is in the white pulp of the spleen(3)?
White pulp:
- Lymphoid nodules / follicles, contains
- B cells
- Germinal centers - Periarterial lymphatic sheaths (PALS) surrounding central arterioles
- PALS contain T cells
What is in the red pulp of spleen(3)?
Red pulp:
- Splenic cords / Red pulp cords / Billroth’s cords, contains
- Blood cells, macrophages, lymphocytes, plasma cells, reticular fibers - Splenic sinusoids (venous sinus)
- Wide irregular lumen –> drain into pulp veins –> drain into trabecular veins
- Discontinuous lining of endothelial cells (stave cells)
What is the function of the spleen(3)?
- Immunological filter of blood
- Destroy old RBCs
How do the lymphocytes circulate in the spleen(3)? (Enter and leave)
Lymphocytes enter spleen
–> enter at the trabecular artery
–> central arteriole
–> splenic sinusoids
–> trabecular vein
What are the parts of the adenohypophysis/anterior pituitary(4)?
Pars Distalis
Pars Intermedia
Pars Tuberalis
What cells are present in the anterior pituitary(4)? What are the hormones produced in there?
- Pars Distalis:
Chromphils
- Acidophils (light stained)
o Somatotrophs (Growth hormones)
o Mammotrophs (Prolactin)
- Basophils (dark stained)
o Gonadotrophs (FSH, LH)
o Corticotrophs (ACTH )
o Thyrotrophs (TSH)
Chromophobes (translucent cells)
- Degranulated chromophils
- Pars intermedia:
- Melanotrophs (meloncyte stimulating hormone) - Pars tuberalis:
- Undifferentiated cells (gondatrophs)
- Mostly chromophobes
- Some acidophils and basophils
What are the parts of neurohypophysis/ posterior pituitary? What are the hormones stored in there?
Pars Nervosa:
- Axons of hypothalamus
- Pituicytes (support storage and release of hormones)
- Herring bodies (store hormones, extension of axons)
- Large number of capillaries
Hormones:
- Antidiuretic hormones (ADH)
- Oxytocin (love hormone)
Stored in neurohypophysis as granules (herring bodies) in axons
