IC6 Flashcards
The lymphoid (lymphatic or immune) system consists of cells, tissues and organs that are involved in the ______
defense of the body against invasion by bacteria, viruses and other foreign bodies.
Examples of primary lymphoid tissue
Thymus, bone marrow
Diff btw Primary and secondary Lymphoid tissue
Primary: origin of lymphocytes
Secondary: where lymphocytes reside and function
Shape of lymph nodes
Bean-shaped
B lymphocytes differentiate and mature in the ______
bone marrow
T lymphocytes differentiate and mature in the ____
thymus
Location of thymus
Between lungs, above heart
Change in thymus over time
Becomes more fibrous and fat as it has encountered more antigens hence become less active
Does thymus contain afferent and efferent vessels?
no afferent lymphatic vessels but efferent vessels are present
Epithelial reticular cells (EC) are thought to produce thymosin and thymopoetin, which promote _____
T cell differentiation and proliferation
Negative selection in medulla allows survival only of ______
T cells that do not tightly bind self antigens presented by dendritic cells there
Positive selection in cortex allows survival only of _____
T cells with functional TCRs recognizing both MHC I and II molecules
Location of lymph nodes
Thorax (near armpit) & abdomen
Do lymph nodes contain afferent and efferent vessels?
Yes for both
Lymphocytes in the blood enter through the walls of postcapillary venules (also known as _____) in the lymph node
high endothelial venules
Which organ is the largest single lymphoid organ?
Spleen
What is the red and white pulp found in the spleen?
Red pulp: splenic cord
White pulp: lymphatic nodule
Red pulp cords is also known as ____
Billroth’s cords
Splenic sinusoids are characterised by
▪ Wide and irregular lumen
▪ Discontinuous lining of endothelial cells (stave cells)
Type of cells in the anterior pituitary
*Chromophils (secretory cells in which hormone is stored in cytoplasmic granules)
– Acidophils
– Basophils
*Chromophobes (degranulated chromophil cells)
*Melanotrophs
Various hormones secreted by acidophils
– Acidophils
* Somatotrophs (growth hormone)
* Mammotrophs (prolactin)
Various hormones secreted by basophils
– Basophils
* Gonadotrophs (FSH, LH )
* Corticotrophs (ACTH or corticotropin)
* Thyrotrophs ( TSH )
Various hormones secreted by melanotrophs
Melanotrophs
-Melanocyte stimulating hormone
Parts of the pituitary gland
Anterior - Pars distalis, Pars intermedia, Pars tuberalis
Posterior - neural stalk, pars nervosa
control of anterior pituitary function
Anterior pituitary control by the hypothalamic hypohyseal portal system (primary and secondary capillary plexus)
Additional control is by negative feedback which depends on plasma levels of hormones secreted by the anterior pituitary
2 functional groups of hormones
Hormones directly acting on non-endocrine tissues e.g. growth
hormone, prolactin, ADH
Hormones modulating the activity of other endocrine glands e.g. TSH, FSH, LH, adrenocorticotrophic hormone (ACTH)
control of posterior pituitary function
Posterior pituitary secretion -Hypothalamic hypophyseal tract (Axons)
structure of the adrenal medulla
Large polyhedral and pale staining chromaffin cells
Identify the three layers of the adrenal cortex and its respective hormones
Zona Glomerulosa (aldosterone)
Zona fasciculata (glucocorticoids, adrenal androgens)
Zona reticularis (glucocorticoids, Androgens)
Pancreas – differentiate the islets of Langerhans from the exocrine cells
Endocrine cells appear rounded or
polygonal,smaller and lightly stained than exocrine cells
different types of islet cells
Alpha, beta, Delta, PP/F cells
Role of oxytocin
Oxytocin causes uterine contraction during labour and milk expulsion from mammary gland
Role of ADH
ADH mainly acts on renal tubules, reducing urinary flow by increasing water absorption
Organs not under pituitary control
Pancreas , Adrenal medulla , Parathyroid
adenohypophysis refer to ___
anterior pituitary
Neurohypophysis refer to ___
Posterior pituitary
Action of somatostatin (secreted by Delta cells of islets of Langerhans)
suppresses release of insulin, glucagon
Action of pancreatic polypeptide (secreted by PP/F cells of islets of Langerhans)
inhibits secretion of pancreatic enzymes
Is epithelial reticular cells (EC) more in thymus cortex or thymus medulla?
Thymus medulla
Thymus cortex Vs Medulla: which one has more lymphocytes?
Cortex
Thymus cortex Vs Medulla: Colour
Cortex: Peripheral dark staining region;
Medulla: Lighter central region
The innate immune system acts immediately when pathogens invade. (T/F)
T
Chemical barrier for entry of pathogens
Sweat and tears
Which cell is responsible for switching off the immune response, CD8+?
Suppressor T cells
How is natural killer cell different from cytotoxic T cells?
Same function, but natural killer cell lack some typical lymphocyte feature
Action of cytotoxic T cells
It secretes perforin which forms a pore in the target cell membrane
Epithelial reticular cells (EC) are thought to produce_____ and______, which promote T cell differentiation and proliferation
thymosin, thymopoetin
Hassall’s corpuscles is found in thymus _______
medulla
postcapillary venules is also known as ______
high endothelial venules
Name one mammotroph
Prolactin
Hormones stored in neurohypophysis (posterior pituitary)
Antidiuretic hormone & Oxytocin
Organs not under pituitary control
Pancreas , Adrenal medulla , Parathyroid
Role of Parafollicular cells
Secrete Calcitonin
Colloid contains ______ which is under TSH control
thyroglobulin
Role of parathyroid glands (4 tiny glands located behind thyroid gland)
Secretes parathyroid hormone which raises blood calcium levels
Are steroids stored in granules?
No. Steroids are not stored in granules and they diffuse through the plasma membrane
What does adrenal cortex synthesise?
Cholesterol/ steroid
Cells found and hormones secreted in Adrenal medulla
- (Pale staining) Chromaffin cells
– Ganglion cells
– Epinephrine and norepinephrine produced
Role of Somatostatin
suppresses release of insulin, glucagon
Role of Pancreatic polypeptide
inhibits secretion of pancreatic enzymes
