Histology Test 3
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What kind of lymphocytes would you find in the thymus?
What is the largest organ in the body?
Diffuse lymphoid tissue
Name the APCs of the lymphoid system
- 1. Macrophages
- 2. Dendritic cells
- 3. Langerhan cells
- 4. M cells
- 5. B cells
- 6. Follicular dendritic cells
What type of lymphocytes predominate in the blood?
- T lymphocytes
- (B lymphoctyes are found in blood too, but most are T-lymphocytes)
In which areas of the lymphoid system can you find macrophages?
- Bone marrow
- Lymph nodes
- (NOT IN BLOOD)
What kind of lymphocytes does the bone marrow produce?
B lymphocytes and NK cells
Name each type of cell involved in the immune system
- 1. Lymphocytes
- 2. Supporting cells
- 3. Antigen-presenting cells
- 4. Blood granulocytes
What blood granulocytes are involved in the immune response?
What type of immune response is a cytotoxic T-cell involved in?
Adaptive immune response
What type of immune response is an NK cell involved in?
Innate immune response
What is the main function of a B lymphocyte?
- Carries IgM membrane receptors
- Differentiates into plasma cells when activated by antigens
What is the main function of a memory B-lymphocyte?
Activated B cell that is primed to responed more readily to subsequent exposure to the same antigen
What is the main function of a T-cytotoxic lymphocyte?
- Carries TCRs
- Recognizes MHC I
- Produces Perforins and other proteins that kill other cells
What is the main function of a T-helper lymphocyte?
- Carries TCR
- Stimulates activation of other T cells and B cells
What are the main functions of T-memory lymphocytes?
- Carries TCRs
- Primed to respond more readily to subsequent exposure to same antigen
What are the main functions of NK cells?
- Lacks T and B cell receptors
- Attacks virus infected cells and tumor cells without previous exposure
What are gamma/ delta T-lymphocytes and where are they found?
- They have no CD4 or CD8 markers
- They develop in Thymus and migrate to various epithelial tissues
- They do not recirculate between blood and lymphatic organs
- Function as the first line of defense
Where are CD3 markers found?
On the surface of all T-cells
What are the functions of CD3 cells?
Forms complex with TCR and activates T cell
Where are CD4 markers found?
The cell surface of T-helper cells
What is the target cell of CD4 markers?
MHC II on antigen presenting cells
What are the functions of CD 4 markers?
Activates T-helper cells
Where are CD8 markers found?
The cell surface of cytotoxic T-helper cells and Suppressor T cells
What is the target cell of CD8 markers?
MHC I on antigen presenting cells
What are the functions of CD8 markers?
activates cytotoxic T-cells
Where are CD28 markers found?
The cell surface of T-helper cells
What is the target cell of CD28 markers?
B7 on antigen presenting cells
What are the functions of CD28 markers?
Assists in activation of T-helper cells
Where are CD40 markers found?
The cell surface of B-cells
What are the target cells of CD40 markers?
CD40 receptor molecules on activated helper T-cells
What are the functions of CD40 markers?
Permits T helper cell to activate B cell to proliferate into B memory cells and plasma cells
Where are TCRs located?
The surface of T-lymphocytes
What do TCRs do?
They interact with CD markers and when they bind to MHC they trigger a cascade of events
What do MHC I molecules do?
- On all cells in body
- Decided whether something is self or non-self
- present peptides for recognition by CD8+ T cells
- Act as targets for cellular elimination
What do MHC II cells do?
- Expressed only on antigen presenting cells
- (Macrophages, dendritic cells, reticular cells)
- Present foreign peptides to CD4+ lymphocytes
N terminus of an immunoglobin contains
- antigen-binding region
- Fab domain
C terminud of an immunoglobin contains
- cell-binding domains
- Fc domain
Location of IgAs
- In body secretions and reproductive system of females
- Bound to B-cells
Function of IgAs
- Defense against proliferation of microorganisms
- Helps defend against microbes
Location of IgDs
B-cells (on the surface of mature B-lymphocytes)
Function of IgDs
Act as antigen receptors (together with IgMs)
Location of IgE
On mast cells and basophils
Function of IgEs
- Stimulates mast cells to release histamine, heparin, leukotrienes, etc
- Responsible for anaphaletic hyperactivity
Location of IgGs
- Does not have to be bound to a cell
- If it is bound to a cell it is bound to:
- Macrophage, B-cell, NK cell, neutrophil, eosinophil
Functions of IgG
- Secondary immune response
- Oponisizing pathogens
- Activate NK cells
- Crosses the placental barrier
Location of IgM
- Does not have to be bound
- B-cells (when bound)
Functions of IgM
- Most efficient in binding antigens
- (decavalent instead of bivalent when in free solution)
- Activates macrophages
- Antigen receptor of B-lymphocytes
Binding of IgM
- When free in solution it is pentemeric
- When bound to a membrane it is dimeric
How long does the primary adaptive response take?
Take about 2 weeks to form antibodies from the time the antigen is introduced
How long does the secondary adaptive response take?
Takes about 7-10 days for the body to be able to fight off the antigen or bacterial infection
What Immunoglobin is most commonly found in blood?
What does the humoral response of the adaptive immune system do?
Produces soluable Immunoglobins and memory cells
What does the cell-mediated response of the adaptive immune system involve?
Cytotoxic targeting and memory cells
What proteins are involved in B-lymphocyte activation?
- MHC II
- CD 3, CD4 and CD40 markers
- ILs 2, 4, 5 and 6
What proteins are involved in T-lymphocyte activation?
- MHC I
- CD 3 CD4 and CD8
- IL 2
Which lymphatic organs have a cortex and a medulla?
Thymus and Lymph nodes
Which lymphatic organs have lymphoid nodules?
- Peyer's patches
- Lymph nodes
Which lymphatic organs have a capsule?
- Lymph nodes
- Tonsil (partial capsule)
Which lymphatic organs have cords and sinuses?
What lymphatic organs have high endothelial veins?
- Peyer's patches
- Tonsils and Lymph nodes
What is a unique characteristic of the thymus?
What is a unique characteristic of Peyer's patches?
located only in the wall of the ileum
What are unique characteristics of lymph nodes?
cortical nodules and subscapular sinus
What are unique characteristics of the spleen?
Central artieries and red pulp
What type of lymphocytes are found in germinal centers?
What happens in germinal centers?
- Clonal proliferation of activated B lymphocytes
- They will leave GC to form plasma cells elsewhere
What are M cells?
Follicular associtated epithelium
Two items you will NOT find in the thymus
- B lymphocytes
- Germinal centers
Where does T-cell education and selection occur?
In the cortex of the thymus
What provides the structural meshwork of the thymus?
Epthelial reticular cells
What do epithelial reticular cells do?
- Expose MHCs to differentiating T-cells
- Help form the blood-thymus barrier
- Lobulate the tissue (along with the CT septa [Se]).
What eliminates T-cells that do not "pass insepection"?
What are Hassal's corpuscules?
Whorls of epithelial reticular cells
Where are Hassal's corpuscle's located?
In the medulla of the thymus
What kind of epithelium would you find on the apical side of a tonsil?
Where are germinal centers in the lymph node found?
What kind of fibers provide structural support of the lymphoid organs?
- Reticular fibers
- Type III collagen
Where do lymphocytes re-enter the lymphatic efferent system?
What are high endothelial venules?
Post capillary venules in lymph nodes that facillitate extravasation of lymphocytes from the blood to the parenchyma of the lymph node
What proteins mediate lymphocyte passage in HEVs?
Where are venous sinuses?
In the red pulp of the spleen
What does the pineal gland secrete?
What does the parathyroid gland secrete?
What do the pancreatic islets secrete?
Insulin and glucagon
What does the hypothalmus produce?
What does the anterior lobe of the pituitary gland secrete?
- Follicle stimulationf Hormone (FSH)
- Thyroid Stimulationg Hormone (TSH)
- Prolactin (PRL)
- Growth Hormone (GH)
- Lutenizing Hormone (LH)
What does the posterior lobe of the pituitary gland secrete?
RELEASE of oxytocin and ADH
What does the thyroid gland secrete?
- Thyroxine (T4)
- Triiodothyronine (T3)
- Calcitonin (CT)
What does the suprarenal medulla secrete?
What does the suprarenal cortex secrete?
What are the three molecular types hormones can come in?
- Amino acid derivatives
- Peptide hormones
- Lipid derivatives:
- steroids and eicosanoids
What are hormones that are derivatives of tyrosine?
What are catecholamines?
- Derivatives of tyrosine (amino acid hormones)
What hormone is a derivative of tryptophan?
What hormones are amino acid derivatives?
What hormones are glycoproteins?
What hormones are short polypeptides or small proteins?
- ADH, Oxytocin
- ACTH, GH, PRL, MSH
- Insulin, glucagon
What are the categories of peptide hormones?
Glycoproteins, small proteins and polypeptides
What are the types of lipid hormones?
What are eicosanoids?
Lipid derivatives of arachidonic acid
What hormones are steroid hormones?
What is the principal of amplification?
The ability of a response to trigger many second messengers to amplify the effect of a hormone
How are hormones and cytoplasmic second messengers linked?
What are G-proteins
Membrane bound enzyme complex that binds GTP
What are three types of endorcrine system reflexes?
- 1. Humoral stimuli
- 2. Hormonal stimuli
- 3. Neural stimuli
What does a humoral stimuli do?
Changes the content of the extracellular fluid
What does a hormonal stimuli mean?
The right hormone arrives on the scene
What is a neural stimuli?
The right neurotransmitter shows up at correct sites
What organs use a simple endocrine reflex system?
Heart, pancreas, parathyroid glands and digestive tract
What is a simple endocrine reflex?
Involves only one hormone and endocrine cells respond directly to changes in the extracellular fluid
What are the functions of the hypothalmus?
- 1. Secrete regulatory hormones to control adenohypophysis
- 2. Production of ADH and oxytocin
- 3. Control of sympathetic output to suprarenal medulla
What makes the hypothalmo-hypopohysial structurally different from the regular blood system?
It goes from capillaries to veins to capillaries for hormonal release
What does the hypothalmohypophysial portal system accomplish?
Gets the releasing hormones to their target without dilution
What does growth hormone releasing hormone (GHRH) do?
Stimulates secretion and gene expression of GH by somatotropes
What does somatostatin do?
Inhibits secretion of GH by somatotropes
What does dopamine do?
inhibits secretion of PRL by lactotropes
What does corticotropin releasing hormone (CRH) do?
- Stimulates secretion of ACTH by corticotropes
- Stimulates gene expression for POMC in corticotropes
What does gonadotropin releasing hormone (GnRH) do?
Stimulates secretion of LH and FSH by gonadotropes
What does thyrotropin releasing hormone (TRH) do?
- Stimulates secretion and gene expression of TSH by thyrotropes
- Stimulates secretion and synthesis of PRL
- Antidiruetic hormone
- Synthesized by the hypthalmus
- Released by the neurohypohysis
- Target cell are the kidneys
What does the hypothalmohyppophysial tract do/ contain?
- Transports oxytocin and ADH to the pars nervosa
- contains unmyelinated axons of neurosecretory cells
What are Herring bodies?
Granules in the pars nervosa that contain neurosecretory accumulations
What are the supporting cells of the pars nervosa?
What are the two types of cells in the parathyroid gland?
Chief cells and oxyphil cells
What do chief glands produce?
What does parathyroid hormone do?
Raises blood calcium levels by stimulating osteoclasts to resorb bone
What are the three layers of the adrenal cortex?
- 1. Zona glomerulosa
- 2. Zona fasciculata
- 3. Zona reticularis
What is produced in the zona glomerulosa?
What is produced in the zona fasciculata?
- (cortisol and corticosterone)
What is produced in the zona reticularis?
What stimulates hormone production of the adrenal cortex?
What are the two types of cells found in the adrenal medulla?
- 1. Chromaffin cells
- 2. Sympathetic ganglion
What do Chromaffin cells do?
Synthesize, store and secrete epinephrine and norepinephrine
What stimulates the release of catecholamines?
Intense emotional stimuli and is mediated by preganglionic sympathetic fibers
What kind of epithelium is germinal epithelium covering the ovaries?
simple cuboidal epithelium
Primordial follicles are composed of...
a primary oocyte with a single layer of flat follicular cells
Primary follicles are composed of...
Primary oocyte with surrounding zona pellucida
Multilayer follicular cells contain...
several layers of follicular cells known as granulosa cells and a theca layer
Graffian follicle contains
antrum that is completely filled with liquor folliculi and cumulus oophorus
Graffian follicles secretes...
Inhibin to shut off other developing follicles
- In a graffian follicle
- Small mound of granulosa cells that project into the antrum
Theca interna cells manufacture...
androgens which are transferred to granulosa cells and converted to estrogen
Where are androgens secreted by the theca interna turned into estrogen?
What is the remnant of the corpus luteum called?
The corpus luteum produces
What does progesterone do?
- Promotes the development of endometrium
- Inhibits the release of LH by supressing the LHRH
What does Gonadotropin releasing hormone do?
Stimulates secretion of LH and FSH
What does FSH do?
Stimulates the growth and development of seconday ovarian follicles and the appearence
LH surge does what?
- promotes formation of corpus luteum
- triggers ovulation of seconday oocyte
In the absense of pregnancy which hormones are not present?
- HCG and LH
- Corpus luteum will atrophy
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