Histo Test 2 Stuff Flashcards
What type of immunity is performed by the lymphoid system?
Adaptive Immunity
What are the two types of adaptive immunity? Which cells (B/T) are involved with each?
Humoral–B cells
Cell mediated– T cells
Which type of immunity results in antibody production?
Humoral
A molecule that is foreign to the body is called an ____
antigen
How do B cells work?
Have surface antibodies that bind to antigens
How do T cells work?
Surface receptors that bind with antigens presented to them
Two types of lymphoid tissue arrangements?
Diffuse
Solitary nodules
What fibers constitute the framework (stroma) of lymphoid tissue?
Reticular fibers
Organs where lymphocytes are produced and/or become immunocompetent? Name 2
Primary lymphoid organs
1) thymus
2) bone marrow
Where immunocompetent lymphocytes contact antigens and proliferate? Name 2
Secondary lymphoid organs
1) lymph nodes
2) spleen
What is lymph?
Excess tissue fluid
What vessels make up the intranodal channels?
subcapsular sinus–> intermediate sinus–> medullary sinus
Describe pathway of tissue fluid through lymph node
afferent lymphatic vessels–>intranodal channels–>efferent lymphatic vessel
The lymph node is the only organ with what vessel?
AFFERENT lymphatic vessels
The lymph node capsule is composed of what?
DICT
What are the 3 layers of the lymph node? Which cell types are found in each?
1) cortex–B cells
2) Paracortex– T Cells
3) Medulla–Mixed
What specific cells are found in primary nodules that are immunocompetent but haven’t interacted with an antigen?
Naive B-lymphocytes
How do naieve B lymphocytes enter lymph node? Where do they come from?
HEVs; from bone marrow
Which cell type of lymphoid nodules is antigen presenting?
Follicular dendritic cells
What differentiates a primary from secondary nodule?
Presence of a germinal center
What happens after lymphocytes are presented with an antigen?
Become lymphoblasts and divide into plasma cells and memory cells
Which area of the lymph node is “thymus dependent”?
Paracortex
What specialized vascular structure can be found in the paracortex?
High endothelial venules (HEVs)
Which segement of the GI tract possesses Peyer’s patches?
Ileum
What two structures do peyer’s patches lack?
Capsule and afferent lymphatic vessel
What specialized cell is associated with peyer’s patches and samples antigens in the ileum’s lumen?
M cells
Does the spleen filter blood, lymph or both?
Blood
What are the two main divisions of the spleen?
White pulp and red pulp
What’s the origin of the splenic artery?
Celiac artery
Name the penicillar arteries
pulp artery, sheathed arteriole, terminal arteriole
Describe blood flow through spleen?
Splenic artery–>trabecular a–>central artery–>penicillar a–>venous sinuses–>collecting veins–>trabecular veins–>splenic vein
What type of artery is the central artery?
arteriole
Where does the first exposure of antigens to cells of immune system occur in the spleen?
Marginal zone sinuses
Which thymus lobe is absent in canines?
Cervical
When does thymus involution begin? What can accelerate it?
Puberty; corticosteroid drugs
Where do immature precursors for the thymus come from?
Bone marrow
2 main functions of the thymus
1) produce immunocompetent T-lymhpocytes
2) destroy abnormal thymocytes
When does a thymocyte become a t-lymphocyte?
After it LEAVES the thymus
Which cells form the internal stroma of thymus?
Epithelio-reticular cells
Which area of the thymus is shared btwn lobules? which is separate?
Shared: medulla
Separate: cortex
Where can the most immature thymocytes be found?
Cortex
What important structure do the ER cells form?
Blood-thymus barrier
What does the blood-thymus barrier allow the production of?
Immunocompetent, but uncommitted t-lymphocytes
Does the thymus contain lymphoid nodules?
No
What do mature thymocytes exit through?
medullary veins
Where are antigen presenting cells of the thymus? Purpose?
Cortex; assist in selection process to eliminate those that respond to self-antigens
Layers of old/degenerating reticular cells are called? Where can they be found?
Thymic corpuscle; medulla
What germinal layer does epidermis develop from? Dermis? Hypodermis?
Epidermis–ectoderm
Dermis and hypo–mesoderm
Epidermal layers from deepest to superficial?
Stratum basale, spinosum, granulosum, lucidum, corneum
Cells types found in stratum basale?
Basal cells, melanocytes, and merkel cells
Key characteristic of stratum spinosum?
numerous intercellular bridges (desmosomes)
Cell types found in stratum spinosum?
Keratinocytes, langerhans cells, melanophore
Key characteristic of stratum granulosum?
keratohyalin granules
Function of filaggrin?
assembles keratin filaments into bundles
Which epidermal layer isn’t common among domestic spp?
Stratum lucidum
Unique transformation product of keratohyalin in stratum lucidum?
Eleidin
Layer of the stratum corneum that is “flaking off”
stratum disjunctum
What do melanocytes use to produce melanin? enzyme used and what activates it?
Tyrosine; tyrosinase (activated by UV light)
membrane bound bag where melanin is synthesized?
melanosome
Keratinocytes that uptake melanin are called?
Melanophore
Function of langerhans cells?
antigen presenting
Function of merkel cell
mechanorecptor for sense of touch..closely associated with axon terminal
Function of merkel cell
mechanorecptor for sense of touch..closely associated with axon terminal
At dermo-epidermal juntion, what are teh epidermal pegs called? Dermal?
Epidermal–Rete pegs
Dermal– Dermal papillae
Primary fiber type of dermis?
Type 1 collagen
2 layers of the dermis?
Papillary layer (upper 1/3) Reticular layer (lower 2/3)
Function of hypodermis?
attaches dermis to deep fascia
Function of hypodermis?
attaches dermis to deep fascia
3 networks that make up the dermal blood supply? general location?
superficial (close to epidermis)
middle (near follicles and glands)
deep (junction of dermis and hypodermis)
What are the regions of the hair proper?
shaft and root
stem cells that proliferate to form the hair?
Matrix
Layers of the hair proper?
cuticle, cortex, medulla
In which direction do the free edges of the cuticle point? what layer do they interlock with?
upward; cuticle of IRS
Which layer of the hair follicle doesn’t span the entire length? Where does it end?
IRS; where sebaceous glands empty into follicle
Which layer is continuous with the epidermis?
ERS
What structure provides vascular nourishment for hair growth?
Dermal papilla
What type of muscle is the arrector pili?
smooth
What composes the pilosebaceous unit?
hair proper, hair follicle, arrector pili, sebaceous gland
What are the 3 phases of the hair cycle?
Anagen, catagen, telogen
What forms during catagen when the bulb detaches?
club hair
What structure is modified into 2 layers in the tactile hair? Name layers
dermal sheath
1) inner dermal sheath
2) outer dermal sheath
What unique structure separates the 2 dermal sheath layers of a tactile hair?
Follicular blood sinus
Name 3 stimuli and the mechanoreceptors they activate
1) free nerve endings–light touch
2) merkel cells–touch pressure
3) vibration–pacinian corpuscles
Where do the sebaceous glands open? mode of secretion? nature of secretion?
into upper 1/3 of follicle; holocrine secretion; sebum (lipid)
Two types of sweat glands? which are most common? where does each open?
1) Apocrine (COMMON)–opens into hair follicle
2) Merocrine–opens onto epidermal surface
