Histology: Blood and Blood Vessels Flashcards
what are the 3 layers of blood vessels (inner to outer)
- tunica intima
- tunica media
- tunica adventitia
describe the tunica intima
single squamous endothelium supported by a basal lamina
describe the tunica media
smooth muscle of varying thickness
describe the tunica adventitia
supporting connective tissue
what separates the 3 layers of blood vessels
internal and external elastic membranes
what are elastic arteries and why is this the case
- larger arteries where the tunica medias smooth muscle is replaced by elastic tissue
- allows for greater elastic recoil
what is Verhoeff’s/Masson Trichome stain
- elastic fibres, black
- collagen, green
- smooth muscle, red
what are vaso vasorum
blood supply to vaso vasorum
describe the layers in an arteriole
- smaller tunica media and therefore less smooth muscle
- almost no adventitia
- control blood flow to tissues
what are capilaries composed of and what are the 3 types
- endothelial cells and basal lamina
- continuous
- fenestrated
- discontinuous
describe a continuous capillary and where its typically found
- continuous
- muscle, nerve, lung, skin
describe a fenestrated capillary and where its typically found
- has small pores
- gut mucosa, endocrine glands, kidney
describe a discontinuous capillary and where its typically found
- has large pores
- liver, spleen, bone marrow
what is the function of pre-capillary sphincters and what are the composed of
- control blood flow through the network
- smooth muscle
describe the path blood takes through the microvasculature
small arteriole -> meta-arteriole -> pre-capillary sphincter -> capillary -> thouroughfare channle -> post-capillary venules
describe the compositin of venules
endothelial cells and thin connective tissue layer
venules are important sites of what
exchange, i.e. inflammation
when are blood vessels classified as venules
when their tunica media has intermittent smooth muscle
when are blood vessels classed as veins
when they have a tunica intima, continuous tunica media and tunica adventitia
what is the tunica adventitia like on the largest veins
thick with longitudinal smooth muscle
what are valves and what is their purpose
inward extensions of the endothelium, prevent backflow of blood
give an overview of blood flow form elastic arteries to large veins
elastic arteries -> arterioles -> small arteriole -> metarteriole -> pre-capillary sphincter -> capillary -> post capillary venule -> venules -> small veins -> big veins
describe the vessels of the lymphatic system and its function
system of thin-walled vessels that transport lymph to lymph nodes for immune surveillance and drains excess lymph from tissues into blood stream
how does the lymphatic system produce flow
- skeletal muscle pump
- smooth muscle in vessel walls
- hydrostatic pressure in tissue
- valves
what are the formed component of blood
- plateltes
- WBCs
- RBCs
what are the 2 main categories of WBCs
- granulocytes
- agranulocytes
what type of cells are granulocytes
- mast cells
- eosinophils
- neutrophiols
- basophils
what type of cells are agranulocytes
- monocytes
- lymphocytes
monocytes
- macrophages
- dendritic cells
what type of cells are lymphocytes
- T cell
- B cell
- NK cell
what is used to separate blood and how does its separate
- centrifuge
- RBCs on bottom -> WBCs -> plasma (densest - less dense)
how is serum obtained
blood allowed to clot, clot remove and blood is then spun on centrifuge
describe RBCs
bi concave, no nucleus, contain Hb and can deform to slip through small spaces
how can RBCs slip through small spaces
contain a netwokr of flexible cytoskeleton elements
how long do RBCs circulate and what removes them
- 4 months
- liver and spleen
where is the majority of blood
peripheral veins
describe neutrophils
- stains poorly
- promient, multi-lobed nucleus
- abundant and short lived
what produces neutrophils
bone marrow
describe the activation of neutrophils
circulate inactive and are stimulated by phagocyte/inflammation/etc, the enter the tissue and become phagocytotic
describe eosinophils
- stain red (with eosin)
- circulate and then move into tissue
- bigger than neutrophils and contain a bilobed nucleus
- granules contain hydrolytic enzymes
function of eosinophils
- induce and maintain inflammation in allergic reactions and asthma
- fight parasitic infections
describe basophils
- stain blue/purple with basic dyes
- bilobed nucleus often obscured by granules
- granules contain inflammatory mediators
how do basophiles function
- effector in allergic reactions
- have high affinity for IgE and and react to a specific allergen
- degranulates when antigen binds
- lead to hayfever, asthma, allergic reactions, etc
describe monocytes
- macrophage precursor
- small lysosomal granules
- biggest
- kidney bean shaped nucleus
where are macrophages found
mainly connective tissue but some are ‘wanderers’
where are (macrophages)
- Kuppfer cells
- Microglia
- Langerhans cells found
- liver
- brain
- skin
describe lymphocytes
- round nucleus surrounded by a thin cytoplasm
- no granules
- arise from bone marrow
describe T cells and their function
- differentiate in thymus
- form complex set of cells that perform defense functions
describe B cells function
- give rise to antobidy secreting plasma cells
describe platelets
- small cell fragments
- found in large numbers
- no nucleus but some organelles
- granules
- cytoskeleton
function of cytoskeleton and granules in platelets
- extrusion of granules and clotting factors
- granules include coagulation factors
where is the earliest site of erythrocyte formation and where does it occur a little later
- outside the embryo in the yold sac at 3 weeks
- liver and spleen
where does haemopeosis occur during
- 2nd trimester
- by birth
- liver
- bone marrow
why does some bone marrow stop producing erythrocytes and which one maintain it
- as bones grow excess haemopoeisis happens so theyre not needed
- pelvis, proximal femurs, ribs, skull, vertebrae
what happens to the bone marrow that stops producing erythrocytes
- become adipose tissue
- convert to RBC formation in emergency
