Blood & Nerves Flashcards
Bone marrow:
where is the myelon series and what does it give rise to?
- next to bone
- WBCs
Bone marrow:
where is the erythron series and what does it give rise to?
- between bony trabeculae
- erythrocytes
Bone marrow:
where are the megakaryocytes and what do they give rise to?
- between bony trabeculae
- platelets
describe erythropoiesis
- haemoglobin production increases in cytoplasm as cell matures
- loss of organelles and reduction in size
- haemoglobin concentration in cytoplasm increases (basophilic -> eosionophilic)
- loss of nucleus
what is erythropoiesis mediated by?
erythropoeitin (produced in kidney)
what is granulopoeisis?
maturation of WBCs (specifically granulocytes)
what happens during granulopoeisis?
- number of granules increases
- complexity of shape of nucleus increases
- large pool of stored mature neutrophils in bone marrow to be released into circulation during times of infection
where are erythrocytes produced and destroyed?
produced - liver (foetus) and bone marrow (adult)
destroyed - liver and spleen
describe the structure of erythrocytes
- no nucleus
- biconcave discs
- cytoplasm mainly contains haemoglobin
- cell membrane has endoskeleton attached to spectrin (protien)
what is the difference between granulocytes and agranulocytes?
granulocytes contain visible granules
what are the contents of granulocytes?
40-74% neutrophils
5% eosinophils
0.5% basophils
what is the content of agranulocytes?
20-50% lymphocytes
1-5% monocytes
what are platelets derived from?
megakaryocytes (bone marrow)
what is the function of platelets?
blood clotting
describe the structure of platelets
- cell membrane
- contain vesicles with coagulation factors
what is the function of neutrophils?
primary phagocyte
how do neutrophils move?
- circulate in blood
- invade through walls of blood vessels and into glycosaminoglycan matrix of tissues
describe the structure of neutrophils
- multi-lobed nucleus
- granular cytoplasm
- myeloperoxidase for respiratory burst (phagocytic)
what types of cytoplasmic granules do neutrophils contain?
- primary
- secondary
- tertiary
what are the primary granules in neutrophils?
lysosomes (myeloperoxidase, acid hydrolases)
what are the secondary granules in neutrophils?
secrete substances that mobilise inflammatory mediators
what are the tertiary granules in neutrophils?
- gelatinases (break down proteins)
- adhesion molecules
aid neutrophil in passage out of blood vessels and through tissue
what is the function of eosinophils?
- neutralise histamine (restrict inflammatory responses)
- inhibit mast cell secretion
- phagocytosis
describe the structure of eosinophils
- bi-lobed nucleus
- distinctive large red cytoplasmic granules with crystalline inclusions in cytoplasm
what type of receptors do eosinophils have?
IgE
describe the electron-microscopic structure of eosinophils
lozenge-shaped granules with crystalline cores
Charcot-Leyden crystals
where can Charcot-Leyden crystals be found?
eosinophils
what is the function of basophils?
- release histamine (and other vaso-active agents) in response to allergens
- prevent coagulation and agglutination
describe the structure of basophils
- bi-lobed nucleus
- prominent dark-blue staining cytoplasmic granules (histamine)
what type of receptors do basophils have?
IgE
what are the subtypes of lymphocytes?
- B cells
- T cells
what is the function of B cells?
- become plasma cells
- secrete antibodies
where do B cells develop?
bone marrow
what is the function of T cells
cell-mediated immunity
where do T cells develop?
thymus
what is the function of T-helper cells?
- help B-cells
- activate macrophages
what is the function of T-cytotoxic cells?
kill previously marked target cells
what is the function of T-suppressor cells?
suppress TH cells -> suppresses immune response
what is the function of natural killer cells?
mainly kill virus infected cells
what are the types of T cell?
- T-helper
- T-cytotoxic
- T-suppressor
- natural killer
Describe the structure of lymphocytes
- appear to be almost all nucleus
- thin cytoplasm (few organelles)
what is the function of monocytes?
- differentiation
- phagocytic and defensive role
what types of cell can monocytes differentiate into?
- tissue macrophages
- kupffer cells (liver)
- osteoclasts (bone)
- antigen presenting cells
- alveolar macrophages (lung)
describe the structure of monocytes
- kidney bean shaped nucleus
- small cytoplasmic granules (mostly lysosomes)
What are the layers of arteries (from inside -> out)?
- lumen
- endothelium
- basement membrane
- intima
- internal elastic lamina
- media
- external elastic lamina
- adventitia
what type of endothelium is found in arteries?
squamous
what is the intima?
thin layer of loose connective tissue
what is the media?
- thick connective tissue
- contains smooth muscle, some fibroblasts, variable amounts of collagen and elastin
what is the adventitia?
loose connective tissue
where are elastic arteries found?
near the heart
what is the defining factor of elastic arteries?
media contains abundant concentric sheets of elastin
where are muscular arteries found?
most arteries of the body
what are the defining factors of muscular arteries?
- media contains layers of smooth muscle and small amount of elastin
- smooth muscle cells arranged circumferentially
what are arterioles?
resistance vessels
what are the defining factors of arterioles?
- <4 muscle layers in media
- poorly developed internal elastic lamina
- normally lack external elastic lamina
what do arterioles give rise to?
capillary network
what are the layers of capillaries (from inside to out)?
- lumen
- endothelium
- basement membrane
accompanied by pericye
what are pericytes?
discontinuous layer on the outside of capillaries
- becomes continuous as capillaries grow
what is the function of pericytes?
allow constriction and relaxation of capillaries (regulates their diameter)
where can fenestrated capillaries be found?
- kidney
- liver
where do capillaries drain into?
venous system
what are fenestrated capillaries?
incomplete vascular endothelial layer
what is the function of fenestration in capillaries?
facilitates movement of materials out of circulation -> surrounding tissues
what are the layers of veins (from inside -> out)?
- lumen
- intima
- endothelium
- basement membrane
- internal elastic lamina
- media
- adventitia
which blood vessels have an external elastic lamina?
arteries
is the media thicker in arteries or veins?
arteries
what are venules associated with?
arterioles
describe the structure of venules
- thin walls
- valves
associated with pericytes
as venules become veins, what are pericytes replaced by?
media (smooth muscle)
what type of smooth muscle is found in vein walls?
circular or longitudinal
describe the structure of lymphatics
- thin walled
- valves
- lined with vascular endothelium, thin intima, media and adventitia
what is the composition of lymphocytes?
- no blood
- eosinophilic lymph (fluid derived from blood plasma)
- may contain lymphocytes
where is the cell body of peripheral nerves normally found?
ganglion
what are the connective tissue layers of myelinated peripheral nerves (inside -> out)?
- endometrium
- perineurium
- epineurium
where is the endoneurium found and what is its function?
- between individual axons
- binds individual axons together
where is the perineurium found and what is its function?
- surrounds group of axons to form fascicles
- binds axons together to form nerve fibre
where is the epineurium found and what is its function?
- binds fascicles together to form nerve fibres
what part of myelinated peripheral nerves can be seen with H&E and what colour?
myelin sheaths
- brown
what are the types of peripheral nerves?
- motor neurons
- sensory neurons
- sympathetic neurons
- parasympathetic neurons
where are the cell bodies of motor neurons located?
grey matter of spinal cord
where are the cell bodies of sensory neurons found?
dorsal root ganglion
where are the cell bodies of sympathetic neurons found?
- grey matter of spinal cord
- adjacent sympathetic ganglia
where are the cell bodies of parasympathetic neurons found?
- brain
- local ganglia of organs
what does the neuro-vascular bundle contain?
- nerve
- arteriole
- venule
what is the function of myelin?
insulates axons
what is the composition of myelin?
- spiral of Schwann cell membranes
Schwann cell envelopes and spirals around part of axon
what are the Nodes of Ranvier?
gaps between Schwann cells?
does myelin stain with H&E?
no
- use silver stain
in a myelinated axon, how many axons are related to a single Schwann cell?
1
in an unmyelinated axon, how many axons are associated with a single Schwann cell?
multiple
where can a perinuclear huff be found?
plasma cell
