Histology Flashcards
Where do inclusions come from?
synthesised by the cell itself or are taken up from the extracellular environment
What is the cytoskeleton made up of?
- microfilaments (actin)
- intermediate filaments (6 main proteins)
- microtubules (two tubular proteins)
What are the features of microtubules?
polar
dynein and kinesin to drag organelles
In what directions do dynein and kinesin pull organelles?
dynein pulls to cell centre
kinesin pulls to cell periphery
What is the perinuclear cistern?
the space between the inner and outer membrane
What are the features of euchromatin and heterochromatin?
euchromatin is more dispersed and actively undergoes transcription
heterochromatin is highly condensed and is not undergoing transcription
What is the role of the small subunit of the ribosome?
binds RNA
What is the role of the large subunit of the ribosome?
formation of peptide bonds
What is the function of the Golgi?
adds sugars
cleaves proteins
sorts into vesicles
What are the three types of cell junctions?
occluding
anchoring
communicating
What are the features of an occluding junction?
prevent diffusion
aka tight/zonula occulens
What are the features of an anchoring junction?
bind in extracellular space by actin link molecules
aka zonula adherens
desmosomes
What are the features of desmosomes?
type of anchoring junction
aka macula adherens
provide mechanical stability
What are the features of a communicating junction?
selective diffusion
pores
spread of excitation
aka gap junction
How is a specimen prepared?
fixed with formalin
thinly sliced
impregnate with wax
to make artefact
What colours are eosin and haematoxylin?
eosin is pink
haemotoxylin is purple
What are the four tissue types?
- epithelium
- connective tissue
- muscle
- nervous tissue
What are the features of epithelium?
basal lamina
non-vascular
polarised
forms glands and covers body surfaces
What are the roles of epithelia?
barrier absorption secretion containment movement
What are the features of covering epithelia?
classified by cell shape/ number of layers/ cell surface/ presence of special cells
What are the types of glandular epithelia?
endocrine
exocrine
What are the features of endocrine glandular epithelia?
product is secreted to basal end
ductless
What are the features of exocrine glandular epithelia?
product is secreted to lumen end onto body surface or into a duct
ducted
What are the types of connective tissue?
soft
hard
blood and lymph
What are the features of connective tissue?
extracellular matrix so fibres, ground substance and tissue fluid
cells include fibroblasts, adipose cells, osteocytes and chondrocytes
What are the types of hard connective tissue?
hyaline
elastic
fibrocartilage
(cartilage is avascular and semi-rigid)
What are the two types of bone and where are they located?
cortical bone in the diaphysis
cancellous bone in the epiphyses
What are the types of muscle?
smooth (involuntary, visceral, cigar-shaped nucleus)
skeletal (voluntary, striated, multi-nucleated, nuclei on periphery)
cardiac (striated, intercalated discs, single nucleus)
What are the three types of neurons?
multipolar
bipolar
pseudounipolar
What are the principle glia of the CNS?
astrocytes (support, ion transports, induce BBB)
oligodendrocytes (produce myelin in the brain and spinal cord)
microglia (immune surveillance)
What does nervous tissue consist of?
neurons support cells (glia)
What is the coat made up of in nervous tissue in CNS or PNS?
meninges for CNS
epineurium for PNS
What is the principle glia of the PNS?
Schwaan cells
What are the three main silvery glands?
parotid
submandibular
sublingual
What do striated ducts in the salivary glands do?
pump out saliva
What are the layers of the digestive tract?
- mucosa epithelium (on basal lamina) lamina propria (loose connective tissue) muscularis mucosae (thin layer of smooth muscle) - submucosa (loose connective tissue) - muscularis externae - adventitia
What are the usual jobs of the cells in the mucosa?
- absorptive
- protective
- absorptive and protective
- secretory
What is the enteric nervous system for?
the digestive tract
Where do the ganglia for the enteric nervous system lie?
between two muscle layers in the muscularis externa
What is the basic structure of the liver?
lobules with hepatic artery and portal vein at each corner that drain tot he central vein in the middle
What is the function of the pancreas?
- exocrine produces proteases, lipases, nucleases which all enter duodenum by pancreatic duct
- endocrine is islets of langerhans which produce insulin
What are the three layers of a normal blood vessel?
- tunica intima (endothelial cells, basal lamina and connective tissue)
- tunica media (smooth muscle)
- tunica adventitia (connective tissue)
Where are the internal and external elastic membranes?
internal is between intima and media
external is between media and adventitia
What is the structure of elastic arteries?
large elastic tunica media
What is the vast vasorum?
the specialised blood supply for large elastic arteries when the wall is too thick to get nutrients from the lumen
What is the structure of arterioles?
thin media
almost no adventitia
What is the structure of capillaries?
endothelial cells and basal lamina
What are the types of capillaries?
continuous (no gaps)
fenestrated (small pores)
discontinuous/ sinusoidal (large gaps)
What is the structure of venules?
endothelial cells and thin connective tissue
intermittent smooth muscle in media
What is the structure of veins?
large adventitia
thin media with smooth muscle
valves are extensions of intima
What do the lymph vessels do and what is their structure?
carry lymph to lymph nodes for immune surveillance
smooth muscle in walls
voluntary muscle controls flow and valves
What are the two classes of white cells?
- granulocytes neutrophils eosinophils basophils - agranulocytes lymphocytes monocytes
What are the features of neutrophils?
multi-lobed nucleus
phagocytes
common
What are the features of eosinophils?
bilobed nucleus
allergic reactions
What are the features of basophils?
rare
bilobed nucleus
large granules
IgE on cell membrane
What are the features of lymphocytes?
B cells are plasma cells
T cells have defence functions
What are the features of erythrocytes?
no nucleus no organelles flexible cytoskeleton to slip through gaps haemoglobin biconcave
What are the features of platelets?
haemostasis
no nucleus
cytoskeleton
granules e.g. coagulation factors
Where are red blood cells made in embryology?
yolk sac at 3 weeks
spleen
liver
What are megakaryotes?
bone marrow cells producing platelets
What cells can carry out haemopoiesis in the mature skeleton?
vertebrae ribs skull pelvis proximal femurs
