Histology Flashcards
What is the composition of a cell?
80% water 15% protein 2.5% lipid 1.5% carbohydrate 1.1% inorganic
Embryonic cells have more water than old cells. T of F?
True
What makes up the cytoskeleton?
Mictofillaments
Microtubles
Intermediate fillaments
What is a microfilament?
Fine strands of actin which assemble into filaments and then dissociate (dynamic )
Fillamentous actin
What are microtubles?
Hollow
Composed of alpha and beta tubulin subunits
Can be assembled and disassembled
Initiate from a centromere and cnntain stabilising proteins
Polar- originate in the centre and radiate outwards
What are the functions of microtubules?
Cilia, flagella and mitotic spindles
Transport between membranes organelles and vesicles
Give 2 ATPases used to move things along microtubules?
Kinesin- moves things towards the periphery
Dynein- moves things towards the cell centre
What is the goli complex?
Flatterened membrane bound cicternaewith sub compartments
What is the function of the colgi complex
Vesicles arrive at the CIS face from SER/RER
Modify and pack macromolocules by adding sugar, splitting protein and sorting
Vesicles are emmitted from the TRANS face
What are intermediate fillaments?
A class of over 50 proteins wwhich bind intracellular elements to gather and to the plasma lemma
Where are the following intermediates found?
a) Neurofillaments
b) Glial fibrillary acidic proteins
c) desmin
d) Cytokeratins
e) vimentin
f) Filesin
g) lamin
a) Neurofillaments = nerve cells
b) Glial fibrillary acidic proteins = glial cells
c) desmin= muscle cells
d) Cytokeratins= Epithilial cells
e) vimentin = mesenchymal cells (connective tissue)
f) Filesin = Lens of the eye
g) lamin = nuclei of all cells
NB: can be used to identify the origins of tumours
How is the nucleus enclosed?
Nuclear envolope with an inner and outer nuclear membrane with nuclear pore
What is found between the nuclear membranes?
Perinuclear cistern which is continuous with the cistern of ER
What does the outer nuclear membrane extend to form?
ER and has ribosomes
What is contained within the nucleus?
DNA on chromosomes
WHat are the 2 types of chromosomes?
Euchromatin- DNA more dispersed and actively undergoing transcription
Heterochromatin- high condensed DNA not undergoing transcription
Where is tRNA and mRNA transcribed?
In the nucleus
Where is rRNA transcribed?
Nucleolus
What are inclusions?
Dispensable and transient
Vesicles containing components either synthesised by the cell or taken up form the ECF
What is an intercellular or occluding junction and what is its function?
Tight junction which appears as a focal region of close proximity between adjacent cell membranes
Prevent diffusion
What is a communicating junction?
Gap junction
A circular patch with hundreds of pores
Close association of cells
What forms the pores in gap junctions?
Connexion proteins
What is the function of communicating junctions?
Allow selective diffusion of molecules between adjacent cells
What are the 2 types of anchoring junctions?
Adherent junctions
Desmosomes