Histology Flashcards
describe the structure of the plasmalemma
bimolecular layer of amphipathic phospholipid molecules with hydrophilic heads and hydrophobic tails.
what substances can diffuse across the plasmalemma
small, hydrophobic, uncharged molecules
what cannot diffuse across the plasmalemma
charged molecules
define inclusions
components synthesised by the cell itself
role of the cytoskeleton
provide structural support
three classes of filaments in the cytoskeleton
- microfilaments
- intermediate filaments
- microtubules
describe the structure of microtubules
made up of two subunits- alpha and beta tubulin
two proteins involved in microtubules
kinesin is an ATPase that moves to the cell periphery
dyne is an ATPase that moves towards the cell centre
describe the structure of the nucleus
nuclear envelope comprises of an inner and outer membrane with a perinuclear cistern. It contains chromosomes.
two types of DNA in the nucleus
- euchromatin- dispersed DNA actively undergoing transcription
- heterochromatin- condensed DNA not undergoing transcription
structure of a ribosome
small subunit (binds RNA) and large subunit (forms peptide bonds)
define polysome
cluster of ribosomes held together by RNA. Makes unpackaged proteins.
describe how ER is involved in protein synthesis
free ribosomes attach to mRNA. If ER signal peptide is present the growing peptide is inserted into the pore of ER.
functions of SER
stores, synthesises proteins and lipids
describe the structure of the Golgi apparatus
flattened, membrane-bound cisternae with vesicles.
function of the Golgi apparatus
adds sugars and sorts
structure of mitochondria
double membrane that is extensively folded to form cristae. It contains its own DNA
function of mitochondria
produce ATP
three types of intercellular junctions
- occluding (tight)
- desmosomes (anchoring)
- communicating (gap)
function of tight junctions
diffusion barrier
function of desmosomes
strength
function of gap junctions
allows movement between cells
define a junctional complex
close association of several types of junctions
three ways material can cross the cell membrane
- diffusion
- transport proteins (pumps/ channels)
- vesicular transport (endocytosis and phagocytosis)
describe endocytosis
membrane fuses to form an endocytotic vesicle
describe phagocytosis
engulfed to form a phagosome, lysosomes release lysozyme to form a phagolysosome.
describe the histological technique for a microscope slide
- dehydrate tissue
- impregnate wax
- thin sections cut on a microtome
- wax washed out and tissue rehydrated
there are potential for artefacts
the most common combinations of staining dyes are?
- haematoxylin- basic dye with affinity for acidic molecules (purple)
- eosin- acidic dye with affinity for basic molecules (pink/red)
four basic tissue types
- epithelium
- connective tissue
- nervous tissue
- muscle
describe the structure of epithelia
lines the surfaces of organs. all have a basal lamina where cells attach. non-vascular. apical and basal end
functions of epithelia
mechanical and chemical barrier, absorption, secretion, containment and locomotion
four ways epithelia can be classified
- cell shape
- layers
- cell surface
- presence of specialised cells
describe the different cell shapes of epithelia
- squamous (flattened)
- cuboidal (cube-shaped)
- columnar
describe the different layers epithelia can have
- simple (one layer)
- stratified (2 or more)
- pseudo stratified (multiple that are all attached to the basal lamina)
describe the different cell surfaces epithelia can have
- microvilli
- cilia
- presence of keratin proteins
which two types of glands does the glandular epithelium use for secretion
- endocrine
- exocrine
three categories of connective tissue
- soft
- hard
- blood and lymph
describe the structure of connective tissue
consists of an extracellular matrix (fibres, ground substance, tissue fluid) and cells (fibroblasts, adipose, osteocytes and chondrocytes)
two types of soft CT
- loose
- dense
three types of hard CT
- hyaline
- elastic
- fibrocartilage
three types of muscle cells
- smooth
- cardiac
- skeletal
structure of smooth muscle
smooth, no striations
structure of cardiac muscle
involuntary with striations and intercalated discs
structure of skeletal muscle
striations and sacrolemmas
structure of nervous tissue
neurones and support cells (glia)
lining of neurones in CNS
meninges
lining of neurones in PNS
epineurium
three types of neurons
- multipolar
- bipolar
- pseudo unipolar
glia of the CNS
astrocytes, oligodenrocytes and microglia
glia of the PNS
Schwann cells
three basic layers in blood vessels
- tunica intima
- tunica media
- tunica adventitia
what is the tunica intima made up of
squamous epithelium and thin layer of connective tissue
what is the tunica media made up of
smooth muscle
what is the tunica adventitia made up of
connective tissue
difference in large arteries tunica media
smooth muscle is partially replaced with elastic fibres called elastic arteries for elastic recoil
structure of arterioles
one or two layers of smooth muscle and almost no adventitia
structure of capillaries
endothelial cells and a basal lamina
three types of capillaries
- continuous
- fenestrated
- discontinuous
structure of venules
thin layer of connective tissue and smooth muscle and endothelial cell lined
structure of veins
obvious tunica adventitia and valves
define serum
blood without clotting factors
three types of formed elements in the blood
- erythrocytes
- leukocytes
- platelets
define hemopoiesis
production of blood cells and platelets in the bone marrow
structure of a multipolar neuron
many dendrites, one axon
structure of a bipolar neuron
one dendrite, one axon
structure of a pseudo unipolar neuron
axon in both directions