Histology Flashcards
1
Q
Features common to all Eukaryotic Cells
A
- Outer membrane
- inner cytosol
- Cytoskeleton
- Organelles
- Inclusions
2
Q
What is the role of the plasma membrane?
A
separates the cytoplasm from the outside environment
3
Q
Definition of the plasma membrane
A
a bimolecular layer of amphipathic phospholipid molecules with their hydrophilic heads at the outer and inner surfaces and their hydrophobic fatty acid tails facing the middle of the 2 layers
4
Q
Contents of the plasma membrane
A
- phospholipid molecules
- integral proteins
- cholesterol
- carbohydrates
5
Q
role of integral proteins in the plasma membrane
A
They can act as receptors, channels, transporters, enzymes and cell attachment proteins
6
Q
movement of material inside the cell to extracellular environments
A
exocytosis
7
Q
movement of material outside the cell into the cell
A
endocytosis
8
Q
Permeability of the plasma membrane
A
HIGHLY permeable to:
-water
-oxygen
-small hydrophobic molecules
VIRTUALLY IMpermeable to:
charged ions i.e. Na+
9
Q
The cell membrane is fluid TRUE/FALSE
A
TRUE
10
Q
intracellular
A
within the cell
11
Q
intercellular
A
between cells
12
Q
contents of the cytoplasm
A
organelles
inclusions
13
Q
Organelles within the cytoplasm (6)
A
Mitochondria
Rough endoplasmic reticulum
Smooth endoplasmic reticulum
Golgi apparatus
lysosomes
nucleus
14
Q
Inclusions
A
components that the cell has synthesised itself or taken up from the extracellular environment
{may or may not be bound by a membrane}
15
Q
what are the 3 types of cytoskeletal filaments
A
microfilaments
intermediate filaments
microtubules
16
Q
diameter of microfilaments
A
7nm
17
Q
what are microfilaments composed of?
A
actin protein
18
Q
diameter of intermediate filaments
A
> 10 nm
19
Q
what are intermediate filaments composed of?
A
6 main proteins which vary in different cell types
20
Q
diameter of microtubules
A
25 nm
21
Q
what are microtubules composed of?
A
2 types of tubulin subunit (alpha and beta)
22
Q
structure of microtubules
A
a hollow alternating array of alpha and beta tubulin and can be assembled and disassembled
include stabilising proteins (microtubule associated proteins MAPS)
23
Q
where do microtubules originate from?
A
the centrosome
24
Q
role of dynein and kinesin with microtubules
A
the proteins attach to the microtubules and move along them, whilst associating with the membranes of organelles and vesicles ‘dragging’ them along the microtubule.
25
Kinesin is an ATPase that moves toward the cell centre. TRUE/FALSE
FALSE Kinesin travels towards the cell periphery
26
Dynein is an ATPase that moves towards the cell centre TRUE/FALSE
TRUE
27
what are cilia?
hairlike projections important in the movement of substances
28
how can intermediate filaments be used to identify tumour origins?
The filaments are separated into classes and so the type of filament will correspond with a location or cell type.
29
location of neurofilaments
nerve cells
30
Glial fibrillary acidic proteins are present in the glial cells of the nervous system. TRUE/FALSE
TRUE
31
Intermediate filaments located in muscle cells
desmin
32
location of cytokeratins
epithelial cells
33
mesenchymal cells contain filesin. TRUE/FALSE
FLASE.
mesenchymal cells contain VIMENTIN
34
intermediate filament associated with the lens of the eye cells
filesin
35
location of lamin filaments
nuclei of all cells
36
role of intermediate filaments
bind intracellular elements together and to the plasma membrane
{form a network throughout the cells cytoplasm}
37
what is the structure of the nucleus?
- enclosed by a nuclear envelope
- inner and outer nuclear membrane
- nuclear pores providing continuity with the cytoplasm
- contains chromosomes
38
the outer nuclear membrane is studded with ribosomes. TRUE/FALSE
TRUE.
The outer nuclear membrane is also continuous with the rough endoplasmic reticulum within the cytoplasm
39
site of transcription of mRNA
nucleus
40
site of transcription of tRNA
nucleus
41
site of rRNA transcription
nucleolus
42
what are the 2 types of DNA contained within the nucleus?
euchromatin and heterochromatin
43
what is euchromatin?
DNA that is more dispersed and is actively undergoing transcription
44
what is heterochromatin?
DNA that is highly condensed and is not undergoing transcription
45
how are chromosomes arranged in euchromatin?
uncoiled (active)
46
how are chromosomes arranged in heterochromatin?
coiled (inactive)
47
the nucleus is surrounded by a [SINGLE/DOUBLE] nuclear membrane
DOUBLE
48
where are ribosomes formed?
the nucleolus
49
what are ribosomes made up of?
a small subunit and a large subunit
50
what is the role of the small subunit within a ribosome?
binding RNA
51
What is the role of the large subunit within a ribosome?
catalysing the formation of peptide bonds
52
what is the structural difference between the smooth and rough endoplasmic reticulum?
the rough endoplasmic reticulum is 'studded' with ribosomes
53
what is the role of the rough endoplasmic reticulum?
a vital role in the synthesis of proteins destined for insertion into membranes or for secretion
54
how does the amount of different types of ER vary between cell types?
cells that are relatively metabolically inactive have relatively little ER.
55
what is the role of the smooth endoplasmic reticulum?
continuing the processing of proteins produced in the RER
the site of lipid synthesis.
56
Is the amount of SER and RER the same in all cells?
NO.
most cells have relatively little SER but some specialised cells have an extensive amount
57
structure of the Golgi apparatus
a group of flattened, membrane bound cisternae arranged in sub-compartments
58
Role of the Golgi apparatus
modification and packaging of macromolecules produced in the ER.
-adds sugars
-cleaves some proteins
-sorts macromolecules into vesicles
59
Mitochondria can be easily seen in normal staining. TRUE/FALSE
FALSE
mitochondria cannot be seen easily in normal staining
60
what are mitochondria?
oblong, cylindrical organelles, typically 0.5-2 micrometers in length.
61
structure of the mitochondria
- in outer membrane
- extensively folded inner membrane into CRISTAE which act to increase surface area
62
Function of the mitochondria
power generators of the cell
-generate ATP via oxidative phosphorylation and the synthesis of certain lipids and proteins
63
Mitochondria contain their own DNA TRUE/FALSE
TRUE
64
what are intercellular junctions
specialised membrane structures which link cells together into a functional unit
65
where are intercellular junctions most prominent
epithelia
66
what are the 3 main types of intercellular junctions?
- Occluding junctions
- Anchoring junctions
- Communication Junctions
67
what is the other name of occluding junctions and why?
Zonula Occludens
Zonula: Bands
Occludens: Allows no movement off molecules
68
Role of occluding junctions
Prevents diffusion (does not allow movement of molecules)
69
How do occluding junctions appear?
bands tightly closing the cell membranes together
70
what do adherent junctions do?
link submembrane actin bundles of adjacent bundles
71
what is the other name for adherent junctions?
zonula adherens
72
how do adherent junctions work?
transmembrane CADHERIN molecules bind to each other in the extracellular space and through link molecules , to actin of the cytoskeleton.
73
what do desmosomes do?
link intermediate filaments of adjacent cells
74
what is the other name for desmosomes and why?
macula adherens or spot junctions
macula = spot
75
where are desmosomes most common?
the skin
76
What do communicating junctions do?
allow selective diffusion of molecules between adjacent cells
77
what are communicating junctions sometimes called and why?
gap junctions as they allow selective diffusion between cells
78
Communicating junctions allow he movement of all molecules between adjacent cells TRUE/FALSE?
FALSE
They are selective of the molecules allowed to pass through depending on size
79
how are communication junctions structured?
each junction is a circular patch studded with several hundred pores
80
what proteins produce the pores in communication junctions?
connexon proteins
81
where are communicating junctions most readily found?
epithelia, however are also present in some smooth muscle and in cardiac muscle
82
What is a junctional complex?
Close association of several types of junctions found in certain epithelial tissues
83
What are the 3 ways in which material can be transferred in and out of the cell?
- Diffusion
- Transport proteins
- Incorporation into vesicles (vesicular transport)
84
(BASIC) what is endocytosis?
The movement of material from the extracellular space into the cell
85
(BASIC) what is exocytosis?
the discharge of material from within the cell out into the extracellular space
86
How does endocytosis work?
-The cell membrane invaginates, fuses and the newly made endocytotic vesicle buds into the cell
87
what is the correct term for the endocytotic vesicle?
endosome
88
Endocytosis is receptor mediated TRUE/FALSE
TRUE
89
(BASIC) what is phagocytosis?
Bacteria or larger material can be incorporated into the cell from the extracellular space
90
what is the cell cycle?
the period of time between the birth of a cell and its own division to produce two daughter cells
91
what is the minimum period of time the cell cycle can last?
12 hours
92
what are cycling cells?
cells that continue to divide regularly in definite intervals
93
what the 2 main sections of the cell cycle?
mitosis and interphase
94
what are the stages of interphase?
G1 phase, S phase and G2 phase
95
what happens to the 2 identical daughter cells formed during mitosis?
they move into interphase
96
what is interphase?
the interval between the end of mitosis and the beginning of the next
97
Mitosis is the longest part of the cell cycle. TRUE/FALSE
FALSE
Interphase is the longest part of the cell cycle, cells spend 90-95% in this phase
98
What happens during the G1 stage of the cell cycle?
the cell responds to growth factors
99
when would the G0 phase occur?
between G1 and S
100
What happens to cells that cannot divide any further but can still proliferate by differentiation?
they enter the G0 phase
101
what is the G0 phase?
the state of cell cycle arrest/ a cellular state outwit the replicative cycle
Any DNA damage preventing division is repaired
102
when does the S phase of the cell cycle begin?
8hrs after mitosis
103
how long does the S phase of the cell cycle take to complete?
about 7-8hrs
104
what happens during the S Phase of the cell cycle?
new DNA is synthesised
105
what is the gap between the end of the S phase and the beginning of mitosis called?
G2 phase
106
how long roughly does the G2 phase take to happen?
2-4hrs
107
what happens during the G2 phase of the cell cycle?
the cell prepares for division;
-the nuclear membrane starts to disappear and chromosomes begin to condense
108
what type of cells does mitosis occur in most of?
somatic cells
109
what is the result of mitosis?
the distribution of the parent cell genome into 2 identical daughter cells
110
where are the paired centrioles located?
outside of the nuclear envelope in the cytoplasm
111
during interphase how are chromosomes seen?
inactive and uncoiled long threads
112
what are the 4 phases of mitosis?
prophase
metaphase
anaphase
telophase
113
what happens during prophase of mitosis?
- each chromosome splits into 2 chromatids except at the centromere
- centrioles separate by the elongation of the microtubules
- centrioles occupy the 2 opposite poles of the cell
114
what occurs between prophase and metaphase of mitosis?
PROMETAPHASE:
- nuclear membrane and nucleolus disappear
- chromosomes entangled in microtubule meshwork
115
what happens during metaphase of mitosis?
- centromeres present kinetochores
- chromosomal microtubules extend from centromeres to centrioles
- due to growth of chromosomal microtubules, chromosomes can now occupy equator
116
how long does metaphase of mitosis last?
20 mins
117
what are kinetochores?
bilateral discs coming from the centromeres of chromosomes during metaphase
118
what happens when colchicine is administered during metaphase?
arrest of cell division
119
how does colchicine arrest cell division in metaphase?
prevents the formation of spindle microtubules so chromosomes gather round the centrioles rather than along the cell equator
120
What happens during telophase of mitosis?
the daughter chromosomes are enveloped by a new nuclear membrane and the nucleolus reappears
the chromosomes uncoil and become thin threads again
the cytoplasm divides and two daughter cells are formed
121
what happens during cytokinesis?
the cytoplasm divides and two identical cells are formed
the cleavage furrow develops around the equator
the contraction of fibrillar component of cytoplasm help in hourglass constriction of cleavage.
122
what is non-disjunction?
due to abnormal function of spindle apparatus one or more chromosomes fail to migrate properly in ANAPHASE
one daughter cell receives extra chromosomes and one is deficient
123
what an isochromosome?
sometimes the centromere splits transversely rather than longitudinally resulting in two daughter chromosomes of unequal length
124
what are the levels of structural organisation?
-Cell
-tissue
-organ
-organ system
-organism
125
what are 3 histological techniques?
- Tissue Processing
- Embedding and Sectioning
- Staining
126
what does tissue processing do in histological testing?
preserves the tissue in its lifelike form and hardens it to be sliced
127
what does embedding and sectioning do in histological testing?
sections the tissue to ensure its thin enough for light to pass through
128
what does staining do in histological testing?
makes cells more visible under the microscope
129
what are the 4 steps involved in tissue processing?
fixation
dehydration
clearing
infiltration
130
what is the importance of fixation in tissue processing?
fixates the tissue with something like formalin
131
what is the importance of dehydration in tissue processing?
replaces H2O in tissue with alcohol (clearing agent cannot replace H2O)
132
what is the importance of clearing in tissue processing?
to replace all alcohol in the tissue with xylene
133
what is the importance of infiltration in tissue processing?
to replace xylene in the tissue with paraffin wax.
134
what temperature does the infiltration step of tissue processing occur at?
52-60 degrees Celsius
135
explain the steps of embedding and sectioning tissues
- take tissue out of cassette and place into a mould
- remove from mould when cooled
- Slice into extremely thin sections
136
what type of stain would be used on an acidophilic tissue, what colour would it be and what is a common stain used for this?
-An acidic stain
- Red or pink
- Eosin
137
what type of stain would be used on a basophilic tissue, what colour would it be and what is a common stain used for this?
- A basic stain
- Blue or purple
- Hematoxylin
138
what is the most common stain type used?
Hematoxylin and eosin (H&E)
139
what are the 4 basic tissue types?
Epithelium
Connective tissue
muscle tissue
nervous tissue
140
basic Role of epithelia
cover the surface of the body
lines hollow organs
forms glands
141
Basic role of connective tissue
forms the framework of the body
-Dynamic role in growth and homeostasis of tissues
142
basic role of muscle tissue
specialised to contract and generate force
143
three types of muscle tissue
cardiac
skeletal
smooth
144
basic role of nervous tissue
specialised to conduct impulses
145
what does nervous tissue consist of?
neurons and supporting cells
146
characteristics of epithelia
- Polarity (apical and basal end)
- Tightly adherent (cell junctions)
- Avascular (vessels beneath the epithelium)
147
what are the 2 main types of epithelium?
covering epithelium and glandular
148
what are the 3 types of covering epithelium and what is the difference between them all?
Simple
one single layer of cells
Stratified
2 or more layers of cells
Pseudo stratified
appears like more than one layer but only a single layer
149
what are the 3 categories of simple epithelia and what do the cells look like?
squamous (flat)
cuboidal (cube like)
columnar (column like)
150
what are the 4 different types of stratified epithelia?
squamous
cuboidal
columnar
transitional (top cell layer sometimes appears squamous and sometimes looks cuboidal)
151
what are microvilli?
minute fingerlike projections at the apical end of cells
increase the surface area of the cells to aid in absorption
152
what are goblet cells?
specialised cells that produce mucus
153
how are glands formed?
inward dipping of epithelium
154
what are the 2 types of glands formed by glandular epithelium?
exocrine glands and endocrine glands
155
how do endocrine glands secrete products?
directly onto a surface through a duct.
156
how do endocrine glands secrete products?
directly into the blood stream
157
What are the 2 (3) main types of connective tissue?
soft hard and special (blood/lymph)
158
soft connective tissue examples
tendons
ligaments
dermis of the skin etc...
159
hard connective tissue examples
cartilage and bone
160
what cells are found within connective tissue and what are they?
fibroblasts (produce and maintain the extracellular matrix)
adipocytes - fat cells
osteocytes - bone cells
chondrocytes - cartilage cells
161
what does the extracellular matrix consist of?
fibres
ground substance
tissue fluid
162
what does loose CT look like on imaging?
loosely packed fibres
thick collagen fibres
thin elastic fibres
lots if ground substance
163
what does adipose tissue look like on imaging?
little ECM
Little ground substance
cells filled with a fat droplet
nucleus appears small and pushed to the side
164
what does dense connective tissue look like on imaging?
dense packed fibres
regular dense CT if fibres are aligned (e.g. tendon)
irregular dense CT if fibres are in diff directions (e.g. skin dermis)
165
what is cartilage?
strong, flexible, compressible semi-rigid tissue
Avascular (receives nutrients through diffusion from adjacent tissues)
166
what are the 3 types of cartilage?
hyaline (ribs, joints, bronchioles, etc..)
fibrous (ext ear)
elastic (intervertebral discs/cushion)
167
hyaline cartilage
most common
collagen fibres
glossy appearance
clear matrix/ ground substance
GROUPS of chondrocytes in lacunae (holes/gaps)
168
Fibrocartilage
collagen fibres bundles in ECM
SINGLE chondrocytes in lacunae
169
Elastic Cartilage
Thin elastic fibres with ground substance in ECM
GROUPS of chondrocytes in lacunae
170
what are the 3 cell types in bone?
osteocytes
osteoclasts
osteoblasts
171
what does the ECM in bone consist of?
organic matrix (collagen, glycoproteins)
inorganic matrix ( calcium, phosphates and minerals)
172
what are the 2 types of bone and what do they look like?
compact bone - dense areas without cavities
spongy/cancellous/trabecular bone - fine meshwork
173
what are the contractile fibre cells in muscle tissue?
Actin (thinner)
myosin (thicker)
174
what are the 3 types of muscle tissue?
cardiac
skeletal
smooth
175
cardiac muscle features
short branching fibres
striated
single central nucleus
intercellular junction (intercalated discs)
gap junctions (to allow contraction)
involuntary
176
skeletal muscle features
prominent striations
long cylindrical fibres with no branches
multinucleated
peripheral nuclei
voluntary
177
smooth muscle features
involuntary
spindle shaped cells
central nucleus
178
what does nervous tissue consist of?
neurons and supporting cells with a connective tissue coat
179
what is the ratio of nerve cells to supporting cells
1:10
180
what is meant by multipolar neurones?
multiple dendrites one axon
181
what is meant by bipolar neurones?
one dendrite
one axon
both can branch afterwards
2 cytoplasmic processes
182
what is meant by pseudo-unipolar neurones?
one main cytoplasmic process
splits into a central process and a peripheral process
183
what cell type produces myelin in the CNS
oligodendrocytes
184
what cell type produces myelin in the PNS
Schwann cells
185
what do astrocytes do in the CNS?
support ion transport and form the blood brain barrier
186
what do microglia do in the CNS?
provide immune surveillance
187
what is the 4 layers of the GI tract?
- Mucosa (inner)
-Submucosa
- Muscularis
- Serosa/adventitia (outer)
188
what are the 3 layers of mucosa in the GI tract?
- Epithelium
- Lamina Propria (CT)
- Muscularis mucosa (muscular, divide mucosa and submucosa)
189
what are the 2 layers of the muscularis of the GI tract?
Muscularis interna
(nerve plexus)
Muscularis externa
190
what are the variations in mucosa in the GI tract
protective (oral cavity, pharynx, oesophagus, anal)
-Non-keratinized stratified, squamous, epithelium
Absorptive (small intestine)
-simple columnar epithelium with VILLI, and tubular glands.
secretory (stomach)
- simple columnar epithelium with extensive tubular glands
protective and absorptive (large intestine)
- simple columnar epithelium with tubular Glands
191
what are the associated organs of the GI system?
-Salivary glands
- Liver
- Gall bladder
- Pancreas
192
what are the 3 salivary glands?
parotid
submandibular
sublingual
193
what do the striated ducts in the salivary glands do?
modify the saliva
194
Organization of the Liver
Contains hepatocytes
Contains hepatic lobules
195
what are hepatic lobules?
hexagonal arrangements
central vein running through the centre
at each corner (bile duct, portal vein and hepatic artery)
blood flows from portal and hepatic artery towards central vein through SINUSOIDS
196
Is the pancreas an exocrine or endocrine gland?
Both
the pancreas has an exocrine portion and an endocrine gland so is a MIXED GLAND
197
What is the exocrine portion of the pancreas and its function?
serous acini and produced digestive juices, proteases and lipases
198
what is the endocrine portion of the pancreas and what is its function?
islets of langerhans
specialised to produce insulin and glucagon
199
what do A cells in Islets of langerhans do in the pancreas?
produce glucagon
200
what do B cells in Islets of Langerhans do in the pancreas?
produce insulin
201
what does the respiratory system consist of?
upper resp tract
trachea
bronchial tree
lungs
202
what are the 3 layers of the trachea?
respiratory epithelium
lamina propria
hyaline cartilage of tracheal ring
203
what type of epithelium is present in the trachea?
pseudo-stratified, ciliated columnar epithelium with goblet cells
204
bronchi structure
large diameter
204
bronchi structure
large diameter
205
bronchi structure
large diameter
have hyaline cartilage in their walls
206
bronchioles structure
small airways
no cartilage in wall
predominantly smooth muscle in their wall
207
what type of epithelium line alveoli?
simple squamous for gas exchange
208
structure of kidney
cortex
medulla
nephrons
209
what is the medulla of the kidney consisted of?
the loop of henle
thick and thin segments
collecting duct
210
what is the cortex of the kidney consisted of?
renal corpuscle
proximal convoluted tubule
distal convoluted tubule
