Histology Flashcards
1
Q
Describe the structure of an artery
A
Blood flows through lumen which is bound by a basement membrane on which there is endothelium (Simple squamous)
This is surrounded by connective tissue INTIMA
This is surrounded by internal elastic lamina (Elastic tissue =)
Around this is the MEDIA which contains some smooth muscle then there Is the external lamina and the adventitia on the outside
2
Q
The closer an artery is to the heart, the greater the amounts of what found in its wall?
A
Elastic tissue
3
Q
How is the tendency of the aorta to over distend during systole overcome by its structure?
A
Media contains abundant concentric sheets of elastin arranged in circumferential sheets between layers of smooth muscle
4
Q
Which blood vessels are the resistance arterioles of the circulatory system?
A
Arterioles
5
Q
Define an arteriole
A
Defined as having 3 or fewer muscle layers in their media or are up to or less than 100um in diameter
Lack an external elastic lamina and the internal elastic lamina is poorly defined
6
Q
Describe the structure of capillaries
A
Hace endothelial cells on a basement membrane and are line by pericytes forming discontinuous layer which becomes continuous as capillaries get larger
Where the vascular endothelium is incomplete there are gaps called fenestrations
7
Q
What is the main structural differences between arterioles/arteries and veins
A
Arteries and arterioles have thicker muscular walls and a thinner lumen than veins
8
Q
Describe the structure of veins
A
Have a wide lumen surrounded by a basement membrane upon which is a layer of endothelium. There is then a thin layer of intima, and internal elastic lamina then media and adventitia
9
Q
What is the main structural difference in the walls of arteries and veins
A
Veins don’t have an external elastic lamina
10
Q
Describe the structure of venues
A
Wall consists of endothelium reinforced by connective tissues with contractile pericytes around the outside. These pericytes are replaced by smooth muscles as the venues become veins
11
Q
Describe the structure of lymphatics
A
Thin walled with valves. Walls contain mixture of collagen and elastin with little smooth muscle and are typically filled with an amorphous colloid plasma that stains pink with H and E
12
Q
What are the two parts of the nervous system
A
CNS - brain and spinal cord
PNS - axon processes to target organs an tissues
13
Q
Myelin is produced by what cell in the peripheral nerves
A
Schwann cells
14
Q
Do axons stain with H and E
A
No
15
Q
Define endoneurium
A
Between individual axons
16
Q
Define perineurium
A
Surrounds groups of axons to form fascicles
17
Q
Define epineurium
A
Binds fascicles together to form nerve fibres
18
Q
What is found in a neuromuscular bundle?
A
Nerve, arteriole and venule
19
Q
What stain is used to identify myelin?
A
Silver stain
20
Q
What are the main components of connective tissue
A
Elastin, collagen, amorphous material which has a high molecular weight, strongly hydrophilic and negatively charged to retain water
21
Q
GAG’s are synthesised by what cell types?
A
Epithelial, muscle, cartilage and bone but mostly by fibroblasts
22
Q
Define soft connective tissue
A
Flexible and gel like - divisible into fibrous or fatty connective
23
Q
Define hard connetive tissue
A
Forms of bone
24
Q
Define fibrous connective tissue
A
Contains large numbers of collagen, elastin and reticulin fibres
25
Define loose irregular fibrous connective tissue
Contains few randomly orientated fibres
26
Define dense irregular fibrous connective tissue
Contains large number of fibres with little amorphous material
27
Define regular dense fibrous connective tissue
Fibres arranged in parallel bundles
28
Define fatty connective tissue
Contains mainly fat cells with intervening blood vessels, particularly capillaries
29
Where are connective tissue cells mainly derived from?
Mesenchymal cells
30
What are the main cell types found in connective tissue?
Adipose
| Fibroblasts/Fibrocytes
31
What are the main visible fibres found in connective tissue?
Collagen
Elastin
Reticulin
32
What are the main components of ground substance
Proteoglycans
Glycosaminoglycans
Laminin/Fibronectin (Invisible fibres)
33
Does ground substance stain with H and E?
No, appears as white space
34
What cell type secretes collagen
Fibroblasts
35
What are the type 1 collagens
Skin, bone, teeth and organ capsules
36
What are the type 2 collagens
Cartilage
37
What are the type 3 collagens
Liver, bone marrow and spleen
38
What are the type 4 collagens
Basement
39
What are the type 5 collagens
Placenta
40
Describe the structure of a tropocollagen subunit
Three linear polypeptide chains wound together in an alpha helix
41
Give an example of regular dense connective tissue
Tendon
42
Give an example of irregular dense connective tissue
Penile fascia
43
Describe reticulin
type 3 collagen forms supporting scaffold for liver, bone marrow, kidney, spleen and lymph nodes
44
Is reticulin visible on H and E
No, needs a silver stain that makes the collagen appear as black lines
45
Van Geisons stain will stain elastic fibres and sheets what colour?
Dark brown
46
Describe white adipose
Large cells with a single fat globule in each cell and appear as an empty white space
47
What is the function of white adipose?
Protects the vital organs and serves as an energy store
48
Describe brown adipose tissue
found across the shoulders and backs of newborns
| Pink foamy appearance
49
What is the function of brown adipose
Thermal regulation - generates heat upon breakdown
50
Where is cartilage derived from
Undifferentiated mesenchymal cells
51
Describe the structure of cartilage
Chondroblasts become embedded within a dense GAG matrix containing variable amounts of collagen and elastic tissue - the chrondroblasts mature into chondrocytes which are unable to migrate through the matrix
52
What is the fibrous capsule surrounding cartilage called?
Perichondrium which contains undifferentiated progenitor cells that can differentiate into chondroblasts
53
Give an example of a glycosaminoglycans
Hyaluronic acid
54
Give two examples of proteoglycans
Chondroitan sulphate
| Keratan glycan
55
Give three types of cartilage
Hyaline
Elastic
Fibro
56
Where is hyaline cartilage found
In synovial joints
| Rings of the trachea and the cartilage of the larynx
57
Where is elastic cartilage found?
Pinna of the ear
| Epiglottis
58
Where is fibrocartilage found
In the annulus fibrosis in the intervertebral discs and in the pubic symphysis
59
Give three locations of visceral smooth muscle
Wall of the intestine
Arterial wall
Bronchioles of the lung
60
Give three locations of voluntary skeletal muscle
Skeletal muscles
Larynx
Diaphragm
61
Other than muscle name three other contractile cell types
Pericytes
Myo-Fibroblasts (Scar formation)
Myo-epithelial cells (Expression of milk during lactation)
62
Describe the structure of a gap junction
Consists of 6 connexion proteins that link the interior of adjacent smooth muscle cells with a guarded central pore that permits the passage of small molecular weight molecule, electrically coupling them
63
What are the functions of epithelial cells
Protection - skin
Absorption - gut
Secretion - pancreas, liver and GIT
64
Describe the structure of a simple epithelia
Single layer of cells on a basement membrane
65
What function are simple epithelia associated with?
Absorption and secretion
66
Describe the structure of stratified (Compound) epithelia
Two or more layers of cells on a basement membrane
67
What function is associated with stratified epithelium
Protection - found in areas of the body that experience frictional and abrasive forces such as the skin, mouth, throat, oesophagus and vagina
68
What is the simple squamouss epithelium that lines the blood vessels called?
Endothelium
69
What is the simple squamous epithelium that lines outside the lungs called
Mesothelium
70
What is the simple squamous epithelium that lines abdominal organs called
Peritoneum
71
Describe the structure of simple cuboidal epithelium
Single layer of cells with similar height and width on a basement membrane with a central spherical nuclei
72
Where are simple cuboidal epithelium found?
Occur in the ducts of glands such as sweat, salivary and pancreatic (Exocrine glands)
73
Describe the structure of simple columnar epithelium
Single layer of cells that are taller than they are wide sat on a basement membrane with an spheroidal nucleus that's nucleus is perpendicular to the base of the cell - may or may not have microvilli or villi to increase surface area
74
Where are simple columnar epithelium found?
Lining the stomach, intestines and uterus
75
Where are microvilli found?
Gut enterocytes
76
Where are villi found?
Respiratory tract
77
Describe the structure of microvilli
Projections on the luminal surfaces of absorptive cells such as columnar epithelium that increase SA and are maintained by a core of actin filaments. covered in a rich glycoalyx and goblet cells
78
What stain is used to stain columnar epithelial cells a dark magenta
PAS
79
Describe the structure of cilia
0.2um motile projections on luminal surfaces of cells that contain contractile proteins that enable the wafting of mucus
80
Where are cilia most commonly found?
Airways of the nose, larynx, bronchial tree and Fallopian tubes
81
What is the purpose of keratin?
Waterproofs cells
82
Where is stratified squamous non-keratinising epithelium commonly found?
Mouth, oropharynx, oesophagus and vagina (Wet areas)
83
Where are keratohyaline granules found?
At the boundary between living epithelial cells and dead pink keratinising layers
84
Describe the structure of pseudo stratified epithelium
Single layer of cells of variable height mimicking multiple layers but all the cells are in contact with the basement membrane
85
Where is pseudo stratified epithelium most commonly found?
Trachea and the bronchi
86
How are cells replaced in stratified epithelium
Vertical migration
87
How are cells replaced in pseudo stratified epithelium
Lateral migration
88
Describe the structure of urothelium
Looks stratified but there is a surface layer of umbrella cells (3-7layers thick) that is not in contact with the basement membrane
89
Name two proteins found in the basement membrane?
collagen IV
| Fibronectin
90
What are the two types of epithelial junction
Occluding (tight) junctions
| Desmosomes (Anchoring junctions)
91
Describe the structure of occluding junctions
Band like fusions between cells that are impervious to molecules
92
Describe the structure of desmosomes
Plaques that form physical joins between cells and connect the cytoskeletons of adjacent cells
93
What is the function of desmosomes
To spread mechanical forces across several cells
94
What do adherent junctions connect
Link actin filament network between adjacent cells to the extracellular matrix
95
What do desmosomes connect
Intermediate filament networks of adjacent cells
96
What do hemidesmosomes connect
Intermediate filament network of cells to the extracellular matrix (Basement membrane)
97
Epithelial cells that secrete protein have what characteristic intrinsic organelles
Large nuclei and abundant endoplasmic reticulum
98
Mucin secreting epithelial cells have what characteristic intrinsic organelles
Expanded Golgi system
99
Steroid secreting epithelial cells have what characteristic intrinsic organelles
Smooth endoplasmic reticulum
100
Define apocrine
Secrete by budding
101
Define endocrine
Secrete directly into the blood
102
Define holocrine
releasing a secretion that is the product of the degradation of cell
103
Define exocrine
Secrete by passage of liquid across membranes
104
What percentage of blood is cellular
44%
105
What percentage of blood is plasma
56%
106
What are the components of plasma
```
Water
Salt and minerals
plasma Proteins (Albumin, globulins and fibrinogen)
Hormones and signalling molecules
Clotting factors
```
107
Define blood serum
Plasma minus the clotting factors
108
What stain is used to examine the composition of blood
Romanowsky stain
109
What is the lifespan of a red blood cell
120 days
110
Where are RBC produced
Liver (Foetus) and bone haematopoeitic marrow
111
What is a reticulocyte
An immature RBC that still has some ribosome remnants
112
Describe the structure of RBC
```
Enucleate
Biconcave
6.5-8.6um in diameter
Major protein is haemoglobin
Major protein of endoskeleton is spectrin
```
113
Where are RBC normally destroyed
Liver and spleen
114
Define a granulocyte
Contains visible granules in cytoplasm
115
Which leucocytes are granulocytes
Neutrophils
Eosinophils
Basophils
116
Define granulocyte
No visible granules in the cytoplasm
117
Which leucocytes are agranulocytes
Lymphocytes and monocytes
118
Which leucocyte has a multi-lobed nucleus
Neutrophils
119
Which leucocyte has a nucleus and prominent dark blue granules
Basophils
120
Which leucocyte has a nucleus and bright pink granules
eosinophils
121
Which leucocyte are small cells with dark stained nucleus and little cytoplasm
Lymphocyte
122
Which leucocyte has a kidney shaped nucleus
Monocyte
123
Describe the properties of neutrophils
Most common
Multi lobed nucleus
Granular cytoplasm
12-14um in diameter
124
What is the function of neutrophils
Phagocytic (Primary phagocytes)
Engulf and destroy bacteria and foreign macromolecules
Operate in hostile environments (Ie low oxygen tension)
125
What are the three types of cytoplasmic granule found in neutrophils
Primary granule
Secondary granule
Tertiary granule
126
Describe primary granules
Lysosomes such as myeloperoxidase and acid hydrolase
127
Describe secondary granules
Specific granules that secrete substances that mobilise inflammatory mediators
128
Describe tertiary granules
Gelatinases that break down proteins and adhesion molecules and help the neutrophil move out the blood vessel and into the tissue
129
Describe the properties of eosinophils
1% of WBC
Increase in number in response to allergic reaction and parasite infections
Bi/multi-lobed nucleus
Bright pink lozenges cytoplasmic granules with crystalline inclusions (Charcot laymen crystals)
130
What is the function of eosinophils
Phagocytic with particular affinity for antige/antibody complexes
Receptors for IgE on surface
Inhibit mast cell secretion and neutralise histamine secretion thereby restricting the inflammatory response
131
Describe the properties of basophils
0.5% of WBC
14-16um
Dark blue stained cytoplasmic granules that contain histamine
132
What is the function of basophils
involved in the inflammatory reactions and act to prevent coagulation and agglutination
Release histamine and other vast-active gents in reponse to allergens to increase blood flow to an area
results in immediate hypersensitivity reactions - anaphylaxis
133
What are the two divisions of lymphocytes
B cells
| T cells
134
What are B cells
Become plasma cells and secrete antibodies
135
Where are B cells formed
In the bone marrow
136
What are T cells
Involved in cell mediated immunity
137
Where are T cells formed?
In the thymus
138
What is the function of T helper cells
Help B cells and activate macrophages
139
What is the function of T cytotoxic cells
Kill previously marked target cells
140
What is the function of T suppressor cells
Suppress the T helper cells and hence suppress the immune response
141
What is the function of natural killer cells
Mainly kill virus infected cells
142
Describe the properties of monocytes
Kidney shaped nucleus
15-20um diameter
differentiate into one of several cell types
143
What are the 5 types of cell that monocytes differentiate into
```
Tissue macrophage
Kupffer cells
Osteoclasts
Antigen presenting cell
Alveolar macrophages
```
144
Describe the properties of platelets
Fragments of cells derived from large multinucleate megakaryocytes in bone marrow
1-3um in diameter
Responsible for clotting of blood
145
Define haematopoiesis
Formation of blood cells
146
All blood cells are derived from what multipotent haemopoietic stem cell
Haemocytoblast
147
What two cells does the haemocytoblast form
Common myeloid progenitor
| Common lymphoid progenitor
148
What is the precursor cell to leucocytes
Myeloblast
149
Define histology
Study of microscopic structure of biological material and the ways the components are structurally and functionally related
150
Define cytology
Analysis of fine structure of cells by light microscopy
151
Describe how histological slices are produced
Tissue preserved in formalin then embedded in paraffin which requires removal of water then 4 micron slices are taken, mounted and stained
152
H and E stains nuclei and cytoplasm what colours
Nuclei = blue
Cytoplasm = pink
Extracellular fibres also stain pink
GAG's appear as white
153
What PAS stain and what colour
Sugars - goblet cell in small intestine and GAG's in intestinal border
stains magenta
154
What does Van Giesons stain and what colour
Elastic fibres = brown
Collagen = pinkish-red
Muscle = yellow
155
What does alcian blue stain
Mucins secreted by epithelial cells
156
What are the 6 types of cell shape
```
Rounded
Polygonal
Fusiform
Squamous
cuboidal
columnar
```
157
Why are some cells smaller with less cytoplasm and smaller nuclei?
Because the are metabolically inactive or dormant
158
Which cells tend to have elaborate cell machinery and nucleoli specialised for DNA transcription?
Metabolically active cells
159
Which cell types have a lifespan of days
Cells lining the gut
160
Which cells have a lifespan of months
Blood (120days)
Skin
Connective tissue
161
Which cells have a lifespan of years
Bone and tendon
162
Which cells have a lifespan of nearly a whole life
Skeletal muscle
163
Which cells last your whole life
Nerve and brain
Cardiac
Germ cells
164
Name the 6 membranous organelles
```
Nucleus
Lysosome
Mitochondria
Peroxisome
Golgi
Endoplasmic reticulum
```
165
Name the 4 non-membranous organelles
Ribosomes
Centrosomes
Centrioles
Basal bodies
166
What is the nuclear lamina
Network of protein filaments (20nm thick) composed of three proteins, Lamins A, B and C, which interact with the nuclear membrane proteins and act as a nuclear cytoskeleton
167
Darker areas of the nucleolus consist of what sort chromatin
Heterochromatin
168
Lighter areas of the nucleolus consist of what sort of chromatin
Euchromatin
169
What is the size and function of the nucleolus
1-3 microns in diameter and acts as the site of ribosomal RNA formation
170
What are the three different regions of the nucleolus
```
Pars Amorpha (Pale areas)
Pars Fibrosa (Dense stain regions)
Pars Granuloase (Granular regions)
```
171
What is the function of the pars amorpha
Contain specific RNA binding proteins and correspond to large loops of transcribing DNA containing ribosomal RNA genes
172
What is the function of the pars fibrosa
Correspond to the transcripts of ribosomal RNA genes beginning to form ribosomes
173
What is the function of the pars granulosa
Correponds to RNA containing maturing ribosomal particles
174
What is the function of the pars granulosa
Correponds to RNA containing maturing ribosomal particles
175
Describe the structure of chromatin
DNA organised around histones into Nuclesomes which are wound into helix filaments 30nm in diameter to form chromatin which is then wound again into supercoiled structure
176
What does euchromatin represent
Light stained areas with unwound chromatin that is actively transcribed into cellular DNA
177
What does heterochromatin represent
Dense stained areas that are highly condensed and transcriptionally inactive
178
What is the outer membrane of mitochondria associated with
Lipid synthesis
| Fatty acid metabolism
179
What is the inner membrane of mitochondria associated with
Respiratory chain (ATP production)
180
What is the matrix of mitochondria associated with
TCA cycle
181
What is the inter membranous space of the mitochondria associated with
Nucleotide phosphorylation
182
Function of RER
Protein synthesis
183
Function of SER
Lipid synthesis
184
Function of golgi
Synthesises steroids and other lipids
| Detoxifies alcohol and drugs
185
Describe the cis face of the Golgi apparatus
Nuclear facing
| Receives transport vesicles from the SER and phosphorylates some proteins
186
Describe the medial face of the Golgi apparatus
Central part that forms oligosaccharides by adding sugars to lipids and peptides
187
Describe the trans golgi network
Outer face that sorts macromolecules into vesicles which bud from the surface become lysosomes, migrate to the plasma men and fuse or become secretory vesicles that store protein for later release
188
Describe the structure of lysosomes
Intracellular digestion system
| H+-ATPase on membrane creates low internal pH and also contains acid hydrolyases which degrade proteins
189
Describe the structure and function of peroxisomes
Membrane bound organelles which oxidise long chain fatty acids by producing H2O2 - neutralise free radicals, detoxify alcohols and other drugs
190
What is the function of cytoskeleton
Determines cell shape, structure, organises cell contents and directs the movement of materials in the cell
191
What are the three main protein filaments found in the cytoskeleton
Microfilaments
Microtubules
Intermediate fibres
192
Describe the properties of microfilaments
```
smallest fibre (5nm)
Made of actin which forms a bracing mesh on the inner surface of cell membrane to maintain cell shape
```
193
Describe the properties of microtubules
25mm diameter
When cells divide a network of microtubules from tubulin protein acts as a scaffold - made of alpha and Beta tubulin which arranged into groups of 13 to form hollow tubes
194
Describe the properties of intermediate filaments
10nm in diameter
6 different types
Anchored to the transmembrane proteins and spread tensile forces throughout the tissues
195
What are the 6 types of intermediate filament
Cytokeratins - epithelial cells
Desmin - Myocytes
Glial fibrillary acidic protein - astrocytic glial cells
Neurofilament protein - neurons
Nuclear laminin - nuclei of all glial cells
Vimentin - mesodermal cells
196
What is lipofuscin
Membrane bound orange brown pigment
197
Define transmission electron microscope
Resolution of sub cellular structures in thin tissue sections
198
Define scanning electron microscope
Resolution of three dimensional sub cellular structures
199
What are the three layers of the cardiac muscle
Myocardium
Epicardium
Pericardium (Outermost)
200
Describe the structure of cardiac muscle
Striated with myofibrils in register
Myofibrils have repeat sarcomeres that given central striations but do not form a syncinctium
Central nuclei for each cardiac muscle cell
Intercalated discs which connect actin filaments of adjacent myocytes
201
Where are the largest myocytes found
Wall of the left ventricle
202
Describe the structure of cardiac valves
Covered by endothelium and consist of thick collagen fibres with some elastic tissue
Free margins are connected to papillary muscles by chord tendinae
203
What are the three layers found in cardiac valves
Fibrosa (Dense fibrous CT)
Spongiosa (Loose fibrous CT)
Ventricular (Collagen and elastin)
204
Where are the nodules of arantius found
In aortic valve cusps
205
Describe skeletal muscle
Striated
Nucleus at edge
No branching
206
describe cardiac muscle
Striated
Central nucleus
Branching
207
Describe smooth muscle
Not striated
Central nuclei
No branching
208
What are the 8 functions of the respiratory tract
```
Air filtration
Humidification
Warming inspired air
Olfaction
Protection from infection
Speech
Gas transport
Gas exchange
```
209
What epithelium lines the conducting airways
Simple or pseudo stratified columnar ciliated epithelium punctuated with mucus secreting goblet cells
210
What are the functions of the nose
Warming
Filtration
Humidification
Olfaction
211
What epithelium lines the root of the nasal cavity (Cribriform plate)
Pseudostratified columnar epithelium of olfactory receptor cells with supporting sustentacular cells and basal cells
212
What are the functions of the nasopharynx
Gas transport
Humdification
warming o
olfaction
213
What epithelium lines the nasopharynx
Respiratory epithelium
214
What are the function of the nasal sinuses
Lower weight of the skull
Add resonance to the skull
Humidify and warm inspired air
215
What epithelium lines the nasal sinuses
Respiratory epithelium
216
What epithelium lines the larynx
Respiratory epithelium except the vocal chords which are lined by a stratified squamous
217
What epithelium covers the vocal chords
Stratified squamous overlying a loose irregular fibrous tissue (Reinke's Space)
218
Which epithelium covers the trachea
Respiratory epithelium
219
Describe the histology of the main, lobar and segmental bronchi
```
Smooth muscle
Partial cartilaginous rings
Respiratory epithelium
Some basal neuroendocrine cells
Seromucinous glands and goblet cells
```
220
Describe the histology of the bronchioles
```
Smooth muscle
Ciliated columnar epithelium
Some basal neuroendocrine cells
Few goblet cells
Clara cells
```
221
Where are Clara cells most numerous
Terminal bronchioles
222
What are the functions of Clara cells
Oxidise inhaled toxins
Antiprotease function
Surfactant production/Elimination
Stem cell function
223
Describe the structure and properties of type I pneumocytes
Squamous epithelial cells
Contain few organelles to be as thin as possible - flat nucleus
40% of cell population but 90% of SA
Embedded within are fibroblasts that produce reticulin and elastic tissue important for the recoil of lungs during exhalation
224
Describe the structure and properties of type II pneumocystes
60% of cell pop but cover 5-10% of SA
Rounded, columnar with round nucleus
Rich in mitochondria
Produce surfactant from around 28th week of intra-uterine life
225
Describe the structure and function of alveolar macrophages
Phagocytic cells derived from blood monocytes found in the interstitial connective tissue of alveolar walls
Phagocytose particulates including ducts and bacteria
226
What is the purpose of pores Kohn and why are they potentially problematic
Help to equalise the pressure between adjacent alveoli and help the lungs to inflate easily but should infection reach the lungs it will help it to spread
227
What epithelium lines the oral cavity
Non keratinised stratified squamous epithelium
228
What epithelium lines the oesophagus
Stratified squamous with submucosal glands which secrete mucus onto surface to help lubricate food
229
What are the 4 layers of the gut wall from innermost to outermost
Mucosa
Submucosa
Muscularis propria
Serosa
230
Which cells are responsible for the nervous control of the smooth muscle of the gut and where are they found
Ganglion cells
| Found in the muscularis propria between the longitudinal and circular muscle layers
231
What is the function of the interstitial cells of Cajal
Pacemakers of contraction in the GIT
232
Describe the layers of the gut wall
```
Epithelium
Basement membrane
Lamina propria
Muscularis mucosae
Submucosa
Inner circular layer (Muscularis propria)
Outer longitudinal layer (Muscularis Propria)
Adventitia (Serosa)
```
233
Describe the layers of the stomach wall
```
Epithelium
Basement membrane
Lamina propria
Muscularis mucosae
Submucosa
Inner oblique, middle circular and outer longitudinal layers of the muscularis propria
```
234
What is the epithelium lining the lips
Non keratinised stratified squamous epithelium
235
What is the epithelium of the skin around the lips
Keratinised stratified squamous epithelium
236
What is the epithelial covering of the tongue
Converted by non-keratinised stratified squamous epithelium on ventral surface and keratinised on its dorsal surface
237
What is the name of the V-Shpaed row of papillae that separate the anterior 2/3 and posterior 1/3 of the tongue
Circumvallate papillae
238
Where are fungiform papillae found
Tip and sides of the tongue
239
Where are filiform papillae found
Cover whole anterior 2/3 of tongue
240
What epithelium lines ducts of the parotid acini
Simple cuboidal epithelium
241
What epithelium lines the epiglottis
Stratified squamous epithelial that becomes respiratory epithelium at the beginning of the respiratory tract
242
Describe the muscle types found in the oesophagus
Skeletal muscle at the proximal end but smooth muscle at the distal end
243
What is the epithelial lining of the stomach
Simple columnar epithelium punctuated by gastric pits
244
How does the muscular propria layer differ in the gut tube and stomach
Stomach has three layers compared to the guts two in order to help churn food
245
Where in the stomach are full gastric glands found
Body and fundus
246
How do glands found in the pylorus and cardia of the stomach differ from the full gastric glands
devoid of parietal and chief cells
247
Describe the structure of parietal cells
Found in gastric glands of body and fundus and occupy upper parts of these glands - are globular in shape and stain bright pink
248
Describe the structure of chief cells
Pyramidal in shape and occupy deeper parts of the gland
| Cytoplasm stains blue with H and E
249
How do gastric glands in the cardiac and pylorus regions of the stomach differ from those in the fundus and body of the stomach
Ones in the cardia and pylorus are shorter and coiled whereas those in the fundus are longer and straight
Those in the cardia mainly consist of mucous neck cells
250
What are the lymphatics in villi called
Lacteals
251
What type of epithelia covers the villi and what are the main two cell types interspersed in the epithelia?
Simple columnar epithelia
Enterocytes (Absorptive cells)
Goblet cells (Mucus secreting)
252
What lies between the villi?
Straight tubular glands called crypts of Liberkuhn that contain a stem cell population to replace villi cells
253
What is the functional importance of the glycocalyx found at the brush border of enterocytes
Acts as a filter and as an anchorage for exo-enzymes
254
What glands lie in the submucosa of the duodenum and what are their functions
Brunner's Gland which secretes alkaline substance that helps to neutralise chyme entering the stomach
255
Where do newly formed enterocytes from crypts go in the small intestine
Migrate onto the villi
256
Where do newly formed enterocytes from crypts go in the large intestine?
Spread out on to the flattened surface of the gut
257
What are Paneth cells? where do they lie and what is their function? How can they be identified
Lie at the bottom of crypts
Secrete lysozyme which is important for bacterial cell wall breakdown and regulation of bacteria flora
Cells can be recognised by their pink staining cytoplasm
258
Describe the histology of the vermiform appendix
Arises from the caecum and is lined by simple columnar epithelium with goblet cells but no villi
Lamina propria and submucosa are filled with lymphoid
No muscularis mucosa but muscularis External show two layers of smooth muscle
Taenia coli originate at base of appendix
259
What epithelium lines the colon and the rectum
Simple columnar epithelium
260
What epithelium lines the anal Canal
Stratified squamous that becomes keratinised at the distal end
261
What are the 5 main functions of the liver
Creation and storage of energy in the forms of fat and glycogen
Synthesis and secretion of plasma proteins
Deamination of amino acids and production of urea
Uptake, synthesis and excretion of bilirubin and bile acids
Detoxification and inactivation of drugs toxins by oxidation, methylation and conjugation
262
Describe the structure of a liver lobule
Lobule is polygonal in shape and consists of chords of hepatocytes which radiate from a central vein and between which are sinusoids that bathe hepatocytes in a mixture of arterial (30%) and venous (70%) blood
263
Is the oxygenation of hepatocytes equal
No, hepatocytes closest to the edge of the lobule, near the hepatic veins and arteries will receive more O2 and glucose compared to those in the centre because blood flows from the portal tract through the sinusoids and drains into the central vein so those near the edge extract glucose and oxygen first
264
What are the three surfaces of an individual hepatocyte
Sinusoidal (70%) - Exchange of material with blood (Space of Disse)
Canalicullar (15%) - Excretion of bile
Intracellular (15%) - Hepatocyte to hepatocyte
265
Where are hepatic stellate cells found
Space of disse
266
What is the name of macrophages in the lining of the sinusoid epithelium and what is their function
Kupffer cells - phagocytose and destroy blood borne pathogens, produce bilirubin
267
What stain is used to show Kupffer cells
Perl's Stain
268
What epithelium lines the billiary tree
Cuboidal epithelium which in smaller vessels is single layered but towards the distal end it becomes stratified
269
What epithelium lines the gall bladder
Simple columnar epithelium thrown into folds with microvilli on luminal surface to enable water and salt absorption
270
Exocrine parts of the pancreas account for what percentage of the total gland
90%
271
List the duct system that secretions of the acing pancreatic cells drain into from first to last
Centroacinar duct
Intercalated duct
Interlobular duct
Main pancreatic duct
272
define endocrine gland
Secretes hormones into the bloodstream for circulation around the body
273
What are the 4 types of hormone
1. Derived from AA (Adrenaline)
2. Small peptides (Vasopressin)
3. Proteins (Insulin)
4. (Testosterone)
274
What is the origin of the posterior pituitary
Neuronal origin - down growth of the brain that is joined by the pituitary stalk to the median eminence of the midbrain
275
What nuclei are found in the posterior pituitary
Supraoptic
| Paraventricular
276
What is the origin of the anterior pituitary
Epithelial origin derived from the roof of the primitive gut tube - adheres the to the anterior border of the posterior pituitary and surrounded the pars tuberalis
277
Define portal system
One that starts and ends with capillaries
278
Describe how the pituitary portal system works
Trophic hormones produced by the anterior pit regulated by releasing or inhibiting factors produced by the hypothalamus. Neurones project as far as the median eminence where they release their secretion which are taken up into the capillaries of the pituitary portal system and carried to the anterior love where they are discharged and act upon the hormone secreting cells
279
What are the 5 main classes of anterior pituitary hormone?
```
Somatotrophs (GH)
Lactotrophs (PRL)
Corticotrophs (ACTH)
Thyrotrophs (TSH)
Gonadotrophs (FSH and LH)
```
280
What is the name given to cells that secrete growth hormone and prolactin
Sommatomammotrophs
281
What are the three groups that anterior pituitary cells were previously classified into
Stain heavy with acid (Alpha cells/Acidophils)
Stain heavy with basic dyes (Beta cells/basophils)
Stain weakly with either dye (Chromophobes)
282
What do herring bodies in the posterior pituitary contain
Dark stained neurosecretory granules (Oxytocin or vasopressin) bound to a carrier protein (Neurophysin)
283
What is the pars tuberalis
Upward extension of the anterior pituitary lobe that surrounds the pituitary stalk to form the puberal lobe which contains mostly gonadotrophin cells
284
What is the function of the pineal gland
Consists of clumps of pinealocytes linked by glial cells which received their innovation from autonomic nervous system and secrete melatonin which is important in regulating dinural rhythms
285
What two hormones does the thyroid gland secrete
Thyroxine and calcitonin
286
Describe the structure of thyroid follicles, what do they secrete?
cuboidal epithelial cells arranged in hollow spheres form the follicle with the centre of each follicle filled with an amorphous eosinophilic material called colloid which is rich in thyroglobuli - produces thyroxine
287
Describe the process of follicular phases
Thyroid follicle undergoes cycle of activity by first synthesising thyroglobulin which they store in the follicle. After a dormant period, the cell reabsorbs and breakdowns the colloid releasing metre-iodothryonine (T4) into the blood
288
What happens the cuboidal epithelium during the active follicular phases of the thyroid
Cells enlarge and appear high cuboidal in shape whereas during the dormant period the cells lose some organelles and present a low cuboidal profile
289
Where are C cells of the thyroid found and what do they produce
Found in clumps between follicles (Parafollicular) and produce calcitonin
290
What are the cells of the parathyroid gland
Main cell type is chief cells which are small, pale stained cytoplasm with large numbers of small granules
also have larger pink stained oxyphil cells
