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

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2
Q

The closer an artery is to the heart, the greater the amounts of what found in its wall?

A

Elastic tissue

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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

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4
Q

Which blood vessels are the resistance arterioles of the circulatory system?

A

Arterioles

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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

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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

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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

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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

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9
Q

What is the main structural difference in the walls of arteries and veins

A

Veins don’t have an external elastic lamina

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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

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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

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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

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13
Q

Myelin is produced by what cell in the peripheral nerves

A

Schwann cells

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14
Q

Do axons stain with H and E

A

No

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15
Q

Define endoneurium

A

Between individual axons

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16
Q

Define perineurium

A

Surrounds groups of axons to form fascicles

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17
Q

Define epineurium

A

Binds fascicles together to form nerve fibres

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18
Q

What is found in a neuromuscular bundle?

A

Nerve, arteriole and venule

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19
Q

What stain is used to identify myelin?

A

Silver stain

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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

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21
Q

GAG’s are synthesised by what cell types?

A

Epithelial, muscle, cartilage and bone but mostly by fibroblasts

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22
Q

Define soft connective tissue

A

Flexible and gel like - divisible into fibrous or fatty connective

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23
Q

Define hard connetive tissue

A

Forms of bone

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24
Q

Define fibrous connective tissue

A

Contains large numbers of collagen, elastin and reticulin fibres

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25
Q

Define loose irregular fibrous connective tissue

A

Contains few randomly orientated fibres

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26
Q

Define dense irregular fibrous connective tissue

A

Contains large number of fibres with little amorphous material

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27
Q

Define regular dense fibrous connective tissue

A

Fibres arranged in parallel bundles

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28
Q

Define fatty connective tissue

A

Contains mainly fat cells with intervening blood vessels, particularly capillaries

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29
Q

Where are connective tissue cells mainly derived from?

A

Mesenchymal cells

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30
Q

What are the main cell types found in connective tissue?

A

Adipose

Fibroblasts/Fibrocytes

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31
Q

What are the main visible fibres found in connective tissue?

A

Collagen
Elastin
Reticulin

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32
Q

What are the main components of ground substance

A

Proteoglycans
Glycosaminoglycans
Laminin/Fibronectin (Invisible fibres)

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33
Q

Does ground substance stain with H and E?

A

No, appears as white space

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34
Q

What cell type secretes collagen

A

Fibroblasts

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35
Q

What are the type 1 collagens

A

Skin, bone, teeth and organ capsules

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36
Q

What are the type 2 collagens

A

Cartilage

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37
Q

What are the type 3 collagens

A

Liver, bone marrow and spleen

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38
Q

What are the type 4 collagens

A

Basement

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39
Q

What are the type 5 collagens

A

Placenta

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40
Q

Describe the structure of a tropocollagen subunit

A

Three linear polypeptide chains wound together in an alpha helix

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41
Q

Give an example of regular dense connective tissue

A

Tendon

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42
Q

Give an example of irregular dense connective tissue

A

Penile fascia

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43
Q

Describe reticulin

A

type 3 collagen forms supporting scaffold for liver, bone marrow, kidney, spleen and lymph nodes

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44
Q

Is reticulin visible on H and E

A

No, needs a silver stain that makes the collagen appear as black lines

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45
Q

Van Geisons stain will stain elastic fibres and sheets what colour?

A

Dark brown

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46
Q

Describe white adipose

A

Large cells with a single fat globule in each cell and appear as an empty white space

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47
Q

What is the function of white adipose?

A

Protects the vital organs and serves as an energy store

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48
Q

Describe brown adipose tissue

A

found across the shoulders and backs of newborns

Pink foamy appearance

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49
Q

What is the function of brown adipose

A

Thermal regulation - generates heat upon breakdown

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50
Q

Where is cartilage derived from

A

Undifferentiated mesenchymal cells

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51
Q

Describe the structure of cartilage

A

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

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52
Q

What is the fibrous capsule surrounding cartilage called?

A

Perichondrium which contains undifferentiated progenitor cells that can differentiate into chondroblasts

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53
Q

Give an example of a glycosaminoglycans

A

Hyaluronic acid

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54
Q

Give two examples of proteoglycans

A

Chondroitan sulphate

Keratan glycan

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55
Q

Give three types of cartilage

A

Hyaline
Elastic
Fibro

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56
Q

Where is hyaline cartilage found

A

In synovial joints

Rings of the trachea and the cartilage of the larynx

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57
Q

Where is elastic cartilage found?

A

Pinna of the ear

Epiglottis

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58
Q

Where is fibrocartilage found

A

In the annulus fibrosis in the intervertebral discs and in the pubic symphysis

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59
Q

Give three locations of visceral smooth muscle

A

Wall of the intestine
Arterial wall
Bronchioles of the lung

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60
Q

Give three locations of voluntary skeletal muscle

A

Skeletal muscles
Larynx
Diaphragm

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61
Q

Other than muscle name three other contractile cell types

A

Pericytes
Myo-Fibroblasts (Scar formation)
Myo-epithelial cells (Expression of milk during lactation)

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62
Q

Describe the structure of a gap junction

A

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

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63
Q

What are the functions of epithelial cells

A

Protection - skin
Absorption - gut
Secretion - pancreas, liver and GIT

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64
Q

Describe the structure of a simple epithelia

A

Single layer of cells on a basement membrane

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65
Q

What function are simple epithelia associated with?

A

Absorption and secretion

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66
Q

Describe the structure of stratified (Compound) epithelia

A

Two or more layers of cells on a basement membrane

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67
Q

What function is associated with stratified epithelium

A

Protection - found in areas of the body that experience frictional and abrasive forces such as the skin, mouth, throat, oesophagus and vagina

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68
Q

What is the simple squamouss epithelium that lines the blood vessels called?

A

Endothelium

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69
Q

What is the simple squamous epithelium that lines outside the lungs called

A

Mesothelium

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70
Q

What is the simple squamous epithelium that lines abdominal organs called

A

Peritoneum

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71
Q

Describe the structure of simple cuboidal epithelium

A

Single layer of cells with similar height and width on a basement membrane with a central spherical nuclei

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72
Q

Where are simple cuboidal epithelium found?

A

Occur in the ducts of glands such as sweat, salivary and pancreatic (Exocrine glands)

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73
Q

Describe the structure of simple columnar epithelium

A

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

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74
Q

Where are simple columnar epithelium found?

A

Lining the stomach, intestines and uterus

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75
Q

Where are microvilli found?

A

Gut enterocytes

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76
Q

Where are villi found?

A

Respiratory tract

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77
Q

Describe the structure of microvilli

A

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

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78
Q

What stain is used to stain columnar epithelial cells a dark magenta

A

PAS

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79
Q

Describe the structure of cilia

A

0.2um motile projections on luminal surfaces of cells that contain contractile proteins that enable the wafting of mucus

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80
Q

Where are cilia most commonly found?

A

Airways of the nose, larynx, bronchial tree and Fallopian tubes

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81
Q

What is the purpose of keratin?

A

Waterproofs cells

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82
Q

Where is stratified squamous non-keratinising epithelium commonly found?

A

Mouth, oropharynx, oesophagus and vagina (Wet areas)

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83
Q

Where are keratohyaline granules found?

A

At the boundary between living epithelial cells and dead pink keratinising layers

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84
Q

Describe the structure of pseudo stratified epithelium

A

Single layer of cells of variable height mimicking multiple layers but all the cells are in contact with the basement membrane

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85
Q

Where is pseudo stratified epithelium most commonly found?

A

Trachea and the bronchi

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86
Q

How are cells replaced in stratified epithelium

A

Vertical migration

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87
Q

How are cells replaced in pseudo stratified epithelium

A

Lateral migration

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88
Q

Describe the structure of urothelium

A

Looks stratified but there is a surface layer of umbrella cells (3-7layers thick) that is not in contact with the basement membrane

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89
Q

Name two proteins found in the basement membrane?

A

collagen IV

Fibronectin

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90
Q

What are the two types of epithelial junction

A

Occluding (tight) junctions

Desmosomes (Anchoring junctions)

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91
Q

Describe the structure of occluding junctions

A

Band like fusions between cells that are impervious to molecules

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92
Q

Describe the structure of desmosomes

A

Plaques that form physical joins between cells and connect the cytoskeletons of adjacent cells

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93
Q

What is the function of desmosomes

A

To spread mechanical forces across several cells

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94
Q

What do adherent junctions connect

A

Link actin filament network between adjacent cells to the extracellular matrix

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95
Q

What do desmosomes connect

A

Intermediate filament networks of adjacent cells

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96
Q

What do hemidesmosomes connect

A

Intermediate filament network of cells to the extracellular matrix (Basement membrane)

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97
Q

Epithelial cells that secrete protein have what characteristic intrinsic organelles

A

Large nuclei and abundant endoplasmic reticulum

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98
Q

Mucin secreting epithelial cells have what characteristic intrinsic organelles

A

Expanded Golgi system

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99
Q

Steroid secreting epithelial cells have what characteristic intrinsic organelles

A

Smooth endoplasmic reticulum

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100
Q

Define apocrine

A

Secrete by budding

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101
Q

Define endocrine

A

Secrete directly into the blood

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102
Q

Define holocrine

A

releasing a secretion that is the product of the degradation of cell

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103
Q

Define exocrine

A

Secrete by passage of liquid across membranes

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104
Q

What percentage of blood is cellular

A

44%

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105
Q

What percentage of blood is plasma

A

56%

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106
Q

What are the components of plasma

A
Water 
Salt and minerals 
plasma Proteins (Albumin, globulins and fibrinogen)
Hormones and signalling molecules 
Clotting factors
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107
Q

Define blood serum

A

Plasma minus the clotting factors

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108
Q

What stain is used to examine the composition of blood

A

Romanowsky stain

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109
Q

What is the lifespan of a red blood cell

A

120 days

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110
Q

Where are RBC produced

A

Liver (Foetus) and bone haematopoeitic marrow

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111
Q

What is a reticulocyte

A

An immature RBC that still has some ribosome remnants

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112
Q

Describe the structure of RBC

A
Enucleate
Biconcave 
6.5-8.6um in diameter 
Major protein is haemoglobin
Major protein of endoskeleton is spectrin
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113
Q

Where are RBC normally destroyed

A

Liver and spleen

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114
Q

Define a granulocyte

A

Contains visible granules in cytoplasm

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115
Q

Which leucocytes are granulocytes

A

Neutrophils
Eosinophils
Basophils

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116
Q

Define granulocyte

A

No visible granules in the cytoplasm

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117
Q

Which leucocytes are agranulocytes

A

Lymphocytes and monocytes

118
Q

Which leucocyte has a multi-lobed nucleus

A

Neutrophils

119
Q

Which leucocyte has a nucleus and prominent dark blue granules

A

Basophils

120
Q

Which leucocyte has a nucleus and bright pink granules

A

eosinophils

121
Q

Which leucocyte are small cells with dark stained nucleus and little cytoplasm

A

Lymphocyte

122
Q

Which leucocyte has a kidney shaped nucleus

A

Monocyte

123
Q

Describe the properties of neutrophils

A

Most common
Multi lobed nucleus
Granular cytoplasm
12-14um in diameter

124
Q

What is the function of neutrophils

A

Phagocytic (Primary phagocytes)
Engulf and destroy bacteria and foreign macromolecules
Operate in hostile environments (Ie low oxygen tension)

125
Q

What are the three types of cytoplasmic granule found in neutrophils

A

Primary granule
Secondary granule
Tertiary granule

126
Q

Describe primary granules

A

Lysosomes such as myeloperoxidase and acid hydrolase

127
Q

Describe secondary granules

A

Specific granules that secrete substances that mobilise inflammatory mediators

128
Q

Describe tertiary granules

A

Gelatinases that break down proteins and adhesion molecules and help the neutrophil move out the blood vessel and into the tissue

129
Q

Describe the properties of eosinophils

A

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
Q

What is the function of eosinophils

A

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
Q

Describe the properties of basophils

A

0.5% of WBC
14-16um
Dark blue stained cytoplasmic granules that contain histamine

132
Q

What is the function of basophils

A

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
Q

What are the two divisions of lymphocytes

A

B cells

T cells

134
Q

What are B cells

A

Become plasma cells and secrete antibodies

135
Q

Where are B cells formed

A

In the bone marrow

136
Q

What are T cells

A

Involved in cell mediated immunity

137
Q

Where are T cells formed?

A

In the thymus

138
Q

What is the function of T helper cells

A

Help B cells and activate macrophages

139
Q

What is the function of T cytotoxic cells

A

Kill previously marked target cells

140
Q

What is the function of T suppressor cells

A

Suppress the T helper cells and hence suppress the immune response

141
Q

What is the function of natural killer cells

A

Mainly kill virus infected cells

142
Q

Describe the properties of monocytes

A

Kidney shaped nucleus
15-20um diameter
differentiate into one of several cell types

143
Q

What are the 5 types of cell that monocytes differentiate into

A
Tissue macrophage 
Kupffer cells 
Osteoclasts 
Antigen presenting cell 
Alveolar macrophages
144
Q

Describe the properties of platelets

A

Fragments of cells derived from large multinucleate megakaryocytes in bone marrow
1-3um in diameter
Responsible for clotting of blood

145
Q

Define haematopoiesis

A

Formation of blood cells

146
Q

All blood cells are derived from what multipotent haemopoietic stem cell

A

Haemocytoblast

147
Q

What two cells does the haemocytoblast form

A

Common myeloid progenitor

Common lymphoid progenitor

148
Q

What is the precursor cell to leucocytes

A

Myeloblast

149
Q

Define histology

A

Study of microscopic structure of biological material and the ways the components are structurally and functionally related

150
Q

Define cytology

A

Analysis of fine structure of cells by light microscopy

151
Q

Describe how histological slices are produced

A

Tissue preserved in formalin then embedded in paraffin which requires removal of water then 4 micron slices are taken, mounted and stained

152
Q

H and E stains nuclei and cytoplasm what colours

A

Nuclei = blue
Cytoplasm = pink
Extracellular fibres also stain pink
GAG’s appear as white

153
Q

What PAS stain and what colour

A

Sugars - goblet cell in small intestine and GAG’s in intestinal border
stains magenta

154
Q

What does Van Giesons stain and what colour

A

Elastic fibres = brown
Collagen = pinkish-red
Muscle = yellow

155
Q

What does alcian blue stain

A

Mucins secreted by epithelial cells

156
Q

What are the 6 types of cell shape

A
Rounded 
Polygonal 
Fusiform 
Squamous 
cuboidal 
columnar
157
Q

Why are some cells smaller with less cytoplasm and smaller nuclei?

A

Because the are metabolically inactive or dormant

158
Q

Which cells tend to have elaborate cell machinery and nucleoli specialised for DNA transcription?

A

Metabolically active cells

159
Q

Which cell types have a lifespan of days

A

Cells lining the gut

160
Q

Which cells have a lifespan of months

A

Blood (120days)
Skin
Connective tissue

161
Q

Which cells have a lifespan of years

A

Bone and tendon

162
Q

Which cells have a lifespan of nearly a whole life

A

Skeletal muscle

163
Q

Which cells last your whole life

A

Nerve and brain
Cardiac
Germ cells

164
Q

Name the 6 membranous organelles

A
Nucleus 
Lysosome 
Mitochondria 
Peroxisome 
Golgi 
Endoplasmic reticulum
165
Q

Name the 4 non-membranous organelles

A

Ribosomes
Centrosomes
Centrioles
Basal bodies

166
Q

What is the nuclear lamina

A

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
Q

Darker areas of the nucleolus consist of what sort chromatin

A

Heterochromatin

168
Q

Lighter areas of the nucleolus consist of what sort of chromatin

A

Euchromatin

169
Q

What is the size and function of the nucleolus

A

1-3 microns in diameter and acts as the site of ribosomal RNA formation

170
Q

What are the three different regions of the nucleolus

A
Pars Amorpha (Pale areas)
Pars Fibrosa (Dense stain regions)
Pars Granuloase (Granular regions)
171
Q

What is the function of the pars amorpha

A

Contain specific RNA binding proteins and correspond to large loops of transcribing DNA containing ribosomal RNA genes

172
Q

What is the function of the pars fibrosa

A

Correspond to the transcripts of ribosomal RNA genes beginning to form ribosomes

173
Q

What is the function of the pars granulosa

A

Correponds to RNA containing maturing ribosomal particles

174
Q

What is the function of the pars granulosa

A

Correponds to RNA containing maturing ribosomal particles

175
Q

Describe the structure of chromatin

A

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
Q

What does euchromatin represent

A

Light stained areas with unwound chromatin that is actively transcribed into cellular DNA

177
Q

What does heterochromatin represent

A

Dense stained areas that are highly condensed and transcriptionally inactive

178
Q

What is the outer membrane of mitochondria associated with

A

Lipid synthesis

Fatty acid metabolism

179
Q

What is the inner membrane of mitochondria associated with

A

Respiratory chain (ATP production)

180
Q

What is the matrix of mitochondria associated with

A

TCA cycle

181
Q

What is the inter membranous space of the mitochondria associated with

A

Nucleotide phosphorylation

182
Q

Function of RER

A

Protein synthesis

183
Q

Function of SER

A

Lipid synthesis

184
Q

Function of golgi

A

Synthesises steroids and other lipids

Detoxifies alcohol and drugs

185
Q

Describe the cis face of the Golgi apparatus

A

Nuclear facing

Receives transport vesicles from the SER and phosphorylates some proteins

186
Q

Describe the medial face of the Golgi apparatus

A

Central part that forms oligosaccharides by adding sugars to lipids and peptides

187
Q

Describe the trans golgi network

A

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
Q

Describe the structure of lysosomes

A

Intracellular digestion system

H+-ATPase on membrane creates low internal pH and also contains acid hydrolyases which degrade proteins

189
Q

Describe the structure and function of peroxisomes

A

Membrane bound organelles which oxidise long chain fatty acids by producing H2O2 - neutralise free radicals, detoxify alcohols and other drugs

190
Q

What is the function of cytoskeleton

A

Determines cell shape, structure, organises cell contents and directs the movement of materials in the cell

191
Q

What are the three main protein filaments found in the cytoskeleton

A

Microfilaments
Microtubules
Intermediate fibres

192
Q

Describe the properties of microfilaments

A
smallest fibre (5nm) 
Made of actin which forms a bracing mesh on the inner surface of cell membrane to maintain cell shape
193
Q

Describe the properties of microtubules

A

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
Q

Describe the properties of intermediate filaments

A

10nm in diameter
6 different types
Anchored to the transmembrane proteins and spread tensile forces throughout the tissues

195
Q

What are the 6 types of intermediate filament

A

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
Q

What is lipofuscin

A

Membrane bound orange brown pigment

197
Q

Define transmission electron microscope

A

Resolution of sub cellular structures in thin tissue sections

198
Q

Define scanning electron microscope

A

Resolution of three dimensional sub cellular structures

199
Q

What are the three layers of the cardiac muscle

A

Myocardium
Epicardium
Pericardium (Outermost)

200
Q

Describe the structure of cardiac muscle

A

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
Q

Where are the largest myocytes found

A

Wall of the left ventricle

202
Q

Describe the structure of cardiac valves

A

Covered by endothelium and consist of thick collagen fibres with some elastic tissue
Free margins are connected to papillary muscles by chord tendinae

203
Q

What are the three layers found in cardiac valves

A

Fibrosa (Dense fibrous CT)
Spongiosa (Loose fibrous CT)
Ventricular (Collagen and elastin)

204
Q

Where are the nodules of arantius found

A

In aortic valve cusps

205
Q

Describe skeletal muscle

A

Striated
Nucleus at edge
No branching

206
Q

describe cardiac muscle

A

Striated
Central nucleus
Branching

207
Q

Describe smooth muscle

A

Not striated
Central nuclei
No branching

208
Q

What are the 8 functions of the respiratory tract

A
Air filtration 
Humidification 
Warming inspired air 
Olfaction 
Protection from infection 
Speech 
Gas transport 
Gas exchange
209
Q

What epithelium lines the conducting airways

A

Simple or pseudo stratified columnar ciliated epithelium punctuated with mucus secreting goblet cells

210
Q

What are the functions of the nose

A

Warming
Filtration
Humidification
Olfaction

211
Q

What epithelium lines the root of the nasal cavity (Cribriform plate)

A

Pseudostratified columnar epithelium of olfactory receptor cells with supporting sustentacular cells and basal cells

212
Q

What are the functions of the nasopharynx

A

Gas transport
Humdification
warming o
olfaction

213
Q

What epithelium lines the nasopharynx

A

Respiratory epithelium

214
Q

What are the function of the nasal sinuses

A

Lower weight of the skull
Add resonance to the skull
Humidify and warm inspired air

215
Q

What epithelium lines the nasal sinuses

A

Respiratory epithelium

216
Q

What epithelium lines the larynx

A

Respiratory epithelium except the vocal chords which are lined by a stratified squamous

217
Q

What epithelium covers the vocal chords

A

Stratified squamous overlying a loose irregular fibrous tissue (Reinke’s Space)

218
Q

Which epithelium covers the trachea

A

Respiratory epithelium

219
Q

Describe the histology of the main, lobar and segmental bronchi

A
Smooth muscle 
Partial cartilaginous rings 
Respiratory epithelium 
Some basal neuroendocrine cells 
Seromucinous glands and goblet cells
220
Q

Describe the histology of the bronchioles

A
Smooth muscle 
Ciliated columnar epithelium 
Some basal neuroendocrine cells 
Few goblet cells 
Clara cells
221
Q

Where are Clara cells most numerous

A

Terminal bronchioles

222
Q

What are the functions of Clara cells

A

Oxidise inhaled toxins
Antiprotease function
Surfactant production/Elimination
Stem cell function

223
Q

Describe the structure and properties of type I pneumocytes

A

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
Q

Describe the structure and properties of type II pneumocystes

A

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
Q

Describe the structure and function of alveolar macrophages

A

Phagocytic cells derived from blood monocytes found in the interstitial connective tissue of alveolar walls
Phagocytose particulates including ducts and bacteria

226
Q

What is the purpose of pores Kohn and why are they potentially problematic

A

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
Q

What epithelium lines the oral cavity

A

Non keratinised stratified squamous epithelium

228
Q

What epithelium lines the oesophagus

A

Stratified squamous with submucosal glands which secrete mucus onto surface to help lubricate food

229
Q

What are the 4 layers of the gut wall from innermost to outermost

A

Mucosa
Submucosa
Muscularis propria
Serosa

230
Q

Which cells are responsible for the nervous control of the smooth muscle of the gut and where are they found

A

Ganglion cells

Found in the muscularis propria between the longitudinal and circular muscle layers

231
Q

What is the function of the interstitial cells of Cajal

A

Pacemakers of contraction in the GIT

232
Q

Describe the layers of the gut wall

A
Epithelium
Basement membrane 
Lamina propria 
Muscularis mucosae
Submucosa
Inner circular layer (Muscularis propria)
Outer longitudinal layer (Muscularis Propria)
Adventitia (Serosa)
233
Q

Describe the layers of the stomach wall

A
Epithelium
Basement membrane 
Lamina propria 
Muscularis mucosae 
Submucosa
Inner oblique, middle circular and outer longitudinal layers of the muscularis propria
234
Q

What is the epithelium lining the lips

A

Non keratinised stratified squamous epithelium

235
Q

What is the epithelium of the skin around the lips

A

Keratinised stratified squamous epithelium

236
Q

What is the epithelial covering of the tongue

A

Converted by non-keratinised stratified squamous epithelium on ventral surface and keratinised on its dorsal surface

237
Q

What is the name of the V-Shpaed row of papillae that separate the anterior 2/3 and posterior 1/3 of the tongue

A

Circumvallate papillae

238
Q

Where are fungiform papillae found

A

Tip and sides of the tongue

239
Q

Where are filiform papillae found

A

Cover whole anterior 2/3 of tongue

240
Q

What epithelium lines ducts of the parotid acini

A

Simple cuboidal epithelium

241
Q

What epithelium lines the epiglottis

A

Stratified squamous epithelial that becomes respiratory epithelium at the beginning of the respiratory tract

242
Q

Describe the muscle types found in the oesophagus

A

Skeletal muscle at the proximal end but smooth muscle at the distal end

243
Q

What is the epithelial lining of the stomach

A

Simple columnar epithelium punctuated by gastric pits

244
Q

How does the muscular propria layer differ in the gut tube and stomach

A

Stomach has three layers compared to the guts two in order to help churn food

245
Q

Where in the stomach are full gastric glands found

A

Body and fundus

246
Q

How do glands found in the pylorus and cardia of the stomach differ from the full gastric glands

A

devoid of parietal and chief cells

247
Q

Describe the structure of parietal cells

A

Found in gastric glands of body and fundus and occupy upper parts of these glands - are globular in shape and stain bright pink

248
Q

Describe the structure of chief cells

A

Pyramidal in shape and occupy deeper parts of the gland

Cytoplasm stains blue with H and E

249
Q

How do gastric glands in the cardiac and pylorus regions of the stomach differ from those in the fundus and body of the stomach

A

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
Q

What are the lymphatics in villi called

A

Lacteals

251
Q

What type of epithelia covers the villi and what are the main two cell types interspersed in the epithelia?

A

Simple columnar epithelia
Enterocytes (Absorptive cells)
Goblet cells (Mucus secreting)

252
Q

What lies between the villi?

A

Straight tubular glands called crypts of Liberkuhn that contain a stem cell population to replace villi cells

253
Q

What is the functional importance of the glycocalyx found at the brush border of enterocytes

A

Acts as a filter and as an anchorage for exo-enzymes

254
Q

What glands lie in the submucosa of the duodenum and what are their functions

A

Brunner’s Gland which secretes alkaline substance that helps to neutralise chyme entering the stomach

255
Q

Where do newly formed enterocytes from crypts go in the small intestine

A

Migrate onto the villi

256
Q

Where do newly formed enterocytes from crypts go in the large intestine?

A

Spread out on to the flattened surface of the gut

257
Q

What are Paneth cells? where do they lie and what is their function? How can they be identified

A

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
Q

Describe the histology of the vermiform appendix

A

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
Q

What epithelium lines the colon and the rectum

A

Simple columnar epithelium

260
Q

What epithelium lines the anal Canal

A

Stratified squamous that becomes keratinised at the distal end

261
Q

What are the 5 main functions of the liver

A

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
Q

Describe the structure of a liver lobule

A

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
Q

Is the oxygenation of hepatocytes equal

A

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
Q

What are the three surfaces of an individual hepatocyte

A

Sinusoidal (70%) - Exchange of material with blood (Space of Disse)
Canalicullar (15%) - Excretion of bile
Intracellular (15%) - Hepatocyte to hepatocyte

265
Q

Where are hepatic stellate cells found

A

Space of disse

266
Q

What is the name of macrophages in the lining of the sinusoid epithelium and what is their function

A

Kupffer cells - phagocytose and destroy blood borne pathogens, produce bilirubin

267
Q

What stain is used to show Kupffer cells

A

Perl’s Stain

268
Q

What epithelium lines the billiary tree

A

Cuboidal epithelium which in smaller vessels is single layered but towards the distal end it becomes stratified

269
Q

What epithelium lines the gall bladder

A

Simple columnar epithelium thrown into folds with microvilli on luminal surface to enable water and salt absorption

270
Q

Exocrine parts of the pancreas account for what percentage of the total gland

A

90%

271
Q

List the duct system that secretions of the acing pancreatic cells drain into from first to last

A

Centroacinar duct
Intercalated duct
Interlobular duct
Main pancreatic duct

272
Q

define endocrine gland

A

Secretes hormones into the bloodstream for circulation around the body

273
Q

What are the 4 types of hormone

A
  1. Derived from AA (Adrenaline)
  2. Small peptides (Vasopressin)
  3. Proteins (Insulin)
  4. (Testosterone)
274
Q

What is the origin of the posterior pituitary

A

Neuronal origin - down growth of the brain that is joined by the pituitary stalk to the median eminence of the midbrain

275
Q

What nuclei are found in the posterior pituitary

A

Supraoptic

Paraventricular

276
Q

What is the origin of the anterior pituitary

A

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
Q

Define portal system

A

One that starts and ends with capillaries

278
Q

Describe how the pituitary portal system works

A

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
Q

What are the 5 main classes of anterior pituitary hormone?

A
Somatotrophs (GH)
Lactotrophs (PRL)
Corticotrophs (ACTH)
Thyrotrophs (TSH)
Gonadotrophs (FSH and LH)
280
Q

What is the name given to cells that secrete growth hormone and prolactin

A

Sommatomammotrophs

281
Q

What are the three groups that anterior pituitary cells were previously classified into

A

Stain heavy with acid (Alpha cells/Acidophils)
Stain heavy with basic dyes (Beta cells/basophils)
Stain weakly with either dye (Chromophobes)

282
Q

What do herring bodies in the posterior pituitary contain

A

Dark stained neurosecretory granules (Oxytocin or vasopressin) bound to a carrier protein (Neurophysin)

283
Q

What is the pars tuberalis

A

Upward extension of the anterior pituitary lobe that surrounds the pituitary stalk to form the puberal lobe which contains mostly gonadotrophin cells

284
Q

What is the function of the pineal gland

A

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
Q

What two hormones does the thyroid gland secrete

A

Thyroxine and calcitonin

286
Q

Describe the structure of thyroid follicles, what do they secrete?

A

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
Q

Describe the process of follicular phases

A

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
Q

What happens the cuboidal epithelium during the active follicular phases of the thyroid

A

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
Q

Where are C cells of the thyroid found and what do they produce

A

Found in clumps between follicles (Parafollicular) and produce calcitonin

290
Q

What are the cells of the parathyroid gland

A

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