Histology Flashcards

1
Q

The plasmalemma is known by which other name?

A

Cell membrane

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2
Q

Many proteins are anchored into the cell membrane, what functions may they have?

A
  • Receptors
  • Enzymes
  • Channels
  • Transporters
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3
Q

What are the three types of filaments that make up the cytoskeleton of a cell?

A
  1. Microfilaments
  2. Intermediate filaments
  3. Microtubules
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4
Q

What are the smallest type of filaments that make up the cytoskeleton?

A

Microfilaments

(approx 7nm diameter)

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5
Q

Microfilaments are composed of what?

A

Actin

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6
Q

There are more than 50 classes of intermediate filaments, what can each class give an indication of?

A

Origin of the cell in the body

(this can help when locating tumours)

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7
Q

What are microtubules composed of?

A

Alpha and beta tubulin subunits

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8
Q

Which two proteins can use microtubules as a transport network and which direction does each travel?

A
  • Kinesin - An ATPase that transports compounds towards the cell periphery
  • Dynein - An ATPase that transports compounds towards the cell centre
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9
Q

The nucleus is surrounded by an _______ and ________ membrane

A

Inner and outer

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10
Q

The outer membrane of the nucleus shares a common border with what?

A

The rough endoplasmic reticulum

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11
Q

What is between the inner and outer nuclear membranes?

A

Perinuclear cisterna

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12
Q

There are three types of RNA, which two are transcribed and which is transcribed in the nucleolus

A

Nucleus - mRNA, tRNA

Nucleolus - rRNA

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13
Q

The nucleus contains two states of DNA, what are these states?

A
  1. Heterochromatin - DNA condensed and not undergoing transcription
  2. Euchromatin - DNA untwisted and undergoing transcription
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14
Q

Where are ribosomes formed?

A

Nucleolus

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15
Q

What two subunits make up a ribosome?

A
  1. Small subunit - binds to mRNA
  2. Large subunit - catalyses formation of peptide bonds
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16
Q

What are the two types of endoplasmic reticulum?

A
  1. Rough
  2. Smooth
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17
Q

What are polysomes?

A

Clusters of free ribosomes in the cytoplasm surrounding mRNA which is being transcribed

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18
Q

What is the role of the smooth endoplasmic reticulum?

A

Processing proteins after passage through the rough endoplasmic reticulum and also for the synthesis of lipids

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19
Q

What is the role of the rough endoplasmic reticulum?

A

The synthesis of membrane bound proteins or secretions.

It is also the site of glycoprotein formation

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20
Q

What is the role of the golgi apparatus?

A

The pakaging and processing of proteins for export to their destinations

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21
Q

The golgi apparatus is made up of many flattened sacs resembling plates, what is each sac called?

A

A Cisterna

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22
Q

How do proteins arrive at the golgi apparatus?

A

In transport vesicles from the smooth endoplasmic reticulum

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23
Q

What is the inner membrane of mitochondria called?

A

The cristae

This is folded to increase surface area

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24
Q

DNA can be found in which two locations within a cell?

A
  1. Nucleus
  2. Mitochondria - they have their own DNA
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25
Q

Which type of muscle will have many mitochondria and which type will have few?

A
  • Many mitochondria - Slow twitch muscle - generally aerobic
  • Few mitochondria - fast twitch muscle - generally anaerobic
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26
Q

What are intercellular junctions?

A

Structures specilaised to join cells into groups to form a functional unit

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27
Q

Where are intercellular junctions most prominent?

A

Epithelial cells

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28
Q

What are the three types of intercellular junctions?

A
  1. Occluding
  2. Anchoring
  3. Communicating
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29
Q

Occluding junctions can have which other name?

A

Tight junctions

(or zonula occludens)

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30
Q

What do occluding junctions function to do?

A

Link cells together to form a diffusion barrier

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31
Q

What are the three types of anchoring intercellular junctions?

A
  1. Adherent
  2. Desmosomes
  3. Hemidesmosomes
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32
Q

Describe the function of anchoring adherent intercellular junctions

A

Actin in the cytoplasm is used to link adjacent cells together

Actin is bound to cadherin - a transmembrane protein which acts as an adhesive linking cells together

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33
Q

Describe the function of anchoring desmosome intercellular junctions

A

Intermediate filaments are used to join cells as they can bind with transmembrane proteins.

This can provide stablity in the skin

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34
Q

Describe the function of anchoring hemidesmosome intercellular junctions

A

Intermediate filaments are linked directly to the extracellular space with the help of transmembrane proteins which can anchor the filaments in place

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35
Q

What is a junctional complex?

A

This is when many types of junctions are used in close proximity

This is common in epithelial cells

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36
Q

Communicating junctions have what other name?

A

Gap junctions

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37
Q

What are communicating junctions composed of?

A

A circular patch with many pores created by connexion proteins which make direct channels between cells

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38
Q

Communicating junctions allow for what between connected cells?

A

Selective diffusion and transfer of certain molecules

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39
Q

Communicating junctions are common in which tissue types?

A
  • Smooth muscle
  • Cardiac muscle (spread of excitation)
  • Epithelial cells
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40
Q

There are 3 main ways in which substances can be transported across a membrane, what are these?

A
  • Diffusion
  • Protein pumps/channels
  • Endo/exocytosis using vesicles (vesicular transport)
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41
Q

During endocytosis, material in the ___________ space can be engulfed by the cell forming an __________

A

Extracellular

Endosome

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42
Q

What is it called when a phagosome and lysome fuse?

A

A phagolysosome

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43
Q

When tissue is prepared for microscopy which chemical may be used to cross link proteins and maintain structure?

A

Formalin

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44
Q

What is added to tissues to give it structure before it is used for microscopy?

A

Wax

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45
Q

What is a common dye used to allow differentiation in different cell parts?

A

“H & E”

  • Haematoxylin (H) - a basic dye which binds to acidic molecules such as DNA or ribsomes causing a purple colour
  • Eosin (E) - an acidic dye which binds to basic molecules such as cytoplasmic proteins causing a pinkish colour
46
Q

What are the four basic tissue types?

A
  1. Epithelium
  2. Connective tissue
  3. Muscle
  4. Nervous
47
Q

What is the basal lamina?

A

The extracellular matrix of components at the basal (underside) surface of epithelial cells.

48
Q

Which type of cells are not vascularised and how do they aquire nutrients?

A

Epithelial cells

They acquire nutrients via diffusion from the basal lamina

49
Q

What are the different epithelial cell shapes?

A
  • Squamous (flat)
  • Cuboidal (cube shaped)
  • Columnar (cuboidal - tall and thin)
50
Q

What are the names of epithelia based on the number of layers?

A
  • One - simple
  • Two or more - stratified
  • Multiple layers - pseudostratified (all cells in contact with the basal lamina)
51
Q

What are the two types of epithelial gland?

A
  1. Endocrine (ductless) - product secreted towards the basal end of the epithelium and distributed into the vascular system - lots of capillaries will surround the glands
  2. Exocrine (ducted) - product secreted upwards towards the apical end of an epithelial cell
52
Q

What are the three subtypes of connective tissue?

A
  1. Soft connective tissue
  2. Hard connective tissue
  3. Blood and lymph
53
Q

What are fibroblasts?

A

Cells that are widely distributed in the extracellular matrix helping to maitain it

54
Q

What are chrondrocytes?

A

Cartilage cells

55
Q

Within the extracellular matrix there is ground substance, what is this?

A

A large space containing a gel-like substance made of huge polysaccharide molecules called glycosaminoglycan which are mostly bound to protein cores to form glycoproteins

56
Q

What are the two types of soft connective tissue?

A
  1. Dense regular - densely pack collagen fibres in ordered alignment
  2. Dense irregular - densely packed collagen fibres running in many directions which resists breakage
57
Q

What allows cartilage to be flexible?

A

The ground substance in cartilage is very hydrated allowing for this type of flexible stucture

58
Q

How does cartilage receive nutrients since it is not vascularised?

A

Diffusion through its matrix

59
Q

What are the three types of cartilage?

A
  1. Hyaline
  2. Elastic
  3. Fibrocartilage
60
Q

What are the two types of bone which are distinct to the naked eye?

A
  1. Cortical bone - outer shell composing the shaft (diaphysis)
  2. Cancellous (trabecular) bone - inside of bone, an interconnected network of bone fragments that contains small holes and hollow sections
61
Q

What are osteocytes?

A

Bone cells

62
Q

What are the three major types of muscle tissues?

A
  1. Smooth (involuntary)
  2. Skeletal (voluntary)
  3. Cardiac
63
Q

What causes skeletal muscle striations?

A

The overlapping of actin and myosin filaments

64
Q

What joins cardiac muscle cells together?

A

Intercalated discs

(gap junctions are common between cells)

65
Q

Neurones in the CNS and PNS have a coating around them, what is this coating called in each area?

A
  1. CNS - Meniges
  2. PNS - Epineurium
66
Q

Depending on the way the cell body is attached, neurones fall into which three categories?

A
  1. Unipolar - cell body attached in one place
  2. Bipolar - cell body attached in two places
  3. Multipolar - cell body attached in many places
67
Q

What are the three types of glia?

A
  1. Astrocytes
  2. Oligodendrocytes
  3. Microglia
68
Q

What is the function of astrocytes?

A

Provide support and contribute to ion transport

They also play a role in tissue repair after damage and aid by producing scar tissue by secreting the contents of their extracellular matrix

69
Q

What is the role of oligdendrocytes?

A

To produce myelin

70
Q

Microglia have what function?

A

To provide immune surveillance

71
Q

What is the principle glia of the PNS and what is its function?

A

Schwann cells

Produce myelin and support the axons

72
Q

Striated ducts are present in salivary ducts, what is their function?

A

They actively pump salt ions out of saliva ensure saliva remains hypotonic to red blood cells preventing water from inside red blood cells flowing into the saliva

73
Q

What are the four layers of the digestive tract outwards from the lumen?

A
  1. Mucosa
  2. Submucosa
  3. Muscularis externa
  4. Serosa
74
Q

What is the mucosa in the digestive tract composed of?

A
  • Epithelium - sits on the basal lamina
  • Lamina propria - loose connective tissue
  • Muscularis mucosae - thin layer of smooth muscle
75
Q

What is the submucosa in the digestive tract composed of?

A

Loose connective tissue

76
Q

What is the muscularis externa composed of in the GI tract?

A

Two thick layers of smooth muscle

  • Inner circular layer
  • Outer longitudinal layer
77
Q

What is the serosa in the GI tract composed of?

A

Connective tissue

(can suspend or attach the digestive tract to other organs)

78
Q

The outer longitudinal layer of muscle in the muscularis externa within the GI tract is not continuous, but instead found in 3 strips called what?

A

Teniae coli

79
Q

What is the enteric nervous system?

A

The nervous system of the digestive tract allowing it to function independently with input from the autonomic nervous system

80
Q

Within the liver, what comprised a portal triad?

A
  1. Hepatic portal vein
  2. Hepatic artery
  3. Bile duct
81
Q

What does the exocrine pancrease function to do?

A

Produce digestive juices containing proteases and other breakdown enzymes as well as lipases and nucleases

82
Q

What is the function of the endocrine pancreas?

A

It is covered in many receptors (islets of Langerhans) which produce hormones insulin and others to regulate blood sugar levels

83
Q

What percentage of blood is composed of cells?

A

45%

84
Q

What percentage of the cells within blood are red blood cells are what percenatge are white blood cells?

A

Red - 99%

White - 1%

85
Q

What are the five main types of lymphocytes found in blood?

A
  1. Neutrophils
  2. Lymphocytes
  3. Monocytes
  4. Basophils
  5. Eosinophils
86
Q

Arteries are made up of what three layers?

A
  1. Tunica intima
  2. Tunica media
  3. Tunica adventitia
87
Q

In artery walls, the tunica media and tunica adventitia are separated by what type of membrane?

A

External elastic membrane

88
Q

The walls of capillaries are composed of what?

A

Endothelial cells and a basal lamina

89
Q

Why do veins have a wider lumen when compared with arteries?

A

They carry blood at a lower pressure

90
Q

What factors aid the movement of lymph around the body?

A
  1. Smooth muscle in the walls of the body
  2. Hydrostatic pressure
  3. Compression of vessels by skeletal muscle contraction
91
Q

Elastic arteries are so thick-walled that they require have their own blood supply, which vessels supply there arteries?

A

Vaso vasorum arteries

92
Q

A capillary bed is made up of a network of what?

A
  • Metarterioles
  • Throughfare channels
  • Capillaries
  • Precapillary sphincters
93
Q

What are pericytes?

A

Cells that surround the basal lamina or capillary endothelial cells

They have stem cell properties yet mostly aid contraction

94
Q

What are the three types of capillaries?

A
  1. Continuous
  2. Fenestrated
  3. Sinusoidal
95
Q

Describe continuous capillaries

A

They are found inmuscle, nerve, lung and skin tissue

They are the least permeable of all capillaries and have intact walls

96
Q

Describe fenestrated capillaries

A

They have small pores in their walls allowing larger molecules to pass though.

Commonly found in the gut mucosa, endocrine glands and the kidney

97
Q

Describe sinusoidal capillaries

A

They have large gaps are are discontinuous

They are found in the liver, spleen and bone marrow

98
Q

What do capillary networks drain into?

A

Post-capillary venules

99
Q

At which point is a capillary termed a venule?

A

As soon as there is smooth muscle in the walls

100
Q

Why do the largest veins have a thich layer of tunica adventitia?

A

It aids in the support of a physically larger structure

101
Q

What two different classes of white cells are found in the blood?

A
  1. Granulocytes
  2. Agranulocytes
102
Q

What is the average lifespan of a red blood cell?

A

120 days

103
Q

Old red blood cells are removed from circulation by which two organs?

A

Liver and spleen

104
Q

What is the most abundent white cell in the blood?

A

Neutrophil

105
Q

Eosinophils stain well with what dye?

A

Eosin (a red acidic dye)

106
Q

Basophils stain well with which dye?

A

Basic dyes

(methylene blue)

107
Q

Where does erythrocyte formation firstly occur?

A

Yolk sac during embryonic development

(after around 3 weeks of gestation)

108
Q

At birth, what area of the body becomes the area of red blood cell formation?

A

Bone marrow

In adulthood only vertebrae, ribs, skull and proximal femurs retain haemopoiesis - the ability to produce red blood cells

109
Q

What is an erythrocyte termed after RNA granules appear in its cytoplasm?

A

Reticulocyte

110
Q

Describe the steps in the pathway of erythrocyte development

A
  1. Proerythroblast
  2. Basophilic erythroblast (early normoblast)
  3. Polychromatic erythroblast (intermediate normoblast)
  4. Orthochromatic erythroblast (late normoblast)
  5. Reticulocyte erythroblast
111
Q

What are megakaryocytes?

A

Huge cells that allow for platelet formation

Plateletes will bud off from small sections of the cytoplasm

112
Q

What happens to a megakaryocyte after many platelets have been produced from it?

A

It will undergo apoptosis