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Histology Flashcards

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1
Q

What is the composition of a cell?

A 
80% water
15% protein
2.5% lipid
1.5% carbohydrate
1.1% inorganic
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2
Q

Embryonic cells have more water than old cells. T of F?

A

True

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3
Q

What makes up the cytoskeleton?

A

Mictofillaments
Microtubles
Intermediate fillaments

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4
Q

What is a microfilament?

A

Fine strands of actin which assemble into filaments and then dissociate (dynamic )
Fillamentous actin

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5
Q

What are microtubles?

A

Hollow
Composed of alpha and beta tubulin subunits
Can be assembled and disassembled
Initiate from a centromere and cnntain stabilising proteins
Polar- originate in the centre and radiate outwards

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6
Q

What are the functions of microtubules?

A

Cilia, flagella and mitotic spindles

Transport between membranes organelles and vesicles

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7
Q

Give 2 ATPases used to move things along microtubules?

A

Kinesin- moves things towards the periphery

Dynein- moves things towards the cell centre

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8
Q

What is the goli complex?

A

Flatterened membrane bound cicternaewith sub compartments

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9
Q

What is the function of the colgi complex

A

Vesicles arrive at the CIS face from SER/RER
Modify and pack macromolocules by adding sugar, splitting protein and sorting
Vesicles are emmitted from the TRANS face

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10
Q

What are intermediate fillaments?

A

A class of over 50 proteins wwhich bind intracellular elements to gather and to the plasma lemma

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11
Q

Where are the following intermediates found?

a) Neurofillaments
b) Glial fibrillary acidic proteins
c) desmin
d) Cytokeratins
e) vimentin
f) Filesin
g) lamin

A

a) Neurofillaments = nerve cells
b) Glial fibrillary acidic proteins = glial cells
c) desmin= muscle cells
d) Cytokeratins= Epithilial cells
e) vimentin = mesenchymal cells (connective tissue)
f) Filesin = Lens of the eye
g) lamin = nuclei of all cells
NB: can be used to identify the origins of tumours

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12
Q

How is the nucleus enclosed?

A

Nuclear envolope with an inner and outer nuclear membrane with nuclear pore

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13
Q

What is found between the nuclear membranes?

A

Perinuclear cistern which is continuous with the cistern of ER

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14
Q

What does the outer nuclear membrane extend to form?

A

ER and has ribosomes

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15
Q

What is contained within the nucleus?

A

DNA on chromosomes

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16
Q

WHat are the 2 types of chromosomes?

A

Euchromatin- DNA more dispersed and actively undergoing transcription
Heterochromatin- high condensed DNA not undergoing transcription

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17
Q

Where is tRNA and mRNA transcribed?

A

In the nucleus

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18
Q

Where is rRNA transcribed?

A

Nucleolus

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19
Q

What are inclusions?

A

Dispensable and transient

Vesicles containing components either synthesised by the cell or taken up form the ECF

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20
Q

What is an intercellular or occluding junction and what is its function?

A

Tight junction which appears as a focal region of close proximity between adjacent cell membranes
Prevent diffusion

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21
Q

What is a communicating junction?

A

Gap junction
A circular patch with hundreds of pores
Close association of cells

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22
Q

What forms the pores in gap junctions?

A

Connexion proteins

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23
Q

What is the function of communicating junctions?

A

Allow selective diffusion of molecules between adjacent cells

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24
Q

What are the 2 types of anchoring junctions?

A

Adherent junctions

Desmosomes

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25
What forms adherent junction?
Transmembrane cadherin molecules bind to each oter in the extracellular space and through link molecules to the actin of the cytoskeleton
26
What is the function of adherent junctions?
Link sub actin bundles between adjacent cells
27
What is the function of desmosomes?
``` Link sub membrane intermediate fillaments of adjacent cells Mechanical support (skin) ```
28
How are desmosomes formed?
Using desmocollin and desmoglein
29
Why do the membranes spread out in anchoring junctions?
To allow for extracellular membrane proteins and their binding in the extra cellular space
30
What are the characteristics of the plasma lemma?
Amphipathic phospholipid molecules Contain peripheral and integral proteins Cholesterol adds strength Can endo and exo cytose materia Fluid- membrane proteins can diffuse laterally but many are anchored in place Selectively permeable Trilaminar appearance
31
Where are ribosomes formed?
Nucleolus
32
What is the sanction of the small and large subunit in a ribosome?
Smallbinds to mRNA | Large cataylses a peptide bond
33
What is a junctional complex?
Close association of several types of junction. Found in epithilial tissue
34
What is the function of the RER?
Synthesing proteins for insertion into the membrane (initiates glycoprotein formation)
35
What is the function of SER?
Continues processing of proteins form the RER. SIte of lipid synthesis
36
Where are proteins for the cytosol produced?
Free flating polysomes containing ribosomes in the cytoplasm
37
What are the functions of mitochondria?
Respiration and oxiadtive phosphorylation Synthesise cirtain lipids and proteins Contain there own DNA for lipid and protein production
38
What are the 3 salivary glands?
Parotid, submandibular and sublingual
39
What type of glands are the salivary glands?
Exocrine glands as there are many ducts
40
What secretions are made by the salivary glands?
Serous (water and enzymes | Mucus
41
What characterises the parotid gland?
Almost all serous secreting cells Long duct as watery solution will travel further Located furthest from the oral cavity
42
What characterises the sublingual gland?
Mostly mucus secreting cells | Shorter ducts, closer to the oral cavity
43
What characterises submandibular gland?
Secretes mucus and serous | Located at a middle distance from the oral cavity
44
What cells make up salivary glands?
Epithilial cells
45
What are the salivary ducts striated?
Mitochondrial arrangement which provide ATP for molecular pumps in the membrane. They modify saliva by removing salt so saliva is hypotonic to blood
46
What are the 3 layers of the digestive tract proper?
Mucosa - epithilium, lamina propria (lose connective tissue) and muscularis mucosa SUbmucosa- loose connective tissue Muscularis externa- longitudinal and circular muscle layers Serosa or Adventitia- outer later of connective tissue
47
What is the protective epithilium in the GI tract and where is it found?
Non keratitinised stratified squamous epithilium | Found in the oral cavity, pharynx, oesophagus and anal canal
48
What is the secretory epithilium in the GI tract and where is it found?
Simple columnar epithilium with many tubular glands | Stomach
49
What is the absorptive epithilium in the GI tract and where is it found?
Simple columnar epithilium with villi and tubular glands | Small intestine
50
What is the protective and absorptive epithilium in the GI tract and where is it found?
Simple columnar epithilium with tubular glands | Large intestine
51
Where are the neurons found in the GI tract?
In ganglia between the circular and longitudinal muscle layers of the muscularis externa
52
What are the 3 layers of tissue in the tracheal walls?
Respiratory epithilium- produce mucus and cilla Lamina propria- lose connective tissue Hyaline cartilage- tracheal ring
53
What is the difference between bronchi and bronchioles?
Bronchi have hyaline acartilage in walls and bronchioles have smooth muscle
54
How does the columnar epithilium change as you go further down the respiratory tree?
Gets shorter
55
What type of cell lines alvioli?
Simple squamous epithilial cells
56
What type of cells make up the liver?
Mostly epithilial but some connective tissue
57
What arrangement are liver lobules?
Hexagonal
58
Each lobulue has what?
A branch of the hepatic artery, hepatic portal vein and billary duct Portal triad
59
In the liver, what does blood travel from the periphery to the centre in?
Hepatic sinusoids passing sheets of cells called hepatocytes
60
What is a sinusoid?
A space for blood to flow
61
What is the function of the liver?
To create bile | To clean and filter the blood
62
What does the exocrine pancreas produce?
Pancreatic juice in the duct cells Pancreatic enzymes in the acinar cells: Lipase, amylase, proteases (Trypsinogen, chymotrypsinogen and procarboxypeptidase A and B)
63
What does the endocrine pancreas produce?
Islets of langerhans. Alpha cells produce glucagon Beta cells produce insulin Delta cells produce somatostatin
64
Explai how a tissue is prepared to observe under the microscope?
1) Tissue is fixed to preserve it in a life like state, usually in a chemical that cross links protein such as formalin is used- stops decay 2) Tissue is thinly sliced to allow light to penetrate (1-15 microns) 3) Impregnate tissue with a support material like wax (thi is not necessary for blood cells or cell smears) 4) Tissue is dehydrated, put into oorganic solvent and placed into hot wax until it has fully penetrated 5) Thin sections are cut on a microtone and put onto slides, the wax is washed out and the tissue rehydrated.
65
What is a common stain in histology?
H&E Haematoxylin is a basic dye with affinity for acid molocules and stains then purple/blue eg nucleus/ribosomes Eosin is an acidic dye with an affinity for basic molecules and stains them pink/red. Most proteins are basic
66
Nervous tissue: What are the 3 main types of neurone?
Multipolar- many dendrites and one axon (most common Bipolar- one dendrite and one axon Pseudo unipolar- Short processes and axon in both directions
67
Nervous tissue: What is the ratio of neurones to glia?
1 neurone:10 glia
68
Nervous tissue: This is surrounded by a connective tissue coat. What is this called in the CNS and PNS?
``` CNS = meninges PNS = epineurum ```
69
Nervous tissue: What are the 3 types of glia and their functions?
Asterocytes - support ion transport and induce the blood brain barrier Oligodendrocytes - produce myelin in the brain and spinal cord Microglia - Provide immune surveillance
70
Bone: What cells make up bone?
Osteocytes
71
What are the 2 types of bone in a long bone?
Cortical bone- dense outer shell that makes up the shaft- diaphysis Cancellous/trabecular bone- occupies the epiphysis of the bone
72
What are the small canals called in bone which allow blood and nerves to enter the bone?
Haversian canals
73
Connective tissue: What makes up connective tissue?
Extracellular matrix and cells
74
Connective tissue: What is the extracellular matrix?
molecules secreted by the cells that provide structural and biochemical support to surrounding cells
75
What makes up the extracellular matrix?
Fibres: collagen, reticular and elastic fibres Ground substance: amorphous, space occupying material made of glycosaminoglygans (unbranched polysaccharide molecules) bound to proteins (forming glycoproteins) Tissue fluid
76
What are the cells found in connective tissue and what is ther function?
Fibroblasts: widely distributed that produce and maintain the extracellular matrix Adipose cells: fat cells found in connective tissue Osteocytes- bone cells Chondrocytes- cells of cartilage
77
What are the 2 types of soft connective tissue?
Loose: loosely packed fibres separated by abundant ground substance. plentiful cells Dense: Densely packed bundles of collagen fibres. -dense regular if the cells are aligned- tendon -dense irregular if fibre bundles run in many directions- dermis of skin
78
What is hard connective tissue?
Cartilage
79
What are the characteristics of cartilage?
Strong flexible compressable semi ridgid tissue Semi ridgid as ground substance is highly hydrated Avascular- receives nutrients from adjacent tissues by diffusion through the matrix
80
What are the 3 types of cartilage defined by the extracellular matrix?
Hyaline, aleastic and fibro cartilage
81
What makes up hyaline cartilage and where is it found?
Chondrocytes and cartilage matrix | Found at articular surfaces/ tracheal rings/ coastal cartilage and epiphyseal growth plates
82
What is the function of epithilium?
Covers the surface of the body lines hollow organs forms glands
83
Wht are the features of epithilial cells?
All attached to the basal lamina- a layer of extracellular components All nonvascular and obtain nutrients from capillaries in underlying tissue which diffuse across the basal lamina Polarised cells with a basal and apical surface
84
What are the functions of epithilia?
``` mechanical barrier- skin chemical barrier- stomch Absorption- intestine secretion- glands containment - bladder locomotion- cillia ```
85
What are the types of covering epithilial cells?
Simple, stratified or pseudostratified | Squamous, cuboidal or columnar
86
What are the two types of glandular epithilium?
Endocrine: products secreted towards the basal lamina and diffuse into capillaries for distribution- ductless glands (pituitary gland) Exocrine: products secreted towards the apical end of the cell into the lumen, duct or body surface. Duncted glands (salivary gland)
87
What are the 3 types of muscle?
Skeletal, smooth and cardiac muscle
88
What causes striations in skeletal muscle?
Arrangement of actin and myosin
89
What are the characteristics of smooth muscle?
Involuntary, visceral No striations Individual fibres are elongated spindle shaped cells Cigar shaped nucleus in the centre of each fibre
90
What are the characteristics of skeletal muscle?
Striated, voluntary Giant multiucleated cylindrical cells- long Many elongated nuclei at the periphery of the cell within the sarcolemma
91
What are the characteristics of cardiac muscle?
Striated but less prominent Fibres are shorter than skeletal muscle and branch to form complex networks Single nucleus at the centre of each fibre Contain intercollated discs
92
What is an intercollated disc?
FOund in cardiac muscle and pass across the fibres at irregular intervals- end to end attachment between cells with multiple intercellular junctions for mechanical integrity
93
Where is cardiac muscle found?
Walls of the heart and origin of great vessels
94
What are the 3 layers of blood vessels?
Tunica intima- singel layer of squamous epithilial cells (endothilium) supported by a basal lamina Tunica media- Some connective tissue but mostly mooth muscle orientated circumfrentially Tunica adventicia- made of supporting connective tissue and blend with connective tissue around it
95
Blood vessels contain 2 elastic membranes- what are these?
internal elastic membrane- separates tunica intima from tunica media External elastic membrane which sepates the media from the adventicia
96
What is an elastic artery?
Some of the smooth muscle in the tunica media is replaced with elastic tissue which provides elastic reciol to maintain BP
97
How do large arteries gain a blood supply?
Vaso vasorum- they cannot obtain nutrients from the lumen of vessels
98
Characteristics of arterioles?
1-2 layers of smooth muscle in the media and no adveticia. | Control blood flow to the tissues
99
WHat are the 3 tyes of capillaries and where are they found?
Continuous- no pores found in muscle, nerve, lung and skin Fenestrated- small pores ~50 nm found in the gut mucosa, endocrine glands and kidney Discontinuous/sinusoidal- larger gaps found in the liver, spleen and bone marrow
100
What is the function of capillaries?
Smallest blood vessels responsible for microcirculation
101
What is the function of post capillary venuoles?
Endothilial cells lined with a thin layer of connective tissue. Site for exchange allowing WBCs to to enter the tissues
102
When does a post capillary venuole become a venuole?
WHen some smooth muscle cells are found in the tunica media
103
What are the characteristics of veins?
Tunica intima, thin tunica media but no obvios tunica adventicia except large veins like SVC and IVC. Valves- folds in the tunica intima to prevent back flow
104
Which veins have longitudinal bundles of smooth muscle?
Large veins
105
What characterises lymph vessels?
Thin walled- look like capillaries but much larger | Valves
106
What is the function of lymph vessels?
Transport lymph to lymph nodes fro immune survaelence
107
Lymphatics have no central pump- what causes flow?
Hydrostatic pressure Compression of vessels due to skeletal muscle contraction Smooth muscle Valves
108
What percentage of blood is cells?
45% Erythrocytes, leukocytes and platelets
109
Which cells are granulocytes?
Neutrophils, basophils and eosinophils
110
Which cells are agranulocytes?
Lymphocytes and monocytes
111
How is blood separated?
Centrifugation 1) The erythrocytes are densest and after spinning form a pelet 2) The leucocytes are next with platelets and are found above the buffy coat 3) Plasma is the liquid portion at the top-supernatent
112
What is the difference between plasma and serum?
Serum has had the clotting factors removed by allowing the blood to clot and removing the clot before spinning the blood
113
What are the characteristics of erythrocytes?
Biconcave shape, 7 microns diamer, 1/3 of the volume is haemoglobin Network of flexible cytoskeleton elements allowing them to deform mature cells do not have a nucleus or organelles (immature cells in the bone marrow do have these)
114
What is the life span of a RBC?
120 days- old cells are removed by spleen and liver
115
What are the characteristics of neutrophils?
Granulocytes but these stain poorly with acid and basic dyes Multilobed nucleus Short lived- bone marrow produces lots 40-75% of leukocytes
116
What are the characteristics of eosinophils?
5% of leukocytes Granulocytes- basic granules with an affinity for acidic dyes- stain pink/red. Contain hydrolytic enzymes Bilobed nucleus Important in allergic reaction and parasitic/worm infections
117
What are the characteristics of basophils?
Granulocytes- acidic granules with an affinity for basic dyes- stain purple/blue. Contain histamine, heparin and other proinflamatory mediators- respond to allergens Bilobed nucleus High affinity for IgE receptors
118
What are the characteristics of monocytes?
Precursor to macrophages Largest blood cells Kidney bean shaped nucleus Tissue resident
119
WHat are the characteristics of lymphocytes?
No visible granules, little cytoplasm and a round nucleus | T and B cells cannot be distinguished down a mcroscope
120
What are the characteristics of platelets?
Small cell fragments- 2microns diameter Some have organelles but no nucleus Involved in hemostasis (prevention of blood loss) Have granules with coagulation factors
121
What is thrombocytosemia?
Low platelets
122
Where is the earliest site for erythrocyte formation?
Yolk sac at 3 weeks. In the second trimester the liver is the main site for hemopoiesis
123
Where are hemopoietic stem cells found in a foetus?
Liver and spleen
124
Where does hemopoiesis occur at birth?
All the bones
125
At maturity, where does hemopoiesis take place?
Vertebrae, ribs, skull, pelvis, proximal femurs. Marrow in other bones is mainly adipose tissue but in an emergency can begin blood cell formation Red marrow = blood Yellow marrow = Fat
126
Which cells produce platelets?
Megakaryocytes- found in the bone marrow Characterised by a very large nucleus as it undergoes duplication of nuclear material but not cell division Platelets form as extensions at the outer margins of the cell which fragment from the cell

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