Histology Flashcards
(99 cards)
1
Q
Composition of a cell
A
Water, lipids, proteins, carbohydrates and inorganic material
2
Q
Common features of eukaryotic cells
A
Membrane, cytosol, cytoskeleton, organelles, inclusions
3
Q
What is the cytosol?
A
A solution of proteins, electrolytes and carbohydrates which has fluid and gel-like properties
4
Q
What is the plasmalemma?
A
The bimolecular layer of amphipathic phospholipid molecules which surrounds a cell
5
Q
Examples of integral proteins
A
Receptors, channels, transporters, enzymes and cell attachment proteins
6
Q
What can be found in the plasmalemma?
A
Integral proteins, peripheral proteins and cholesterol
7
Q
What is the function of the nucleus?
A
Contains chromosomes and is the location of RNA synthesis
8
Q
Where is mRNA transcribed?
A
Nucleus
9
Q
Where is tRNA transcribed?
A
Nucleus
10
Q
Where is rRNA transcribed?
A
Nucleolus
11
Q
What is euchromatin?
A
Dispersed chromosome material actively undergoing transcription
12
Q
What is heterochromatin?
A
Condensed chromosome material not actively undergoing transcription
13
Q
What is the Golgi apparatus?
A
A group of flattened membrane-bound cistern arranged in sub-compartments
14
Q
What are the functions of the Golgi apparatus? (3)
A
- Adds sugars
- Cleaves some proteins
- Sorts macromolecules into vesicles
15
Q
Describe the nuclear membrane
A
Has an inner and outer membrane with nuclear pores and a perinuclear cistern in between
16
Q
Describe the mitochondrial membrane
A
Has an inner and outer membrane, inner membrane (Cristae) gives large internal surface area due to extensive folding
17
Q
What are the functions of the mitochondria?
A
Generation of ATP and synthesis of certain lipids and proteins
18
Q
Types of cellular transport
A
- Diffusion
- Transport proteins
- Vesicular transport
19
Q
Describe endocytosis
A
Cell membrane invaginate, fuses endocytotic vesicle buds into the cell, receptor mediated
20
Q
Describe phagocytosis
A
(for bacteria/larger particulate material) bacteria binds to cell surface receptors triggering extensions of the cell to engulf it forming a phagosome, which binds to lysosome = phagolysosome
21
Q
What is the average size of a red blood cell?
A
6 microns
22
Q
What are inclusions?
A
Something synthesised by the cell itself or taken up from the extracellular environment in an endocytotic vessel, dispensable and may be present only in transients
23
Q
Describe microfilaments
A
Composed of actin, can assemble into filaments and later dissociate making them very dynamic, usually accumulate under the cell membrane
24
Q
Describe intermediate filaments
A
Composed of six main proteins which vary depending on cell type and are used in pathology to determine tumour origin, more than 50 types of the main proteins, bind intracellular elements together and to the plasmalemma
25
Describe microtubules
Hollow tubules composed of alternating alpha and beta tubular subunits, can be assembled and disassembled, originate from MTOC or centrosome, include stabilising proteins, motorway network of the cell, dynein and kinesin are ATPases that move along them, important in cell division and movement
26
Place microtubules, microfilaments and intermediate filaments in descending order of size.
- Microtubules, 25nm
- Intermediate filaments, 10nm
- Microfilaments, 7nm
27
What is contained within the MTOC?
A pair of centrioles composed mainly of specialised microtubule segments
28
Describe ribosomes
Formed in nucleolus, important in protein synthesis, small subunit (binds to RNA) and large subunit (catalyses the formation of peptide bonds), export depends on nuclear pore complex
29
What is the endoplasmic reticulum?
A net-like structure which forms an interconnected network of flattened membrane-bound compartments and is continuous with the nuclear membrane
30
Describe the RER
Studded with ribosomes, plays a vital role in synthesis of proteins, abundant in cells with high metabolic activity, initiates glycoprotein formation
31
Describe the SER
Continues processing of proteins produced in the RER, sire of the synthesis of lipids, little amount of SER in most cells
32
What are intercellular junctions?
Mechanisms that link cells together into a functional unit
33
What is a junctional complex?
Close association of several types of intercellular junctions
34
What are the three types of intercellular junctions?
- Occluding junctions (zonula occludens/tight junctions)
- Anchoring junctions
- Communicating junctions (gap junctions)
35
What role do occluding junctions play?
Form seals by linking cells together to prevent diffusion
36
What role do anchoring junctions play?
Provide mechanical strength and stability
37
Describe the two types of anchoring junctions
1) Adherent junctions/zonula adherent, link submemnrane actin bundles of adjacent cells
2) Desmosomes/macula adherens, link submemnrane intermediate filaments of adjacent cells, are stronger, form anchoring spots
38
What role do communicating junctions play?
Allow selective diffusion of molecules between adjacent cells using a circular patch studded with several hundred pores produced by connexons
39
Where are communicating junctions found?
- Epithelia (coverings of body surfaces)
- Some smooth muscle (e.g. intestines)
- Cardiac muscle (where spread of excitation is critical)
40
Describe the steps in preparing specimens for light and electron microscopy
1) Tissue is fixed to stop it from degrading/to preserve it in its current state using a chemical e.g. formalin which crosslinks proteins/enzymes
2) The tissue is impregnated with a support e.g. wax, by first dehydrating it (passing it through ethanol then an organic solvent which is miscible and so allows impregnation by wax)
3) Thin sections of tissue are cut on the microtome and put on microscope slides
4) Wax is then washed out
5) The tissue is rehydrated
6) Stains are used that deferentially bind to particular types of molecules
41
What are artefacts?
When there is distortion or changes from the original tissue during histological techniques (e.g. shrinkage)
42
What is the problem with histological techniques?
A simple bent tube can produce lots of different shapes when sliced thinly as we are attempting to see a 3D object in 2D
43
Describe the most commonly used stains
H&E - haematoxyline (purple, basic, acidic affinity e.g. binds to nucleus) and eosin (pink, acidic, basic affinity e.g. binds to most proteins in the cytoplasm)
44
What are the four basic tissue types?
- Epithelium
- Connective tissue
- Muscle
- Nervous tissue
45
What is the role of connective tissue?
Forms the framework of the body and has a dynamic role in development, growth, homeostasis and energy storage
46
What are the three types of connective tissue?
- Soft connective tissue e.g. tendons and ligaments
- Hard connective tissue
- Blood and lymph (controversial)
47
Describe the components of connective tissue
- Cells (fibroblasts, adipose cells, osteocytes, chondrocytes)
- Extracellular matrix, which far predominates the cells (fibres, ground substance, tissue fluid)
48
What are the three types of soft connective tissue?
- Loose connective tissue
- Dense regular connective tissue
- Dense irregular connective tissue
49
What is loose connective tissue?
Loosely packed fibres separated by ground substance, lots of cells
50
What is dense regular connective tissue?
Packed bundles of aligned fibres (e.g. tendons)
51
What is dense irregular connective tissue?
Packed bundles of fibres running in many directions (e.g. the dermis of the skin)
52
What are the two types of hard connective tissue?
- Cartilage
| - Bone
53
Describe the histology of cartilage
Strong, flexible, compressible, semi-rigid tissue, highly hydrated with ground substance, avascular, receives nutrients by diffusion through matrix
54
What are the three types of cartilage?
- Hyaline (tracheal rings + costal cartilage)
- Elastic
- Fibrocartilage
55
Describe the histology of bone
Living tissue, penetrated by small canals for blood vessels and nerves, contains living cells called osteocytes, undergoes remodelling throughout life
56
What are the two types of bone?
- Diaphysis = dense cortical bone
| - Epiphyses = fine meshwork of cancellous or trabecular bone
57
What is muscle tissue?
Tissue that is specialised to generate force by contracting
58
What are the three types of muscle tissue?
- Smooth muscle
- Skeletal muscle
- Cardiac muscle
59
Describe smooth muscle
Involuntary/visceral muscle, no visible striations, elongated spindle-shaped cells, nucleus near centre of each fibre
60
Describe skeletal muscle
Voluntary/striated muscle, responds to conscious control, giant, multinucleate, long cylinders, many elongated nuclei at cell periphery sarcolemma
61
Describe cardiac muscle
Forms the major part of the walls of the heart chambers and origins of great vessels, less prominent striations, normal sized cells, bolted together in a complex network, single nucleus
62
What are intercalated discs?
The bolting together of two cardiac muscle cells through multiple intercellular junctions
63
What is the function of nervous tissue?
Serves a control function for rapid communication between different parts of the body
64
What are the components of nervous tissue?
- Neurons
| - Glia (supporting cells which outnumber neurons in the CNS)
65
What surrounds nervous tissue?
A connective tissue coat called:
- The meninges in CNS
- The epineurium in PNS
66
Describe the three types of neurons
- Multipolar: many dendrites and one axon
- Bipolar: one dendrite and one axon
- Psuedounipolar: short dendrites give rise to an axon in two directions
67
Describe the principle glia cells found in the CNS
- Astrocytes: support, ion transport, induce blood brain barrier
- Oligodendrocytes: produce myelin in the brain and spinal cord
- Microglia: produce immune surveillance
68
Describe the principle glia found in the PNS
- Schwann cells: produce myelin and support axons
69
What are the functions of the epithelia?
- Mechanical barrier (skin)
- Chemical barrier (stomach lining)
- Absorption (small intestine lining)
- Secretion (salivary gland)
- Containment (lining of urinary bladder)
- Locomotion (by cilia)
- Minor, sensation and contractility
70
What is the role of the epithelial tissue?
Covers the surfaces of the body, lines hollow organs and forms many glands and some solid organs (liver)
71
How do epithelial cells fit together?
Minimum intercellular space, non-vascular, nutrients diffuse across basal lamina, usually polarised, apical and basal ends of the cells differ
72
What are the different shapes of epithelial cells?
- Squamous cells (flattened like a fish scale)
- Cuboidal cells
- Columnar cells
73
What are the names for the different number of epithelial cell layers?
- Simple = one layer
- Stratified = two or more layers
- Pseudostratified
74
What is pseudostratified epithelia?
Where the epithelial tissue appears to have multiple layers but in fact all cells are in contact with the basal lamina
75
What are epithelial cell surface specialisations?
- Microvilli (brush border)
- Cilia (microtubules)
- Presence of layers of keratin proteins on the tissue surface (keratinised)
76
What are goblet cells?
Specialised epithelial cells which are single cell mucous glands
77
What is the role of glandular epithelia?
Produce secretory products e.g. sweat, milk, oil, enzymes, hormones, mucous
78
What are endocrine (ductless) glands?
Glands in which the product is secreted towards the basal lamina and distributed by the vascular system
79
What are exocrine (ducted) glands?
Glands in which the product is secreted into a duct or onto the body surface
80
What are the three major salivary glands?
- parotid gland
- submandibular gland
- sublingual gland
81
What is the role of the salivary glands?
To modify the saliva passing through them by removing salt
82
What are the four layers of the digestive tract?
1) Mucosa
2) Submucosa
3) Muscularis externa/propria
4) Serosa/adventitia
83
What are the three layers of the mucosa?
1) Epithelium
2) Lamina propria
3) Muscularis mucosae
84
What are the two layers of the muscular external/propria?
- Inner circular layer
| - Outer longitudinal layer
85
What is the enteric nervous system?
Nervous system for the digestive tract which receives input from the ANS, but is capable of coordinating gut motility locally
86
Describe the anatomy of the enteric nervous system
Has neurons in groups called ganglia between two muscle layers in the muscular externa
87
What are bronchi?
Large diameter airways with hyaline cartilage
88
What are bronchioles?
Smaller airways with no cartilage and smooth muscle predominating their wall
89
What is the pancreas?
Both an endocrine and an exocrine gland which produces digestive juices and some hormones
90
What digestive enzymes does the pancreas make?
Proteases, lipase and nucleases (inactive, activated in the duodenum)
91
What are the islets of Langerhans?
Small scattered islands of tissue in the endocrine pancreas which produce a number of hormones including insulin
92
Describe the trachea
An airway, lined with respiratory epithelium, has a thin lamina propria, contains hyaline cartilage of the tracheal rings
93
Describe the anatomy of the liver
Made up of a large number of lobules in a hexagonal arrangement, with a branch of the hepatic portal vein at each corner. Blood is delivered to the lobule by the hepatic arteries. In the centre is a central vein (CV) which drains to the hepatic vein. Blood passing from corner to centre via hepatic sinusoids (spaces for blood flow) passes sheets of liver cells called hepatocytes.
94
What are the components of the hepatic triad?
- Branch of the hepatic portal vein
- Bile duct
- Hepatic arteriole
95
Describe the histology of blood vessels
Lumen, tunica intima, interanal elastic membrane, tunica media, external elastic membrane, tunica adventitia
96
What are the three types of capillaries?
1) continuous
2) fenestrated
3) discontinuous/sinusoidal
97
What are the two components of blood?
1) plasma (55%)
| 2) formed elements (45%)
98
What is plasma made up of?
Water (90%), proteins, nutrients, salts
99
What are the components of the formed elements of blood?
- red cells/erythrocytes
- white cells/leukocytes
- platelets
