Histology Flashcards
1
Q
Why do you study microscopic anatomy?
A
to allow you to assess and understand pathological changes that affect your patient
2
Q
which cells contains the most water?
A
embryonic cells
3
Q
what are features that are common in all eukaryotic cells?
A
an outer membrane, an inner cytosol, a cytoskeleton, membrane bound organelles in the cytosol, inclusion
4
Q
what is an inner cytosol in a cell?
A
a solution of proteins, electrolytes & carbohydrates. both fluid and gel like properties.
5
Q
what is a cytoskeleton of a cell?
A
determines the shape and fluidity of the cell, made from thin and intermediate filaments and microtubules
6
Q
what are inclusion?
A
structures in the cytoplasm, that can be bound to the membrane. they have been synthesised by the cell itself or taken up from the extracellular environment. they are dispensable
7
Q
what is the plasmalemma?
A
separates the cytoplasm from the outside environment. bimolecular layer of amphipathic phospholipid molecules with their hydrophilic heads at the outer and inner surfaces and their hydrophobic fatty acid chains facing towards the middle of the two layers
8
Q
where do the integral proteins insert themselves into?
A
the cell membrane within the plasmalemma
9
Q
what are examples of integral proteins?
A
receptors, channels, transporters, enzymes and cell attachment proteins.
10
Q
what is exocytose?
A
cellular secretion
11
Q
what is endocytose?
A
when substances are brought into the cell
12
Q
what does is mean by the membrane is fluid?
A
can change shape easily, membrane proteins can diffuse laterally, but many are anchored, therefore many proteins are not distributed equally in the membrane
13
Q
what does is mean when a membrane is selectively permeable?
A
highly permeable to: water, oxygen, small hydrophobic molecules. virtually impermeable to charged ions
14
Q
what provides a selective structural barrier to the cell?
A
the plasmalemma
15
Q
what does the phospholipid bilayer contain?
A
integral and peripheral proteins and cholesterol imbedded
16
Q
what are organelles?
A
small intracellular organs with a specific function and structural organisation
17
Q
what are the functions of the cell maintained by?
A
set of filamentous cytosolic proteins, the cytoskeletal proteins
18
Q
what are the three classes of filaments?
A
microfilament - composed of the protein actin
intermediate filaments - composed of 6 main proteins, which vary in different cell types
microtubules - composed of 2 tubulin proteins
19
Q
how do filament proteins become attached to the cell membrane and each other?
A
by anchoring and joining proteins to form a dynamic 3D internal scaffolding in the cell. they form a network throughout the cytoplasm
20
Q
what are microfilaments (MF)?
A
globular actin polymerises to form filamentous actin, actin molecules can assemble into filaments and then dissociate, making them dynamic cytoskeletal elements. often accumulate under the cell membrane
21
Q
what are intermediate filaments?
A
they bind intracellular elements together and to the plasmalemma. so many types that are then divided up into classes which are then used in pathology to identify tumour origins
22
Q
what are microtubules?
A
hollow tubule composed of two types of tubulin subunits, alpha and beta in an alternating array. they can be assembles and disassembled. originate from centrosome. include stabilising proteins.
23
Q
what are stabilising proteins?
A
microtubule associated proteins (MAPs), important in cilia, flagella and the mitotic spindle
24
Q
what serves as the motorway network of the cell?
A
microtubules - two proteins, dyne and kinesis attach to the microtubules and move along them. they associate with the membranes of the organelles and vesicles and drag them along the microtubule.
25
what is kinase?
an ATPase that moves toward the cell periphery
26
what is dynein?
an ATPase that moves toward the cell centre
27
what is the nucleus enclosed by?
the nuclear envelope
28
what is the nuclear envelope composed of?
an inner and outer nuclear membrane with pores providing continuity with the cytoplasm.
29
what is the perinuclear cistern?
found between the two sheets of the nuclear envelope and is continuous with the cytoplasmic RER
30
what is the nucleus?
the location of RNA synthesis
31
where are mRNA and tRNA transcribed?
in the nucleolus, a dense area within the nucleus
32
what does the nucleus contain?
chromosomes, Euchromatin (DNA that's dispersed and actively undergoing transcription), heterochromatin (DNA that's highly condensed and not undergoing transcription)
33
True or false, the nucleus is surrounding by a single nuclear membrane?
False - a double nuclear membrane
34
where are ribosomes formed?
the nucleus
35
what does the export of ribosomes depend on?
the nuclear pore complex
36
what do the subunits of a ribosome do?
small subunit binds RNA and large subunit catalyses the formation of peptide bonds
37
what does the endoplasmic reticulum form?
a network of interconnecting membrane-bound compartments in the cell
38
what is the RER studded with?
ribosomes
39
what is the amount of ER in a cell dependent on?
how active a cell is
40
where do proteins that are unpackaged in the cytosol get synthesised?
on polysomes, floating free in the cytosol
41
what is RER associated with?
protein synthesis and initiation of glycoprotein formation
42
what does SER do?
continue the processing of proteins produced in the RER, plays a vital role as the site of synthesis lipids.
43
what is the Golgi apparatus/complex?
composed of a group of flattened, membrane bound cisternae, arranged in sub-compartments
44
what are the sub-compartments of the Golgi apparatus?
transport vesicles that arrive in the Golgi from the RER/SER, Golgi cisterns function in the modification and packaging of macramolecules that were synthesised in the ER, e.g adds sugar, cleaves some proteins, sorts macramolecules into vesicles
45
what are macramolecules?
many monomers linking together, forming a polymer, e.g. lipids
46
what are mitochondria?
the power generators of the cell, function in the generation of ATP, via oxidative phosphorylation and the synthesis of certain lipids and proteins
47
what is the shape of mitochondria?
oblong and cylindrical
48
what are mitochondria composed of?
an outer and inner membrane. the inner membrane is extensively folded to form cristae, which act to increase the available surface area
49
True or false mitochondria contain their own DNA and system for protein production?
true
50
what are intercellular junctions?
specialised membrane structures which link individual cells together into a functional unit. particularly in epithelia
51
what are the three types of intercellular junctions?
occluding junctions - link cells to form a diffusion barrier
anchoring junctions - provide mechanical strength
communicating junctions - allow movement of molecules between cells
52
what does an occluding junction do?
prevent diffusion, links cells to form a diffusion barrier, , appear as a focal region of close apposition between adjacent cell membranes
53
what are occluding junctions also known as?
tight junctions or zonula occludens
54
what do anchoring junctions do?
link submembrane actin bundles or adjacent cells, transmembrane cadherin molecules bind to each other in the extracellular space and through link molecules, to actin of the cytoskeleton. desmosomes: link submenbrane intermediate filaments of adjacent cells. also called macula adherent. desmosomes are very common in the skin providing mechanical stability
55
what are anchoring junctions also known as?
adherent junctions or zonula adherent
56
what do communicating junctions do?
allow selective diffusion of molecules between adjacent cells, each junction is a circular patch studded with several hundred pores. pores are produced by connexon proteins. found in epithelia but also in smooth muscle and in cardiac muscle, where it is critical for the spread of excitation
57
what are communicating junctions also known as?
gap junctions
58
what is a junctional complex?
close association of several types of junctions found in certain epithelial tissues.
ZO: zonual occulens
ZA: zonula adherens
MA: macula adherens
59
how is material transported via diffusion?
via transport proteins (pumps or channels) by incorporation into vesicles (vesicular transport)
60
what are two types of vesicular transport?
endocytosis and phagocytosis
61
what is endocytosis?
material from extracellular space can be incorporated into the cell by endophytes. the cell membrane invaginates, fuses and the newly made endocytotic vesicle (endosome) buds into the cell. this process is often receptor mediated. exocytosis works in a reverse fashion, to discharge
62
what is phagocytosis?
bacteria or larger particulate material from the extracellular space can be incorporated into the cell by phagocytosis. the bacterium binds to the cell surface receptors triggering extensions of the cell to engulf it forming a phagosome. the phagosome binds with a lysosome carrying digestive enzymes producing a phagolysosomes
63
why is tissue fixed?
to preserve it in a life-like as state as possible
64
how does a tissue have to be sliced to allow light to penetrate the tissue?
thinly
65
what support material is commonly used to impregnate issue with when analysing it?
wax
66
how is the tissue penetrated by the support material in order for it to be analysed?
dehydrated, put into organic solvent and placed into hot wax until the tissue is fully penetrated. thin sections are then cut by a microtome, the wax is washed off and the tissue is rehydrated.
67
what are artefacts in tissues in the context of being analysed?
distortions made from the process of preparing the tissue before analysis, e.g. shrinkage
68
how do stains work?
different stains bind to particular types of molecules, allowing molecules to be differentiated from each other and identified
69
what does H&E stand for
haematoxylin (basic dye with an affinity for acidic molecules) and eosin (acidic dye with an affinity for basic molecules)
70
what are the 4 basic tissue types?
epithelium, connective tissue, muscle and nervous tissue
71
what is epithelia?
cover surfaces of the body or line hollow organs and also form many glands. they occur as sheets of cells and vary widely in size, shape, orientation and function
72
what is connective tissue?
forms the framework of the body, but beyond that it has a dynamic role in the development, growth and homeostasis of tissues and, via fat, in energy storage
73
what are muscle cells?
specialised to generate force by contracting. there are three major kinds in the body: smooth, skeletal and cardiac
74
what is nervous tissue?
consists of neutrons and their supporting cells. nervous tissue serves a control function and allows for rapid communication between different body parts
75
what are the common features of epithelia?
adhesion between epithelial cells is strong, forming sheets of cells, with minimum intercellular space.
have a basal surface, layer of extracellular matrix components called basal lamina to which cells are attached
all non-vascular, gaining nutrients from capillaries in underlying tissue, that must diffuse across basal lamina
polarised, giving the apical and basal ends of the cell
form solid organs and glands
76
what are some functions of epithelia?
```
mechanical barrier (skin)
chemical barrier (lining of the stomach)
absorption (lining of the intestine)
secretion (salivary glands)
containment (lining of urinary bladder)
locomotion (by cilia)
minor functions: sensation, contractility
```
77
how are the number of epithelial layers described?
```
simple = 1
stratified = 2
pseudostratified = appears to have multiple layers but all cells are in contact with the basal lamina
```
78
what is the basal lamina of a cell?
layer of the extracellular matrix secreted by epithelial cells which the epithelium sits
79
what does an adhesion mean?
a band of scar tissue that binds two parts of your tissue that are not normally joined together
80
how are the shapes of cells described?
squamous = flattened
cuboidal
columnar
81
what does it mean if a cell is keratinised?
presence of layer of keratin proteins on the tissue surface.
82
what does the term brush border mean?
when the cell surface is covered in microvilli
83
what is glandular epithelia?
produce secretory products e.g. mucous and sweat
84
what do endocrine glands do?
products secreted towards the basal end of the cell (end sitting on the basal lamina) then distributed by the vascular system throughout the body. termed ductless gland as they have lots of capillaries to take product away instead of a duct.
85
what do exocrine glands do?
product secreted toward apical end of the cell either into lumen of an internal space, into a duct, or onto the body surface. termed ducted gland
86
what are the three types of connective tissue?
soft connective tissue, hard connective tissue, blood and lymph
87
what are examples of soft connective tissue?
tendons, ligaments, mesentery, storm of organs, dermis of skin
88
what are examples of hard connective tissue?
bones and cartilage
89
what does connective tissue consist of?
extracellular matrix, cells, type of connective tissue is determined by the relative amounts of these components
90
where do lots of cells in soft connective tissue migrate from?
the blood stream
91
what are the types of dense soft connective tissue?
dense regular = fibres are aligned e.g. tendon
| dense irregular = fibre bundles run in many different directions e.g. dermis of the skin
92
What is cartilage?
hard connective tissue
strong, flexible, compressible, semi-rigid tissue (due to the highly hydrated ground substance - GAGS and proteoglycans)
avascular and receives nutrients from adjacent tissues by diffusion through its matrix
93
what are the three types of cartilage and what are they defined by
hyaline, elastic and fibrocartilage. defined by the extracellular matrix
94
most common sites hyaline cartilage is found?
articular surfaces, tracheal rings, costal cartilage, epiphyseal growth plates
95
what is a chondrocyte?
mature cartilage cell
96
what is bone?
hard connective tissue
an outer shell of dense cortical bone makes up the shaft (diaphysis)
undergoes remodelling throughout life
living tissue
penetrated by small canals (Haversian canals) for blood vessels and nerves
97
what are osteocytes?
the living cells in bones
98
what is cancellous bone?
fine meshwork of bone, that occupies the ends of the bone (the epiphyses)
99
what is the cytoplasm of a muscle cell packed with?
contractile fibres, meaning these cells are highly specialised for the production of contractile force
100
how is force by the muscles produced?
the movement of actin fibres over myosin fibres, with the aid of a number of accessory proteins
101
what are the major types of muscle tissues?
smooth, skeletal and cardiac
102
what is smooth muscle?
```
structurally the simplest
involuntary/visceral
no visible striations
not under conscious control
predominantly found in organs
```
103
what is skeletal muscle?
voluntary/striated
| muscles of the body that respond to conscious control
104
what is the typical skeletal muscle fibre like?
giant multinucleate cyndrical cell.
attain considerable lengths
many nuclei that are elongated and located at the periphery of the cell, just internal to the cell membrane (in muscle cells sarcolemma)
105
what is cardiac muscle?
forms major parts of the walls of the heart chambers and origins of the great vessels
less prominent striations
short fibres that branch to form a complex network
muscle cells have single nucleus near centre of the fibre
intercalated discs pass across the fibres at irregular intervals, sites of end-to-end attachments between adjacent cells containing intercellular junctions to maintain mechanical integrity
106
what is nervous tissue?
consists of neurons and support cells (glia)
glia outnumber neutrons by about 10:1 in the central nervous system
surrounded by connective tissue 'coat'
- meninges for CNS
- epineurium for PNS (peripheral nervous system)
107
what are Schwann cells?
produce myelin and support axons, form of PNS glia
108
what are the forms of glia? (CNS)
astrocytes: support ion transport, induce blood brain barrier
oligodendrocytes: produce myelin in the brain and spinal cord
microglia: provide immune surveillance
109
what is myelin?
an insulating layer
110
there are 3 major glands (salivary glands)?
parotid, submandibular, sublingual
111
what do serous and mucous secreting cells secrete?
a watery fluid and mucous
112
what are salivary glands?
epithelial, striated ducts, modify saliva passing through them by pumping salt out of the fluid so our saliva is hypotonic to blood
113
what are the 4 layers of the digestive tract starting from the lumen going out?
mucosa
submucosa
muscularis externa
serosa or adventitia
114
what are the 3 parts of mucosa?
epithelium: sits on a basal lamina
lamina propria: loose connective tissue
muscularis mucosae: thin layer of smooth muscle
115
what is the submucosa?
loose connective tissue
116
what is the muscularis externa?
2 thick layers of smooth muscle, an inner circular layer and an outer longitudinal layer
117
what is advantitia?
outer layer of connective tissue that either suspends the dogestive tract or attaches to other organs
118
what are the variations in mucosa?
protective, secretory, absorptive, protective and absorptive
119
what is the digestive systems nervous system called?
enteric nervous system
120
how does the enteric nervous system work?
receives input from the automatic nervous system, but is capable of coordinating gut motility locally. most of the neutrons live in groups called ganglia between the two muscle layers that make up the muscularis external
121
what makes up the tracheal rings?
hyaline cartilage
122
how are particles trapped in the trachea?
goblet cells of the epithelium and submucosal glands produce a viscous fluid that coats the surface of the airway, trapping particles that are then propelled out of the airway by the cilia
123
what are the differences between bronchi and bronchioles?
bronchi - larger diameter airways, hyalin cartilage in their wall
bronchioles - smaller airways, no cartilage, smooth muscle predominates in their wall
124
what are alveoli lined by?
simple squamous epithelium
125
what is the basic structure of the liver?
made up of a larger number of lobules
at each corner there is a branch of the hepatic portal vein and hepatic artery, each delivering blood to the lobule.
in the centre there is the centre vein which drains the hepatic vein.
blood passing from the corner to the centre via hepatic sinusoids passes sheets of liver cells called hepatocytes
126
what are sinusoids?
spaces for blood flow
127
what is the portal triad made up of?
branch of hepatic portal vein, bile duct and hepatic arteriole
128
what type of gland is the pancreas?
exocrine and endocrine gland
129
what is in digestive juices?
proteases to breakdown proteins, lipases to breakdown lipids and nucleases to breakdown DNA/RNA
130
how do digestive juices enter the duodenum?
via the pancreatic duct
131
what does the endocrine nucleus consist of?
small, scattered islands of tissue called islets of Langerhans, which produce hormones including insulin
132
what are the three basic layers of a blood vessel starting from the inside?
tunica intima, tunica media and tunica adventitia
133
what is the tunica intimacy made of?
endothelial cells supported by a basal lamina and a thin layer of connective tissue
134
what is the tunica media made of?
smooth muscle
135
what is tunica adventitia made up of?
supporting connective tissue
136
where would you find an elastic tissue called the internal elastic membrane?
between the tunica intima and media
137
where would you find an elastic tissue called the external elastic membrane?
between the tunica media and adventitia
138
what is the smooth muscle in the tunica media of the aorta replaced by?
sheets of elastic fibres (elastic arteries) providing elastic recoil
139
what is a blood vessels own vascular supply called?
the vasa vasorum
140
what are capillaries made up of?
endothelial cells and a basal lamina
141
what are the three types of capillary?
continuous: muscle, nerve, skin
fenestrated: have small pores, endocrine glands
discontinuous/sinusoidal: have large gaps, spleen, bone marrow
142
what type of network to capillaries form?
anastomitic network
143
where do capillaries drain into?
post capillary venules
144
what are post capillary venules composed of?
lined with endothelial cells and contain connective tissue
145
why to veins have valves?
to prevent back flow of blood
146
what does the lymph vascular system do?
drain excess tissue fluid (lymph) into the blood stream. transports lymph to lymph nodes for immunological surveillance
147
what are the three formed elements if blood?
red cells, white cells and platelets
148
what are the two categories of white blood cells?
granulocytes and agranulocytes
149
what are granulocytes?
neutrophils, eosinophils, basophils
150
what are granulocytes?
lymphocytes and monocytes
151
what's the name of a red blood cell?
erythrocyte
152
what type of blood cell has no nucleus?
a mature red blood cell
153
what's the most common type of leukocyte?
neutrophil
154
what is the nucleus of a neutrophil like?
multi-lobed nucleus
155
what is the nucleus of a eosinophil like?
bilobed nucleus
156
what is the nucleus of a basophil like?
bilobed nucleus often obscured by granules
157
what do basophils do?
act as effectors in allergic reactions
158
what do eosinophils do?
induce and maintain inflammation
159
what is a macrophage?
specialised cell involved in phagocytosis and destruction of bacteria and other pathogens
160
what is the nucleus of a monocyte like?
non-lobulated
161
what does a monocyte do?
serve as a precursor of tissue macrophages, forming the mononuclear phagocyte system
162
what's the nucleus of a lymphocyte like?
round
163
what are the two classes of lymphocyte?
T cells and B cells
164
what does a B cell do?
give rise to antibody secreting plasma cells
165
what do T cells do?
form a complex set of cells that perform many defence functions
166
what type of nucleus does a platelet have?
has no nucleus
167
do platelets have granules?
yes
168
what is the main site of blood formation?
bone marrow
169
what type of cells produce platelets?
megakaryocytic
170
what structures arise from the ectoderm?
brain, epidermis of skin, nails, hair, spinal cord
171
what structures arise from the mesoderm?
skeletal muscle, axial skeleton, kidney and ureter, gonads and associated structures, dermis, lining of the body walls, cardiovascular system, voluntary muscles
172
what structures arise from the endoderm?
lining of the gut wall lining of the respiratory tract, lining of the bladder and urethra
173
what is a synovial joint?
fluid filled space between the bones of the joint (the synovial cavity). this provides extra cushioning. more moveable than others.
174
what are ligaments?
hold together the cartilage on the end of bones
175
what is a fibrous joint?
tough joints held together by dense connective tissue. these are called sutures and are seen between the bones of the skull
176
what is a cartilaginous joint?
ones that are held together by cartilage, e.g. intervertebral joints, joint between the manubrium and the sternal body
