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CBA- 1 > Histology > Flashcards

Histology Flashcards

1
Q

what are tissues

A

aggregates or groups of cells organized to perform specific functions

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2
Q

what are the four basic tissues

A

epithelial
connective
muscular
nervous

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3
Q

what are the similarites between all tissue types

A

all contain cells

cells that make up tissues have similar functions

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4
Q

define epithelium

A

layer(s) of closely apposed cells with a minute amount of intercellular material resting on a basement membrane

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5
Q

general functions of covering epithelial tissues

A

cover/line body cavities, organs, surfaces, tubes

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6
Q

what the general characteristics and functions of covering epithelial tissues

A

as an interference surface (protection, absorbtion, filteration, secretion, excretion)
exhibits polarity (apical-superior and basal-inferior surfaces)
avascular but innervated
supported by connective tissue
ability to regenerate
cellular

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7
Q

two types of classification of covering epithelium

A

on the bases of layers

on the bases of type of cells

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8
Q

describe simple squamous epithelium

A

single layer of thin flattened cells

ovoid centrally placed nucleus

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9
Q

locations where simple squamous epithelium is present

A

endothelium (internal surfaces of heart, blood vessel, lymphatics)
mesothelium (lines the pericardial, pleural, peritoneal cavities
alveolar epithelium

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10
Q

describe simple cuboidal epithelium

A

single layer of cube shaped cells
spherical centrally placed nucleus
hexagonal or polygonal surface view

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11
Q

locations where simple cuboidal epithelium is present

A

distal tubules of nephron
surface epithelium of ovary
lining of certain ducts of glands

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12
Q

describe simple columnar epithelium

A

single layer of column shaped cells

basally located oval nucleus

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13
Q

describe a special property of simple columnar non- ciliated epithelium and its locations

A

may exhibit microvilli to increase SA

lines gall bladder, stomach, intestine

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14
Q

describe a special property of simple columnar ciliated epithelium and its locations

A 
contains cilia (crew cut appearance)- a dark band extending across the cell at the bas e of cilia due to presence of basal body
lines uterine tubes and uterus
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15
Q

describe pseudostratified columnar ciliated epithelium

A

single layer of cells resting on basement membrane
not all cells reach luminal surface
nuclei lie at different levels within the basal2/3 of the epithelium

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16
Q

location of pseudostratified columnar ciliated epithelium

A

eustachian tubes, nasal cavities, nasopharynx, paranasal sinuses

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17
Q

describe properties and functions of stratified squamous epithelium

A

main protective layer
number of layers is variable
polyhedral cells which gradually flatten towards the surface layers
shape o nucleus corresponds to shape of cells
no spaces between cells visible under L/M
they protect underlying tissues

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18
Q

special property and location stratified squamous keratinized epithelium

A

non nucleated
contain keratin protein
epidermis of skin
epithelial lining in parts of oral cavity

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19
Q

special property and location of stratified squamous non-keratinized epithelium

A

no keratin formation

lines parts of oral cavity, esophagus, oropharynx, lower part of anal canal, vagina

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20
Q

describe special property and location of stratified cuboidal epithelium

A

2-3 layers
basal layer low columnar
surface layer cuboidal
ducts of sweat glands

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21
Q

describe stratified columnar epithelium and its location

A

non ciliated

parts of ductus deferens and male urethra/ main ducts of salivary glands/ conjunctival epithelium

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22
Q

describe the properties of cilia

A

motile extension of cytoplasm covered by cell membrane
contain central pair of microtubules surrounded by central sheath with radial spokes extending from them
nine doublet comprising of A and B subunit surrounding the central sheath
dynein and nexin proteins connect the 9 doublets
A subunit is of 13 tubulin polymers while B subunit is of 10
5-10 micrometer in height 0.2 um in diameter

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23
Q

describe microvilli

A

fingerlike projections of cytoplasm covered in cell membrane seen n E/M
striated and brush like border
variable number of microvilli are present on each cell
actin core is anchored at the base by terminal web(myosin 2 and tropomyosin) and at the sides by fascin and fimbrin
apical portion is called apex villin
1-2um in height/ 0.1um in diameter

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24
Q

describe stereocilia

A 
long microvilli 30um 
villin is absent 
erzin replaces myosin 1
alpha actinin is present
thick stem is connected by cytoplasmic bridges
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25
Q

locations of stereocilia

A

epididymis of ear

taste buds

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26
Q

locations of microvilli

A

epithelial cells of small intestine

epithelial cells of proximal convoluted tubules of nephron

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27
Q

locations of cilia

A

respiratory epithelium

epithelial lining of uterine tubes and uterus

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28
Q

write a short note on flagellum

A

it is a long motile, whip like projection from a cell
only sperm cells have this
avg length is 55um
produces undulating movements that help in the locomotion of the whole cells

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29
Q

describe goblet cell

A 
unicellular gland 
mucous producing 
dilated upper part
stem like base
present in intestinal and respiratory epithelium
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30
Q

epithelium primarily involved in production of specific substances which are extruded from these cells are called glands

A
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31
Q

glands are classified into

A 
exocrine glands (release their products on the epithelial surface)
endocrine ( releae their products into the blood)
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32
Q

exocrine glands are classified on the basis of

A

morphology
nature of secretory products
mode of secretion

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33
Q

describe the morphology of glands

A

glands are supported by stroma of connective tissue
connecitve tissue that encloses the gland is called capsule, septa divides the capsule into lobes
thinner lobules further divide it it into lobules
blood nerve and lymphatics run along the connective tissue septa

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34
Q

describe myoepithelial cells

A

epithelial cells having the ability to contract

secretory protions of some glands are surrounded by these cells

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35
Q

simple tubular gland description and examples

A

secretory portion is a straight tubule

crypts of lieberkuhns (in small intestine)

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36
Q

simple coiled tubular gland and its examples

A

secretory portion is coiled and long

sweat glands

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37
Q

simple branched tubular glands description and examples

A

secretory portion is divided into two or more branches with tubular ends
glands of stomach and endometerial glands of uterus

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38
Q

simple alveolar glands description and examples

A

rounded ac like secretory portion

mucuos glands of penile urethra

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39
Q

simple branched alveolar glands description and examples

A

secretory portion consists of branched saclike secretory parts
sebaceous glands
meibomian glands of eyelids

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40
Q

simple tubulo-alveolar glands description and examples

A

secretory portion consists of branched tubules with sac like alveoli at their distal ends
small salivary glands of oral cavity, mucosal glands of conducting parts of respiratory tract

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41
Q

compound branched tubular glands description and examples

A

secretory portion is branched in long tubules

submucosal glands of duodenum

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42
Q

compound alveolar glands description and example

A

several saclike units with small ducts converge at larger ducts
exocrine pancreas

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43
Q

compound tubulo-alveolar glands

A

ducts of both tubular and alveolar secretory units converge at larger ducts
salivary glands

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44
Q

what is the classification of glands on the basis of mode of secretion

A

merocrine
apocrine
holocrine

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45
Q

describe merocrine secretion and examples of it

A

most common form of secretion
secretory product is exocytosed without any loss of cytoplasm
salivary gland, lacimal gland and intestinal gland

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46
Q

describe apocrine secretion and its examples

A

apical part of cytoplasm is lost along with its secretion
sweat glands located in axilla and perianal area
ceruminous gland of external auditory canal

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47
Q

holocrine secretion description and examples

A

entire cells laden with secretory molecule disintegrates releasing the secretory products
sebaceous glands

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48
Q

describe mucous secretion and its examples

A 
pink 
flat peripheral nucleus 
cellular outline clear
lumen is distinct 
no basal basophilia 
mucin and glycoproteins released
pyloric gland of stomach
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49
Q

serous secretion description and example

A 
thin watery protein rich secretion
bluish purple appearance 
nucleus round and basal 
cell outline not clear
lumen indistinct 
basal basophilic
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50
Q

what is connective tissue

A

diverse group of cells embedded in a tissue specific extracellular matrix

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51
Q

what are the components of connective tissue

A

extracellular matrix
cells
ground substance

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52
Q

classification of connective tissue

A

embryonic CT

adult CT

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53
Q

classification of embryonic CT

A

mesenchym

mucous tissue

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54
Q

classification of adult CT

A

CT proper
cartilage
bon

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55
Q

describe mesencymal CT

A 
primarily in embryo 
spindle shaped cells of uniform size with processes 
Gap junctions 
viscous ground substance
few fine collagen fiber
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56
Q

describe mucous/mucoid CT

A

spindle shaped cells widely separated
gelatinous ground substance
wispy collagen fibers
adult pulp of tooth vitreous chamber of eye nucleus pulposus

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57
Q

classification of CT proper

A

loose CT

dense CT

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58
Q

classification of loose CT

A

areolar

reticular

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59
Q

name the cells of CT

A 
fibroblast 
macrophages 
mast cells 
adipose cells 
plasma cells 
wandering cells
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60
Q

describe fibroblast according to their forms and their function

A

inactive: large / somewhat flattened/ cytoplasmic process/ nucleus is small and deeply basophilic. cytoplasm i slightly eosinophilic
active: cell is enlarged/ more cytoplasmic processes/ nucleus is larger/ cytoplasm is slightly basophilic
produce fibers and ground substance for growth and repair

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61
Q

describe macrophages and their functions

A

phagocytic cells derived from monocytes
irregular shape
short cytoplasmic processes

carry out phagocytosis
antigen presenting cells

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62
Q

describe mast cells and their functions

A

large cells with basophilic granules containing histamine and heparin
show metachromasia in toludine dyes
absent in CNS

63
Q

describe fat cells and their functions

A

large oval cells with signet ring appearance
nucleus is flat and pressed against the cell membrane
specialized to store triglyceride vesicle(s)
in histologic preparation fat is dissolved
white adipose stores fat
brown adipose helps maintain body temperature in newborns

64
Q

describe plasma cells and their functions

A

B- lymphocytes
large ovoid cells with basophilic cytoplasm due to extensive RER
nucleus is spherical and eccentric and chromatin is coarsely arranged in a regular manner against nuclear membrane giving the cell a cart-wheel or clock face pattern
it produces antibodies

65
Q

what are type of fibers found in CT

A

collagen
reticular
elastic

66
Q

describe the structure and classification of collagen fibers

A

made up of collagen proteins (more abundant protein)
formed from tropocollagen (300nm L and 1.5 nm D)
tropocollagen formed of three alpha chains wound together in a helical structure
there are 14 types of collagen (type 1-14)
collagen type 1-3 form fibers while others a non-fibrillar

67
Q

significance of type I collagen

A 
most abundant variety of collagen 
2-10um in diameter 
striations every 64nm
found in dermis/ bones/ fasciae/organ capsule 
eosinophilic appearance
68
Q

significance of type 2 collagen

A

found in hyaline and elastic cartilage/ vitreous body of eye

69
Q

significance of type 3 collagen

A

makes reticular fibers

70
Q

significance of type 4 collagen

A

found in basement membrane

71
Q

write a short note on elastic fibers

A

made up of elastin
elastic property is due to random coiling of molecules
yellow color-highly elastic fibers form loose networks
thinner branching
found in ligamentum flavum / lungs and large arteries

72
Q

significance of type 5 collagen

A

found mainly inn fetal membranes and placenta

73
Q

write a short note on reticular fibers

A

made of type 3 collagen
stain black with silver dyes
form thin networks in highly cellular organs
found in blood vessels/intestine/uterus/urinary bladder
agryophilic

74
Q

what is ground substance

A

amorphous, transparent, semi-fluid gel like substance composed of GAGs, proteoglycans, glycoproteins in which cells and fibers are embedded

75
Q

types of GAGs

A

hyaluronic acid: in loose supporting tissue

sulphate group attached: chondrotin 4, 6/ dermatan/ heparan/ heparin/ keratan

76
Q

describe GAGs

A

long unbranched polysaccharide chains of seven different types of repeating disaccharide units
they are acidic due to hydroxyl, carboxyl, sulphate groups attached to them

77
Q

write a short note on proteoglycans

A

proteins which bind to GAGs

78
Q

write a short note of glycoproteins

A

proteins attached to polysaccharide
adhesve property
provides strength, ridgidity to ground substance
they form binding sites for cell adhesion molecules and ECM molecules
examples include: fibrillin, fibronectin ,laminin, enactin

79
Q

what is the function of ground substance

A 
mechanical and structural support
fills spaces 
lubricant
barrier to large molecules 
facilitates cell growth and information exchange
80
Q

general characteristics and example of loose CT

A

cellular
viscous gel lke ground substance
thin mesh work of collagen and elastin fiber
highly vascular
superficial fascia beneath epithelium
biological packing material for tissues and organs
bind tissues and organs while allowing a considerable degree of mobility
forms stroma of most organs

81
Q

describe reticular CT and its function

A

consists of reticular fibers and reticular cells
reticular cells are stellate shaped and have long cytoplasmic processes and are lodged within meshwork of reticular fibers
form the supporting framework of liver spleen, bone marrow and lymphoid organs
some reticular cell posses fibroblastic activity while others give rise to erythrocytes and leukocytes

82
Q

what is adipose tissue

A

it is composed of adipocytes organized into lobules separated by fibrous septa

83
Q

describe white adipose tissue

A 
UnilocularAdipocytes
(Signet Ring)
Spherical Polyhedral shape, 
Nucleus Flat
Condensed Lipid + Vimentin
Organic Solvent Xylene
Energy Storage /Insulation & Cushioning Of Vital Organs
Lipomas & Liposarcomas
84
Q

describe brown adipose tissue

A

smaller multilocular

nucleus round eccentric

85
Q

general characteristics of dense connective tissue

A

dense packing of fibers
few cell
less ground substance
limited vascular supply

86
Q

dense CT is classified into

A

regular

irregular

87
Q

describe dense regular CT

A

densely packed fibers arranged parallel to each other
flattened elongated fibroblasts present between fibers
occur in the from of tendons, ligaments and aponeurosis
great tensile strength

88
Q

describe dense irregular connective tissue

A

occurs in the form of sheets
thick bundles of fibers run in all directions
occur in areas subject to mechanical stress
some fibroblasts and macrophages are found between fibers
mostly collagen fibers are present but other fibers are also there
form dermis of skin/ capsules of organs(liver, lymph nodes/ perichondrium/ periosteum

89
Q

state general characteristics of tendon

A 
 CORD LIKE
 WHITE INEXTENSIBLE
 CELLS IN ROWS // FIBER
 TENDON CELL
ENDOTENDINEUM,EPITENDINEUM
90
Q

describe general characteristics of cartilage

A

Cartilage is a resilient and smooth elastic tissue that can be found in joints and between bones, rib cage, intervertebral discs, ear, nose etc.
It is not as stiff as bone and much more flexible and elastic.
It is avascular
Cartilage is surrounded by fibrous membrane known as perichondrium which is similar to periosteum in structure and function

91
Q

what is perichondrium and describe its layers

A

Dense layer of fibrous connective tissue covering the cartilage.

Outer fibrous layer. This dense membrane of connective tissue contains fibroblast
cells that produce collagen.

Inner chondrogenic layer. This layer contains fibroblast cells that produce
Chondroblasts and chondrocytes (cartilage cells)

92
Q

which cartilages dont contain perichondrium

A

hyaline articular cartilage and fibrocartilage

93
Q

describe chondroblasts

A

produce the matrix of the cartilage, gets trapped in ECM and become less active in producing ECM, therefore become chondrocytes

94
Q

describe chondrocytes

A

Chondrocytes produce all the structural components of the cartilage such as
collagen, proteoglycans, glycosaminoglycan and helps in repair of matrix

95
Q

what are the types of cartilages

A

Hyaline Cartilage
Elastic cartilage
Fibrocartilage

96
Q

what are the characteristics of hyaline cartilage

A

It has thin fibres which are not seen in matrix.
Have bluish glassy appearance because of presence of Chondroitin
Sulphate.
It is quite flexible
Contains type ll collagen
Precursor of bone.
Example: Trachea, nose, larynx, ribs

97
Q

what are the characteristics of elastic cartilage

A 
It has numerous yellow elastic fibres.
Colour is yellow and appearance is opaque.
Contains type ll collagen
Maintains the shape of the structure.
Example: epiglottis, external ear
98
Q

describe the general characteristics and name examples of fibrocartilage

A

Type of cartilage with numerous white fibres
Colour is glistening white and appearance is opaque
Only cartilage that contains Type l in addition to Type ll collagen
Example: Symphysis pubis, ligaments

99
Q

what are the general properties of muscle cells

A

excitability
extensibility
elasticity
contraction

100
Q

muscles are classified on the basis of ——-

A

striated

non striated

101
Q

striated muscles include

A

skeletal muscle
cardiac muscle
visceral striatedd

102
Q

describe the characteristics of skeletal muscle cell

A 
mesenchymal in origin 
variable length (1mm-35cm)
CT supplies nerves and blood vessels 
diameter varies (10-100um)
cylindrical shape with rounded ends
multinucleated/ ovoid shape/ peripherally located close to the sarcolemma
cytoplasm filled with myofibrils running parallel to the cell axis
striations seen
103
Q

describe characteristics of skeletal muscle

A

muscle fibers grouped into bundles called fasciculi

muscle fiber is surrounded by endomysium

fasciculi separated form each other by perimysium

whole muscle is surrounded by dense sheath of supporting tissue called epimysium

104
Q

describe the characteristics of myofibril

A

show alternating light and dark bands

composed of thin (actin 5-7nm diameter and 1.5 um length) and thick filaments (myosin 12-16nm diameter and 1.5um length)

myofibrils arranged parallel to the axis of myofibrils

M line is where mysoin filaments are centrally attached

Z line is where actin is centrally attached

myosin is attached to z line by titin

area between two Z lines is called sarcomere

Central area of sarcomere containing myoin filaments is called A band

while the area bisceted by Z line free of mysoin is called I band

the area where actin and mysoin dont overlap is called H band

105
Q

describe the structure of actin filament

A

two actin chain round into a double helix

tropomysoin is wound around actin helix and rest in the double helix groves

tropomyosin masks actin binding sites

troponin complex has three subunits I, C, T

106
Q

functions of troponin subunits

A

I subunit for interaction between actin and troponin

C subunit for binding of calcium

T subunit for binding to tropomyosin

107
Q

describe the structure of mysoin filament

A

mysoin filaments are made up of myosin proteins

myosin protein has 2 heavy and two light pairs

heavy chain forms the head and the arm of myosin

light chain stablizes the head

108
Q

describe key characteristics of sarcoplasmic reticulum and sarcolemma

A

t-tubules: sarcolemma form tubular extension of ECF which transverse into muscle fiber

between T-tubules is the sarcoplasmic reticulum which forms a cistern on each side of the T-tubule called terminal cisternae

the T-tubule along with the terminal cisternae is called triad

sarcoplasmic reticulum stares calcium ions

109
Q

describe the blood supply to skeletal muscles

A

large blood vessels enter epimysium, divide ramify throughout the perimysium, branches from the perimysial arteries transverse along the long axis of muscle fibers (capillary beds from around the muscle fiber)

110
Q

describe nerve supply to the skeletal muscle

A

innervated by large motor neurons

a single motor nerve fiber and muscle fibers supplied by it are referred to as motor unit

111
Q

difference between slow and fast muscle fibers

A

slow/type1/ red muscle fiber:

perform aerobic work 
slow fibers
abundance of myoglobin
small in cross-section
numerous mitochondria
rich in blood supply 
resistant to fatigue 
slow contraction
bulky muscle of thigh and leg

fast/white/type 2

anaerobic work 
fast fibers
less myoglobin 
large in cross-section
contain less mitochondria 
relatively poor blood supply
fatigue rapidly 
rapid contraction 
triceps' and biceps
112
Q

describe cardiac muscles

A

involuntary but striated
branched syncitium with intercalated discs
collagen tissue supports extremely rich capillary network

113
Q

describe cardiac muscle fibers

A

striation similar to skeletal muscle
length is about 100um and 15um diameter
single or two nuclei preset centrally
sarcoplasm is more abundant
myofibril form a branched myofibrillar network separated by rows of cytoplasm containing rows of mitochondria and sarcoplasmic reticulum
fat, glycogen and lipofuscin pigment granules seen

114
Q

describe the sarcoplasmic reticulum and T-tubules in cardiac muscle cells

A

T-tubules lie at the level of Z line
they have greater diameter
terminal cisternae are not formed so triad is not well formed
cisterns narrower with frequent anastomoses

115
Q

describe the structure of intercalated discs

A

darkly staining areas (o.5-1um) thick
mark the boundary of cell
interdigitate with other cells
always concede with Z line

116
Q

how does the structure of intercalated discs relate to the functioning of cardiac muscle cells

A

these discs bind the cells
transmit forces of contraction
provide area of low electrical resistance for rapid spread of action potential throughout the myocardium

117
Q

which types of cell junctions are present in intercalated discs

A

fascia adherens
macula adherens (desmosomes)
gap (nexus) junctions

118
Q

describe fascia adherens

A

actin filament at the end of terminal sarcomeres insert into fascia adherens and transmit contractile forces from cell to cell

119
Q

describe macula adheren

A

are less frequent and provide anchorage for intermideate filaments of cytoplasm

120
Q

describe gap junctions

A

are sites of low electrical resistance through which impulse pass rapidly from cell to cell

121
Q

describe blood supply of cardiac muscles

A

more extensively supplied than skeletal muscles

an extremely rich network of capillaries surround the muscle

122
Q

describe nerve supply of cardiac muscle

A

supplies by sympathetic and parasympathetic nerves of autonomic nervous system

123
Q

describe the differences between skeletal muscles and cardiac muscles

A 
SK:
cylindrical shape
well defined striations
intercalated disc absent 
less mitochondria 
T tubules A I band 
terminal cisternae are dilated 
Triad present 
CM:
branched syncitium 
striations present 
single central nucleus 
intercalated disc present 
mitochondria are more
T tubules are present near Z line
terminal cisternae are absent 
Diad present
124
Q

describe the structure of smooth muscle

A

donot show striations

found in blood vessels and viscera

125
Q

describe smooth muscle cell

A

spindle shape
diameter 3-8um
length 15-500um
ovoid nucleus located in the central
usually arranged in sheets
densely packed parallel to each other
no myofibrils are present
myofilaments are longtitudinally arranged in cytoplasm and are not as orderly as in skeletal muscle
mechanism of contraction is the same as in skeltal muscle
instead of Z lines there are dense bodies contiaing alpha actin
organelles are mainly concentrated around nucleus
no T tubules but cavelae present in sarcolemma

126
Q

describe nerve supply of smooth muscle cells

A

multiunitary tye: rich nerve supply- nearly all muscle cells nrecievnerve terminals
example muscles of iris, ductus differens , large arteries unitary : much fewer nerve terminals. adjacent smooth muscle fibers joined together by gap junctions so implses pass from one cell to the next

they are innervated by autonomic nervous system

127
Q

describe blood supply to smooth muscle

A

not s richly supplied as striated muscle, which is why they appear pinkish white

128
Q

nervous system is classified into

A

CNS (brain and spinal cord)

PNS (all other nerves)

129
Q

nervous system is functionally divided into

A

somatic nervous system (voluntary functions)

autonomic nervous system (control involuntary functions)

130
Q

describe the characteristics of nervous tissue

A

nerve cell (structural and functional unit of nervous system) and supporting cells (protect, nourish , maintain neuron)

131
Q

describe the general characteristics of neuron

A 
cell body (soma/perikaryon)
processes (axon/dendrites)
132
Q

describe the classifications of neurons

A

morphological
functional
according to length of axon

133
Q

describe morphological classification of neurons

A

unipolar: only one process (axon) e.g. mesencephalic nucleus of 5 cranial nerve
bipolar: have two process on opposite sides(axon and dendrite) e.g. cochlear neurons , vestibular ganglia, retina and olfactory epithelium

pseudo-unipolar: one process that divides into two branches close to the cell body (axon-CNS/ dendron-periphery) e.g. dorsal root ganglia neurons

multipolar: single axon and multiple dendrites e.g. pyramidal cells of cerebral cortex, purkinji cells of cerebellar cortex, anterior horn cells of spinal cord

134
Q

describe function classification of neurons

A

sensory neuron: receive sensory stimuli and pass them to CNS

motor neurons: controls the effector such as muscles and glands

interneurons: connect neurons to form complex functional circuits

135
Q

describe the classification of neruon on the basis of length of axons

A

gogi type 1: long axon that leave the gray matter and passes to other regions of CNS via white matter or leaves the CNS to become a peripheral nerve e.g. Pyramidal cells of cerebral cortex, anterior horns of spinal cord

golgi type 2: short axons which donot leave the part of gray matter in which the cell body of neuron lies . these are numerous in cerebral and cerebellar cortex and most function as interneurons

136
Q

describe cell body of neuron

A

contains nucleus
nucleus is surrounded by cytoplasm
soma may be 4um in diamter (granule cells of cerebellar cortex) or as large as 135um (anterior horn of spinal cord)
shape varies according to number, orientationn of its processes
globular in pseudo-unipolar
fusiform in bipolar
stellate in multipolar

137
Q

describe nucleus of neuron

A 
single
large 
pale staining
centrally placed
nucleolus is prominent
138
Q

describe cytoplasm of neuron

A

contains organelles
basophilic nissl granules (RER and ribosomes) present except in axon hillock
microfilaments and neurofilaments are present

139
Q

describe the properties of axon

A

single process
uniform contour
variable length
cytoplasm of axon is axoplasm
plasma membrane of axon is axolemma
side branches are called collaterals
axon dividing into multiple branches is called telodendria
axon collaterals and terodendria from small knob at their ends called terminal buttons
terminal button form synapses
golgi and nissl substances are absent
contains mitochondria, neurofilaments, microtubules, SER

140
Q

describe the properties of dendrites

A

afferent process
contain all soma contents except golgi body
present at the sites ofsynaptic contacts

141
Q

describe mylelinated nerve fibers

A

nerve fibers covered with myelin sheath (composed of lipoprotein myelin)
it is formed by schwann cells in PNS and oligodendrocytes in CNS around he axon
contains nodes of Ranvier
internode is the area between two nodes

142
Q

what is the fnction of myelin sheath

A

provides insulation to axon

speeds up the rate of conduction by allowing action potentials to jump from one node to the next (saltatory conduction )

143
Q

describe non myelinated nerve fibers

A

not convered by myelin sheath
in PNS unmyelinated axons lie in clefts formed by invaginations of schewann cell plasma membrane by the axons
a single schewann cell cell lodges many axons
a ingle unmyelinated nerve axon passes through clefts of a number of schewann cells
in CNS unmyelinated axons are not ensheathed an run fee

144
Q

describe the classifcation of synapses

A

axodendritic : between axon and dendrite

axosomatic : between axon and soma

axoaxonic : between two axons

dendrodendritic : between two dendrites

145
Q

describe the structure of nerve

A

nerve fiberes are enclosed within endoneurium

pernurium enclosed fascicles of nerve fibers

endoneurium encircle the whole nerve and contain perineurium

146
Q

describe neuroglia and their types

A

they are supporting cells of CNS

they are of two types
neuroglia proper and ependyma

147
Q

describe the type of neuroglia proper

A

astrocytes
protoplasmic astrocytes
fibrous astrocytes

148
Q

describe the properties of astrocytes

A 
Largest, most numerous 
Long processes expanded pedicles
Protoplsmic & fibrous
Spherical  central euchromatic  nucleus
Lightly stained cytoplasm 
Functions 
Supportive
Cover bare areas (nodes of ranvier, synaptic clef
Scar tissue
Movement of metabolite & waste
Maintain chemical environment
Regulation of extracellular environment 
Blood brain barrier
149
Q

describe protoplasmic astrocytes

A

grey matter

short thick processes with many branches

150
Q

describe fibrous astrocytes

A

white matter
long slender smooth
fewer processes
scarring cells

151
Q

describe oligodendrocytes

A

both gray and white matter
myelination of CNS
produces myelin for several cells

152
Q

describe microglia

A

mesenchymal in origin
short banching processes
phagocyticcells

153
Q

describe ependymal cells

A

simple cuboidal epithelial cells that line the cavities of brain and spinal cord
apical surfaces possess microvilli
they are fluid transporting cell
from junctional complexes

CBA- 1 (8 decks)

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