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Histology Midterm
Integumentary System
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General Characteristic of Integumentary System:
Integument/
Cutaneous
layer
Largest
single organ of the body
15-20
% of total body weight
Functions of skin:
Protection
Sensory
Thermoregulatory
Metabolic
Sexual
signaling
It covers the palms and soles (400 to 1400 micrometer)
Thick skin
It covers the whole body except palms and soles (varies from 75 to 150 micrometer)
Thin skin
Characteristics of Epidermis:
Stratified squamous
keratinized epithelium
lack
vasculature
receive nutrients from the
dermis
Keratinocyte
Primary
cells
Located at the
epidermis
Originate the
stratum basale
and move up to the final barrier of the skin,
stratum corneum
Melanocyte:
Located at the
basal
epidermis
Neutral
crest derived
Pale-staining
, rounded cell bodies
Synthesizes
dark
melanin
pigment in
melanosomes
Protects
nuclear
DNA
from
UV
damage
Disease related to melanocyte:
Albinism
and
vitiligo
It is brown or black pigment; found in hair follicle
Eumelanin
Termed as red hair
Pheomelanin
A condition wherein the less melanin than usual in the body; condition that leads to having very light skin, hair and eyes.
Albinism
It is due to defect in the enzyme
tyrosinase
Albinism
A disorder that cause patches of skin to lose pigment or color; happens when melanocyte are attaked and destroyed
Vitiligo
Three general layers of the skin:
Epidermis
Dermis
Hypodermis
(subcutaneous layer)
What are the cells present in epidermis?
Keratinocyte
Melanocyte
Langerhans
Merkel cell
Responsible for sensing gentle touch?
Merkel cell
What is the pigment that produced by melanocyte?
melanin
It is decrease activity of melanocyte
Vitiligo
Where does the langerhans cell located?
Stratum spinosum
Langerhan cells
:
Antigenic
presenting cell
2-8
% of cells in epidermis
Bind
,
process
and
present antigen
to
T-lymphocytes
Aka Epithelial Tactile Cells
Merkel cells
Merkel cells:
Mechanoreceptors
for light touch
Abundant in
fingertips
and
bases
of some hair follicles
Small, golgi-derived dense-core
neurosecretory
granules containing
peptides
Where does the melanocyte is located?
basal epidermis
or
stratum basale
Neural crest derived
Melanocyte
Layers of the Epidermis:
All layers have
thick
and
thin
skin except
Stratum lucidum
which has
thick
skin only.
Enumerate the layers of the epidermis:
Stratum
corneum
Stratum
lucidum
Stratum
granulosum
Stratum
spinosum
Stratum
basale
It is keratin-filled keratinocyte
squames
Stratum corneum:
15-20
layer of dead, flattened, anucleate, keratin-filled called
squames
Layer of
dead keratinocytes
Bound by
hydrophobic lipid-rich segment
which provides protection against
water loss
and
friction
What are the layers of skin that have function of protection of Water loss?
Stratum corneum
and
Stratum granulosum
What are the functions of squames?
Protection
for
friction
and
water loss
How many layers of anucleate dead cells in stratum lucidum?
2-3
layers
Stratum granulosum:
3-5
layers of
keratinocyte
Contains
kerato-hyaline
granules
intensely
basophilic
Contains
lamellar
granules
which produces lipid-rich impermeable for barrier against water loss
It is lipid-rich impermeable layer around the cells forming a major part of the skin's barrier against water loss
lamellar granules
Considered as thickest layer among stratums
Stratum
spinosum
Stratum spinosum:
Thickest
layer
Consists
polyhedral
cells having central
nuclei
with
nucleoli
and
cytoplasm
actively synthesizing
keratins
Several layers of
keratinocyte
all joined by
desmosomes
Contains
tonofibrils
,
prickle
cells
Cells may still
divide
Contains Stratum
germinativum
It binds to our desmosomes thus forming spines between keratinocytes in the stratum spinosum
tonofibrils
Structure present in the stratum spinosum that causes keratin or prickle
tonofibrils
Keratinocytes in our stratum spinosum
Prickle cell
Where does mitosis occurs?
Stratum
basale
Stratum basale:
Single
layer of
cuboidal
to low
columnar
cells in contact with
basement
membrane
Mitosis
occurs
Melanocytes
and Merkel cell also present
Where does merkel and melanocyte are present?
Stratum
basale
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