Histology Flashcards
what is the overview from smallest to largest in regards to cytology
cells
tissues - a conglomeration of cells for specific function
organ - a conglomeration of tissues serving multiple functions
function of nucleus
cells genetical material
control activity of cell
what is the nuclear envelope?
double membrane that encloses entire nucleus separating it from cytoplasm
function of nucleolus
assembly of ribosomes by translating mRNA and make proteins
what is the cytoplasm / purpose
outermost component of cells that contains organelles
mitochondria purpose
generate ATP
purpose of smooth ER
steroid synthesis
rough ER purpose
protein synthesis / ribosomes
golgi apparatus function
process and package macromolecules (proteins/lipids) after synthesis
lysosomes function
contain enzymes for digestion
cell’s garbage system
what are the four tissues
epithelium, connective tissue, muscle, nerve
generally where can the epithelium be found?
line the cavities and surfaces of structures
function of epithelium (4)
- seperates internal cell / external environment
- homeostasis through barrier that allows for permeability
- formation of glands
- lies on top of connective tissue separated by basement membrane
Features of epithelia (7)
highly cellular
avascular
nervous innervation for sensation
rapid cell turnover
basement membrane
junctional complexes
polarized
what are the types of junctional complexes? what are they?
tight junction - impermeable
gap junction - allows passage of small molecules
desomosome - joins intermediate filaments in one cell to another
adhering junction - joins actin bundle in one cell to
what is apical polarization
directed toward exterior surface or lumen
what is lateral polarization
contacts and communicates with adjacent cells
what is basal polarization
rests on basement membrane anchoring cell to underlying connective tissue
functions of epithelia (5)
protect
transport
secretion
absorption
sensation
classifications of epithelium
simple
stratified
pseudostratified
what is simple epithelium
one cell thick, in contact with underlying basal lamina
what is stratified epithelium
multilayered
what is pseudostratified epithelia
simple columnar epithelia cells who nuclei appear at different heights
where is simple squamous epithelia normally found
alveoli, blood vessels, esophagus, anus
where is cuboidal epithelia normally found
secretive or absorptive tissue
ex - pancreas, kidney tubules, ovary and testes
what is columnar epithelium
elongated, column shaped
what does the columnar epithelium do? what specifically can be found in it?
secretes mucous
Goblet Cells
what are goblet cells
unicellular glands between cells of parts in the intestine
what is the transitional epithelium’s other name?
urothelium
where can transitional epithelium be found? what does it do?
urinary bladder
allows for stretching of bladder
what is keratinized epithelium
most apical layers of cells are dead and do not have nucleus or cytoplasm. contain keratin, making them waterproof
what is an example of keratinized epithelium?
skin - keratinized stratified squamous epithelium
what is cilia?
elongated extensions of cytoplasm that move material along cell surface
what are microvilli?
elongated finger-like projections of the cell membrane that increases surface area for absorption / secretion
where can cilia be found? where can microvilli be found?
fallopian tube
small intestine
functions of skin? (7)
protection
water resistance
sensation
heat regulation
control evaporation
storage and synthesis
absorption
what is the epidermis? what are contained within the epidermis?
outermost layer of the skin
merkel cells, keratinocytes, melanocytes and langerhans cells
is the epidermis vascular?
no
what is the dermis?
a layer below epidermis that consists of connective tissue
what is the main function of the dermis?
cushion the body from stress and strain
where is the dermis connected? what connects it?
connected to the epidermis by basement membrane
what can nervous tissue can be found in the dermis? what is their purpose?
mechanoreceptor nerve endings
sense of touch and heat
what else can be found in the dermis?
hair follicles
sweat glands
sebaceous glands
lymphatic vessels
blood vessels
what are the divisions of the dermis?
papillary reticular
what is the papillary dermis?
superficial area adjacent to the dermis
what is the reticular dermis?
deep thicker area below papillary dermis
what are the sublayers of the epidermis?
stratum:
corneum
lucidum
granulosum
spinosum
basale
what is the stratum corneum?
heavily keratinized flat cells with no nucleus / cytoplasm
what is the stratum lucidum? what is special about it?
only in thick skin (soles of feet/hands)
what is the stratum granulosum? what is in it and how thick is it?
2-4 layers of flattened cells holding keratohyalin granules
what is found in the stratum spinosum?
post-mitotic keratinocytes
what is the stratum basale?
deepest layer where cell division occurs; resting on basal lamina
where are melanocytes found?
stratum basale
what are keratinocytes?
predominant cell types that synthesize keratin
what are melanocytes
located in stratum basale that synthesize melanin
what are langerhans cells? what layer of the epidermis can they be found?
located in stratum spinosum containing large granules (birbeck) that become fully functional antigen-presenting cells in immune defense
what are merkel cells
specialized cells associated with sensation of light tough and discrimination of shapes/textures
what is the inflammatory phase?
blood clot formation to obtain hemostasis
what are the 4 things that occur during the proliferation phase?
angiogenesis, collagen deposition, granulation tissue formation, epithelialization and wound contraction
what occurs in the maturation and remodeling phase
collagen is remodeled and realigned along tension lines and cells that are no longer needed are removed
what is the epidermis made of
stratified squamous epithelium
