Histology: Epithelial Tissue Flashcards
Types of tissue: 4 primary types
- Epithelial tissue
- Connective tissue
- Muscle tissue
- Nervous tissue
Integumentary system: (2)
- Encloses internal body structures
- Site of many sensory receptors
Hair, Skin & Nails
Skeletal system: (2)
- Supports the body
- Enables movement (with muscular system)
Cartilage, bones, joints
Muscular system: (2)
- Enables movement (with the skeletal system)
- Helps maintain body temperature
Skeletal systems, tendons
Nervous System: (2)
- Detects and processes sensory information
- Activates bodily responses
Brain, spinal cord, peripheral nerves
Endocrine system: (2)
- Secretes hormones
- Regulates bodily processes
The pituitary gland, thyroid gland, pancreas, adrenal glands, testes, ovaries
Cardiovascular system: (2)
- Delivers oxygen and nutrients to tissues
- Equalizes temperature in the body
Lymphatic system: (2)
- Returns fluid to blood
- Defends against pathogens
Thymus, lymph nodes, spleen, lymphatic vessels
Respiratory system: (2)
- Removes carbon dioxide from the body
- Delivers oxygen to the blood
Nasal passage, trachea, lungs
Digestive system: (2)
- Processes food for use by the body
- Removes wastes from undigested food
Stomach, liver, gall bladder, large intestine, small intestine
Urinary system: (2)
- Controls water balance in the body
- Removes wastes from the blood and excretes them
Kidneys, Urinary bladder
Male reproductive system: (2)
- Produces sex hormones and gametes
- Delivers gametes to the female
Epididymis, testes
Female reproductive system: (3)
- Produce sex hormones and gametes
- Supports embryo/fetus until birth
- Produces milk for infant
What are neurons?
Specialised cells send, transport, and receive information through electrochemical signalling.
Supporting cells: ____ cells.
glial
Bundle of neurons = _____.
NERVES- Brain concentration of nerve tissue control movement through muscles—detect sensory stimuli and direct activities in the body Brain and Spinal cord.
Groups of long thin muscle cells → muscle fibres, what do they do?
Contract to allow body and internal organs to move
What are the types of muscle? (3)
Cardiac muscle
Skeletal muscle
Smooth muscle (visceral organs such as intestines)
What is the structure of epithelial tissue?
Polarised with an apical surface that faces the lumen. The basal surface is located interior to thin sheets of cells, tightly packed.
Simple → single layer
Stratified → ____ layers.
Multiple
The shape of epithelial cells: (3)
Squamous (flattened), cuboid, columnar
The function of epithelial cells: (5)
- Provides a barrier against injury, infection, and water loss
- Some absorb or secreted
- Skin
- Linings of internal organs and body cavities
- Linings of intestines (secretory function)
What is connective tissue composed of?
Composed of cells within an extracellular matrix.
Proper connective tissue: (2)
Loose connective & dense fibrous connective tissue
Specialised connective tissue: (4)
- Adipose/fat
- cartilage,
- bone
- blood
Structure varies greatly with function
Tendons are made of _____ connective tissue; ____ transports
Tendons Ligaments Bone; Blood Adipose/fat _____
fibrous
blood
cartilage
What are tight junctions? (2)
Tight junctions
• Seal plasma membranes tightly together
• Digestive tract lining, bladder lining
What are the adhesion junctions/spot desmosomes? (3)
- Permit some movement between cells
- Allow tissues to stretch and bend
- Skin
What are gap junctions? (2)
- Protein channels enable the movement of materials between cells
- Liver, heart
What is a basement membrane? (2)
- Noncellular layer directly beneath epithelial tissue
- Composed of proteins secreted by epithelial cells and connective tissue
What are the functions of the basement membrane? (2)
- Provides structural support to overlying cells.
- Attaches epithelial layer to underlying tissues
What do simple epithelial cells line? (3)
single layer adapted for diffusion—>lines
- lines glands
- respiratory
- digestive & reproductive systems
What do stratified epithelial cells line?
multiple layers—> adapted for protection—> skins
Derived from primary body tissue: (5)
- Ectoderm
- Mesoderm
- Endoderm
- Lining of cavities and surfaces
- Anchored by basement membrane
The polarity of Epithelia:
- All epithelia are polarized—>have two different sides
What is the apical surface?
- The apical surface—> faces the lumen (cavity)/outside of the organ and is therefore exposed to fluid or air.
- Specialised projections—> cover _____.
surface
What is the apical surface of the epithelium lining the small intestine?
- apical surface of the epithelium lining the small intestine is covered with microvilli, (projections that increase the surface area available for absorbing nutrients.)
- Opposite the apical surface of each epithelium—>_____ surface.
basal
What is the shape of simple squamous epithelial?
Shape: Thin, leaky, platelike
What are the shapes of the nuclei of simple squamous epithelial cells?
Nuclei: horizontally flattened & elliptical
Where are simple squamous epithelial cells located? (4)
Location: Lungs, Blood vessels (endothelium), Heart (Mesothelium), Major cavities
What is the function simple squamous epithelial?
Function: Exchange nutrients and gasses by diffusion
What is the shape of simple cuboidal epithelial cells?
Shape: Dice shaped
What is location function of simple cuboidal epithelial cells? (2)
Location:
- Epithelium of exocrine glands of the pancreas,
- Kidney tubules
What is the function of simple cuboidal epithelial cells?
Function: Specialised for secretion
What is the function of the simple columnar cells?
Shape: Goblet cells
What is the location of simple columnar epithelial cells? (2)
Location: Lining of the stomach, Lining of intestines
What is the function of simple columnar epithelial cells?
Function:
- Specialised: sensory reception (nose, ears & taste buds)
- Secrete digestive juices
- Absorb nutrients
What is the shape of stratified squamous cells?
Shape: Multi-layered
What is the location of stratified squamous epithelial cells? (5)
Location: Urothelium (bladder, ureter & urethra), Outer skin, Linings of mouth, anus & vagina.
What is the function of the stratified squamous epithelial cells? (2)
Function: Specialised keratinised Transitional (i.e. stretchy) Withstands damage and waterproofing
What is the shape of stratified cuboidal epithelial cells?
Shape:Multiple layers of cube-shaped cells.
Only the most superficial layer is made up of
cuboidal cells, and the other layers can be
cells of other types.
What is the location of stratified cuboidal epithelial cells? (3)
Location:
Sweat glands
Mammary glands
Salivary glands
What is the function of stratified cuboidal epithelial cells? (3)
Function :
- Protect areas such as the ducts around these glands
- Sometimes involved in secretion
- Act as a filter when separating to distinct areas
What is shape the stratified columnar epithelial cells?
Shape: Multiple layers of column shaped cells
What is the location of stratified columnar epithelial cells? (3)
Location: Rare kind of epithelium, Male urethra, Ducts of some glands
What is the function of stratified columnar epithelial cells?
Secretes and protects
What is the shape of pseudostratified epithelial cells?
Shape: Pseudo → single layer of cells of varying height Nuclei at different heights, so it gives an illusion that its stratified but it isn’t
True or false
Cilia are not energy dependent
False, cilia are energy-dependent.
What is the location of pseudostratified columnar epithelial cells?
Location: Airways (nose & bronchi), Uterus Fallopian tubes
What is the function of pseudostratified epithelial cells? (3)
Function:
- Forms mucous membrane
- Lines portions of the respiratory tract
- Cilia sweep film of mucous along the surface
What is keratinized epithelia?
In keratinized epithelia, the most apical layers (exterior) of cells are dead and lose their nucleus and cytoplasm. They contain a tough, resistant protein called keratin. This specialization makes the
epithelium waterproof, and it is abundant in mammalian skin. The lining of the oesophagus is an example of a non-keratinized or moist stratified epithelium.
What is transitional epithelia?
Transitional epithelia are found in tissues that stretch and it can appear to be stratified cuboidal when the tissue is not stretched, or stratified squamous when the organ is distended and the tissue stretches. It is sometimes called the urothelium since it is almost exclusively found in the bladder, ureters, and urethra.
What is glandular epithelium?
- Glandular epithelium—> group of tissues, other than the covering and lining epithelium—> specialized for the production and secretion of various macromolecules.
What is secretory epithelium?
- Secretory epithelium—> lies beneath the covering and lining epithelium (stratified cuboidal epithelium) —> either consists of cells with specific functions or comprise specialized organs—> glands.
What is a gland?
- A gland—> epithelium that secretes substances into ducts (tubes), onto a surface, or eventually into the blood in the absence of ducts.
-Some unicellular glands, comprised of specialized cells, might be interspersed between the: (3)
simple cuboidal
simple columnar
and pseudostratified epithelia.
What are exocrine glands?
- Secrete their products into ducts that release the secretions onto the surface of organs —> the skin surface or the lumen of a hollow organ.
What do exocrine glands remain connected to?
- Remain connected to the covering epithelium via tubular ducts—> lined with lining epithelium and carry the secreted products into the site of action.
What are endocrine glands? (2)
- Group of glands that do not have a duct system—> release their secretions directly into the bloodstream.
- The secretions—> hormones, enter the interstitial fluid and then diffuse into the bloodstream without flowing through a duct.
Endocrine secretions have far-reaching effects—> distributed throughout the body by the ______.
bloodstream
Epithelium Diseases & Disorders
Skin diseases most common: (8)
- Acne, dermatitis, impetigo (bacterial skin infection), psoriasis (red, itchy, scaly patches on skin),
sunburn, sweating disorders, yeast infections of the mucous membranes, leprosy
How does sunburn work? (3)
> Melanocytes produce melanin → distribute to keratinocytes (common type of skin
epithelium).
When exposed to sun, melanocytes increase production of melanin to
protect cell.
Once cells are damaged → signal molecules generated → body mounts an
inflammatory response → results in “burn” from sun → blood flows to area to repair
damage.
What does sunburn cause damage to?
Sunburn: radiation causes damage to DNA (directly or via free radical excitement)
