Histology Flashcards
What is the definition of Ectoderm?
Gives rise to the epithelia of the skin and its associated glands , and the oral, nasal and anal passages
What is the basal lamina ?
At epithelia basal surface, its a sheet like structure composed of extracellular matrix components called basal lamina
what is apocrine secretion?
Membrane bound vesicles (including secretory product ) are pinched off from the cell into ECS still surrounded by membrane
- occurs at apex
- product is lipid rich
What are the 3 main classes of filaments that form the cytoskeleton?
- microfilaments (5nm in diameter)
- intermediate filaments (10nm)(main structural component)
- microtubules (25nm)
What common features do all epithelia cells have?
- Basal lamina
- All are non-vascular nutrients from capillaries in underlying tissue must diffuse across the basal lamina
- usually polarised -apical and basal ends differ
- tend to bind together in sheets
What are the functions of epithelia?
- mechanical barrier
- chemical barrier
- Absorption
- Secretion
- Containment
- Locomotion
- Minor functions i.e sensation, contractility
Where is the product secreted in exocrine glands?
-Product secreted towards the apical end of the cell either into the lumen of an internal space, into a duct, or onto the body surface. Termed “ducted” glands
Give examples of endocrine glands?
- Pituitary
- Thyroid
- Thymus
- Pancreas
- Adrenal glands
- ovaries/ testes
Name and describe the 3 types of secretory product?
- mucous gland - secretes mucus
- serous gland- secretes a fluid
- mixed gland - produces both mucus and watery secretions
What 4 things are covering epithelia based on?
1) cell shape
2) number of layers
3) cell surface , or tissues surface , specialisations
4) The presence of any specialised cell types
Exocrine glands are classified on the basis of what 5 things?
1) Mechanism of release of secretory product
2) Type of secretory product
3) Number of secretory product
4) Duct morphology
5) Arrangment of secretory cells
Give examples of exocrine glands.
- Lacriminal glands
- Salivary
- Mammary
- Liver
- Pancreas
- Brunner’s
- Sweat
- Sebaeous
Name 3 types of secretory cells
- Tubular
- Acinar
- Tubulocinar –> secretory tubules , or tubules ending in acini
What are desmosomes and what do they do?
- Link submemnrane intermediate filaments of adjacent cells (macula adherent)
- Provide mechanical stability to the skin
What is epithelia composed of?
Closely aggregated polyhedral epithelial cells with a minimum of intercellular substance (little space between cells)
What 3 types of cell shapes are there?
- Squamous(flat)
- Cuboidal (cube)
- Columnar (column)
What is tonicity and what 3 types are there?
The effect a solution has on cell volume
1) Isotonic - no change
2) Hypotonic- water diffuses into cells and it swells
3) Hypertonic - water diffuses out of the cell and it shrinks
What are the 3 types of cell/tissue surface?
- prominent microvilli (“brush border”)
- cilia
- Keratinized (presence of layers of keratin proteins on the tissue surface)
What 3 embryological germ layers are there that give rise to epithelial cells?
1) Ectoderm
2) Mesoderm
3) Endoderm
What is holocrine secretion?
- occurs when whole secretory cells are from epithelium and disintegrate , discharging their contents
- product is lipid rich
What is the definition of mesoderm?
Gives rise to the epithelial linings of cardiovascular system ( termed endothelium) and to the mesothelium lining the peritoneal , pleural and pericardial cavities
Name 3 types of layers of epithelia?
- ‘Simple’- one layer
- ‘stratified’ - two or more layers
- ‘Pseudostratified’ - looks like multiple layers but intact all in contact with the basal lamina
What is the product secreted in endocrine glands?
Product secreted toward the basal end of the cell (end sitting on the basal lamina), then distributed by the vascular system throughout the body. Termed “ductless” glands
What is memocrine secretion?
-occurs by exocytosis at apex of the cell
