tissues Flashcards
(31 cards)
what is the location and function of 3 types of simple epithelium?
forms lining or body cavities
thin layer for fast absorption, secretion and filtration
squamous - blood vessels
cuboidal - kidney
columnar - gut/ ovary
what is the location and function of 4 types of stratified epithelium?
stratified squamous (thick) - for protection, withstands abrasion e.g. skin
stratified cuboidal - exocrine glands
pseudostratified columnar - secretion and movement in the trachea.
transitional - permeability barrier and stretchability in the urinary tract
describe the membrane that all epithelial tissue lay on
Basement Membrane - which is made up of two lamina:
Basal Lamina - upper layer on which the epithelium sits
Reticular Lamina - lower layer
what does apical mean?
side of the epithelium that faces the lumen
what are the 4 junctions?
Desmosomes (macula adherens) - firm anchorage
Tight junctions (occluding junctions) - seals intercellular spaces
Gap junctions - cell to cell communication
Hemidesmosomes - connects the basal layer of epithelium to basement membrane
what is the difference between endocrine and exocrine glands?
Endocrine glands - glands that are cut off from the surface during epithelium development and they secrete into the bloodstream.
Exocrine glands - glands that are connected to the surface during epithelium development and they secrete into tubes.
what 2 shape types can exocrine glands be subdivided into?
Simple ( Tubular & Acinar )
Compound ( Tubuloacinar or separate)
what 2 product secretion types can exocrine glands be subdivided into?
mucous glands - proteoglycans and water secretion in the trachea and gut
serous glands - protein-rich and water/ enzyme secretion in the pancreas
what are the 3 mechanisms of exocrine secretion?
Merocrine - gland stays whole (exocytosis of vesicles) most common type. e.g. sweat glands
Apocrine - pinched off a portion of the gland
e.g. mammary glands
Holocrine - gland dies and becomes secretory product e.g. sebaceous gland
what type of glands is the pancreas made up of?
an organ that is both an exocrine and an endocrine gland.
what is the pancreas made up of?
exocrine glands - pancreatic acini
endocrine glands - islet of Langerhans, excretes insulin and glucagon into the bloodstream
what are myoepithelial cells?
they have contractile functions around acini glands, helping them expel their secretions from the lumen.
what could happen when things go wrong with the function of epithelial cells? 5
Over/ under proliferation
Over/ under secretion
Loss of cilia or villi
what are the abnormal functions of uterine tube glands i.e. mucus production?
chlamydia trachomatis (STD) infects uterine tube - makes mucus thick
infertility
trapping of ovum/sperm
what are the abnormal functions of pituitary glands i.e. growth hormone production (GA)
overproduction - gigantism
underproduction - dwarfism
what are the 3 types of connective tissue?
Loose - papillary layer of the dermis of the skin
e.g. areolar, adipose
contains permanent and transient cells
Dense regular - in the tendons
Dense irregular - reticular layer of the dermis of the skin
connective tissue comprises cells and extracellular matrix, what 3 things make up ECM?
Fibres (Collagen & Elastin) - rope-like
Ground substance - jelly-like
Tissue fluid - liquid
what 3 fibres make up the extracellular matrix?
collagen - tendons (ordered)
elastin- aorta (wavy)
reticulin - lymph (irregular)
what are elastic fibres?
flexible, can stretch 1.5 times their resting length
made up of microfibrils and amorphous (without a defined form) components.
found in sheets rather than fibres, usually in the Aorta.
describe the characteristics of collagen
30% of body weight
inelastic, flexible, great tensile strength
how is collagen formed?
fibroblasts secrete collagenase and procollagen.
A sum of organised procollagen in a triple-stranded helix shape forms collagen fibrils
A sum of collagen fibrils forms collagen fibres
what are the 3 main types of collagen?
type 1 - tendon
type 3- reticulin (lymphatic organs)
type 4 - basal lamina (non-fibrous)
What is the ground substance that makes up the ECM?
Proteoglycan = (Core Protein + Glycosaminoglycans)
e.g. Hyaluronic acid
Glycoproteins (laminin, fibronectin.. etc.)
what are permanent cells in loose connective tissue? give examples
Permanent cells are cells that develop and remain within the connective tissue
e.g. Fibroblasts, Macrophages, Adipocytes, Mast cells, undifferentiated mesenchyme cells
