Session 5 Flashcards
(39 cards)
What is the definition of a gland and secretion?
epithelial cell
aggregate of epithelial cells
specialised
secretion of a substance
production
release
material
cell or aggregate of cells
How are glands classified?
structure
release of products method
Describe the endocrine glands
secrete directly into blood flowing through them secrete hormones ductless e.g. pituitary gland anterior and posterior thyroid gland parathyroid gland
all epithelium;ial cells secrete hormones in the gland
Describe exocrine glands
ducted secrete into location or region of the body secrete enzymes or lubricants e.g. salivary gland pancreas mammary sweat glands sebaceous glands lachrymal glands
only cells at the apex of the duct secrete the products
Describe the steps involved in the generation of glands (in utero)
- growth signal received
- proliferation + extracellular degeneration enzymes
- epithelial cells invade
- exocrine gland; canalicularisation
- endocrine glands; angiogenic factors stimulate blood vessel growth
- link to mother cells broken
How does branching occur? (lung example)
basic FGF10 immature fibroblasts epithelial cells move to signal two fates: - tubule elongation - tubule branching
What are the different shapes of gland ducts?
exocrine
cells lining ducts
cells make secretory products
simple tubular, simple branched tubular
compound tubular
simple alveolar, simple branched alveolar
compound alveolar, compound tubuloalveolar
What are myoepithelial cells?
cells at secretory ends change morphology and class
these are cells
have features of epithelial and smooth muscle cell
help eject secretions from duct
Explain the breast example
same process development as salivary glands
developments stops until puberty
oestrogen and progesterone restarts breast production
prolactin stimulates production of breast milk secretions
6th week therefore men too
What three ways can you classify glands?
merocrine - fusion vesicles apical membrane apocrine - partial loss cytoplasm holocrine - complete loss cytoplasm cytocrine - cells released as secretion
What are the two pathways for merocrine secretion?
exocytosis
regulated secretion
needs Ca
secretory granules accumulate large vesicles released by exocytosis
constitutive secretion
secretory product not converted to granules packaged into small vesicles
continuously released to cells surface
repopulate plasma membrane with plasma proteins
Describe the process for regulated secretion in more detail
active process contents of vesicle anything within cell active secretion needs specific signal vesicle migrates to cell surface with Ca ions membrane of vesicle fuses cargo released
Describe the apocrine secretion example of the breast
neonatal period fats secreted milk proteins free ribosomes Golgi apparatus (merocrine)
during lactation
fats and proteins
apocrine
Describe the holocrine secretion example of the sebaceous gland
secretory cell fills up organelles degenerate cells die plasma membrane breaks dead cells replaced
if attached to hair
same process
Describe how the Golgi apparatus is involved in secretion
might need to research
What is glycosylation of proteins/lipids? Describe the functions of it
covalent attachment
sugars
enzymes
forms glycoproteins and glycolipids
roles aid folding prevent protein digestion prevent lipid digestion cell recognition cell to extracellular matrix attachment
critical function
50%
What is exocytosis and endocytosis?
exo
secretion of molecules
outside cell
vesicle fusing to membrane
endo
engulfing molecules
inside cell
vesicle formation
What is phagocytosis and pinocytosis?
phago
cells envelop/ engulf
cells/ particles
cells of immune system
pino
liquid droplets ingested by cell
all cells
Describe the four types of processes of transcytosis
1. molecules move aqueous channels 2. lipid cell membranes 3. molecules appropriate characteristics transported by carrier proteins counter transport process 4. impermeable bind to cell surface receptors endocytosis exocytosis
eg
- amino acids
- steroid hormones
- thyroxine transport
- cholesterol
What are the types of glandular control?
humoral stimulus feedback loops neural stimulus salivary glands hormonal stimulus endocrine glands
Describe the feedback loops for each stimulus
use picture on slide
What is neurocrine communication?
eg hypothalamus to pituitary
hypothalamo- hypophyseal portal system
learn diagram (need to know above system)
What does the hypothalamus deal with and produce?
thermoregulation
plasma osmolality
lactation
etc
vasopressin and oxytocin
six hormones travel via hypothalamo- hypophyseal portal system to anterior pituitary
What are portal systems?
portal vs circulatory
