Flashcards in 2. Glandular Tissues and How Cells Secrete Deck (29)
An epithelial cell or a collection of cells specialised for secretion.
What are the four means of classifying glands?
The destination of secretion, the structure of the gland, the nature of the secretion, the method of discharge.
What is the difference between exocrine and endocrine glands?
Exocrine glands have ducts but endocrine don't, so they secrete straight into the bloodstream.
Is the goblet cell unicellular or multicellular?
Where can goblet cells be found?
In the upper respiratory epithelium.
Give an example of a simple tubular gland.
Give an example of a simple branched tubular gland.
Gastric glands, mucous glands of oesophagus, tongue or duodenum.
Give an example of a simple coiled tubular gland.
Merocrine sweat gland.
Give an example of a simple branched alveolar gland.
Give an example of a simple alveolar/ acinar gland.
Not in adults, in developing simple branched glands.
Give an example of a compound tubular gland.
Mucous glands in mouth, bulbourethral glands in male reproductive system or testes.
Give an example of a compound alveolar gland.
Give an example of a compound tubuloalveolar gland.
Salivary glands, glands of respiratory passages or pancreas.
Describe two difference between mucous and serous glands.
Mucous gland secretions contain mucus and are rich in mucins, but serous secretions are watery and free of mucous.
Serous glands turn pink with H and E stains but mucous glands stain poorly.
Describe the process of apocrine secretion.
Non-membrane bounded structure approaches the cell surface.
It makes contact and pushes up the apical membrane.
A thin layer of apical cytoplasm drapes around the droplet.
The membrane surrounding the droplet pinches off from the cell.
The plasma membrane becomes smaller temporarily but then more is added to return it to the original size.
Describe the process of merocrine secretion.
Membrane bounded component approaches the cell surface.
Membrane fuses with the plasma membrane.
Contents empty into extra cellular space.
The plasma membrane becomes larger temporarily but then returns to normal size as cell surface area is stabilised.
What are the three key stages of holocrine secretion?
Disintegration of the cell.
Release of contents.
Discharge of the whole cell.
Material being engulfed that was originally outside the cell.
What is transepithelial transport?
Endocytosis and exocytosis coupled together.
What happens in transepithelial transport?
Material is endocytosed at one surface, a transport vesicles shuttles it across the cytoplasm and it is exocytosed at the opposite surface.
What is the structure of the Golgi apparatus?
A stack of disc-shaped cisternae with one side of the discs flattened and the other concave. The discs have swellings at the edges which pinch off as migratory Golgi vacuoles.
What is the function of the Golgi apparatus?
Sorting into compartments and packaging by condensation of contents. Glycosylation (adding sugars to proteins and lipids) and transport of resultant vesicles.
Where are the three destinations of vesicles produced by the Golgi apparatus?
Mostly extruded in secretory vesicles. But some are kept in the cells or in the plasma membrane.
What four types of control is secretion under?
Nervous, endocrine, neuro-endocrine and negative feedback chemical mechanism.
What are the names of the three major salivary glands?
Parotid, submandibular and sublingual.
What is the problem with exocrine secretions in CF patients?
There is too little water so the secretions are thickened and ducts become blocked. The exocrine pancreas gets inflamed and fibrotic.
What are some results of insufficient secretion of exocrine enzymes of the pancreas in CF patients?
Faecal excretion of undigested fat (normally as diarrhoea) and malabsorption.
What are the steps in thyroid hormone synthesis?
Synthesis and secretion of thyroglobulin.
Uptake and concentration of iodide from blood, oxidation to iodine and released into colloid.
Iodisation of thyroglobulin in the colloid.
T3 and T4 hormones formed by oxidative coupling reactions.
Resorption of colloid by receptor-mediated endocytosis.
Release of T3 and T4 from cell by exocytosis?