Glands Introduction Flashcards
Define a gland
An epithelial cell or aggreate of a cell that are specialised for the secretions of a substance
W what are three features of an endocrine gland ?
1) secrete directly into the blood
2) secrete hormones
3 all epithelial cells secrete hormones from the gland
What is the main endocrine gland called ?
Pituitary gland
Where is the pituitary gland located ?
Beneath the hypothalamus
What are two examples of hormones that the posterior pituitary gland secretes ?
1) oxytocin
2) ADH ( vasopressin)
What are 5 examples of hormones that are secreted by the anterior pituitary gland ?
1) T-SHIRT ( thyroid stimulating hormone )
2) adrenocorticotropin hormone
3) LH
4) follicle stimulating hormone
5) prolactin
Give 5 examples of exocrine glands
1) mammalian gland
2) salivary gland
3) sweat gland
4) sebaceous gland
5) lachymal gland
What is myoepithalial cells ?
- found in glands that are often a mixture of exocrine and endocrine
- they have features of smooth muscle and epithelial cells.
- they help eject secretions from the duct
What type of duct does not exist in an adult ?
- simple alveolar
What are the three modes of secretion ?
- merocrine
- apocrine
- Holocrine
What is merocrine secretion and give an example ?
1) vesicles fuse with the plasmolemma and released through the process of exocytosis.
- an example would be insulin secretion
- this is where ATP increase blocks sensitive k+ channels which causes depolarisation in the beta cell which causes Ca2+ channels open causing ca2+ to enter.
What is apocrine secretion ?
- partial loss of cytoplasm
- only fats are secretes by apocrine glands
- for example mammary glands during lactation period , sweat glands in underarms and genitalia.
- lipid comes. Into contact with apical membrane and pushes against it.
- thin layer of apical membrane surrounds it.
- this membrane then pinches off the cell.
What is holocrine secretion and give an example ?
Complete loss of cytoplasm.
- an example would be the sebaceous gland in the skin and tarsal gland in the eyelid.
- secretarory cells fill up with secretory granules.
- the cell organelles degenerate and cell dies.
- plasma membrane breaks and cell empties contents
Wheat are the three destinations the contents of Golgi apparatus ?
1) vesicles
2) some retained for use inside cells
3) some enters plasma membrane
Pdefine glycosylation
Use of enzymes to covalently attach sugars to lipids and proteins.
What are 4 roles of glycolysation ?
1) prevent protein digestion by protease
2) prevent lipid digestion by lipases
3) aid protein folding
4) aid cell recognition
Define exocytosis
Secretion of molecules outside the cell through vesicles fusing to a membrane
Define endocytosis
Engulfing of molecules inside the cell via vesicle formation
Define phagocytosis
The process by which phagocytes engulf / envelop other cells
Define pinocytosis
- process in which liquid droplets are indigested by cells.
What form of transepithalilal transport do impermeable substances use ? Eg cholesterol
- this is where material is endocytosed at one end of the surface and exocytosed at another end.
What what form of transepithalial transport do amino acids use ?
- they move through the intracellular junction
What form of transepithelilal transport do steroid hormones use ? Eg testosterone , oestrogen , progesterone
Directly through the lipid membrane
How is thyroxine transported across the epithelium?
- via carrier proteins
