Glands introduction Flashcards
Definition of a gland
An epithelial cell or an aggregate of epithelial cells that are specialised for the secretion of a substance
Defines secretion
The production and release of material by a cell or aggregate ourselves
How a glans classififed
- The structure
2. How their products are released
Define Endocrine
Secrete directly into the blood to act on distal parts of the body. Secretions called hormones
3 examples of Endocrine glands
pituitary
thyroid
parathyroid
What is the anterior pituitary release
ACTH
luteinising hormone
follicle-stimulating hormone
thyroid stimulating hormone
prolactin - stimulates milk production in mothers
somatotrophin - a hormone which regulates the growth of the body and tissue
What does the posterior pituitary release
Antidiuretic hormone - prevents water loss from kidneys
oxytocin - signal uterus for delivery of baby
Thyroid glands release
T3 active and T4 inactive
Parathyroid gland release
Parathyroid hormone, calcium homeostasis
What epithelial cells of a Endocrine tissue secrete substance
All epithelial cells secrete the hormones in the gland
Define exocrine
Glands secrete into a location or region of the body through a duct and the secretion is mostly enzymes or lubricants
Give six examples of endocrine glands
Salivary gland pancreas mammary sweat gland sebaceous glands lachrymal glands
Salivary gland
Secrete saliva, function includes partial digestion of food and lubrication
Pancreas
enzymes: amylase trypsin and lipase these enzymes digest carbohydrates proteins and fats respectivly
Mammary glands
Produce milk in response to prolactin and oxytocin
Sweat glands
Screech sweat which regulates body temperature
Sebaceous glands
Secrete sebum onto the skin of the ear protectors you from pathogen
Lachymal glands
In I secretes water to moisten the eye also produces lysosomes
In exocrine glands what cell releases product
Only apex of ducted secretes product
In exocrine glands what cell releases product
Only apex of duct secretes product
In lungs branch and occurs by growth factor 1 and 2 explain how we get trivial elongation or tubule branching
Elongation factor one active growth and two in active
branching growth up to one in active growth factor to active
Some cells are end of ducks change morphology explain this
Myoepithelial cells - cells that have features of both epithelial cells and smooth muscle cells - helps injecting secretions from the duct
Three types of secretions
Merocrine
apocrine
holocrine
merocrine
vesicles fuse with membrane cargo released outside by exocytosis. Two pathways regulated and constitutive
apocrine
Partial loss of cytoplasm. vesicles bundle at top of cell whole top of cell is released
holocrine
Complete loss of cytoplasm also
How is secretion controlled
Negative feedback
nervous
endocrine
neuroendocrine
Explain merocrine regulated and constitutive regulation
Regulated: secretory granules accumulate in large be schools and are released by exocytosis upon stimulation, need calcium ions
constititive: the secretory product is not concentrated into granules but packaged into small the schools and continues to be released to he cell surface - use may need to repopulate the plasma membranes
Merocrine pathway release of insulin from beta cells of the pancreas
Glucose moves into cell viaGLUT2
potassium channels open allowing potassium to leave cell
this Depolarises the cell
causes voltage-gated calcium channels to open
calcium used in these confusion causes insulin released outside cell
Give an example of an Apocrine secretion
Breast - both fat and milk realised this way
holocrine example
Sebaceous gland
the secretory cell fills up with secretory granules
cells organelles die
the cells die
the plasma membrane breaks and the contents released
dead cells are replaced by mitotic division in the basal cells
Role of Golgi apparatus
Secretion of proteins
glycosylation of proteins
Where does Golgi apparatus glycosylation occur
Trans-Golgi
Why glycosylated proteins
Aid folding
prevent digestion
cell ecognition e.g. blood groups
roll on cell to extracellular matrix attachment
Exocytosis vs endocytosis
Exocytosis
secretion of molecules outside the cell by vesicle fussing to a membrane
Endocytosis
engulfing of molecules inside the via vesicle formation
Two types of endocytosis
Phagocytosis- engulf other cells
Pinocytosis- cell drinking
Trans-epithelial transport
Passive diffusion
through Lipid membrane
transported by carrier proteins
or impermeable proteins could be transported by Endo and exocytosis
Control gland secretions
Hormonal, neural, humoral
neural
Release of hormones in response to nerval stimulus
humoral
Control of hormone release in response to changes in the extracellular fluid levels or ion levels
neurocrine
Example the hypothalamus to the pituitary
