Glands Flashcards
What are glands?
Epithelial cells that produce secretions
Where do glands develop from?
The ectotherm
What are the 2 types of glands?
Exocrine and endocrine
How are hormones secreted by exocrine glands?
By ducts onto epithelial surfaces
Give 2 examples of exocrine glands.
Sweat and salivary glands
What are the 2 ways exocrine glands are classified?
By structure or method of secretion
What are the 2 structures exocrine glands can be?
Unicellular or multicellular
What are the 2 types of multicellular exocrine structures?
Secretory sheets, or pockets
What are the 3 methods of exocrine gland secretion?
- Merocrine
- Apocrine
- Holocrine
What method of exocrine secretion results in complete destruction of the cell? Give an example of a gland that does this.
Holocrine.
Eg Sebaceous gland
What method of exocrine secretion results in a part of the gland cytoplasm being lost? Give an example of a gland that does this.
Apocrine.
Eg Sweat gland
What method of exocrine secretion results in no damage or loss to the gland?Give an example of a gland that does this.
Merocrine.
Eg Salivary gland
Describe merocrine gland secretion.
Vesicle containing product is released into duct and then secreted
Describe apocrine gland secretion.
Portion of cell where product is stored is pinched off and secreted by duct
Describe holocrine gland secretion.
Plasma membrane ruptures and releases products
How are hormones secreted by endocrine glands?
They are secreted directly into the bloodstream
What can be said about endocrine cell nuclei?
They are prominent
What can be said about endocrine cell mitochondria?
They are abundant
Where are endocrine glands found?
Epithelial surfaces. Thyroid and pituitary gland.
What are 2 functions of endocrine glands?
- Regulating bodily functions
2. Maintaining homeostasis
What are the 2 hormone types produced by the thyroid?
- Iodine-containing hormones
2. Polypeptide hormones
What is thyroxine (T4)? How is converted to it’s active form?
An iodine-containing hormone. Converted to T3 by the removal of one iodothryronine unit
What is the full name for T3?
Tri-iodothryronine
What is the function of T3?
Regulation of metabolic rate and influencing growth
What is Calcitonin?
A peptide hormone
What is calcitonin secreted by?
Parafollicular c-cells
What is the function of calcitonin?
Lowers blood calcium levels by inhibiting osteoclastic resorption of bone.
How many glands does the parathyroid gland have?
4.
One pair on the posterior surface.
One pair on the anterior surface.
What does the parathyroid gland produce that increases blood calcium levels?
Parathyroid hormone
What are the 3 ways parathyroid hormone increases blood calcium levels?
- Stimulates osteoclastic resorption of bone
- Reabsorbs calcium ions from urine
- Increases absorption of calcium from the small intestine
What condition stimulates excessive osteoclastic erosion of bone?
Hyperparathryoidism
What is hypoparathyroidism?
Little to no parathyroid hormone produced. Usually as a result of surgical removal of parathyroid glands.