Tissues 2 Flashcards
What are glands?
Collection of secretory epithelial cells
How many cells do glands have?
They may be single cells (goblet cells) or multicellular (sweat glands)
What is an example of a single celled gland?
Goblet cells
What is an example of a multicellular gland?
Sweat glands
What are the two types of glands?
Exocrine (secrete into tubes)
Endocrine (secretes into the blood)
What are exocrine glands?
Glands that secrete into tubes
What are endocrine glands?
Glands that secrete into the blood
Why are exocrine glands locally acting whereas endocrine glands can effect distant tissue?
Because exocrine glands release their contents onto a nearby epithelial tissue whereas endocrine glands release their contents into the blood
What are the two forms of duct systems of an exocrine gland?
Simple (unbranched)
Compound (branched)
What are the 2 forms of excreoty components of an exocrine gland?
Tubular
Acinor
What is an example of a simple tubular exocrine gland?
Gastric glands
What is an example of a simple acinar exocrine gland?
Mucus secreting of penile urethra
What is an example of a compound tubular exocrine gland?
Brunner’s gland, empties into intestine
What is an example of a compound acinar exocrine gland?
Pancreas
What is an example of a compound tubuloacinar exocrine gland?
Siliva gland
What are the 3 ways that secretion from an endocrine gland may occur?
Merocrine
Apocrine secretion
Holocrine
What is merocrine secretion?
Involves exocytosis, proteins are usually produced
What is apocrine secretion?
Discharge of vesicles containing secretion, example being sweat gland
What is an example of apocrine secretion from an endocrine gland?
Sweat gland
What is holocrine secretion?
Discharge of whole secretory cells, disintegrate and release product, occurs in sebaceous glands
What is an example of holocrine secretion from an endocrine gland?
Sebacceous gland
How are the secretions often expelled?
From myoepithelial cells and they contract
What are myoepithelial cells?
Cells found in glandular epithelium as a thin layer above the basement membrane but bineath laminal cells
What are endocrines often the source of?
Hormones
What is a hormone?
A chemical messanger
How are most endocrine glands structured?
Clusters of secretory cells surrounded by small blood vessels
Why is the thyroid gland unusual?
It stores its hormones (thyroxine) within spherical cavities called follicles
How does secretion occur within the thyroid gland?
- Reabsorption of hormone from follicle
- Release into intercellular space
- Diffusion into blood stream
What is the secretion of hormones controlled by?
Metabolic factors
What are examples of exocrine organs?
Major silivary glands
Liver