Exocrine and Specialised Glands Flashcards
Explain how the majority of ductless glands are derivatives of epithelial tissues
- In utero development an epithelial bud is formed and elongates
- Canaliculariation occurs and central cells die to form a duct
Give 3 differences between endocrine and exocrine glands
Endocrine - ductless, secrete hormones into the blood, all epithelial cells secrete the hormone
Exocrine - ducted, secrete enzymes/lubricants via a duct, epithelial cells at duct apex secrete products
Name the two shapes of glands
Simple - unbranched duct with single secretory unit
Compound - branched duct with many secretory units
What are the two arrangements of cells in a secretory unit? Give a description of each
Acinar (‘grapes’) - small ball of cells with a small central lumen
Tubular
Name the 4 duct structures
- Intercalated
- Striated
- Interlobular
- Acini
Name a unicellular gland and where are they found and what is their function?
- Goblet cells
- Secrete mucous in jejunum and colon
Where are the parotid glands and what is their function?
- Bilateral and positioned in front of the ears on the side of the mouth
- Produce saliva with enzymes to begin digestion and lubricate
What type of cell, gland and duct are in the parotid gland and what kind of stimulation is it under?
- Serous acini enclosed in a fibrous capsule
- Serous gland with striated ducts
- Parasympathetic stimulation
Where are the submandibular glands and what do they produce?
- Infront of Parotid under the chin
- In 2 parts, superficial and deep
- Serous and mucous gland
How are the parotid glands stimulated?
- Control of salivary secretion is neural
- Involves parasympathetic and sympathetic stimulation
Briefly describe the blood flow through the liver
- Blood flows from Hepatic Artery through the Hepatic Portal Vein and out through the Central Vein
- Nutrients from stomach and intestine are absorbed followed by release of nutrients and toxins into the Hepatocytes
Is the majority of the blood going to the liver oxygenated or deoxygenated?
Deoxygenated
What links the major vessels of the liver and what is it composed of?
- Sinusoid tube
- Lined with sinusoid cells and hepatocytes
How is the structure of sinusoid cells related to their function?
Sinusoid cells have an incomplete membrane and large intracellular gaps to allow for material exchange with hepatocytes
What shape is a liver lobule?
Hexagonal
Briefly describe the structure of a liver lobule
- Columns of hepatocytes
- Sinusoids between hepatocytes
- Central vein in the middle
- Portal triad of artery, vein and bile ducts at each corner
Name two specialised cells within the liver lobule and describe their function
Kupffer Cell - Move through perforations to phagocytose toxins
Stellate Cell - Full of vacuoles containing Vitamin A
Describe 2 hepatocyte specific characteristics
- 80% epithelial cells
- Both endocrine and exocrine
- Adapted organelles for fast transport
- Apical surface on the side of the cell
Where are hepatocytes located?
Above and below the bile duct
Name the 4 mechanisms of liver signalling
Autocrine - signals target receptors sites on same cell
Paracrine - targets adjacent cells
Endocrine - hormones secreted into blood
Intracrine - hormones stimulate protein production
Name the 3 main categories of liver function
- Storage
- Anabolism (production)
- Catabolism (destruction)
Name 2 substances the liver stores
- Iron
- Lipid soluble vitamins
- Glycogen
- Copper and minerals
Name 2 substances the liver produces
- Albumin
- Enzymes
- Lipid carrier proteins
- Amino acids
Name 2 substances catabolised by the liver
- Drugs
- Hormones
- Haemoglobin
- Poisons/Toxins
Give 1 endocrine and 1 exocrine function of the liver
Endocrine - Hormone synthesis (angiotensinogen, growth factors)
Exocrine - Bile production
What is the location and function of myoepithelial cells in exocrine glands?
- Located near duct opening
- Muscular properties help expel secretions out of the duct
What is the purpose of myoepithelial cells in exocrine glands
Contract to squeeze secretory products into and along the duct
