Exocrine Glands Flashcards
Exocrine glands have 2 portions; the _____ portion & the ______ portion.
Exocrine glands have 2 portions; the secretory portion & the conducting portion.
Describe the secretory portion of exocrine glands
Secretory portion produces secretory product: acinar or tubular.
Describe the conducting portion of exocrine glands
Conducting portion: ducts.
What are the differences between endocrine & exocrine glands?
An Exocrine gland is distinguished by the fact that it excretes its essential product by way of a duct to some environment external to itself, be it either inside the body or on a surface of the body.
Examples of exocrine glands include the sweat glands, salivary glands, mammary glands, and liver.
An Endocrine gland is its counterpart. It secretes its essential product without the use of a duct directly into the bloodstream or else by diffusion into its surrounding tissue (paracrine signaling) where it often affects only target cells near the release site.
Examples of endocrine glands include the adrenal glands, located atop the kidneys and responsible for the secretion of certain hormones such as adrenaline, cortisol and others. The testes, in males and ovaries in females are not only gonads, organs which generate male and female germ cells respectively, but are also endocrine glands in that they produce various androgens and estrogens together known as steroidal sex hormones.
What are the three major mechanisms of secretion? Provide a specific example of a gland for each type.
- Merocrine glands excrete their substances by exocytosis; for example, sweat glands, salivary glands, exocrine pancreas (acinar cells).
- Apocrine glands - a portion of the plasma membrane buds off the cell, containing the excretion. In mammary glands– also called cell “decapitation”: Apical portion pinches off.
- Holocrine glands - the entire cell disintegrates to excrete its substance; for example, sebaceous glands of the skin. This occurs via cell lysis.
What are the differences between simple and compound glands?
Simple glands – single unbranched duct. Secretory portion can be branched or unbranched. Examples: sweat glands and sebaceous glands. Mnemonic = SS.
Compound glands – multiple branched ducts. Secretory portion can be acinar, tubular, or tubuloacinar. Examples: salivary glands and exocrine pancreas.
What is the composition of the sebum?
triglycerides, cholesterol, squalene, wax esters
List cell types found in the sweat glands (pale & dark cells).
Pale cells produce watery component of sweat.
Dark cells secrete glycoproteins and proteins, including bactericidal peptides.
What is the function of myoepithelial cells? Where are these cells located?
Located between basal lamina and secretory or duct cells.
Contraction helps expel secretory product.
Present in sweat, salivary, and mammary glands.
What are the three types of acini found in the salivary glands? How do their secretions differ?
- Serous, mucous, or mixed.
Serous Acinar Cells secrete proteins (amylase, lysozyme, sIgA). Transcytosis = mechanism of sIgA secretion.
Mucous Acinar Cells secrete mucus (heavily glycosilated protein)
Myoepithelial cells.
Saliva composition:
7x K+, 3x HCO3, 1/10 Na+ compared to blood plasma
What is the serous demilune? Are the serous demilunes present in the living tissue?
Serous demilunes (half-moons) are fixation artifacts on some salivary glands in mixed acini so not present in living tissues.
What is the function of basal striations? In which glands and in what part of a gland are the basal striations found?
Basal striations: cell membrane infoldings
that house mitochondria ONLY IN INTRALOBULAR DUCTS. Basal striations are characterized by the basal infoldings of its plasma membrane, characteristic of ion-pumping activity by the numerous mitochondria.
How can you differentiate the pancreas from the parotid gland on the histological preparations?
Endocrine Pancreas: Islets of Langerhans – diagnostic feature of pancreas
What is the content of zymogenic granules?
They are granules found in some secretory exocrine cells. They contain the precursors of enzymes that become active after the granules leave the cell.
Digestive proenzymes including proteases, lipases, nucleases, and amylolytic enzymes.
Pancreatic enzymes are inactive and are activated by enterokinase cleavage in the duodenum. Pancreas also produces protease inhibitors.
Which cells are responsible for producing bicarbonate in the pancreas?
Intercalated ducts
Intralobular ducts & interlobular ducts also secrete bicarbonate-rich fluid.
SEROUS CELL: Secretes ________
SEROUS CELL: Secretes proteins
MUCOUS CELL: Secretes ________
MUCOUS CELL: Secretes mucus
Mucus: heavily glycosylated glycoproteins mucins
Goblet cells: unicellular mucin-secreting unicellular glands in intestinal mucosa & respiratory epithelium
______ junctions seal off the apical surface from the basal surface across epithelium.
Tight junctions seal off the apical surface from the basal surface across epithelium.
Describe the formation of acne
Increased sebaceous gland activity at puberty.
Hair follicle may become plugged.
Skin bacteria (Propionibacterium acnes) break sebum into free fatty acids.
Fatty acids cause irritation and inflammation.
Inflammation attracts neutrophils, further escalating inflammation.
Sweat composition?
Sweat composition**:
Water, Ammonia, Sodium, Chloride,
Urea, Uric Acid, Organic Compounds, Bactericidal Peptides, Proteolytic Enzymes.
Altered sweat composition can be a disease indicator.
Secretion controlled by cholinergic fibers of sympathetic nervous system.
Describe apocrine sweat glands
Located in the axillary, areolar and perineal regions.
Associated with hair shafts.
Simple coiled glands.
The secretory coil is lined by simple cuboidal epithelium and has large lumen.
*Merocrine secretion (despite the gland name).
Secretory product may include pheromones.
Stimulated by adrenergic fibers of the sympathetic nervous system.
List the functions and composition of saliva:
Functions and composition of saliva:
Moisture and lubrication
Initiation of the digestion of carbohydrates: alpha-amylase Immune defense: lysozyme, lactoferrin and IgA
Secretion of calcium and phosphate to make acquired pellicle
Serous, mucous, both, mixed:
1) Submandibular
2) Sublingual
3) Parotid
1) Submandibular: The majority of the acini are serous; mucous and mixed acini are less frequent.
2) Sublingual: Mostly mucous, some serous & mixed.
3) Parotid: serous acini + adipose tissue
