Salivary Glands Quiz

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Questions and Answers

What percentage of saliva is secreted by minor salivary glands?

15%

20%

10% (correct)

Which type of secretion is NOT produced by salivary glands?

Seromucous

Serous

Mucous

Sanguineous (correct)

What is the primary anatomical characteristic of minor salivary glands?

Medium-sized and partially encapsulated

Small and non-capsulated (correct)

Large and encapsulated

Non-existent in humans

Which type of salivary secretion would contain enzymes for digestion?

Serous Signup and view all the answers

What is the function of salivary glands in the oral cavity?

Producing saliva for lubrication and digestion Signup and view all the answers

What percentage of saliva is produced by the major salivary glands?

90% Signup and view all the answers

Which of the following salivary glands is NOT classified as a major gland?

Buccal gland Signup and view all the answers

Which gland is the largest among the major salivary glands?

Parotid gland Signup and view all the answers

How much saliva do the major salivary glands produce daily on average?

0.75 to 1.50 L Signup and view all the answers

What is the primary function of salivary glands?

Producing saliva Signup and view all the answers

What percentage of total saliva is produced by the largest salivary glands?

65% Signup and view all the answers

What type of cells predominantly make up the secretory portions of the largest salivary glands?

Mainly serous cells Signup and view all the answers

What are the serous demilunes found in the largest salivary glands?

Mucous cells capped with serous cells Signup and view all the answers

Which of the following statements accurately describes the types of secretions from the largest salivary glands?

Both mucous and serous secretions Signup and view all the answers

Which function is primarily associated with the secretory cells in salivary glands?

Digestive enzyme secretion Signup and view all the answers

Study Notes

Salivary Glands

Salivary glands are exocrine glands located in the mouth
Divided into major and minor glands
Major salivary glands produce 90% of saliva
Large, encapsulated glands
Produce 0.75 to 1.50 L of saliva daily
Three types of major salivary glands: parotid, submandibular, and sublingual

Types of Secretions

Salivary glands secrete serous, seromucous, or mucous secretions

Minor Salivary Glands

Small, non-encapsulated glands
Secrete 10% of saliva
Primarily mucous except for Von Ebner glands

Functions of Salivary Glands

Protection: Lubricates and moisturizes the mouth, creating smoother speech, and forms a protective film on teeth
Digestion: Converts starch to maltose with salivary amylase, and helps chewing and swallowing
Antimicrobial: Lysozyme, peroxidase, and lactoferrin fight pathogens
Tissue Repair: Accelerates blood clotting for faster tissue repair in the mouth

Medical Applications

Dry Mouth (Xerostomia): Insufficient saliva secretion, caused by disease, infections, dehydration, or drugs
Excessive Saliva Production (Sialorrhea): Caused by oral cavity inflammation (sialadenitits) or viral infection

Structure of Major Salivary Glands

A stroma (capsule of connective tissue)
Lobules separated by septa (connective tissue)
Lobules composed of acini (secretory units) and ducts
Secretory unit is composed of cells
Ducts are composed of cells connected to acini

Two Major kinds of Secretory Unit Cells: Serous Cells and Mucous Cells

Serous Cells: Pyramidal in shape with broad base & narrow apical surface; round nucleus; well-stained RER (rough endoplasmic reticulum); basophilic cytoplasm; junctional complexes; cells forming an acinus (rounded secretory unit); apical zymogen granules
Mucous Cells: More columnar in shape; flat basal nuclei; apical granules with hydrophilic mucins (cause poor cell staining); wider lumen; organized as cylindrical tubules, rather than acini; produce mucins for lubrication & protection

Submandibular Gland (Mixed Gland)

Branched tubuloacinar gland
Largest salivary glands, producing 65% of total saliva
Secretory portions contain both serous and mucous cells
Serous demilunes (cap of serous cells) are present on mucous cells
Infoldings of the serous cells' membrane increase ion-transporting surface area
Synthesize amylase (starch digestion), proline-rich proteins, and lysozyme

Sublingual Gland (Mixed Gland)

Smallest major salivary gland
Branched tubuloacinar gland
Formed of serous and mainly mucous cells
Producing only 5% of saliva
Serous cells are in demilunes on the mucous tubules
Products mainly mucus
Secrete amylase and lysozyme

Myoepithelial Cells

Found inside the basal lamina of the secretory units
Well-developed and branched, sometimes called basket cells
Spindle-shaped, lie parallel to the duct's length
Their contraction accelerates product secretion

Intralobular Duct System

Intercalated Ducts: Smallest branches, lined by small cuboidal epithelial cells with a nucleus in the center, some secretory granules, and few microvilli; Myoepithelial cells are present
Striated Ducts: Lined by columnar cells, specialized for ion transport; pink striations in the basal half; striations are folds in the plasma membrane with mitochondria
Excretory Duct: Increasing size and thicker connective tissue, unusual combination of epithelial types; initially (lined with pseudostratified or stratified cuboidal epithelium); more distal parts lined by stratified columnar epithelium; reflects diverse functions: cells for ion reabsorption, cells for secretion of mucin and proteins

Main Excretory Ducts of Salivary Glands

Stensen's duct (parotid gland)
Wharton's duct (submandibular gland)
Bartholin's duct (sublingual gland)

Parotid Gland

Located in each cheek near the ear
Branched acinar gland
Cells are purely serous with very small lumens
Produces 20% of total saliva
Secrete amylase for carbohydrate hydrolysis
Proline-rich proteins have antimicrobial properties

Pancreas

Located behind the stomach in the upper left abdomen
Spongy, pear-shaped
25 cm long, 5 cm wide, 1-2 cm thick, weighing approximately 150 g
Main parts: head, body, tail
Main pancreatic duct (duct of Wirsung), runs the length of the pancreas and joins the bile duct
Pancreatic islets (Islets of Langerhans): Endocrine tissue producing hormones like insulin and glucagon, regulating blood sugar and carbohydrate metabolism
Acinar cells: exocrine, secrete digestive enzymes

Pancreatic Digestive Enzymes

Proteases (Trypsin and chymotrypsin): Break down proteins; help keep the intestine free of parasites
Amylase: Breaks down carbohydrates (starch) into sugars easily absorbed by the body (also found in saliva)
Lipase: Breaks down fat molecules for easy absorption
Enzymes produced as inactive molecules (zymogens), preventing self-digestion in the pancreas, and become active in the duodenum

Histological Structure of Pancreas

Stroma: Contains capsule of connective tissue and septa separating pancreatic lobules
Parenchyma: Includes pancreatic lobules, pancreatic islets (Islets of Langerhans), pancreatic acini, pancreatic ducts, and capillary network

Pancreatic Acinar Cells

Consists of serous cells
Small lumen
Without myoepithelial cells
Typical protein-secreting cells
Nucleus in the basal third of the cell
Well-developed RER, Golgi, and basophilic cytoplasm
Presence of zymogen granules (contains proenzymes, inactive precursors of enzymes)

Pancreas Duct System: Intercalated Ducts

Connected with acini
Lined by simple squamous epithelium
Penetrate acini lumens, forming larger centroacinar cells
Secrete a large volume of fluid rich in bicarbonate ions, alkalizing and transporting enzymes from acini

Pancreas Duct System: Intralobular Ducts

Resembles intercalated duct of salivary glands
Lined with simple cuboidal epithelium

Pancreas Duct System: Interlobular Ducts

Lined with simple columnar epithelium
Main pancreatic duct (duct of Wirsung) branches to accessory pancreatic duct (duct of Santorini), which joins the common bile duct before opening into the duodenum at the ampulla of Vater; secretions regulated by a muscular valve (sphincter of Oddi)

Liver

Second-largest organ in the body
Largest gland
Located in the abdominal cavity, beneath the diaphragm, protected by ribs
Weighs about 1-1.5 kg (2% of adult's body weight)
Over 500 functions

Anatomical Structure

Large right lobe
Smaller left lobe
Two smaller inferior lobes: quadrate and caudate lobes
Over 500 functions

Liver Histological Structure

Stroma: Capsule and septa separating the liver into lobules
Parenchyma: Hepatic lobules, composed of hepatocytes (liver cells), reticular fiber network, surrounds & supports liver cells and sinusoidal endothelial cells

Liver: Hepatic Lobules

Basic functional unit of the liver
Polyhedral, hexagonal shape
Composed of hepatocytes (liver cells) arranged as plates radially around the central vein
Liver sinusoids (leaky capillaries) between hepatic plates

Portal Triads at each Corner of the Lobules

Branch of portal vein
Branch of hepatic artery
Branch of bile duct

Hepatocytes

Large polygonal epithelial cells
Able to regenerate (5 months)
Arranged as plates radially around the central vein
Binucleated
50% are polyploid
Eosinophilic cytoplasm due to numerous mitochondria
Basophilic due to rich RER for protein synthesis
Rich in SER for bile salts, detoxification, and clearance substances before excretion
Microvilli in perisinusoidal space
Contain up to 50 Golgi complexes for protein, glycoprotein, and lipoprotein secretion into plasma

Hepatic Sinusoids

Spaces between hepatic plates lined with fenestrated endothelial cells
Perisinusoidal space (Space of Disse): Between hepatocytes and sinusoidal endothelial cells where nutrient-rich blood from portal vein (low O2) and oxygen-rich blood from hepatic artery mixes, allowing fluid and plasma components to be absorbed by hepatocytes

Functions of the Liver

Bile production: Exocrine function, bile helps fat digestion
Protein synthesis: Synthesizes albumin, fibrinogen, cholesterol, phospholipids, and other proteins
Detoxification: Neutralizes toxic substances
Storage of vitamins and minerals
Phagocytosis of dead red blood cells (Kupffer cells)
Iron and glucose storage
Lipid metabolism and Gluconeogenesis: Converted lipids and amino acids into glucose

Cells Associated with Sinusoids

Endothelial Cells: Line sinusoids, are fenestrated for protein and plasma component transport
Kupffer Cells: Stellate macrophages, phagocytic cells that clean the blood; break down aged erythrocytes into globin and heme; removing bacteria; antigen-presenting cells
Stellate Cells (Ito Cells): Lipocytes, responsible for storing vitamin A; mesenchymal cells producing extracellular matrix components of liver cells and producing cytokines regulating Kupffer cell activity

Bilirubin Metabolism in the Liver

Bilirubin is a byproduct of heme breakdown
In the liver, bilirubin is transformed into a water-soluble form by enzymes, allowing for its excretion in the bile

Liver Regeneration

Compensatory hyperplasia: Increased cell numbers in healthy hepatocytes through mitosis to maintain the original tissue mass
Stem cells: Oval cells in the epithelium of Hering's ducts differentiate into hepatocytes or cholangiocytes, contributing to new cell formation

Jaundice

Yellowing of the skin and whites of eyes due to excess bilirubin in the blood
Can result from gallstones, liver infections, or anemia; undeveloped SER in newborns (neonatal hyperbilirubinemia); Tx involves exposing to blue light therapy to transform bilirubin into a water-soluble form.

Cholelithiasis (Gallstones)

Presence of gallstones in the gallbladder or bile ducts (cholesterol or bilirubin concentration)
Causes: Genetics, body weight, decreased motility in the gallbladder, diet; removal of the gallbladder due to obstruction or chronic inflammation will cause a direct flow of bile from liver to duodenum with minimal digestion problems.

Bile Duct System

Bile canaliculi: Formed on apical surfaces of hepatocytes, creating canals between neighboring hepatocytes, and are the primary site of bile secretion, with junctional complexes connecting hepatocytes, and containing microvilli
Bile Canals of Herring: Receive bile canaliculi from numerous hepatocytes and continue into the larger bile ducts
Bile Ducts (Ductules): Lined by columnar epithelium. In the portal spaces; form right and left hepatic ducts that exit the liver

Gallbladder

Hollow, saclike organ on the lower liver surface
Stores 30-50ml of bile
Lined with simple columnar epithelium with no goblet cells
Contains lamina propria rich with elastic fibers and blood vessels (no muscularis mucosa, no submucosa)
Muscle layer (muscularis externa): Thin, bundles of circular muscles; connective tissue layer (adventitia, serosa)
Functions: Stores and concentrates bile by absorbing water, released into duodenum when necessary by active sodium-transporting action. Causes contraction to move the stored bile into duodenum due to cholecystokinin (CCK)

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Description

Test your knowledge on the anatomy and function of salivary glands. This quiz covers the characteristics, types of secretions, and the percentage of saliva produced by minor and major salivary glands. Ideal for students studying human anatomy or oral biology.