Salivary glands

Saliva is produced in and secreted from salivary glands.

The basic secretary units of salivary glands are clusters of cells called an Acini.

3 major types of salivary glands are present.

Parotid glands produce a watery secretion

Submaxillary (mandibular) glands produce a mixed watery and mucous secretion

Sublingual glands secrete a saliva that is predominantly mucous in character

Composition

Water Electrolytes:

2-21 mmol/L sodium (lower than blood plasma) 10-36 mmol/L potassium (higher than plasma) 1.2-2.8 mmol/L calcium (similar to plasma) 0.08-0.5 mmol/L magnesium 5-40 mmol/L chloride (lower than plasma) 25 mmol/L bicarbonate (higher than plasma) 1.4-39 mmol/L phosphate

Mucus. Antibacterial compounds (thiocyanate,

hydrogen peroxide, and secretory immunoglobulin A

Various enzymes. There are three major enzymes found in saliva. α-amylase Amylase starts the digestion of starch

and lipase fat before the food is even swallowed. It has a pH optima of 7.4.

lingual lipase. Lingual lipase has a pH optimum ~4.0 so it is not activated until entering the acidic environment of the stomach.

Antimicrobial enzymes that kill bacteria. Lysozyme Salivary lactoperoxidase Lactoferrin[10] Immunoglobulin A[10]

Proline-rich proteins (function in enamel formation, Ca2+-binding, microbe killing and lubrication)[10]

Cells: Possibly as much as 8 million human and 500 million bacterial cells per mL. The presence of bacterial products (small organic acids, amines, and thiols) causes saliva to sometimes exhibit foul odor.

Opiorphin, a newly researched pain-killing substance found in human

Outputs range from 0.75 liters per day to 1.5 liters per day

Secretion of saliva is under control of the autonomic nervous system, which controls both the volume and type of saliva secreted.

Functions

Lubrication and binding: the mucus in saliva binds to food and make it into a slippery bolus that (usually) slides easily through the esophagus without inflicting damage to the mucosa.

Saliva also coats the oral cavity and esophagus, and food basically never directly touches the epithelial cells of those tissues.

Solubilizes dry food: in order to be tasted, the molecules in food must be solubilized.

Oral hygiene: The oral cavity is constantly flushed with saliva, which floats away food debris and keeps the mouth relatively clean. Flow of saliva diminishes considerably during sleep, allow populations of bacteria to build up in the mouth -- the result is dragon breath in the morning.

Saliva also contains lysozyme, an enzyme that lyses many bacteria and prevents overgrowth of oral microbial populations.

Starch digestion: in most species, the serous acinar cells secrete an alpha-amylase which can begin to digest dietary starch into maltose.

Provides alkaline buffering

It is a fluid of the respiratory tract Consist of tracheobronchial

secretions contaminated with: Epithelial cells Nasal secretions Saliva Bacteria

Produced by surface epithelial cells and submucous glands.

Contain mixture of : Plasma Water Electrolytes Mucin

Composition

95% water 5 % solids including: Carbohydrates Proteins ( enzymes, immunoglobulins) Lipids DNA from broken WBC Macrophages Bronchial epithelial cells

Characteristics

Viscoelastic secretion due to the presence of sialic acid .

Normal sputum is colorless and clear Yellow color if puss is present as in

pneumonia Rusty color may be due to decomposed

heamoglobin Red color if there was recent

haemorrhage as in cardiac failure, pulmonary infection, or tuberculousis

Normally its odorless unless there is lung abscesses, gangrene, or tuberculosis.

Odor can change in the presence of bacteria.

Microscopic examination

Bronchial asthma (Allergy): Sputum is white and mucoid NO RBC No pus During infection, Eosinophils and

neutrophils are present in large number

Chronic bronchitis: Increased histocytes and monocytes Increased leucocytes and epithelial

cells Increased LDH activity High DNA level due to cellular

damage

Pneumonia:Can be due to gram- positive or gram-

negativeBacteria:1.Gram – positive: The pathogen is Streptococcus The sputum is less volume and

transparent with some blood flakes Later it becomes rusty red containing

RBC, WBC, and epithelial cells

2. Gram – negative: Pathogens are Enterobacter,

Pseudomonas, Eschercia Coli Sputum is green in color