Glandular Tissue

Glands

• structures that secrete– either onto the surface of a structure or into a

lumen of an organ via ducts = exocrine• e.g. salivary, lacrimal, sudoriferous

– or directly into the bloodstream (no ducts) = endocrine

• e.g. thyroid, pituitary, adrenals

Exocrine Glands

•exocrine secretions:1. perspiration2. digestive enzymes3. milk4. oil5. mucous

•exocrine gland types:1. serous - watery fluid that contains enzymes

e.g. parotid salivary gland2. mucous - glycoproteins called mucins that absorb water to form a

slippery mucuse.g. minor salivary glands

3. mixed - more than one type of gland cell-produces different types of secretions - mucus and serouse.g. submandibular gland, sublingual gland

Glands of the Skin

• Specialized exocrine glands found in dermis

• Sebaceous (oil) glands

• Sudiferous (sweat) glands

• Ceruminous (wax) glands

• Mammary (milk) glands

Sebaceous (oil) glands• Secretory portion in the dermis

• Most open onto hair shafts

• Sebum– combination of cholesterol, proteins, fats & salts– keeps hair and skin from soft & pliable– inhibits growth of bacteria & fungi(ringworm)

• Acne– bacterial inflammation of glands– secretions stimulated by hormones at puberty

Sebaceous gland

Sudoriferous (sweat) glands• Merocrine/Eccrine (sweat) glands

– most areas of skin– secretory portion in dermis with duct to surface– regulate body temperature with perspiration

• Apocrine (sweat) glands– armpit and pubic region– secretory portion in dermis with duct that opens onto hair follicle– secretions more viscous & stinky!– develop around puberty– Release contents by breaking into pieces

Merocrine

Lacrimal Glands

• secrete tears or lacrimal fluid • forms a “tear film” over the surface of the eye – moistens

& protects the anterior surface of the eyeball• located in the supero-lateral region of the orbit – in the

lacrimal fossa of the frontal bone

Lacrimal Apparatus

• About 1 ml of tears produced per day. Spread over eye by blinking. Contains bactericidal enzyme called lysozyme.

•lacrimal fluid = tears•each gland drains into 6to 12 excretory lacrimal ducts•empties onto the conjuctiva• drains into the lacrimal puncta -> lacrimal canal ->lacrimal sac -> naslacrimal duct -> nasal cavity-innervated by preganglionicparasymp. fibers from the greater petrosal nerve(branch of VII) – synapse with postganglionic fibers of the trigeminal (V) at the pterygopalatine ganglion-blood supply from the lacrimal and opthalmic arteries

Salivary Glands• produce saliva• controlled by the ANS• major and minor glands – defined by size

– parotid– submandibular– sublingual– minor glands:

• Innervated by Facial nerve• buccal, labial and lingual mucosal glands• Found in soft palate, hard palate, floor or mouth• Von Ebner’s glands – associated with the circumvallate

papillae/taste buds (secretion of a serous fluid)• secretion of mainly a mucous saliva containing carbohydrates

Salivary Gland Cellular Structure

• Cells in acini (clusters)• Serous cells secrete a watery fluid• Mucous cells (pale staining) secrete a slimy, mucus

secretion

Parotid Gland

• Parotid below your ear and over the masseter• largest of the major glands• only 25% of total salivary volume – serous fluid• two lobes: superficial and deep• drained by the parotid or Stensen’s duct (superficial to the masseter

and pierces the buccinator)• duct opens into the oral cavity opposite the second maxillary molar

– parotid papilla (figure 7-5)

• occupies the parotid fascial space

• innervated by the parasymp. fibers (motor) of the otic ganglion of Glossopharyngeal Nerve IX + sensory branches of the auriculotemporal branch of trigeminal nerve V

• lymphatic drainage by deep parotid lymph nodes

• blood supply by the external carotid artery branches

Mumps• Myxovirus that attacks the parotid gland

• Symptoms– inflammation and enlargement of the parotid– fever, malaise & sour throat (especially

swallowing sour foods)– swelling on one or both sides

• Sterility rarely possible in males with testicular involvement (only one side involved)

• Vaccine available since 1967

Submandibular Gland

• occupies the submandibular fossa in the submandibular fascial space

• most is superficial to the mylohoid muscle

• provides 60 – 65% of salivary volume• mixed secretion of both serous and mucous• innervated by efferent/motor (parasymp.) fibers of chorda

tympani and submandibular ganglion of the Facial Nerve VII• lymphatics drained by submandibular lymph nodes• blood supply by branches of the facial and lingual arteries• submandibular or Wharton’s duct• duct has a very tortuous path over the anterior floor of the mouth

– often associated with the formation of salivary stones– removal of these stones can damage the lingual branch of V which

is in proximity to the duct

• opens into the oral cavity through the sublingual caruncle– near the midline of the mouth floor on each side of the lingual

frenulum – figure 7-5

Sublingual Gland

• provides on 10% of salivary volume• mix of both serous and mucous secretions

– carbohydrate-rich mucous secretion dominates

• several short ducts that combine to form the sublingual or Bartholin’s duct• major opening into the oral cavity is the sublingual caruncle• other small ducts open via the sublingual fold – a fold of tissue on the lateral

sides of the floor mouth• located in the sublingual fossa in the sublingual fascial space • superior to mylohyoid and anterior to the submandibular gland• innervated by efferent/motor (parasymp) fibers of the chorda tympani and

submandibular ganglion of Facial Nerve VII• lymphatic drainage into submandibular lymph nodes• blood supply by sublingual and submental branches of the lingual artery

Composition and Functions of Saliva

• Wet food for easier swallowing• Dissolves food for tasting• Bicarbonate ions buffer acidic foods

– bulemia---vomiting hurts the enamel on your teeth

• Chemical digestion of starch begins with enzyme (salivary amylase)

• Enzyme (lysozyme) ---helps destroy bacteria• Protects mouth from infection with its rinsing

action---1 to 1 and 1/2qts/day

Salivation

• Increase salivation– sight, smell, sounds, memory of food, tongue

stimulation---rock in mouth– cerebral cortex signals the salivatory nuclei in

brainstem---(CN 7 & 9)– parasympathetic nn. (CN 7 & 9)

• Stop salivation – dry mouth when you are afraid– sympathetic nerves

Thyroid Gland

• comprised of microscopic sacs called follicles = follicular cells making up the walls, surrounds a lumen

• synthesize T3 & T4 (thyroxin)• In between follicular cells cells

are parafollicular cells– produce calcitonin

•On each side of trachea is lobe of thyroid•connected by an isthmus•Weighs 1 oz & has rich blood supply

Actions of Thyroid Hormones

• T3 & T4 = increases metabolic rate

stimulates synthesis of protein

stimulates breakdown of fats (ATP synthesis)

stimulates cholesterol excretion

increases use of glucose & oxygen (ATP production)

increases body temperature (calorigenic effect)