Download glands

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. perspiration
2. digestive enzymes
3. milk
4. oil
5. mucous
•exocrine gland types:
1. serous - watery fluid that contains enzymes
e.g. parotid salivary gland
2. mucous - glycoproteins called mucins that absorb water to form a
slippery mucus
e.g. minor salivary glands
3. mixed - more than one type of gland cell
-produces different types of secretions - mucus and serous
e.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
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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)
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Acne
– bacterial inflammation of glands
– secretions stimulated by hormones at puberty
Sebaceous gland
Sudoriferous (sweat) glands
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Merocrine/Eccrine (sweat) glands
– most areas of skin
– secretory portion in dermis with duct to surface
– regulate body temperature with perspiration
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Apocrine (sweat) glands
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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
•lacrimal fluid = tears
•each gland drains into 6
to 12 excretory lacrimal
ducts
•empties onto the conjuctiva
• drains into the lacrimal
puncta -> lacrimal canal ->
lacrimal sac -> naslacrimal
duct -> nasal cavity
-innervated by preganglionic
parasymp. 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
• About 1 ml of tears produced per day. Spread over eye by blinking. Contains
bactericidal enzyme called lysozyme.
Salivary Glands
• produce saliva
• controlled by the ANS
• major and minor glands – defined by size
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parotid
submandibular
sublingual
minor glands:
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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
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• 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
Parotid below your ear and over the masseter external carotid artery
largest of the major glands
branches
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)
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
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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
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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
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near the midline of the mouth floor on each side of the lingual
frenulum – figure 7-5
• occupies the
submandibular
fossa in the
submandibular
fascial space
• most is superficial to
the mylohoid muscle
Sublingual Gland
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provides on 10% of salivary volume
mix of both serous and mucous secretions
– carbohydrate-rich mucous secretion dominates
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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
•On each side of trachea is lobe of thyroid
•connected by an isthmus
•Weighs 1 oz & has rich blood supply
– produce calcitonin
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)