Glandular Tissue

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Glandular Tissue
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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

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Exocrine Glands

• exocrine secretions
• 1. perspiration
• 2. digestive enzymes
• 3. milk

• exocrine gland types
• 1. serous - watery fluid that contains enzymes
• e.g. saliva
• 2. mucous - glycoproteins called mucins that
  absorb water to form a
• slippery mucus
• 3. mixed - more than one type of gland cell
• -produces different types of secretions - mucus
  and serous
• e.g. submandibular gland

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Glands of the Skin

• Specialized exocrine glands found in dermis
• Sebaceous (oil) glands
• Sudiferous (sweat) glands
• Ceruminous (wax) glands
• Mammary (milk) glands

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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

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Sudoriferous (sweat) glands

• 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

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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

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• lacrimal fluid tears
• each gland drains into 6
• to 12 excretory lacrimal ducts
• empties onto the conjuctiva
• drains into the lacrimal
• puncta -gt lacrimal canal -gt
• lacrimal sac -gt naslacrimal
• duct -gt 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

Lacrimal Apparatus

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

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Salivary Glands

• produce saliva
• controlled by the ANS
• major and minor glands defined by size
• parotid
• submandibular
• sublingual
• minor glands
• Facial nerve
• buccal, labial and lingual mucosal glands
• soft palate, hard palate, floor or mouth
• Ebners glands associated with the
  circumvallate papillae/taste buds (secretion of a
  serous fluid)
• secretion of mainly a mucous saliva containing
  carbohydrates

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Salivary Gland Cellular Structure

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

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Parotid Gland

• occupies the parotid fascial space
• innervated by the parasymp. fibers of the otic
  ganglion of IX sensory branches of the
  auriculotemporal branch of V
• lymphatic drainage by deep parotid lymph nodes
• blood supply by the external carotid artery
  branches

• 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 Stensens 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)

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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

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Submandibular Gland

• provides 60 65 of salivary volume
• mixed secretion of both serous and mucous
• innervated by efferent (parasymp) fibers of
  chorda tympani and submandibular ganglion of VII
• lymphatics drained by submandibular lymph nodes
• blood supply by branches of the facial and
  lingual arteries
• submandibular or Whartons 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

• occupies the submandibular fossa in the
  submandibular fascial space
• most is superficial to the mylohoid muscle

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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 Bartholins 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 (parasymp) fibers of the
  chorda tympani and submandibular ganglion of VII
• lymphatic drainage into submandibular lymph nodes
• blood supply by sublingual and submental branches

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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

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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

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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

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Actions of Thyroid Hormones

• T3 T4 increases metabolic rate
• stimulates synthesis of protein
• stimulates breakdown of fats
• stimulates cholesterol excretion
• stimulates synthesis of proteins
• increases use of glucose oxygen
• (ATP production)
• increases body temperature (calorigenic effect)

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Control of T3 T4 Secretion

• Low blood levels of hormones stimulate
  hypothalamus -gt TRH
• It stimulates pituitary to release TSH
• TSH stimulates gland to raise blood levels
• T3 and T4 regulate themselves through a negative
  feedback loop

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Parathyroid Glands

• Principal cells produce parathyroid hormone (PTH)
• Oxyphil cell function is unknown

• 4 pea-sized glands found on back of thyroid gland

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Parathyroid Hormone

• Raises blood calcium levels
• increases activity of osteoclasts
• increases reabsorption of Ca2 by kidney
• promote formation of calcitriol (vitamin D3) by
  kidney which increases absorption of Ca2 and
  Mg2 by intestinal tract
• Opposite function of calcitonin (thyroid)

• High or low blood levels of Ca2 stimulate the
  release of different hormones --- PTH or CT
• high level of calcium in blood - release of
  calcitonin by parafollicular cells, promotes
  uptake of calcium into bone matrix, lowers blood
  calcium
• low level of calcium in blood - release of PTH by
  parathyroid glands, promotes release of calcium
  from bone, raises blood calcium

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Thymus Gland

• Important role in maturation of T cells
• Hormones produced by gland promote the
  proliferation maturation of T cells
• thymosin
• thymic humoral factor
• thymic factor
• thymopoietin