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