Anatomy and Cell Biology 3309 finals.docx

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Anatomy and Cell Biology
Anatomy and Cell Biology 3309
Graeme Taylor

Finals: Lecture 3 and 4: Respiratory System Objectives: Functions: • ƒ Air conduction • ƒ Air filtration • ƒ Gas exchange • ƒ Also endocrine role – hormone production and secretion • ƒ Also immunological role Epithelium of respiratory system – endodermal origin Origin of supporting structures – mesenchyme (from mesoderm) 1. List the structures and describe the path of air through the conducting and respiratory passages of the lung Respiratory system divided on to 2 portions: 1. Conducting portion • ƒ Nasal cavities • ƒ Nasopharynx and oropharynx • ƒ Larynx • ƒ Trachea • ƒ Bronchi • ƒ Terminal bronchioles 2. Respiratory Portion (gas exchange) • ƒ Respiratory bronchioles • ƒ Alveolar ducts • ƒ Alveolar sacs • ƒ Alveoli Nasal cavity • ƒ Lined by respiratory epithelium • ƒ Areas covered by olfactory epithelium – responsible of sense of smell Olfactory epithelium (pseudostratified) consists of the following cell types: o Olfactory cells – bipolar neurons –axon leaves epithelium and joins with others to form olfactory nerve Apical surface contains olfactory vesicle and non-motile cilia o Supporting cells – microvilli, provide mechanical and metabolic support to olfactory cells o Basal cells – stem cells * renewal for All cell types including olfactory cells (correction from lecture) o Brush cells – apical surface contains blunt microvilli (not cilia!). Basal surface synapses with nerve fibres – responsible for general sensation not olfaction Olfactory glands (Bowman’s Glands) found in lamina propria (connective tissue below epithelium). Serous glands which release secretion on surface of olfactory mucosa – odiferous substances become trapped and dissolve in secretion – allows detection by olfactory receptors. Pharynx - Covered by stratified squamous epithelium - mucosa contains diffuse lymphatic tissue and nodules Larynx – in front of esophagus • ƒ- Partially covered by stratified squamous epithelium, transition to respiratory epithelium • ƒ - Mucosa contains lymphatic tissue and nodules as well as seromucous glands. Trachea • ƒTube about 10-12 cm long and 2 cm in diameter • ƒ Wall is reinforced by 10 -12 horseshoe cartilage rings (open ends face posteriorly) • ƒRings are connected by fibroelastic connective tissue – imparts flexibility and elongation during inspiration • ƒ Smooth muscle (trachealis muscle) joins ends of cartilage rings – contraction narrows lumen of trachea (cough reflex) • ƒ Trachea serves to conduct air into the lungs and also to condition the inspired air Tracheal wall: Mucosa o Epithelium consists of pseudostratified ciliated columnar cells with goblet cells resting on a thick basement membrane • Goblet cells – 30% of population, produce mucinogen • Ciliated columnar cells – 30% of population basally located nucleus, cilia and microvilli on apical surface, move mucus and particulate matter towards nasopharynx for elimination • Basal cells – 30% of cell population, stem cells • Brush cells – 3% of population, blunt microvilli (not cilia!) which project into the lumen, basal surface in contact with afferent nerve ending – receptor cells • Granule cells or enteroendocrine cells – few and difficult to distinguish from basal cells -– secrete catecholamines, serotonin, calcitonin – functions not well understood o Lamina propria and thick bundles of elastic fibres ƒ Submucosa o Dense irregular fibroelastic connective tissue o High blood supply – warms air o Mucous and seromucous glands – humidify air o Lymphoid tissue and high lymph supply Cartilaginous layer o C shaped hyaline cartilage rings Adventitia o Fibrous connective tissue which anchors trachea to neighbouring structures (esophagus and connective tissue of the neck) 2. Distinguish between bronchi and bronchioles. 3. Describe the changes in the epithelium throughout the air passageways Bronchi Trachea bifurcates into 2 primary bronchi that enter lungs at hilum (extrapulmonary bronchi). Each primary bronchi further divide into 3 lobular (right lung) and 2 lobular (left lung) bronchi (intrapulmonary bronchi) – each supplies a pulmonary lobe Bronchi wall Mucosa o Same as trachea except as luminal diameter decreases, cells transition from columnar to cuboidal, basement membrane also decreases in thickness o Lamina propria – similar to trachea but reduced in thickness o Muscularis – continuous layer of smooth muscle – decreases and becomes discontinuous in smaller bronchi Submucosa o Loose connective tissue with glands and adipose tissue present Cartilaginous layer o hyaline cartilage plates become smaller as diameter decreases Adventitia o Dense connective tissue which is continuous with adjacent structures Bronchioles Less than 1 mm in diameter, no cartilage, no glands, prominent layer of smooth muscle associated with elastic fibres, no goblet cells in terminal bronchioles (smallest unit of conducting portion) ƒ Mucosa o Initially ciliated pseudostratified columnar epithelium which transitions to simple ciliated cuboidal epithelium in terminal bronchiole o Cuboidal cells interspersed with Clara cells – non ciliated cells with dome shaped apical surface – secrete surfactant- like protein to reduce surface tension o No goblet cells in terminal bronchioles Respiratory Bronchioles • Subdivision of terminal bronchiole • First part of bronchial tree which allows gas exchange • Alveoli and alveolar ducts branch from respiratory bronchioles • Initially, both cuboidal and Clara cells, eventually, Clara cells predominate Alveolar Ducts • Thin tube with several branches • Discontinuous walls • Many alveoli • Some cuboidal epithelium and smooth muscle • Type III collagen fibers around opening of alveoli 4. Describe the histological organization of the alveolar-capillary barrier. Alveoli • 200 um in diameter, total surface area = 140 m2 • Alveolar wall – surface epithelium, supporting tissue, blood vessels, interalveolar septum is rich in type II collagen Epithelium o Type I pneumocytes - serve as extremely thin gaseous diffusion barrier o Type II pneumocytes – 60% of cells in epithelium • ƒ Rounded shape secretes surfactant (reduces surface tension to prevent lung collapse during expiration) • ƒ Central nuclei, lots of rER, Golgi and mitochondria • ƒ Can divide and differentiate into Type I pneumocyte o Supporting tissue • ƒ Reticular, collagenous and elastic fibers • ƒ Occasional fibroblast and alveolar macrophage (dust cells) o Blood vessels ƒ Mainly capillaries that form a plexus around each alveolus • Air-blood barrier o Gas must diffuse across this barrier o Consists of : surfactant, type I pneumocyte and its basement membrane, capillary endothelial cell basement membrane, capillary endothelial cell 5. Outline the importance of elastin in the respiratory system. 6. Explain the functional significance of the secretory cells found in all areas of the respiratory system. Lecture 5 - Teeth: 32 permanent teeth; 8 in each quadrant; 2 incisors, 1 canine, 2 premolars, 3 molars - Permanent teeth are preceded by 20 deciduous (baby) teeth - there are no deciduos precursors of the 12 permanent molar teeth (all the molars) Structure of the tooth: crown - Portion of tooth that projects above the gingival/gum - Crown is covered by enamel Roots - one or more roots lie below the gingival and hold the teeth in bony sockets (alveoli) neck - enamel and cementum meet at the neck (or cervix) Pulp cavity - a tissue filled space surrounded by a calcified material called dentin and extends to the root canal (apex of the root) Apical - an orifice that permits entrance and exit of the blood vessels, lumphatics and foramen nerves of the pulp cavity Periodonta - a collagenous , fibrous structure inserted in the cementum that serves to fix the l ligament tooth firmly in its bony socket Dentin: - a calcified tissue similar to bone byt harder due to a higher content of calcium salts - composed mainly of Type 1 collagen, GAGs and calcium salts (70% of weight) - calcium salts are in the form of crystals of hydroxyapatite - the organic matrix of dentin is secred by odontoblasts Odontoblasts - line the internal surface of the tooth, separating it from the pulp cavity - possess branched cytroplasmic extenstions, the odontoblast processes (Tomes fibres – run through the small canals called dentinal tubules) - these processes penetrate perpendicularly through the width of the dentin - the gradually become longer as the dentin becomes thicker - the tubules are extensively branched near the junction b/w the dentin and enamel - the matrix produced by odontoblasts is initially unmineralized and is called predentin - mineralization begins when matrix vesicles appear - matrix vesicles contain fine hydroxyapatite crystals - crystals grow and serve as nucleation sites for further mineral deposition on surrounding collagen Enamel: - the hardest component of the human body and the richest in calcium - consists of 95% calcium salts (mainly hydroxyapaetite), 0.5% organic material + water - the organic material is composied of amelogenins and enamelins - enamel consists of elongated rods or columns of hydroxyapetite crystals called enamel rods - each rod (keyhole shaped) extends through the entire thickness of the enamel layers - the enamel matrix is secreted by cells called ameloblasts - ameloblasts are tall columnar cells with an apical extension called the Tomes’ process - Tomes process contains secretory granules filled with the proteins of the enamel matrix Pulp - LCT – contains odontoblasts, fibroblasts, fibres, and matrix - highly innervated and vascularised - blood vessels and nerve fibres enter the apical foramen and branch extensively - some pain conducting nerves lose their myelin and extend into the dentinal tubules Cementum: - covers the dnetin of the root - similar in composition to bone – no Haversian system or blood vessels present - cells called cementocytes – similar to osteocytes - lacunae and canaliculi are present - cementum undergoes resorption and remodelling like bone Periodontal Ligament: - composed of DCT with fibres that penetrate the cementum - serves as periosteum of the alveolar bone - binds the tooth to the bony socket - fibres are organized to accommodate pressures created during mastication - there is a high rate of collagen turnover which allows orthodontic intervention Alveolar Bone: - alveolar bone is an immediate contact with the periodontal ligament - consists of immature bone without the lamellar arrangement typical of mature bone - alveolar bone and cementum penetrated by fibres of the periodontal ligament – which bridge the two Development of the tooth: - @ 6 weeks gestation, the basal layer of the oral epithelium (ectoderm) proliferates - it buldges into the underlying mesenchyme to form a dental lamina in each jaw - regions of mitotic activity occur in each dental lamina – forming tooth buds/ one per tooth - the ectoderm component ƒ enamel organ - the underlying mesenchyme ƒ dental papilla (includes orthoblasts) - mesenchyme around enamel organ ƒ cementoblasts and periodontal ligament - @ 8 weeks gestation: the enamel organ becomes bell shaped - outer enamel epithelium is indented by numerous capillaries - columnar cells next to dental papilla from inner enamel epithelium – becomes ameloblasts - odontoblasts secrete predentin which stimulates the secretion of enamel by ameloblasts Formation of Dentin: - odontoblasts secrete procollagen ƒ collagen fibres of predentin - odontoblasts also mediate mineralization of collagen fibres to produce dentin - cell bodies of odontoblasts move toward puplp caivity as dentin is laid down - odontoblastic processes become surrounded by dentin to form dentinal tubules - tubules span the thickness of the dentin Formation of Enamel: - enamel matrix is secreted by short extensions of ameloblasts called Tomes’ processes - Tomes’ processes produce organic matrix of both interrod enamel and enamel rods - enamel organ is rapidly eroded when the tooth erupts @ 6 weeks gestation @ 8 weeks gestation 1. Bud Stage 2. Early cap 3. Late cap stage 4. Bell 5. Tooth eruption stage Stage Mitotic activity of Oral epithelium Enamel organ; Outer dental - produce - enamel epithelial cells = of tooth budƒ epithelial lining interrod organ tooth bud/ tooth Inner dental Pre-ameloblasts Secrete enamel rapidly epithelial lining ƒ ameloblasts enamel and eroded via enamel Tomes’ rods processe s Neuroectodermal Underlying Cytokines push Dental papilla; Pre- orthoblasts Secrete cells in mesenchyme ƒ mesenchyme up - cranial neural crest/ƒ orthoblasts dentin mesenchyme to help form neuroectoderm ƒ via induce epithelial enamel organ Tomes’ cells to proliferate fibres in and invaginate dentinal canals -(inner) cementoblasts Mesenchyme around enamel organ  dental sac ƒ secrete cementum - (outer) periodontal ligament Lecture 7– GI Tract: General Plan: Esophagus Stomach Description: - straight tube, conveys food (Pharynx ƒ - functions as a reservoir and a digestive organ, limited stomach) absorption - numerous longitudinal folds in lumen - rugae – folds in mucosa - gastric pits – invaginations of surface 1. Mucosa a. Epithelium; protective/ absorptive- Stratified, squamous, non-kerat., “wear and - columnar “surface epithelial cells”; no goblet cells secretory tear” - mucous @ apical portion b. Lamina propria; LCT w/ lymphocytes LCT w/ lymphocytes, papillae, cardiac - filled with gastric glands glands - delicate fibres and usual LCT cells + lymphocytes c. Muscularis Muscosae – thin layer of sm. Longitudinal smooth muscle - 2 to 3 layers of smooth muscle Muscle 2. Submucosa a. LCT w/ elastic fibres DCT w/ lymphocytes and esophageal glands DCT w/ blood and lymph vessels b. blood vessels + nerves + Meissner’s plexus 3. Muscularis Externa + Auerbach’s plexus; - 2 concentric layers 3 layers: peristalsis Inner –oblique (extra layer than usual), upper third: Middle: Lower: 2 layers of muscle: skeletal Mixed Sm. Middle -circular - inner; circular Outer - longitudinal - outer; longitudinal voluntary Vol/invol Muscle involunta ry 4. Serosa or Adventitia Thin layer of CT covered with mesothelium Glands cardiac glands: gastric glands: - 4 types of cells within - around esophageal orifice Chief (Zymogenic cells): basophilic - mainly mucous • low columnar with zymogen granules (pepsinogen and lipase • base of cell; Parietal Cells: v. eosinophillic • secrete HCL, intrinsic factor (req. for Vit. B12 abs.) • b/w chief cells, and large cells • many mitochondria, no granules • secretory canaliculus, internal microvilli Mucous Neck cells • near gastric pit • numerous secretory granules of mucin Enteroendocrine cells • produce hormones: serotonin; gastrin phyloric glands: - short glands in phyloric region - coiled tubules of mucous cells Lecture 8 – S. Intestine/ L. Intestine General Plan: S. Intestine Description: - duodenum, jejunum, ileum - functions in digestion and absorption surface area is increased for absorption in 5 ways: 1. Length of s. intestine 2. plicae circularis: (valves of Kerckring) semicircular folds of submucosa 3. Intestinal Villi; finger like projections of epithelium 4. Microvilli (inc. S.A of epithelial cells) 5. glycocalyx; glycoprotiens (enterokinases – secreted from crypts of L) projecting from microvilli 1. Mucosa a. Epithelium; protective/ absorptive-secretory Simple columnar (2 types of cells:)@ villus 1. Columnar absorptive cells (brush border and glycocalyx, junctional complexes) 2. Goblet cells (apical region distended with mucigen droplets/ b. Lamina propria; LCT w/ lymphocytes -furthest level of the intestinal villi reticular connective tissue with lymphatic elements - central lacteal (lymphatic vessel – in the villi) - smooth muscle enters villus, expresses lacteal - crypts of Lieberkuhn (intestinal glands) invaginate from surface between villi) - upper half @ villus – absorptive/enterocyte, goblet, enteroendocrine cells) - Lower half @ crypt: • Panneth cells;secrete lysozyme, large apical, eosinophillic granules, basal ER • Undifferentiated columnar stem cells; migrate from base of crypt to villus tip – in 3 days. Billions of cells are shed every day and replaced by upward migration of cells from crypts • Enteroendocrine cells: secrete hormones such as Secretin, Cholecystokinin (CCK) towards basal lamina c. Muscularis Muscosae – thin layer of sm. Muscle 2. Submucosa Brunner’s glands – in duodenum: a. LCT w/ elastic fibres - compound tubular glands, produce mucus with an alkaline, bicarbonate content b. blood vessels + nerves + Meissner’s plexus - ducts penetrate muscluaris mucosae and empty into the crypts Peyer’s patches in Ileum - groups of lymphatic nodules - in lamina propria and submucosa - local source of lymphocytes (no lymph filtration by these nodules) 3. Muscularis Externa + Auerbach’s plexus; - internal circular, external longitudinal - peristalsis - Auerbach’s plexus: peristalsis 2 layers of muscle: - inner; circular - outer; longitudinal 4. Serosa or Adventitia - mesothelial cells on CT Glands Glycocalyx Myosin 1, F-actin, Calmodulin, Villin, Fimbrin Microvilli/ brush border Enterokinases (convert inactive enxymes into active enzymes) Trypsinogen, chymotrypsinogen, proelastase ƒ trypsin, chymotrypsin, elastase ƒ cascade of other enzyme activation ƒ breakdown of protein in s. intestine Terminal web IF, Actin filaments Intestinal Enterocyte villus Portal Vein Contains a.a, sugars and fatty acidsƒ goes to liver Lacteal Contains chylomicrons (what lipids are absorbed by) ƒ thoracic duct ƒ blood stream for distribution Artery Intestinal Gland/Crypt of Lieberkuhn L. Intestine Appendix - function: absorption of water and some digestions - small appendage of cecum close to ileum - intestinal walls: - small angular lumen, often contains debris • no villi - villi absent, epithelium as in colon • many long, straight crypts - lamina propria contains lymphoid tissue in continuous layer of nodules • surface epithelium is columnar absorptive plus many goblet cells - crypts not numerous, embedded in lymphoid tissue - muscularis externa without taeniae coli • Paneth cells absent • Other features similar to small intestine - typical serosa - many lymphocytes may be present, especially in lamina propria, but not • Muscularis externa neutrophils • Outer longitudinal layer localized into 3 longitudinal bands (taeniae coli) Lecture 12: Adrenal Thyroid and Parathyroid Gland: 1. distinguish between endocrine and exocrine glands giving examples. Endocrine Exocrine - ductless Attached by a duct to the surface into which their product is - secrete product into blood stream emptied - secrete hormones e.g. adrenals, thyroid, parathyroid, pituitary and e.g. testes, ovaries, and prancreas pineal 2. describe the location and organization of the adrenal gland. ADRENAL GLANDS - triangular bodies at the
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