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Digestion Continued Pancreas and Liver Respiration

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1 Digestion Continued Pancreas and Liver Respiration
Histology 14 Digestion Continued Pancreas and Liver Respiration

2 Announcements Strike Extra Credit Research

3 Large Intestine (generic)
Principal functions: Recovery of HOH and salts from feces Propulsion of feces into rectum Also divided into three parts. Its total length is approx. 1.5 m long but it has a greater diameter than the small intestine. No villi Intestinal glands – mucus Crypts of Lieberkühn Surface epithelia – mostly goblet cells and absorptive cells Specialized muscularis externa Longitudinal muscle is separated into three independent bands

4 Anatomical Divisions of L. Intestine
Caecum: It is the blind end of the large intestine. Attached to it is the appendix. It is thought to play a role in fighting infection. Colon: Undigested food enters the colon and water and minerals are absorbed Intestinal bacteria help break down some of the undigested food so it can be absorbed. These bacteria also produce vitamin B12 and K as well as some amino acids Rectum and Anal Canal: Waste material (feces) moves into this region and is expelled through the anus.

5 Large Intestine

6 Long section of the colon (4x)

7 Long section of colon (100x)
2 main cell types: 1. goblet cells 2. absorptive cells


9 Sulculation caused by taeniae coli down to the anus – then continuous sheet of longitudinal muscle.

10 “End”notes Rectum – end of large intestine
Continuous sheet of long muscle Anus – switches back to strat squam. Goblet cells increase on way down.

11 Recto-anal junction

12 Section Epithelium Cell types in E. Other features
Esophagus Stratified squamous Squamous Submucosal glands Gradation of muscle Body / fundus Glandular – straight tubular Surface mucous cells Neck mucous cells Parietal cells Chief (peptic) cells Lymphoid sparse no aggregates Pylorus Glandular – coiled, branched tubular Mucous cells Occasional parietal Duodenum Glandular with villi and crypts of Lieberkühn Enterocytes with microvilli Goblet Cells Paneth Cells Brunner’s Glands Jejunum / ileum Peyer’s patches Colon / rectum Glandular – straight Goblet cells Absorptive cells Teniae coli Appendix Glandular – straight crypts Tall columnar cells Prominent lymphoid aggregates Anus Absorptive and goblet Squamous cells Colums of Morgagni Paneth Cells – lysozyme cells in bottom of crypts of lieberkuhn Colums of Morgagni – longitudinal folds in colon (non-distended) Peyer’s patches – lymphoid aggregates in colon Brunner’s glands – another name for the glands at the bottom of the crypts of Leiberkuhn in the duodenum Enterocytes – cells of epithelium

13 Pancreas and Liver Developmentally
Glandular outgrowth of primitive gut

14 Few notes on the Pancreas
In curve of duodenum Lobulated Gland separated by septa Exocrine Component – digestive enzymes from acini can’t secrete active form digest the gut secretes proenzyme form (inactive enzyme) Enterokinase (duodenal secretion) – activates proenzyme Endocrine Component – Hormones – sugar metabolism Insulin and Glucagon – decrease and increase blood sugar levels Islets of Langerhanz secreted into bloodstream lots of capillaries associated with islets

15 Central lumen Intercalated duct Intralobular ducts Interlobular ducts Pancreatic duct Ampulla of Vater Duodenum

16 Pancreas (45x)


18 Exocrine Acinus (8500x)

19 Liver Major functions Detoxification of metabolic waste (deamination of amino acids – urea), drugs, toxins, alcohols Destruction of spent RBCs and reclamation of their constituents (spleen does this too) Synthesis and secretion of bile (consists of above) Synthesis of lipoproteins, plasma proteins (including albumin and clotting factors) Synthesis and storage of glycogen

20 Liver Largest gland in body (1500g)
Divided into 4 lobes (R, L, quadrate and caudate) Endocrine and Exocrine components Both are roles of the hepatocytes (liver cells) Exocrine – bile Endocrine – lots of stuff – added to sinusoids of hepatic lobules Plus, noxious conversions added to bile Intraperotineal


22 Pig liver (20X) C

23 Human (20X)


25 PV – portal venule A – hepatic artery L – lymphatic duct B – bile duct
S – sinusoids Limiting plate Limiting plate – specialized hepatocytes surrounding the portal tract (triad)

26 Respiratory System Main functions: Conducts air in/out
Exchange gasses w/blood – respiration Includes mechanisms to prevent collapse of conducting tubes Bones Cartilage Two major tube types: Conducting pathway (nasal portion – lungs) Respiration pathway (area of alveolar sacs)

27 Conducting Pathway Specialized lining of epithelium
“respiratory” epithelium that changes with arborization Pseudostratified ciliated columnar epithelium With goblet cells – secrete lots of mucus Cilia beat in one direction: Above pharynx – beat downwards Below pharynx – beat upwards Mucocilary escalator Mucus moved throughout passageway – trap dust

28 Conducting Pathway (cont.)
Blood vessels – warm and moisten air Trachea (main passageway): Contains C-shaped rings in adventitia R,L primary bronchi (enter lungs) Same as trachea Cartilage becomes reduced in bronchi of lungs Epithelium – begin with pseudostrat ciliated to ciliated columnar Bronchioles Epithelium – ciliated cuboidal to non-ciliated simple squamous Terminal bronchioles Respiratory bronchioles – start of the respiratory pathway Decrease in cartilage, glands, goblet cells height of epithelium Increase in smooth muscle and elastic tissue Extrapulmonary- Intrapulmonary-



31 Drawings of gas exchange

32 Trachea xs

33 Trachea ls E – epithelium LP – lamina propria SM – submucosa
F – fibroelastic tissue

34 Primary bronchus E – epithelium LP – lamina propria M – smooth muscle
G – seromucous glands C – cartilage Goblet Cells in epith.

35 Bronchiole V – vein M – sm. Muscle

36 Terminal portion of respiratory tree
T – terminal bronchiole R – respiratory bronchiole V – pulmonary vessel AD – alveolar duct AS – alveolar sac A - alveolus

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