histology 14 digestion continued pancreas and liver respiration
TRANSCRIPT
Histology 14
Digestion Continued
Pancreas and Liver
Respiration
Announcements
1. Strike
2. Extra Credit
3. Research
Large Intestine (generic)
• Principal functions:1. Recovery of HOH and salts from feces2. 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
Anatomical Divisions of L. Intestine
1. 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.
2. 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
3. Rectum and Anal Canal: – Waste material (feces) moves into this region and is expelled
through the anus.
Large Intestine
Long section of the colon (4x)
Long section of colon (100x)2 main cell types:
1. goblet cells2. absorptive cells
• Sulculation caused by taeniae coli down to the anus – then continuous sheet of longitudinal muscle.
“End”notes
• Rectum – end of large intestine– Continuous sheet of long muscle
• Anus – switches back to strat squam.
• Goblet cells increase on way down.
Recto-anal junction
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
Lymphoid sparse no aggregates
Duodenum Glandular with villi and crypts of Lieberkühn
Enterocytes with microvilli
Goblet Cells
Paneth Cells
Brunner’s Glands
Jejunum / ileum Glandular with villi and crypts of Lieberkühn
Enterocytes with microvilli
Goblet Cells
Paneth Cells
Peyer’s patches
Colon / rectum Glandular – straight Goblet cells
Absorptive cells
Teniae coli
Appendix Glandular – straight crypts Goblet cells
Tall columnar cells
Prominent lymphoid aggregates
Anus Glandular – straight
Stratified squamous
Absorptive and goblet
Squamous cells
Colums of Morgagni
Pancreas and Liver
• Developmentally– Glandular outgrowth of primitive gut
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
1. Central lumen2. Intercalated duct3. Intralobular ducts4. Interlobular ducts5. Pancreatic duct6. Ampulla of Vater7. Duodenum
Pancreas (45x)
Exocrine Acinus (8500x)
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
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
Pig liver (20X)
• C
Human (20X)
• PV – portal venule
• A – hepatic artery
• L – lymphatic duct
• B – bile duct
• S – sinusoids
• Limiting plate
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:1. Conducting pathway (nasal portion – lungs)
2. Respiration pathway (area of alveolar sacs)
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
Mucocilaryescalator
Mucus moved throughout passageway – trap dust
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-
Drawings of gas exchange
Trachea xs
Trachea ls
• E – epithelium
• LP – lamina propria
• SM – submucosa
• F – fibroelastic tissue
Primary bronchus
• E – epithelium• LP – lamina propria• M – smooth muscle• G – seromucous
glands• C – cartilage• Goblet Cells in epith.
Bronchiole
• V – vein
• M – sm. Muscle
• Terminal portion of respiratory tree– T – terminal bronchiole
– R – respiratory bronchiole
– V – pulmonary vessel
– AD – alveolar duct
– AS – alveolar sac
– A - alveolus