Transcript Document

Histology 14
Digestion Continued
Pancreas and Liver
Respiration
Announcements
1. Strike
2. Extra Credit
3. Research
Large Intestine (generic)
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Principal functions:
1.
2.
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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
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Crypts of Lieberkühn
Surface epithelia – mostly goblet cells and absorptive
cells
Specialized muscularis externa
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Longitudinal muscle is separated into three independent
bands
Anatomical Divisions of L. Intestine
1.
Caecum:
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2.
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:
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3.
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:
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Waste material (feces) moves into this region and is expelled
through the anus.
Large Intestine
Long section of the colon (4x)
2 main cell types:
1. goblet cells
2. absorptive cells
Long section of colon (100x)
• 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
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2.
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Central lumen
Intercalated duct
Intralobular ducts
Interlobular ducts
Pancreatic duct
Ampulla of Vater
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)
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PV – portal venule
A – hepatic artery
L – lymphatic duct
B – bile duct
S – sinusoids
Limiting plate
Respiratory System
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Main functions:
– Conducts air in/out
– Exchange gasses w/blood – respiration
– Includes mechanisms to prevent collapse of
conducting tubes
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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
Mucocilary
escalator
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)
• Extrapulmonary– Same as trachea
• Intrapulmonary– 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
Drawings of gas exchange
Trachea xs
Trachea ls
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E – epithelium
LP – lamina propria
SM – submucosa
F – fibroelastic tissue
Primary bronchus
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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
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T – terminal bronchiole
R – respiratory bronchiole
V – pulmonary vessel
AD – alveolar duct
AS – alveolar sac
A - alveolus