ANNOUNCEMENTS

SECOND EXAM: Wednesday, April 22ndMaterial Covered: Bone, Muscle, Nerve & Circulatory, Lymphatic, & Urinary Systems

REVIEW SESSION TODAY, 4/21 6-7PM ISB 364

LAB PRACTICAL RESCHEDULED: April 28, 29Material Covered: Urinary, Exocrine, & Endocrine Systems, Digestive System & Accessory Organs, and Lymphatic System and Reproductive Systems.

Final Exam: May 18th 1:30 PM in Morrill 203

LAB SCHEDULE

Week of April 20: Work in lab group to, choose organs, complete frozen sections, design immunohistochem. Experiment.

Week of April 27: Lab Practical and learn to section embedded material.

Week of May 4: Immunohistochemistry. Complete sectioning & staining of embedded material.

In class, May 11: Share results, discuss interpretation.

May 18: Lab Project report due at Final Exam.

*BIOLOGY SENIORS*

Join us for lunch!

12 Noon Wednesday, May 13th

Lawn, Durfee Conservatory

Anatomy of the Stomach

3 regions:

Cardiac

Pyloric

Fundic

Rugae: longitudinal folds or ridges on inner surface

Each stomach region

has distinctive glands.

•Cardiac glands

•Pyloric glands

•Fundic glands

-gastric pits

-isthmus cell replication

-neck

-base or fundus

Anatomy of the Small Intestine

3 components: Duodenum, Jeunum, Ileum

- Plicae circularis- Villi- Microvilli

- Simple columnar epithelium

Anatomy of the Small Intestine

Secretion / Digestion / Absorptionepithelial cells and associated glands salivary glands pancreas gall bladder stomach small & large intestine

Secretions include: antibodies: IgA lubricants hydrochloric acid digestive enzymes hormones water

Secretion / Digestion / Absorption

- initiated in mouth- stomach lumen- completed in small intestinal lumen

- aided by HCl from stomach- amylase from saliva & stomach- pancreatic enzymes- enzymes in glycocalyx of small intestine- aided by bile from gall bladder

Secretion / Digestion / Absorption

across epithelium of

small intestine and

large intestine

10.

Lubrication: Mucous Secretions

Esophagus- Lubrication and protection from regurgitation of acidic stomach contents

Stomach- surface mucous cells; mucous protects from abrasion, contains bicarbonate; protects mucosa from acidic stomach contents (chyme)

Small Intestine- goblet cells, # increases from duodenum=> ileum

Large Intestine- goblet cells, # increases toward rectum

Mouth Stomach Small Large Intestine

Intestine

Carbohydrate

Protein

Lipids

Nuclei Acids

Digestive Secretions Digestive Secretions from Pancreas

Absorption Bile from gall bladder

Specialized Cells for Stomach Secretion

Surface Mucous Cells: gastic pit and neck of gastric gland

PAS stain for carbohydrates

millette.med.sc.edu/Lab%201%20pages/introduct...

Specialized Cells for Stomach SecretionParietal (Oxyntic) Cells:- neck & deep parts of fundic glands

- release HCl and intrinsic factor (B12 absorption)

- large

- triangular

- acidophilic

Parietal (Oxyntic) Cells

Anti-parietal cell antibody

Parietal (Oxyntic) Cells

HCl Synthesis: H+ and Cl- ions pumped into intracellular canalicular system, HCl formed

http://www.mfi.ku.dk/ppaulev/chapter22/images/22-10.jpg

Specialized Cells for Stomach Secretion

Chief Cells: deep in fundic glands, protein-secreting, lots of RER, basophilic, zymogen granules

Secrete pepsinogen HClPepsinogen--------->

Pepsin

Specialized Cells for STOMACH Secretion

Enteroendocrine cells: small - more common in gland base - pale, vesicles don’t fix well - may not reach lumen, but sample lumenal contents with microvilli -release variety of hormones into blood

Enteroendocrine cells

Small IntestineIncreased Surface Area:Plicae circularis, Villus, Intestinal Gland (Crypts of Lieberkuhn)

Villus: Capillary Lacteal (lymphatic capillary) Smooth muscle

Plicae circularis: transverse folds with core of mucosa

Small Intestine: Villi and Crypts of Lieberkuhn

Specialized Cells of the Small Intestine

Enterocytes (intestinal absorptive cells)

Paneth cells- secrete antimicrobial substances

Enteroendocrine cells- release hormones

M cells- dome cells cap lymphatic nodules

Goblet cells- mucous secreting

Enterocytes (intestinal absorptive cells)

Tall columnar cells

Microvilli=>striated border

Epithelial specializations-Terminal web- Tight junctions

Secrete Digestive Enzymes

Paneth Cells

- base of intestinal glands- large- intense acidophilic granules- phagocytose bacteria- secrete lysozyme- digests bacterial cell wall

Epithelial Renewal in Stomach and Small Intestine

Large Intestine

Simple columnar epitheliumAbsorption of water and electrolytes

Columnar absorptive cellsCrypts of LieberkuhnGoblet cells

www.kumc.edu/.../histoweb/gitract/gi21.htm

Secretion / Digestion / Absorption

- Requires coordination of secretion and motility with ingestion

NERVOUS AND HORMONAL SIGNALS

Secretion / Digestion / Absorption

- Requires coordination of secretion with ingestion

NERVOUS AND HORMONAL SIGNALS

Release of saliva

Release of digestive enzymes

Release of HCl

Release of bile from gall bladder

Motility of gastrointestinal tract

Secretion / Digestion / Absorption

What signals might trigger release of

hormones and digestive enzymes?

Gastrin secretion: release from stomach enteroendocrine cells (G cells) is stimulated by

1) peptides and amino acids in stomach lumen2) distention of stomach wall3) sensory inputs --> neural innervation (GRP)

- Parietal cells have gastrin receptors

GASTRIN RELEASE

HCl RELEASE

PEPSIN ACTIVATION

PROTEIN DIGESTION

Regulation Parietal Cell HCl secretion

http://www.uwgi.org/gut/stomach_03.asp

Gastrin produced by G cell

HCl produced by parietal cell

Choleocystokinin (CCK): hormone released from enteroendocrine cells of small intestine is stimulated by presence of H+, amino acids, and fatty acids

- Pancreatic cells have CCK receptors**(may act through neurons innervating the pancreas in humans)

CCK RELEASE (INTESTINAL ENDOENDOCRINE CELLS)

PANCREATIC DIGESTIVE ENZYME RELEASE

DIGESTION OF CARBOHYDRATES, PROTEINS, LIPIDS IN SMALL INTESTINE

PANCREAS

PANCREAS: Endocrine / Exocrine Gland

http://www.uwgi.org/gut/stomach_03.asp

PANCREAS: Exocrine Gland

http://www.uwgi.org/gut/stomach_03.asp

PANCREAS: Exocrine Gland

PANCREAS

Islet of Langerhans

Choleocystokinin (CCK)

-Gall Bladder smooth muscle cells have CCK receptors

CCK RELEASE (INTESTINAL ENDOENDOCRINE CELLS)

GALL BLADDER CONTRACTION

RELEASE OF BILE INTO LUMEN OF SMALL INESTINE

FACILITATED DIGESTION OF LIPIDS

GALL BLADDER

GALL BLADDER

- lumen lined by simple columnar epithelium

- microvilli, tight junctions, mitochondria

- smooth muscle

- concentrates bile (Na+ actively pumped out of lumen in exchange for H+, water follows)

- stores bile until release