the group project ~10 minutes/presentation 5 ‐ 7 slides: we are all about images ‐ no words...
TRANSCRIPT
THE ROAD MAP:
Today- 4/24: Digestive System & Immune System (4)
4/25, 4/26, 4/29: Consultations (Image data review)
4/26, 4/29, 5/1: Group In-class Presentations
Lab Practical: 4/23 and 4/24
Final Exam: 10:30 AM May 7th, 2013 ISB 221
Individual Project Written Papers: due Friday, 5/3
The Group Project~10 minutes/presentation5‐7 slides: We are all about images‐ no words needed!Organization and clarity are important so REHEARSE!
PRESENTATION GOALS:Identify yourselves.Introduce the histological features of your organ using your paraffin images.Orient the audience: planes of section etc.Introduce the markers you used and your predictions. Use your images to demonstrate what stained.Discuss your results including problems or artifactual staining.
Anxieties Are Us: The Group Project
• Hands-on opportunities• Not Cookbook! No guarantees.• Beauty is hard to achieve.• Some folks are just plain lucky.• Life is not fair. Get used to it.• Relax! Do your best. Work hard.• Tell the story- but briefly!• Accept responsibility.• Enjoy the ride.
Possible Artifacts
KNIFE MARKS
FREEZE/THAW DAMAGE
OTHERS:Uneven StainingFolded/wrinkled sectionParticulate debrisAntibody nonspecific staining
Enteroendocrine Cells- Hormonal release and nerve activity required for coordinating ingestion with secretion and motility
With ingestion of food:
Release of saliva
Release of digestive enzymes
Release of HCl
Release of bile from gall bladder
Motility of gastrointestinal tractWhat signals might trigger release of hormones and
digestive enzymes?
Stomach enteroendocrine cells release Gastrin:release from 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 is only part of the story………….
Small intestine enteroendocrine cells release Choleocystokinin (CCK): CCK released is stimulated by: presence of H+, amino acids, and fatty acids
- Pancreatic and gall bladder cells CCK receptors
- Release of bile from gall bladder into duodenum
- Release of digestive enzymes from pancreas
PANCREAS
PANCREAS: Endocrine / Exocrine Gland
http://www.uwgi.org/gut/stomach_03.asp
PANCREAS: Endocrine / Exocrine Gland
PANCREAS: Exocrine Gland
PANCREAS: Endocrine Gland
Islet of Langerhans: most numerous tail of pancreas, 2% volume
Pancreas: Islet of Langerhans
Pancreas: Endocrine Function
Cells: secretion of insulin in response to low blood glucose, causes uptake and storage of glucose into liver and skeletal muscle; diabetes mellitus Type I and II
Cells: secretion of glucagon in response to high blood glucose, causes synthesis of glucose and breakdown of glycogen in liver
Cells: secretion of somatostatin; inhibits insulin and glucagon release
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
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
LIVER
Right side, beneath diaphragmLobular“Hepatic”Functions: - Produce of bile - Process and store of nutrients- Phagocytose debris and bacteria
- Synthesize blood proteins and coagulation factors- Detoxify & inactivate drugs and toxic substances- Stores, modifies Vitamins A, D, K- Participate in iron metabolism- Modify hormones (thyroxine, growth hormone etc)
Blood Supply: Hepatic Portal System
TO LIVER: PORTAL VEIN: oxygen poor blood; from stomach, pancreas, spleen, & intestines.
HEPATIC ARTERY: brings oxygen rich bloodIN LIVER: HEPATIC SINUSOIDS (2nd capillary bed-portal system)
CENTRAL VEIN
HEPATIC VEIN
VENA CAVA
LIVER: Classic Hepatic Lobule
Hexagonal; connective tissue septaBounded by Portal Triads:
1) a branch of the hepatic artery2) a branch of the portal vein3) a bile ductule4) lymphatic vessel (not always present)
Central vein (terminal hepatic venule) in center
LIVER: Classic Hepatic Lobule bounded bt portal triads
LIVER: Portal Triad
LIVER: Portal Triad
LIVER: Hepatocytes- arranged in cords; separated by sinusoids
Perisinusoidal SpaceSPACE OF DISSE
Hepatocyte: 60% of all liver cells-polyhedral cells-microvilli: Space of Disse & bile canaliculi.- extensive ER- abundant
mitochondria
- storage granulesof glycogen
LIVER: SINUSOIDSDiscontinuous capillaries; Squamous endothelial cellsLittle or no basal lamina; Space of Disse
LIVER: SINUSOIDSKupffer Cells: protrude into sinusoids; contribute to endothelial lining; macrophages-like; remove blood cells, bacteria
Kupffer cells labeled with India Ink
LIVER: SINUSOIDS
Ito Cells (hepatic stellate cell):in perisinusoidal space stores Vitamin A-> retinol to form photopigment (rhodopsin) in eyerespond to liver inflammation and injury-->
scarNORMAL LIVER LIVER INJURY
LIVER: LIVER ACINUSLiver Acinus: Correlates with blood perfusion, metabolic activity and liver pathology; oriented around afferent vascular system
LIVER: LIVER ACINUSZones correspond to distance from blood supplyZone 1: closest to arterioles, highest oxygen, 1st toxin exposure, necosis due to toxins, first to regenerateZone 3: farthest from arterioles, poorest supply of
oxygen, necrosis due to ischemia
LIVER: BILE PRODUCTION
Bile Canaliculus: channel between adjoining
hepatocytes carries bile to bile duct
LIVER: BILE PRODUCTION
Flow of bile is opposite that of blood flow
LIVER: PORTAL LOBULE
Portal Lobule: Region of bile production drained by axial bile duct
Lymphatic System
- monitor body surfaces and internal fluids for antigens and materials for removal
- react to potentially harmful substances
Lymphatic Tissues
- Concentrated nearrespiratory tract
digestive tractreproductive tract
Antigen: foreign substance
Nonspecific Inflammatory Response
Mast cells-Histamine release-Vasodilation (increase capillary permeability)
Neutrophils-enzymatic digestion of virus
Macrophages-cytokine release-phagocytosis-antigen presentation
Specific Responses to Antigen Exposure:
Antigen-Presenting Cells (APCs):-APCs include: macrophages and B-
lymphocytes
1) endocytose and degrade antigens
2) display a portion of the antigen coupled to Major Histocompatibility Complex (MHC) II
molecules and on cell surface
3) activate other immune cells
Humoral Immunity Cell-mediated Immunity
Antibody Production Killing of Infected Cells
Humoral Immunity: Antibody Production
• Stimulation of B Lymphocytes (B cells)
• Antigen processing & presentation: B cells (MHC II)
• Stimulation of CD4 Helper T lymphocytes
• Production of Interleukins --> stimulate B cells
• B cell Proliferation --> Plasma cells & Memory cells
See also Figure 14.6 in Textbook re: CD40 and CD40L
Interleukins (ILs)
Humoral Immunity: Antibody Production
B-lymphocytes differentiate to form:• Plasma Cells: produce antibodies against a
single epitope1st exposure--> IgM2nd exposure--> IgG
• Memory cells: circulate for future encounters with antigen
Humoral Immunity: Antibody Production
Classes of Antibodies
With Second Exposure to Antigen:
Activation of Memory Cells specific for Antigen
Differentiate into Plasma Cells: produce IgG antibody
With Secondary Exposure to Antigen:immune response is fastermore antibody is produced more rapidlyantibodies bind antigen more strongly
Binding of Antibodies to Antigens Inactivates Them
Macrophage engulfs, processes & presents antigen
Stimulation of CD4 Stimulation of CD8 Helper T Lymphocytes Cytotoxic T Lymphocytes
MHC II MHC I
Release of Interleukin 2 ProliferationKilling of INFECTED cells
Cell-Mediated Immunity
Cytotoxic (CD8+) T-lymphocytes attack and destroy virus-infected cells
granzymes
1)Macrophage presents antigen to CD4+ and CD8+ T cells2)IL2 stimulates CD4+ and CD8+ proliferation3)CD8+ T cells recognize virus-infected cells (MHC I)4)CD8+ release granzymes plus5)Infected cells die by apoptosis
Cell-Mediated Immunity:Cytotoxic CD8 T-lymphocytes
Cytotoxic T Lymphocytes:- bind to target cell- exocytosis of granules of perforin and granzymes
- Perforins insert into target cell membrane
- Granzymes, serine proteases,
enter cell and cause cell death (apoptosis ) via activation of precursors of caspases.
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/CTL.htmlhttp://sprojects.mmi.mcgill.ca/immunology/Perforin.JPG
Natural Killer Cells: - recognize virus-infected or cancer cells- activated by antibody binding to Fc receptor- release perforin and granzymes, activate Fas- results in apoptosis (cell death)
Lymphatic Tissue and Organs
Lymphatic Vessels-more permeable than blood vessels-antigens gain entry, are carried to lymph
nodes
Lymph Nodes-at points of
convergence of lymphatic vessels Function:
-nonspecific filtering-maximize interaction
between APCs and antigens
Capsule
Afferent vessels
Hilum
Efferent vessels
ArteryVein
Lymphocyte Circulation: enter node from blood & lymph
vessel
LYMPH NODE
Lymph Node
What is the structure of the lymph node?
What is the pathway of lymph and lymphocyte movement through the node?
What is the pathway of blood movement through the node?
What cellsand specialized structers contribute to lymph node function?
Lymph Node Compartments Capsule
Cortex -lymphatic nodules B lymphocytes
Deep Cortex -T lymphocytes
Medulla
CapsuleCortex
Deep Cortex
Medulla
http://www.nature.com/ni/journal/v7/n4/fig_tab/ni1330_F1.html
Lymph Node Cortex
Lymphatic nodules (follicles)
Primary: - Naive B cells - Memory B cells
Secondary:–Inactive B cells - periphery–Activated B cells- germinal center–Follicular dendritic cells
Cortex: Lymphatic Nodules or Follicles
Follicular Dendritic Cells (arrows below)
• Found in germinal centers
• have Fc receptors
• bind antigen/antibody complexes
• processes contact B-lymphocytes
Dendritic Cells
-Antigen-presenting cells
-Activate T-cells
-Dendritic cells enter lymph mode in lymphatic vessels
-Locate in periphery of Follicle in lymph node
http://www.biken.osaka-u.ac.jp/COE/eng/project/images/fig-hirata-jpg.jpg
Lymph Node Deep Cortex (2)
• No Lymphoid nodules (5)• Almost all cells are T lymphocytes
• High endothelial venules
Lymph Node Medulla (3)• Medullary cords (4)• Medullary sinuses• B lymphocytes• Plasma cells• Macrophages
www.histol.chuvashia.com/atlas-en/lymphoid-en.htm
Medulla
Some lymphocytes:- Enter node in
lymph
Most lymphocytes:- enter node through High endothelial venules (HEVs)- migrate to the
superficial cortex and follicles
- proliferate after activation- otherwise
reenter circulation
High Endothelial Venule
- Plump endothelial cells
- Cell adhesion molecules
- Promote migration of lymphocytes from blood into node (extravasation)
- Mainly in deep cortex
- Release of chemokines
http://mcb1.ims.abdn.ac.uk/teaching/Honsdocs/Miyasaka.pdf
Lymphocyte movement through High
Endothelial Venules
“Selectins on a lymphocyte's microvilli cause it to slightly stick to endothelium and it slowly rolls along until integrin receptors at the tips are activated by chemokine to stick more firmly. The lymphocyte polarizes and begins squeezing into the space between two or more endothelial cells.”http://www.geocities.com/CapeCanaveral/Hangar/1962/page3.html#L02
The Fibroblastic Reticular Cell Conduit (FRCC)
- channels from HEVs in deep cortex; formed by fibroblastic reticular cells
- a conduit for movement of soluble molecules, such as chemokines and antigens, between the cortex and deep cortex
- channel contains ECM (collagens and proteoglycans) & adhesion proteins that promote T- and B-cell movement
Nature Reviews Immunology (Vol 3, No. 11, pp 867-878 (2003)
Lymphocytes migrate from blood or lymph to node
- B cells migrate to superficial cortex
- T cells migrate to deep cortex
After activation:
B lymphocytes--> plasma cells
Plasma cells ->medullary cords-> release antibody
Memory cells may return to the blood or lymph
Lymphocyte Movement