ANSC 230 Exam 6 Lecture Notes + Sample Exam Questions

Differentiate between the endocrine and exocrine portions of the pancreas. What are the major cell types that compose these two portions, and what substances do these two portions produce?

Endo: has to be released into blood stream to act on body, Alpha and Beta cells, release glucagon and insulin respectively. Exo: substances routed to tissues by ducts, do NOT enter blood, produce bicarbonate and zymogens, routed directly from pancreas to duodenum, bicarbonate = neutralization of pH, enterokinase acts on trypsin and zymogens

Where are the parietal cells located and what do they do to facilitate digestion.

Gastric glands contain specialized cells called parietal cells. They produce HCl in response to several stimuli, including acetylcholine release, which in turn helps with breakdown of food.

Alkaline Tide

In gastric parietal cell, HCO3- leaves the cell in exchange for Cl- going in the cell to balance the pH.

Provide a overview of how cellulose is digested in cattle. Be certain to explain where cellulose is digested, how it is broken down and what the end-products of cellulose breakdown are. How does digestion of cellulose differ when it is digested in the horse?

In rumen, by fermentation, microbes will break down plant matter and yield volatile fatty acids, and gasses release (CO2 and Methane released). After this, then the digesta moves into true stomach to undergo chemical digestion. In a nonruminant, proceeds through chemical digestion in stomach, through the GI tract, and then into the caecum.

How does mammalian blood cell production differ between the mammalian fetus and an adult mammal (that is, what are the respective sites of blood cell formation at these different stages of development)?

In the fetus, blood cells are produced by the liver, spleen and bone marrow, while in adults blood cells are produced by the bone marrow.

Innate vs

Innate: physical barriers to pathogens, mucus, etc. Adaptive: antibody-mediated response

Describe the structure of the muscularis of the intestine.

It is composed of elastic fibers and smooth muscle cells, generally arranged in an outer longitudinal and inner circular layer.

Describe how the structure of the mucosa in the intestine facilitates absorption of nutrients, what are the key anatomical features that allow absorption to occur.

Large amount of surface area in intestine, comes from 1) folds in mucosa (villi) and 2) enterocytes have microvilli on cell surface that faces lumen, and they cover the entire mucosa.

What differences would you expect to observe if you compared blood samples from a healthy individual and an individual with a disease known as lymphoblastic leukemia? Provide a clear rationale to support your answer.

Leukemia: blood cancer Cells from that tissue reproducing in an uncontrolled manner, begin to lose identity, crowding out healthy cells. Most patients with AML have too many nonfunctional lymphocytes in their blood, and not enough red blood cells or platelets.

Describe the structure of the mucosa of the intestine. Relate how the specialized structures in the mucosa facilitate nutrient absorption.

Made up of enterocytes with microvilli, contain folds with villi, inside villi are capillary beds and central lactile. Villi and microvilli increase surface area for absorption.

Describe how micelles in the lumen of the intestine ultimately bring nutrients into the blood circulation.

Micelles are formed by emulsified bile, enterocytes absorb micelles which produces chylomicrons,

What are the major processes that occur in the duodenum, jejunum and ileum?

Mostly digestion and absorption of water and nutrients. The duodenum does both digestion and absorption, the jejunum digests, and the ileum absorbs any final material not absorbed by the duodenum. Order: duodenum, jejunum, ileum.

Outline how swallowing is mediated. Be certain to explain what happens during the oral (voluntary) phase, the pharyngeal phase, and the esophageal phase.

Oral: where animal has taken food into mouth, created bolus, and pushes to back of pharynx, stimulates receptors to release NO, VIP, see contraction of oral cavity so food is begun to be pushed down. Pharyngeal: pushed down, sphincter closes Esophageal: Acetylcholine, NO, VIP release, pushed into stomach, sphincter closes

Why does plasma have a yellow color?

Plasma is yellow because it contains bilirubin, a breakdown product of hemoglobin.

T-cells are immune cells that are made in the bone marrow. Where do T-cells mature?

T-cells mature in the thymus.

What are the names of the three major salivary glands?

The sublingual (under tongue), the mandibular (lower jaw area), and the parotid (near ear).

How are pancreatic secretions and bile delivered to the gastrointestinal tract; what location in the gastrointestinal tract are these substances added?

They empty into the duodenum, so location is also duodenum.

Morphology of Intestine

(see photo)

Ruminants

- 4 components - Reticulum - Omasum - Rumen - Comprise what is referred to as the "forestomach": fermentation occurs here - Rumination - Regurgitation; remastication; resalivation; reglutition: 8 hour cycle

Digestion

- Breakdown of foods by chemical and physical processes to yield components that can be absorbed by the body

Teeth

- Incisors (cutting) - Canines (tearing) - Premolars (grinding) - Molars (grinding)

Gut motility

- Peristaltic contractions - "Slow waves" - Interstitial cells of cajal: pacemaker cells of the GI tract - Acetylcholine: increase strength and frequency of contractions - NO (nitric oxide) and VIP (vasoactive intestinal polypeptide): decrease strength and frequency of contractions - Enteric Nervous Systems - Meissner's plexus (submucosal plexus) - Under mucosa (brush border) - Control capillary beds in GI tract, secretions by mucosa, lymphatics - Auerbach's plexus (myenteric plexus) - Within the muscularis of GI tract - Controls contractility of GI tract

Immunity

- Physical barrier - Mucus - Acquired immunity - T cells and B cells - Antibodies activate T cells; target pathogens for destruction - Major Histocompatibility Complex II (MHCII) - Antigen presentation - Found on antigen presenting cells: dendritic cells, macrophages, B-cells - B-cells present antigens using MHCII - recognized by T- cells - cytokines released - activate B-cells (form plasma cells), release antibodies

Blood composition

- Plasma: liquid fraction of blood -contains water, triglycerides, fats, carbohydrates, ions, proteins, dissolved gases, hormones, and wastes - Cells are in the formed elements - Erythrocytes (RBCs) - Leukocytes (WBCs) -Thrombocytes (platelets)

Tongue

- Positive bolus of food for swallowing

What is chemotaxis?

Cellular movement that requires a chemical gradient and requires the cells to make physical contact with said gradient. Immune cells typically move by chemotaxis, as an example.

Where are Meissner's plexus and the Auerbach plexus located? What part of the nervous system do they belong?

Clusters of neurons associated with GI tract. Messiner's located under mucosa but on top of smooth muscle of GI tract. Auerbach plexus clustered in between layers of smooth muscles, regulates contractility. Both branches of enteric nervous system.

How do nitric oxide and acetylcholine impact contraction of the gastrointestinal tract?

decrease frequency and amplitude of slow waves.

How would bile production and transport be impacted if the Kupffer cells were damaged and not able to function at 100% capacity? Provide a clear rationale to justify your answer.

( probably not a likely question ) Will not be impacted because Kupffer cells do not play a role in bile production and transport.

Location of Auerbach's plexus and Meissner's plexus

(see photo)

Morphology of Liver

(see photo)

Small intestine

- 3 regions: - Duodenum (primarily digestion) - Jejunum (primarily absorption) Ileum (primarily absorption) - Enteroendocrine cells - Produce cholecystokinin (CCK) - Amino acid metabolism - Fatty acid breakdown - Promote release of pancreatic enzymes - Promote gall bladder emptying - Inhibit stomach emptying - S cells (duodenum and stomach) - Produce secretin (low pH stimulates secretin release) - Secretin causes pancreatic enzyme release and bicarbonate release to GI tract - Secretin blocks the H2 receptors in parietal cells

Erythropoietin (EPO)

- A glycoprotein secreted by the kidney and stimulates erythropoiesis in the bone marrow - Under hypoxic conditions, the kidney will produce and secrete erythropoietin to increase the production of red blood cells - Erythropoietin (EPO) binds to the erythropoietin receptor (EPO-R) on the surface of progenitor cells. This results in differentiation and proliferation of the erythroid cell line

Spleen

- Blood flows through the spleen-removes damaged cells - Storage site for red blood cells - Activating lymphocytes - Capsule: outer covering - Trabeculae: elastic fibers and smooth muscle (houses arteries, veins, and nerves) - Parenchyma (splenic pulp) - Red pulp - Reticular mesh network - Fixed macrophages & collagen fibers - Venous sinusoids - Packed red blood cells - White pulp -Lymphocytes (~25% of body's B-cells and T-cells)

How immune cells travel

- Carried in blood - Diapedesis - Small fenestrations form in capillary wall, allows cells to emerge - Ameboid movement - Cells physically interacting with surrounding tissues - Chemotactic signaling - Via chemical messages - Examples: interferons; act in small quantities; activate NK cells and macrophages in response to viral infection

Mastication

- Chewing food into a bolus that can be swallowed

Absorption details

- Chyme: contents from stomach that enters the intestine - Large amount of surface area in small intestine: allows for efficient absorption - Villus (singular)/villi (plural) are found throughout small intestine - Villi are covered in epithelial cells called enterocytes (enterocytes are covered by microvilli) - Villi covered by cells within microvilli increase surface area of intestine ~600x - Referred to as the "Brush Border"

Hemostatic regulation

- Damaged blood vessel - Vasoconstriction - Endothelial cells activated - Dissociate - Increase in number - Thrombocyte activation - Form projections on surface - Cluster together - Clot formation - RBC WBC trapped in clot - Remodeling of clot

Pancreas

- Endocrine portion - a cells (glucagon release); b cells (insulin release) - Exocrine portion - Acinar cells (digestive enzymes) - Most are zymogens or "proenzymes"(inactive forms of enzymes) - Example: Trypsinogen. When trypsinogen is acted upon by enterokinase, which is made by enterocytes in the GI tract, it becomes trypsin. Trypsin breaks down peptides - Ductal cells (bicarbonate) - Role in neutralizing pH in GI tract (chyme has very low pH from stomach acid)

Prehension

- Grabbing and grasping of foods with the tongue, teeth, and lips

Hematopoiesis (common lymphoid progenitor cell)

- If leaves bone marrow: - Forms NK cells (reside in spleen, tonsil, thymus, lymph nodes) - If stays in bone marrow: - Forms B cells (reside in circulation) - Forms T cells (to thymus for maturation) (seen in lymphatic system, spleen, and blood vessels) - Collectively...process of forming NK cells, B cells, and T cells is referred to as lymphopoiesis

5 Classes of Antibodies

- Immunoglobulins - IgG, IgD, IgM, IgE, IgA (will only need to know names) - Functions - Agglutination - Recruitment of NK cells and macrophages - Neutralization - Opsonization - Activation of Compliment System (proteins that exist inactively, only activated when foreign substance is recognized, activated to begin attack on foreign substance) - Innate immune system, compliment cascade; active a series of pro-proteins that result in cell lysis

Anemia

- Iron deficient anemia - Insufficient iron in the diet, interferes with hemoglobin production - Lower RBC numbers - Megablastic anemia - Deficiency in Vitamin B12 - Vitamin B12 critical for erythropoiesis - Macrocytes (abnormal red blood cells), last ~30-50 days, instead of 110 days - Pernicious anemia - Atrophy of part of gastric mucosa (lose parietal cells); these cells produce "intrinsic factor", which is critical for Vitamin B12 absorption - Blood loss: if chronic, individual cannot make hemoglobin fast enough - Aplastic anemia: non-functional bone marrow

Leukemia and leukopenia

- Leukopenia - Lower than expected proportion of white blood cells in circulation - Lymphoblastic leukemia - Cells derived from common lymphoid progenitor cell - Myeloid leukemia - Cells derived from common myeloid progenitor cell

Lymphoid organs/tissues

- Lymph nodes: - Dendritic cells, lymphocytes (B-cells & T-cells), fixed macrophages - Thymus - Tonsils - MALT (Mucosa Associated Lymphoid Tissue) - Spleen - Contain trabeculae

Hematopoiesis (common myeloid progenitor cell)

- Megakaryocyte (thrombopoiesis) - Thrombocytes (platelets) - Proerythroblast (erythropoiesis) - Reticulocyte - Mast cell: histamine production - Myeloblast - Basophils (granulopoiesis) - Eosinophils (granulopoiesis) - Neutrophils (granulopoiesis) - Macrophages (monopoiesis)

Absorption

- Movement of nutrients from the lumen of the gastrointestinal tract (GI tract) into epithelial cells of the GI tract, and ultimately into the blood stream

Hematocrit (packed cell volume (PCV))

- Percentage of blood volume occupied by red blood cells - Normal: ~42-45% - Polycythemia: too many RBCs - Anemia: too little RBCs - A buffy coat is a mix of lymphocytes, monocytes, granulocytes, and platelets, isolated from plasma and RBCs by centrifugation

Erythropoiesis

- Process of making red blood cells - The red blood cells of mammals are typically shaped as biconcave disks and anucleate when mature - They live in blood circulation for about 110-120 days - Erythropoiesis involves proliferation and differentiation of small population of hematopoietic stem cells resident in the bone marrow (liver, spleen and bone marrow in fetus) into mature red blood cells

Salivary glands

- Produce saliva - Locations include: - Sublingual (under tongue) - Mandibular (lower jaw area) - Parotid (near ear) - Saliva contains the enzyme amylase - Hydrolyzes a1-4 linkages in starch (an oligosaccharide) - Mucus - Viscous; lubricates and protects epithelial cells that line the GI tract - Urea - Nitrogen source for rumen bacteria - Anti-foaming properties

Bilirubin

- Produced as a breakdown product of hemoglobin, gives plasma its yellow coloring - Jaundice is a yellowing of the skin and the whites of eyes that happens when the body does not process bilirubin properly

Differentiate between an antigen and an antibody.

An antigen is any substance that prompts your body to trigger an immune response against it. Antigens include allergens, bacteria and viruses. Antibodies are Y-shaped proteins that the body produces when it detects antigens. Antibodies are produced exclusively by immune cells called B cells.

Explain how digested fats from the lumen of the intestine enter the circulatory system. Be certain to discuss the key substances produced by the body that allow fats and lipids.

Bile emulsifying the fats in lumen of intestine, which produces micelles, absorbed by enterocytes, will enter cytoplasm of enterocytes, enterocytes will convert micelles into chylomicrons. chylomicrons secreted by enterocytes into interstitial space into villi of intestine. Once they are in the inter. space, chylomicrons picked up by central lactile (lymphatic system) and then routed to blood in hepatic portal vein.

What are the major gasses that are given off by the rumen during fermentation?

CO2 and Methane. Important products are volatile fatty acids, which CAN become gasses.

Distinguish between the processes of digestion and absorption.

Digestion is the physical breakdown of food particles, while absorption is the body intaking vitamins, molecules, and whatever else can be derived from the physically broken down food particles.

Inflammation is an immediate response to tissue damage that can involve localized redness, pain, and swelling; inflammation can also cause fever. Explain how blood vessel dynamics are altered during inflammation.

Tissue is inflamed, increase in blood flow (vasodilation). As a result of the vasodilation, we see an increase of blood going to tissue, more opportunity for plasma to leave into interstitial fluid, causes swelling (edema). In addition to swelling, chemical signals are released to bring in immune cells, which can also release further chemicals that could also add to the remodeling.

Where are the upper esophageal sphincter and the lower esophageal sphincters located, what are their roles, are the generally open or closed?

Upper: between pharynx and esophagus. Lower: between esophagus and stomach. Normally closed, only open when bolus is passing through/ NO and VIP cause sphincters open. Role is for swallowing.

Liver

- Produces bile (bile is typically stored in the gall bladder) - Bile salts, bicarbonate, bilirubin (makes the bile yellowish), cholesterol, water - Common bile duct - Transports bile from liver/gall bladder to GI tract; joins intestine at Sphincter of Oddi - Bile emulsifies (combine) fats - Form micelles (fats that have become emulsified, have been formed into small spheres) that can be absorbed by brush border - Enterocytes absorb micelles, produce chylomicrons. - Chylomicrons excreted to center of villus - Capillary network and lymphatic vessel (central lacteal) - Absorbed chylomicrons move to liver by hepatic portal vein - Hepatic Portal Vein (brings absorbed nutrients from GI tract to liver) - Liver absorbs nutrients - Liver recycles bile salts - Liver (and kidney) detoxifies blood - Liver sinusoids- lined by hepatocytes (liver cells that absorb nutrients and bile salts) and Kupffer cells (fixed immune macrophages, resident in liver sinusoids) - Liver sinusoids connect to central vein of liver, which then joins to the vena cava. - Blood flows through liver sinusoids (i.e., blood from hepatic portal vein moves through the liver sinusoids to the central vein of the liver, then the blood is routed to the vena cava, and back to the heart). - Opposites side of hepatocytes from the liver sinusoids are the bile canaliculi - These connect to the common bile duct and transport bile - Horses do not have a gall bladder, and so bile goes straight from liver to GI tract

Stomach

- Regions - Cardia (entrance) - Fundus (dome shaped region) - Body (middle portion) - Pyloric region (near junction between stomach and intestine) - Gastric glands-various types, contain specialized cell types including: - Parietal cells - Produce HCl (proton pumps H+/K+ ATPases) in response to several stimuli, including acetylcholine release - G cells - Produce gastrin in response to acetylcholine (acts on parietal cells, chief cells, and ECL cells) - Gastrin acts on parietal cells - stimulate HCl release - Chief cells - Produce pepsinogen (upon stimulation by gastrin) - When exposed to HCl, converts pepsinogen into pepsin: an enzyme that breaks down protein - Enterochromaffin-like (ECL) cells - Produce histamine (upon stimulation by gastrin) -Histamine acts on the H2 receptor on parietal cells (causing HCl release) - Tagamet: H2 receptor antagonist - Prilosec: inhibits H+/K+ ATPases

Hematopoiesis - first step

- Start with hemocytoblasts in bone marrow (a stem cell)

Deglutition

- Swallowing of bolus of food

Interstitial fluid transport

- The lymphatic pathway is an open circuit where lymphatic capillaries in body tissues reabsorb interstitial fluid (interstitial fluid is derived from blood plasma). - This lymph ultimately returns to the blood plasma (blood plasma in capillaries -> interstitial fluid -> lymph in lymphatic pathway -> lymph returns to blood plasma)

3 Phases of Swallowing

- Voluntary phase (oral phase) - Bolus pushed to pharynx (voluntary) - Touch receptors activated (afferent neurons signal to medulla; motor neurons release acetylcholine) - Pharyngeal phase - Pharynx contracts, pushes bolus to upper esophageal sphincter (UES) - Nitric Oxide (NO) and Vasoactive Intestinal Peptide (VIP) cause the UES to relax - Esophageal phase - Bolus passes by UES - Acetylcholine release causes smooth muscle of esophagus to contract (peristaltic contractions) - Bolus arrives at lower esophageal sphincter (LES) - NO and VIP allow LES to relax-bolus to stomach - Achalasia: failure to relax the LES

Lymph nodes

1) Afferent lymphatics carry lymph to the lymph node from peripheral tissues 2) The afferent vessels deliver lymph to a meshwork of reticular fibers, macrophages, and dendritic cells. Dendritic cells are involved in the initiation of the immune response 3) Within the lymph node, lymph flows through regions containing both B cells and plasma cells 4) Efferent lymphatics leave the lymph node and carry lymph toward the venous circulation

Lymphatic capillaries

1) Run parallel to blood capillaries in all body tissues 2) Incomplete basement membrane, endothelial cells overlap one another 3) Low pressure allows interstitial fluid to enter lymphatic capillaries 4) Once interstitial fluid enters lymphatic capillaries, it is no longer called "interstitial fluid," but rather we call it "lymph". 5) Lymph moves from lymphatic capillaries, to afferent lymph vessels, to lymph nodes, to efferent lymph vessels, to venous circulation

3 Classes of Lymphocytes

1) T cells (~80%) a) Cytotoxic T cells (CD8+) b) Helper T cells (CD4+) c) Suppressor T cells (not CD8+, not CD4+) d) Memory T cells (either CD8+ or CD4+) 2) B cells (~10-25%) a) Plasma cells b) Memory B cells 3) Natural killer (NK) cells (~5%) - Immune surveillance

Outline how hemostasis is maintained when a blood vessel is damaged.

3 major things happening at the same time: vasoconstriction first thing, immediate, such that less blood flows through that blood vessel. Activation of thrombocytes (platelets) that cluster and stick together due to projections on their cell membrane (change in cell membrane that allows clustering), makes a clot. Third step is activation of endothelial cells (make lining of blood vessel) (angiogenesis). They disassociate and seal over damage caused on vessel.