Immune and Lymphatic Systems

• Here are study notes based on the provided questions.

Immune System Functions

• Protects the body from pathogens, foreign substances, and abnormal cells.
• Removes dead or damaged cells.

Lymphatic System Functions

• Drains excess interstitial fluid.
• Transports dietary lipids.
• Carries out immune responses.

Purpose of Lymphatic Vessels

• Collect and filter lymph (fluid containing white blood cells).
  • Different from blood capillaries: Lymphatic capillaries are closed-ended and more permeable.
  • Most similar to lymphatic vessels: Veins, due to their thin walls and valves.

Mechanisms of Lymph Movement

• Skeletal muscle contractions.
• Respiratory movements (pressure changes during breathing).
• Valves within lymphatic vessels (prevent backflow).

Drainage Areas of Lymphatic Ducts

• Right lymphatic duct: Drains the upper right side of the body (right arm, right side of head and thorax).
• Thoracic duct: Drains the rest of the body.

Primary Lymphatic Organs

• Red bone marrow.
• Thymus.

Non-Encapsulated Lymphatic Tissue

• Mucosa-associated lymphoid tissue (MALT).
  • In the digestive tract: Gut-associated lymphoid tissue (GALT).

Three Tonsils

• Pharyngeal (adenoid).
• Palatine.
• Lingual.

Lymph Flow Through a Lymph Node

• Afferent lymphatic vessels → subcapsular sinus → trabecular sinuses → medullary sinuses → efferent lymphatic vessels.
  • Areas of proliferating lymphocytes: Lymphoid follicles/nodules.

Superficial Lymph Node Locations

• Axillary: Armpit.
• Cervical: Neck.
• Submandibular: Under the jaw.
• Inguinal: Groin.

Deep Lymphatic Structure Locations

• Cisterna chyli: Base of the thoracic duct in the abdomen.
• Iliac: Along the iliac blood vessels in the pelvis.
• Peyer’s patches: Small intestine (ileum).
• Bronchiomediastinal: Thorax, near bronchi and mediastinum.

Spleen Location

• Upper left quadrant of the abdomen.

White Pulp vs. Red Pulp in the Spleen

• White pulp: Lymphatic tissue, lymphocytes for immune function.
• Red pulp: Blood-filled sinuses and splenic cords for filtering blood.
  • Splenic cords: Made of reticular connective tissue, macrophages, and blood cells; filter blood and remove damaged cells.

Spleen Functions

• Filters blood.
• Stores platelets and monocytes.
• Site of lymphocyte proliferation and immune response.
• Removes aged or damaged blood cells.

Thymus Purpose

• Site of T cell maturation and selection.

Thymus Location

• Mediastinum, behind the sternum.

Innate vs. Adaptive Immune System

• Innate: Rapid, non-specific response; present from birth.
• Adaptive: Slower, specific response; develops over time with exposure.

Cells of Innate vs. Adaptive Immune System

• Innate: Natural killer cells, macrophages, neutrophils, eosinophils, basophils, mast cells.
• Adaptive: B cells and T cells.

Physical Barriers Preventing Microbe Entry

• Skin.
• Mucous membranes.

Molecular Motifs for Innate Immune System

• Pathogen-associated molecular patterns (PAMPs).
• Damage-associated molecular patterns (DAMPs).
• Microbial-associated molecular patterns (MAMPs).
  • Receptors: Pattern recognition receptors (PRRs), such as Toll-like receptors (TLRs).

Antigen-Presenting Cells (APCs)

• Cells that engulf antigens and present fragments of them on their surface to T cells, activating the adaptive immune response.

TLR Binding to a Pathogen

• Triggers intracellular signaling pathways.
• Leads to the production of cytokines and activation of immune cells.

Chemical Mediators

• Histamine: Promotes inflammation.
• Interferons: Antiviral proteins.
• Complement: Enhances phagocytosis, inflammation, and cell lysis.
• Lysozymes: Enzymes that break down bacterial cell walls.

White Blood Cell Movement and Destruction

• Chemotaxis: Movement toward a chemical signal.
• Phagocytosis: Engulfing and destroying pathogens.
• Diapedesis: Movement of white blood cells from blood vessels into tissues.

Blood Functions in Homeostasis

• Transports gases, nutrients, hormones, and waste products.
• Regulates pH (through buffers), body temperature, and fluid balance.
  • Blood helps regulate pH through buffers, which resist changes in pH.

Components of Blood

• Plasma (liquid portion).
• Formed elements: Red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes).

Components of Blood Plasma

• Water.
• Plasma proteins (albumin, globulins, fibrinogen).
• Nutrients, electrolytes, hormones, gases, and waste products.

Major Plasma Proteins and Their Functions

• Albumin: Maintains osmotic pressure.
• Globulins: Antibodies and transport proteins.
• Fibrinogen: Blood clotting.

Origin and Production of Blood Cells

• Hematopoiesis: Occurs in red bone marrow.
  • Myeloid progenitor cells: Give rise to red blood cells, platelets, and most white blood cells.
  • Lymphoid progenitor cells: Give rise to lymphocytes.
  • Hemocytoblast: Cell makes myeloid and lymphoid stem cells

Functions of Blood Cells

• Red blood cells: Transport oxygen and carbon dioxide.
• White blood cells: Immune response.
• Platelets: Blood clotting.

Hemoglobin Structure and Function

• Structure: Four polypeptide chains (globins), each with a heme group containing iron.
• Function: Binds and transports oxygen, carbon dioxide, and nitric oxide.
  • NO: Vasodilator.
  • CO2: Waste product.
  • O2: Essential for cell functions.

Life Cycle of Red Blood Cells

• Live for about 120 days.
  • Recycled: Iron and globin are recycled.
  • Eliminated: Heme is converted to bilirubin and excreted in bile.

White Blood Cell Types: Structure and Function

• Neutrophils: Phagocytosis of bacteria.
• Eosinophils: Kill parasitic worms; involved in allergic reactions.
• Basophils: Release histamine and heparin; involved in inflammation.
• Lymphocytes: Adaptive immunity (B cells, T cells).
• Monocytes: Phagocytosis; develop into macrophages in tissues.
  • (Be able to identify histologically)

Origin and Structure of Platelets

• Origin: Megakaryocytes in bone marrow.
• Structure: Cell fragments with granules.

Platelet Functions in Preventing Blood Loss

• Form platelet plug.
• Release factors that promote vasoconstriction and blood clotting.

Hemostasis Processes

• Vascular spasm: Constriction of damaged blood vessels.
• Platelet plug formation: Platelets adhere to damaged vessel and aggregate.
• Coagulation: Formation of a blood clot through a cascade of clotting factors.

Regulation and Removal of Clots

• Anticoagulants: Inhibit clot formation (e.g., heparin, antithrombin).
• Fibrinolysis: Breakdown of the clot by plasmin.

ABO Blood Group System

• Based on the presence or absence of A and B antigens on red blood cells.

Incompatibilities in ABO Blood Group

• Transfusion reactions can occur if the recipient has antibodies against the donor's red blood cell antigens.

Rh Blood Group

• Based on the presence or absence of the Rh (D) antigen.
  • Anti-D on a blood typing test indicates Rh-negative.
  • Type blood as A, B, AB, or O
  • Type blood as + or – (Rh factor)

MHC Molecules

• Display antigens to T cells.
  • MHC I: Present on all nucleated cells; present intracellular antigens to cytotoxic T cells (T killer cells).
  • MHC II: Present on antigen-presenting cells (APCs); present extracellular antigens to helper T cells.

Types of T Cells and Their Roles

• Treg (Regulatory T cells): Suppress immune response.
• Thelper (Helper T cells): Activate other immune cells, including B cells and cytotoxic T cells.
• Tkiller (Cytotoxic T cells): Kill infected or cancerous cells.

B Cells in Adaptive Immunity

• Produce antibodies that bind to antigens, neutralizing them or marking them for destruction.

Classes of Antibodies

• IgG: Most abundant; crosses the placenta; provides long-term immunity.
• IgM: First antibody produced during an infection; activates complement.
• IgA: Found in mucous membranes, saliva, and breast milk; provides localized protection.

Antibody Structure

• Variable region: Binds to specific antigen.
• Constant region: Determines antibody class and function.
• Light chain.
• Heavy chain.

Antibody Binding to Antigen

• When antibodies bind antigen, they clump or create a precipitate
• This is the agglutination seen in blood typing

Activated Complement Proteins

• Enhance inflammation.
• Promote opsonization (enhancing phagocytosis).
• Cause cell lysis.

Interferons

• Interfere with viral replication.
• Activate immune cells.

Organs of the Digestive Tract

• Mouth, pharynx, esophagus, stomach, small intestine, large intestine, anus.

Digestive Tract Functions

• Ingestion, secretion, mixing and propulsion, digestion, absorption, defecation.

Digestive vs. Accessory Organs

• Digestive: Organs forming the continuous tube from mouth to anus.
• Accessory: Teeth, tongue, salivary glands, liver, gallbladder, pancreas.

Serous Layers of Peritoneum

• Parietal peritoneum: Lines the abdominal wall.
• Visceral peritoneum: Covers the organs.

Intraperitoneal vs. Retroperitoneal Organs

• Intraperitoneal: Organs surrounded by peritoneum.
• Retroperitoneal: Organs behind the peritoneum (mnemonic: SAD PUCKER - Suprarenal glands, Aorta/IVC, Duodenum (parts), Pancreas (except tail), Ureters, Colon (ascending & descending), Kidneys, Esophagus, Rectum).

Mesentery

• Double layer of peritoneum that supports and suspends organs.
  • Conduit for: Blood vessels, nerves, and lymphatic vessels.

Peritoneal Ligaments

• Folds of peritoneum that support organs.
  • Lesser omentum: Connects the stomach and duodenum to the liver.
  • Greater omentum: Hangs from the stomach and covers the intestines.

Structures in the Lesser Omentum

• Hepatic artery, portal vein, and bile duct.

Peritoneal Recesses

• Females: Rectouterine pouch (pouch of Douglas).
• Males: Rectovesical pouch.

Mesentery Proper

• Connects the small intestine to the posterior abdominal wall

Peritonitis and Ascites

• Peritonitis: Inflammation of the peritoneum.
• Ascites: Accumulation of fluid in the peritoneal cavity.

Structures of Foregut

• Esophagus, stomach, liver, gallbladder, pancreas, and proximal duodenum.

Organs in Abdominal Quadrants

• Upper right: Liver, gallbladder.
• Upper left: Spleen, stomach.
• Lower right: Appendix, cecum.
• Lower left: Sigmoid colon.

Esophagus

• Muscular tube connecting the pharynx to the stomach.
  • Muscle types: Skeletal (upper), mixed (middle), smooth (lower).

Z-Line

• Esophagogastric junction: Where the esophageal epithelium transitions to gastric epithelium

Sphincter Between Stomach and Esophagus

• Lower esophageal sphincter (cardiac sphincter).

Stomach Function and Regions

• Function: Mixes food with gastric juice, starts protein digestion, absorbs some substances.
  • Cardia.
  • Fundus.
  • Body.
  • Pylorus.
  • Sphincters (lower esophageal, pyloric).
  • Curvatures (greater, lesser).
  • Mucosa.
  • Rugae.

Parts of the Duodenum

• Superior, descending, horizontal, ascending.

Segments of the Small Intestine

• Duodenum, jejunum, ileum (in order).

Liver Lobes

• Right.
• Left.
• Caudate.
• Quadrate.
  • Lobes: The quadrate lobe touches the gall bladder, the caudate touches the Inferior Vena Cava

Purpose of Bile

• Emulsifies fats for digestion and absorption.

Ligaments of the Liver

• Round ligament (ligamentum teres).
• Falciform ligament.
• Coronary ligament.

Components of Portal Triad

• Hepatic artery, portal vein, bile duct.

Venous Blood Flow Through Liver

• Portal vein → liver sinusoids → central vein → hepatic vein → inferior vena cava.

Ducts of the Bile System

• Proper hepatic duct.
• Cystic duct.
• Bile duct (common bile duct).

Major Duodenal Papilla

• Opening where the common bile duct and pancreatic duct enter the duodenum.

Cholecystitis

• Inflammation of the gallbladder.
  • Dangerous if a stone is lodged at the major duodenal papilla: Can cause pancreatitis and block bile flow.

Pancreas Parts

• Head, neck, body, tail.

Pancreas Cells and Enzymes

• Islet cells: Endocrine cells; produce hormones (insulin, glucagon, somatostatin).
• Acinar cells: Exocrine cells; produce digestive enzymes (amylase, lipase, protease).

Spleen Functions (Again)

• Filters blood, stores platelets, immune functions.

Spleen Location (Again)

• Upper left quadrant of the abdomen.

Valve Between Small and Large Intestine

• Ileocecal valve.

Features of the Large Intestine

• Omental appendices: Fat-filled pouches.
• Teniae coli: Longitudinal muscle bands.
• Haustra: Pouches caused by teniae coli.

Segments of the Large Intestine

• Cecum, ascending colon, transverse colon, descending colon, sigmoid colon, rectum, anal canal.

Vermiform Appendix

• Located at the cecum.

Colic Flexures

• Right colic flexure (hepatic flexure): Between ascending and transverse colon.
• Left colic flexure (splenic flexure): Between transverse and descending colon.

Retroperitoneal Colon

• Ascending and descending colon.

Line Separating Sensory in Anal Canal

• Pectinate line (dentate line).

Anal Sphincters

• Internal anal sphincter: Involuntary control (smooth muscle).
• External anal sphincter: Voluntary control (skeletal muscle).

Boundaries of Oral Cavity Proper

• Teeth and gums.

Location of Oral Vestibule

• Space between the teeth/gums and the cheeks/lips.

Circular Muscle Deep to Lips

• Orbicularis oris. Helps with pursing lips.

Labial Frenulum

• Connects the lips to the gums (maxillary and mandibular).
  • Lingual frenulum: Connects the tongue to the floor of the mouth.

Buccinator Muscle

• Located in the cheek. Compresses the cheek.

Hard Palate, Soft Palate, Uvula, and Fauces

• Hard palate: Bony anterior part of the roof of the mouth.
• Soft palate: Muscular posterior part of the roof of the mouth.
• Uvula: Projection hanging from the soft palate.
• Fauces: Opening between the oral cavity and pharynx.

Tonsil Locations

• Palatine: Lateral walls of the oropharynx.
• Lingual: Base of the tongue.
• Pharyngeal (adenoid): Posterior wall of the nasopharynx.

Papillae

• Filiform: Conical; provide texture but no taste buds.
• Fungiform: Mushroom-shaped; contain taste buds.
• Foliate: Ridges on the lateral edges of the tongue; contain taste buds.
• Circumvallate: Large, round; contain taste buds.

Tongue Innervation

• Anterior 2/3:
  • Special sensory (taste): Facial nerve (CN VII) via chorda tympani.
  • General sensory (touch): Trigeminal nerve (CN V3).
• Posterior 1/3:
  • Special and general sensory: Glossopharyngeal nerve (CN IX).

Types and Numbers of Teeth

• Incisors: 2 (mandibular and maxillary)
• Canines: 1 (mandibular and maxillary)
• Premolars: 2 (mandibular and maxillary)
• Molars: 3 (mandibular and maxillary)

Tooth Characteristics

• Crown: Visible part of the tooth.
• Root: Part of the tooth embedded in the bone.
• Enamel: Hard outer layer of the crown.
• Dentin: Primary material forming the tooth.
• Pulp cavity: Contains blood vessels and nerves.
• Gingiva: Gum tissue.

Neurovasculature Entry into Tooth

• Apical foramen.

Mastication

• Chewing.

Muscles of Mastication

• Masseter: Elevates and protracts mandible.
• Temporalis: Elevates and retracts mandible.
• Medial pterygoid: Elevates and protracts mandible.
• Lateral pterygoid: Depresses and protracts mandible.
  • Protraction: Moving jaw forward.
  • Retraction: Moving jaw backward.

Salivary Glands

• Parotid: Located near the ear.
• Submandibular: Located under the mandible.
• Sublingual: Located under the tongue.
  • Parotid: Does the majority of secretions

Digestive Enzymes in Saliva

• Salivary amylase: Digests carbohydrates.
• Lingual lipase: Digests fats.

Muscles of the Floor of the Oral Cavity

• Mylohyoid.
• Geniohyoid.

Innervation and Blood Supply of Teeth

• Maxillary teeth: Maxillary nerve and artery.
• Mandibular teeth: Inferior alveolar nerve and artery.

Regions of the Pharynx

• Nasopharynx.
• Oropharynx.
• Laryngopharynx.

Auditory Tube in Nasopharynx

• Connects the nasopharynx to the middle ear. Equalizes pressure.

Layers of the GI Tract

• Mucosa: Innermost layer; epithelium, lamina propria, muscularis mucosae.
• Submucosa: Connective tissue layer with blood vessels, nerves, and lymphatics.
• Muscularis externa: Two muscle layers (circular and longitudinal) for peristalsis.
• Serosa/Adventitia: Outermost layer; serosa (peritoneum) in abdominal cavity, adventitia (connective tissue) in esophagus.

Muscularis Externa

• Two muscular layers: Circular and longitudinal.
• Plexus: Myenteric plexus (Auerbach's plexus) controls peristalsis.

Enteric Nervous System

• Intrinsic nervous system of the GI tract.
  • Two plexuses: Submucosal plexus (Meissner's plexus) controls secretions, myenteric plexus controls motility.
  • Channel of Communication: Autonomic nervous system (sympathetic and parasympathetic).

Function of Saliva

• Moistens food, begins chemical digestion, cleanses mouth.

Components of Saliva

• Water, electrolytes, mucus, enzymes (amylase, lipase), antibacterial compounds.

Salivary Glands (Again)

• Parotid, submandibular, sublingual.
  • The parotid glands contribute the most to saliva production

Salivary System Innervation

• Sympathetic: Decreases salivation (dry mouth).
• Parasympathetic: Increases salivation (watery saliva).

Saliva's Protective Properties

• Lysozyme and IgA antibodies inhibit bacterial growth.

Phases of Swallowing

• Voluntary (buccal) phase: Tongue pushes food bolus into oropharynx.
• Pharyngeal phase: Swallowing reflex; epiglottis closes over larynx.
• Esophageal phase: Peristalsis moves bolus down the esophagus.

Hunger-Regulating Hormones

• Ghrelin: Increases hunger (released by stomach).
• Leptin: Decreases hunger (released by adipose tissue).

Stomach Layers

• Mucosa, submucosa, muscularis externa, serosa.
  • Difference in Muscularis: Has three layers (inner oblique, middle circular, outer longitudinal).

Gastric Cells

• Mucous cells: Secrete mucus.
• Parietal cells: Secrete HCl and intrinsic factor.
• Chief cells: Secrete pepsinogen and gastric lipase.
• Enteroendocrine cells (G cells): Secrete gastrin.
• Stem Cells: Replace damaged cells

Function of HCl in Stomach

• Denatures proteins, activates pepsinogen, kills bacteria.
  • Produced by parietal cells from H+ and Cl– ions

Function of Mucus in Stomach

• Protects stomach lining from acid and enzymes.
  • Produced by mucous cells.
  • Lack of mucus leads to ulcers.

Function of Pepsinogen and Gastric Lipase

• Pepsinogen: Converted to pepsin for protein digestion.
• Gastric lipase: Digests fats.

Parasympathetic Stimulation in Stomach

• Stimulates parietal cells (HCl and intrinsic factor), chief cells (pepsinogen), mucous cells (mucus), and G cells (gastrin).

Stomach Distention Triggers

• Parasympathetic (vagus nerve) activity.

Chyme in Duodenum Triggers

• Secretin: Stimulates bicarbonate secretion from pancreas.
• Cholecystokinin (CCK): Stimulates bile release from gallbladder and enzyme secretion from pancreas.

Small Intestine Surface Area

• Circular folds (plicae circulares).
• Villi.
• Microvilli.
  • Lacteal: Lymphatic structure found in the villi
    • Chyle: The fluid in the lacteal

Major GI Hormones

• Table 24.1: Review secretion, stimulation, and motility effects of gastrin, secretin, and CCK.

Venous Flow Through Liver

• Sinusoids drain into central vein.

Liver Macrophages

• Kupffer cells.

Liver Cells

• Hepatocytes.
  • Functions: Making bile, taking up nutrients from portal blood, detoxifying, storing or synthesizing new compounds.

Mesenteric Veins

• Superior mesenteric vein drains into portal vein.
• Inferior mesenteric vein drains into splenic vein, which drains into portal vein.

Purpose of Bile Salts

• Emulsify fats.

Micelles

• Clusters of bile salts and digested lipids.

Bile Salt Reabsorption

• Ileum.

Pancreatic Enzymes

• Amylase, lipase, proteases, nucleases.

Pancreatic Hormones

• Insulin, glucagon, somatostatin.

• tin.

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