Anatomy & Physiology II BIOS 2320 Instructor: Mrs. Sarah Jeffers

Introduction Syllabus Typical schedule with resources Student Helpful websites: “Student edition” link

Unit I: Metabolism Digestive System Part I Chapter 21

Digestive system Nutrients Tissue cells Wastes Urinary system Cardio- vascular system O 2 and CO 2 Cardiopulmonary system Metabolism multiple changes in the molecules of the food we eat. Digestive System: primary purpose – to break food down into forms that can be used by the body and to absorb them so they can be distributed to the tissues.

Digestive Processes Motility Secretion Membrane transport

Digestive Functions 1.Ingestion 2.Digestion Mechanical Chemical 3.Absorption 4.Compaction 5.Defecation

Stages of Digestion Mechanical digestion Chemical digestion a. enzymes –series of hydrolysis reactions that break macromolecules into their monomers (residues) –Results: Monosaccharides, amino acids, glycerol, fatty acids, and nucleotides Vitamins, minerals, cholesterol, & water are absorbed.

Mouth Oral cavity, teeth, tongue Pharynx Esophagus Stomach Small intestine Large intestine Anus Pancreas Gallbladder Liver Salivary glands Accessory Organs Anatomical Subdivisions of Digestive System Digestive tract –(Alimentary canal) –30 foot long tube –GI tract Accessory organs –salivary glands, teeth, tongue, liver, gallbladder, pancreas

Muscularis Externa Serosa Myenteric plexus Circular layer Longitudinal layer Mucosa Submucosa Lymphatic vessel Artery and vein Submucosal plexus Muscularis mucosae Lamina propria Villi Circular Folds Components of the Mucosa stratified squamous epithelium or simple columnar epithelium Tissue Layers Mucosa Submucosa Muscularis Externa Serosa/Adventitia

Mouth/Oral Cavity/Buccal Cavity Upper lip Tongue Lower lip Submandibular Sublingual Salivary glands: Palatine tonsil Hard palate and friction ridges Soft palate Uvula Palatopharyngeal arch Labial frenulum Vestibule Functions: Ingestion Taste Mechanical digestion Chemical digestion Swallowing Speech Respiration Stratified Squamous Skeletal Muscle

Superior Boundary Anterior and Lateral Boundary Nasal cavity Labium, or lip Cheek Body of the tongue Soft palateHard palate Pharyngeal tonsil Uvula Root of the tongue Lingual tonsil Palatine tonsil Inferior Boundary The geniohyoid and mylohyoid muscles supporting the floor of the mouth Posterior Boundary Boundaries of the Oral Cavity

Dentition Deciduous (20) by 3 years; Permenant (32) between 6 and 25 years Types of teeth: Incisors Canines/ Cuspids Premolars and molars/ Bicuspids

Salivary gland ductMucous cellsSerous cells Submandibular salivary glandLM x 600 Salivary Glands Small intrinsic glands found dispersed amid oral tissues, lips, cheeks and tongue - secrete at constant rate 3 pairs extrinsic glands connected to oral cavity by ducts –Parotid –Submandibular –Sublingual Sublingual Submandibular Parotid

Saliva Hypotonic solution of 99.5% water + solutes –Salivary amylase: begin starch digestion –Lingual lipase: fat digestion in stomach –Mucus: bind food together into bolus –Lysozyme: inhibit bacteria –Immunoglobin A: inhibit bacteria –Electrolytes (Na, K, Cl, phosphate, bicarbonate) pH

Pharynx Oropharynx Nasopharynx Laryngopharynx Pharynx: Vomer Muscular funnel 13 cm long Skeletal muscle –deep layer – –superficial layer - Superior middle inferior (UES) Stratified squamous

Esophagus Straight muscular tube cm long Extends from pharynx to cardiac stomach passing through esophageal hiatus in diaphragm –Cardiac orifice –Lower esophageal sphincter (LES)

Why do you think acid causes such problems for people when acid is actually a natural product found in the digestive system? i.e. How does the stomach tolerate such acidity?

Healthy Mucosa and Peptic Ulcer Helicobacter pylori

Stomach Mechanically breaks up food, liquifies food –chyme Does not absorb significant amount of nutrients –absorbs aspirin and some lipid-soluble drugs

Esophagus Lesser curvature The Pylorus Cardiac Fundus Body Layers of the Muscularis Externa Greater curvature Rugae Circular layer Oblique layer Longitudinal layer Anterior surface Pyloric sphincter Lesser curvature Esophagus Lesser omentum Liver Spleen Diaphragm Greater omentum Greater curvature Duodenum Pylorus Body Cardiac Fundus Stomach Regions Volume: 50ml – 4L Four regions Muscular sac Gross Anatomy of Stomach

Unique Features of Stomach Wall Mucosa –simple columnar glandular epithelium –Rugae / gastric pits Muscularis externae: 3 layers

Gastric Secretions 1.HCl Gastric glands contain carbonic anhydrase (CAH) Functions: Activates pepsin and lingual lipase Breaks up connective tissues and plant cell walls Converts iron to a usable form (Fe 2+ ) Destroys ingested bacteria and pathogens

2. Pepsin - –pepsinogen (inactive) + HCl  pepsin (active) –Chief cells 3. Gastric Lipase −Digests fats −Chief cells 4. Intrinsic factor –Essential for vitamin B 12 absorption –RBC production (lack causes pernicious anemia) –Parietal cells Gastric Secretions

Chemical Secretions 5. Chemical Messengers Many produced by G-cells –Ex.) gastrin, serotonin, histamine, somatostatin –hormones –paracrine secretions –Gut-brain peptides