DIGESTIVE. CHAPTER 17 Lecture: Part 1 Part 2 BIO 212: ANATOMY & PHYSIOLOGY II

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1 BIO 212: ANATOMY & PHYSIOLOGY II 1 CHAPTER 17 Lecture: DIGESTIVE Part 1 Part 2 Dr. Lawrence G. Altman Some illustrations are courtesy of McGraw-Hill.

2 Processes of DIGESTION Mechanical and Chemical Reductions of Foodstuffs INGESTION intake of food into mouth 02. MASTICATION pulverizing food (chewing) starch breakdown (amylase from saliva) 03. DEGLUTITION swallowing

3 Processes of DIGESTION Mechanical and Chemical Reductions of Foodstuffs PERISTALSIS rhythmic, wavelike contractions move food through tubular alimentary canal (GI tract) 05. ABSORPTION generally, passage of reduced food molecules through mucous membranes of small intestine To blood and/or lymphatics > cells 06. DEFECATION Discharge of indigestible waste (feces)

4 Accessory Organs Alimentary Canal 4

TONGUE; Taste Buds Taste Buds found on Projections: Papillae 5 CIRCUMVALLATE Papillae:

moat around castle Respond to: Bitter Lingual Tonsil FILIFORM Papillae: Conical shaped

No Taste Buds Roughness of tongue Most Numerous; keratin; White of tongue.

5 TONGUE; Taste Buds Taste Buds found on Projections: Papillae 5 CIRCUMVALLATE Papillae: Arranged in a V- shaped row. moat around castle Respond to: Bitter Lingual Tonsil FILIFORM Papillae: Conical shaped Parallel Rows. No Taste Buds Roughness of tongue Most Numerous; keratin; White of tongue. Circumvallate Papilla FUNGIFORM Papillae: Fungus shaped; Anterior 2/3 of tongue. Respond to: Sweet, salt and sour DIFFICULT to SEE in SEM- - - HIST PHOTO better. Lingual frenulum Underside; mucous membrane attachment Filiform Papilla

6 6 Conical FILIFORM PAPILLAE Fungi - shaped FUNGIFORM PAPILLA Moat around Castle CIRCUMVALLATE PAPILLA EACH PAPILLA may give rise to DOZENS of TASTE BUDS LAB ATLAS EQUIVALENT: FIGS. 72 A - B - C

SALIVARY GLANDS: Merocrine (secretory vesicles; exocytosis EXOCRINE GLANDS:

Carbohydrates) MUCOUS CELLS- viscous mucus fluid MYOEPITHELIAL CELLS- surround

7 SALIVARY GLANDS: Merocrine (secretory vesicles; exocytosis EXOCRINE GLANDS: SECRETIONS VIA DUCTS (ENDOCRINE: DIRECTLY INTO BLOOD) ACINI (rounded sacs): contained in gland at end of ducts. EPITHELIUM of ACINI: SEROUS CELLS- watery fluid + AMALASE (vs. Carbohydrates) MUCOUS CELLS- viscous mucus fluid MYOEPITHELIAL CELLS- surround acini/ducts; mini- pumps 7 - tongue- PAROTID GLAND PAROTID duct Masseter Muscle SUBMANDIBULAR GLAND Cut; duct Buccinator Muscle VESTIBULE SUBLINGUAL GLAND

HUMAN SUBMANDIBULAR GLAND ACINI (rounded sacs): contained in gland at end of ducts. EPITHELIUM of ACINI: FLOOR of MOUTH NEAR LOWER JAW SEROUS CELLS- watery fluid + AMALASE (vs.

8 HUMAN SUBMANDIBULAR GLAND ACINI (rounded sacs): contained in gland at end of ducts. EPITHELIUM of ACINI: FLOOR of MOUTH NEAR LOWER JAW SEROUS CELLS- watery fluid + AMALASE (vs. Carbohydrates) MUCOUS CELLS- viscous mucus fluid MYOEPITHELIAL CELLS- surround acini/ducts; mini- pumps MOSTLY SEROUS CELLS SEROUS CELLS 8 Hematoxylin- aniline Blue SECRETORY DUCT SEROUS CELL MUCOUS CELL MIXED ALVEOLUS SALIVA: mixture of all Three (3) Salivary Glands. Lysozyme, IgA, and mucus- bolus formation.

9 SALIVARY GLANDS: Merocrine (secretory vesicles; exocytosis) 9

10 TEETH; Deciduous (baby, milk) 10 First complete set; erupt approx. 6 months. Lower central incisors- first to erupt. Full set (20) usually complete by age of two. Eventual loss (loosening) due to reabsorption of roots. All of the second or "permanent" set (except third molars) have usually erupted by end of adolescence.

TEETH; Permanent (adult, second set) FOUR (4) QUADRANTS; Upper & lower (left + right) = 32 8 teeth per Quadrant Numbers are for EACH quadrant 11 2 INCISORS (cutting) CENTRAL

11 TEETH; Permanent (adult, second set) FOUR (4) QUADRANTS; Upper & lower (left + right) = 32 8 teeth per Quadrant Numbers are for EACH quadrant 11 2 INCISORS (cutting) CENTRAL INCISOR 1 CANINE - cuspid- (tearing) 2 PREMOLARS - bicuspid- (grinding) 3 MOLARS - tricuspid- (grinding) Lower right M3 a Wisdom Tooth. M2 M1 Can you determine which tooth is missing?

12 12

TEETH; (molar shown but structures same for all) 13 A B C BONE ENAMEL: hardest substance in body covers crown; ^calcium phosphate DENTIN: bone- like; most of tooth PULP CAVITY: GINGIVA: gum contains

13 TEETH; (molar shown but structures same for all) 13 A B C BONE ENAMEL: hardest substance in body covers crown; ^calcium phosphate DENTIN: bone- like; most of tooth PULP CAVITY: GINGIVA: gum contains nerves and blood and lymph vessels PERIODONTAL MEMBRANE (ligament): fibrous ligament lines socket; anchors tooth CEMENTUM: thin adhesive layer between tooth and periodontal ligament ROOT CANAL BLOOD VESSELS and NERVES in Pulp A=CROWN, B=NECK, C=ROOT APICAL FORAMEN (opening) MP LAB ATLAS: Fig. 74- C

DIGESTIVE TRACT: Generalized Histology 1. MUCOSA 2. SUBMUCOSA Lamina Propria Epithelium Muscularis Lumen mucosae (THIN) SUBMUCOSA (loose CT) conducts large BV, Lymphatics, Nerves.

14 DIGESTIVE TRACT: Generalized Histology 1. MUCOSA 2. SUBMUCOSA Lamina Propria Epithelium Muscularis Lumen mucosae (THIN) SUBMUCOSA (loose CT) conducts large BV, Lymphatics, Nerves. LOCAL CONTROL: MEISSNER'S PLEXUS 3. MUSCULARIS EXT. 2 (+) smooth muscle layers: INNER: circular OUTER: longitudinal Myenteric (Auerbach's) plexus Both: Basis of PERISTALSIS 4. ADVENTITIA outer Connective tissue; conducts major Blood Vessels and Nerves. If exposed to Abdominal Cavity, called: SEROSA & lined with Simple Squamous Epithelium (MESOTHELIUM) 14

15 15

16 16

17 ESOPHAGEAL/GASTRIC JUNCTION Cardiac Region of Stomach 17 NOTE: Abrupt change from protective Stratified Squamous Epith. to Highly Glandular Simple columnar Epith. INCREASED TONE of MUSCULARIS EXTERNA forms a "Physiological" Sphincter; prevents reflux of gastric contents. LOW MAG X 20 X 128 MP LAB ATLAS: Fig. 77- C

18 Greater Omentum 18

19 STOMACH 19 (Cardiac sphincter) often contains swallowed air Lesser Curvature - folds Greater Curvature

20 MUSCLE LAYERS of the STOMACH 20 MUSCULARIS EXTERNA Usually contains two layers along Digestive Tract. In STOMACH: THREE (3) layers. Innermost layer- oblique muscle. Circular layer (middle) Longitudinal layer (outermost)

21 21 RUGAE in STOMACH GROSS VIEW SCANNING ELECTRON MICROSCOPY (SEM)

22 22

STOMACH MUCOSA ph in stomach: 1.5-3.0!!! Gastric Pits leading to Gastric Glands.

23 STOMACH MUCOSA ph in stomach: !!! Gastric Pits leading to Gastric Glands. (SEM) GASTRIN: a hormone produced by cells in the pyloric region which increases the secretory output of gastric glands SOMATOSTATIN: a hormone produced by some cells in the stomach which decreases the secretory output of gastric glands 23

24 STOMACH HISTOLOGY 24 MOST of the Stomach is highly GLANDULAR.

25 SIMPLE COLUMNAR EPITHELIUM ALSO see TABLE 17.5 GASTRIC GLAND STOMACH Small INTESTINE CHYME = FOOD + GASTRIC JUICES NECK MUCOUS CELLS PARIETAL CELLS CHIEF CELLS LAMINA PROPRIA MUSCULARIS MUCOSA GASTRIC JUICE NECK = MUCOUS CELLS + GOBLET CELLS both produce types of MUCUS; viscous and alkaline- some protection to mucosa PARIETAL (Oxyntic) CELLS- INTRINSIC FACTOR : (aids in B- 12 absorption) HCl : (inhibited by somatostatin) a) kills pathogens b) required for conversion: pepsinogen - - > pepsin CHIEF CELLS (Zymogenic)- Secrete PEPSINOGEN (inactive form of pepsin): Pepsin is a protein - splitting enzyme. 25

26 26 Last Slide: DIGESTIVE SYSTEM 1 of 2

The Digestive System. Chapter 25

The Digestive System. Chapter 25 The Digestive System Chapter 25 Introduction Structure of the digestive system A tube that extends from mouth to anus Accessory organs are attached Functions include Ingestion Movement Digestion Absorption