Ch17a DIGESTION; Dr. L. Altman · 2020. 12. 23. · ANATOMY & PHYSIOLOGY II BIO 212: Dr. Lawrence...
Transcript of Ch17a DIGESTION; Dr. L. Altman · 2020. 12. 23. · ANATOMY & PHYSIOLOGY II BIO 212: Dr. Lawrence...
ANATOMY & PHYSIOLOGY II BIO 212:
Dr. Lawrence G. Altman www.lawrencegaltman.com Some illustrations are courtesy of McGraw-Hill.
CHAPTER 17 Lecture:
DIGESTIVE
Part 1 Part 2
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Processes of DIGESTION
Mechanical and Chemical Reductions of Foodstuffs
01. INGESTION intake of food into mouth
02. MASTICATION pulverizing food (chewing) starch breakdown (amylase from saliva)
DEGLUTITION swallowing
03.
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04. 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. Discharge of indigestible waste (feces) DEFECATION
Processes of DIGESTION
Mechanical and Chemical Reductions of Foodstuffs
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Accessory Organs Alimentary Canal 4
TONGUE; Taste Buds Taste Buds found on Projections: Papillae
Circumvallate Papilla
CIRCUMVALLATE Papillae: Arranged in a V-‐ shaped row.
“moat around castle” Respond to: Bitter
Filiform Papilla
FILIFORM Papillae: Conical – shaped
Parallel Rows. No Taste Buds Roughness of tongue
Most Numerous; keratin; White of tongue.
DIFFICULT to SEE in SEM-‐-‐-‐ HIST PHOTO better.
FUNGIFORM Papillae: Fungus – shaped;
Anterior 2/3 of tongue. Respond to:
Sweet, salt and sour Lingual frenulum
Underside; mucous membrane attachment
Lingual Tonsil
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FILIFORM PAPILLAE
FUNGIFORM PAPILLA
CIRCUMVALLATE PAPILLA
EACH PAPILLA may give rise to DOZENS of TASTE BUDS
“Moat around Castle” Fungi -‐ shaped Conical
LAB ATLAS EQUIVALENT: FIGS. 72 A -‐ B -‐ C
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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.
Buccinator Muscle
Masseter Muscle VESTIBULE
PAROTID GLAND
PAROTID duct
SUBMANDIBULAR GLAND Cut; duct
-‐tongue-‐
SUBLINGUAL GLAND
EPITHELIUM of ACINI: SEROUS CELLS-‐ watery fluid + AMYLASE (vs. Carbohydrates) MUCOUS CELLS-‐ viscous mucus fluid MYOEPITHELIAL CELLS-‐ surround acini/ducts; mini-‐pumps
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HUMAN SUBMANDIBULAR GLAND FLOOR of MOUTH NEAR LOWER JAW
Hematoxylin-‐aniline Blue
MOSTLY SEROUS CELLS SEROUS CELLS
SEROUS CELL MUCOUS CELL
SECRETORY DUCT
MIXED ALVEOLUS
EPITHELIUM of ACINI: SEROUS CELLS-‐ watery fluid + AMYLASE (vs. Carbohydrates) MUCOUS CELLS-‐ viscous mucus fluid MYOEPITHELIAL CELLS-‐ surround acini/ducts; mini-‐pumps
ACINI (rounded sacs): contained in gland at end of ducts.
SALIVA: mixture of all Three (3) Salivary Glands. Lysozyme, IgA, and mucus-‐ bolus formation.
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SALIVARY GLANDS: Merocrine (secretory vesicles; exocytosis) 9
TEETH; Deciduous (baby, milk)
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.
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TEETH; Permanent (adult, second set) FOUR (4) QUADRANTS; Upper & lower (left + right) = 32 8 teeth per Quadrant
2 INCISORS (cutting)
Numbers are for EACH quadrant
1 CANINE -‐cuspid-‐ (tearing)
2 PREMOLARS -‐bicuspid-‐ (grinding)
3 MOLARS -‐tricuspid-‐ (grinding)
Can you determine which tooth is missing? Lower right M3
a Wisdom Tooth.
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M1
CENTRAL INCISOR
M2
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TEETH; (molar shown but structures same for all)
BONE
MP LAB ATLAS: Fig. 74-‐C
A
B
C
A=CROWN, B=NECK, C=ROOT
ENAMEL: hardest substance in body covers crown; ^calcium phosphate DENTIN: bone-‐like; most of tooth PULP CAVITY:
BLOOD VESSELS and NERVES in Pulp ROOT CANAL
APICAL FORAMEN (opening)
GINGIVA: gum
PERIODONTAL MEMBRANE (ligament): fibrous ligament lines socket; anchors tooth CEMENTUM: thin adhesive layer between tooth and periodontal ligament
contains nerves and blood and lymph vessels
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Lumen Epithelium
Lamina Propria
√
Muscularis mucosae (THIN)
√
SUBMUCOSA (loose CT) conducts large BV, Lymphatics, Nerves.
DIGESTIVE TRACT: Generalized Histology 1. MUCOSA √
√ 2. SUBMUCOSA
LOCAL CONTROL: MEISSNER'S
PLEXUS
3. MUSCULARIS EXT. 2 (+) smooth muscle layers: INNER: circular
OUTER: longitudinal
Both: Basis of PERISTALSIS
Myenteric (Auerbach's) plexus
4. ADVENTITIA
outer Connective tissue; conducts major Blood Vessels and Nerves. If exposed to Abdominal Cavity, called: SEROSA & lined with Simple Squamous Epithelium (MESOTHELIUM)
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ESOPHAGEAL/GASTRIC JUNCTION
LOW MAG X 20 X 128
Cardiac Region of Stomach
MP LAB ATLAS: Fig. 77-‐C
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.
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Greater Omentum 18
STOMACH
(Cardiac sphincter)
Greater Curvature
Lesser Curvature
-‐ folds
often contains swallowed air
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MUSCLE LAYERS of the STOMACH
MUSCULARIS
EXTERNA
Usually contains two
layers along Digestive Tract.
In STOMACH: THREE (3) layers. Innermost layer-‐ oblique muscle.
Circular layer (middle)
Longitudinal layer (outermost)
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GROSS VIEW
RUGAE
in STOMACH
SCANNING ELECTRON MICROSCOPY
(SEM)
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MOST of the Stomach is highly GLANDULAR.
STOMACH HISTOLOGY
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STOMACH
MUCOSA
Gastric
Pits
leading to
Gastric
Glands. (SEM)
pH in stomach: 1.5 -‐ 3.0 !!!
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
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SIMPLE COLUMNAR EPITHELIUM
GASTRIC GLAND
NECK CELLS
CELLS
CHIEF CELLS
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.
CHYME = FOOD + GASTRIC JUICES
STOMACH Small
INTESTINE
ALSO see TABLE 17.5
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LAMINA PROPRIA MUSCULARIS MUCOSA
PARIETAL
MUCOUS
DIGESTIVE SYSTEM 1 of 2
Last Slide:
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