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Digestive System Function: to obtain nutrients. Digestive System Function: obtaining nutrients. Activities of Digestion system: Ingestion – taking food or liquid into the mouth (eating or drinking). Movements Peristaltic and Segmentation Digestion Mechanical mastication

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slide1

Digestive System

Function:

to obtain nutrients

slide2

Digestive System

Function: obtaining nutrients

  • Activities of Digestion system:
    • Ingestion – taking food or liquid into the mouth (eating or drinking).
    • Movements
      • Peristaltic and Segmentation
    • Digestion
      • Mechanical
        • mastication
        • churning
      • Chemical
        • Enzymes and acids
    • Absorption – movement of substances into the body (across epithelium).
    • Elimination – involves compaction to eliminate waste from body
layers of gastrointestinal tract
Layers of Gastrointestinal Tract
  • Four layers:
    • Know layers and their composition
  • Tunic mucosa
    • Epithelial
    • Propria
    • Muscularis mucosae
  • Tunic submucosa
  • Tunica muscularis externa
  • Tunica serosa-visceral peritoneum
slide6

Tunic Mucosa

  • Lines digestive tract
  • Moistened by glandular secretions
  • Simple or stratified depending on area of tract
  • Pleated for expansion (Surface Area)
slide8

1. Tunic Mucosa

  • A Mucous membrane
    • 1) Epithelium
    • 2) Lamina propria
    • 3) Muscularis mucosae

2. Tunic Submucosa

  • Areolar Connective Tissue
  • Innervation
  • May have glands
slide9

Muscularis Mucosa

  • Smooth muscle layer capable of plasticity
    • Ability to tolerate stretching
  • Visceral smooth muscle
slide10

3. Tunica Muscularis Externa

  • Smooth muscle layers
  • 1) Inner Circular Layer
  • 2) Outer Longitudinal Layer

4. Tunica Serosa (or Adventitia*)

Serous membrane – visceral peritoneum

  • * Name depends on location:
  • Inside peritoneal cavity = serosa
  • Outside peritoneal cavity = adventitia
slide12

Serous Membranes

  • The Peritoneum: Two layers
    • Visceral peritoneum (a.k.a serosa)
    • Parietal peritoneum
      • Lines inner surfaces of body wall
  • Mesenteries: Fused double sheets of peritoneal membrane – to suspend portions of digestive tract:
    • Greater omentum
    • Lesser omentum
    • Mesentery proper
    • Transversemesocolon
    • Sigmoid mesocolon
slide13

Retroperitoneal Structures – these are attached to posterior abdominal wall

    • Ascending colon
    • Descending colon
    • Duodenum
    • Pancreas
salivary glands
Salivary glands
  • Parotid
  • Sublingual
  • Submandibular
    • Slightly different secretions
    • Release enzymes - amylase
    • Lubrication oral cavity
slide16

Fig

25.6

slide18

Fig

25.7

Only example of gomphosis joint

Incisors -clipping/cutting

Canines-tearing/slashing

Premolars- mashing/grinding

Molarsmashing/grinding

teeth
Teeth

Regions:

Crown

Neck

Root

Layers:

Enamel

Dentin

Pulp Cavity with Pulp

Cementum

Apical foramen

Root canal

Periodontal membrane

slide20

Voluntary control

Pharynx and Esophagus

Deglutition

Swallowing

Epiglottis closes over larynx

slide23

Tunica muscularis has three layers of muscle

Fig

25.11

Tunica mucosa has folds, rugae when empty

slide25

Histology of Gastric glands

Chief - Pepsinogen; Parietal - HCl; Neck/Mucous Cells

  • Secretin and cholecystokinin
    • Inhibit gastric secretion
slide26

Small Intestine

Duodenum

Jejunum

Ileum

Increase Surface Area for Absorption

Plicae Circulares

Intestinal villi

Microvilli

  • Lacteal (terminal lymphatic)
  • for lipid absorption
  • Intestinal glands
    • Goblet cells
    • Stem cells
slide28

Diagrammatic view highlighting the distinguishing features of each region of the small intestine.

slide29

Duodenum:

  • Duodenal (Brunner’s) glands produce:
        • secretin
        • CCK
        • Alkaline mucus
slide33

Large intestine

  • Functions of large intestine
    • Reabsorb water and compact feces
    • Absorb vitamins
    • Store fecal matter
  • Cecum
    • Ileocecal valve
    • Collects material from small intestine
    • Vermiform appendix
  • Colon - ascending, transverse, descending and sigmoid
  • Rectum
slide35

Histology of Large Intestine

Large Intestine:

Lack of villi

Abundance of goblet cells

Mucous-secreting intestinal glands

Muscularis reduced to Taenia coli

Fatty appendices

slide37

Other digestive organs

Horizontal section through the upper abdomen showing the position of the liver relative to other visceral organs.

pancreas2
Pancreas

Exocrine: acini

Endocrine:

Pancreatic islets

Isles of Langerhans

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