The Digestive System Organ groups of digestion Alimentary
- Slides: 48
The Digestive System
Organ groups of digestion • Alimentary organs – – – Mouth Pharynx Esophagus Stomach Small and large intestine • Accessory digestive organs – – – Teeth and tongue Liver Pancreas Salivary glands gallbladder
The processes of digestion • Ingestion • Secretion • Mixing and propulsion • Mechanical and chemical digestion • Absorption • Defecation
Peristalsis and segmentation • Peristalsis
Layers of the GI tract • Mucosa – Layer of epithelium – Lamina propria (connective tissue) – Thin layer of smooth muscle (muscularis mucosae) • Submucosa • Muscularis • Serosa
ANS input • Vagus nerve supplies parasympathetic input to most parts of the GI tract. • Preganglionic parasympathetic neurons synapse on postsynaptic neurons in the submucosal and myenteric plexuses. • Parasympathetic stimulation increases motility and GI secretion. • Sympathetic postsynaptic neurons in the plexuses decrease GI section and decrease motility by inhibiting neurons of ENS
Mouth • • Buccal cavity Oral mucosa Vestibule Gingivae Hardpalate Soft palate Uvula
• Cleanse mouth • Dissolve food chemicals • Moisten food • Enzymes break down carbs Salivary glands
Teeth • Crown, neck and root • Peridontal ligament • Enamel • Dentin • Root canal
Tooth varieties Incisors Cuspids Bicuspids Molars Mastication n Bolus
Tongue
Swallowing • Deglutition • 3 phases – Buccal – Pharyngeal – Esophogeal • Peristalsis – Secondary peristaltic waves
Deglutition
• Fundus • Body • Pylorus – Pyloric sphincter • Rugae Stomach
Stomach histology
Gastric Glands • Mucous cells – Surface & neck • G cells • Parietal cells • Chief cells • Enteroendocrine cells
Stomach and chemical digestion Cephalic (Reflex) phase – Triggered by sensory signals surrounding food. – Activates vagal nerve and ANS to enhance secretions – Hydrochloric Acid Production in Parietal Cells
Stomach and chemical digestion Gastric Phase – Activation of local myeteric reflexes and vagovagal reflexes – Gastrin – Release of HCl from parietal cells
Stomach and chemical digestion • Intestinal Phase – Excitatory component – Inhibitory component
Gastric Secretion: 3 Phases
Stomach and mechanical digestion • Stomach filling • Contractile activity – Peristalsis • Gastric emptying
Small intestine and associated organs
Small intestine histology
Small intestine histology
Liver • Digestive function is to produce bile. • Metabolic function is to process venous blood from digestive tract • Functional unit is a lobule
Liver
Liver Functions • • • Carbohydrate metabolism Lipid metabolism Protein metabolism Processing of drugs and hormones Excretion of bilirubin Synthesis of bile salts Storage Phagocytosis Activation of vitamin D
Cholesterol
Accessory organs
Bile • Alkaline solution that includes bile salts, phospholipids and electrolytes. – Bile salts derived from cholesterol • Bile salts emulsify fats and solubilize cholesterol, increasing absorption. • Bile is recycled • Fatty chyme and bile returning to liver stimulates more production of bile.
Gallbladder • The gallbladder stores and concentrates bile. • Bile release into duodenum 1. Fatty chyme stimulates release of CKK and secretin. 2. CKK enters bloodstream 3. Bile salts and secretin in the blood stimulate liver to rapidly produce bile. 4. Vagal stimulation leads to weak contractions. 5. CKK causes gallbladder to contract and
Pancreatic juice • Insulin & Glucose Regulation
Digestion in Small intestine: chemical • Digestion of carbohydrates – Pancreatic amylase – Brush-border enzymes • Digestion of proteins – Enzymes from pancreatic juice – Brush-border peptidases releases single AAs • Digestion of lipids – Digestion & Absorption of Fats • Digestion of nucleic acids
Digestion in Small intestine: mechanical • Segmentation leads to chyme being moved backwards and forwards. • Parasympathetic input increases intensity of contractions; sympathetic input decreases intensity. • Peristalsis occurs after nutrients are absorbed; regulated by motilin. – Migrating motility complex • Movement through ileocecal sphincter is enhanced by gastrin. • Once meal has passed through sphincter
Water • Water moves in both directions and follows flow of electrolyhtes
Large intestine (5 ft) • Mechanical digestion— haustral churning, peristalsis, mass peristalsis • Chemical digestion • Absorption • Feces formation • Reflexes in the Colon
Ulcerative Colitis
Defecation reflex • Mass peristaltic movements • Voluntary contractions of diaphragm and abdominals • Parasympathetic input • Voluntary input
Resources • • Human Digestion Heart Burn Video Peristalsis Animation Digestive System
- Cell tissue organ organ system organism
- Cell tissue organ organ system organism
- Organ and organ system
- Mouth function in digestive system
- Major and accessory organs of the digestive system
- Which is an accessory organ of the digestive system
- Which is an accessory organ of the digestive system
- Venn diagram of chemical and mechanical digestion
- Circularory system
- Organ penyusun sistem gerak pada hewan
- Tractus respiratorius
- Organ penyusun sistem indra
- Digestive system digram
- How are ethnic groups and religious groups related
- Nervous system and digestive system
- Tunics of digestive tract
- Common bile duct empties into
- Alimentary canak
- Alimentary canal of earthworm
- Introduction about digestive system
- Histology of digestive tract
- Alimentary tract and metabolism
- Alimentary canal
- Alimentary canal of mammals
- Which is not part of the alimentary canal
- Figure 14-1 digestive system
- Phylum
- Nematodes acoelomate
- The first phylum to have a complete alimentary canal is
- Alimentary cannel
- Alimentary canal
- Alimentary canal pathway
- Optic lobes
- Small intestine
- Organ system definition
- Alimentary menu
- Mucosa submucosa muscularis externa serosa
- What is function of goblet cells
- Gastrovascular cavity vs alimentary canal
- Questron technologies corp
- The human bodywhat is an organ system?
- ______ means "little organ."
- Primary sex organ of the male reproductive system? *
- Plant organ system
- Level of organization organ system
- Organ system examples
- Organ system
- Is a heart an organ system
- Pulmon enfermo