The Digestive System And Metabolism 14 Flashcards
Ingestion
Taking in food
Digestion
Breaking food into nutrient molecules
Absorption
Movement of nutrients into bloodstream
Defecation
Getting rid of indigestible waste
Groups of digestive organs
1.Alimentary canal
2. Accessory digestive organs
Alimentary canal GI tract
Continuous hollow tube that helps ingest, digest, absorb, defecate (mouth to anus )
Accessory digestive organs
Assist in digestion in various ways
Teeth, tongue and other big digestive organs (liver pancreas, gallbladder)
Organs of alimentary canal
Mouth
Pharynx
Esophagus
Stomach
Small intestine
Large intestine
Anus
Mouth (oral cavity) lined with
Mucous membrane lined cavity
Lips (labia)
Protect anterior opening
Cheeks
Form the lateral walls
Hard palate
Forms anterior roof
Soft palate
Forms posterior roof
Uvula
Fleshy projection of soft palate
Vestibule
Space between lips externally and teeth and gums internally
Oral cavity proper
Area contained by teeth
Tongue attached by
Attached at hyoid bone and styloid processes of skull
Attached by lingual frenulum to floor of mouth
Palatine tonsils
@ posterior end of oral cavity
Lingual tonsil
At base of tongue
Gingivae
Gums
Functions of mouth
1.Mastication
2. Mixes chewed food with saliva
3.tongue initiates swallowing
4. Tastebuds on tongue allow for taste
Pharynx function in eating
Passage for food, fluid, air
Food passes to from the mouth posteriorly to the
Oropharynx
Laryngopharynx
Location of Laryngopharynx
Under oropharynx
Continuous with esophagus
Food is propelled to esophagus by two layers of skeletal muscle in pharynx
Longitudinal outer layer
Circular inner layer
What propels food?
Peristalsis
Alternating contractions of muscle layers
Anatomy of esophagus
10 inches long
Runs from pharynx to stomach through diaphragm
Physiology of esophagus
- Uses peristalsis to take food to stomach
2.passageway for food only. (Resp system branches off after pharynx(
Layers of tissue that make alimentary canal organs (innermost to outermost)
- Mucosa
- Submucousa
- Muscularis externa
4.serosa
Lines cavity aka lumen
Innermost, moist membrane
Mucosa
Mucosa made of
1.Surface epithelium that’s mostly simple columnar
Esophagus made of stratified squamous
- Small amount of connective tissue (lamina propria)
- Scanty smooth muscle layer
Submucousa
- Under mucosa
- Soft, connective tissue w/ blood vessels, nerve endings, mucosa Associated Lymphoid tissues, lymphatic vessels
Muscularis externa
Smooth muscle
Inner circular layer, outer longitudinal layer
Serosa
Outermost layer of wall; contains fluid producing cells
Visceral peritoneum of serosa
Innermost layer continuous with outermost layer
Parietal peritoneum of serosa
Outermost layer that lines the abdominopelvic cavity by way of the mesentery
Alimentary Wall canals have 2 intrinsic nerve plexuses
Submucosal nerve plexus
My enteric nerve plexus
Function of alimentary canal nerve plexuses
Regulate mobility and secretory activity of GI tract organs
Submucosal nerve plexus
Controls glandular secretions
Electrolyte and water transport
Blood flow
Myenteric nerve plexus
Peristaltic movement of bowels
C-shaped organ on left side of abdominal cavity
Stomach
Food enters the stomach from
Cardioesophageal sphincter from the esophagus
Food from stomach empties into the small intestine from
Pyloric sphincter (valve)
Regions of the stomach
- Cardial
2.Fundus
3.Body
4.Pylorus
Cardia (cardial)
Near heart
Surrounds the cardioesophageal sphincter
Fundus
Expanded portion lateral to cardiac region
Body
Mid portion
Greater curvature of stomach Body
Convex lateral surface
Lesser curvature of stomach Body
Concave medial surface
Pylorus
Funnel shaped terminal end of stomach
Empties into duodenum
Stomach can stretch and hold what capacity of food when full?
4L (1 gal)
Rugae
Internal folds of mucosa present when stomach is empty
Lesser omentum
Double layer of peritoneum
Extends from liver to lesser curvature of stomach
Greater omentum
1.Another extension of peritoneum
2.Covers abdominal organs
3.Fat insulates, cushions and protects abdominal organs
What kind of cells make stomach mucosa
Simple columnar epithelium made of mucous cells
Describe mucus produced by mucous cells?
Bicarbonate-rich alkaline mucous
The stomach mucosa is dotted by
Gastric pits leading to gastric glands that secrete gastric juices
Intrinsic factor
Needed for vitamin B-12 absorbtion for small intestine
What secretes intrinsic factor?
Gastric pits
Chief cells
Make protein digesting enzymes
Secrete pepsinogen
Pepsinogens
Protein digesting enzymes
Parietal cells
Make HCL acid that activates enzymes
Mucous neck cells
Make thin acidic mucus (different from mucus made by mucous cells of the mucosa)
Enteroendocrine cells
Produce local hormones such as gastrin
Pepsinogen is known as inactive form, becomes active when
Comes in contact with HCL made by parietal cells
Pepsin is active form of
Pepsinogen
Functions of stomach
1.Temporary storage tank for food
2. Site of food breakdown
3. Chemical breakdown of protein begins
4. Delivers chyme to small intestine
Chyme
Processed food
Body’s major digestive organ
Small instestine
Longest portion of alimentary tube + length
Small instestine
2-4m, or 7-13 ft in living person
Small intestine function
Site of nutrient absorption in the blood
Small intestine extends from
Pyloric sphincter to ileocecal valve
Small instestine is suspended from
Posterior abdominal wall by the mesentery
Subdivisions of small intestine
Duodenum
Jejunum
Ileum
Chemical digestion begins in the
Small intestine
Steps of chemical digestion
- Enzymes from intestinal cells and pancreas carried to duodenum by pancreatic ducts
Bile, formed by liver enters the ______ via the ____ _______
Duodenum
Bile duct
Location where main pancreatic duct and bile ducts join
Hepatopancreatic ampulla
Purpose of structural modifications in small intestine
Increase surface area for food absorption
Decrease in number towards end of small intestine
Vili
Fingerlike projections formed by the mucosa
House a capillary bed and lacteal
Villi
Microvilli
Tiny projections of the plasma membrane
(Brush border enzymes)
Circular folds
Plicae circulares
Deep folds of mucosa and submucosa
Peyer’s patches
Collections of lymphatic tissues in small intestine
In which layer are peyer’s patches located?
Submucousa
Increase in number towards end of the small intestine (more in ileum)
Peyer’s patches
Why do we need more peyer’s patches towards the end of the small intestine?
Remaining food residue contains much bacteria
Lacteal
Lymphatic vessel that carries fat from intestines
Why is the large intestine called the large intestine?
Larger in diameter, but it’s shorter in length at 1.5 m
Large intestine extends from
Ileocecal valve to the anus
Subdivisions of large intestine
Cecum
Appendix
Colon
Rectum
Anal canal
Saclike first part of large intestine?
Cecum
Hangs from cecum
Appendix
Appendix
Accumulation of lymphoid tissue that sometimes becomes inflamed