1
Q
Organs of the Digestive System
A
- Two main groups
- Alimentary canal (gastrointestinal or GI tract [gastrointestinal tract)– continuous coiled hollow tube
- Accessory (things that help digestion) digestive organs
2
Q
Organs of the Alimentary Canal (GI Tract)
A
- Pathway from mouth to anus (food passes through)
- Mouth
- Pharynx
- Esophagus
- Stomach
- Small intestine (97% of chemical digestion)
- Large intestine
- Anus
3
Q
Mouth (Oral Cavity) Anatomy
A
- Lips (Labia)– Protect the anterior opening
- Cheeks– Form the lateral walls– Buccal cavity
- Hard palate- forms the anterior roof
- Soft palate- forms the posterior roof
- Uvula- Fleshy projection of the soft palate (Lymph tissue)
4
Q
Mouth Physiology
A
- Mastication: Chewing of food
- Mixing masticated food with saliva (Bolus)
- Initiation of swallowing by the tongue
- Tonge rolls back
- Larynx rises
- Constriction
- Deglutition (swallowing)
- Allows for the sense of taste
5
Q
Pharnyx Anatomy
A
- Nasopharynx: Not part of the digestive system
- Oropharynx: Posterior to oral cavity
- Laryngopharynx: Below the oropharynx and connected to the esophagus
6
Q
Teeth (Function)
A
- Function is the masticate (chew) food
- Humans have two sets of teeth
- Deciduous (baby or “milk” teeth)
- 20 teeth are fully formed by age two
7
Q
Permanent Teeth
A
- Replace deciduous teeth between the ages of 6 & 12
- A full set of 32 teeth, but some people do not have wisdom teeth (third molars)
- If they do emerge, the wisdom teeth appear between ages 17- 25
8
Q
Classifications of Teeth
A
- Incisors: cutting
- Canines- tearing or piercing
- Premolars- grinding
- Molars – grinding
9
Q
Regions of the Tooth
A
- Crown: Exposed part
- Neck: region in contact with gum
- Root: attaches tooth to periodontal membrane
10
Q
Crown
A
- Enamel- hardest substance in the body
- Dentin- found deep to the enamel and forms the bulk of the tooth
- Pulp cavity: contains connective tissue, blood vessels, and nerve fibers
- Root canal: where the pulp cavity extends into the root
11
Q
Neck
A
- Region in contact with the gum
- Connects crown to root
12
Q
Root
A
- Cementum- Covers outer surface
- attaches the tooth to the periodontal membrane
13
Q
Salivary Glands
A
- Three pairs of salivary glands empty secretions into the mouth
- Parotid glands: In front of the ear
- Submandibular Below the mandible (anterior)
- Sublingual glands: below the tongue (Posterior)
- Sublingual is in back of the submandibular
14
Q
Saliva
A
- Mixture of mucus and serous fluids
- Helps to form a food bolus
- Contains salivary amylase to begin starch digestion
- Dissolves chemicals so they can be tasted
15
Q
Pharynx Physiology
A
- Serves as a passageway for air and food
- Food is propelled to the esophagus by two muscle layers
- Longitudinal inner layer
- Circular outer layer
- Food movement is by alternating contractions of the muscle layers (peristalsis: wave like contractions)
16
Q
Esophagus Anatomy and Physiology
A
- Anatomy
- About 10 inches long
- Runs from pharynx to stomach through the diaphragm
- Physiology
- Conducts food by peristalsis (slow rhythmic squeezing)
- Passageway for food only (respiratory system branches off after the pharynx)
17
Q
Layers of the Alimentary Canal Organs
A
- Mucosa
- Submucosa
- Muscularis Externa
- Serosa
18
Q
Mucosa
A
- Innermost, moist membrane consisting of -Surface epithelium
- Small amount of connective tissue (lamina propria)
- Small smooth muscle layer
19
Q
Submucosa
A
- Just beneath the mucosa
- Soft connective tissue with blood vessels, nerve endings. and lymphatics
20
Q
Muscularis Externa
A
- Smooth muscle
- Inner circular layer
- Outer longitudinal layer
21
Q
Serosa
A
- Outermost layer of the wall that contains fluid-producing cells
- Visceral peritoneum- outermost layer that is continuous with the innermost layer
- Parietal peritoneum- innermost layer that lines the abdominopelvic cavity
22
Q
Alimentary Canal Nerve Plexus
A
- Bundle of nerves
- Two important nerve plexuses serve the alimentary canal
- Both are part of the autonomic nervous system
- Submucosal nerve plexus
- Myenteric nerve plexus
- Function is to regulate mobility and secretory activity of the GI tract organs
23
Q
Small Intestine
A
- The body’s major digestive organ (19-21 feet)
- Site of nutrient absorption into the body
- Function: Chemical digestion
- Muscular tube extending from the pyloric sphincter to ileocecal valve
- Suspended from the posterior abdominal wall by the mesentery(tissue)
24
Q
Chemical Digestion of the Small Intestine
A
- Chemical digestion begins in the small intestine
- Enzymes are produced by
- Intestinal glands
- Pancreas
- Pancreatic ducts carry enzymes to the small intestine
- Bile, formed by the liver, enters via the common bile duct (emulsification)
25
What do certain nutrients break down to?
Protein--> Amino acids
Carbohydrates--> Monosaccharides
Lipids--> Fatty acids and glycerol
Nucleic acids--> nucleotides
26
Small Intestine Anatomy
- Three structural modifications that increase surface area
- Microvilli- Tiny projections of the plasma membrane (create a brush border appearance)
- Villi- fingerlike structures formed by the mucosa
- Circular folds (plicae circulares)-- deep folds of mucosa and submucosa
27
Lacteal
- absorbs fatty acids and glycerol
- which makes lymph (tissue fluid)
- Lymph makes antibodies
28
Intestinal Juices
- sucrase (works on sucrose to give u glucose)
- lactase (works on lactose--> glucose)
- maltase (works on maltose to glucose)
29
Subdivisions of the Small Intestine
- Duodenum 1 ft
- Attached to the Stomach
- Curves around the head of the pancreas
- Jejunum (8-10 feet)
- Attaches anteriorly to the duodenum
- Ileum (longest part)
- Extends from jejunum to large intestine
30
Stomach Anatomy
- Located on the left side of the abdominal cavity
- Food enters at the cardioesophageal sphincter
- Food (chyme) empties into the small intestine at the pyloric sphincter (valve)
31
Regions of the Stomach
- Cardiac region: near the heart
- Fundus: expanded portion lateral to the cardiac regions
- Body: midportion
- Pylorus- funnel-shaped terminal end
32
Rugae
-Internal folds of mucosa
33
External Regions of the Stomach
- Lesser curvature: concave (curving in) medial surface
| - Greater curvature: convex (curving out) lateral surface
34
Layers of the Peritoneum Attached to the Stomach
- Lesser omentum: attaches the liver to the lesser curvature
- Greater omentum: attaches the greater curvature to the posterior body wall
- Contains fat to insulate, cushion, and protect abdominal organs
- Has lymph nodules containing macrophages
35
Stomach Physiology
- Temporary storage tank for food
- Site of food breakdown
- Chemical breakdown of protein begins
- Delivers chyme (processed food) to the small intestine (to turn into chyle)
36
The Stomach can absorb...?
- Alcohol
| - Asprin
37
Structure of the Stomach Mucosa
- Mucosa is simple columnar epithelium
- Mucous neck cells- produce a sticky alkaline mucus
- Gastric glands- situated in gastric pits and secrete gastric juice (2.0 pH)
- Chief cells- produce protein-digesting enzymes (pepsinogens)
- Parietal cells- produce hydrochloric acid
- Enteroendocrine cells- produce gastrin (hormone)
38
Large Intestine
- Large in diameter, but shorter in length, than the small intestine
- Frames the internal abdomen
39
Amylase
- Enzyme
| - Turns a starch into maltose
40
Peristalysis
-Wave like movement of food (bolus) through the pharynx
41
Digestive System Functions
- Ingestion- Taking in food
- Digestion- breaking food down both physically and chemically
- Absorption-- movement of nutrients into the bloodstream
- Defection- rids the body of indigestible waste
42
What is Neutralized Chyme called?
-Chyle
43
Cecum and Appendix (Large Intestine Anatomy)
- Cecum: Saclike first part of the large intestine
- Appendix:
- Accumulation of lymphatic tissue that sometimes becomes inflamed (appendicitis)
- Hangs from the cecum
44
Colon (Large Intestine Anatomy)
- Ascending: travels up right ride of abdomen
- Transverse: travels across the abdominal cavity
- Descending: travels down the left side
- Sigmoid: enters the pelvis
45
Rectum and Anus (Large Intestine Anatomy)
- Rectum and anal cavity: also in pelvis
- Anus: Opening of the large intestine
- External anal sphincter- formed by skeletal muscle and under voluntary control
- Internal involuntary sphincter- formed by smooth muscle
- These sphincters are normally closed except during defecation
46
Large Intestine Anatomy
- No villi present
- Goblet cells produce alkaline mucus which lubricates the passage of feces
- Muscalaris externa layer is reduced to three bands of muscle called teniae coli
- These bands cause the wall to pucker into haustra (pocket-like sacs)
47
Parts of the Large Intestine
- Cecum
- Appendix
- Colon
- Rectum
- Anus
48
Pancreas
- Found posterior to the parietal peritoneum
- Extends across the abdomen from spleen to duodenum
- Produces a wide spectrum of digestive enzymes that break down all categories of food
- Enzymes are secreted into the duodenum
- Alkaline fluid introduced with enzymes neutralizes acidic chyme coming from the stomach
- Hormones produced by the pancreas
- Insulin (controls sugar level of blood)
- Glucagon (helps stabilize low blood-sugar levels)
49
Liver
- Largest gland in the body
- Located on the right side of the body under the diaphragm
- Consists of four lobes suspended from the diaphragm and the abdominal wall by the falciform ligament-Connected to the gallbladder via the common hepatic duct
50
Muscles for Chewing
- Buccinator
- Temporalis
- Masseter
51
Peritoneum lines???
-The cavity
Anatomy/ Physiology
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