ANAT 200 Final Review

Ingestion

Food and liquid intake (oral cavity)

Mechanical processing

Swirling, mixing, churning, propulsive motions in GI tract (entire tube)

Compaction

Dehydration of undigested material and waste into feces (colon to anus)

Digestion

Chemical and enzymatic breakdown of sugars, lipids, and proteins into small molecules (mostly in stomach, small intestine)

Secretion

Acids, enzymes, and buffers by accessory organs

Absorption

Movement of molecules, electrolytes, vitamins, and water into interstitial fluid

- blood vessels -> liver -> heart -> rest of body

Excretion

Elimination of undigested residue and waste products

Main components of GI system

- Oral cavity

- Pharynx

- Esophagus

- Small intestine

- Large intestine

- Anus

Accessory organs of GI system

- Salivary glands

- Liver

- Gallbladder

- Pancreas

Components of small intestine

- Duodenum

- Jejunum

- Ileum

Components of large intestine

- Cecum

- Ascending colon

- Transverse colon

- Descending colon

- Sigmoid colon

- Rectum

Layers of GI tube

- Mucosa

- Submucosa

- Muscularis externa

- Serosa

Components of mucosa

- Epithelium (stratified or squamous depending on location)

- Lamina propria (connective tissue containing glands and immune cells)

- Muscularis mucosa (propels contents of glands in lumen)

Components of submucosa

Conduit for vasculature, nerves, and lymphatics; connective tissue

- Immune cells

- Some exocrine glands

- Submucosal nerve plexus

Components of muscularis externa

- Inner circular smooth muscle

- Outer longitudinal smooth muscle

- Myenteric plexus (controls GI motility)

- Skeletal muscle and beginning and end of tube

- Oblique smooth muscle in stomach

Components of serosa

Wrapping of the tube layer(s)

- Serous membrane (simple squamous epithelium + areolar CT)

- Continually produces watery fluid for lubrication

Location of pharynx

Behind nose, mouth, throat

Location of esophagus

Sits behind respiratory system and disphragm

Location of liver and gallbladder

Location of stomach

Location of spleen

Behind the stomach and left side of heart

Location of pancreas

Behind stomach

Organs in left upper quadrant

- Stomach

- Spleen

- Body and tail of pancreas

- Jejunum

- Transverse colon

- Left kidney

Organs in right upper quadrant

- Liver

- Gallbladder

- Duodenum

- Head of pancreas

- Transverse colon

- Right kidney

Organs in left lower quadrant

- Ileum

- Descending and sigmoid colon

Organs in right lower quadrant

- Ileum

- Cecum

- Appendix

- Ascending colon

Location of rectum and anus

In pelvis; inferior to abdominal quadrants

Abdominal quadrants

Vertical and horizontal planes intersecting at the unbilicus

Midclavicular plane

Sagittal plane through the middle of clavicles

Subcostal plane

Transverse plane below the ribs (L1)

Intertubercular plane

Transverse plane through the tubercles of iliac crests (L5)

Epigastric region

Region of the abdomen between the midclavicular planes and superior to the subcostal plane

Umbilical region

Region of the abdomen between the midclavicular planes and the subcostal and intertubercular planes

Hypogastric region

Region of the abdomen between the midclavicular planes and inferior to the intertubercular plane

Foregut

From abdominal esophagus to descending part of duodenum

- Vasculature: celiac trunk

- Innervation: celiac ganglia T7-T9

Midgut

From descending part of duodenum to left colic flexure of transverse colon

- Vasculature: superior mesenteric artery

- Innervation: SMA ganglia T9-T11

Hindgut

From left colic flexure of transverse colon to rectum

- Vasculature: inferior mesenteric artery

- Innervation: IMA ganglia T11-L1

Parasympathetic innervation of abdominal organs

Vagus nerve (CN X)

Superior mesenteric artery location

Organs supplied by superior mesenteric artery

- Pancreas (1/2)

- Duodenum (1/2)

- Jejunum

- Ileum

- Cecum and appendix

- Ascending colon

- Transverse colon

Descending aorta location and function

Supplies thoracic esophagus

Celiac trunk location

Organs supplied by celiac trunk

- Abdominal esophagus

- Stomach

- Spleen

- Liver

- Gallbladder

- Pancreas (1/2)

- Duodenum (1/2)

Inferior mesenteric artery location

Organs supplied by inferior mesenteric artery

- Descending colon

- Sigmoid colon

- Rectum

Gonadal artery location and function

Supplies ovaries/testes

Renal artery location and function

Supplies kidneys and adrenal glands

Splenic vein

Veinous equivalent of celiac trunk

Veins from body wall

Drain directly into inferior vena cava

Veins from GI tube

Go to liver for filtration via hepatic portal vein

Peritoneum

Serous membrane lining the peritoneal body wall and organs

Parietal peritoneum

Lines the peritoneal cavity; body wall - somatic innervation

Visceral peritoneum

Lines the peritoneal organs; viscera - autonomic innervation

Mesentary

Sandwich of peritoneum; 2 layers of peritoneum serves as a conduit for vessels, nerves, and lymphatics

Greater omentum

Large pouch of mesentery from greater curvature of stomach to transverse colon that forms an apron; contains blood, nerves, lymphoid tissue; lipid deposition for temperature control; immune function

Intraperitoneal

Within the peritoneal cavity

Retroperitoneal

Posterior to the peritoneum; anchored in place

Retroperitoneal organs

- Adrenal glands

- Kidneys and ureters

- Abdominal aorta

- Inferior vena cava

- Abdominal esophagus

- Most of duodenum

- Pancreas

- Ascending/descending colon

- Rectum

- Bladder

- Prostate

- Uterus

Oral mucosa

Stratified squamous epithelium that protects from abrasion and stress

Functions of oral cavity

- Sensory analysis of ingested material

- Mechanical digestion

- Lubrication by mixing ingested material with saliva (bolus)

- Start of enzymatic digestion (amylase)

Oral vestibule

Space between lips, cheeks, and teeth

Tonsils in the oral cavity

- Pharyngeal

- Palatine

- Lingual

Components of the pharynx

- Nasopharynx

- Oropharynx

- Laryngopharynx

Cheeks

Buccal fat pads + oral mucosa

Hard palate

Maxillae and palatine bones

Enamel

Hard, outermost layer of a tooth

Dentin

Alive component of a tooth covered by enamel and supplied by pulp

Pulp cavity

Cavity within a tooth that contains blood vessels and nerves

Gingiva

Gums (mucosa)

Bone surrounding teeth

Maxilla or mandible

Cement

Connective tissue that anchors tooth to periodontal ligament

Periodontal ligament

Forms gomphosis joint

Root canals

Neurovascular bundles that enter tooth from bone

Crown of tooth

Portion of tooth above mucosa

Neck of tooth

Portion of tooth in the gingiva

Root of tooth

Portion of tooth in bone

Incisors

Blade-like teeth that clip/cut food

Canines

Pointed teeth that tear/slash food

Premolars

Bicuspid teeth that crush/mash/grind food

Molars

Multi-cuspid teeth that crush/grind food

Upper dentition innervation

CN V2; superior alveolar nerve

Lower dentition innervation

CN V3; inferior alveolar nerve

Maxillary dental arcade

Mandibular dental arcade

Permanent teeth

32 teeth in adults; eruption from 6-18 years

- 2 (central and lateral) incisors

- 1 canine

- 2 premolars

- 3 molars

Deciduous teeth

20 teeth in children; eruption from 6-24 months and shed 6-12 years

- 2 incisors

- 1 canine

- 2 molars

- no premolars

Tongue muscle innervation

CN XII

Intrinsic muscles of tongue

Control shape of tongue

- superior longitudinal

- vertical

- transverse

- inferior longitudinal

Extrinsic muscles of the tongue

Function in swallowing

- palatoglossus

- styloglossus

- hyoglossus

- genioglossus

Anterior 2/3 of tongue

Anterior to terminal sulcus; innervated by CN V3 and CN IX

Posterior 1/3 of tongue

Posterior to terminal sulcus; innervated by CN VII via chorda tympani and CN IX

Taste receptors

Sweet, sour, salty, bitter, and umami; throughout all papillae of tongue

Salivary glands

Exocrine glands with ducts into the oral cavity; serous moistens food and mucus lubricates passage of food

Functions of saliva

- Amylase initiates carbohydrate digestion

- Buffers regulate oral pH

- Antibodies provide immune surveillance

- Dissolves chemicals that stimulate taste buds

Autonomic innervation of salivary glands

- Sympathetic: inhibits secretion

- Parasympathetic: stimulates secretion

Pharynx

- Common passageway for food, liquid, and air

- Ends at the proximal esophagus and trachea

- Innervated by CN X

- Glands secrete serous and mucus substances

- Stratified squamous epithelium

Muscles involved in swallowing

- Tensor and levator palatini elevate soft palate

- Pharyngeal constrictors and suprahyoid muscles help elevate the larynx and push the bolus towards esophagus

Movement of bolus

1. Contraction of circular muscles behind bolus

2. Contraction of longitudinal muscles in front of bolus

3. Contraction in circular muscle layer forces bolus forward

Segmentation

- Mainly circular muscle contraction

- Churns and mixes contents

- No movement in any direction

- Mechanical digestion

Peristalsis

Propels bolus along the length of the tube via coordination of circular and longitudinal muscles