GI System 1 Flashcards
What are the first four functions of the digestive system?
Ingestion: food and liquid intake (oral cavity)
Mechanical processing: swirling, mixing, churning, propulsive motions in tract (entire tube) (physical)
Compaction: dehydration of undigested material and waste into feces (colon to anus)
Digestion: chemical and enzymatic breakdown of sugar, lipids, and proteins into small molecules (chemical)
What are the last 3 functions of digestive system?
Secretion: acids, enzymes, buffers by accessory organs (salivary glands, liver, pancreas)
Absorption: movement of molecules, electrolytes, vitamins, and water into interstitial fluid (intestines, blood vessels, liver, rest of body)
Excretion: elimination of undigested residue and waste products (anus)
What are the accessory (exocrine) glands that are along the GI tract? (4) Which one is not a gland?
Salivary glands
Liver
Gallbladder (not a gland)
Pancreas
What are the elements of the digestive system and their subsections?
Oral cavity, pharynx, esophagus
Stomach
Small intestine: duodenum, jejunum, ileum
Colon: cecum, ascending, transverse, descending, sigmoid colon, rectum
Anus
What is the histology (layers) of the GI tract? (4)
Mucosa, submucosa, muscular externis layer, serosa
What is the histology of the glandular tissue? (3)
Epithelium
Exocrine (secretion into GI tube)
Endocrine (secretion into surrounding connective tissue- circulation)
What is the innermost layer of the GI tube and its 3 parts and their characteristics (1 each)?
Mucosa layer
1. Epithelium: simple or stratified (beginning has stratified and end has simple due to more stress/ absorption)
2. Lamina propria: connective tissue, glands/immune cells
3. Muscularis mucosa: propels content of glands in lumen
What is the second innermost layer of the GI tube? (3)
Submucosa: connective tissue layer
Conduit for vasculature, nerves and lymphatics
Immune cells, some endocrine glands (before and after stomach), submucosal nerve plexus
What is the third innermost layer of the GI tube? (5)
Muscularis externis: external muscle layer
Inner circular smooth muscle, outer longitudinal smooth muscle
Stomach: oblique smooth muscle
At the beginning and end of the tube this layer is skeletal (somatic)
Myenteric plexus (control GI motility)
What is the outermost layer of the GI tube? (4)
Serosa (wrapping of the tube) layer
Simple squamous epithelium and connective tissue (serous membrane)
Continually produces watery fluid that lubricates the peritoneal surfaces
Two layers: mesentery (see later)
What are the upper GI organs? (3)
Oral cavity, pharynx (behind nose, mouth, throat), esophagus
What are the abdominal GI organs? (9)
Liver/ gall bladder
Stomach, spleen, pancreas
Small intestines, kidneys, large intestines
Anal canal
What are the two upper quadrants and what is contained within them? (6 each)
Right upper quadrant: liver, gallbladder, duodenum, head of pancreas, transverse colon, right kidney
Left upper quadrant: stomach, spleen, body and tail of pancreas, jejunum, transverse colon, left kidney
What are the two lower quadrants and what is contained within them? (4 and 3)
Right lower quadrant: ileum, cecum, appendix, ascending colon
Left lower quadrant: ileum, descending and sigmoid colon
What are the three abdominal planes and where do they extend from?
- Midclavicular plane: middle of clavicle
- Subcostal plane: below the ribs (L1)
- Intertubercular plane: tubercles of iliac crest (L5)
What are the three abdominal regions? (3)
Epigastric region
Umbilical region
Hypogastric region
What are the three divisions of the gut, their characteristics and innervation?
Foregut: from abdominal esophagus to descending part of the duodenum (celiac trunk, same for innervation, celiac ganglia T7-T9)
Midgut: from descending part of duodenum to left colic flexure of the transverse colon (superior mesenteric artery, same for innervation from SMA ganglia T9-T11)
Hindgut: from left colic flexure of the transverse colon to rectum (inferior mesenteric artery, same for innervation IMA ganglia T11-L1)
What is the arterial vasculature for the upper 3 parts of the GI tract?
Descending aorta: thoracic esophagus
Celiac trunk: abdominal esophagus, stomach, spleen, liver, gallbladder, pancreas (1/2), duodenum (1/2)
Superior mesenteric artery: pancreas (1/2), duodenum (1/2), jejunum, ileum, cecum, appendix, ascending and transverse colon
What is the arterial vasculature for the lower three parts of the GI tube?
Renal artery: kidneys, adrenal glands
Gonadal artery: ovaries and testes
Inferior mesenteric artery: descending colon, sigmoid colon, rectum
What is the venous vasculature for the GI tube?
Generally similar to the arterial vasculature except for NO CELIAC VEIN (splenic vein instead)
ALL vasculature from the GI tube will end up in the liver to be filtered by the hepatic portal vein
Veins from the body wall (renal, common iliac, gonadal) will drain directly into the inferior vena cava
What is the peritoneum? What are two types of it?
Peritoneum: serous membrane lining the peritoneal (abdominal) body wall and organs
Parietal peritoneum: lining the peritoneal cavity (body wall- somatic innervation)
Visceral peritoneum: lining the peritoneal organs (viscera- autonomic innervation)
What is the mesentery (proper)?
Sandwich of peritoneum (2 layers of peritoneum serves as conduit for vessels, nerves and lymphatics)
Many have specific ex. mesocolon (around different parts of the colon) or omentum
What are the two different parts of the omentum?
Greater omentum: mesentery from greater curvature of stomach to transverse colon
Lesser omentum: mesentery from lesser curvature of stomach to liver (important structures found here)
What are some characteristics of the greater omentum? (4)
Large pouch of mesentery that forms an apron
Blood, nerves, and lymphoid tissues are found
Lipid deposition for temperature control
Has immunological function
What is the difference between intraperitoneal and retroperitoneal?
Intraperitoneal: inside the peritoneal cavity
Retroperitoneal: outside the peritoneum not within the membrane
What structures are retroperitoneal and intraperitoneal?
RP( 4 big categories), IP (3)
Intraperitoneal: small intestine, most of gut tube and liver
Retroperitoneal: everything not associated with GI in the abdomen (adrenal glands, kidneys, ureters), big vessels (abdominal aorta and IVC), some anchoring organs (most of duodenum, abdominal esophagus, pancreas, ascending and descending colon), all pelvic organs below peritoneum (rectum, urinary bladder, prostate, uterus)
What are some characteristics of the oral cavity?
Stratified squamous epithelium (oral mucosa) protects from abrasion/ stress, in oral beginning and end of tube
Sensory analysis of ingested material
Mechanical digestion (tongue, teeth, cheeks, palatal surface)
Lubrication by mixing ingested material with saliva (bolus)
Start of enzymatic digestion: mainly amylase (to start the digestion of large carbs)
What are the boundaries of the oral cavity? (7, include the types of tonsils, etc)
Lips/skin, hard palate (maxilla and palatine bones), soft palate to uvula (midline)
Pharynx: nasopharynx, oropharynx, laryngopharynx
Cheeks: buccal fat pads and oral mucosa
Oral vestibule: space between lips, cheeks and teeth
Tonsils: pharyngeal tonsils, palatine tonsils, lingual tonsils
What is the anatomy of the tooth from surface to jaw? (3 major categories, 2 in first, 1 in second, 4 in third)
Crown: enamel, dentin, pulp cavity
Neck: gingiva (gum, mucosa)
Root: bone (maxilla, mandible), cement (sticky connective tissue), periodontal ligament (gomphosis joint), root canals (neurovascular bundle)
What are the different types of teeth and the type of mechanical processing they do? (4)
Incisors: blade like, clip/cut food, 2 central/lateral
Canines: pointed, tears/slashes food, 1
Premolars: bicuspid, crush/mash/grind food (2)
Molars: multicuspid, crush/grind food (3)
What is the sensory innervation of the teeth for upper and lower dentition?
CN V: Trigeminal nerve
Upper dentition in maxillae: CN V2, maxillary branch of trigeminal nerve, superior alveolar nerve
Lower dentition in mandible: CN V3, mandibular branch of the trigeminal nerve, inferior alveolar nerve
What are the two types of teeth?
Permanent teeth: 32 teeth, eruption between 6-18
Deciduous teeth: 20 teeth, no premolars, eruption from 6-24 months, shed 6-12 years
What are the skeletal muscles of the tongue and their innervation? (1 nerve, 2 types of muscle groups each with a function and 4 muscles)
Most tongue muscles innervated by CN XII (hypoglossal nerve)
Intrinsic (3 orientations): shape of tongue for speech, superior/inferior longitudinal, vertical, transverse, septum
Extrinsic (4 muscles): swallowing, push the tongue superior and posterior, all the ones ending in glossus (palato, stylo, hyo, genio)
What nerves supply general sensation to the tongue? (2)
Mandibular branch of CN V (CN V3)
Glossopharyngeal nerve (CNIX)
What are the taste receptors innervated by? (2)
Sweet, sour, bitter, umami, salty found throughout all papillae
Facial nerve via chorda tympani (CN VII)
Glossopharyngeal nerve (CN IX)
What are the three parts of the tongue?
Apex
Body (anterior 2/3)
Root (posterior 1/3)
What are 4 characteristics of salivary glands, and their overarching purpose?
Purpose: enzymatic breakdown
Exocrine glands with ducts into oral cavity (serous moistens food via enzymes and mucus lubricates passage of food)
Saliva (even w/o good to control population of bacteria in oral cavity: amylase initiates digestion of carbs, buffers regulate oral pH, antibody production, dissolves chemicals that stimulate taste buds
Autonomic nervous system: parasympathetic stimulates secretion, sympathetic inhibits
Extra secretion stimulated by: presence of food in the mouth, taste, sight, smell, or thought of food
What are some characteristics of the pharynx? (4)
Common passageway for food, air, and liquid (stratified squamous epithelium)
Ends at location of the proximal esophagus and trachea
Glands throughout secrete serous and mucus substances
Innervation: CN X (vagus nerve)
What are the muscles that control the pharynx? (6)
Palatal muscles (tensor and levator palatini) elevate soft palate during swallowing
Pharyngeal constrictor (superior, middle, inferior) and suprahyoid muscles help elevate larynx and push bolus (chewed food mixed with saliva) towards esophagus
What is peristalsis? (4)
Peristalsis is constriction of the esophagus
Propels bolus along the length of the tube
Coordination of circular and longitudinal muscles, contract one after the other
Propulsion
What is segmentation?
Mainly circular muscle layer
Churn and mix contents
NO movement in any particular direction
Mechanical digestion
