Anatomy Unit 5: Chps. 26-28 Flashcards
What are the digestive organs?
Makes up the…
- Digestive/alimentary canal: continuous tube of organs where food travels through and is eliminated as feces
- Accessory digestive organs: Assist digestion in the GI tract
What is/makes up the digestive tract/alimentary canal?
Oral cavity
Pharynx
Esophagus
Gastrointestinal (GI) tract:
- Stomach
- Small intestine (SI)
- Large intestine (LI)
What organs are part of the gastrointestinal (GI) tract?
Stomach
Small intestine (SI)
Large intestine (LI)
What are the accessory digestive organs and their function?
Teeth
Tongue
Salivary glands
Liver
Gallbladder
Pancreas
What is the general functions of the digestive system?
Ingestion
Digestion:
- Mechanical digestion
(Segmentation)
- Chemical digestion
Propulsion:
- Peristalsis
Secretion
Absorption
Elimination/Defecation
What is digestion and the different types of digestion?
Digestion: breakdown of food into smaller structures or molecules
1) Mechanical digestion: physical break down into smaller structures to increase surface area for enzymes to act on food
2) Chemical digestion: that breakdown macromolecules into monomers by digestive enzymes
Name examples of mechanical digestion
- Chewing/mastication of the teeth
- Churning of the stomach
- Segmentation: mechanical digestion by mixing of food and digestive secretion along the intestines
What are the different types of propulsion?
– Swallowing/deglutition: voluntary passing of food down the alimentary canal
– Peristalsis: muscular contraction that propels food down alimentary canal
What are the layers of the digestive tract?
1) Mucosa
- Epithelium
- Lamina propria
- Muscularis mucosae
2) Submucosa
3)Muscularis externa
- Inner circular layer
- Outer longitudinal layer
4) Serosa
- Areolar tissue
- Mesothelium
5) Adventitia
What is the mucosa?
inner layer of the digestive tract that faces the lumen (space where food/bolus/chyme/feces travels through)
What are the three parts of the mucosa and their definitions?
– Epithelium
* Simple columnar epithelium
* Stratified squamous epithelium
– Lamina propria: loose connective tissue
– Muscularis mucosae: contracts to create grooves/ridges to increase surface area to contact with food to increase absorption
What types of epithelium are in the mucosa of the digestive tract and where are they located in the alimentary canal and their function?
- Simple columnar epithelium: for most of the digestive tract
- Stratified squamous epithelium: from oral cavity to esophagus and at the end of the anal canal (protection from friction)
What is the mucosa-associated lymphatic tissue?
mucosa contains a lot of lymphocytes and lymphatic nodules to help fight off pathogens
What is the submucosa and what does it contain?
made of loose connective tissue with blood vessels, lymphatic vessels, nerve plexus, and possibly glands
- MALT is also found here
What is the muscularis externa?
typically two smooth muscles layers
What are the different layers of the muscularis externa?
- Inner circular layer: circular smooth muscles that prevents the backflow of food/etc
- Outer longitudinal layer: longitudinal smooth muscles that propels food/etc forwards
What other structures does the inner circular layer form?
Sphincters: thickened circular layers that regulate the flow of food/etc within the digestive tract
What is the serosa?
outermost layer of the digestive tract from the lower esophagus to the large intestine prior to the rectum and is the continuation of the visceral peritoneum.
What parts are contained within the serosa? Where do you find serosa?
– Areolar connective tissue
– Simple squamous mesothelium: simple squamous epithelium
What is adventitia and how is it different from serosa? Where do you find adventitia?
most outer layer of the pharynx, most of the esophagus, and rectum with their connective tissue blending into other connective tissues of other organs
What are dense bodies?
Found on the sarcolemma of smooth muscles and are similar to Z discs of skeletal muscles
– Anchor intermediate filaments so when the smooth muscles contract, the muscle cell shortens
What are the different types of smooth muscles? How are they different and where do you find them?
– Single unit/visceral: located in walls of hollow organs (ie: uterus, blood vessels, digestive viscera)
* Cells are connected by gap junctions so when it contracts, it contracts as a single unit
* Some are autorhythmic
– Multi-unit: located within the eye and arrector pili muscles
* Cells are in bundles or single smooth muscle cells without gap junctions with each cell with a neuron innervating it
What is the source of calcium for smooth muscles?
sarcoplasmic reticulum and extracellularly
What is the enteric nervous system?
regulates motility, secretion, and blood flow of the esophagus, stomach, and intestines; regulated by parasympathetic system
What structures are part of the enteric nervous system and where are they found?
– Submucosal/Meissner plexus: within the submucosa layer for the muscularis mucosae and glandular secretion
– Myenteric/Auerbach plexus: between the muscularis externa layers for peristalsis
What is the peritoneum?
serous membrane lining the viscera and abdominopelvic walls to reduce friction between viscera and walls
What are the different parts of the peritoneum?
– Parietal peritoneum: lines the abdominopelvic walls
➢ Peritoneal cavity: potential space between the parietal and visceral peritoneum where serous fluid prevents friction
– Visceral peritoneum: lines the viscera
What are retroperitoneal organs and name examples?
posterior organs behind the parietal peritoneum (ie: duodenum, pancreas, ascending/descending colon, rectum)
What is mesentery?
they are peritoneum that connect visceral peritoneum of organs and the parietal peritoneum
What are the different types of mesenteries and their location?
– Falciform ligament: connects liver to anterior abdominal wall and diaphragm
– Greater omentum: covers the abdominal organs from the greater curvature of the stomach
– Lesser omentum: connects the lesser curvature of stomach to the liver
– The mesentery/mesentery proper: suspends most of SI from the posterior abdominal wall
– Mesocolon: peritoneum that suspends parts of the large intestine to posterior abdominal wall
* Transverse mesocolon: suspends the transverse colon from the posterior wall
* Sigmoid mesocolon: suspends the sigmoid colon from the posterior wall
What is the oral cavity? What is the tissue surrounding the oral cavity?
“mouth” and entrance of GI tract lined with nonkeratinized stratified squamous epithelium and is surrounded by the labia (lips), buccae (cheeks), palate, and tongue
What are the functions of the oral cavity?
– Ingestion of food
– Taste and touch sensation
– Mastication (chewing): mechanical digestion
– Chemical digestion via salivary enzymes
– Deglutition (swallowing)
– Speech
– Respiration
Know the definition of ingestion, mastication, deglutition
- Ingestion: Putting solid/liquids into oral cavity
- Mastication: Chewing
- Deglutition: swallowing
What are the oral cavity organs and function
- Labia/Lips: thin keratinized stratified squamous epithelium
- Buccae/Cheeks: holds food within mouth when chewing
- Gingivae: “gums” covers the alveolar processes of mandible & maxillae and supports teeth
- Tongue: for gustation/taste, sound production, mastication, deglutition (swallowing), and defense (lingual tonsil)
- Palate: roof of the oral cavity and separates it with nasal cavity
– Hard palate: anterior part made of maxillary palatine processes and palatine bones
– Soft palate: skeletal muscle helps close off nasopharynx preventing it from entering nasal cavity - Uvula: posterior portion of soft palate that also closes off nasopharynx and for producing certain sounds
➢ Fauces: posterior opening to the oropharynx
What are salivary glands?
Produces saliva
What is in saliva?
mostly water + lots of stuff (digestive enzymes, mucin, electrolytes, defensive secretions)
What cells make saliva and what does each individually make?
– Serous acini (darker staining): produces water, enzymes, electrolytes, and defensive secretions to moisten food for taste, chemical digestion, and defense
» Salivary amylase: digest carbohydrates
»Lingual lipase: digest triglycerides but activated at low pH
– Mucous acini (lighter staining): produces thick mucus made of mucin and water to lubricate food
What are the different types of salivary glands and how they differ?
– Parotid salivary glands: largest salivary gland but produces 25-30% of saliva
* Serous acini only
– Submandibular salivary glands: produces the most saliva (60-70%)
* Serous and Mucous acini
– Sublingual salivary glands: produces the least saliva (3-5%)
* Serous and Mucous acini but mostly mucous acini
What are dentition and its general function?
Teeth/Dentition: for mastication
What are the regions of a tooth?
- Crown: exposed part of tooth
- Neck: part between the crown and root
- Root: anchors tooth in alveolus
What are the tooth structures and definition?
- Enamel: outer layer of the crown made of calcium phosphate crystals (hardest substance in body)
- Cementum/cement: outer layer of the root
- Dentin: hard substance making bulk of tooth
- Pulp cavity: center of tooth with pulp where blood vessels and nerves are located
- Root canal: space that leads from the root to the pulp cavity
- Pulp: loose connective tissue, blood and lymphatic vessels, and nerves that fill the root canal and pulp cavity
- Periodontal ligaments: gomphosis joint that binds root to alveolus
What is the different between deciduous vs permanent teeth?
- Primary/deciduous teeth: “baby/milk teeth” consist of 20 teeth
- Secondary/permanent teeth: “adult teeth” consist of 32 teeth
What are the different teeth and their definition?
– Incisors (8): anterior teeth
* Central (4)
* Lateral (4)
– Canines/cuspids (4): posterior and lateral to incisors for puncturing food
– Premolars/bicuspids (8): have cusps to crush and grind food
* 1st (4)
* 2nd (4)
– Molars (12): most posterior teeth with cusps and 3 or 4 roots for grinding
* 1st (4)
* 2nd (4)
* 3rd : “wisdom teeth” (4)
What are the different regions of the pharynx that food passes through and their epithelium?
made of nonkeratinized stratified squamous epithelium
- Oropharynx: posterior to the oral cavity where food will enter the…
- Laryngopharynx: posterior to the larynx where food will enter the esophagus
What does the esophagus do and what tissue does it contain?
Esophagus: peristalsis carries bolus from pharynx to stomach and is made of nonkeratinized stratified squamous epithelium to protect from abrasion and contains some skeletal muscle as well as smooth muscle
What is the smooth muscle at the end of the esophagus called and its function?
Lower/Inferior esophageal sphincter/esophagealgastric /cardiac sphincter: weak circular smooth muscle that preventing material from stomach from regurgitating
What are the layers of the esophagus?
– Mucosa: made of non-keratinized stratified squamous epithelium
– Submucosa: esophageal glands
– Muscularis externa
– Mostly adventitia within thoracic cavity; serosa in the abdominal cavity
What is different about esophagus’ muscularis externa?
– Muscularis externa:
* skeletal muscles (upper 1/3)
* Both skeletal and smooth muscles (middle 1/3)
* Smooth muscles (lower 1/3)
What is the general function of the stomach and examples of it?
- Function: location where bolus becomes chyme as it mixes with gastric secretion
– Mechanical digestion: churning and mixing by the stomach
– Chemical digestion: gastric enzymes and hydrochloric acid (HCl)
– Storage of food as it is digesting
– Limited absorption (aspirin, lipid soluble drugs)
What is chyme?
Gastric juices and food (bolus)
What are the structures/curvatures of the stomach?
– Greater curvature: inferior, convex portion of the stomach that the greater omentum attaches to
– Lesser curvature: superior, concave portion of the stomach where the lesser omentum attaches to from the liver
* Rugae/Gastric folds: capability for stomach to expand when full
What are the different gastric regions and their structures?
- Gastric regions
– Cardiac region: region closest to esophagus’ entry to stomach
– Fundic region/Fundus: dome-shaped region and is the superior part of the stomach
– Body: Majority region of the stomach, inferior of the cardiac and fundic region.
– Pyloric region/pylorus: narrow and is the part of the stomach that leads to the SI - Pyloric antrum: wider part of the pylus next to the body
- Pyloric sphincter: circular smooth muscle at the border of the stomach and SI controlling amount of chyme entering the SI
What types of cells are within the mucosa of the stomach and what do they produce?
Mucosa: made of simple columnar epithelium
» Mucous cells: secrete mucin to protect stomach mucosa from HCl and gastric enzymes
» G /enteroendocrine cells: secrete gastrin, hormone that stimulates chief and parietal cells secretion
» Parietal cells : secretes…
* HCl- : hydrochloric acid that denatures proteins to help chemical digestion and activates gastric enzymes
* Intrinsic factor: molecules that bind to vitamin B12 to help absorption in ileum
» Chief cells: secretes digestive enzymes
* Pepsinogen: inactive enzyme which becomes pepsin to digest proteins
* Gastric lipase: to digest triglycerides
What is different about the muscularis externa of the stomach compared to the rest of the alimentary canal?
Oblique layer: inner smooth muscle layer to help the churning and mixing by the stomach
What is the general functions of the small intestine and examples of what it does?
Functions:
– Mechanical digestion: segmentation
– Chemical digestion: secretions of digestive enzymes; most digestion occurs here
– Absorption: most of the absorption of nutrients and water occurs here
What are the regions of the small intestines?
- Duodenum
- Jejunum
- Ileum
What structures do you find in each region of the small intestines?
– Duodenum: short initial part of SI
* Greater/Major duodenal papilla: location where bile and pancreatic juice enter the duodenum
* Lesser/minor duodenal papilla: location where some pancreatic juice from the accessory pancreatic duct enters the duodenum
* Duodenal / Brunner’sglands/ submucosal glands: located in submucosal layer and makes alkaline mucus to protect duodenum from acidic chyme from stomach
– Jejunum: middle portion of the SI where most of the chemical digestion and absorption takes place
– Ileum: final part of SI
* Peyer’s patch/aggregated lymphoid nodules: located at the lamina propria and is a group of lymphatic nodules to defend against bacteria from the LI
* Ileocecal valve/sphincter: sphincter that regulates chyme going into LI
Name the different structures of the small intestine and their definitions
– Circular folds /plicae circularis: folds of the mucosal and part of the submucosal layers in the SI to help increase the surface area for absorption
– Villi: microscopic projections of the circular folds to increase surface area for absorption
– Microvilli /brush border: even smaller projections of a villus to increase surface area for absorption that is on the apical side of the simple columnar epithelial cells and contains brush border enzymes for final breakdown of nutrients
– Lacteals: lymphatic capillary for lipid absorption within each villus
– Intestinal glands/ intestinal crypts of Lieberkuhn: glands that dip into the mucosa layer.
– Cells:
* Absorptive cells: simple columnar epithelial cells that absorbs nutrients
* Goblet cells: that produce mucus to lubricate chyme and protect against acidic chyme
What are within the layers of the small intestine and their function?
- Mucosa
– Simple columnar epithelium:- Absorptive cells/enterocytes: for absorption and contain brush border enzymes to digest proteins, carbohydrates, and nucleic acids into really small molecules for absorption
- Tight junctions: between cells to prevent enzymes from going through
- Goblet cells: secrete mucus
– Lamina propria: - Lacteal: lymphatic capillary absorbs lipids
- Blood capillaries: absorb nutrients
- Submucosa
– Duodenal/Brunner glands: (duodenum) secretes bicarbonate-rich mucus to neutralize acidic chyme from the stomach
– Peyer’s patch: (ileum) large lymphatic nodules
What does the chyme become in the large intestine?
Becomes feces
What is the different between the large intestine and small intestine?
LI is large not in length but in diameter compared to SI.
What are the general functions of the large intestine?
– Propulsion: mass peristaltic movements occurs only a few times a day, otherwise really slow
– Limited chemical digestion due to the bacteria that reside here
– Absorb water, electrolytes, vitamins
– Stores feces
What are the regions of the large intestine and their associated structures and general functions?
– Cecum: initial part of LI where chyme from ileum goes through ileocecal valve
* Vermiform appendix: contains lymphatic nodules
– Colon: region between ileocecal junction and rectum
* Ascending colon: part of LI going superior from cecum
– Hepatic /right colic flexure: bend connecting ascending and transverse colon
* Transverse colon: part of LI goes transversely from the hepatic flexure to splenic flexure; where the transverse mesocolon connects to posterior abdominal wall
– Splenic/left colic flexure: bend connecting transverse and descending colon
* Descending colon: part of LI from splenic flexure to sigmoid colon
* Sigmoid colon: S-shaped part of LI that curves into pelvic cavity; where sigmoid mesocolon connects to posterior abdominopelvic wall
– Rectum : part of LI that connects sigmoid colon to anal canal and stores feces
– Anal canal: passes feces during defecation
* Internal anal sphincter: involuntary smooth muscle
* External anal sphincter: voluntary skeletal muscles
What are the large intestine structures and their general functions?
– Intestinal gland/crypts: Contains mucosa and submucosa layer; LI contains no villi
– Mucosa: simple columnar epithelium for absorption of water, electrolytes, and vitamins; and lots of goblet cells to help lubricate feces
– Muscularis externa: outer longitudinal layer does not completely surround cecum and colon
* Tenia coli: longitudinal bundles of smooth muscles that makes haustra
– Haustra: sacs that are formed by the taenia coli
– Epicolic appendages/ Omental appendices: lobules of fat hanging from the external surface
What is the general function of the liver?
– Produce bile: for emulsifcation of fats (mechanical digestion): breaking down fats to help chemical digestion
– Detoxify drugs
– Synthesize blood plasma proteins
– Breaks down damaged cells (ie: rbc’s)
– Breaks down glycogen into glucose
What are the lobes of the liver?
– Right
– Left
– Caudate lobe: adjacent to the IVC on the inferior side of liver
– Quadrate lobe: adjacent to the gallbladder on the inferior side of liver
What are the ligaments of the liver and their function/prior function?
- Falciform ligament: peritoneal fold securing liver to anterior wall
- Round ligament / Ligamentum teres: remnant of umbilical vein at the inferior portion of the falciform ligament
- Was the umbilical vein: blood returning to fetal heart from chorionic villi where it is oxygenated and gets nutrients
- Ligamentum venosum: remnant of ductus venosus on the inferior part of the liver
- Was the ductus venosus: carries the oxygen and nutrient picked up by the liver and pass it to IFC
What are the vessels coming through the porta hepatis and what do they carry?
– Hepatic portal vein: nutrient rich blood from stomach and intestines
– Hepatic artery proper: oxygen-rich blood from celiac trunk
– Common hepatic duct: bile exits from liver
What are within a hepatic lobule and their general functions?
– Hepatocytes: liver cells which make bile, detoxify, store excess nutrients, synthesize plasma proteins
– Vessels
* Portal triads : branch of hepatic portal vein, hepatic artery proper, and bile duct
– Hepatic portal vein: blood from GI tract, spleen, pancreas rich in nutrients but poor in oxygen is delivered to the liver to be detoxified
– Hepatic artery proper: delivers nutrients and oxygenated blood to liver
– Bile duct: drains bile from bile canaliculi to common hepatic duct
* Hepatic sinusoids : leaky capillaries where blood from branches of hepatic portal vein and hepatic artery proper mix and empty into…
* Central vein: drains blood from each lobule
* Hepatic vein: drains blood from central veins and empties into IVC
* Bile canaliculi: drains bile from hepatocytes into bile ductules
What is the blood flow through the hepatic portal system?
Inferior mesenteric vein
Splenic vein
Superior mesenteric vein
Hepatic Portal vein
Hepatic portal venules
Hepatic sinusoids
Central veins
Hepatic veins
Inferior vena cava
What is the flow of the biliary duct system?
- Hepatocytes secretes bile into…
- Bile canaliculi and then to…
- Bile ductules of the portal triad which empty into…
- R/L hepatic ducts when converge into…
- Common hepatic duct which then joins with
- Cystic duct that connects with the…
- Common bile duct or Gallbladder (stores and releases bile when fat is present in duodenum and releases it through the cystic duct)
- Cystic duct: which becomes the…
- Common bile duct which then connects with the main pancreatic duct to form the…
- Hepatopancreatic ampulla contains..
- Hepatopancreatic sphincter/sphincter of Oddi: smooth muscles that regulates the release of bile into the duodenum through the…
Major duodenal papilla into the duodenum
What are the regions of the pancreas?
– Head: wide and close to the duodenum
– Body: bulk of the pancreas
– Tail: narrow portion of pancreas towards the spleen
What is the general function of the gallbladder?
– Concentrate and store bile from the liver via cystic duct
– Bile acids /salts: steroids from cholesterol which helps the mechanical digestion of fats
What is the general function of the pancreas?
– Endocrine: produces hormones (ie: insulin,
glucagon)
– Exocrine: secretes digestive enzymes and bicarbonate
