Human Anatomy CH 23 Flashcards
What 2 groups are organs of the digestive system divided into? What organs are included in each group?
- Alimentary canal - Mouth, pharynx, esophagus, stomach, small intestine, and large intestine
- Accessory digestive organ - Teeth, tongue, gallbladder, salivary glands, liver, and pancreas
Accessory organs are connected to the alimentary canal by ______. What do secretions do?
- Ducts
- Contribute to breakdown of foodstuffs
4 lines divide the abdominal wall into _______ regions
9
What is the vertical line, superior horizontal line, and inferior horizontal line respectively called? What does the latter two connect?
Midclavicular Line - Vertical line
Subcostal Plane - Superior horizontal line
Transtubercular Plane - Inferior horizontal line
Subcostal plane connects inferior points of costal margin.
Transtubercular plane connected tubercles of iliac crests.
What is a serous membrane called?
Peritoneum
What surrounds the digestive organs?
Visceral peritoneum
What lines the body walls?
Parietal peritoneum
What is a slitlike potential space called?
Peritoneal cavity
What is the double layer of peritoneum called?
Mesentery
What are the 3 main general functions of the Mesentery?
- Holds organ in place
- Sites of fat storage
- Provides a route for circulatory vessels and nerves
What 2 parts fall under the Ventral mesenteries? What are their functions?
- Falciform Ligament - Binds anterior part of liver to anterior abdominal wall
- Lesser Omentum - Attaches liver to lesser curvature of stomach
What 3 parts are included under the Dorsal mesenteries? What are their functions?
- Greater Omentum - Connects greater curvature of stomach to posterior abdominal wall
- Transverse mesocolon - Holds transverse colon in place
- Sigmoid mesocolon - Connects the sigmoid colon to posterior pelvic wall
What is referred to as a “fatty apron”?
Greater Omentum
What are Peritoneal organs? Where are retroperitoneal organs located?
- Digestive organs that keep their mesentery
- Located behind the peritoneum
Where is Secondarily Retroperitoneal Organs initially formed? What do they become?
- Initially formed within peritoneum
- Become retroperitoneal and fuse to posterior abdominal wall
What occurs in the mouth?
Ingestion
What is the movement of food called?
Propulsion
What is the major means of propulsion called? Where does this occur/what happens while it’s occurring?
Peristalsis
Adjacent segments of the alimentary canal relax and contract
Mechanical breakdown is the term for what? What are some examples of this?
Preparation of food for digestion
Chewing, churning good in stomach, segmentation
What is the term for rhythmic local constrictions of the intestine?
Segmentation
Chemical breakdown is the term for what? Where are the 3 places this occurs?
Complex molecules broken down to chemical components
1. Mouth
2. Stomach
3. Small intestine
The transport of digested nutrients is called?
Absorption
Elimination of indigestible substances as feces is called?
Defecation
What same 4 layers appear from the esophagus to the anus in regards to the alimentary canal wall?
- Mucosa
- Submucosa
- Muscularis Externa
- Serosa
Name each of the 4 layers from innermost to outermost
- Mucosa - Innermost
- Submucosa - External to mucosa
- Muscularis Externa - External to submucosa
- Serosa - Outermost layer
What 3 things is the mucosa consisted of?
- Epithelium
- Lamina propria
- Muscularis mucosae
What does the submucosa contain?
Blood, lymphatic vessels, and nerve fibers
What two layers does the muscularis externa contain? Which one is the innermost and which one is the outermost?
- Circular muscularis - Inner layer
- Longitudinal muscularis - Outer layer
What is another name/word for the serosa?
Visceral peritoneum
Where is smooth muscle tissue typically found?
Walls of viscera
List 3 qualities of smooth muscle tissue within the digestive system
- Fibers are elongated
- Have one centrally located nucleus
- Grouped into sheets
What 2 layers are made up of smooth muscle tissue? Describe their location in relation to the organ they surround
- Longitudinal muscularis - Parallel to long axis of organ
- Circular muscularis - Deeper layer, fibers run around circumference of organ
What are the 3 steps to smooth muscle contraction?
- Myofilaments operate by interaction with cytoskeleton
- Sliding myofilaments shorten the muscle cell by pulling on cytoskeleton
- Entry of Ca2+ into sarcoplasm stimulates contraction
Dense bodies correspond to _______?
Z-discs of skeletal muscles
What is muscle contraction like? What is smooth muscle contraction resistant to?
Slow and sustained
Resistant to fatigue
How long do smooth muscle of arteries and visceral organs have to sustain themselves?
Contraction must be sustained over long periods of time
How long does smooth muscle contraction take to decompress?
Takes 30x longer to contract and relax
What are the energy requirements for smooth muscle contraction? Why is it this way?
Energy requirements are low, because mitochondria are not abundant
What innervates smooth muscle?
ANS (Autonomic Nervous System)
What is single-unit innervation?
HINT: Name 2 facts and compare it to multi-unit innervation
Few fibers per sheet innervated and sheet of smooth muscle contracts as a unit
What is multi-unit innervation? What muscles are innervated this way?
Each smooth muscle cell innervated
1. Iris of eye
2. Arrector pili muscles
Where does the myenteric nerve plexus located? What does it control?
- Between circular and longitudinal muscularis
- Controls peristalsis and segmentation
Where does the submucosal nerve plexus lie? What is its function?
- Lies in submucosa
- Signals glands to secrete
Nerve plexuses are innervated by what 3 fibers?
- Sympathetic motor fibers
- Parasympathetic motor fibers
- Visceral sensory fibers
What lines the oral cavity?
Mucosa-lined cavity
What type of tissue is the mucosal layer consisted of? The mucosal layer of the oral cavity also includes ______
- Stratified squamous epithelium
- Lamina propria
What 2 muscles form the lips and cheeks?
- Orbicularis oris
- Buccinator
What connects the lips to the gum?
Labial frenulum
What forms the roof of the mouth?
Palate
What are the 2 boundaries of the fauces?
- Palatoglossal arches
- Palatopharyngeal arches
What are the 2 main functions of the tongue within the digestive system?
- Grips food and repositions it
- Helps form some consonants
What is the tongue made of?
Interlacing fascicles of skeletal muscles
What kind of muscles are within the tongue? What about those external to the tongue?
- Intrinsic muscles - within tongue
- Extrinsic muscles - external to the tongue
What secures the tongue to the floor of the mouth?
Lingual frenulum
What 3 papillae make up the tongue papillae? Which one has no taste buds?
- Filiform papillae - no taste buds
- Fungiform papillae
- Vallate papillae
What marks the border between the mouth and pharynx?
Sulcus terminalis
What lines the posterior 1/3 of the tongue? Where does it lie?
Lingual tonsil in oropharynx
What are the first 20 teeth called? When do they first appear?
Deciduous teeth; 6 months of age
What are the 32 teeth called? When do they first appear?
Permanent teeth; most erupt by end of adolescence
What does the dental formula represent?
Shorthand formula for adult dentition that indicates number and position of teeth
The upper teeth are innervated by what nerves?
Superior alveolar nerves branching from maxillary division of CN V
The lower teeth are innervated by what nerves?
Inferior alveolar nerves branching from mandibular branch of CN V
What is the arterial supply to the teeth?
Superior and inferior alveolar arteries branching from maxillary arteries
What is the term for the exposed surface of a tooth?
Crown
What is the term for the part of the tooth in the tooth socket?
Root
What is the outer layer of the tooth called?
Enamel
What layer lies beneath the enamel?
Dentin
What is the center of the tooth called?
Pulp cavity
What is another name for the salivary/mucous glands?
Compound tubuloalveolar glands
What are the 3 salivary glands? Where do they lie and what type of cells do they contain?
- Parotid glands - contain serous cells | parotid duct is parallel to zygomatic arch
- Submandibular glands - Lies along medial surface of mandible
- Sublingual glands - contain primarily mucous cells | lie in floor of oral cavity
What 2 parts of the digestive system does the pharynx contain? What are their functions and what type of tissue are they lined with?
- Oropharynx
- Laryngopharynx
Passages for air and food
Lined with stratified squamous epithelium
The external muscle layer of the pharynx consists of what?
Superior, middle, and inferior pharyngeal constrictors
In gross anatomy, what is another name for the esophagus?
Muscular tube
Where does the esophagus begin? What does it join?
Begins as continuation of the pharynx and joins the stomach inferior to the diaphragram
What closes the lumen to prevent stomach acid from entering the esophagus?
Cardiac sphincter
What type of tissue makes up the epithelium of the esophagus?
Stratified squamous epithelium
What does the cardiac sphincter do?
Closes lumen to prevent stomach acid from entering the esophagus
When the esophagus is empty, where is the mucosa and submucosa located?
In longitudinal folds
What is another word for salivary/tubuloalveolar glands?
Mucous glands
The muscularis externa is consisted of what type of muscle for which of its sections (respectively)?
- Skeletal muscle - First 1/3
- Mixture of skeletal and smooth muscle - Middle 1/3
- Smooth muscle - Inferior 1/3
What is the most external layer of the esophagus called?
Adventita
What is the function of the stomach? How long does food remain in it?
Site where food is churned into chyme; food remains for approximately 4 hours
What is secreted to begin protein digestion? What conditions does it function under?
Secretion of pepsin begins protein digestion; functions under acidic conditions
What are the 4 regions of the stomach?
- Cardial part
- Fundus
- Body
- Pyloric part
The muscularis of the stomach has what 3 layers?
- Circular layer
- Longitudinal layer
- Oblique layer
What type of tissue makes up the epithelium of the stomach?
Simple columnar epithelium
The mucosa of the stomach is dotted with what? What is deep to it?
Gastric pits; gastric glands deep to gastric pits
The gastric glands of the fundus and body have what 3 types of cells? What does each one secrete?
- Mucous neck cells - secrete special mucus
- Parietal (oxyntic) cells - secrete hydrochloric acid and gastric intrinsic factor
- Chief (zymogenic) cells - secrete pepsinogen
Pepsinogen is activated to become what? When does it activate?
Activated to pepsin when it encounters acid in the gastric glands
What is the longest portion of the alimentary canal?
Small intestine
The small intestine is the site of __________?
Most enzymatic digestion and absorption
What 2 fibers is the small intestine innervated from? Which nerves do these fibers come from?
- Parasympathetic fibers from vagus nerve
- Sympathetic fibers from thoracic splanchnic nerves
What 2 ducts enter the duodenum? What does the duodenum receive?
- Main pancreatic duct
- Common bile duct
Receives digestive enzymes and bile
What do sphincters do?
Control entry of bile and pancreatic juices
What are transverse ridges of the mucosa and submucosa called?
Circular folds
What are villi? What type of tissue are they covered in?
Simple columnar epithelium
What do microvilli do?
Further increases surface area for absorption
Where do epithelial cells secrete intestinal juice?
Intestinal crypts
What are the 3 main cells found within the intestinal wall? What are their functions?
- Absorptive enterocytes - uptake digested nutrients
- Goblet cells - secrete mucus that lubricates chyme
- Enteroendocrine cells - secretes hormones
What increases surface area for absorption?
Microvilli
What is the main function of the large intestine?
Absorb water and electrolytes
What is digestion in the large intestine done by and what does the digested residue contain?
Small amount of digestion by bacteria, with digested residue containing few nutrients
Digested residue is forced towards where via what kind of movement?
Mass peristaltic movements force feces towards rectum
What is the thickening of longitudinal muscularis within the large intestine called?
Teniae coli
The puckering within the small intestine is created by? The subsequent created segments are called?
Teniae coli; Haustra
What are fat-filled pouches of visceral peritoneum called?
Epiplotic appendages
What is the blind pouch that is the beginning of the large intestine?
Cecum
What type of tissue is the anal canal lined with?
Stratified squamous epithelium
What part of the large intestine contains lymphoid tissue and neutralizes pathogens?
Appendix
What descends along the inferior half of the sacrum?
Rectum
What is the arterial supply for the first half of the large intestine?
Superior mesenteric artery
What nerves does the first half of the large intestine sympathetic and parasympathetic (respectively) innervate from?
- Sympathetic - superior mesenteric and celiac ganglia
- Parasympathetic - vagus nerve
What is the arterial supply for the distal half of the large intestine?
Inferior mesenteric artery
What nerves does the distal half of the large intestine sympathetic and parasympathetic (respectively) innervate from?
- Sympathetic - inferior mesenteric and hypogastric plexuses
- Parasympathetic - pelvic splanchic nerves
What are 2 distinct features of the large intestine?
Villi are absent and it contains numerous goblet cells
Intestinal crypts contain?
Simple tubular glands
What type of tissue is the large intestine lined with? Where does it change and what does it change into?
Simple columnar epithelial tissue changes at the anal canal into stratified squamous epithelium
What is the largest gland in the body? How many functions does it have? What are 3 of those functions?
- Liver
- Over 500 functions
- Digestive function, bile production, and many metabolic functions
What are functional cells of the liver called?
Hepatocyte
The portal triad is composed of what 3 parts?
- Bile duct tributary
- Branch of hepatic portal vein
- Branch of hepatic artery
What cells destroy bacteria in the liver?
Hepatic macrophages
Name 7 functions of hepatocytes
- Rough ER manufactures blood proteins
- Smooth ER produces bile salts, detoxifies poisons
- Peroxisomes detoxify poisons (alcohol)
- Golgi apparatus packages secretory products
- Mitochondria provide energy for liver processes
- Glycosomes store sugar
- Great capacity for regeneration
What is the function of the gallbladder?
Stores and concentrates bile
Where does the gallbladder expel bile into? The bile does what to fats?
Expels bile into duodenum
Bile emulsifies fats
What is released from enteroendocrine cells in response to fatty chyme?
Cholecystokinin
What are the 2 endocrine functions of the pancreas?
- Produces insulin and glucagon
- Regulates blood sugar
What is the exocrine function of the pancreas?
Produces most enzymes that digest food in the small intestine
How would you describe the pancreas?
HINT: Has to do with approximate location
Secondarily retroperitoneal
What extends the length of the pancreas?
Main pancreatic duct
The main pancreatic duct joins the bile duct to form? Where does this empty into?
Forms hepatopancreatic ampulla which empties into the duodenum
Where is the pancreas’ arterial supply?
Hepatic, splenic, and superior mesenteric arteries
EXOCRINE FUNCTION: What cells make, store, and secrete pancreatic enzymes? Where are these enzymes activated?
Acinar cells
They are activated in duodenum
What are peptic ulcers?
Erosions of the mucosa of a region of the alimentary canal
Where do gastric ulcers occur?
Pyloric region of stomach
What occurs in the duodenum of the small intestine?
Duodenal ulcers
Peptic ulcers are caused by what bacteria? What is an important trait of this bacteria?
Helicobacter pylori
Acid-resistant
Where does H. pylori bind to? What does this cause?
Binds to gastric epithelium
Induces oversecretion of acid and inflammation
What are 2 disorders that are the inflammation of the intestinal wall?
- Crohn’s disease
- Ulcerative colitis
What disorder has jaundice and flulike symptoms? What are the 4 major types of this disease?
Viral Hepatitis
Type A, B, C, and G
What happens with the pancreas when you have cystic fibrosis?
Pancreatic ducts become blocked with mucus
What 2 things occur as a result of mucus blocking your pancreatic ducts?
- Prevent pancreatic juices from entering small intestine
- Malabsorption of fats and other nutrients
When is the alimentary canal formed? What is enclosed when it forms?
Formed in week 3; encloses tubular portion of yolk sac
What are the 3 regions of the gut?
Foregut, midgut, and hindgut
What is the landmark that divides the 3 gut regions?
Vitelline duct
What 2 symptoms can occur in middle age?
Gallstones and ulcers
What 4 things occur in old age as the activity of digestive organs decline?
- Fewer digestive juices and enzymes are produced
- Absorption of less efficient
- Dehydration of fecal mass leads to constipation
- Diverticulosis and cancer of digestive organs
