Digestive System Flashcards
Name the 6 functions of the digestive system
- ingestion
- digestion
- secretion
- motility [along tract]
- absorption
- elimination
Name the 6 body parts within the gastrointestinal tract.
1) Oral cavity
2) Pharynx
3) Esophagus
4) Stomach
5) Small Intestine
6) Large Intestine
Name the 4 digestive glands/ organs.
1) Salivary glands
2) Gall bladder
3) Pancreas
4) Liver
What is the name of the “back exit” leading to the oral pharynx?
Fauces
What is the mucosal fold that anchors the most moveable part of the tongue [midline]?
Lingual frenulum
Where does the parotid gland (largest salivary gland) open into?
Parotid papilla @ sides of cheek
What is the function of the hard palate?
- separates nasal cavity from oral cavity
- palatine bone, palatine process
What is the function of the soft palate?
- separates nasal pharynx from oral pharynx
- palatine muscles
What is the function of the uvula?
- dangly part from roof of soft palate
- prevents food from unintentionally leaving oral cavity
Where are the palatine/ lingual tonsils located?
palatine = lateral walls of oral cavity lingual = posterior to tongue
What is the area between the teeth, lips, and cheek known as?
Vestibule
What are the openings present on the underside of the tongue known as?
Submandibular duct (opening to submandibular glands)
Name the 4 extrinsic mm. of the tongue.
- hyoglossus m.
- styloglossus m.
- genioglossus m.
- palatoglossus m.
Name the 3 intrinsic mm. of the tongue.
- superior longitudinal m.
- inferior longitudinal m.
- vertical/ transverse mm.
What is the function of the tongue?
- movement of food bolus during mastication
- speech
This type of papillae is most numerous and is found all throughout the tongue. It is known for its rough surface, often keratinized; however does not have taste buds.
Filiform papillae
Name the 4 types of papillae found on the tongue.
- vallate (swirl-shaped)
- foliate (folds - lateral side)
- filiform (thruout; keratinized; no taste buds)
- fungiform (tip + sides)
What are the 3 parts of a tooth?
- crown (exposed)
- neck
- root
What supplies the dentin within a tooth the materials for growth?
Pulp - also contains nerve endings, venous drainage, connective tissue, etc.
Which parts of a tooth connect and position the root to the alveolar bone within the jaw?
- cementum (more medial to tooth)
- periodontal ligament (fibrous connective tissue directly b/n cementum and alveolar bone —> contains blood vessels + nerves)
Which teeth only have one root?
- central/ lateral incisors (anterior medial)
- cuspid (canines - pointy)
Which teeth have 2 roots?
- pre-molars (1st + 2nd premolar on each side)
Which teeth have 3 roots?
- molars (1st - 3rd molar on each side)
Name the 3 parts of the pharynx from superior to most inferior.
- NASOPHARYNX (auditory tube opens into this)
- OROPHARYNX (directly behind oral cavity)
- LARYNGOPHARYNX
Name the 3 pharyngeal mm. that help w/ swallowing.
superior/ middle/ inferior pharyngeal constrictors
Name the 4 layers of the GI tract from deepest to most superficial.
- mucosa (epithelium/ lamina propria/ muscularis mucosa)
- submucosa
- muscularis externa (circular/ longitudinal mm)
- serosa/ mesentery
What are the two movements created by the GI tract to propel the bolus?
- peristalsis (both muscles used)
- segmentation (mix contents; no net movement; mainly circular m.)
Name the different types of mesenteries.
- intraperitoneal (completely covered)
- retroperitoneal (primary/ secondarily)
Describe the muscle that makes up the esophagus throughout its journey to the stomach.
- top 1/3: muscularis externa [skeletal muscle = conscious control]
- middle 1/3 = mix
- bottom 1/3: smooth muscle [no control]
What controls the opening of the esophagus to the stomach?
- cardiac sphincter
- opens b/c of peristalsis
Describe the epithelium of the esophagus.
Abrasion-resistant non-keratinized stratified squamous epithelium
What are the functions of the omentum?
- large pouch of mesenteries
- lipid deposition = temperature control
- immunological function
- has blood, nerve, lymphoid tissue
Describe the layers of the stomach wall from superficial to deep.
- longitudinal
- circular
- oblique
What is the function of enteroendocrine cells?
G-cells secrete GASTRIN (stimulates parietal + chief cells).
What is the function of chief cells?
- secretes PEPSINOGEN (activated by HCl to break down proteins)
What is the function of parietal cells?
- secretes HCl [+ intrinsic factor for Vitamin B12] –> activates pepsinogen+ digestion
What is the function of mucus cells found within the gastric gland (stomach) mucosa?
- secretes mucous (for protection and lubrication of bolus)
Name the 3 regions of the small intestine in proper order.
- duodenum
- jejunum
- ileum
What is the average length and SA of the small intestine?
length = 6m (20 ft) SA = 2,000 sq ft
Where does the majority of digestion and absorption occur within the SI?
jujenum
Which part of the SI receives secretions from the pancreas and gall bladder?
duodenum
further digestion of fat, protein, sugar
How many times do plicae circulares increase the SI’s SA by?
3x
In an area with villi + crypts (glands)/ microvilli, how many times is the SA increased by?
10x (villi + crypt)
20x (microvilli)
= 200x total
What is a glycogalyx?
sugar + protein substances create a mesh of digestive cells - captures digestive enzymes + food = DIGESTION!
(found on microvilli)
What are the 4 types of cells found within the villar epithelium?
- paneth cell (lysozyme)
- enteroendocrine cell (serotonin)
- goblet cell (mucous)
- microvilli (absorptive)
Where do proteins and sugars get absorbed into within the villi?
- into capillary network (thru epithelium)
Where does fat (fatty acids, mono/triglycerides) get absorbed into within the villi?
- into lacteals [lymphatic vessels] as chylomicrons (droplet of fat present in lymph)
Name 3 major digestive glands.
1) salivary glands
2) pancreas
3) liver + gallbladder
What is the function of the ileocecal valve?
Connects SI + LI
List the 4 regions of the large intestine (in order).
- ascending colon
- transverse colon
- descending colon
- sigmoid colon
What is another name for the right colic flexure (bend)?
hepatic flexure (liver)
What is another name for the left colic flexure?
splenic flexure
What are the functions of the large intestine?
- reabsorbs H2O + electrolytes
- absorbs vitamins produced by colonic bacteria (K, B12)
- compacts + stores feces
What are taenia coli?
3 longitudinal ribbons of smooth muscle along colon - contract lengthwise to produce haustra (bulges) to push waste bolus
Name the 2 types of cells found within the intestinal crypt’s epithelium.
- goblet cell (mucus)
- absorptive cell (H2O, vitamins)
+ lymphoid nodules under epithelium
This anal sphincter is controlled by the autonomic nervous system (smooth muscle control).
Internal sphincter
This anal sphincter can be consciously controlled (skeletal muscle).
External sphincter
List some secretions by the salivary glands.
- serous
- mucous
- amylase (carb digestion)
- antibodies
- chemicals stimulating taste buds
Name the 3 glands that make up the salivary glands.
- parotid gland (largest - by ear; 1 duct)
- submandibular (floor of mouth; 1 duct)
- sublingual (under tongue; multiple ducts)
What is the difference b/n serous and mucus secretions?
Serous - more water, dissolves food
Mucus - coats bolus ; have mucin
What kind of secretions do the parotid glands release?
- serous
- amylase
- 25%
What kind of secretions do the sublingual glands release?
- mucous
- 5%
- multiple ducts
What kind of secretions do the submandibular glands release?
- serous & mucous
- 70%
What system controls the secretion of salivary glands?
- parasympathetic = secrete
- sympathetic = inibit
What stimulates the secretion from salivary glands?
- taste/ sight/ smell/ thought of food
- presence of food in mouth
Which organ does the pancreas secrete its digestive enzymes into?
small intestine
What is the function of the bicarbonate buffer that the pancreas secretes?
- neutralizes acidic chyme from stomach
- establishes pH for pancreatic digestive enzymes
Pancreatic acinus ducts are fed by two types of cells. What are they and what do they secrete?
1) Acinar cells - active digestive enzymes + zymogens (inactive enzymes later activated in SI)
2) Centroacinar cells - bicarbonate buffer (neutralizes acidic chyme –> dissolves digestive enzymes, regulates zymogens)
T/F
Pancreatic duct merges with common bile duct to enter duodenum at the ampulla of Vater.
True.
T/F
The accessory pancreatic duct only contains pancreatic secretions and empties superior to the ampulla Vater.
True.
T/F
The liver is the largest GLAND in the body.
True.
T/F
The liver falls into all three hypochondriac/ epigastric regions.
False.
The liver sits within the right and central hypochondriac region.
T/F
The stomach is attached to the lesser omentum, which falls posterior of the liver.
False.
The liver and stomach are both attached by the lesser omentum. HOWEVER - the liver is attached on its dorsal wall.
The liver is supplied by vessels that travel through the lesser omentum. Name these “3 amigos”.
- proper hepatic artery (oxygenated)
- portal vein (deoxygenated)
- common bile duct (from gallbladder)
What are the three major functions of the liver?
- metabolic regulation
- hematological regulation
- synthesis + secretion of bile
Define the metabolic regulation done by the liver.
- carbohydrates – > stores glucose as glycogen + interconverts glucose
- lipids –> stores + metabolizes triglycerides (oxidizes TAGs from lymphatic system) –> MAKES CHOLESTEROL
- amino acids –>deamination + transamination ; ammonia -> urea
- *inactivates toxic compounds + drugs from intestine
Describe the hematological regulation of the liver.
- destroys aged RBC
- produces + secretes components of blood plasma proteins
Explain the blood flow to the liver.
- hepatic artery (+O2) =30%
- hepatic portal vein (-O2, nutrient rich) = 70%
The hepatic portal vein is formed by confluence of which 3 veins?
- inferior mesenteric (LI)
- superior mesenteric (SI, LI)
- splenic veins
T/F
All blood drainage from intestines flows to the liver before returning to the heart.
True - as deoxygenated blood.
+O2 & -O2 blood mix in liver –> exit liver thru hepatic veins to inferior vena cava.
Lipids delivered directly thru lymphatic system.
What is are the specialized macrophages called within the liver that carry out the destruction of outdated RBC and pathogens?
Kupffer cells
What is the name of the functional unit of the liver?
Liver lobule - @ centre is the central vein (carried to hepatic vein) – > hexagonal grouping of cells surrounded by connective tissue
T/F
Hepatocytes (epithelial cells of the liver) sit on top of each other, creating wall/ plate within space in b/n (sinusoids) where [-O2/+O2) mix.
True.
What is an individual liver cell known as?
Hepatocyte
What is the function of hepatocytes?
Take substances up from blood and secrete substances into blood
What is name of the space of exchange between the hepatocyte and blood vessel (sinusoid) endothelium?
Space of Disse
ENDOCRINE FUNCTION
Where does the bile produced by liver cells drained into?
bile canaliculi
THINK: bile canal
What is the direction of blood flow within the lobule?
Periphery towards central vein
What is the function of bile (synthesized by liver)?
- bile salts emulsify fats in intestine
- emulsification necessary for digestion
Where does the bile produced get stored?
Bile transferred to gall bladder for storage
How are bile canaliculi formed?
Two hepatocytes side by side (same plane) - two haves of canaliculi form large calibre bile duct for drainage
(EXOCRINE FUNCTION)
Bile vs blood flow within the lobule?
Bile: centre to periphery
Blood: periphery to centre
What triggers the release of bile from the gall bladder?
Presence of chyme in duodenum
What is the name of the sphincter that controls how much bile gets released into the duodenum?
hepatopancreatic sphincter
Which hormone induces the relaxation of the hepatopancreatic sphincter and contraction of the gallbladder (releasing bile)?
cholecystokinin (CCK)
