A&P2.14 - The Digestive System Flashcards
Abdominopelvic Cavity
Made of 4 quadrants, list each and the organs they contain
URQ
- liver
- gall bladder
- part of small & lrg intestines
ULQ
- stomach
- spleen
- pancreas
- part of small & lrg intestines
LRQ + LLQ
- Part of small & lrg intestines
- urinary bladder, reproductive organs
Digestive System
Describe the gastrointestinal tract
- Continuous tube that’s open to outside of body
- begins with mouth and continues to pharynx, esophagus, stomach, sm intestine, lrg intestine, rectum and anus
- lined with mucous membrane
Digestive System - Functions
List the different functions of this system
- Ingestion
- Propulsion
- Mechanical digestion
- Chemical digestion
- Absorption
- Excretion
Digestive System - Functions
Describe ingestion
taking food in through mouth
Digestive System - Functions
Describe propulsion
- movement of food through digestive tract
- deglutition or peristalsis
Digestive System - Functions - Propulsion
Describe deglutition
swallowing
Digestive System - Functions - Propulsion
Describe peristalsis
slow, wave-like, involuntary movement using smooth muscle contraction
Digestive System - Functions
Describe mechanical digestion
- the physical breakdown of food into smaller particles
- 3 processes
** Mastication
** Churning
** Segmentation
Digestive System - Functions - Mechanical Digestion
Describe mastication
chewing
Digestive System - Functions - Mechanical Digestion
Describe churning
- alternating waves of peristalsis occuring only in the stomach
- used to swirl food particles in order to coat in digestive juices
Digestive System - Functions - Mechanical Digestion
Describe segmentation
slow form of peristalsis which keeps food in one area as it compresses and breaks it down
- allows more time for absorption
Digestive System - Functions
Describe chemical digestion
the addition of enzymes & digestive juices to chemically break down food
Digestive System - Functions
Describe absorption
- occurs through mucous membranes
- uptake of mechanical digestion by-products into blood (everything but dietary fat which is taken up by lacteals)
Digestive System - Functions
Describe defecation
elimination of indigestible solid food and waste prodcuts
Digestive System - Anatomy
List the different structures of this system
- mouth
- pharynx
- esophagus
- stomach
- small intestine
** liver
** gall bladder
** pancreas - large intestine (colon)
- rectum
Digestive System - Anatomy - Mouth
Accessory Organs
- teeth
- tongue
- salivary glands
Digestive System - Anatomy - Mouth - Accessory Organs
Teeth
grind- shred and tear food into small pieces
Digestive System - Anatomy - Mouth - Accessory Organs
Tongue
- moves food around mouth to help form a ball (bolus)
- made of skeletal muscle, taste buds and mucus producing glands
Digestive System - Anatomy - Mouth - Accessory Organs
Salivary Glands
- add digestive enzymes to food
- cleanse mouth
- moisten food
- some antibacterial properties
- 3 locations
** submandibular (underside of mandible)
** sublingual (under tongue)
** parotid (between masseter + skin anterior to ear)
Digestive System - Anatomy - Mouth
Functions
- ingestion
- mechanical digestion
- chemical digestion
- absorption
- deglutition
Digestive System - Anatomy - Mouth - Functions
Mechanical digestion
“muscles of mastication”
- temporalis
- masseter
- medial pterygoids
- lateral pterygoids
“muscles of chewing”
Digestive System - Anatomy - Mouth - Functions
Muscles of Mastication - Temporalis
covers temporal bone and runs to mandible
Digestive System - Anatomy - Mouth - Functions
Muscles of Mastication - Masseter
zygomatic arch and maxilla to mandible
Digestive System - Anatomy - Mouth - Functions
Muscles of Mastication - Medial pterygoids
- deep to masseter
- run from maxilla to medial mandible
Digestive System - Anatomy - Mouth - Functions
Muscles of Mastication - Lateral pterygoids
- deep to medial pterygoids
- run from sphenoid bone & articular disc + condyle of TMJ to mandible
Digestive System - Anatomy - Mouth - Functions
Chemical Digestion
- Enzymes mix w/ food in mouth
- 3 parts:
** enzymes
** carb digestion
** bolus
Digestive System - Anatomy - Mouth - Functions - Chemical Digestion
Enzymes
salivary amylase
Digestive System - Anatomy - Mouth - Functions - Chemical Digestion
Carb Digestion
salivary amylase breaks down complex carbs in mouth
Digestive System - Anatomy - Mouth - Functions - Chemical Digestion
Bolus
food mixed w/ saliva and shaped in ball to be swallowed
Digestive System - Anatomy - Mouth - Functions
Absorption
limited to sublingual medications like nitroglycerin (vasodilator)
Digestive System - Anatomy - Mouth - Functions
Deglutition
- swallowing
- involves 22 pairs of muscles
Digestive System - Anatomy
Pharynx
skeletal muscle tube that delivers bolus to esophagus
Digestive System - Anatomy
Layers of GI Tract Walls
- begins at esophagus
- run throughout large intestine adjusting as needed depending on the organ
- 4 layers:
** mucosa
** submucosa
** muscularis
** serosa
Digestive System - Anatomy - Layers of the Walls of the GI Tract
Mucosa
- innermost epithelial lining of GI tract
- in contact w/ food
- scretes mucus
- absorbs nutrients
- provides protection
Digestive System - Anatomy - Layers of the Walls of the GI Tract
Submucosa
moderately dense CT lyr containing blood vessels, nerves & lymphatics
Digestive System - Anatomy - Layers of the Walls of the GI Tract
Muscularis
- smooth ms layer responsible for peristalsis
- forms spheres in some regions
Digestive System - Anatomy - Layers of the Walls of the GI Tract
Serosa
- outermost layer of CT
- protective and anchors digestive organs to posterior abdominal wall
Digestive System - Anatomy
Esophagus
- ~10” long
- smooth ms tube that delivers bolus to stomach
- runs thru medistinum + diaphragm
- sphincter separates stomach & esophagus
Digestive System - Anatomy - Esophagus
Peristalsis
- moves bolus thru esophagus and into stomach
- can be reversed to vomit
Digestive System - Anatomy
Stomach
- ~10” long
- can be filled up to 1 gallon
- acts as storage tank for food
Digestive System - Anatomy - Stomach
Location
- ULQ
- anterior to spleen
- inferior to diaphragm
Digestive System - Anatomy - Stomach
Regions
- cardiac
- fundus
- body
- pylorus
Digestive System - Anatomy - Stomach - Regions
Cardiac Region
- location of cardiac sphincter
- uppermost region of stomach just adjacent to heart
Digestive System - Anatomy - Stomach - Regions
Fundus
- lateral “aterior arch” protion
- adptable/expandible portion
- where air/gas sits above juices
Digestive System - Anatomy - Stomach - Regions
Body
- the rest of the stomach
- produces gastric jucies
Digestive System - Anatomy - Stomach - Regions
Pylorus
- location of pyloric sphincter
- releases 3oz of fluid (thick, white paste) @ a time into small intestine
Digestive System - Anatomy - Stomach
Functions
- mechanical digestion
- chemical digestion
- absorption
Digestive System - Anatomy - Stomach - Functions
Mechnical Digestion
- churning of food to coat in digestive enzymes
** 3 layers of muscularis
–> compared to 1 layer in rest of GI tract
–> layers alternate directions to create churning
Digestive System - Anatomy - Stomach - Functions
Chemical Digestion
stomach lining creates digestive juices
- HCl
- Chyme
- Protein digestion
Digestive System - Anatomy - Stomach - Functions - Chemical Digestion
HCl
- hydrochloric acid
** very acidic
** pH = 1.5
—> creates environment where proteins can be digested and microorganisms are killed
Digestive System - Anatomy - Stomach - Functions - Chemical Digestion
Chyme
addition of digestive juices to bolus => paste
Digestive System - Anatomy - Stomach - Functions - Chemical Digestion
Protein Digestion
can only be done in an acidic environment which breaks the peptide bonds holding them together
Digestive System - Anatomy - Stomach - Functions
Absorption
limited here except for:
- aspirin
–> can irritate lining
- alcohol
–> effects felt quickly + disrupts protective lining
Digestive System - Anatomy - Stomach
Protective Stomach Lining
- thick mucosa layer
- tight junctions
–> “zipper” keeping lined cells together - regeneration of stomach lining every 3-6 days
Digestive System - Anatomy
Small Intestine
- responsible for 90% of all nutrient absorption
- food spends 3-6 hours here
Digestive System - Anatomy - Small Intestine
Location
- From pyloric sphincter to ileocecal valve
- all 4 quadrants of abpelvic cavity
- hangs curled up in abdominal cavity suspended from mesentery
Digestive System - Anatomy - Small Intestine
Regions
- duodenum
- jejunum
- ileum
Digestive System - Anatomy - Small Intestine - Regions
Duodenum
- where majority of absorption takes place
- ~1ft
- highest concentration of villi & microvilli
Digestive System - Anatomy - Small Intestine - Regions
Jejunum
- ~7ft
- less villi & microvilli => decreased absorption
Digestive System - Anatomy - Small Intestine - Regions
Ileum
- ~10ft
- even less villi & microvilli for absorption
- high mucus production to keep things moving as it dries due to water reabsorption
- ileocecal valve
Digestive System - Anatomy - Small Intestine - Internal Anatomy
Circular Folds
- cause food to swirl and remain in SI
- allows more nutrient absorption due to increase SA
Digestive System - Anatomy - Small Intestine - Internal Anatomy
Villi
- finger-like projections off of circular folds along inside walls of SI
- house microvilli
Digestive System - Anatomy - Small Intestine - Internal Anatomy
Microvilli
- tiny, hair-like projections of plasma membrane off of villi
- increase SA for better absorption
- give “brush-like” appearance to this tissue thus dubbed “brush border”
Digestive System - Anatomy - Small Intestine - Internal Anatomy
Lacteals
- present within circular folds
- absorb dietary fats and deliver them to the lymphatic flow
Digestive System - Anatomy - Small Intestine
Functions
- mechanical digestion
- chemical digestion
- absorption
- propulsion
Digestive System - Anatomy - Small Intestine - Functions
Mechanical Digestion
Segmentation
- a slow peristalsis that alternates to force material to slow down for better absorption
Digestive System - Anatomy - Small Intestine - Functions
Chemical Digestion
- proteins, fats & carbs
- brush border enzymes
Digestive System - Anatomy - Small Intestine - Functions
Chemical Digestion - Proteins, Fats & Carbs
all broken down @ this level
Digestive System - Anatomy - Small Intestine - Functions
Chemical Digestion - Brush Border Enzymes
- produced by brush border to break down all food types
- Enzymes (“-ase”) break everything dow into glucose
– Lactase => lactose
– Sucrase => sucrose
– Maltase => maltose
– Pepsin => peptides => amino acids
protein => peptide => amino acids
Digestive System - Anatomy - Small Intestine - Functions
Absorption
All nutrient types are absorbed here and brought to liver via hepatic portal circulation (except dietary fats)
Digestive System - Anatomy - Small Intestine - Functions
Propulsion
Peristalsis occurs here w/ slow segmentation for maximum absorption
Digestive System - Anatomy - Small Intestine
Accessory Organs
- liver
- gall bladder
- pancreas
Digestive System - Anatomy - Small Intestine - Accessory Organs
Liver
Has 200 functions
- only digestive function is to produce bile
Digestive System - Anatomy - Small Intestine - Accessory Organs
Liver -> Bile
yellow/green pigmented substance capable of breaking down fat into usable droplets
Digestive System - Anatomy - Small Intestine - Accessory Organs -Liver
Location
URQ inferior to diaphragm
Digestive System - Anatomy - Small Intestine - Accessory Organs - Liver
Structures/Functions
- hepatic duct
–> delivers bile to common bile duct - hepatic portal circulation
–> nutrients are absorbed from SI & delivered to liver via portal vein
Digestive System - Anatomy - Small Intestine - Accessory Organs
Gall bladder
- storage tank for bile
–> excess bile can back up into this and become dehydrated for future use - bile is delivered to common bile duct & secreted into SI
Dig. System - Anatomy - Smll Intestine - Accessory Organs - Gall Bladder
Location
Underneath the liver in URQ
Dig. System - Anatomy - Smll Intestine - Accessory Organs - Gall Bladder
Functions
- Cystic Duct
–> delivers excess bile into gallbladder - common bile duct
–> delivers bile from common hepatic & cystic ducts into SI
Dig. System - Anatomy - Smll Intestine - Accessory Organs
Pancreas
Largest endocrine gland
Dig. System - Anatomy - Smll Intestine - Accessory Organs - Pancreas
Location
- ULQ
- Posterior to stomach
- Extends posteriorly from SI
Dig. System - Anatomy - Smll Intestine - Accessory Organs - Pancreas
Products & Functions
- Hormones
–> produce insulin & glucagon to regulate blood sugar levels - digestive enzymes
–>create:
—>pancreatic amylase (carb digestion)
—>lipase (fat digestion)
—>trypsin (protein digestion) - pancreatic duct
–> delivers enzymes from pancreas into SI
Dig. System - Anatomy
Large Intestine
“colon”
Dig. System - Anatomy - Large Intestine
Location
- borders SI on 3 sides
- Runs from ileocecal valve to rectum
Dig. System - Anatomy - Large Intestine
Regions
- cecum
–> appendix - ascending colon
- transverse colon
- descending colon
- sigmoid colon
- rectum
- anus
–> internal sphincter
–> external sphincter
Dig. System - Anatomy - Large Intestine - Regions
Cecum –> Appendix
filled with lymthatic tissue
Dig. System - Anatomy - Large Intestine - Regions
Rectum
- distal region of LI
- signals urge to defecate
Dig. System - Anatomy - Large Intestine - Regions
Anus –> Internal & External Sphincters
- internal - automatically releases
- external - we control
Dig. System - Anatomy - Large Intestine
Functions
- Mechanical Digestion
- Chemical digestion
- Propulsion
- Defecation
Dig. System - Anatomy - Large Intestine - Functions
Mechanical Digestion
- very slow form of segmentation occuring in haustra
- allows time for bacterai to act on insoluble fiber
Dig. System - Anatomy - Large Intestine - Functions
Chemical Digestion
governed by gut flora (bacteria) which act on insoluble materials not acted on by SI => produce vitamins & methane gas (farts)
Dig. System - Anatomy - Large Intestine - Functions
Propulsion
very slow segmentation occurs every 30 minutes
Dig. System - Anatomy - Large Intestine - Functions
Defecation
Emptying of LI occurs 1-3x per day
Digestive Process
The food we eat is divided into 3 categories:
- starch/carbohydrates
- Fats/lipids
- Proteins
Digestive Process - Food Categories
Starch/Carbs
- Must be broken down into glucose to be used by the body as this is our primary fuel source (glucose)
–> Glucose is stored by liver and muscle as glycogen => eventually broken down into ATP - Begin digestion in the mouth from salivary amylase
- Not digested in the stomach
- Digestion finishes in SI from brush border enzymes and pancreatic enzyme amylase
Digestive Process - Food Categories
Fats/Lipids
- Must be broken down into fatty acids & glycerol to be used by the body
- Fats provide us with protection, insulation and an alternative fuel source
- Begin digestion in SI where bile from liver emulsifies into smaller fat droplets
- Lipase from pancreas breaks fown droplets in fatty acids and glycerol to be absorbed
–> some go to liver for synthesis
–> some absorbed by lacteals for drainage into bloodstream
—-> used by cells for fuel & plasma membranes
Digestive Process - Food Categories
Proteins
- must be broken down into amino acids to be used by the body
- proteins are used as building blocks for the body providing tissue maintenance and growth
- Break down begins in stomach as broken down into peptides by enzyme pepsin
- SI, peptides broken into amino acids by brush border enzyme peptidase and pancreatic enzyme trypsin
- AAs absorbed and sent to liver for use
Digestive System
Vitamins
- organic (carbon based) compounds essential for metabolic function
- the only vitamin we produce is vitamin D
- water soluble vs fat soluble
Digestive System - Vitamins
Water Soluble
can dissolve and be excreted in water
- vitamins B & C
Digestive System - Vitamins
Fat Soluble
Dissolbe in fat & can accumulate
- vitamins A, D, E & K
Digestive System
Minerals
Inorganic compounds essential for metabolic function
- must be retrieved from diet
–> magnesium
–> zinc
–> selenium
Digestive System
Water distribution and intake
- intake ~40% from food
- 2/3 intracellular vs 1/3 extracellular at a given time
Digestive System
Metabolism
the sum of all chemical processes within a living organism needed to maintain life
- anabolism
- catabolism
Digestive System - Metabolism
Anabolism
building molecules
AA -> peptides -> proteins
Digestive System - Metabolism
Catabolism
breaking down molecules
proteins -> peptides -> amino acids