Aulner Digestive Sysem Flashcards
Functions of digestive system
Ingestion
Mechanical digestion
Chemical digestion
Absorption
Secretion
Defecation/elimination
Mechanical or chemical digestion?
Mastication (chewing), mixing, churning and propulsion (moving food around). Physical changes that break it up, but doesn’t change what it is.
-increases exposed surface area of food so chemical digestion can happen faster
Mechanical digestion
Mechanical or chemical digestion?
Breaking apart chemical bonds, taking larger molecules and breaking them into smaller ones to be absorbed in blood (happens in small intestine) (job of digestive enzymes)
Chemical digestion
Movement of nutrient molecules through digestive wall into blood or lymphatic system is
Absorption
Adding some product to food as it passes is
Secretion
Getting rid of material we can’t digest or don’t have time to digest is
Defecation/elimination
Digestive organs are
Oral cavity
Pharynx
Esophagus
Stomach
Small intestine
Large intestine
Accessory organs are
Salivary gland
Liver
Pancreas
Gallbladder
Spit on food as it goes by but doesn’t touch the food
Order the organs of the alimentary canal/digestive tract in order
Oral cavity (mouth)
Pharynx (throat)
Esophagus
Stomach
Small intestine
Large intestine
Rectus and anus
Involuntary contraction and relaxation of longitudinal and circular muscles throughout the digestive tract
Peristalsis
Sheets of serosa (sheets of peritoneum)
Mesenteries
Layers that make up digestive tract
Mucosa
Submucosa
Muscularis
Serosa
Layer touching food with epithelium in it (modified by organ)
Mucosa
Areolar and dense irregular connective tissue and glands (tiny glands inside epithelium-lymphoid nodule)
MALT= mucosa associated lymphoid tissue
Submucosa
2 layers of smooth muscle cells (longitudinal and circular layer)
Muscularis
Mucosa of oral cavity is
Stratified squamous epithelium
Narrow space between teeth and gums and internal surfaces of teeth and gums is
Vestibule
Allows us to breath and chew at the same time (mechanical digestion) is
Hard palate
When swallowing both moves posteriorly to prevent food from entering the nasal cavity
Soft palate and uvula
Baby teeth”
20- deciduous teeth
4 incisors
2 canines
4 molars in both mandible (bottom) and maxilla (top)
Primary dentin / deciduous teeth
Situated above primary dentition in maxilla and below in mandible. When a child is about 6 yrs old secondary teeth enlarge pressing on deciduous teeth causing them to fall out
32 permanent teeth
4 incisors
2 canines
4 pre-molars
6 molars
Secondary dentin/permanent teeth
Wisdom teeth erupt around ages…
17-21
Crown made of calcium hydroxyapatite crystals with only a small amount of organic material. This makes it the hardest substance in body, allowing it to endure the forces that accompany chewing
Enamel
Made of half calcium hydroxyapatite crystals and half organic compounds like collagen fibers. Hard like bone and cements the teeth in place
Cementum
Why masticate (chew)??
Increases surface area of food so chemical digestion can happen faster
Incisors are used for
Canines are used for
Molars are used for
Cutting
Tearing
Chewing
Secondary dentition (permanent teeth)
Maxillary (top) And mandible (bottom)
Central and lateral incisors
Canines
Pre molars
Molars
Maxillary (top)
-central incisors age (7-8yrs)
-lateral incisors (8-9yrs)
-canines age (11-12yrs)
-premolars age (10-12yrs)
-molars age (6-13yrs)
Mandible (bottom)
-molars (6-13yrs)
-premolars (10-12yrs)
-canines (9-10yrs)
-lateral incisors (7-8yrs)
-central incisors (6-7yrs)
Phases of deglutition (swallowing)
1) voluntary phase
2) pharyngeal phase
3) esophageal phase
(Oral phase) the tongue pushes the bolus toward oropharynx (controlled by skeletal muscle fibers) the tongue pushes the bolus up against the palate and backwards toward the pharynx
Voluntary phase (1st phase of deglutition)
(Reflexive act) the bolus enters oropharynx, the soft palate and epiglottis seal off the nasopharynx and larynx. (Bolus is shoved back into pharynx, pharynx has stretch receptors that tell it bolus is there. A reflexive nucleus In medulla oblongata that sends signals telling pharyngeal muscles to contract at same time larynx is elevated and closes off epiglottis. (Takes one second to happen)
Pharyngeal phase (2nd phase of deglutition)
Peristaltic waves move the bolus down the esophagus to the stomach (takes about 5 seconds to go from pharynx to stomach)
Esophageal phase (3rd phase of deglutition)
Function of esophagus
The food tube, moves food and liquids from mouth to stomach
Mucosa of esophagus is
Stratified squamous epithelium
Functions of stomach
Secretion
Propulsion
Digestion
Normally the cardiac sphincters remains closed except during swallowing, when this mechanism fails acidic chyme from stomach regurgitates into esophagus which may lead to pain, difficulty swallowing, vocal cord damage or respiratory problems, esophageal cancer
GERD
Mucosa of stomach is
Simple columnar epithelium and has gastric pits
Gastric pits are
Permanent Inward projections of mucosa
Leaves stomach through pyloric sphincter -goes into small intestine
Chyme
What is chyme
What stomach changes the bolus into, it adds fluids and becomes more liquid food (like gravy)
Rugae is
Folds in stomach wall that expand and contract. Expand to increase volume of stomach
Within gastric pits there are 3 cell varieties found deep in gastric pits in the mucosa layer of stomach they are
1)parietal cells
2) chief cells
3) DNES cells
Parietal cells make what
Make hydrochloric acid (HCL) stomach acid in gastric pits
Chief cells make
Pepsinogen (pro enzyme) and becomes pepsin (enzyme)
DNES cells make (G or endocrine cells)
The hormone gastrin
Small intestine function
Maximize how fast it can absorb molecules into blood or chyme
(Plicae, NOT rugae) permanent folds in wall of small intestine they don’t expand or contract
Circular folds
Finger like projections of mucosa in intestinal wall
Villi
Microvilli
Brush boarder
Large intestine function
Dehydrate the chyme to become feces
Mucosa of large intestine
Simple columnar epithelium , has many goblet cells (mucus makers) to help lay down mucus for material to slide by (to change chyme into feces)
Exit from small intestine into large intestine (still chyme)
Ileocecal valve
Dead ended pouch in digestive system to increase surface area
Cecum
Longitudinal muscle fibers, pulls hard to pull chyme through large intestine
Taeniae coli
Breaking apart of chemical bonds by adding water
Polymer—> monomers
Hydrolysis
Digestive physiology is changing the nature of the food molecules
Polymer (can’t absorb) ——breaks down hydroplane enzymes——-> monomers (can absorb)
3 primary food molecules we eat
1)carbohydrates
2) lipids
3) proteins
Polysaccharides (large complex chains of monosaccharides) need to break these down chemically into single glucose molecules to make it easier to absorb into bloodstream.
Ex: starch, cellulose and glycogen
Carbohydrates
Triglycerides —> glycerol + fatty acids is what molecule (we eat)
Lipids
Polypeptides —> amino acid groups
Proteins
Produces bile, nutrient metabolism, detoxification and excretion.
-releases endocrine/exocrine secretions and converts harmful toxins into non toxic substance body can eliminate
Liver
Sits posteriorly to liver, receives most bile from common hepatic duct. Stores bile, concentrates it (removes water) and releases it when stimulated. Bile release is stimulated by hormone CCK which triggers contraction of smooth muscle in wall of gallbladder causing it to release bile into cystic duct
Gallbladder
Upper left quadrant of abdomen
-endocrine secretion- hormone insulin and glucagon are released from pancreatic islets into blood and affect most cells in body
-exocrine secretion- enzymes secreted primarily by clusters of acinar cells. The enzymes are released into ducts of pancreas that empty into alimentary canal to help with digestion
Pancreas
Pancreas jobs
1) makes enzymes and releases through pancreatic juice and spits into duodenum
2) neutralizes acidic chyme in duodenum by makin bicarbonate ions (HCO3-) shoved in pancreatic ducts and neutralizes acid
Acini cell make what
Enzymes and bicarbonates
Livers jobs
1) make bile salts to emulsify the lipids
2) detoxify blood from digestive organs (happens in sinusoids)
(Liver detoxifies DOESN’T filter)
Liver cells that make bile salts
Hepatocytes
Hepatic portal circulation
-veins come from small intestine, stomach and large intestine and collects all blood coming from digestive organs in abdomen and shoots it in bottom of liver.
-hepatic portal circulation takes all this absorbed blood and send it into the liver before going back to the heart
Purpose of detour of human blood
Arterial and venous blood mix together in little vessels called sinusoids. As blood moves by hepatocytes are able to metabolize out certain chemicals, pull them out of blood, the sinusoids make blood slow down and gurgle. As blood moves toward center of liver lobule hepatocytes pull chemicals out of sinusoids and eventually reaches central vein, then up and out of liver
Chew, ingest food grind into smaller pieces to increase surface area of food
Mastication
Swallowing, specialized type of propulsion that pushed bolus of food from oral cavity through pharynx and esophagus to the stomach
Deglutition
Break down of large fat molecules into smaller ones (happens in small intestine)
Emulsification
Why we make stomach acid
To drive pH inside stomach down low enough so pepsinogen (pro enzyme) becomes pepsin (enzyme)
What breaks bonds between specific amino acids
Pepsin
What is the problem with lipid digestion?
Lipids are snobs
-lipids can’t be efficiently digested until they have been emulsified (this is the job of bile salts from the liver)
Proteins that come from liver to prevent lipids from globing together and allow enzyme to get at the smaller lipids
- can break big lipid glob into little lipid globs
Bile salts
Where all the action happens, bile salts get dumped into duodenum (where they are emulsified) this happens in the
Small intestine
A small lipid droplet surrounded by the bile salts
Micelle
Which organ store bile salts
Gallbladder
Which organ produces bile
Liver
3 phases of stomach secretion
1) cephalic phase -food is on the way, not there yet
2) gastric phase- food enters stomach, more acid released from parietal cells
3) intestinal phase- food left, chyme made it in stomach. Stimulates liver and pancreas and inhibit stomach due to food being gone
Made by endocrine cells in stomach
Increases acid secretion by parietal cells
Gastrin
Made by intestine once food gets there
1) cholecystokinin (CCK)
2) gastric inhibitory peptide
3) secretin
Breaks carbs down into monosaccharides, pump monosaccharides into intestinal cell, they then diffuse out. As soon as it hits blood absorption is done
Absorption of carbohydrates in small intestine
Once protease enzymes have broken down amino acids, pump them into intestinal cells, diffuse out into blood absorption is done
Absorption of amino acids/proteins in small intestine
Micelles take lipids to plasma membrane, lipid diffuse through phospholipid bilayer and enter cytosol. (Bile salts stay out in chyme). Lipids reassemble into triglycerides and packaged into chylomicrons. Chylomicrons are released into the interstitial fluid by exocytosis and then enter the lacteal (absorption is done)
Absorption of lipids in small intestine
Things absorbed in stomach
Water, simple sugar (glucose) and alcohol, protein absorption
Things absorbed in large intestine
Water, electrolytes and vitamins
Describe controls of elimination
(Involuntary reflexes)
1) stretch receptors transmit sensation of rectal dissension to spinal cord.
2) parasympathetic neurons cause smooth muscle in sigmoid colon and rectum to contract and internal anal sphincters to relax
(Voluntary reflex)
3) impulses from cerebral cortex trigger relaxation of the external anal sphincter and contraction of levator ani muscle, allowing feces to pass out of body.
When mass movements force fecal material into the normally empty rectum, it initiates the parasympathetic mediated …
Defecation reflex
Vomiting , normally the stomach moves its contents into the duodenum but emesis is caused when the contents move backwards
Emesis
Inflammation of the liver
Hepatitis
When motility increases, the large intestine doesn’t have time to absorb water from fecal material. This produces a watery feces
Diarrhea
Fibrosis and nodule formation of the liver, liver is scarred and permanently damaged
Cirrhosis
Narrowing of the pylorus sphincter, the opening from the stomach into small intestine
Pyloric stenosis
(PUD) discontinuation in the inner lining of the gastrointestinal GI tract because of gastric acid secretion or pepsin. (Perforation or hole in lining of small intestine, lower esophagus or stomach
Peptic ulcers
Bacterial infection and inflammation of the peritoneum
Peritonitis
Inflammation in you colon, where digested food becomes poop
Colitis
Inflammation of the appendix caused by the appendix becoming blocked mostly by fecal matter.
Appendicitis
Too much stomach acid in pyloric region of stomach
Gastric ulcer
Burning in lining of digestive organ
Intestinal/ duodenal ulcer
Oral cavity function
Ingestion, mastication (chewing) and deglutition (swallowing)
Gastrin function
Increases acid secretion by parietal cells
Histamine function
Increases acid secretion by parietal cells
Serotonin
Distention of the stomach
Stimulates gastric motility
Somatostatin
Decreasing stomach pH
Decreases acid secretion by parietal cells
Partially digested proteins and lipids in chyme entering the duodenum
Causes gallbladder to contract/and release bile; stimulates secretion of pancreatic enzymes from acinar cells; relaxes hepatopancreatic sphincter
Cholecystokinin (CCK)
Chyme entering the small intestine
Inhibits acid secretion from parietal cells
Gastric inhibitory peptide
Intestinal gastrin
Chyme entering the small intestine
Stimulates acid secretion from parietal cells
Motilin
Released regularly during fasting
Stimulates the migrating motor complex of the small intestine
Secretin
Partially digested proteins in the duodenum
Inhibits gastric motility and acid secretion, stimulates bicarbonate ion release from pancreatic duct cells, increases bile production by the liver
Vasoactive intestinal peptide
Partially digested proteins in the duodenum
Inhibits acid secretion by parietal cells; stimulates pancreatic secretion; increases intestinal blood flow
•needed for growth development
•Required for low-light and color vision
• Functions as growth factor for epithelium
Symptoms of deficiency
Delayed growth
• Night blindness and potential total blindness
• Immune dysfunction
Vitamin A (retinol)
• Required for calcium ion homeostasis and bone growth
Symptoms of deficiency
Rickets (in children)
• Osteoporosis
Vitamin D
Antioxidant
Symptoms of deficiency
Anemia
CNS dysfunction
Vitamin E (tocopherol)
Required for synthesis of clotting factors Il, VII, IX, and X
Symptoms of deficiency
Bleeding disorders
Vitamin K
Coenzyme in many catabolic pathways
Symptoms of deficiency
Disease beriberi-peripheral nerve dysfunction, heart disease
Vitamin B1 (thiamine)
Component of
FAD and so critical component of catabolic pathways
Symptoms of deficiency
•Skin disorders
• Dysfunction of other epithelial membranes
Vitamin B2 (riboflavin)
Component of NAD and so critical component of catabolic pathways
Symptoms of deficiency
Disease pellagra-CNS,
gastrointestinal, and skin dysfunction
Vitamin B3 (niacin)
Coenzyme in nucleic acid metabolism
• Required for development of erythrocytes
Symptoms of deficiency
Disease pernicious anemia
Vitamin B12
Antioxidant
• Coenzyme in collagen synthesis
Symptoms of deficiency
Disease scurvy-deterioration of skin and epithelial membranes
Vitamin C
Involuntary contraction and relaxation of longitudinal and circular muscles throughout the digestive tract
Peristalsis
