Aulner Digestive Sysem Flashcards by Tayler Schatteman

Functions of digestive system

Ingestion
Mechanical digestion
Chemical digestion
Absorption
Secretion
Defecation/elimination

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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

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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

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Movement of nutrient molecules through digestive wall into blood or lymphatic system is

Absorption

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Adding some product to food as it passes is

Secretion

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Getting rid of material we can’t digest or don’t have time to digest is

Defecation/elimination

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Digestive organs are

Oral cavity
Pharynx
Esophagus
Stomach
Small intestine
Large intestine

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Accessory organs are

Salivary gland
Liver
Pancreas
Gallbladder

Spit on food as it goes by but doesn’t touch the food

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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

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Involuntary contraction and relaxation of longitudinal and circular muscles throughout the digestive tract

Peristalsis

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Sheets of serosa (sheets of peritoneum)

Mesenteries

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Layers that make up digestive tract

Mucosa
Submucosa
Muscularis
Serosa

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Layer touching food with epithelium in it (modified by organ)

Mucosa

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Areolar and dense irregular connective tissue and glands (tiny glands inside epithelium-lymphoid nodule)

MALT= mucosa associated lymphoid tissue

Submucosa

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2 layers of smooth muscle cells (longitudinal and circular layer)

Muscularis

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Mucosa of oral cavity is

Stratified squamous epithelium

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Narrow space between teeth and gums and internal surfaces of teeth and gums is

Vestibule

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Allows us to breath and chew at the same time (mechanical digestion) is

Hard palate

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When swallowing both moves posteriorly to prevent food from entering the nasal cavity

Soft palate and uvula

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Baby teeth”
20- deciduous teeth
4 incisors
2 canines
4 molars in both mandible (bottom) and maxilla (top)

Primary dentin / deciduous teeth

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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

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Wisdom teeth erupt around ages…

17-21

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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

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Made of half calcium hydroxyapatite crystals and half organic compounds like collagen fibers. Hard like bone and cements the teeth in place

Cementum

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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