Digestive

*Describe fat digestion by pancreatic lipase is it completed by pancreatic lipase? Describe bicarbonate-rich solution from pancreas including its functions.*

3. Pacreatic Lipase Need bile for this to work Breaks fat into absorbable 1 monoglyceride and 2 fatty acids Pancreas also secretes bicorbonate solution to neutralize acidic chyme

10. *Describe what causes valve release into the duodenum, include cck effect on the gallbladder and sphincter of oddi. Tribe recycling of bile salts why it's important and entro hepatic circulation.*

Between meals bile is shunted in gallbladder to be concentrated During meal gallbladder contracts and empties into duodenum CCK signals this also signals relaxation of sphincter of oddi Fat stimulates CCK After bile is reabsorbed to liver by enterohepatic circulation where its taken by hepatic portal vein Important because not enough bile salts in body every time

*Explain how bile salts help maintain a lipid emulsion. Describe micelles. Explain how bile salts help in absorption of products of fat digestion.*

Bile salts also help fat absorption by forming micells products can dissolve in hydrophobic core Lipase acts of emulsion droplet get monoglycerides and fatty acids which ride in core Transport through water of lumen of small intestine to mucosal lining where they are absorbed

*Define digestion and describe why it's necessary.*

Break down food molecules into small molecules called absorb able units (food is made of repeating units) Then molecules absorbed from the lumen into blood or lymph (if fats)

4.*Explain the functions of chewing. Describe saliva, including its functions and it's important protein. Describe carbohydrate digestion in the mouth what enzyme what are the molecules produced as starches are left in the mouth long enough?*

Chewing reduces size of food and mixes it with saliva to activate taste buds Saliva= mostly water proteins include 1. Mucus- lubricates food 2. enzyme amylase begins the digestion of starches and carbs. From amylose in starch to disaccharide maltose. 3. Lysozyme antibacterial enzyme

1. *Describe the function of the digestive system.*

Digestive System function: To transfer nutrients (water, salts or ions, and vitamins) to the ECF (internal environment)

*Describe the enterogastric reflex. Explain how stimuli in the duodenum act to balance a stomach emptying with ability of the duodenum to deal with it.*

Enterogastric Reflex 1. Stimulus in duodenum 2. activate receptors 3. afferent impulse to CNS 4. Efferent impulse via ANS to stomach to decrease peristalsis and emptying LONG REFLEX

11. *Describe how dejection is completed in the small intestine and the form of food there: in brush border enzymes disaccharidases and describe lactose intolerance, and protein diet enzymes.*

Enzymes on brush border a. Enterokinases change trypsinogen to trypsin b. Disccharidases complete carbohydrate digestion mostly glucose Lactose intolerance- defeciency of lactase cause osmotic gradient and bacteria c. Protein Digestion Enzymes- 2-3 AA are absorb able units

*Explain the factors in the stomach that affect the rate of gastric emptying.*

Factors in stomach affect stomach emptying Increase in fluidity not due to contractions Increase in chyme which causes distention gastric motility and empying causes stretch on muscle stretch receptors involved

*Describe the organs of the digestive system as presented in lecture.*

GI (digestive system) includes organs of long tube and accessory digestive organs. *Organs of tract*- mouth, pharynx, esophagus, stomach, small intestine, large intestine *Accessory Organs*- Salivary glands, liver (makes bile) Gall bladder (stores concentrate bile) Pancreas (Exocrine and endocrine parts; exorcrine secretes enzymes and bicarbonate solution (basic)) Small intestine- duodeum, jejunum, and ileum Large intestine- cecum and appendix, colon (ascending, transverse, descending, sigmoid), rectum

*Define hydrolysis and describe what it does to food molecules. Recognize that digestive enzymes are very specific, and describe how disaccharides are very specific. Know the units of each food category that can be absorbed.*

Hydrolysis=water split

*Explain the factors in the intestine which affect the rate of gastric emptying.*

Increase in distention, fats, hypertonicity, acid in duodenum cause a decrease in stomach emptying

*Describe what the migrating motility comp including its function and the hormone that initiates controls it.*

MMC moves undigested material and bacteria into large intestine controlled by hormone motilin

12. *Describe absorption in the small intestines sodium, camas sugar's, acids as covered in lecture. Identify where most volume is absorbed smaller large?*

Na water active transport sugar, AA, by secondary active transport get a free ride by Na gradient Carbs start in mouth Proteins in stomach Rest in small intestine

7. *Identify what enters the small intestine besides the gastric contents. Describe pancreatic exocrine and endocrine secretions.*

Pancreas and liver also add their secretions Exocrine- Secretes enzymes and a bicorbonate solution Endocrine- Secrets hormones glucagon

*Describe the esophageal phase and the peristalsis that occurs during the esophageal phase. Explain why you can swallow while standing on your head. Describe secondary peristalic waves. Describe heartburn and explain why it occurs in pregnancy. Note that the lower esophageal sphincter is not a true sphincter of strong circular muscle and explain how abdominal pressure normally helps keep the sphincter closed.*

Peristalsis- contraction, pushes bolus into stomach 9 seconds for wave to get to stomach Can swallow while handstand because peristalsis does the pushing If this doesn't get food to stomach secondary peristalsis wave will go as many times as needed Except while swallowing the lower esophageal sphincter closed Heartburn when acidic gastric contents get into esophagus and irritate it. Big meal- inc pressure Pregnancy- big uterus causes increased abdominal pressure forces acid into esophagus Lower esophageal sphincter not a true sphincter no strong muscles abdominal pressure helps keep it closed.

*Describe functions of the pharynx and esophagus.*

Pharynx, esophagus- passageways no digestion occurs, no enzymes

13. *Describe segmentation including how chyme is moved slowly to the part of the small intestine. Describe factors that affect segmentation including the reflex.*

Segmentation mixes chyme and slowly propels it exposes it to mucosa BER also has waves in small intestine higher frequency early than slower in ileum affected by gastric emptying increase segments gastroileal reflex chyme in the stomach causes gastrin release which increases segmentation in ileum extrinsic nerves ANS para inc sym dec

*Explain short reflexes and long reflexes. Explain how a GI in neural reflexes can occur without the CNS involved. Describe how a GI reflexes can be initiated with the smell or sight of food and if emotions can affect GI activity.*

Short reflexes= Without CNS involved From receptor to nerve plexus to effector cells Long reflexes= CNS involved From receptor to CNS to ANS to nerve plexus to effector cells Smell sight and emotions can cause long reflexes too

5. *Describe the regions of the stomach and the pyloric sphincter.*

Stomach is in the abdominal cavity Regions= Fundus, body, and antrum Pyloric Sphincter circular muscle junction between small intestine and stomach Lets out small amount of chyme

*Describe the storage function of the stomach and that it is emptied at a rate for of food. Describe receptive relaxation of the stomach and explain what effect it has.*

Stored in stomach until emptied into duodenum At a rate best for digestion and absorption of food Receptive Relaxation ability for stomach to increase in volume without change in pressure until extreme the smooth muscle does this with control from swallowing center

*Describe the two nerve plexuses that make up the GI tracts local nervous system. Identify whether other organ systems have a local nervous system.*

Submucous and Myenteric Plexus Make up entire enteric nervous system (intestine) No other organ system has this

*Describe swallowing oropharyngeal stage in mouth and pharynx and esophageal stage in esophagus. Explain the events of the oropharyngeal phase of swallowing including those that occurred to keep food out of the respiratory tract. Can you stop the swallowing reflex once it has begun?*

Swallowing voluntarily begins when bolus of food pushed by tongue into pharynx, this stimulates pressure receptors then afferent neurons go to swallowing center in medulla oblongata causing preprogrammed events. Oropharyngeal Phase 1. Soft palate and uvula close off nasal cavity. 2. The trachea is closed off which keeps food from respiratory tract. a. epiglottis acts as lid to cover larynx b. glottis= laryngeal opening closes because vocal cords come together c. Bolus passes the upper esophageal sphincter which then closes takes 1 second cant stop it

9. *Describe bile: Where are synthesized, stored and concentrated, and what it contains. Explain how bile salts assistant fat and why fat digestion would be pull on without bile salts.*

Synthesized in the liver, stored in the gallbladder Contains: bile pigments bilirubin, cholesterol, bile salts which are derivatives of cholesterol, and lecithin a phospholipid Act as a detergent not enzymes to break up things into droplets called emulsification

*Describe why it is that the contents of the GI tract are not considered to be within the body proper or the internal environment. Explain why it is a good thing that the contents of the GI tract are not within the body proper since conditions can be extreme and explain the two examples from lecture.*

The lumen of the tract opens to the outside on both ends, mouth anus. Too harsh examples 1. Stomach pH is 2 very acidic (Stomach ulcer) 2. Bacteria of the large intestine (appendix rupture)

*Explain the effect of the small intestine folds, hey, microvilli on the surface area for absorption. Explain how a paddock portal circulation allows nutrients to go. To the liver after they are reabsorbed. Why? Guy beat portal system identify what doesn't get absorbed into the portal system.*

Villi folds of the inner wall of the small intestine allow for absorption that include microvilli which are projection this increases surface area Nutrients absorbed into capillaries except fats which are absorbed into lacteal of villus these are then taken to liver via hepatic portal vein for processing capillaries to vein back to capillaries capillaries of villi in small intestine to hepatic vein to liver sinusoids

*Describe enterogastrones identify two including their Source in the effect of these hormones on the stomach emptying and secretions.*

enterogastrones hormone that from small intestine which decrease antral contraction and stomach emptying Telling stomach to stop too much Include cholecystokinin and secretin

*Almost all dejection of nutrients and absorption of nutrients occurs in the small intestine. Volume of water is absorbed from the small intestine. Products of fat digestion are recent the size into fat molecules in the cells lining the small intestines and packaged into chylomicrons which enter the lymph.*

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*Because the GI tract has neuron plexus in the tract, reflexes can occur without the central nervous system being involved.*

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*Chewing allows us to swallow food and mixes food with saliva so we can taste the food. Carbohydrate digestion begins with salivary amylase. Swallowing is orchestrated by the swallowing Center in the medulla; there is a pre-programmed, precise complicated, sequence of events that occur during swallowing.*

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*Digestion breaks large food molecules into smaller molecules that can be absorbed. The digestive system consists of organs of the digestive tract and accessory organs that secretes substances into the tract*

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*Secretin and chyloecytokinin are hormones from the small intestine which stimulate different types of secretions from the pancreas.*

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*Segmentation is a mixing movement that occurs in the small intestines segmentation also moves chyme slowly towards the large intestine. Migrating motility comp after absorption of nutrients and move the contents of the small intestines into the large intestine*

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*The absorbable units of the main food categories are: For carbohydrates monosaccharides, for protein amino acids or di or tripeptides, and for feds monoglycerides and fatty acids.*

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*The digestion and absorption of fats is different than other food molecules because fats are not water-soluble. Bile salts are very important in maintaining small fat droplets in the watery chyme maintaining an emultion which helps with fat and informing micelles which helps absorption of fat products.*

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*The pancreas and the liver release their secretions into the small intestine which are mixed with chyme from the stomach. Go hydrate. Was halted in the stomach with salivary amylase HCL. The pancreas secretes enzymes for carbohydrates, fat, protein digestion. Protein digesting enzymes are secreted in inactive forms. Pancreatic enzymes work best in an alkaline environment; the pancreas secretes an alkaline bicarbonate solution into the duodenum.*

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*The same hormone that causes the pancreas to secrete enzymes also causes contraction of the gallbladder. Bile salts are absorbed and returned to the liver to be secreted again.*

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*The stomach secretes a protein testing enzyme in an inactive form, hCL, mucus as does the whole GI tract lining, and gastrin a hormone.*

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*Water is absorbed from the large intestine. Bacteria in the large intestine produce vitamins and gas. Haustral contractions mix the context of the large intestine; mass Movement contents to the rectum*

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*Identify the gastric secretions and describe their functions there are several for HCL. Identify the cell types that secrete pepsinogen / HCL. Explain why pepsin is secreted in an inactive form what kind of enzyme is it? And how pepsin is activated. Define autocatalytic and apply it to pepsin.*

1. HCL Secreted by parietal cells Functions a. Kill microbs b. uncoils protein H+, by affecting connective tissue. c. activates pepsinogen d. creates acid environment for pepsin 2. Pepsionogen Secreted by Chief Cells protein that starts digestion Inactive form called pepsinogen which protects secreting cells from digestion Pepsin acts on pepsionogen its autocalytic

*Describe the state of carbohydrate digestion once chyme gets to the duodenum. Explain what an activate salivary amylase. Describe the state of carbohydrate digestion after pancreatic amylase Acts. Describe activation of pancreatic protein Digest enzymes. Explain how trypsin is autocatalytic. List of pancreatic protein digesting enzyme explain how their digestive activity is different. Is protein Digest finished or are there more enzymes that act on proteins?*

1. Pancreatic Amylase- Starch digestion began with salivary amylase and continued working until HCL inactivated it Still not done with carb digestion not monosaccarides yet. 2. Protein digesting enzymes Secretes inactive trypsinogen Enterokinase which is on duodenum then splits a peptide off trypsionogen=trypsin which then activates inactive enzymes autocalytic because it activates itself Trypsinogen=Trypsin=Inside Chymotrypsinogen=Chymotrypsin=Inside Procarboxypeptidase=Carboxpeptidase=outside Still not done with protien digestion more enzymes

3. *Describe the four layers of the GI tract as presented in lecture.*

1. Serosa- outer layer, secretes fluid. Aka visceral peritoneum. 2. Muscle layer- smooth muscle. Outer longitudinal layer and and inner circular layer (constricts). 3. Submucosa- Connective tissue with nerve cells, blood and lymph vessels and glands. 4. Mucosa- innermost layer of mucous membrane= membrane that secrets mucus that lines the entire tract.

*Describe the function of mucus secreted what is the effect of the alkaline mucus? Describe the function of intrinsic factor which is secreted by which cells? Explain why intrinsic factor is called the only absolutely essential substance from the stomach. Explain why a lack of intrinsic factors cause anemia.*

3.Mucus Secreted in entire GI tract Alkaline protective coating, pepsin needs acid to work and mucus is pH7 so it cant work on mucosal cells. 4. Intrinsic Factor Secreted by parietal cells for B12 absorption. B12 needed for DNA synthesis and hemoglobin and rbcs causes pernicious anemia pepsin is not essential because small intestine can digest proteins without it

*Describe what region of the stomach secretes gastrin and what effect gastrin has on cells in the body of the stomach. Can I use that gastrin is a hormone secreted into the blood to have its effects. List the other controls of hCL secretion besides gastrin. Define differences in glands in the stomach-glands in the antrum compared to glands in the body. Describe gastrins effect on Chief cells.*

5. Gastrin Goes into blood not stomach Secreted by antrum cells in pyloric area also stimulates acid secretion by parietal cells and chief cells to secrete pepsionogen Antrum glands secrete gastrin and body secretes HCL

2. *Explain how the three main categories of foods are digested.*

Carbs-monosaccarides (glucose, galactose, fructose) Proteins- amino acids Fats- 1 monoglyceride and 2 fatty acids also absorbtion of 2-3 aa linked

*Describe absorption of products of fat digestion by diffusion and then what happens? You should explain the entire figure including what is produced inside the intestinal cell? What's a chylomicron and what's the reason it is synthesized? A mistake Island Micron enter the lacteal capillary instead of the blood capillary? Describe absorption of vitamins as presented in lecture*

Fat absorbed into lymph, lipase hydrolzes fats into fatty acids and monoglycerides, carried by micells because water soluble to luminal mucoasal surface of small intestine via diffusion into membrane because lipid soluble then they are re synthesized into triglycerides packages and coated with lipoprotein making them chylomicrons which are then exocytosis then enter lacteal vessel of villus ADEK Vitamins that are fat soluble carried by micelles with fat products and water soluble are diffused to enter mucosal cells except B12 tthat needs intrinsic factor and is absorbed by endocytosis in terminal illium

*Describe the stomachs basic electrical rhythm. Describe how nerves and hormones affect the strength of antral contractions and affect gastric emptying.*

Fundus has pacemaker cells cause slow waves Creates Basic Electrical Rhythm BER 3/min Nerves and hormones can cause depolarization further and get more contraction or hyperporalize and prevent them Amount of chyme that gets into duodenum depends on these antral contractions

14. *Know the functions of the large intestine do they secrete enzymes? Bacterial Flora in the large intestine and their effects include vitamin and gas production. Describe the source and importance of vitamin K. Explain why a deficiency in vitamin K and infants can occur. Describe hostile contractions and mass movements. I'm the two anal sphincters the defecation reflex and how the reflex can be delayed.*

No enzymes secreted mucus secreted Function to absorb water and electrolytes and store fecal and bilirubin Bacteria make vit K which is needed for blood clotting break down stuff we cant and get gas Haustral Contractions mix movement like segmentation but less frequent produce sacs also exposes to absorptive mucosa Mass movement like gastroileal reflex gastrin increases colon activity large portion of colon contracts distention of rectum stimulates stretch receptors to cause defecation reflex 2 sphincters 1. internal anal sphincter smooth muscle 2. External sphincter skeletal muscle can control Most alcohol absorbed in small intestine fatty meal slows down stomach emptying

6. *Describe gastric emptying and motility include the peristalic waves in the other areas of the stomach compared to the antrum. Define chyme. Describe how chyme is propelled through the pyloric sphincter and how mixing occurs in the stomach.*

Peristalic waves are stronger at the antrum because thicker muscle Waves mix contents and close pyloric sphincter Before closure chyme moves into duodenum Most of it forced backwards because hits the sphincter and mixes more Chyme= Sludge in stomach= partially digested food and enzymes

8. *Describe regulation of pancreatic secretion. Explain what causes secretin / cck to be released and the effect of each hormone on pancreatic secretions. What's special about secretin?*

Secretin released in response to acid in duodenum Cause pancreas to increase bicorbonate solution First hormone discovered CCK release in response to fat and proteins in duodenum Cause pancreas to release more enzymes for digestion