hbs digestive 3.2.2
what are the functions of the liver?
- converts sugar to glycogen (carbohydrate synthesis) - protein metabolism (process all of amino acids) - lipid metabolism (liver produces and delivers cholesterol = cholesterol synthesis) - releases childhood growth hormone (insulin like factor #1) - breaks down hormones that are not needed (recycled) - breaks down bilirubin (used to make bile) - metabolizes every drug we take
Where do bile and pancreatic enzymes enter the small intestine?
Bile and pancreatic enzymes enter the small intestine through an opening called the sphincter of Oddi in the duodenum located a few inches below the stomach, but only half the bile will enter the duct in the intestine. Bile and pancreatic enzymes are needed for digestion and the absorption of nutrients
What enzymes act inside the small intestine and what are the functions of these enzymes?
ALL INVOLVED IN DUODENUM! Pancreas releases amylase (enzyme that breaks down all carbs "mono" Pancreas releases proteases (enzyme that breaks down protein into amino acids) Pancreas releases lipases (enzyme that breaks down fat into a glycerol to cut up fatty acids) Pancreas releases nucleases (enzyme that breaks down nucleic acids "DNA/RNA") Bile (produced by the liver, stored in the gallbladder) covers the fat particles so enzymes can go in and break them up
What is chyme and how does the stomach mix this material?
Chyme is a thick semi-fluid mass of partially digested food and digestive secretions that is formed in the stomach; it passes from the stomach to the small intestines. The stomach mixes this material by combining food, enzymes, and gastric juices.
How does food move through the intestines?
Chyme moves from the stomach into the small intestine and the muscles mix food with digestive juices from the pancreas, liver, and intestine The muscles push the mixture forward for further digestion. The walls of the small intestine absorb water and digest nutrients into the bloodstream. The waste products of the absorption enters the large intestine. (Waste includes parts of food, fluid, and older cells from the lining of the GI tract) The large intestine absorbs water and changes the waste from liquid into stool. Last, the stool moves into the tectum
What are the three sections of the small intestine and what role does each section play in digestion or absorption?
Duodenum, Jejunum, Ileum
What role does the stomach play in decontaminating the incoming food matter?
The stomach releases enzymes that kill bacteria in food and balances pH. Stomach pH is extremely low
Why doesn't gastric juice digest the inside of the stomach?
The stomach wall is mostly made of protein because if it were left unprotected the acid from the gastric juice would eat through the stomach pores in the stomach (called gastric pits) are holes in the stomach deep in the tissue which leads to a bigger hole and are critical for chemical digestion
What is the function of the tongue?
The tongue helps move food down the throat and helps break down food with chewing and swallowing. It gets the bolus back to the pharynx. It contains taste buds that transmit taste signals to the brain. It also helps with speech.
What mechanical and chemical digestion occurs in the stomach?
a type of mechanical digestion that occurs in the stomach is churning. a type of chemical digestion that occurs in the stomach is the role of gastric acid mechanical digestion- stomach churns to break down food chemical digestion- stomach releases enzymes to break down food ( gastric enzyme, lipase, pepsin, HCL)
Duodenum
first and shortest segment and it receives partially digested food(chyme) from the stomach and plays a vital role in the chemical digestion of the chyme in preparation for absorption; all the enzymes produced by the pancreas are released here; full breakdown of the food breakdown everything into their elements - Protein to amino acids; carbs to monosaccharides; DNA and RNA nucleotides - Ampulla Vater = combination of pancreatic and bile duct; Neutralize the pH level of the chyme from the stomach (lower the number higher the acid) - Brunner's glands (in wall of upper part of duodenum) release mucin (liquid solution) to neutralize pH - Secretin (hormone) tells the pancreas to release hormones to get pH back to neutral - Cholecystokinin (CCK) goes to pancreas and tells the pancreas to release its digestive enzymes (enzymes will not be released until it gets a signal from this hormone)
What is peristaltic movement and how does it function in the esophagus?
peristaltic movement is the constriction and relaxation of muscles in the esophagus and along the entire digestive tract ; it also occurs in stomach and small intestines; it continually forces food through the digestive system in wavelike contractions; smooth involuntary movement
CHIEF CELLS
produces an inactive enzyme called pepsinogen; it forms the active form of the enzyme when it comes in contact with gastric juice pepsin breaks down proteins
Ileum
reabsorb bile salt, B12, provides immune system function for intestines reabsorbs whatever products of digestion were not absorbed by the jejunum
What is the function of the large intestine in relation to digestion?
reabsorption of water and essential vitamins formation and temporary storage of feces maintaining a resident population of over 500 species of bacteria bacterial fermentation of indigestible materials
Jejunum
second part of small intestine; largest section of the small intestine responsible for absorbing nutrients like sugars, fatty acids, and amino acids from digested food into the bloodstream villi - finger like projections hanging down the inside part of the second part of the small intestine outlining villi are absorption cells and goblet cells lumen - opening in intestines absorption cells - enterocytes, absorbing the nutrients goblet cells - produce mucus villi have a capillary bed , nutrients are absorbed into capillary bed and are transported through the bloodstream to the liver Ileum
What are the three sections of the large intestine and what roles does each play in digestion or absorption?
secum - (sack that hangs off the L intestine) houses good bacteria that breaks down food products that can not be broken down with enzymes appendix hangs off secum colon ascending colon - (goes up) major water reabsorption from feces, reabsorbs vitamins and salt transverse colon - (goes across) reabsorb water, salt, and vitamins (same as ascending colon) descending colon- (goes down) stores feces until we can get rid of them sigmoid colon-(s shaped turn into the rectum) storage of feces until we can get rid of them (same as descending colon)
What cells in the stomach function to form enzymes and acids?
simple columnar epithelial cells that make up mucosa; gastric pits (openings that secrete enzymes); The protein digesting enzyme pepsin is activated by exposure to hydrochloric acid inside the stomach.
controls every movement through digestive system
smooth muscle contraction (peristalsis)
D CELLS
somatostatin which tells G cells to inhibits digestion and acid
What is the pH within the small intestine and how is this pH maintained?
The Duodenum has a pH of 6 The Jejunum has a pH of 7-9 TheIleum has a pH of about 7.4
What mechanical and chemical digestion occurs in the oral cavity?
The chemical digestion occurs when saliva mixes with food and breaks down food into simpler foods that can actually be used by the cells. . The mechanical digestion occurs when the teeth break down food through chewing (masticating).
What mechanisms are in place to make sure food does not "go down the wrong tube" and into the windpipe?
The epiglottis is located behind the tongue to seal off the windpipe during eating so the food isn't accidentally ingested into the windpipe and stops it from entering the trachea which prevents choking.
What is a bolus?
A bolus is a small rounded mass of chewed food at the moment of swallowing.
G CELLS
G cells (epithelial) produce a hormone called gastrin that affect parietal cells by telling them to release gastric acid. Parietal cells are the ones that produce gastric acids.
Does any digestion of food occur in the esophagus?
No digestion occurs in the esophagus it just pushes swallowed food into the stomach from the oral cavity esophagus is food tube, trachea is air first layer mucosa is lined with epithelial tissue second layer submucosa is connective tissue with blood supply and nerve tissues outside of submucosa layer smooth muscle layer for contracting outside of smooth muscle layer is serosa connective tissue outermost connective layer adventitia attaches organs for protection
What is the function of the salivary glands?
The function is to produce saliva and start to break down food chemically. The saliva moistens the food to help it go down easier. The parotid gland releases saliva and also, amylase (enzyme) that starts the process of breaking down starch (carbs). Submandibular and sublingual produce the mixture of saliva and mucus. Mucus lubricates and protects, makes bolus slip down esophagus.
What is the oral cavity and what does it contain?
The oral cavity is the first part of the digestive tract. It contains the mouth, teeth, gums, the bony roof, the floor of the mouth, and the cheeks, tongue, salivary glands. This starts the process of digestion by chewing food and adding saliva to begin the swallowing process.
Where are the soft and hard palate located and what are their functions?
The palate is responsible for separating the nasal cavities and oral cavities.They are located at the roof of the mouth. The hard palate is located towards the front (anterior), and the soft palate is in the back part of the mouth (posterior). The soft palate closes off the nasal cavities and the airway during the act of swallowing. The uvula is a part of the soft palate and it is very flexible. This keeps food out of the respiratory tract. The hard palate holds the roots of the teeth and help with chewing. It also helps with some speech.
What are the primary functions of the stomach?
The stomach breaks down food (bolus) after eating and releases nutrients (absorbed in the small intestines), it stores food, sanitizes food with HCL (hydrochloric acid), releases gastric juice to continue chemical digestion, and breaks down protein breaks down mostly proteins and fats garbage compactor (mix it up) takes solid material (bolus) and pulverises it into chyme (acid fluid) sphincter is a one way valve that forces the bolus down, if you have acid reflexes this valve is NOT working (does not close all the way, and acid shoots up into the esophagus.) the fundus is the curvature the body of the stomach is where most of the grinding takes place the pylorus is the junction between the stomach and the small intestine the pyloric sphincter forces chyme into the small intestine the folds in the stomach are called rugae the muscle contractions forces the rugae to grind up food which is the mechanical part
MUCUS PRODUCING
coat in the inner lining of the stomach to protect it from acid
What are sphincters and how are they related to the stomach?
sphincters are the openings in and out of the stomach; they open when allowing food into the stomach or allowing digested food out of it; entrance is called the LOWER ESOPHAGEAL SPHINCTER it regulates food going from esophagus to stomach and keeps contents from reentering the esophagus; the exit is called the PYLORIC SPHINCTER and it governs the food moving from the stomach to the small intestine
