Digestion Chapter 22

What are the 3 main types of teeth & their ftns?

1 Incisors-cutting off pieces of food 2 canines-(cuspids) ripping and tearing 3 molars & premolars-specialized for grinding rounded projections(cusps)

What are the main fctns of the liver? exocrine-secrete a product thru a duct to outside body amphiphilic:meaning they are both polar/nonpolar parts, Interact with lipids & watery environment. emulsification- bile salts coat lipids & physically break them apart into smaller pieces. liver excretes cholesterol,waste products,toxins(heavy metals) bilirubin-resulting from break down of hemoglobin by the spleen.

1) bile production-bile(liquid)that contains h2o,electrolytes,organic compounds(bile salts derived from cholesterol) 2 ftns: 1) required for he digestion and absorption of lipids 2)bile is the way liver excretes waste & other substances that the kidney can't excrete. 2)storage- stores glycogen 12 hours(overnite) 3)nutrient interconversion- glucose->monomer(carb)->fuel=ATP protein/fat - gluconeogenesis,- formation of new glucose from noncarb precursors, including glucogenic amino acids & glycerol.(happens in liver 90%) 4)detoxification-detoxifies substances produced by body, such as bilirubin. Liver processes alcohol(toxin) metabolizes many drugs such as antibiotics. 5)phagocytosis(cells ingest particles of other cells) - glucose taken in by the liver is stored in form of glycogen & many of dietary amino acids are used to synthesize(synthesis) plasma proteins such as albumin,& clotting proteins.

3 phases of acid secretion pg 864 in book this is a positive feedback loop- once acid concentration reaches ph of about 2.0 then negative feedback is initiated.

3 primary fctns-secretion, propulsion, digestion phase 1-cephalic phase-mediated by sight, smell, taste & thoughts of food. this phase prepares stomach to receive food by increasing the release of hydrogen ions. These stimuli trigger vagus nerve stimulation, resulting in hormone secretion of gastrin, histamine, & somatostatin. 30-40% acid secretion phase 2-gastric phase-begins when food enters stomach(partially digested proteins in gastric juice) & continues stimulation from cephalic phase. Vagus nerve & enteric nervous system(ENS) release ACh which increases acid secretion. These protein fragments stimulate cells to produce & release gastrin, which thru acid secretion activates pepsin which catalyzes protein digestion. Caffeine & alcohol trigger gastrin secretion as well. 50-60% total acid secretion phase 3-intestinal phase-triggered by partially digested proteins in the fluid entering the duodenum which triggers release of intestinal gastrin, stimulating hydrogen ion secretion from parietal cells. As chyme enters the duodenum the declining ph & presence of lipids trigger enterogastric reflex which decreases vagal activity & acid secretion. The low ph also triggers hormone production of secretin & gastric inhibitory peptide(GIP) these reduce acid secretion.

What are the 3 main types of viral hepatitis? hepatitis or inflammation of the liver can be either acute or chronic.

Hepatitis A- mild condition typically spread by bad hygiene(restaurants & child care). Fecal-oral transmission also shellfish from contaminated h20. -Acute -blood borne Hepatitis B- sexually transmitted can cause liver cancer, scarring of liver(cirrosis) -Vaccine -blood borne Hepatitis C- most prevalent form. 4 million cases/yr. 10,000 die. Transmitted via blood, mainly by drug use or sexual transmission. generally body can take care of this. can cause liver cancer, scarring of liver(cirrosis) -chronic disease state -blood borne -no vaccine

Which hepatitis types have a vaccine to prevent it?

Hepatitis B

Which hepatitis types are transmitted thru sharing of body fluids & which one is transmitted by the fecal/oral route?

Hepatitis B & C- spread thru sharing of body fluids Hepatitis A- spread thru fecal/oral route

How is structure related to fctn and surface area in the small intestine?

Internally the small intestine contains 3 progressively 3 smaller types of folds, most absorption takes place here. The folds increase the surface available for absorption about 400-600 times. largest folds-circular folds increase surface area as well as slow down transit of chyme, giving nutrients more time to be digested&more time for enterocytes to absorb nutrients. Villi-projections & intestinal crypts microvilli-found in nplasma membrane(brush border associated with digestive enzymes such as sucrase,maltase,lactase which catalyze reactions that break down peptides) as many as 3000 per enterocyte.

What are the main functions of the gastrointestinal system?

Take food into body & break it down into it's nutrients. *Digestion mechanical- physically breakdown food into smaller pieces via chewing/mixing food. chemical-enzymes secreted by digestive organs, catalyze reactions that break the chemical bonds in food particles until small molecules remain. Ingestion-via mouth, food and H2o taken into digestive system (she says structure & fctn) Mastication-chew ingested food, grinding it into smaller pieces. Aids digestion by increasing overall surface area of the food giving enzymes more surface area to catalyze. Propulsion-passing of ingested food/liquids from one organ to the next. Accomplished by:- peristalsis(rhythmic contractions of smooth muscle of alimentary canal)this is aided by mucus.(secreted by multiple organs) things mixed up Mixing- Secretion-digestive organs contain both endocrine/exocrine glands that secrete substances such as mucus,enzymes,acid & hormones to aid digestive processes. Absorption-once food particles digested, nutrients move thru alimentary canal into blood or lymphatic vessels. Elimination/Defecation-(specialized form of propulsion) ingested materials that are not digestible/usuable by body, exit body thru defecation. Defecation provides body with a way to eliminate metabolic wastes.

What are Micelles?

a small visicle composed of an outer layer of bile salts surrounding inner core of chemically digestd lipids. lipid absorption in gut due to emulsification.

what happens in small intestine?

absorption of nutrients

What are the main parts of the tooth? strongest in body is enamel,next dentin, then bone.

anatomical crown-enamel dentin-under enamel pulp cavity-houses nerves & vessels root canal-nerves & vessels exit here(thru apical foramen) cementum-composed of 1/2 calcium and 1/2 collegen fibers peridontal ligaments-xtends collegen fibers into cementum Alveolar bone- where root of tooth is embedded.

define bolus

chewed, masticated food. mechanical digestion.

What are the main fctns of exocrine pancreas?

enzymes secreted by clusters of acinar cells. enzymes released into the main pancreatic duct that empties into alimentary canal, helping with digestion. Pancreatic juice consists of h20 & multiple digestive enzymes & other proteins. The duct cells secrete bicarbonate ions which makes pancreatic juice alkaline. This helps neutralize the acidic, chyme that enters the duodenum protecting it from damage by acid. Digestive enzymes are crucial in chemical digestion & catalyze reactions that digest carbs,proteins,lipids & nucleic acids. one hormonal mediator of pancreatic secretion is cholecystokinin (CCK) produced in response to presence of lipids & partially digested proteins. Secretin-stimulating hormone released in response to acid&lipids.

Why is diarrhea so potentially deadly?

every cell in body effected by chronic diarrhea. #1 reason of child death - infectious diarrhea. other systems effected: Integumentary,muscular,nervous,endocrine,cardiovascular,Lymphatic&Immune,respiratory,urinary

Where does bile start? pg888 in book

gallbladder. polar/nonpolar, emulsifier. enzyme is chylomicrans.

what is absorbed in the large intestine?

h20, electrolytes,and vitamins are absorbed

Why is the hepatic portal system important? from hypothalamus & pituitary

liver->hepatic portal system->general circulation liver filtration of toxins, goes to hepatic portal vein. This filters toxins after liver.

What is a lacteal?

located in lymphatic capillary in intestinal villi that receives absorbed fats in addition to lymph. lacteals-dump into vena cava, jugular

What are the main ftns of gallbladder? exocrine

mechanical digestion(stores bile,concentrates bile (removing h20) and releases bile(stimulated by the hormone CCK(cholecystokinin)

*test ? Where does digestion start for carbs? What is main enzyme that break down these biomolecules?

mouth(salivary glands)polar travels to bloodstream enzyme is amalase. carbs provide fuel.

What is cause of Celiac disease?

no villi and microvilli in the small intestine.

*test ? Where does digestion start for lipids(fats)? What is main enzyme that break down this biomolecule?

small intestine-nonpolar so much more work to digest. enzyme is lipase

*test ? Where does digestion start for proteins? What is main enzyme that break down this biomolecule?

stomach- directly to bloodstream. enzyme is pepsin-polypeptide down to monomer

What system is in charge of Nervous Regulation of the Digestive System?

the enteric nervous system(ENS). Its a very complex system that takes us to ATP. there are 30 neurotransmitters associated with ENS. 2 major ENS neurotransmitters are acetylcholine & norepinephrine.

What does the gallbladder do and what is it's fctn?

the gallbladder receives most of bile from common hepatic duct. It then stores bile, concentrates it(removes h20) & releases it when stimulated. It is stimulated by CCK. The bile is released into the cystic duct. FCTN: mechanical digestion. It stores, concentrates & releases bile.

What takes place inside the stomach?

the stomachs motility enables it to perform 3 actions: 1) receive food from the esphogus 2)churn the incoming bolus into chyme 3)control the rate at which chyme empties into the small intestine. 1) stomach smooth muscle propels small amount of chyme thru pyloric sphincter, the rest is propelled backwards. 2) the stomachs peristalic waves churn the remaining chyme 3)the remaining chyme is again propelled toward the pyloric sphincter. more chyme is forced thru as the process repeats.