PSIO 202 Exam 4
how do you compare organisms' metabolic rates: - BMR __________ cost of _______ in an ________ . measured on ______ , ________ animals with .... during their ....
Basal Metabolic Rate (BMR) minimum cost of living in an endotherm. Measured on resting, fasted animals with no thermal stress during their rest phase
how to calculate metabolism?
C6H12O6 + 6 O2 -> 6 CO2 + 6 H2O + ENERGY
Pathway of Bile Secretion
- Bile canaliculi join to form bile ducts which form hepatic ducts - L & R hepatic ducts form common hepatic duct - Cystic duct from gallbladder and common hepatic duct join to form common bile duct - Common bile duct & main pancreatic duct empty into duodenum
Composition of Bile - list the values associated with the compositions - bile salts are ____________, meaning that they have ...
- Bile salts: --> Liver Bile: 35 mM --> Gallbladder bile: 310 mM - Lecithin --> Liver bile: 1 mM --> Gallbladder bile: 8 mM - Bile salts are amphipathic (have hydrophilic & hydrophobic domains)
Terms relating to Digestive Health
- Diarrhea: --> chyme passes too quickly through intestine --> not enough H2O is absorbed - Constipation --> decreased intestinal motility --> too much H2O is absorbed --> remedies are fiber, exercise, and water
Blood flow through the liver
In the liver, blood from the hepatic arteries and hepatic portal vein mixes, and the mixed blood flows through the sinusoidal capillaries of the liver before returning to venous circulation
how do you calculate respiratory quotient?
RQ = rate of CO2 produced / rate of O2 consumption
SM have numerous varicosities that release neurotransmitter into _____ in the general area of the SM fiber
SM have numerous varicosities that release neurotransmitter into diffuse junctions in the general area of the SM fiber
alimentary canal?
a continuous tube stretching from the mouth to the anus
4 steps of glucose catabolism
1. Glycolysis 2. Formation of Acetyl Coenzyme A 3. Krebs Cycle 4. Electron Transport Chain (ETC)
Chemiosmosis Summary 1) ___________ are delivered to _____________ 2) Electrons are ________ from __________ to ________ , _________ energy with each __________ that is used to __________ into the __________ between the __________ and ____________ of ____________ 3) H+ ions are ........into the _________ through .... which use .... to ..... of .... from _________ and ________
1. High‐energy electrons are delivered to ETC complexes 2. Electrons are passed from ETC complex to ETC complex, releasing energy with each transfer that is used to pump H+ ions into the space between the inner and outer membranes of mitochondria 3. H+ ions are only permitted to move back into the matrix through special H+ channels which use the energy of H+ diffusion to power synthesis of ATP from ADP and Pi.
digestion of lipids in small intestine 1) what are not digested efficiently by lipase? 2) ___________ raise ______ and act as 3) __________ results from _______ 4) Lipase digests the _____________ into....
1. Large fat globules are not digested efficiently by lipase. 2. Bile salts (produced in liver and gall bladder) raise pH & act as emulsifying agents. 3. Small fat droplets result from emulsification 4. Lipase digests the small fat droplets into glycerol and free fatty acids
which of the following major steps in carbohydrate metabolism requires oxygen? a) electron transport chain b) formation of acetyl coenzyme A c) glycolysis d) Krebs cycle
a) electron transport chain
Gastrin: a) is a hormone released by the G cells of the stomach b) is an enzyme released by parietal cells c) stimulates secretion of pancreatic juice into the stomach d) stimulates pyloric sphincter contraction e) all of the above f) A and D
a) is a hormone released by the G cells of the stomach
digestion in the mouth: describe the 2 types
a) mechanical digestion (mastication or chewing) ---> breaks food into pieces ---> mixes with saliva so that it forms a moist bolus b) chemical digestion ---> enzymatic (enzymes secreted by salivary glands) ---> salivary amylase; begins starch digestion in mouth (pH 6.5-7); when the bolus hits the acidic gastric juices (pH 2.5), digestion stops ---> lingual lipase; begins breakdown of triglycerides (lipids) into fatty acids and glycerol (optimal pH 4.5)
Smooth muscle cells types categorized based on excitation - describe the 2 different smooth muscle cell types
a) single/unitary (visceral) ---> "myogenic" b) multi-unit ----> "neurogenic"
3rd layer of GI tract a) what type of specific tissue? location? what does it control? b) what type of specific tissue? under what type of control? allows __________ for what? c) plexus? part of what NS? receives what type of input? regulates what?
a) skeletal muscle in mouth, pharynx, upper esophagus and anus voluntary control --> control over degultition b) smooth muscle under involuntary control --> inner circular fibers and outer longitudinal fibers --> allows motility for mixing and propulsion c) Myenteric plexus (Auerbach's plexus) --> between inner circular and outer longitudinal muscle --> part of enteric NS --> receives PNS and SNS input --> regulates motility (circular and longitudinal smooth muscle layers)
where in the GI tract is the most water absorbed? a) stomach b) SI c) LI d) rectum
b) SI
which of the following refers to structures present on an individual absorptive cell of the SI? a) lacteals b) microvilli c) plicae circulares d) villi
b) microvilli
both glycogenolysis and gluconeogensis are performed avidly by the liver during a) the absorptive state b) the post absorptive state
b) the post absorptive state
which of the 4 classes of lipoproteins is commonly referred to as "bad" cholesterol? a) chylomicrons b) HDL c) LDL d) VLDL
c) LDL
glucose is absorbed into the epithelial cells of the SI by means of: a) facilitated diffusion b) primary active transport (using a glucose pump) c) secondary active transport (using a sodium symporter) d) simple diffusion
c) secondary active transport (using a sodium symporter)
when the stomach is full, the ileocecal sphincter relaxes so the SI will empty. This is called the... a) gastrocolic reflex b) enterogastric reflex c) iliocolic reflex d) gastroileal reflex
d) gastroileal reflex
which of the following terms refers to the processes involved during the formation of glycogen? a) glycoloysis b) gluconeogensis c) glycogenolysis d) glycogenesis
d) glycogenesis
brush border cells of the SI cannot ingest a) dipeptides b) AA's c) disaccharides d) lipids
lipids
gastric emptying is a) inhibited by distention of the stomach b) inhibited by the release of gastrin c) stimulated by distention of the duodenum d) stimulated by an increase in stomach pH
stimulated by an increase in stomach pH
define metabolism
the chemical processes that occur within a living organism to maintain life
Innervation & stimulation of SM - primarily under control of ... - diffuse branching of .... - transmitters include ... - what is the membrane potential range?
• Primarily under control of ANS-"involuntary" • Diffuse branching of nerve fibers • Transmitters include ACh and NE • Membrane potential ~ -50 to -60mV
Smooth Muscle (SM) - modulates .... - SM tissue is present in .... - located in what organ systems?
• SM modulates luminal pressure/tension • SM tissue is present in sheets, bundles or sheaths around tissues -Cardiovascular system -Respiratory system -Digestive system -Urinary system -Reproductive system
structure of smooth muscle cells - ____________ is poorly developed relative to ___________ - _______ filaments of SM have __________ heads along their _____________ - ___________ and ___________ filaments are arranged diagonally w/in the cell; ________ results in twisting motion
• Sarcoplasmic reticulum is poorly developed relative to skeletal muscle. • Thick filaments of SM have actin-gripping heads along their entire length. • Thick and thin filaments are arranged diagonally within the cell; contraction results in twisting motion.
Regulation of Pancreatic Secretions by Secretin and CCK - secretin - _______ in __________ cause .... which causes....... - CCK - ___________ in __________ cause ... which causes ............
• Secretin- acidity in SI causes secretin release, which causes increased sodium bicarbonate release by pancreas • CCK (cholecystokinin)- fats and proteins in SI cause CCK release, which causes increased digestive enzyme release by pancreas
absorption of electrolytes - list sources of electrolytes? - electrolytes enter ___________ by what processes? --> describe the ions and the process by which they are moved - intestinal ____ absorption requires what?
• Sources of electrolytes --> GI secretions, ingested foods and liquids • Enter epithelial cells by diffusion and secondary active transport --> sodium and potassium move by active transport --> chloride, iodide and nitrate follow passively -->iron, magnesium and phosphate ions use active transport • Intestinal Ca2+absorption requires vitamin D and parathyroid hormone
ATP's Central Role in Metabolism • each cell has about how many ATP molecules? equals ______ of ________ for _______ ; rapid _______ • over _______ of the ..... from _______ is ....
•Each cell has about 1 billion ATP molecules (equals ~2 sec of max contraction for skeletal muscle); rapid ADP-ATP turnover •Over half of the energy released from ATP is lost as heat.
ETC and Chemiosmosis • electrons are _________ in a manner which gets ... • __________ is the final electron __________ - a ..... for the process • the .... of the _______ gradient is used to ....
•Electrons are transferred in a manner which gets as much energy as possible out of them in order to pump as much H+ as possible •Oxygen is the final electron acceptor ---a required step for the process •The potential energy of the H+ gradient is used to make ATP
GI Reflexes
•Enterogastric reflex-regulates the amount of chyme released into the duodenum •Gastroileal reflex-when stomach is full, gastrin hormone relaxes ileocecal sphincter so SI will empty into LI •Gastrocolic reflex -when stomach fills, a strong peristaltic wave moves contents of transverse colon into rectum •Defecation reflex: -when rectum fills, input to sacral spinal cord return commands to expel feces
Overview of Glucose Metabolism
•Glycolysis (break down of glucose) --> glucose to pyruvate/lactate •Glycogenolysis (break down of glycogen) --> glycogen to glucose --> stimulated by glucagon and epinephrine •Glycogenesis (formation of glycogen) --> glucose to glycogen --> stimulated by insulin •Gluconeogenesis (formation of new glucose) --> other substrates to glucose --> stimulated by cortisol and glucagon
Insoluble vs Soluble Fiber?
•Insoluble fiber: - woody parts of plants (wheat bran, vegetable skins) - speeds up transit time & reduces colon cancer - helps with constipation •Soluble fiber: - gel-like consistency -beans, oats, citrus white parts, apples - lowers blood cholesterol by preventing reabsorption of bile salts so liver has to use cholesterol to make more bile - helps with diarrhea
Major Exocrine Secretions of the Pancreas - amount of pancreatic juice that's secreted per day? where is it secreted into? - describe color and pH of pancreatic juice - what does pancreatic juice consist of? - list the enzymes secreted by the pancreas - what are proteases secreted as? list them - what does enteropeptidase activate? - what does trypsin activate?
*- Pancreatic Juice (~1200-1500 mL per day; secreted into lumen of SI)* -> clear colorless liquid -> pH of 7.1 to 8.2 -> consists of: 1. water 2. salts 3. sodium bicarbonate 4. several enzymes *- enzymes secreted by the pancreas* 1. Pancreatic AMYLASE 2. Trypsin 3. Chymotrypsin 4. Carboxypeptidase 5. Elastase 6. Pancreatic LIPASE - *Proteases*: secreted as inactive precursors (similar to pepsinogen in the stomach); trypsin, chymotrypsin, carboxypeptidase, elastase - *Enteropeptidase* (a.k.a. enterokinase; on brush-border cells) activates trypsinogen (converts it to trypsin). - Trypsin activates chymotrypsinogen, procarboxypeptidase& proelastase
Metabolic Functions of the Liver- Carbohydrate metabolism and Lipid metabolism *Carbohydrate Metabolism*: - turn ... into ______ : ________ - turn _______ into ________ : ___________ - turn .... into _________ and store in the _____ : - turn _________ back into ________ as needed : *Lipid Metabolism*: - synthesize _________ - synthesize _________ which are used to transport .... - store ..... : _______ - break down .... : ___________
*Carbohydrate Metabolism*: • Turn amino acids into glucose -gluconeogenesis • Turn triglycerides into glucose -gluconeogenesis • Turn excess glucose into glycogen & store in the liver -glycogenesis • Turn glycogen back into glucose as needed -glycogenolysis *Lipid Metabolism*: • synthesize cholesterol • Synthesize lipoproteins, (e.g. HDL and LDL) which are used to transport fatty acids and cholesterol in the bloodstream • Store some fat -lipogenesis • Break down some fatty acids -beta oxidation
Chemical Digestion in the ________ - where does protein digestion begin? --> what denatures protein molecules? --> __________ activates ______ into _______ --> _________ breaks _______bonds between certain ____________ - _______ digestion continues --> ___________ splits triglycerides in _________ (most effective at what pH?) - what kills microbes in food? - mucous cells secrete _________ to ....
*Chemical Digestion in the stomach* • Protein digestion begins in the stomach - HCl denatures (unfolds) protein molecules - HCl activates pepsinogen into pepsin - pepsin breaks peptide bonds between certain amino acids • Fat digestion continues - gastric lipase splits triglycerides in milk fat, (most effective at pH 5-6 (infant stomach)) • HCl kills microbes in food • Mucous cells secrete mucus to protect the stomach walls from being digested
Compositions and functions of saliva
*Compostion:* - H2O, mucus, HCO3-, enzymes, haptocorrin, lactoferrin, lysozyme... *Functions:* - moistens/lubricates food (swallow) - dissolves food (taste) - HCO3- buffers acidic foods - protects mouth from infection with rinsing action - lysozyme and lactoferrin are antimicrobial
Diseases of the Liver - describe what they are caused by
*Hepatitis*: •Inflammation of the liver that can be caused by a variety of viruses, drugs or alcohol •Can lead to cirrhosis *Cirrhosis*: •Scarred liver caused by chronic inflammation due to hepatitis, chemicals, parasites or alcohol
1st Layer of GI tract a) type of general tissue --- type of specific tissue in .... --- type of specific tissue ... ----- functions of that tissue b) tissue - describe it c) tissue - describe it - drives local _______ to increase ________ by exposing ...
*Mucosa* a) Epithelium -> stratified squamous in mouth, esophagus, and anus -> simple columnar in the rest of the GI tract ---- secretes enzymes ---- absorbs nutrients ---- secretes mucous (via specialized cells (goblet)) ---- secretes hormones (via enteroendocrine cells; control organ function) b) Lamina Propria -> thin layer of loose CT -> contains blood vessels and lymphatic tissue c) Muscularis Mucosae -> thin layer of smooth muscle causes folds to form in mucosal layer -> drives local movements to increase absorption by exposing ingested material to absorptive surfaces
Metabolic Functions of the Liver- Protein Metabolism _________ : • _________ of an ________ from an _________ • _________ skeleton used to ..... • resulting ...... converted into ______ , which is ________ by the _________ ___________: • _________ of an .... • converts ..... into _______ • synthesizes ..... utilized in the __________ mechanism and .....
*Protein Metabolism* Deamination: • removal of an amine group from an AA • carbon skeleton used to make ATP • resulting toxic ammonia (NH3) converted into urea, which is excreted by the kidney Transamination: • transfer of an amine group • converts one amino acid into another • synthesizes plasma proteins utilized in the clotting mechanism and immune system
4th layer of GI tract - describe the tissue
*Serosa or Adventitia* a) serosa for stomach and intestines --> a serous membrane; visceral peritoneum --> secretes serous fluid --> consists of areolar CT covered with simple squamous epithelium b) Adventitia for esophagus --> consists of areolar CT w/out epithelium
2nd Layer of the GI tract - type of tissue? that contains... - what is *beneath* the submucosa ? ---> what NS is it apart of? ---> receives input from _________ and _________ ---> regulates _____________ , ____________ , and _____________
*Submucosa* - loose CT ----> containing blood vessels, glands, and lymphatic tissues - Submucosal plexus (Meissner's plexus): *beneath the submucosa* ----> part of the enteric NS ----> receives input from SNS (thoracic and lumbar spinal cord) and PNS (vagus nerve and sacral spinal cord) ----> regulates blood vessel diameter, secretion from glands, and neurosecretory neurons, and local motility (muscularis mucosae)
stages of swallowing - which ones are voluntary and involuntary? - list the regions associated with each stage
*Voluntary stage:* 1) Oral stage: oral cavity to oropharynx *Involuntary Stages:* 2) Pharyngeal stage: pharynx to esophagus 3) esophageal stage: esophagus to stomach
The Manifold Functions of the Liver - what are the digestive functions?
*• metabolism & storage of carbohydrates, proteins & lipids* • Detoxifies blood by removing or altering drugs & hormones (thyroid & estrogen) • Removes bilirubin (waste product of red blood cell breakdown) *• Releases bile salts to help digestion by emulsification of lipids* • Stores fat-soluble vitamins (A, D3, E, K) • Stores iron, copper and vitamin B12 • Phagocytosis of worn out blood cells and bacteria • Plays a role in vitamin D activation *Digestive functions of liver in bold*
Anatomy of the Small Intestine - total length? - diameter - it has the ________ surface area - most GI __________ and ___________ occurs where? - list the 3 regions of the SI and their corresponding lengths - where does the duodenum start at? - where does the ileum end at?
- 3 m (10 ft) in total length - 2.5 cm (1 in) in diameter - large surface area - most GI digestion and absorption occurs in the SI - 3 sections: a) duodenum = 25 cm (10 in) b) jejenum = 1 m (3 ft) c) ileum = 2 m (6 ft) - duodenum starts at pyloric sphincter - ileum ends at ileocecal sphincter (valve)
Metabolism During Postabsorptive State - _______ hours after a ________ when _________ of all _________ is _______ (similar to ______) - maintaining a .... is a major _________ --> what is the goal?
- 4 hours after a meal when absorption of all nutrients is complete (similar to starvation) -Maintaining normal blood glucose level (70 to 110 mg/dL of blood) is major challenge --> goal is to put glucose back into the blood or use alternative fuel sources
Overview of Lipid Metabolism - lipolysis?: ________ are .... into ....... w/in ..... in the presence of _________ , ___________, ___________ - beta oxidation?: _______ _______ are .... to produce .... - lipogenesis?: __________ are ________ from ________ or __________ w/in ....... in the presence of _________ ; _________ and __________ are __________ from ______________ and _________
- Lipolysis: triglycerides are broken down into glycerol and fatty acids w/in liver or adipose cells in the presence of epinephrine, norepinephrine, cortisol - Beta oxidation: fatty acids are broken down to produce acetyl co-A - Lipogenesis: triglycerides are synthesized from amino acids or glucose w/in liver or adipose cells in the presence of insulin; fatty acids and glycerol are synthesized from acetyl coA and glucose
accessory organs of digestive tract?
- Pancreas - Liver - gallbladder
Stomach anatomy - stomach filling triggers .... - the stomach empties _________ into the ___________ as ___________ of _______ leave through the _____________
- Parts of the stomach --> cardia --> fundus --> body --> pylorus --> pyloric sphincter - Stomach filling triggers secretions and motility - The stomach empties slowly into the duodenum as small squirts of chyme leave through the pyloric sphincter
length-tension relationship for SM - Smooth muscles operate over a ______ range of resting lengths than ____________ - i.e., get _________ length-tension relationship in smooth muscle compared to skeletal muscle
- Smooth muscles operate over a wider range of resting lengths than skeletal muscle - (i.e., get broader length-tension relationship in smooth muscle compared to skeletal muscle)
What are the 4 pancreatic proteases?
- Trypsin - Chymotrypsin - Carboxypeptidase - Elastase
Small Intestine Histology - list the types of cells found in the SI and what they secrete - where are brush border enzymes found? - what do BBEs participate in? - what are the major BBEs of the SI?
- absorptive cell: absorbs nutrients - goblet cells: secrete mucus - enteroendocrine cell: --> S cells make secretin --> CCK cells make cholecystokinin --> K cells release GIP - Paneth cell: secretes lysozyme; is capable of phagocytosis - Brush border enzymes! --> found on surfaces of microvilli --> participate in chemical breakdown of carbohydrates, proteins, & nucleoside - Major brush border enzymes of SI = maltase, sucrase, lactase, aminopeptidase, dipeptidase &enterokinase (aka enteropeptidase)
How is metabolic rate measured? - _________ : measurement of the amount of heat produced by a subject .... - _________ : measurement of the amount of heat produced by a subject ....
- direct calorimetry: measurement of the amount of heat produced by a subject enclosed within a small chamber - indirect calorimetry: measurement of the amount of heat produced by a subject by determination of the amount of oxygen consumed and the amount of carbon dioxide eliminated
Neural and hormonal regulation of gastric emptying: Duodenum - __________ of duodenum and ...... initiate... - these sensory impulses: --> inhibit ... --> stimulate .... --> stimulate .... - cause ________ and _________ release from the ______ --> which also .....
- distention of duodenum and contents of chyme initiate the enterogastric reflex •These sensory impulses: --> inhibit parasympathetic stimulation of the stomach --> stimulate sympathetic impulses to stomach --> stimulate parasympathetic impulses to SI & accessory organs • cause CCK & secretin release from the duodenum.... • (which also decrease gastric activity & emptying)
Neural and hormonal regulation of gastric emptying: stomach - mechanism?: __(action)___ of stomach and ... - __________ and ___________ : --> both stimulate .... --> both stimulate .... --> actions of both are via ...
- distention of stomach & increased pH increase secretion of gastrin & increase parasympathetic activation of the vagus nerve - *the vagus nerve and gastrin:* --> both stimulate the gastric gland (& increase gastric secretions) --> both stimulate contraction of the lower esophageal sphincter and the stomach muscles, as well as relaxation of the pyloric sphincter (& thus increase churning + gastric emptying) --> actions of both are via the enteric NS
Intestinal Phase- controlled release of chyme - entry of _______ into ________ slows _________ and increases________ - Neural influences: distention of _________ and ________ of the __________ activate __________ which .... - endocrine influences: distention of ____________ and ___________ trigger ____________ from .... --> -->
- entry of chyme into duodenum slows gastric activity and increases intestinal activity • Neural influences: distension of duodenum and chemical contents of the chyme activate sympathetic nerves, which slow gastric activity (enterogastric reflex) • Endocrine influences: distension of duodenum and contents of chyme trigger hormonal release from enteroendocrine cells in the duodenum --> secretin decreases stomach secretions --> cholecystokinin (CCK) decreases stomach emptying
what kind of tissue is the digestive system made of?
- epithelium - connective - muscular - nervous
Summary of (aerobic) cellular respiration - in the ______ of _________ , _______ is completely _________ into... - __________ are used by the ________ to pump ________ which are used to make ________ (via__________) - _________________ move out of _______ into the _________
- in the presence of O2, glucose is completely broken down (i.e., oxidized) into: CO2, H2O, and captured high-energy electrons - high energy electrons are used by the ETC to pump H+ ions which are used to make ATP (via chemiosmosis) - CO2, H2O, and ATP move out of mitochondria into the cell's cytoplasm
Major stages of food processing/ main functions of digestive system
- ingestion: eating - digestion : breakdown of macromolecules - absorption: uptake of nutrients by body cells - elimination: passage of undigested and/or unabsorbed materials out of body as feces
Describe the steps in Absorption of Amino Acids and Dipeptides
1. Absorption into epithelial cells of duodenum and jejunum - active transport with Na+ or H+ ions (symporters using secondary active transport) 2. Movement out of epithelial cell into blood - by facilitated diffusion
salivary glands - what are the major extrinsic salivary glands? - salivary gland ________ empty into the ________ - what increases salivation? what NS is associated with increased salivation? - what decreases salivation? NS associated with decreased salivation?
- major extrinsic salivary glands: parotid, submandibular, and sublingual glands - salivary gland ducts empty into the oral cavity - sight, smell, sounds, memory of food, and tongue stimulation increase salivation (PNS) - fear and anxiety (SNS) decrease salivation
Metabolic functions of the liver
- metabolism and storage of carbs, proteins, lipids - removes bilirubin (waste product of red blood cell breakdown) - stores fat soluble vitamins (A, D3, E, K) - stores iron, copper, and vitamin B12
major organs of the digestive system
- mouth - pharynx - esophagus - stomach - small intestine - large intestine - rectum - anus
overview of GI tract functions by location - describe the type of digestion in each location
- mouth: mechanical and chemical breakdown, deglutition (swallowing) - pharynx and esophagus: deglutition, avoiding airway - stomach: mechanical and chemical breakdown; some absorption - small intestine: chemical and mechanical breakdown; absorption of macro and micro nutrients, H2O - large intestine: absorption of electrolytes, H2O, some vitamins - rectum and anus: defecation
peritoneum - peritoneal cavity? - describe the 2 types of peritoneum?
- peritoneal cavity: space containing serous fluid - peritoneum: ---> visceral peritoneum: covers organs ---> parietal peritoneum: lines walls of body cavity
Functions of the Large Intestine - _________ muscle aids in what type of digestion? - describe an action of the LI - _______ waves: how many contractions/min? - what type of churning? - _________ ferment ___________ ___________ into ______ and _______ , and _________ ___________ into ...
- smooth muscle: mechanical digestion - absorption: water, some nutrients - peristaltic waves: 3-12 contractions/min - haustral churning: relaxed pouches are filled from below by muscular contractions; when full, they contract and move contents to next pouch - bacteria ferment undigested carbohydrates into CO2 and methane gas, and undigested proteins into simpler substances
cell types in the stomach - what does each secrete?
- surface mucous cell: secretes mucus - mucous neck cell: secretes mucus - parietal cell: secretes HCl acid and intrinsic factor - chief cell: secretes pepsinogen and gastric lipase - G cell: secretes the hormone gastrin
Unitary SM cells - location? - may not have __________ w/ any _____________ - describe - cell membranes .... - ________ synchronized .... - entire sheet of muscle .......
- walls of the digestive tract, gall bladder, urinary bladder - may not have direct contact w/ any motor neuron - autorhythmic: adjacent cells connect via gap junctions ----> AP transmission from one fiber to another - cell membranes adhere to one another --> transmission of force - slow synchronized "graded" contraction - entire sheet of muscle contracts: "functional syncytium"
how do you make HCl - need to know reaction
- whenever you dissolve CO2 in H2O --> produces acid - source of H2 is coming from blood, source of CO2 is coming from cells - Know how to draw reaction!
the Electron Transport Chain • what is ETC? • what is ETC capable of? • the _____ amounts of .... w/ each _________ is used to make an ..... • the ..... is used to form _______ ; this process is called __________
.• ETC= a series of integral membrane protein complexes in the inner mitochondrial membrane .• ETC is capable of oxidation/reduction (donating/receiving electrons). • The small amounts of energy released w/each transfer is used to make an H+ gradient. • The H+ gradient is used to form ATP; this process is called chemiosmosis
describe the steps in absorption of monosaccharides
1) Absorption into epithelial cells --> glucose & galactose -sodium symporter (secondary active transport) --> fructose -facilitated diffusion 2) Movement out of epithelial cell into bloodstream --> by facilitated diffusion
Recall: 4 major tissues
1) Connective tissue consists of cells that are loosely arranged in a liquid, jellylike, or solid extracellular matrix. 2) Nervous tissue consists of cells with projections that transmit electrical signals 3) Muscle tissue is made up of fibers that contract: a) Striated muscle moves the skeleton b) Cardiac muscle makes up the walls of the heart c) Smooth muscle lines the walls of blood vessels and digestive tract 4) epithelial tissue lines the surfaces of the body
Layers of the GI tract
1) Mucosa (superficial) - epithelium - lamina propria - muscularis mucosae 2) submucosa 3) muscularis - circular muscle - longitudinal muscle 4) serosa - areolar CT - epithelium
what are 3 ways surface area is increased for absorption in the Small intestine?
1) plicae circulares 2) villi 3) microvilli
absorption of lipids 1) ____________ are absorbed by ___________ 2) ____________ and ______________ are sequestered w/in __________ after ____________ by ______ ; will also enter cells by ____________ , leaving ___________ behind ----> _________ are ____________ and later ____________ into ________ by the ___________ ----> ___________ are able to ..... 3) inside __________, ________ are rebuilt and coated with ____________ to form ___________ 4) __________ leave ___________ by ____________ into _________ where they can only ..... ----> travel in ___________ to reach _________ ----> removed from _________ by .....
1. Short-chain fatty acids are absorbed by simple diffusion. 2. Long-chain fatty acids and monoglycerides (products of lipases) are sequestered within tiny *micelles* after emulsification by bile; will also enter cells by simple diffusion, leaving bile salts behind. • Bile salts are also reabsorbed & later recycled (into bile) by the liver. • Fat-soluble vitamins (A, K, D3, E) are able to enter cells w/ lipids. 3. Inside epithelial cells, fats are rebuilt and coated with protein to form chylomicrons 4. Chylomicrons leave intestinal cells by exocytosis into interstitial fluid where they can only enter lacteals (too big for capillaries) - travel in lymphatic system to reach subclavian veins - removed from the blood by the liver and fat tissue
List the phases involved in the Regulation of Digestion
1. cephalic phase 2. gastric phase 3. intestinal phase
beta oxidation of which fuel source produces Acetyl-CoA? a) AA's b) Fatty acids c) ketone bodies d) ribose sugars
Fatty Acids
The Defecation Reflex - ______ reflex: describe - ________ receptors ... - _________ nerves: contract muscles of .... - how is the external anal sphincter controlled?
Gastrocolic reflex: moves feces into rectum •Stretch receptors signal sacral spinal cord •Parasympathetic nerves: -contract muscles of rectum and relax internal anal sphincter •External anal sphincter is voluntarily controlled
which of the following terms refers to the processes involved during formation of triacylglycerol from glycogen? a) glycolysis b) gluconeogenesis c) glycogenolysis d) glycogensis e) lipolysis f) lipogensis
glycolysis -> glycogenolysis -> lipogenesis
Energy transfer • where is energy found? • what is oxidation? • what is reduction? • what is oxidation-reduction?
• *LEO GER* • energy is found in the bonds between atoms • Oxidation is a decrease in the energy content of a molecule: electrons are lost • Reduction is the increase in the energy content of a molecule: electrons gained • Oxidation-reduction reactions are always coupled within the body -- sometimes an intermediate molecule is involved in the electron transfer: coenzyme (NAD+and FADH) or *NADH and FADH2...
absorption of water - how many L of fluid enter the GI tract per day? - what organ absorbs 90% of this water? how many L? - what organ absorbs 90% of the last liter? how many L? - absorption of water is accomplished by what? describe the process
• 6-9L fluid enters the GI tract per day • Small intestine absorbs ~90% of this water (~7-8L) • Large intestine absorbs 90% of the last liter (~1L) • Absorption of water is accomplished by osmosis -through cell membranes into cells and then into the capillaries inside the intestinal villi
Special Features of SM - capable of sustained ___________ w/o fatigue and at ________ energy _____ - maintains a ______ level of tension even in the _______ of APs - stress-relaxation response: ------> stretch causes _______ in tension --> tension _________ w/in __________ --> allows SM to change _________ but maintain ability to _______ (important for _______ organs)
• Capable of sustained contraction without fatigue and at very little energy cost. • Maintains a low level of tension (tone) even in the absence of action potentials. • Stress-relaxation response ----> stretch causes initial increase in tension --> tension decreases w/in 1-2 mins --> allows SM to change length but maintain ability to contract (important for storage organs)
Swallowing: Oral and Pharyngeal Stages • _________ starts with the voluntary stage - _________ pushed by the _______ into the __________ • the ________ stages begin when __________ in the __________ signal the _________ -- list the effects of this
• Deglutition (swallowing) starts with the voluntary stage - food bolus pushed by the tongue into the oropharynx • The involuntary stages begin when sensory nerves in the pharynx signal the deglutition center in brainstem - breathing stops - soft palate & uvula rise closing off nasopharynx - vocal cords adduct - larynx rises - epiglottis covers the larynx
Absorption of Vitamins - list the fat soluble vitamins? - they travel in _______ and are absorbed by ___________ with _________ - how are water soluble vitamins absorbed? - Vitamin _____ must combine with __________ from ________ before it is ________ into the cells of the __________ --- how is this vitamin absorbed?
• Fat-soluble vitamins (A, K, D3, E) - travel in micelles & are absorbed by simple diffusion with lipids • Water-soluble vitamins - absorbed by diffusion • Vitamin B12 must combine with intrinsic factor from the stomach's parietal cells before it is transported into the cells of the ileum - absorbed by receptor mediated endocytosis
mechanical digestion in the stomach - what happens during gentle mixing waves: --> mix _________ with _____________ and turn it into _____________ - more vigorous waves? --> travel from __________ to ____________ ; move _________ along - intense waves? near________ ? --> lead to __________ of the _________ --> release ______ of ___________ into the _________ with each wave
• Gentle mixing waves: mix bolus of food with gastric juice (enzymes, acid, water) and turn it into "chyme" (liquid) • More vigorous waves: travel from the body of stomach to pyloric region; move chyme along • Intense waves (near pylorus): ---> lead to opening of the pyloric sphincter ---> release 1-2 teaspoons of chyme into the duodenum with each wave
Liver's Functional Unit: The Liver Lobule - _________ are the primary cells of the liver, doing __________ - how are they arranged? - spaces between __________ are either ___________ or ________ - ___________ cells ________ microbes and foreign matter
• Hepatocytes are the primary cells of the liver, doing most of the work. • Hepatocytes arranged in grids in lobules • Spaces between hepatocytes are either blood-filled sinusoids or bile canaliculi • kupffer cells phagocytize microbes and foreign matter
Gastro-Esophageal Reflux Disease (GERD) - which sphincter is involved? - what happens if it fails to open and close?
• If lower esophageal sphincter fails to open: - distension of esophagus feels like chest pain or heart attack • If lower esophageal sphincter fails to close: - stomach acids enter esophagus & cause heartburn (GERD) - worsened by a weak sphincter - particularly bad when laying down after a large meal - smoking and alcohol make the sphincter relax (worsening the situation)
Functions of Villi and Microvilli - major function? - what is found on the surfaces of microvilli? - are there brush border lipases? - ___________ w/in ___________ produces __________ that move up to .....
• Increase the surface area for absorption • Brush border enzymes found on the surfaces of microvilli - BBEs participate in chemical breakdown of carbohydrates, proteins, and nucleosides (there are no brush border lipases) • Cell division within intestinal glands produces new cells that move up to replace old cells that have been lost
Transport of lipids by lipoproteins • most lipids are ________ and must .... • lipoproteins are _________ containing .... • lipoproteins are categorized by what? • what are the 4 major classes of lipoproteins
• Most lipids are nonpolar and must be combined with protein to be transported in blood • Lipoproteins are spheres containing hundreds of molecules • Lipoproteins are categorized by function & density • 4 major classes of lipoproteins - chylomicrons - VLDLs (very low density of protein) - LDLs (low density of protein) - HDLs (high density of protein)
Fate of Lipids • ________ to produce ______ • where is the excess stored? • ________ structural or ________ : --> __________ of __________ --> ________ that transport ___________ --> ___________ for _________ --> _________ to speed up _________ --> _________ used to synthesize _____________
• Oxidized to produce ATP • Excess stored in adipose tissue or liver • Synthesize structural or other important molecules --> phospholipids of plasma membranes --> lipoproteins that transport cholesterol --> thromboplastin (phospholipids + tissue factor) for blood clotting --> myelin sheaths to speed up nerve conduction --> cholesterol used to synthesize bile salts and steroid hormones
Cephalic Phase- anticipation - prepares the .... - __(structure)____ - ...... stimulate the ..... to stimulate: ---> --->
• Prepares the mouth and stomach for food • Cerebral cortex - sight, smell, taste & thoughts of food stimulate the parasympathetic nervous system to stimulate: -->Salivation (Facial and Glossopharyngeal) -->Gastric glands to secrete gastric juice (Vagus)
Absorptive State Summary • _________ of excess _______ occurs in .... • most __________ entering _______ is converted to .... • where are dietary lipids stored? • AA's are ____________ to .... or are __________ to _________ or _____________ • AA's are not ....
• Storage of excess fuels occurs in hepatocytes, adipocytes, skeletal muscle • Most glucose entering liver cells is converted to glycogen (10%) or triglycerides (40%) • Dietary lipids are stored in adipose tissue • Amino acids are deaminated to enter Krebs cycle or are converted to glucose or fatty acids • Amino acids not taken up by hepatocytes are used by other cells for synthesis of proteins
Swallowing: Esophageal Stage - what sphincter relaxes during swallowing? - what action occurs? describe it - travel time for solids and liquids? - what sphincter relaxes as food approaches?
• Upper esophageal sphincter relaxes • Peristalsis pushes food down - circular fibers contract behind bolus (to push forward) - longitudinal fibers contract in front of bolus (to shorten the distance of travel) • Travel time - 4 to 8 sec for solids - 1 sec for liquids • Lower esophageal sphincter relaxes as food approaches
Absorption of nutrients by stomach - describe what the stomach absorbs - ________ in the stomach ______ the passage of alcohol to the ________ , where ________ is more _________ - ___________ is _________ more __________ with a meal
• Water • Electrolytes • Some drugs (aspirin, NSAIDs) & alcohol -- Fat content in the stomach slows the passage of alcohol to the intestine, where absorption is more rapid -- Alcohol is absorbed more slowly if taken with a meal
Classes of Lipoproteins • describe the compositions of each • what they form in or what they carry?
• chylomicrons (2% protein, 85% triglyceride): form in intestinal epithelial cells; transport dietary fats to adipose cells • VLDLs (10% protein, 50% triglyceride) --> form in hepatocytes; transport triglycerides to adipose cells • LDLs (25% protein, 50% Chol.): --> bad cholesterol --> carry blood cholesterol to body cells • HDLs (40% protein, 20% Chol.) --> good cholesterol --> carry cholesterol from cells to liver for elimination
postabsorptive state summary • _______ enters blood from the _______ : - what is performed during the postabsorptive state? : - ____________ - _____________ ---> ___________ from __________ ---> _________ and ___________ from ___________ • __________ fuel sources are - _________ from ______________ fed into __________ as __________ - ___________ of ___________ by _________ and ___________ * most __________ switch to utilizing ___________ , except __________ still prefers ____________
• during the postabsorptive state, Glucose enters blood from the liver - glycogenolysis - gluconeogenesis: --->glycerol from adipose tissue ---> amino acids and lactic acid from muscle • Alternative fuel sources are - fatty acids from adipose fed into Krebs as Acetyl CoA for most cells* - oxidation of ketone bodies by heart & kidney *Most body tissues switch to utilizing fatty acids, except brain still prefers glucose.
Lipolysis • ________ undergo __________ in __________ to produce .... • ________ occurs in ________ ; _______ bodies are used by .... for _________ production
• fatty acids undergo *beta oxidation* in mitochondria to produce acetyl CoA and lots of ATP • Ketogenesis occurs in liver cells; ketone bodies are used by heart muscle & kidney cortex for ATP production
Lipogenesis • _________ sources for lipogenesis include: --> ..... for ... from.... --> .... for ....
• fuel sources for lipogenesis include: --> amino acids, glycolysis metabolites, and ketone bodies for fatty acid production from acetyl-CoA --> glycolysis metabolites for glycerol product
Digestion of Proteins: describe the process in each region of the body - mouth? - stomach? - enters _________ from __________ : describe the enzymes - SI: enzymes...; describe what the enzymes split
• mouth -mechanical only • stomach -HCl denatures or unfolds proteins; -pepsin breaks proteins into smaller polypeptides (smaller chains of AA's) • enters SI from pancreas -pancreatic enzymes (proteases) in pancreatic juice; continue to split peptide bonds between AA's • small intestine: brush border enzymes aminopeptidase and dipeptidase: --> split off amino acids at amino end of polypeptides (aminopeptidase) --> split apart chains of two amino acids (dipeptidase)
Digestion of Carbohydrates - describe the process through the organs • ___(organ)___ : enzyme associated with carb digestion • __( organ)____ : type of digestion • enters what organ? from what organ? enzyme? • __(organ)__ : enzymes?
• mouth -salivary amylase(starch to maltose) • stomach -mechanical only • enters SI from pancreas -pancreatic amylase(starch to maltose) • small intestine: brush border enzymes (disaccharides -> monosaccharides) ---- maltase (acts on maltose), sucrase (acts on sucrose) & lactase (acts on lactose) to produce the monosaccharides fructose, glucose & galactose (see diagram!!) - lactose intolerance: those w/out lactase will have bacteria ferment lactose.... the result will be gas and diarrhea.
Digestion of Lipids • organs and enzymes associated with lipid digestion? - organs that it enters? from what organs?
• mouth: lingual lipase • stomach: gastric lipase *gastric lipase function is especially important in infants • enters SI from pancreas: pancreatic lipase in pancreatic juice continues to split triglycerides into FAs and monoglycerides • enters SI from liver: bile emulsifies lipids to form micelles • small intestine -no digestion!* *meaning: no lipase enzymes in the membranes of brush border cells
Fate of Proteins • proteins are broken down into ______ , which are _______ to the _______ • AA's may be: -- _________ to enter ___________ -- .... to form .... (________) -- used to ... • ________ AA's may be converted into .... • absorption of AA's into _________ is stimulated by _______ and _________
• proteins are broken down into amino acids, which are transported to the liver • Amino acids may be: -- deaminated to enter Krebs Cycle -- donate amino group to form new amino acids (transamination) -- used to synthesize new proteins throughout the body • Excess amino acids may be converted into glucose or triglycerides (no storage) • Absorption of amino acids into body cells is stimulated by insulin-like growth factors (IGFs) & insulin
catabolism and anabolism - catabolic reactions ... - anabolic reactions ... - exchange of energy requires use of ________ __________
•Catabolic reactions break down complex organic compounds, providing energy •Anabolic reactions synthesize complex molecules from small molecules, requiring energy • Exchange of energy requires use of ATP (adenosine triphosphate) molecules
Metabolism during Absorptive State • the absorptive state represents ... • the ..... is used for absorption of what? What organ is able to act on these first? • _______ are used for absorption of ________ which are __________ as __________ through the _______ before .....
•The absorptive state represents the time after a meal when nutrients enter the blood and need to be stored •The hepatic portal system is used for absorption of glucose and amino acids. The liver is able to act on these first •Lacteals are used for absorption of dietary fats which are transported as lipoproteins through the lymphatic system before reaching general circulation
