Exam 4 Flashcards

Question

Secretion

Answer 1

- specific fine tuning mechanism - active process; actively move something from inside the capillary out into filtrate (back into nephron) - blood stream to ISF to ICF of tubule cell to filtrate in lumenal space - result is moving something from peritubular capillaries into the nephron because if we had reabsorbed too much of something or if we didn't filter enough of something we push the excess into the nephron to get rid of it - we have set points for all the different aspects in our blood stream

Answer 2

- filtration: 20% of what is in plasma will all go at same rate and end up in nephron with potential to become urine but we don't want to lose 20% of glucose because we need it for energy - reabsorption: want 100% of load in nephron reabsorbed in PCT; secondary co-active transport with sodium; wants to go down gradient so we allow it to do that by bringing glucose with secretion: not helpful in normal circumstances so normally have 0 glucose in urine

Answer 3

- too much glucose in the bloodstream and 20% reabsorbed - doubling the amount in the blood means we double the amount that needs to be filtered but we have a limited amount of pumps and transporters so they become saturated and only pace it can go is out of the urine - transporters only exist in PCT; glucose draws water toward it as it passes through nephron and prevents reabsorption of water which increases thirst and urination

Answer 4

- found in highest concentration in intracellular fluid - it does repolarization in AP's which will stop if it's not moving how it's supposed to - uses secondary co-active transport - if increased [K+] found in ECF, disruption of AP's and electrical gradients/potentials so communication breaks down

Answer 5

- filtration: 20% of a relatively small quantity because it comes from the ECF - reabsorption: PCT; sodium potassium pump (primary active transport) K+ in nephron moves from outside cells to inside cells very effectively and 100% is reabsorbed - why? very few ions and lots of quick working transporters are able to pull every ion back into the body - secretion: in DCT; K+ reabsorbed too effectively so we have more than we need in bloodstream so eventually peritubular caps secrete excess above set point back into nephron to get rid of it and maintain balance - see no K+ in loop of henle because they come back in DCT

Answer 6

- high concentrations of Na+ and H2O in ECF - need whole nephron because of large quantity - filtration: 20% or each in GC but have very large quantities - reabsorption: PCT almost 99% of each; how: secondary co-active transport pulls sodium across first so water follows-permeability relies on presence of aquaporins-water will only go through if there's osmotic draw and we create this when sodium goes through - 65% reabsorbed in PCT

Answer 7

- establishes vertical concentration gradient: as you go down deeper into the medulla, the concentration rises; established in ascending limb because there are no aquaporins so water is not reabsorbed here so prevents dilution and creates this gradient that we use in the collecting duct - Na+ reabsorption only happens in ascending limb of loop - osmolarity inside this part of the loop will decrease because water is staying and sodium is leaving - urea also helps establish concentration gradient

Answer 8

- regulated, not eliminated - metabolic byproduct - technically waste - osmotically active-draws water toward it to dilute it - 50% filtered urea in nephron pulled back into medulla of kidney and stored in ISF to help make concentration gradient - absorbed by kidney and stays locally in medulla till it's needed - combo of urea and sodium creates gradient (1200 mOsm) - use of urea means we don't use large amounts of sodium because we're using this regulated waste product so Na+ can be sent out to body where it's needed

Answer 9

- only happens in descending loop because it has aquaporins - water leaving has no chance to dilute the ISF because peritubular capillaries bring it in: oncotic pressure gabs water due to the plasma proteins and it gets stuck before it even has a chance to dilute ISF - Na+ not affected here because there are no transport proteins - osmolarity inside the loop will increase because of water loss and sodium retention

Answer 10

- Pcap is 60 mmHG - oncotic pressure of capillary is 25 mmHg: constant - glomerular is only filtering because the Pcap is so high - peritubular: lose large percentage of water which increases osmolarity and decreases total blood volume which means dehydrated blood and a decrease in pressure - the long and dense peritubular network creates friction and resistance so Pcap is decreasing so you switch to net absorption which means oncotic capillary pressure is dominant force to reabsorb water and re-hydrate blood to send out to body

Answer 11

- another 27% of water and sodium reabsorbed in loop and vertical concentration gradient is made - 97% overall reabsorption of water and sodium

Answer 12

- sodium reabsorption adjusted here - final 7-8% - related to aldosterone levels and dietary sodium levels - 7500 g of sodium in body and we filter 1500 g/day which is part of our set point - reabsorption rate is amount reabsorbed/amount filtered (set point sodium and dietary extra) - no matter high sodium vs. low sodium diet rate is still within the last percentage so what we eat is just a tiny drop in the bucket compared to our overall levels - net result is 99% reabsorption in DCT

Answer 13

- water reabsorption adjusted here - final 5-7%; not 7-8% because we need to lose some water to dilute solutes and create urine - related to ADH levels and intake of water - water is not secreted - ADH inserts aquaporins into collecting duct so water is drawn out - net result is reabsorption of 97-99% of water

Answer 14

- secretion of hydrogen ions from capillaries to the nephron - reabsorption of bicarbonite ions - balance between these two keep blood pH at 7.4

Answer 15

- systemic disorders that are misbalaance in pH - metabolic acidosis - metabolic alkalosis

Answer 16

- 7.35 and below - increased acid production in body - systemic cause: stomach tumor increases pH because of increased acid production-proliferation of parietal cells that make this acid which eventually seeps into bloodstream - kidney secretes hydrogen ions into nephron to try to get rid of them and reabsorb more HCO3- ions - kidney failure can also lead to this - also caused by decreased H+ secretion

Answer 17

- 7.45 and above - increased base production: pancreatic cancer-pancreas stores HCO3- ions and if it does this at too rapid of a rate and releases these into ISF blood increases in pH - kidney failure also means too much HCO3- absorption putting it back into bloodstream - increased H+ loss as in excessive vomiting

Answer 18

- help regulate ECF volume by monitoring ISF osmolarity, blood volume, and plasma Na+ concentration within the kidney - ISF osmolarity is monitored by osmoreceptors in hypothalamus so if ISF is more concentrated it draws water from receptors and signals you're thirsty - blood volume regulated by barroreceptors that measure stretch on aortic arch and carotid arteries

Answer 19

- released when blood volume is low and ISF osmolarity is high - stimuli to try to get more water - mechanism: osmoreceptors and barroreceptors stimulate hypothalamus where ADH is made and is then released from posterior pituitary - effect: ADH binds to receptors in CD and inserts aquaporins so water is reabsorbed and captured by peritubular capillaries to dilute ISF and increase BV

Answer 20

- 8% of what was filtered that enters CD (3-4 gallons) all goes through so you pee a lot and are thirsty a lot - ISF osmolarity increases and BP decreases so hypothalamus tells you to drink - treatment: exogenous forms of ADH-ADH receptor agonist; have to use the right amount to maintain number of aquaporins and have to pay attention to intake

Answer 21

- too much ADH produced - very concentrated urine - ISF osmolarity decreases and have too much reabsorption which can lead to hyponatremia (low [NA+]) so AP's don't occur and secondary active transport doesn't occur; can lead to edema and increased BP - treatment: ADH receptor antagonist

Answer 22

- indirectly released when plasma sodium concentration is low-want more Na+ in the blood - juxtaglomerular apparatus: where afferent arteriole contacts DCT and contains macula densa and granular cells - macula densa: sensory cells; part of DCT that touches arterioles (filaments that touch and monitor content) - granular cells: part of endocrine system; primary; surround afferent and some on efferent-secrete substance

Answer 23

- macula densa senses plasma [Na+] - granular cells secrete renin if [Na+] is low (renin is a hormone secreted into the bloodstream so it travels everywhere) - renin converts angiotensinogen into angiotensin I - angiotensin I converts to angiotensin II by angiotensin converting enzyme (ACE) - angiotensin I stimulates secretion of aldosterone from adrenal cortex

Answer 24

- presence of more Na+ transporters in DCT means more reabsorption - 92% of Na+ reabsorbed before DCT - remaining Na+ reabsorbed in DCT to meet body's needs - no aldosterone means another 7% so 99% total reabsorbed - aldosterone present means all 8% remaining is reabsorbed

Answer 25

-filtrate-->minor calyx-->officially urine-->major calyx-->renal pelvis-->ureters-->bladder-->internal sphincter-->external sphincter-->urethra

Answer 26

-use peristalsis to contract to send down urine to bladder

Answer 27

- stores urine - smooth muscle - when stretched enough it opens internal sphincter which signals your brain to tell you you have to pee (involuntary) - then you have control over external sphincter and then you can pee when it's convenient

Answer 28

- distension of bladder with urine - stimulates bladder stretch receptors - sensory input to spinal cord - autonomic motor control: reflex contraction of bladder smooth muscle; relaxation of internal sphincter - voluntary relaxation of external sphincter - urine flows and contents of bladder lost from body

Answer 29

- a way to move air into the lungs-ventilation - a way to keep lungs from collapsing when we exhale-lungs get closer and closer as you exhale because they have little/no structural integrity

Answer 30

- pressure inside lung itself - key issue: lung is passive material that won't change in size or pressure on it's own so we want pressure in lungs to increase when pressure in TC increases - TC muscles control this pressure

Answer 31

- this is what moves air - high pressure to low pressure - so in order to bring air in we have to change pressure relative to atmosphere which is 760 mmHg

Answer 32

-volume of gas is inversely proportional to its pressure

Answer 33

- goal: want air to rush into lungs - needs: lower pressure inside TC (757 mmHg) than outside; 3 mmHg difference needed to bring in 500 ml - mechanics: contract diaphragm to move down and away to increase volume which decreases pressure so gradient is created to allow air to rush in

Answer 34

- goal: move air out of lungs - needs: higher pressure in TC (763 mmHg) than atmosphere - mechanics: relax diaphragm which decreases volume because domes back up into TC which increases pressure to push air out and lungs contract

Answer 35

- breathe faster to get rid of increased levels of CO2 - stimulated to breathe faster to decrease pH - increase in tidal volume during exercise on every breath and faster to keep up with CO2 production - need larger changes in pressure; increase pressure gradient by expanding and contracting TC more than at rest so need extra muscles - exhalation also squeezes more out

Answer 36

- goal: to keep lungs from collapsing - needs: way to keep lungs pinned to TC wall; never able to collapse because TC always has some sort of volume no matter how much it contracts - mechanics: parietal pleura attached to TC wall, visceral pleura surrounding lungs and intrapleural space between the two; thin layer of water in space that creates surface tension to keep the pleura in contact which is what keeps them pinned to ribs so always have some air trapped int lungs because you can't completely exhale all air out due to lungs being stuck

Answer 37

- keeps pleura together - balances out other forces to keep lungs from collapsing - chest wall wants to recoil outward and lungs want to recoil inward so pleura is a "negative" pressure because it has two opposite forces to counter the other two thus canceling them out - want this pressure to be the smallest out of other forces

Answer 38

- surface tension broken and pressure increases to exceed or equal other pressures - lung collapses on injured side - rapid shallow breathing, no deep breaths means no surfactant secreted because type II not stretched this leads to build up of surface tension in uninjured lung which means that it will eventually collapse - not initially affected or directly by the damage because it has it's own pleural system - chest wall on injured side moves outward because it's not being pulled in by pleura - this is called pneumothorax

Answer 39

- how easy it is to expand lung - important because it comes down to effort of breathing and we don't want to use too much energy to breath - as intrapulmonary pressure decreases, how much air enters the lungs? - compliance=change in lung volume/change in thoracic pressure

Answer 40

- normal resting breath is about 500 ml (tidal volume) - pulled in from external and passes through both zones - a fraction of what we're breathing is always stale air because not all air is able to leave the lungs - air comes in and pushes stale air down toward bottom of lungs and exhale but not all leaves - will never be completely rid of CO2 at alveoli end

Answer 41

- graph - normal is exponential rapid rise that eventually plateaus because you fill as much as possible and elastic fibers start to resist

Answer 42

- non-elastic fibers weave through lung tissue - decrease compliance which gives a less steep rise in the graph - lower maximum volume and need a higher change in pressure to get air into lungs - use accessory muscles which uses more energy

Answer 43

- walls between alveoli break down - decreases SA and lose elastic connective tissues which makes gas exchange difficult - less total lung tissue so compliance increases because there are less fibers available to resist - loss of capillaries too means harder to get rid of CO2 - minimal change in pressure to get air in lungs-no issues with inhalation but have change in compliance that's basically useless in their case

Answer 44

- how quickly the lung snaps back to normal/smaller shape after stretch (opposite of compliance) - elastic tension increases during inspiration and decreases during expiration - not a physical force pushing air out-as air moves out it keeps lung in step with air - elastic tension is the stretch of the elastic fibers that eventually makes it difficult to bring in any more air which limits your volume intake - allows lung to maintain typical shape around air

Answer 45

- hydrogen bonds between water molecules because they're polar - alveoli and bronchioles lined by thin layer of water that pull it toward each other and create a collapsing force if allowed to interact in alveoli

Answer 46

- phospholipid detergent that prevents alveolar collapse - secreted by type II alveoli-during deep inhalation - surround water molecules so their nonpolar tails face ourtward which prevents them from touching each other and no H+ bonds are made - limit to how much can be secreted if too much water, not enough surfactant can be secreted and surface tension builds up

Answer 47

- conductive zone warms and humidifies air and pushes pathogens back up - if pathogens reach alveoli they replicate and break up lung tissue and inflammation happens due to WBC draw-->osmotic gradient draws water to alveolus - inflammation slows down gas exchange which can lead to increase surface tension and decrease in compliance - when gas exchange and compliance decrease we have to expand and contract TC more and use auxiliary muscles to breathe faster - increased rate of breathing to try to balance this - if muscle activity increases oxygen demand increases because the muscles are being used more and faster so you breathe faster - can be fatal because eventually you can't keep up with the demands and CO2 levels increase and pH drops, enzymes stop working and you get respiratory arrest and system failure; unable to move gasses across boundaries effectively

Answer 48

- comes from gas molecules "pushing" against a container wall - each gas alone contributes to this

Answer 49

- individual contributions of single gasses to the total pressure - how much this one gas pushes against the container wall

Answer 50

- add up all partial pressures to get total pressure of mixed gas - sea level is 760 mmHg

Answer 51

- 21% oxygen - .04% carbon dioxide - 78% nitrogen - partial pressure will be percentage of each gas x atmospheric pressure

Answer 52

- stale air still in CZ - atmospheric has high [O2] and low [CO2] - these levels change a lot as air is inspired - compositions change because of mixing with the stale air and humidification of new air (add water vapor so takes away from oxygen) but total still has to equal 760 mmHg

Answer 53

- air entering lungs from outside has PO2 of 160 and PCO2 of .3 - air moves through CZ and changes to PO2 of 105 and PCO2 of 40 because of mix with stale air and humidification - blood entering lungs via pulmonary artery has PO2 of 40 and PCO2 of 46 which are the result of internal respiration (gas exchange)-these numbers could change during exercise oxygen would decrease and CO2 would increase because of systemic cell use - next it passes to alveolar capillaries and comes near contact with alveolar air which increases O2 because of the strong gradient (105:40) and this brings oxygen into the blood stream and this also causes CO2 to go into alveolus - from there it travels to pulmonary vein with a PO2 of 100 which relates to hematocrit levels at 100 you've saturated hemoglobin but this number is not maximized because you could go all the way to 105 which is the case with blood doping; PCO2 of 40 which is directly related to PCO2 in alveolus-could be decreased by hyperventilation: allows for more fresh air mixing with same amount of CO2 which decreases amount of CO2 at alveolar level

Answer 54

- no | - TC muscles have not changed so changing volume abilities have not changed

Answer 55

- total pressure decreases which means fewer gas molecules are pushing in air) - in Denver Patm=630 and percentage of O2 is 21 so PO2 is 132 and we expect to see around 160 so we have loss in pressure gradient - still have to go through process of reducing oxygen as it mixes with stale air and we have less oxygen pressure traveling through the body - it's enough because we use 60 at rest and in Denver we start with 70

Answer 56

- deeper you go the higher the pressure will be - for every 10 m you increase pressure by 760 mmHg so double atmospheric pressure - water compresses because of gravity - physical force pushing on rib cage changes ventilation

Answer 57

- at higher pressures gasses dissolve into fluids and you no longer have those bubbles - depressurization means dissolved gas comes out of solution and you see bubbles

Answer 58

- as you go deeper the more pressurized your body is and gasses dissolve into fluid - normally travels through blood stream in tiny bubbles but as pressure increases you increase nitrogen dissolved into your fluids in the body - nitrogen normally has no effect but when it dissolves it affects CNS and acts like you've had a drink; depressive effect - the deeper you go the more it dissolves into blood, ISF, and CSF - increases chances of accidents - deal with it by taking N out of air you breathe and substituting helium because it doesn't dissolve and that pressure has no effect on CNS

Answer 59

- symptoms: skin irritation due to bubbles forming just under skin; headaches and dizziness due to bubbles in neurons; sever joint pain due to bubbles in synovial fluid; paralysis if occurs in motor neurons; seizure if bubbles get to brain - symptoms are usually temporary - problem with going back up to surface too quickly; now gas that's dissolved has to go back to bubble form and you don't want this to happen too fast - supposed to go 5-10 m then wait then go 5-10 more and wait till you get to the surface - large bubbles of gas from going too quickly cause many problems

Answer 60

- H2O + CO2 H2CO3 (carbonic acid H+ + HCO3- - HCO3- binds to RBC's and plasma proteins and you're left with H+ ions so CO2 levels increase and this always acts as an acid in the blood so pH drops - PCO2/pH is the strongest stimulus affecting breathing rate

Answer 61

- normally adjusted to keep pace with metabolic rate - respiratory acidosis - respiratory alkalosis - these to refer to changes above or below the normal breathing rate-not tied into metabolic rate for some reason - these two are quicker ways to maintain pH balance in comparison to kidney's function-kidney only deals with a small portion to make adjustments in H+ and HCO3- which is more helpful in the long term than immediately which is why breathing rate is important

Answer 62

- decreased breathing rate below what we need - hypoventilation: common in concussion or voluntarily holding breath - decrease pH because not getting rid of CO2

Answer 63

-hyperventilation: moving CO2 out of system faster and bringing in more air

Answer 64

- two sets of chemoreceptors detect change in pH and PO2 in blood to modulate respiratory rate - central receptors: medulla oblongata; monitor pH of CSF (mirrors blood pH); have strongest effects on breathing - peripheral receptors: carotid arteries and aortic arch; sense pH and PO2 levels in blood; send feedback to medulla oblongata; slightly less effective

Answer 65

- changes in pH change enzyme function - we make CO2 but we have no control of O2 in the environment-assume it will always be out there but decreases as you increase altitude - this means if we changed BR based on O2 in air it would change all the time but as long as there's enough it doesn't matter - CO2 always matters and we need stability for optimal functioning - BR only changes under extreme circumstances for PO2; arterial PO2 has to fall by 50% before this effect occurs - decrease in PO2 only increases chemoreceptor sensitivity to PCO2 so O2 can decrease but if there's no change in CO2 there is no respiration change

Answer 66

- site of rhythmicity center - lot like SA node - uses inspiratory neurons connected to respiratory muscles and cause contraction and expiratory neurons that inhibit inspiratory neurons and relax muslces and expire air - central pattern generate leads to 12 breaths/minute (baseline)

Answer 67

- modulates activity of rhytmicity center - pneumotaxic center: regulates rate of breathing; increases/decreases frequency that inspiratory/expiratory neurons turn on and off to increase or decrease BR - apneustic center: depth of breathing modulator; deeply breathing keeps inspiratory neurons on longer and delays activity of expiratory neurons

Answer 68

- voluntary control | - frontal lobe can send voluntary commands to respiratory muscles and overrides rhytmicity center

Answer 69

-used to measure lung volumes and capacities and is useful in diagnosing pulmonary diseases

Answer 70

- volume of air entering or leaving lungs during one breath | - usually about 500 ml

Answer 71

- amount of air remaining in lungs after maximum expiration - this happens because you can't collapse the lungs because the job of intrapleural pressure is to keep lungs from collapsing

Answer 72

- the amount of air that can be exhaled after max inspiration - VC=IRV+TV+ERV - passive/resting - maximum expansion of the lungs - limited by size of TC and elasticity

Answer 73

- VE=TV x Respiratory Rate | - amount of air moved into/through entire respiratory system (CZ and RZ) in a minute

Answer 74

- VA=(tidal volume-dead space) x Respiratory Rate - estimate of air that can be used in gas exchange because air in CZ is not useful so this is the amount of air that makes it to respiratory zone

Answer 75

- FEV1/VC - how much there was to begin with compared to how much forced out in one second - similar to ejection fraction - 70-80% is normal - FEV1 is amount of air that can be exhaled rapidly in one second

Answer 76

- largely inward disorders; as you inhale something something resists expansion of lungs - compliance issue - decreased vital capacity - mostly don't see change in FEV1% - ex: pulmonary fibrosis, kiphosis, pregnancy, pneumonia

Answer 77

- difficulty moving air out of lungs due to some sort of blockage - decreased FEV because there's something blocking the air you're trying to force out - ex: asthma, bronchitis (narrowing of CZ and mucus builds up and can block), emphysema (may be easy to move air in but hard to get it out

Answer 78

- smooth muscle surrounding lumen increases and constricts and mucus builds up - increases effort of breathing - affects conducting zone: goal is to make changes here by narrowing it and secreting mucus to keep it from reaching respiratory zone

Answer 79

- allergens-pollen, gluten, etc | - exercise-irritates lining of CZ and see constriction as a protective response

Answer 80

- some people have hyperaggressive immune response to some particles - antigens are recognized as pathogens even though they're not - attacks and prevents inhalation by narrowing pathway and increasing mucus to trap and keep from alveolar level

Answer 81

- sympathetic: bronchodialation and inhibits gland cells that make mucus and this inhibit its production via beta 2 adrenergic (epinephrine/norepinephrine) receptors; (used to inhibit response of asthma); decrease resistance to airflow - parasympathetic: bronchoconstriction and stimulates mucous production via muscrinic (acetylcholine) receptors (excitatory effect)

Answer 82

- binds to receptors and activates them as if it were norepinephrine or epinephrine - stimulates local response: bronchodialation, decrease mucus stimulation - all automatic response so it helps them get rid of their acute response to the stimulus

Answer 83

- motility: movement of food from A-B through organ.system; facilitated by smooth muscle contraction - secretion: digestive enzymes used to break down food and other signals used to communicate with other parts of system - digestion: limit to size of particles we can absorb at a rate that's physiologically useful so we break down to smallest usable parts to move across membranes to increase absorption - absorption: taking in nutrients that have been broken down and pulling them into bloodstream so they can be of use to us

Answer 84

- brain - hypothalamus stimulates hunger - metabolic rate determining how much energy we're seeking - food preference; presence of food makes you hungry - hunger regulation

Answer 85

- stomach - food prep - grinds up food into fine paste to get it into SI

Answer 86

- mostly SI but also LI | - what's useful to us from an absorption standpoint

Answer 87

- chemical secretion where one part of GI tract communicates with another part down the way - starts early in process to get system ready to absorb and digest to minimize waste of nutrients - prepares rest of GI tract for what's going to happen - often starts in cephalic when you smell food to get body ready to hopefully receive the food

Answer 88

- stop signal from last component that travels back to signal previous components to stop - useful for energy conservation; when food leaves one part we don't want that part to continue to use ATP for no reason so we shut it down

Answer 89

- hunger hormone: released when stomach is smallest because it reads stretch receptors - when food does stretch ghrelin decreases - receptors: all throughout body but have lots in hypothalamus; increases levels, more bind to receptors, increased hunger - effects: increased appetite-search for food, affects energy balance-rate of usage of glucose, learning and memory-learn better with increased levels - perception: two meals with same caloric info; one group told high caloric and reported being more full; one group told low caloric and reported still being hungry-can fool body into thinking you've eaten more than you have - ghrelin regulates meal frequency-not amount eaten in any certain meal - feed forward hormone: ghrelin-->brain-->gets us ready to eat

Answer 90

- autonomic control - parasympathetic effects: increased motility, increased secretions to facilitate digestion, more blood to GI for absorption and less to skeletal muscles - sympathetic effects: more blood and oxygen to skeletal muscle and less to GI tract

Answer 91

- Enteric Nervous System (ENS) - automatic behavior within GI tract - has as many neurons as spinal cord so lots of neural communication - mechanism: sensory and motor neurons; sensory are largely stretch receptors linked to smooth muscles to cause contraction or changes in contractions - role: establishes automatic GI motility; peristalsis is controlled by ENS-controlled by how much stretch, not lots of stretch, little activity

Answer 92

- longitudinal muscle: pushing muscle - circular muscle: ringlets surrounding tube-squeezing muscle - neural layers/plexuses between these two-nerve networks - combination of pushing and squeezing muscles accomplish motility

Answer 93

- mechanical breakdown: chewing breaks food into small pieces; not digestion - secretion in mouth: salivary amylase: breaks down carbs, active at neutral pH in mouth; lingual lipase: digests fats, in adults only active at low pH (so not in mouth)

Answer 94

- carbohydrates begin digestion here - proteins and lipids do not - no absorption in mouth - tongue moves food to pharynx

Answer 95

- tube from mouth to stomach and has to pass through diaphragm - amylase active in mouth will be active in esophagus-has same pH as mouth - peristalsis starts: aided by gravity but it's not necessary; contractions behind food and relaxation in front so food moves down tube

Answer 96

- barrier between contents of stomach and esophagus - most circumstances it's tightly closed - only opens when food comes down esophagus

Answer 97

- deep pain right over sternum, vomiting, nausea - caused by something going wrong with LES-breaking down so stomach contents get into esophagus-too acidic - treatments: buffer to neutralize H+ with bicarbonate ions; Prilosec OTC decreases acidity by killing off pumps that pump out H+ so they reduce acid by 99.9%; issues with immune function, less acidity means can't kill pathogens - esophageal cancer is worst case scenario

Answer 98

- most distendable part of GI tract - enclosed by LES and pyloric sphincter which won't open till food is properly prepared - wall has rugae-rough structure that continue mechanical breakdown that started in the mouth - gastric pits have gland cells that have specific roles and secretions-called gastric glands

Answer 99

- Mucous: secreted by mucous cells out into stomach; protects stomach lining, increases [HCO3-] which protects from acid - Pepsinogen: secreted from chief cells; inactive form of pepsin; converted to pepsin at low pH which begins the digestion of proteins

Answer 100

- HCl: secreted from parietal cells; 2 roles-denatures proteins and activates enzymes that actually do the digesting (pepsin doesn't do anything till these are active; cephalic phase is what gears up system to start secretion of HCl) - Gastrin: released with increased stretch in stomach - stimulates parietal cells and chief cells (more pepsinogen and HCl because more food); local communication because it's not talking to any other part of GI tract - Histamine: can come from many different sources-involved in inflammatory process; stimulates parietal cells; increased by spicy foods (because can cause inflammation which releases histamine which binds to receptors and increases HCl secretion which would be bad if you have ulcers)

Answer 101

- no digestion of carbs because salivary amylase is inactive in low pH, have digestion of protein via pepsin, have digestion of lipids via lingual lipase that was secreted in the mouth and is now active at low pH; 10-30% of fat digestion due to lingual lipase pooling in stomach-secrete saliva and swallow which pools and inactive pepsinogen pools so when HCl is secreted there is large amounts of activation; increases efficiency because less stomach has to do at a moments notice-pooling of inactive enzymes between meals so that when you need them you can dump food into active environment - no nutrients absorbed in stomach - do absorb water, aspirin, and alcohol

Answer 102

- storage: holds food until digestion proceeds and intestines are ready to receive it-not motility - mixing: waves of contraction churn food with HCl, lingual lipase, and pepsin - gastric emptying: squirts liquefied food into small intestine a little bit at a time so it can take a while to get a large meal out of stomach

Answer 103

- can happen in esophagus, stomach, or duodenum - symptoms: burning pain not just in location of ulcer, nausea, vomiting, vomiting or pooping blood - causes: most commonly H. pylori; other causes: decrease immune function due to cortisol release in blood too long; lots of aspirin or alcohol - presence of H. pylori doesn't mean ulcers; based on balance of other factors like immune system functioning and amount of bacteria - survive by secreting HCO3- and surrounding themselves and also burrowing into mucous layer - treatments: antibiotics to kill bacteria, bland diet to prevent HCl secretion or protein pump blocker to decrease H+ levels

Answer 104

- plicae circulares: foldings in wall to increase SA - villi: finger-like projections to increase SA - microvilli: projections on villi that increase SA the most, also called the brush border

Answer 105

- aid in digestion - tethered to microvilli so they're not lost with motility of food going through and so they can be used over and over - if not tethered would have to make new via protein synthesis which is a waste of time and energy so we tether them to be used over and over again

Answer 106

- Cholecystokinin (CCK): responds to fats and proteins; stimulates gallbladder; stimulates pancreas (exocrine); inhibits stomach motility (feed-back) - Secretin: responds to H+ in duodenum (acidic food from stomach); stimulates pancreatic release of HCO3- to buffer acids; inhibits parietal cells (feed-back) - Gastric Inhibitory Peptide (GIP): stimulates release of insulin (feed-forward); also inhibits parietal cells (feed-back); linked to type I diabetes (GIP insensitivity means less insulin released)

Answer 107

- produces and secrets bile down common bile duct - role of bile: since fat is nonpolar they congregate into big globs as it interacts with water which decreases SA for lipase to act on - bile emulsifies fat globs into micelles by acting as a detergent and keeping them from reaccumulating - this increases SA for lipases to digest fats - BILE DOES NOT DIGEST FAT-it just increases SA to make digestion more efficient by lipases

Answer 108

- as bile travels down common bile duct, some gets diverted here - this stores and concentrates bile by pulling water out - also ejects bile in response to CCK

Answer 109

- glandular organ near stomach and duodenum - shares common bile duct that liver and gallbladder use - secretions: bicarbonate ions (HCO3-) secreted via stimulus from secretin; changes pH in duodenum to 8 to protect SI; pancreatic amylase: replaces salivary amylase to continue carbohydrate digestion in SI in addition to brush border enzymes; trypsin: replaces pepsin that was degraded to digest proteins; pancreatic lipase: replaces lingual lipase that was denatured continues digestion of fats

Answer 110

- regardless of where it starts, vast majority occurs here - carbohydrates-->monosaccharides - proteins-->amino acids - lipids-->monoglycerides and free fatty acids - carbs and proteins need to be small to fit in transporters to be pulled across - lipids have to be small to facilitate a fast enough rate of diffusion across a membrane-bigger=slow and not useful physiologically

Answer 111

- peristalsis: weak and slow early on-less stretch because thin watery fluid that won't stretch walls to initiate strong contractions-buys us time; picks up as water is absorbed and becomes more solid - segmentation: main contractile activity; involves circular muscles that squeeze down on food-promotes mixing which means more food interacts with more enzyme and more surface area all creating turbulence that allows better chance of efficiently getting enzyme comes in contact with macromolecules to make micromolecules and increases their chance for absorption

Answer 112

- monosaccharides and amino acids absorbed by secondary co-active transport with Na+ - lipids after they cross membrane get put back together with addition of protein and turned into chylomicrons=packaging system useful to cells; so more cells have easy access to use fat, once created they're moved out into lacteal which is an extension of the lymphatic system which sends them to liver for further processing

Answer 113

- caused by decrease in secretion of lactase so lactose can't be degraded into galactose and glucose - symptoms: bloating and gas, abdominal cramps, diarrhea, nausea - bloating and gas: lactose not broken down in SI so it goes to LI where bacteria break it down and release gasses as part of metabolism so the more bacteria active, the more gas is produced=bloating - cramps: gas and bloating increase stretch so receptors sense and we see contraction against this stretch - diarrhea: lactose in LI is osmotically active and pulls water in to try to dilute it - nausea: bacteria become more active and make more byproducts and cramping/bloating and chemical changes make you feel bad

Answer 114

- allergy is an immune response to antigens on milk protein/sugar - have plenty of lactase but your body responds to milk as a pathogen

Answer 115

- continuum of how much lactose you use (evolutionary) - after weaning off breast milk it depends on your need for lactose according to ancestry - did you ancestors have access? If yes you keep expressing lactase, if no why keep it if evolutionarily you weren't exposed, have no use so get rid of it to increase efficiency

Answer 116

- smooth walls with no villi so decreased SA - secretes mucus to lubricate walls and sometimes water is pulled in via osmotic gradient (not common) - a little by remaining enzymes but most by bacteria which grab up anything not already absorbed and use it for themselves

Answer 117

- soluble: partially digested by bacteria: essential for symbiotic relationship-keeps them from eating our cells; they provide up with immune defense and vitamins K and folic acid (B9) - insoluble: remains mostly undigested; osmotically active so draws water toward it so this makes sure there's a balance of water (prevents constipation)-laxatives use this

Answer 118

- no carbs, fats, or proteins (no energy source nutrients) - primarily absorb water and the electrolytes dissolved in water - also absorb vitamins K and folic acid made by bacteria

Answer 119

- peristalsis: move food down length of large intestine because water has been absorbed and there's more stretch - mass movements, churning, and defecation