Term
Factors causing Vasoconstriction and dilation (4)
chemical and physical |
|
Definition
Chem
1: local metab changes (O2, CO2, acidity)
endothelin --> constriction
NO2 --> dilation
2: histamine release
Physical (ex. exercise)
3: local application of heat or cold
4: myogenic response to stretch |
|
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Term
SNS extrinsic control
Inc SNS =
Dec SNS = |
|
Definition
releases norep onto alpha-adrenergic receptors
vasoconstriction
vasodilation |
|
|
Term
Hormonal influence on arterial diameter
ep and norep |
|
Definition
Adrenal medulla --> ep and norep
ep --> beta-2 = dilation
norep --> alpha-1 = constriction |
|
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Term
Hormonal influence on arteriolar diameter
vasopressin (ADH) and Angiotensin II |
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Definition
both potent vasoconstrictors
released when SNS activity is high in order to vasoconstrict
ADH = H20 balance
Angiotensin II = plasma volume/Na+ balance |
|
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Term
Capillaries
method of transport?
thickness?
velocity? |
|
Definition
| DIFFUSION! -diffusion distance minimized -thickness of diffusion barrier minimized -tremendous surface area available for diffusion -blood velocity slows through capillary beds |
|
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Term
|
Definition
-inbetween flattened endothelial cells, allows for movement of small H20 soluble substances b/w capillaries and interstitial space (glucose, Na+, K+, AA, NOT proteins or RBCs)
-lipid soluble substances pass through endothelial cells (O2, CO2)
-exchangeable proteins are moved across by vesicular transport |
|
|
Term
1.Metarterioles
2.Precapillary Sphincters |
|
Definition
1. Allows for faster transport thru the capillaries, but less opportunity for diffusion (less exchange). When tissues have less metabolic needs, blood uses metarteriole route.
2. bands of smooth muscle at gates of metarterioles controlled locally. When constricted, blood flows thru metarterioles. |
|
|
Term
|
Definition
-to regulate the distribution of ECF b/w plasma and interstitial fluid
-completely passive process
-direction of bulk flow movement determined by capillary blood pressure |
|
|
Term
1. Ultrafiltration
2. Reabsorption |
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Definition
1. intravascular space --> interstitial space. A + net exchange results in Ultrafiltration.
2. interstitial space --> intravascular space. A - net pressure results in reabsorption |
|
|
Term
|
Definition
pushing P
1. Interstitial HP = unchanging, promotes reabsorption
2. Capillary blood P = can change, promotes ultrafiltration |
|
|
Term
Oncotoic (colloid) P =
1. Plasma oncotic P
2. Interstitial oncotic P |
|
Definition
pulling pressure
1. pulling P from w/in the capillary by means of plasma proteins (albumin), promotes reabsorption.
2. promotes ultrafiltration |
|
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Term
|
Definition
excess fluid picked up, now called lymph
too much ultrafiltration or not enough reabsorption = edema |
|
|
Term
| Factors that influence venous return (5) |
|
Definition
1. sympathetically induced venous constriction (dec compliance)
2. skeletal muscle activity
3. effects of venous valves
4. respiratory activity
5. cardiac suction: ventricles contract, atrial V inc = negative P --> VR |
|
|
Term
|
Definition
-"blood reservoir," 60% total BV in systemic veins b/c they are very compliant (capacitance vessels)
-inc cap, dec VR |
|
|
Term
| Orthostatic hypotension/syncope |
|
Definition
| blood pools in legs --> dev VR --> dec CO --> dec MAP --> syncope |
|
|
Term
|
Definition
main driving force in supplying blood to the tissue
-inc workload on heart
-inadequate perfusion |
|
|
Term
| Control of MAP 1. Short term regulation |
|
Definition
concerned w/ moment to moment BP Baroreceptor reflex:
Involves carotid and aortic arch baroreceptor
BP too high --> CV center in medulla --> inc activity in vagus nerve (parasympathetic) --> dec HR --> dec CO --> dec MAP |
|
|
Term
Control of MAP
2. Long-term regulation |
|
Definition
renal influences in plasma V (sensed by JGA granular cell baroreceptors)
1. Thirst mech
2. Urine output
3. Salt balance |
|
|
Term
|
Definition
1. filtering organs
2. endocrine organs (produce erythropoetin)
3. metabolic organs (gluconeogenesis) |
|
|
Term
| nephron:collecting duct ratio |
|
Definition
|
|
Term
1. afferent arteriole
2. glomerulus
3. efferent arterioles
4. peritubular capillaries
5. bowman's capsule
6. JGA |
|
Definition
1. leaves artery, delivers blood to glomerulus
2. tuft of capillaries
3. branches into peritubular capillaries
4. engulf and surround nephron, some movement of fluid and substances b/w peritubular capillaries and part of the tubule
5. surrounds glomerular capillaries, where fluid first moves into from capillary space
6. adjacent to glomerulus, specialized cells that secrete vasoactive mediators, allows tubular cells to monitor the rate of fluid flow |
|
|
Term
Regional differences in nephron (2)
1. Superficial cortical nephrons
2. Juxtamedullary nephrons
- vasa recta
Differ anatomically (3)
Functional (1) |
|
Definition
1. nephrons more superficial, short loops that do not plunge very deep (80%)
2. nephrons more near the medulla, long loops that span the entire length (20%)
- vascular component, wraps around nephron as a network of capillaries
1. nephron location
2. henle length
3. vascular component
Functionally, JG nephrons critical in altering [] of urine (choose how much h2o eliminating) |
|
|
Term
3 basic renal processes
1. Glomerular filtration
2. tubular reabsorption
3. tubular secretion |
|
Definition
1. 20% of plasma is filtered and enters bowman's capsule, no energy requirements, non-selective
2. move from RT --> peritubular capillaries, conserving for the body
3. move from PT capillaries --> RT, eliminate from the body
2 + 3 passive OR active, ALWAYS selective |
|
|
Term
Renal Corpuscle =
Glomerular mb (3 layers)
1. Wall of glomerular capillaries
2. basement mb
3. inner layer (w/ podocytes) |
|
Definition
glomerulus + bowman's capsule
1. inner-most layer, composed of 100x leakier endothelial cells
2. acellular layer of connective tissue, mostly glycoproteins, abundance of (-) glycoproteins, prevents movement of these thru glomerular mb (keeps them in capillary space)
3. foot processes that interdigitate, create another filtering layer, good at retaining proteins + allowing for movement of everything else |
|
|
Term
Forces involved in Glomerular filtration
1. Capillary blood P
2. plamsa colloid osmotic P
3. bowman's capsule hydrostatic P |
|
Definition
1. pushing, driving force for glomerular filtration (55 mm Hg)
2. pulling, opposes filtration (30 mm Hg)
3. pushing, oppose filtration (15 mm Hg)
55-30-15 = 10 mm Hg Net Filtration P
*DOES NOT involve oncotic P b/c there is no protein |
|
|
Term
| Rate of Glomerular filtration |
|
Definition
GFR = Kf x net filtration P
Kf = filtration coefficient (SA and
permeability)
net filtration P = +10 in healthy individual |
|
|
Term
|
Definition
1. Autoregulation (goal = maintain GFR in the face of normal fluctuations in BP)
2. Extrinsic sympathetic control (goal = alter GFR in an attempt to control BV and BP) |
|
|
Term
| GFR Autoregulation - The Tubuloglomerular feedback mech |
|
Definition
changes in BP result in changes in the rate of fluid flow through the distal tubule - sensed by macula densa cells
-macula densa cells stimulate granulosa cells to release a vasoactive mediator to act on the afferent arteriole
-BP rises, causes temp rise in GFR and inc rate of fluid flow thru distal tubule, macular densa cells stim granulosa cells to release a vasoconstrictor - brings GFR back down + vice versa |
|
|
Term
| Arteriole Diameter and GFR autoregulation |
|
Definition
| -kidneys maintain steady glomerular blood flow and a stable GFR by altering diamter of efferent arteriole (vasoconstriction + dilation) |
|
|
Term
| Extrinsic (Sympathetic) control of GFR |
|
Definition
-sympathetic input can override autoregulatory responses
-smooth muscle cells of afferent and efferent arterioles contain many alpha adrenergic receptors
-renal nerve releases norep --> constricts arterioles |
|
|
Term
Tubular reabsorption
what gets absorbed? |
|
Definition
99% of H20 filtered is reabsorbed
100% sugar filtered is reabsorbed
99.5% salt filtered is reabsorbed |
|
|
Term
|
Definition
ACTIVE
-80% of energy requirements of the kidneys used for Na+ transport
-99.5% Na+ filtered is reabsorbed |
|
|
Term
Na+ reabsorptoin
1. proximal tubule |
|
Definition
| 1. plays role in reabsorption of glucose, AA, water and urea (Na+ transport coupled w/ these, cotransport) |
|
|
Term
TM (tubular maximum)
renal threshold |
|
Definition
of glucose = 375 mg/min is a RATE
-whenever transport depends on a
cotransporter, the rate can be
saturated --> there is some max of
transport
max plasma [] any of the organic nutrients can reach before it starts to appear in the urine
ex. glucose = 300 mg/ml |
|
|
Term
Na+ reabsorption
2. in the ascending loop
3. distal tubule
4. collecting duct |
|
Definition
2. Na+/K+/2Cl- cotransport on luminal side
3. Na+/Cl- contransport on luminal side
4. Na+ channel on luminal mb |
|
|
Term
| Na+ reabsorption is coupled to passive Cl - and water reabsorption + is hormonally regulated |
|
Definition
-ALWAYS PASSIVE, via osmosis (osmotic gradient created by movement of Na+)
-80% is reabsorbed in the proximal tubule and the loop of henle |
|
|
Term
2 mechanisms for water reabsorption
1. Paracellular route
2. Transcellular route |
|
Definition
1. inbetween epithelial cells, controlled by leaky tight junctions which can vary in leakiness
2. thru the epithelial cells via aquaporins on the luminal mb
- availability of aquaporins is dependent on [] ADH |
|
|
Term
Na+ reabsorption coupled to passive Cl- reabsorption
1.
2. |
|
Definition
1. Cl- is reabsorbed creating an electrical gradient
2. Na+ and water reabsorbed leaving high [] of remaining substances in lumen --> Cl- and urea travel down [] gradient and is reabsorbed
2. |
|
|
Term
| Regulated reabsorption of PO4-3 and Ca+2 |
|
Definition
-reabsorption of some substances helps regulate plasma [] of those substances
-renal threshold = normal plasma levels
-renal threshold for phosphate reabsorption set at normal plasma phosphate [] --> excess is excreted in urine
ex. want Ca+2 levels = 10, set renal threshold = 8-10 |
|
|
Term
| What does not get reabsorbed? |
|
Definition
-waste products except for urea (can be used to form new proteins)
-phenols and creatinine do not
-tubule is impermeable to these products |
|
|
Term
Summary of Reabsorption
1. Prox tubule
2. Loop
3. Distal
4. Collecting duct |
|
Definition
1. 65% of filtered Na+ and Cl-, 80% of H20 reabsorbed
2. 25% of filtered Na+ and Cl-, 15% of H20 reabsorbed
3. Na+ and Cl- variable, very little H20
4. Na+ and Cl- variable, H20 variable |
|
|
Term
Tubular secretion
substances? |
|
Definition
-selective movement of substances from peritubular capillaries --> tubular lumen
-H+ ions, K+ ions, pollutants, drug metabolites (organic anions + cations) |
|
|
Term
H+ ion secretion
role?
where does it occur + by what mech? |
|
Definition
-plays important role in acid/base balance in body
1. proximal tubule - Na+/H+ antiporter
2. collecting duct + loop - facilitated diffusion |
|
|
Term
K+ secretion/absorption
where, what mech for secretion + absorption
secretion/reabsorption regulation?
aldosterone? |
|
Definition
-undergoes BOTH reabsorption and secretion
-reabsorbed in proximal tubule via passive diffusion
-actively secreted in distal tubule and collecting duct
-reabsorpion = unregulated
-secretion = regulated
- low [K+] --> secretion is minimal
- high [K+] --> secretion enhanced
-ADH opens luminal Na+ channels and increases Na+/K+ ATPase expression |
|
|
Term
| Why isn't K+ secreted throughout the tubule when Na+ is reabsorbed? |
|
Definition
-K+ channels confined to BL mb in proximal tubule + loop, so K+ cannot enter the tubular lumen
-in distal tubule and collecting duct, K+ channels on luminal mb, so K+ is allowed to enter tubular lumen |
|
|
Term
Organic anion and cation secretion
where?
what do they involve? |
|
Definition
-organic anion pathway and organic cation pathway
-is a secretory pathway bc --> (1)some of the ions can be bound to plasma proteins and are never filtered by glomeruli and (2) inc the speed of elimination |
|
|
Term
Urine []
osmolarity range?
perfect balance?
Obligatory water loss? |
|
Definition
100 mOsm (dilute)-1200 mOsm (concentrated)
perfect balance will produce 1mL/min or isotonic urine = 300 mOsm
0.3 mL/min of urine excretion that your body has to get rid of, no matter how dehydrated one is |
|
|
Term
Medullary countercurrent system
caused by?
countercurrent multiplication system? |
|
Definition
-superficial cortical nephrons and juxtamedullary nephrons (unique anatomical arrangement)
-a vertical osmotic gradient is established by descending and ascending loops of henle |
|
|
Term
| Descending and ascending loops of henle: countercurrent multiplication |
|
Definition
-descending loop is permeable to H20 + impermeable to Na+ --> H20 reabsorbed
-ascending loop impermeable to H20 and permeable to Na+ --> Na+ reabsorbed
-bottom of loop is most [] (~1200 mOsm), top is least [] (~100 mOsm)
The loop of henle establishes the vertical osmotic gradient while the collecting duct uses the gradient to vary the osmolarity of urine |
|
|
Term
Vasopressin/ADH
produced?
released?
what triggers its release?
effect on collecting duct?
where does it act?
mech? |
|
Definition
produced by hypothalamus, released by ant. pit.
-plasma osmolarity is primary cause of ADH stim
dec BP --> dec plasma V --> inc plasma osmolarity --> inc ADH
-as you get more dehydrated, ADH allows more of the collecting duct to be permeable to H20, maxing out at 1200 mOsm
acts on collecting duct and distal tubule
second messenger system (cAMP) stimulates insertion of luminal aquaporins into mb, allowing inc H20 reabsorption |
|
|
Term
Regulation of plasma V
determined by?
regulated/sensed by?
controlled by?
what does it maintain? |
|
Definition
-determined by Na+ blance
-regulated by renal and aortic/carotid baroreceptors (act first) which sense BP
-renin angiotensin system
-maintains BP |
|
|
Term
Aortic arch + Carotid sinus
what do they sense?
how do they respond? (2) |
|
Definition
-sense short term, moment to moment changes in BP
-increase sympathetic activity by increasing renal nerve activity by (1) releasing norep + vasoconstricting afferent arteriole (dec GFR) and (2) innervating JGA by stimulating the granular cells --> release Renin |
|
|
Term
Renal baroreceptors
what do they sense?
where are they found?
what does it do? |
|
Definition
-sense long term sustained changes in BP (hemorrhage)
-found in granular cells in the JGA which sense changes in the afferent arteriole
-releases Renin |
|
|
Term
Renin
when is it released?
cascade... |
|
Definition
-when there is a dec in plasma V caused by a dec in BP
Renin catalyzes the RLS (formation) of angiotensin I from angiotensinogen, which is then converted by ACE to angiotensin II |
|
|
Term
Angiotensin II
actions? (5) |
|
Definition
1. Stims aldosterone release which increases Na+ reabsorption in distal tubule and collecting duct --> water follows
2. Stims Na+/H+ exchanger in proximal tubule which inc Na+ reabsorption --> water follows
3. Vasoconstriction of afferent arterioles --> dec GFR
4. Enhances tubuloglomerular feedback system --> dec GFR
5. Stim thirst and ADH secretion --> inc H20 comsumption and reabsorption in distal tubule and collecting ducts |
|
|
Term
Regulation of ECF Osmolarity
determined by?
detected by?
controlled by? (2) |
|
Definition
-determined by maintenance of water balance, which depends on total water-body gains and loses
-central osmoreceptors in brain (CVOs = OVLT + SFO)
- (1) ADH release from post pituitary and (2) thirst but its not a very effective mechanism |
|
|
Term
| Intersections b/w systems that control Plamsa V and Plamsa Osmolarity (3) |
|
Definition
1. Thirst can be stim by a dec in plasma V via Ang II (CVOs have receptors for Ang II)
2. Plasma V effects ADH secretion
3. Plasma V can determine the amnt of ADH released in response to an inc in osmolarity |
|
|
Term
| Other factors that affect plasma ADH and therefore plama omsolarity (3) |
|
Definition
1. Rate of ADH breakdown - metab by liver, liver disease --> inc plasma ADH
2. Significant amnts of pain, fear and trauma inc ADH release
3. Alcohol dec plasma ADH |
|
|
Term
ADH
levels?
threshold?
plasma osmolarity in healthy individuals?
when is ADH released?
% ADH release? |
|
Definition
-are always baseline levels of ADH in body
-threshold ~280 mOsm
-in healthy individuals ~290 mOsm
-plasma osmolarity >290 mOsm (becoming more [])
-1% change in plasma osmolarity --> 1 % change in plasma ADH [] |
|
|
Term
1.Mucosa (3 layers)
2.Submucosa
3.Muscularis Externa (2) |
|
Definition
a. Mucous mb: epithelial tissue that secretes mucous
b. Lamina propria: conn tissue
c. muscularis mucosa: smooth muscle cells
2. contains submucosal plexus
3.
a. inner circular muscle: contraction dec tube diameter, promotes mixing
b. outer longitudinal muscle: contraction causes tube to shorter, promotes propulsion (peristalsis) |
|
|
Term
|
Definition
-thin mb that lines abd cavities and covers organs, called the peritoneum
-intenstines infused by mesentery |
|
|
Term
|
Definition
1. Motility: muscular contractions that mixes food (segmentation) and moves it forward (peristalsis)
2. Secretion: enzymes, hormones, mucous, bile salts. Product secreted dependent upon location in GI tract. Timing of secretion controlled by NS and endocrine system
3. Digestion: of carbs, proteins and fats
4. Absorption: most important process, SI has specific mech for transporting H20, monosaccharides, FA, and AA across mucosal wall and into BV |
|
|
Term
|
Definition
-Polysaccharides (starch + glycogen) broke down by amylase --> monosaccharides (glucose, galactose, fructose)
-disaccharides (sucrose, lactose, maltose) broken down by sucrase, lactase, maltase) --> monosaccharides |
|
|
Term
|
Definition
| -Broken down by chymotrypsin, carboxypeptidase, pepsin and trypsin --> peptide fragments which are broken down by aminopeptidases --> AAs |
|
|
Term
|
Definition
| -triglycerides are broken away from their FA chain by lipase --> monoglyceride and free FAs |
|
|
Term
| What occurs in the mouth? |
|
Definition
Motility = chewing
Secretion = saliva
Digestion = by amylase, mucous and lysozymes
No absorption |
|
|
Term
| What occurs in the Pharynx/esophagus? |
|
Definition
Motility = swallowing
Secretion = mucous
No digestion No absorption |
|
|
Term
| What occurs in the stomach? |
|
Definition
Motility = receptive relaxation + peristalsis
Secretion = gastric juices --> HCl, pepsin, mucous, intrinsic factor
Digestion = carbs cont, protein begins
Absorption = no food stuff, EtOH, aspirin |
|
|
Term
| What occurs in the Pancreas? (exocrine) |
|
Definition
No motility
Secretion = Pancreatic digestive enzymes --> trypsin, chymotrypsin, carboxypeptidase, amylase, lipase + sodium bicarb soln
No digestion No absorption |
|
|
Term
| What occurs in the Liver? |
|
Definition
No motility
Secretion = Bile
No digestion No absorption |
|
|
Term
|
Definition
Motility = segmentation
Secretion = mucus pancreatic and liver secretions
Digestion = carb and protein cont, fat digestion completed
Absorption = all nutrients, most electrolytes and H20 |
|
|
Term
|
Definition
Motility = mass movements
Secretion = mucus
No digestion
Absorption = salt + H20 |
|
|
Term
| Non-digestive functions of GI tract (3) |
|
Definition
1. Excretion of waste
2. Fluid/electrolyte balance: SI absorb up to 9-11 L/day
3. Immunity: Gut Associated Lymph (GUT) which are mast cells and lymphocytes b/w epithelial cells and lamina propria. Kupffer cells in the liver that are phagocytic |
|
|
Term
Control and Reg of Digestive system via Enteric NS (
what is it?
two major networks? |
|
Definition
-very elaborate system/division of ANS, local control, very autonomous, intrinsic control of nervous and endocrine responses
1. Myenteric plexus: b/w longitudinal and circular layers of muscularis externa, regulates all gut motility
2. Submucosal plexus: in submucosal layer, controls secretion directly, absorption indirectly, and motility indirectly |
|
|
Term
| Extrinsic control of digestion? |
|
Definition
-by ANS stimulation
Parasympathetic --> inc digestion
Sympathetic --> dec digestion |
|
|
Term
|
Definition
1. Fundus: lies above gastroesophageal sphincter
2. Body: majority, contains Oxyntic mucoas
3. Antrum: bottom, where most mixing occurs due to thickest muscle walls, has pyloric gland area
4. Ends with pyloric sphincter |
|
|
Term
|
Definition
-receptive relaxation = as stomach is filled, rugae flatten out allowing V to expand w/o stretching muscle wall
-50 mL V when empty --> inc 20x |
|
|
Term
Gastric mixing
caused by?
occurs? |
|
Definition
-groups of pacemaker cells located in walls of fundus, undergo depolarizations (3/min), cause muscle contraction
-occurs in antrum |
|
|
Term
Gastric secretions
located where?
released from? |
|
Definition
-in Oxyntic mucosa (body) and pyloric glans area (antrum)
-deep gastric pits |
|
|
Term
Secretory cells in Oxyntic mucosa (4)
pernicious anemia? |
|
Definition
1. Mucous cells: secrete very thick alkaline mucous to protect stomach tissue from HCl
2. Chief cells: produce pepsinogen --> pepsin when hits gastric juice, breaks down proteins
3. Parietal cells: produce HCl and intrinsic factor (essential for B12 absorption)
4. ECL cells: produce histamine --> enhances release of HCl and pepsinogen (Paracrine effect)
-autoimmune attack against parietal cells |
|
|
Term
| Secretory cells of Pyloric gland area (2) |
|
Definition
1. G-cells: release gastrin which stims release of pepsinogen + HCl, enhances motility throughout rest of GI tract
2. D-cells: release somatostasin = beginning OFF switch (inhibits gastrin) |
|
|
Term
| Four phases of gastric secretion |
|
Definition
1. Interdigestive phase: inb/w meals, lowest in AM, highest in PM
2. Cephalic: Anticipatory for food a. (tasting, smelling, chewing, swallowing) HCl and pepsinogen released
b. gastrin released, causing histamine and HCl to be released
3. Gastric phase: food is in stomach, cues are protein, caffeine, EtOH, and distension. Gastrin, pepsinogen and HCl released
4. Intestinal phase: shuts off flow of gastric juices, somatostasin inhibits histamines, gastrin, HCl.
2. Cephalic phase: |
|
|
Term
1. Gastric Digestion (in fundus/body + antrum)
2. Gastric Absorption |
|
Definition
-cont salivary amylase + carb digestion in fundus/body
-protein digestion in antrum
-no food stuff absorption, EtOH and aspirin |
|
|
Term
Gastric emptying/motility
depends on?
gastric factors (2)
duodenal factors (4) |
|
Definition
-strength of antral peristalsis
-V of chyme, fluidity of chyme
1. Fat: digestion of fat coordinated here
2. Acidity: pancreatic enzymes neutralize HCl
3. hypertonicity: osmolarity inc due to digestion
4. distension |
|
|
Term
Gastric emptying slowed by
1. Neural response
2. Hormonal responses |
|
Definition
1. Enterogastric reflex: if pH in duodenum is 3-4, gastrin inhibited --> dec motility and dec HCl production
2. Enterogastrones
a. CCK: inhibits gastric emptying, inc pancreatic secretion, inc bile secretion
b. Secretic: inhibits gastric emptying, dec HCl secretion, inc bicarb secretion |
|
|
Term
CCK + Secretin strongest stimulators?
secreted from?
What else can effect gastric motility? |
|
Definition
CCK = fat
Secretin = presence of HCl
-duodenum
-emotions and pain |
|
|
Term
Pancreas cells (2)
-secrete what? |
|
Definition
-exocrine and endocrine (glucose + insulin)
-acinar and duct cells
Acinar: (1) trypsinogen, chymotrypsinogen, procarboxypeptidase
(2) pancreatic amylase (3) pancreatic lipase
Duct cells: secrete alkaline bicarb |
|
|
Term
Liver
produces?
canliculi?
Hepatic portal system
spincter of Oddi
CCK
Bile recirculation
strongest stim of bile production? |
|
Definition
Bile: alkaline fluid, bile salts cholesterol. Emulsifies fats, allowing lipases to further break down into micelles
-bile collecting ducts in liver
-allows hepatocytes to be in direct
contact with blood
-b/w bile duct and duodenum, opened by CCK
-opens spincter of Oddi + causes produdction of new bile
-bile reabsorbed in terminal ileum, enter portal circulation and return to liver (only 5% bile salts are excreted)
-return of old bile |
|
|
Term
| Control of bile secretion (3) |
|
Definition
1. Cholerectics: inc bile secretion
2. Hormonal: secretin
3. Neural: Vagal stimulation |
|
|
Term
SI motility depends on (3)
primary motility movement? |
|
Definition
1. Degree of distension
2. Presence of gastrin
3. Extrinsic nerve activity
-segmentation |
|
|
Term
SI mb-bound enzymes?
freq of segmentation?
crypts of Lieberkuhn?
fat absorption? |
|
Definition
9-12/min
Brush border enzymes: enterokinases + aminopeptidases (protein), dissacharisases
-contain rapidly dividing stem cells, rapdily shed, entirely epithelial lining replaced in 3 days
-thru central lacteal |
|
|
Term
SI absorption
carbs?
proteins? |
|
Definition
-are disaccharides by the time they reach the SI, further broken down by sucrase, maltase and lactase
-are single AA or small polypeptide fragments at this time |
|
|
Term
Colon
function?
sigmoid colon?
motility?
secretion? |
|
Definition
-absorb more water and salt
-at terminal end, connects to rectum
1.haustral contractions: mixing movement, similar to segmentation, enhances absorption of H20 and electrolytes
2. Mass movements: 3-4x per day, usually after meals, drives feces to the rectum
-alkaline bicarb |
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Term
1. Gastrocolic reflex
2. Gastroileal reflex
3. Defacation reflex
4. Anal sphincters (internal + external) |
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Definition
1. This is the reflex system that tells the colon to empty when food hits the stomach, or even in anticipation of a meal, caused by gastrin
2. opening of the ileocecal valve when food enters the stomach
3. distension on the rectal wall causes this
4. Internal (involuntary, external (voluntary) |
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