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Applied Physiology > Q2 Quiz #1 > Flashcards

Q2 Quiz #1 Flashcards

1
Q

What makes up the GI system?

A
  1. GI tract
  2. salivary glands
  3. exocrine pancreas
  4. liver
  5. gallbladder
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2
Q

GI fuction?

A
  1. motility
  2. secretion
  3. digestion
  4. absorption
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3
Q

What are mixing movements?

A

mix food with digestive juices and helps with digestion and absorption

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3
Q

What are dietary carbohydrates digested into?

A

monosaccharides (glucose)

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3
Q

What are the two types of digestive motility?

A
  1. propulsive movements
  2. mixing movements
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4
Q

What are propulsive movements?

A

push contents forward through digestive tract

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5
Q

What are dietary proteins digested into?

A

amino acids
small polypeptides

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6
Q

What are dietary fats digested into?

A

monoglycerides
free fatty acids

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7
Q

Most absorption is completed where?

A

small intestine

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8
Q

The intrisic nerve plexus is part of specifically what nervous system?

A

enteric nervous system

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9
Q

What does the intrinsic nerve plexus effect?

A
  1. smooth muscle
  2. exocrine gland cells
  3. endocrine gland cells
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10
Q

What does the extrinsic autonomic nerves effect?

A
  1. intrinsic nerve plexuses
  2. gastrointestinal hormones
  3. smooth muscle
  4. exocrine gland cells
  5. endocrine gland cells
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11
Q

What are some external influences of the GI regulation?

A

feeling nervous
(change bowl movement because stimulus that changes CNS can change balance of autonomic system –> change digestive system)

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12
Q

What is the swallowing reflex initiated by?

A

stimulus of pressure receptors in pharynx

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12
Q

What is the swallowing reflex controlled by?

A

swallowing center in medulla

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13
Q

What is inhibited during swallowing?

A

respiration

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13
Q

What are the two stages of swallowing

A
  1. oropharyngeal stage
  2. esophageal stage
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14
Q

What is the oropharyngeal stage?

A

moves bolus from mouth –> pharynx –> esophagus

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15
Q

What is the esophageal stage?

A

moves bolus by peristalsis through esophagus –> stomach

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16
Q

What is the peristalsis movement?

A

muscle “behind” contracts
muscle “ahead” relaxes

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17
Q

Describe gastric emptying and mixing

A
  1. peristaltic contration originates in fundus –> pyloric sphincter
  2. becomes vigorous when reach antrum
  3. strong contraction propels chyme forward
  4. small portion of chyme pushes through partially open sphincter in duodenum
  5. when peristaltic contraction reaches sphincter, it will CLOSE (no more leakage)
  6. chyme will be tossed back into antrum and will continue with each peristaltic contraction (mixing)
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18
Q

When fat is in the duodenum, what is released?

A

CCK

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18
Q

The presence of fat, acid, hypertonicity, or distension within the duodenum triggers what?

A

enterogastric reflex
release of enterogastrones
secretin, cholecytokinin

inhibit further gastric motility and emptying until duodenum has coped with factors alr present

SLOW DOWN MOTILITY (slow down the stomach for duodenum to catch up)

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19
Q

Where is the stimulation of the enterogastric reflex?

A

the small intestine

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20
Q

When acid is in the duodenum, what is released?

A

secretin

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21
Q

Which would have a higher frequency? A pacemaker at the beginning of the small intestine or a pacemaker at the end of the small intestine?

A

pacemaker at BEGINNING of small intestine

each successive pacemaker has a slightly lower frequency

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22
Q

Where does the effect of the enterogastric reflex take place?

A

in the stomach

(inhibit motility and secretion)

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23
Q

What is within the walls of the small intestine?

A

series of pacemakers

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24
Q

What is the function of the frequency “gradient”?

A

pushes chyme towards the large intestine (peristalsis)

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25
Q

What separates the large and small intestine?

A
  1. ileocecal sphincter
  2. ileocecal valve

separation is IMPORTANT bc large intestine has a lot of bacteria

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25
Q

What are the types of movement in the small intestine?

A
  1. peristalsis (push towards large intestine)
  2. segmentation (mixing back and forth with secretions throughout the intestine)
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26
Q

Where is the appendix located?

A

Lower right quadrant

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27
Q

What is the gastrocolic reflex?

A

stimulation in the stomach
effect in the colon

SIGNAL FROM STOMACH TO FORCE UNABSORBED MATERIAL THROUGH COLON TO MAKE SPACE FOR NEW MATERIAL

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28
Q

What is the duodenocolic reflex?

A

stimulate in the duodenum
effect in the colon

SIGNAL FROM THE DUODENUM TO CLEAR THE LUMEN OF THE COLON TO GET READ FOR THE FRESH CONTENT

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29
Q

What is the defecation reflex?

A

regulation of internal anal sphincter to relax

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30
Q

What type of muscle is the internal anal sphincter and is it voluntary or involuntary?

A

smooth muscle
involuntary

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31
Q

What type of muscle is the external anal sphincter and is it voluntary or involuntary?

A

skeletal
voluntary

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32
Q

The organs ____________ (upstream/downstream) in the GI tract ___________ (promote/inhibit) motility of organs ________________ (upstream/downstream) in the GI tract

A

upstream | promote | downstream
OR
downstream | inhibit | upstream

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33
Q

Is the gastro/colic reflex excitatory or inhibitory?

A

EXCITATORY

STIMULATE IN STOMACH
EFFECT IN LARGE INTESTINE

stomach sends signals that new fresh content is coming to accelerate motility of the colon

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34
Q

Is the gastro/gastric reflex excitatory or inhibitory?

A

EXCITATORY

LOCAL STIMULATION

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35
Q

Is the gastro/enteric reflex excitatory or inhibitory?

A

EXCITATORY

STIMULATE IN STOMACH
EFFECT IN INTESTINES

stomach sends signals that new fresh content is coming and promotes intestinal motility

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36
Q

Is the duodeno/colic reflex excitatory or inhibitory?

A

EXCITATORY

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36
Q

Is the gastro/ilieal reflex excitatory or inhibitory?

A

EXCITATORY

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37
Q

Is the entero/gastric reflex excitatory or inhibitory?

A

INHIBITORY

STIMULATE IN INTESTINES
EFFECT IN STOMACH

intestines stimulate that there is content in the intestines and need stomach to slow down so will decrease motility of stomach

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38
Q

What is is the secretion, major content, and digestion of the salivary gland?

A

saliva

amylase

carbohydrates

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38
Q

What is is the secretion, major content, and digestion of the esophagus?

A

N/A (secretes nothing)

mucus

N/A (digests nothing)

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39
Q

What is is the secretion, major content, and digestion of the stomach?

A

gastric juice

HCl, pepsin, intrinsic factor (IF), gastrin

proteins and lipids

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40
Q

What is is the secretion, major content, and digestion of the small intestine?

A

intestinal juice

secretin, CCK, GIP

N/A (nothing is digested)

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41
Q

What is is the secretion, major content, and digestion of the liver?

A

bile

bile salts, bilirubin

lipid

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41
Q

What is is the secretion, major content, and digestion of the pancreas?

A

pancreatic juice

NaHCO3, major digestive enzymes

carbohydrates, protein, lipids

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42
Q

What is is the secretion, major content, and digestion of the large intestine?

A

N/A (secretes nothing)

NaHCO3, mucus

N/A (digests nothing)

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42
Q

What are cells of the stomach involved in exocrine secretment?

A
  1. mucous cells (mucus)
  2. chief cells (pepsinogen)
  3. parietal cells (HCl/IF)
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43
Q

What are cells of the stomach involved in endocrine secretment?

A
  1. Enterochromaffin cells (histamine)
  2. G cells (gastrin)
  3. D cells (somatostatin)
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44
Q

What are mucous cells activated by?

A

mechanical stimulation/force by the stomach

create barrier to protect gastric mucosa

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45
Q

What are chief cells activated by?

A

ACh and gastrin

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46
Q

What are the four layers of barrier to protect the gastric mucosa?

A
  1. luminal membrane of gastric mucosal cells are impermeable to H+ (STOMACH IS HIGHLY ACIDIC)
  2. tight junction to prevent HCl penetration
  3. mucous barrier to protect gastric mucosa
  4. HCO3- rich mucus to neutralize acid
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47
Q

Where is pepsinogen stored?

A

in chief cells as zymogen granules (inactivated enyzmes)

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48
Q

What is pepsinogen activated by and what does it do?

A

HCl in lumen

digest protein into polypeptides

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49
Q

What is the function of parietal cells?

A

Secretion of HCl aka GASTRIC ACID
Secrete intrinsic factor (IF)

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50
Q

What are parietal cells activated by?

A

ACh
gastrin
histamines

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51
Q

What is the autocatalytic function of pepsinogen/pepsin?

A

POSITIVE FEEDBACK

pepsin can promote the conversion of pepsin –> pepsinogen

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52
Q

What is pH in stomach?

A

2

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53
Q

How do parietal cells produce HCl?

A
  1. protons are from water (H2O –> H+ + OH-)
  2. H+ pumped into lumen by H+-K+ ATPase pump
  3. OH- combine with CO2 –> HCO3- (carbonic anhydrase)
  4. HCO3- enters plasma by Cl- - HCO3- antiporter (secondary active transport)
  5. Cl- diffuse into lumen

NOW H+ AND Cl- ARE IN LUMEN TOGETHER
parietal cell is basically used as transporter between plasma and gastric lumen to construct HCl in lumen

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54
Q

What is pH of blood?

A

7.4

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55
Q

How to calculate [H+] in stomach relative to [H+] in blood?

A

[H+] stomach/[H+] blood

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56
Q

What are ways to reduce acid in stomach?

A

inhibit the proton pump (H+-ATPase pump)
antihistamines (to target hormones stimulating the production of acid)

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56
Q

What is the function of [H+] in stomach?

A

aids in breakdown of CT and muscle fibers
denatures proteins
kills most of microorganisms ingested with food

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57
Q

What is the main function of parietal cells releasing intrinsic factor (IF)?

A

Vitamin B12 absorption in the ileum

only at the ileum because the only one that has the receptors for vitamin B12 absorption

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58
Q

What are the gastric secretion phases?

A
  1. cephalic phase: stimulation in the head region (sight/smell/taste/thoughts) –> PARASYMPATHETIC stimulation –> salivation, etc
  2. gastric phase: food content is in the stomach, release of secretagogues (substances that promote secretion like ACh, gastrin, histamines) –> secretion of HCl, pepsinogen, and IF
  3. intestinal phase: now content flows into the duodenum (chyme in duodenum –> duodenal secretions + enterogastric reflex –> inhibit stomach motility and secretions)
  4. duodenal secretions: enterogastrones (secretin, CCK) enterokinase, and glucose-dependent insulinotropic peptide-GIP
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58
Q

What occurs when there is an absence of intrinsic factor?

A

decrease IF –> vitamin B12 deficiency –> pernicious anemia (fragile RBC = megaloblast)

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59
Q

What does gastrin do?

A
  1. increase secretion of HCl and pepsinogen
  2. enhance gastric motility and ileal motility
  3. trophic (growth effect) to the stomach and intestine mucosa
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59
Q

What causes CCK to be released?

A

protein peptides, and fat in the duodenum

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60
Q

What causes the release of secretin in the small intestine?

A

When the duodenum pH < 4.5

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61
Q

What does secretin do?

A
  1. inhibits HCl secretion in stomach
  2. inhibit gastric emptying (motility)
  3. stimulate NaHCO3 secretion to keep duodenal pH above 4.5
  4. stimulate liver to secrete bile
  5. stimulate pancreas
62
Q

What does CCK do?

A
  1. production of bile with the contraction of the gallbladder
  2. pancreatic enzyme secretions
  3. inhibiting gastric empty (motility) and gastric acid secretion (want to keep stomach full)
  4. satiety (feeling full)
63
Q

What is the process of the reabsorption of NaCl and water in the small intestine?

A
  1. Cl- uptake through K-2Cl symporter into the epithelial cells in small intestine
  2. Adenylyl cyclase activated –> generates cAMP –> activates CFTR (cystic fibrosis transmembrane)
  3. Cl- diffuses through activated CFTR (epithelial cells –> lumen)
  4. Na+ diffuses through leaking tight junctions
  5. H2O enters lumen by osmosis
64
Q

What cells in the pancreas secrete digestive enzymes?

A

acinar cells

65
Q

What cells in the pancreas secrete NaHCO3?

A

Duct cells

66
Q

What cells in the pancreas secrete insulin and glucagon?

A

Endocrine secretion Islets

67
Q

What are some protein digesting enzymes in the pancreas?

A
  1. trypsinogen
  2. chymotrypsinogen
  3. procarboxypeptidase
68
Q

The protein digesting enzymes are inactive in the pancreas. Where and what activates them?

A

DUODENUM
enterokinase (enteropeptidase) or activated trypsin

69
Q

Bile is _______________ (continuously/periodically) released by the ________ and diverted to the __________ between meals.

A

continuously
liver
gallbladder

69
Q

What is the carbohydrate digestion enzyme?

A

pancreatic amylase

70
Q

What is the process of NaHCO3 secretion in the pancreas and intestines?

A
  1. Most HCO3- enter duct cell through the Na+-HCO3- symporter
  2. Some HCO3- is generated in duct cell through carbonic anhydrase activity
  3. HCO3- enter lumen by Cl- - HCO3- antiporter or CFTR channel
  4. Na+ diffuse into lumen through leaky tight junctions

NOW Na+ AND HCO3- ARE IN THE LUMEN

71
Q

What is the fat digesting enzyme?

A

Pancreatic lipase

72
Q

What type of factor promotes the secretion of bile?

A

Choleretic factors (bile salts, CCK, secretin, and vagus nerve aka parasympathetic)

73
Q

Bile salts are recycled through what?

A

enterohepatic circulation

74
Q

What pigment causes jaundice?

A

bilirubin

75
Q

Does the pH increase or decrease or fluctuate as we go through the GI tract?

A

DECREASE
(2 in stomach –> 5 in small intestine –> 8 in large intestine)
numbers not important

76
Q

What is the enterohepatic circulation of bile salts?

A
  1. bile salts are produced in the liver and temporarily stored in the gallbladder
  2. local/hormonal/intrinsic factors stimulate the release of bile into the duodenum
  3. after job is done, 95% of bile salts are reabsorbed at the ileum (the rest is lost in the feces)
  4. reabsorbed bile salts go into the hepatic portal vein
  5. goes back to liver to be reused and recycled
77
Q

What is the pathway of absorption through the villi?

A
  1. pass through epithelial cell
  2. diffuse through interstitial fluid
  3. enter into capillary (if small enough) or lymphatic vessel (if large, will eventually merge with blood circulation)
78
Q

What are the different types of Na+ absorption?

A
  1. passive diffusion through leaky tight junctions
  2. passive diffusion through Na+ channels
  3. active transport through Na+-Cl- symporter, Na+-H+ antiporter, Na+-glucose symporter OR Na+-amino aicd symporter
  4. active transport powered by Na+-K+ ATPase pump at the basal lateral membrane
79
Q

What type of dietary carbohydrate needs to be digested more?

A

starch
glycogen

80
Q

When sodium is being absorbed, what is being created?

A

osmotic gradient

MEANS WATER WILL FOLLOW

81
Q

What enzymes digest polysaccharides?

A

salivary amylase
pancreatic amylase

82
Q

What converts disaccharides into monosaccharides (glucose/galactose/fructose)?

A

lactase
malatase
sucrase-isomaltase

83
Q

What is the process of carbohydrate absorption?

A
  1. Carbohydrates are broken down
  2. monosaccharides glucose/galactose are absorbed into epithelial cells by SECONDARY ACTIVE TRANSPORT (SGLT)
  3. fructose enters through passive facilitated diffusion (GLUT-5)
  4. monosaccharides exit cell at BASAL MEMBRANE by GLUT-2 (passive facilitated diffusion)
84
Q

What is the process of protein digestion?

A
  1. proteins are broken down into amino acids
  2. amino acids are absorbed by epithelial cells by SYMPORTER (secondary active transport)
  3. small peptides are absorbed by SYMPORTER (tertiary active transport)
  4. small peptides –> amino acids by intracellular peptidases
  5. amino acids exit cell by PASSIVE CARRIERS
  6. amino acids enter blood by SIMPLE DIFFUSION
85
Q

What is the process of fat digestion?

A
  1. triglycerides are emulsified by bile salts –> fat droplets
  2. pancreatic lipase turn triglycerides –> monoglycerides and free fatty acids
  3. water soluble micelles move to small intestine epithelial cells
  4. monoglyceride and fatty acid PASSIVELY DIFFUSE through lipid bilyaer
  5. resynthesized into triglycerides inside epithelial cells
  6. triglycerides are coated with layer of lipoprotein to produce chylomicrons
  7. chylomicrons are sent through basal membrane through EXOCYTOSIS
  8. Chylomicrons enter lymphatic vessels
86
Q

How is vitamin B12 absorbed?

A

Vitamin B12 bind to an intrinsic factor and is absorbed in the end of the ileum

87
Q

How is calcium absorbed in the small intestine?

A
  1. passively absorbed through IMCal
    OR
  2. Bind to Calbindin (calcium binding protein)
    OR
  3. actively transported through Ca2+ ATPase pump or Na+ - Ca2+ antioporter
88
Q

What is the relationship between activated Vitamin D and calcium?

A

ACTIVATED VITAMIN D ENHANCES CALCIUM ABSORPTION

89
Q

How do nutrients get to the rest of the body?

A
  1. HEPATIC PORTAL CIRCULATION –>general circulation
  2. absorbed fat enters lymphatic system –> blood circulation
90
Q

What are the two types of nephrons?

A
  1. cortical nephron (short)
  2. juxtamedullary nephron (long)
91
Q

What are the two components of a nephron?

A
  1. vascular component
  2. tubular component
92
Q

What is the vascular component of the nephron and their functions?

A
  1. afferent arteriole (blood to glomerulus)
  2. efferent arteriole (blood from glomerulus)
  3. glomerulus (capillaries that filter a PROTEIN-FREE plasma into tubular component)
  4. peritubular capillaries (exchange of ions/fluids)
93
Q

What is included in the tubular component of the nephron?

A
  1. bowman’s capsule
  2. proximal convoluted tubule
  3. loop of Henle
  4. distal convoluted tuule
  5. collecting duct
94
Q

What occurs in the Bowman’s capsule?

A

collects the glomerular filtrate
WHERE THE TUBULAR COMPONENT STARTS

95
Q

What does the proximal convoluted tubule do?

A

UNCONTROLLED reabsorption and secretion of selected substances

96
Q

What does the distal convoluted tubule and collecting duct do?

A

VARIABLE, CONTROLLED reabsorption of Na+ and H2O
secretion of K+ and H+
fluid leaving collecting duct is urine

97
Q

What are the characteristics of the cortical nephron?

A
  1. outer layer of the cortex
  2. SHORT Loop of Henle

MAJORITY OF NEPHRONS

97
Q

What does the juxtaglomerular apparatus do?

A

produces substances involved in control of kidney function

97
Q

What is the combined vascular/tubular component?

A

juxtaglomerular apparatus

98
Q

What are the characteristics of the juxtamedullary nephron?

A
  1. inner layer of cortex
  2. LONG loop of Henle
  3. Vasa recta
99
Q

Where does majority of the plasma that enters the glomerulus go?

A

EFFERENT ARTERIOLE (80%)
majority is NOT filtered and leaves through efferent arteriole

20% is filtered into PCT

100
Q

What are the three major functions of the nephron?

A
  1. glomerular filtration (PROTEIN-FREE PLASMA –> tubular component)
  2. tubular reabsorption (tubular lumen –> peritubular capillary blood)
  3. tubular secretion (peritubular capillary blood –> tubular lumen)
101
Q

How to calculate urine excretion?

A

Urine = GF - TR + TS

GF = GLOMERULAR FILTRATION
the total volume entering in for filtration

TR = TUBULAR RESORPTION
the volume that is reabsorbed from the tubular lumen –> peritubular capillary blood

TS = TUBULAR SECRETION
the volume that is excreted from the peritubular capillary blood (filtered through the SECOND time)

102
Q

How is glomerular filtrate produced?

A

When plasma is passively forced through the glomerular membrane –> Bowman’s capsule

ONLY A MINORITY GETS THROUGH

103
Q

What layers must the fluid be filtered through to get from the glomerular membrane –> Bowman’s capsule?

A
  1. endothelial cells of glomerular capillary
  2. acellular basement membrane
  3. podocytes of visceral layer of Bowman’s capsule (foot protrusions)
103
Q

What can NOT pass through the triple-layer capillary wall of the glomerulus?

A
  1. small proteins (usually filtered back into PCT by endocytosis, ex: myoglobin)
  2. large proteins (albumin/hemoglobin)
  3. negatively charged ions (basement membrane is negatively charged; WILL REPEL)
104
Q

What is the difference between the filtered fluid in the Bowman’s capsule and plasma?

A

LITTLE TO NO PLASMA PROTEINS AND NO RBC in filtered fluid

105
Q

What can get through the triple-layer capillary wall of the glomerulus?

A
  1. water
  2. small solutes (Na+, K+, amino acids, glucose, urea, etc)
106
Q

What physical forces are involved in filtration?

A
  1. glomerular capillary blood pressure (blood in glomerulus will drive filtration) (+ favor filtration)
  2. plasma-colloid osmotic pressure (proteins within capillaries will try to hold water around those proteins) (- oppose filtration)
  3. Bowman’s capsule hydrostatic pressure (tries to push fluid back into the capillaries) (- oppose filtration)
107
Q

How to calculate the net filtration pressure?

A

Glomerular capillary blood pressure - plasma-colloid osmotic pressure - Bowman’s capsule hydrostatic pressure

108
Q

Describe the glomerular capillary blood pressure.

A

Diameter of afferent is LARGER than efferent
BECAUSE EFFERENT IS SO SMALL, THE BLOOD BUILDS UP BEHIND IT (within the glomerulus)
Therefore, the blood pressure IN THE GLOMERULUS is higher than other capillaries

109
Q

What is the main force for glomerular filtration?

A

GLOMERULAR CAPILLARY BLOOD PRESSURE

110
Q

What does the glomerular filtration rate (GFR) depend on?

A
  1. net filtration pressure
  2. glomerular surface area
  3. permeability
111
Q

What is the Kf?

A

takes into account glomerular SA and permeability

112
Q

When podocytes _______________ (relax/contract), the Kf _______________ (increases/decreases). This means ______________ (more/less) filtration

A

relax/increases/more
OR
contract/decreases/less

IMAGINE A HAND PRESSING AGAINST THE MOUTH; IF TOO LOOSE, SOUND WILL STILL COME OUT; IF PLACED TIGHTER PRESSING DOWN MORE, SOUND WILL NO LONGER COME OUT

113
Q

What regulates GFR (glomerular filtration rate) and what exactly is regulated?

A
  1. autoregulation (kidney tries to control itself)
    a. myogenic mechanism (respond to pressure in vascular component)
    b. tubuloglomerular feedback (respond to salt level in filtrate)
  2. sympathetic control (control how much blood flows to the kidneys)

BOTH CONTROL GFR BY REGULATING RADIUS OF AFFERENT ARTERIOLE (how much blood flows into the glomerulus)

114
Q

What is the effect on GFR if arterial blood pressure increases WITHOUT REGULATION?

A
  1. increase arterial blood pressure
  2. increase blood flow into afferent arteriole –> glomerulus
  3. increase glomerular capillary blood pressure
  4. increase net filtration pressure (GCBP - PCOP - BCHP)
  5. increase GFR

WITHOUT REGULATION, INCREASING BLOOD PRESSURE WILL INCREASE GFR

115
Q

What is the myogenic mechanism effect during increased arterial blood pressure?

A
  1. increase arterial blood pressure
  2. smooth muscle stretches due to increased blood pressure
  3. VASOCONTRICTION
  4. decreases blood flow into glomerulus
  5. decrease glomerular capillary blood pressure
  6. decrease net filtration pressure
  7. decrease GFR

DURING THE MYOGENIC MECHANISM, THE SMOOTH MUSCLE STRETCH IS DETECTED AND VASOCONTRICTION TO PUSH AGAINST THAT STRETCH IS EMPLOYED = DECREASE AMOUNT OF BLOOD FLOWING THROUGH THE AFFERENT ARTERIOLE

115
Q

What occurs during tubuloglomerular feedback if there is an increase in GFR?

A
  1. Increased GFR
  2. more water/NaCl filtered into Bowman’s capsule
  3. travels to juxtaglomerular apparatus
  4. macula densa cells sense increased flow and NaCl
  5. MACULA DENSA CELLS RELEASE VASOCONSTRICTORS (ATP/adenosine)
  6. afferent arterioles constrict
  7. decrease blood flow through kidney/glomerulus and GFR

INCREASE GFR = INCREASED WATER/NaCl THAT GETS THROUGH TO THE BOWMAN’S CAPSULE; MACULA DENSA IN THE JUXTAGLOMERULUS APPARATUS SENSE THE INCREASE IN THOSE AND SENDS OUT VASOCONSTRICTORS; DECREASES AA –> DECREASE BLOOD FLOW THROUGH GLOMERULUS –> DECREASE GFR

116
Q

What is the myogenic mechanism effect during decreased arterial blood pressure?

A
  1. decreased arterial blood pressure
  2. smooth muscle relaxes due to decreased blood pressure within
  3. VASODILATION
  4. increase blood flow into glomerulus
  5. increases glomerular capillary blood pressure
  6. increases net filtration pressure
  7. increases GFR

THE GOAL IS TO RAISE BACK UP THE BLOOD PRESSURE SO IT VASODILATES THE AFFERENT ARTERIOLE TO INCREASE BLOOD FLOW INTO THE GLOMERULUS

117
Q

What is the difference between blood pressure changes and renal blood flow/GFR in terms of stability?

A

though blood pressure fluctuates constantly throughout the day, renal blood flow/GFR remain relatively stable though depending on the blood pressure as the blood supply

SHOWS THE IMPORTANCE AND CONSTANT AUTOGENIC REGULATION

117
Q

What occurs during tubuloglomerular feedback if there is a decrease in GFR?

A
  1. Decreased GFR
  2. less water/NaCl filtered into Bowman’s capsule
  3. travels to juxtaglomerular apparatus
  4. macula densa cells sense decreased flow and NaCl
  5. MACULA DENSA CELLS RELEASE VASODILATORS (nitric oxide/NO)
  6. afferent arterioles dilate
  7. increased blood flow through kidney/glomerulus and GFR
118
Q

What is the sympathetic control over the GFR

A
  1. increase sympathetic response –> increase heart rate –> increase arterial blood pressure –> increase GFR
  2. generalized alpha1 receptor vasoconstriction increases TPR (force of circulating blood) –> increase blood pressure –> reduces bleeding
  3. alpha1 receptor constriction of renal afferent arterioles –> decreases renal blood flow –> decrease afferent arteriole flow –> decrease GFR –> conserve body water
  4. beta1 receptor promote renin secretion from granular cells in afferent arterioles
119
Q

What is the sympathetic effect on kidneys in response to hemorrhage (bleeding)?

A
  1. decrease GFR
  2. increase salt and H2O reabsorption

tries to bring blood volume back up to normal by changing the function of the kidneys

120
Q

What is tubular reabsorption and what do the substances cross?

A

Filtrate –> plasma

  1. luminal cell membrane
  2. cystol (of luminal cell)
  3. basolateral cell membrane
  4. interstitial fluid
  5. capillary wall
121
Q

Na+ tubular reabsorption happens where?

A

EVERYWHERE THROUGHOUT THE TUBULE EXCEPT THE DESCENDING LIMB OF THE LOOP OF HENLE

121
Q

What is reabsorbed back into the peritubular capillaries?

A
  1. water (majority)
  2. sodium (majority)
  3. glucose (all of it)
  4. urea (50% of it)
122
Q

Describe sodium reabsorption in the proximal tubule?

A

secondary active transport
(moved across the membrane with another molecule X)
carrier specific

Cl- and H2O follow passively (+/- attraction and osmotic pressure)

123
Q

Describe water reabsorption in the proximal tubule?

A

AQP1 water channels OR leaky tight junction
majority of water reabsorption occurs in proximal tubule

124
Q

Where does water reabsorption occur?

A
  1. proximal tubule
  2. distal/collecting tubule (controlled by vasopressin)
  3. loop of Henle (maintains vertical osmotic gradient)
125
Q

Describe glucose reabsorption in the proximal tubule?

A

Filtered load = GFR * P(glucose)
Tm = maximum reabsorption rate of glucose/substances

126
Q

What is renal threshold?

A

PLASMA CONCENTRATION AT WHICH THE SUBSTANCE CAN BE FILTERED, IT DOES NOT MEAN THAT IT WILL BE REABSORBED

EX. IF THERE IS TOO MUCH GLUCOSE, THE TUBULAR MAXIMUM WILL BE FILTERED AND REABSORBED BUT THE REST WILL BE FILTERED AND EXCRETED

127
Q

What does tubular maximum mean?

A

WHEN ALL CARRIERS/THE MAXIMUM LOAD HAS BEEN REACHED/SATURATED

128
Q

Describe urea reabsorption in the proximal tubule?

A

urea is concentrated while passing to proximal convoluted tubules
urea PASSIVELY DIFFUSES from tubular lumen –> capillary plasma (50%)
some is excreted, some is reabsorbed back (50%)

129
Q

What is the vertical osmotic gradient?

A

solute concentrations increase from cortex –> renal papilla to facilitate the concentration of urine and reabsorption of water

130
Q

What are the parts of the loop of Henle?

A
  1. descending limb (permeable to water, NOT permeable to Na+)
    • WATER MOVES OUT OF LUMEN
  2. ascending limb (NOT permeable to water, active transport of Na+)
    • Na+ MOVES OUT OF LUMEN
131
Q

What is countercurrent flow?

A

when the current flows one way but then makes a hairpin turn and goes the opposite direction

132
Q

What is countercurrent multiplication?

A
  1. New fluid (300) goes into descending limb, pushing osmotically stable fluid (200) OUT of the ascending limb
  2. ascending limb pumps Na+ out to get back to stable (300 –> 200)
  3. continues until back to their stable osmotic level

THE ORIGINAL GOAL IS TO KEEP THE STABILITY OF EACH LIMB
DESCENDING LIMB CONCENTRATION (pump out H2O) IS HIGHER THAN ASCENDING LIMB (pump out Na+)

133
Q

What is the osmotic gradient estabilished in?

A

In the medulla by the long loop of Henle (juxtamedullary nephrons)

134
Q

The final vertical osmotic gradient is established and maintained by what?

A

ongoing countercurrent multiplication of the long loops of Henle

135
Q

Vasa recta capillaries are permeale to what?

A

NaCl
H2O

136
Q

Describe Na+ reabsorption in the distal tubules and collecting ducts.

A

Na leaky channels
regulated by renin-angiotensin-aldosterone system (RAAS)

137
Q

NaCl ____________ (retention/excretion) leads to H2O ______________ (retention/excretion)

A

retention/retention
OR
excretion/excretion

137
Q

What are the steps of releasing renin?

A
  1. Macula densa cells sense low flow and low NaCl
  2. stimulate granular cells to secrete renin
  3. granular cells secrete renin into bloodstream
    OR
  4. Granular cells sense low blood pressure in afferent arteriole
  5. granular cells secrete renin into bloodstream
138
Q

Describe the steps of the RAAS.

A
  1. ANGIOTENSINOGEN is released by the liver
  2. RENIN is produced by the kidneys and converts ANGIOTENSINOGEN –> ANGIOTENSIN I
  3. in the liver, an enzyme converts ANGIOTENSIN I –> ANGIOTENSIN II
  4. ANGIOTENSIN II in the adrenal cortex causes the release of ALDOSTERONE
139
Q

What is renin secreted in response to?

A
  1. sympathetic stimulation (beta1 receptors)
  2. reduced bp in afferent arteriole (sensed by granular cells)
  3. reduced flow/NaCl sensed y macula densa
140
Q

What are the effects of angiotensin II?

A
  1. Vasopressin (increase H2O reabsorption in kidneys)
  2. Thirst
  3. Arteriolar vasoconstriction (decrease glomerular blood pressure, decrease GFR)
  4. Production of aldosterone (increase Na+/H2O reabsorption)
141
Q

What is the effect of aldosterone on Na+ reabsorption?

A

ALDOSTERONE INCREASES Na+ REABSORPTION

secreted by adrenal cortex
increases number of Na+ leaky channels and Na+-K+ pumps in distal tubules

142
Q

Describe water reabsorption in the distal tubules and collecting ducts.

A

distal/collecting tubule impermeable to H2O
UNLESS IN THE PRESENCE OF ADH
graded effect (effect increases with the stimulation)

143
Q

What can counteract the RAAS system?

A

Natriuretic peptides

144
Q

What is the effect of ADH?

A

PROMOTES THE INSERTION OF AQUAPORINS (AQP2) INTO THE LUMINAL MEMBRANE

ADH DECREASES WATER EXCRETED AND INCREASES WATER REABSORBED

145
Q

Vasopressin (ADH) acts upon what?

A

principal cell in the distal or collecting tubule

146
Q

What is antidiuresis?

A

the process of reducing or stopping the excretion of urine
WHEN ADH/VASOPRESSIN IS PRESENT
INTRODUCES AQUAPORINS TO THE DISTAL AND COLLECTING DUCT TO ALLOW WATER TO BE LET OUT AND REABSORBED

small volume of concentrated urin is excreted

147
Q

What is the process of tubular secretion of K+?

A
  1. K+ is reabsorbed by proximal tubule
  2. K+ is secreted by principle cells in distal and collecting tubules
    OR
  3. K+ is secreted through K+ leaking channels
148
Q

What is aldosterone control on K+ secretion?

A

ALDOSTERONE INCREASE K+ SECRETION

aldosterone increases the number of Na+ leaky channels and Na+ - K+ pumps in the principal cells of distal/collecting tubules

ALWAYS PROMOTES Na+ REABSORPTION AND K+ SECRETION

149
Q

What are some stimuli for aldosterone release?

A

low ECF volume
low flow
low BP
low Na load
higher K load

ALDOSTERONE IS USED TO RESTORE OR RAISE BLOOD VOLUME

150
Q

Is the reabsorption and secretion in the proximal tubule controlled or uncontrolled?

A

UNCONTROLLED

151
Q

What controls the final amounts of H2O, Na+, K+, and H+ excreted in urine?

A

REABSORPTION AND SECRETION IN THE DISTAL TUBULE AND COLLECTING DUCT

since highly regulated, it will have the most control in regulating the levels of ions as compared to proximal absorption/secretion

151
Q

Is the reabsorption and secretion in the distal tubule/collecting duct controlled or uncontrolled?

A

CONTROLLED
regulated

152
Q

What is plasma clearance?

A

effectiveness of kidney in removing a particular substance from the plasma

153
Q

How calculate plasma clearance?

A

Clearance rate * plasma concentration of the substance

154
Q

What is clearance rate?

A

volume of plasma cleared of a particular substance each minute by the kidney

155
Q

What is the relationship between urine excretion and plasma clearance?

A

Urine excretion = plasma clearance

156
Q

How does insulin go through a nephron?

A

FOREIGN CARBOHYDRATE SUBSTANCE
FREELY FILTERED
NOT SECRETED OR REABSORBED

157
Q

What is used clinically to determine GFR?

A

Insulin (since not reabsorbed or secreted)
Creatinine

158
Q

What is the difference between insulin and creatinine in terms of GFR?

A

insulin: not secreted + not reabsorbed

creatinine: SLIGHTLY SECRETED + not reabsorbed

159
Q

If a substance is freely filtered and not secreted or reabsorbed, the GFR ____ (=, >, <) clearance rate.

A

GFR = clearance rate

160
Q

If a substance is filtered and reabsorbed but no secreted or little secretion, the GFR ____ (=, >, <) clearance rate.

A

GFR > clearance rate

161
Q

What is PAH?

A

Organic anion not naturally found in humans

161
Q

If a substance is filtered and secreted but no reabsorption or little reabsorption, the GFR ____ (=, >, <) clearance rate.

A

GFR < clearance rate

Applied Physiology (9 decks)

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