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Physiology > Lecture Exam 4 > Flashcards

Lecture Exam 4 Flashcards

1
Q

Nutrient undergo what before absorption?

A

digestion

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2
Q

What two things aid digestion & absorption?

A

motility & secretion

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3
Q

Where does absorption occur?

A

GI lumen

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4
Q

Where does secretion occur?

A

endocrine & exocrine glands

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5
Q

Path of the GI tract

A
  1. mouth
  2. pharynx
  3. esophagus
  4. stomach
  5. small intestine
  6. colon
  7. rectum
  8. anus
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6
Q

What do hepatocytes in the liver secrete?

A

bile

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7
Q

What are the 2 main functions of the liver?

A

remove old RBC’s (catalyzes Hb & generates bilirubin)
eliminates wastes & toxins

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8
Q

What stores bile?

A

gallbladder
makes bile more concentrated & ejects it into the small intestine when needed

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9
Q

What transports bile from the liver or gallbladder to the duodenum for digestion?

A

common bile duct

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10
Q

The common bile duct joins with the pancreatic duct to form what?

A

ampulla of Vater

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11
Q

What regulates flow from the pancreas & gallbladder to the duodenum?

A

sphincter of oddi

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12
Q

Materials to make bile are taken up from blood in the what?

A

sinusoids
(similar to capillaries)

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13
Q

What drain into the bile ducts?

A

canaliculi

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14
Q

What do the bile ducts drain into?

A

common hepatic duct

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15
Q

What are the most common forms of carbohydrates?

A

disaccharides or polysaccharides

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16
Q

In order for carbohydrates to be absorbed, what form must they be in?

A

monosaccharide
(glucose, galactose, fructose)

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17
Q

What digests starch (carbohydrates)?

A

amylase
(salivary or pancreatic)

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18
Q

What are the 2 ways glucose & galactose (monosaccharides carbohydrates) are absorbed?

A

apical membrane: secondary active transport
basolateral membrane: facilitated diffusion

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19
Q

How is fructose (monosaccharide carbohydrate) absorbed?

A

apical & basolateral membrane: facilitated diffusion

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20
Q

In order for proteins (peptides) to be absorbed, what forms must they be in?

A

amino acids
dipeptides
tripeptides

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21
Q

What proteases break down proteins (peptides) for digestion?

A

endopeptidases
exopeptidases
zymogens

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22
Q

What is the FIRST site of protein digestion?

A

gastric pits in the stomach

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23
Q

What enzyme does the stomach lumen secrete?

A

pepsin

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24
Q

What does pepsin do?

A

breaks down peptides (proteins) into a form that the body can digest

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25
Q

What is pepsinogen?

A

the inactive form of pepsin

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26
Q

What cells in the stomach secrete pepsinogen?

A

chief cells

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27
Q

What cells in the stomach secrete acid in order to activate pepsinogen?
(acid activates pepsinogen into pepsin)

A

parietal cells

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28
Q

How are amino acids (form of proteins) absorbed?

A

apical membrane: facilitated diffusion or Na+ linked secondary active transport
basolateral membrane: facilitated diffusion

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29
Q

How are dipeptides & tripe-tides (form of proteins) absorbed?

A

apical membrane: active transport
basolateral membrane: broken down into amino acids & use facilitated diffusion

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30
Q

What is the most common form of lipids in a typical diet?

A

triglycerides

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31
Q

Typical diet contains how many g of lipids a day?

A

50 g of lipids a day

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32
Q

Typical diet contains how many g of proteins a day?

A

125 g of proteins a day

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33
Q

Typical diet contains how many g of carbohydrates a day?

A

500 g of carbs a day

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34
Q

What do lipases do?

A

break down triglycerides into monoglycerides
digest lipids

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35
Q

What are the 4 events that are ESSENTIAL for digestion & absorption of lipids?

A
  1. secretion of bile & lipases
  2. emulsification
  3. enzymatic hydrolysis
  4. micelle formation
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36
Q

What secretes lipases?

A

pancreas

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37
Q

What form should lipids be in for absorption?

A

micelle

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38
Q

What are the 3 functions of bile salts?

A
  1. emulsify lipid
  2. form micelle
  3. remove waste products
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39
Q

What molecules within the fat droplet can lipases act on?

A

only molecules near the edge of fat droplet

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40
Q

Describe absorption of monoglycerides & fatty acids

A
  1. micelle absorbed by simple diffusion
  2. enter smooth ER, reform triglyceride
  3. enter Golgi, packaged into chylomicrons
  4. exocytosis
  5. chylomicrons enter lymphatic system
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41
Q

How are vitamins A, D, E, & K (fat-soluble) absorbed?

A

vitamins dissolve in lipids & are absorbed with them

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42
Q

What do water-soluble vitamins need in order to be absorbed?

A

special transport proteins

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43
Q

Vitamin B12 must be bound to what in order to be absorbed?

A

an intrinsic factor

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44
Q

Where is sodium absorbed?

A

actively absorbed in jejunum, ileum, & colon

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45
Q

How is chloride absorbed?

A

passively follows sodium absorption

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46
Q

How is potassium absorbed?

A

passively absorbed

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47
Q

How are bicarbonate ions absorbed in the jejunum?

A

passively absorbed

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48
Q

In the ileum & colon, how are bicarbonate ions secreted?

A

secreted in exchange for chloride ions

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49
Q

Where is calcium absorbed?

A

actively absorbed in duodenum & jejunum

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50
Q

What does calcium require for absorption?

A

vitamin D
increases concentration of calcium-binding protein thus increases calcium absorption

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51
Q

Describe the process of calcium absorption

A
  1. calcium binds to calcium-binding protein
  2. transported into epithelial cells
  3. transported out across basolateral membrane by Ca2+ pump
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52
Q

What secretes transferrin & where is it secreted?

A

secreted by enterocytes into lumen of the small intestine

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53
Q

What does transferrin do?

A

binds iron for transport through blood or into cells

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54
Q

Describe process of iron absorption

A
  1. transferrin binds iron
  2. complex binds receptor
  3. taken into cells by receptor-mediated endocytosis
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55
Q

Iron is stored as what in enterocytes?

A

ferritin

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56
Q

Is water absorption active or passive?

A

passive

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57
Q

Where is water absorbed?

A

small intestine & colon

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58
Q

What does the hepatic artery do?

A

supplies O2 to the liver

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59
Q

What does the hepatic PORTAL vein do?

A

delivers nutrients from mesenteric veins to the liver

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60
Q

What does the hepatic vein do?

A

delivers nutrients from the liver to the heart

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61
Q

Where are GI hormones secreted?

A

from endocrine cells in the stomach & small intestine

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62
Q

Where is gastrin secreted & what does it do?

A

secreted in stomach
stimulates gastric secretions

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63
Q

Where is cholecystokinin (CCK) secreted & what does it do?

A

secreted in duodenum & jejunum
stimulates pancreatic enzyme secretion
stimulates bile secretion
stimulates gallbladder contraction
inhibits gastric secretion

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64
Q

Where is secretin secreted & what does it do?

A

secreted in duodenum & jejunum
stimulates pancreatic bicarbonate secretion
inhibits gastric secretion

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65
Q

Where is GIP secreted & what does it do?

A

secreted in duodenum & jejunum
stimulates insulin secretion by pancreas
inhibits gastric secretion

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66
Q

The hormone leptin is release from what?

A

adipose (fat) cells

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67
Q

When leptin (hormone) is released, what does it cause?

A

an increase in metabolism
a decrease in hunger

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68
Q

What hormone regulates food intake?

A

leptin

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69
Q

When orexigenic factors are released, what does it cause?

A

an increase in hunger
a decrease in metabolism

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70
Q

Satiety factors (fullness) causes the release of what?

A

alphaMSH
CART

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71
Q

Orexigenic factors (hunger) causes the release of what?

A

NPY
AgRP
ghrelin (produced in stomach when its empty)

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72
Q

What 2 enzymes are present in saliva?

A

salivary amylase (carb digestion)
lysozyme (anti-bacterial)

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73
Q

Characteristics of saliva

A

rich in bicarbonate ions
contains mucus
has enzymes present

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74
Q

What kind of saliva is produced under parasympathetic activation?

A

watery saliva

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75
Q

What kind of saliva is produced under sympathetic activation?

A

thick, protein-rich saliva

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76
Q

Where are gastric pits located?

A

in stomach lining

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77
Q

What is the first place of digestion for lipids & carbohydrates?

A

the mouth

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78
Q

Acid (HCl) & pepsinogen secretion in the stomach is regulated by what?

A

parasympathetic nervous system

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79
Q

What cephalic phase stimuli activate PNS & increase acid, pepsinogen, & gastrin secretion?

A

sight, smell or taste of food
chewing & swallowing

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80
Q

Where does cephalic phase stimuli originate?

A

in the head
requires CNS input

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81
Q

Where does gastric phase stimuli originate?

A

in stomach

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82
Q

Where does intestinal phase stimuli originate?

A

in small intestine

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83
Q

What gastric phase stimuli increase acid, pepsinogen, & gastrin secretion?

A

proteins & digestion products being in the stomach
dissension of stomach

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84
Q

What inhibits secretion in the gastric phase (stomach)?

A

exit of food
increased acidity in stomach

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85
Q

What portion of the pancreas produces pancreatic juice?

A

exocrine portion

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86
Q

What cells secrete pancreatic juice?

A

acinar & duct cells

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87
Q

What are the primary stimulants of pancreatic juice & bile secretion?

A

CCK & secretin

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88
Q

CCK stimulates what kind of cells?

A

acinar cells
to contract gallbladder & eject bile into duodenum

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89
Q

Secretin stimulates what kind of cells?

A

duct cells
to secrete more bile

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90
Q

What is the function of GI motility?

A

mix & propel GI tract contents

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91
Q

GI motility is due primarily to contractions of the what?

A

muscularis externa (outer muscle layers)

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92
Q

What does peristalsis do?

A

propels contents forwards

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93
Q

What does segmentation do?

A

mixes contents

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94
Q

Define segmentation

A

type of motility of the small intestine
alternating contractions between intestinal segments

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95
Q

Define bolus

A

chewed food + saliva

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96
Q

Process of swallowing reflex

A
  1. bolus arrives at inferior esophagus
  2. lower esophageal sphincter relaxes
  3. bolus enters stomach
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97
Q

What initiates the swallowing reflex?

A

tongue moving bolus to pharynx

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98
Q

What factors affect the gastric emptying rate?

A

volume of chyme in the stomach
strength of gastric peristalsis

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99
Q

Secretion of what increases the force of gastric motility?

A

gastrin

100
Q

Secretion of what decreases the force of gastric motility?

A

CCK
secretin
GIP

101
Q

What cephalic phase (head) stimuli increase gastric motility?

A

anger, aggression

102
Q

What cephalic phase (head) stimuli inhibit gastric motility?

A

pain, fear, depression

103
Q

What gastric phase (stomach) stimuli increase gastric motility?

A

distension of stomach

104
Q

What intestinal phase (intestine) stimuli inhibits gastric motility?

A

distension of duodenum

105
Q

Gastric means…

A

of the stomach

106
Q

What increases motility in the small intestine?

A

distension

107
Q

Define intestino-intestinal reflex

A

injury or severe stress that inhibits intestinal contractions

108
Q

Define oleo-gastric reflex

A

distension of ileum inhibits gastric motility

109
Q

Define gastro-ileal reflex

A

presence of chyme in stomach increases motility in ileum

110
Q

In the colon, what mixes contents?

A

haustrations

111
Q

In the colon, what propels bolus towards rectum?

A

mass movement

112
Q

Define colono-colonic reflex

A

distension of colon in one area causes relaxation of other areas

113
Q

Define gastro-colic reflex

A

food in stomach increases colonic motility

114
Q

What enzyme turns dextrins into glucose?

A

dextrinase

115
Q

What enzyme turns polysaccharides into glucose?

A

glucoamylase

116
Q

What enzyme turns sucrose into fructose & glucose?

A

sucrase

117
Q

What enzyme turns lactose into galactose & glucose?

A

lactase

118
Q

What enzyme turns maltose into 2 glucose?

A

maltase

119
Q

What are the functions of the urinary system?

A

regulate plasma ionic composition
regulate plasma volume
regulate plasma osmolarity
regulate plasma pH
remove waste products from plasma
secrete erythropoietin & renin
activate vitamin D3 & calcitrol

120
Q

What is the functional unit of the kidney?

A

nephron

121
Q

What 2 things make up the nephron?

A

renal corpuscle & renal tubules

122
Q

What 2 things make up the renal corpuscle?

A

glomerulus
glomerular (Bowmans) capsule

123
Q

What is the glomerulus?

A

the capillary network for filtration

124
Q

What does the glomerular (Bowmans) capsule do?

A

receives the filtrate & inflow to renal tubules

125
Q

What are the 4 renal tubules?

A

proximal tubule
loop of henle
distal convoluted tubule
collecting duct

126
Q

What 2 things make up the proximal tubule?

A

proximal convoluted tubule
proximal straight tubule

127
Q

What 3 things make up the loop of henle?

A

descending limb
thin ascending limb
thick ascending limb

128
Q

What makes up the distal convoluted tubule?

A

connecting tubule

129
Q

What makes up the cortical nephron?

A

short loop of henle

130
Q

What makes up the juxtamedullary nephron?

A

long loop of henle

131
Q

What is responsible for the medullary osmotic gradient?

A

juxtamedullary nephron

132
Q

What 2 nephron produce urine?

A

cortical & juxtamedullary nephron

133
Q

Define filtration

A

flow of protein free plasma from glomerular capillaries into the bowmans capsule

134
Q

Define reabsorption

A

selective transport of solute & water from renal tubule to interstitial fluid

135
Q

Define secretion

A

selective transport of solute & water from interstitial fluid into renal tubule

136
Q

What are the 3 barriers that filtrate must cross to enter the capsule?

A

capillary endothelial layer
surrounding epithelial layer (podocytes)
basement membrane

137
Q

Define filtration fraction

A

fraction of blood filtered by the kidneys
GFR/renal plasma flow (found as %)

138
Q

What starling forces FAVOR filtration?

A

glomerular capillary hydrostatic pressure (60 mmHg)
bowmans capsular oncotic pressure (0 mm Hg)

139
Q

What starling forces OPPOSE filtration?

A

bowmans capsular hydrostatic pressure (15 mm Hg)
glomerular oncotic pressure (29 mm Hg)

140
Q

The kidneys account for how much of cardiac output at rest?

A

20%

141
Q

What is typical renal blood flow amount?

A

625 ml/min

142
Q

What is typical GFR amount?

A

125 ml/min or 180 L/day

143
Q

What is typical filtration rate amount?

A

3 L/day

144
Q

Define filtered load

A

amount of a substance filtered by the kidneys

145
Q

How many liters of urine is excreted per day?

A

1.5 L

146
Q

What percentage of filtered fluid is reabsorbed?

A

99%

147
Q

A small increase in GFR causes a large increase in what?

A

large increase in volume of fluid filtered & excreted

148
Q

How does increasing mean arterial pressure affect GFR?

A

increase in MAP increases GFR

149
Q

What happens during myogenic (intrinsic) regulation of GFR?

A
  1. an increase in pressure activates mechanoreceptors
  2. smooth muscle contracts
  3. decrease in radius, increase in resistance
  4. GFR increase
150
Q

How does tubuloglomerular feedback affect intrinsic regulation of GFR?

A

macula densa cella secrete paracrine factors when flow increases
this causes smooth muscle to contract, increasing resistance, & increasing GFR

151
Q

How does extrinsic control directly effect GFR?

A

decreases in BP decreased filtration pressure thus decreases GFR

152
Q

How does extrinsic control indirectly affect GFR?

A

decreases in BP decreases blood volume, decreases MAP, decreases GFR

153
Q

Where does the majority of solute reabsorption occur?

A

proximal tubule (PCT)

154
Q

Where is reabsorption regulated?

A

distal tubule (DCT) & collecting ducts

155
Q

Where is reabsorption unregulated?

A

proximal tubule (PCT)

156
Q

What are the 2 barriers for reabsorption & secretion?

A

epithelial cells of renal tubules
endothelial cells of capillaries

157
Q

How are solutes reabsorbed?

A

through active & passive reabsorption

158
Q

How is water reabsorbed?

A

through osmosis, it follows the solute

159
Q

Define transport maximum

A

the rate of transport when carriers are SATURATED

160
Q

Define renal threshold

A

solute concentration in the plasma when carriers are saturated & the solute first appears in the urine

161
Q

Why is there no glucose in the urine of healthy patients?

A

because 100% of glucose will be reabsorbed

162
Q

Where is glucose freely filtered?

A

glomerulus

163
Q

Where is glucose actively reabsorbed?

A

proximal tubules (unregulated)

164
Q

During secretion what direction does solute move?

A

peritubular capillaries into tubules

165
Q

What are secreted substances?

A

potassium
hydrogen
choline
creatinine
penicillin

166
Q

Where does water conservation happen?

A

nephron loop

167
Q

Why is the proximal tubule the mass reabsorber & nonregulated?

A

it has leaky junctions & a large surface area

168
Q

Why do the distal tubule & collecting ducts have regulated reabsorption & secretion?

A

they have tight junctions that limit paracellular transport

169
Q

Define excretion rate

A

amount of a solute exerted in the urine over time

170
Q

What does the amount of solute excreted depend on?

A

filtered load
secretion rate
reabsorption rate

171
Q

If the amount of solute excreted per minute is less than the filtered load, the solute was…

A

reabsorbed

172
Q

If the amount of solute excreted per minute is greater than the filtered load, the solute was…

A

secreted

173
Q

Define clearance

A

the volume of plasma from which a substance has been completely removed

174
Q

What is the clearance of inulin?

A

125 mL/min

175
Q

What does the clearance of inulin tell us?

A

tells us about the clearance of a substance that is freely filtered
this is the GFR value

176
Q

What is at the clearance of glucose?

A

0 ml/min

177
Q

What is renal blood flow value?

A

1136 ml/min

178
Q

If clearance is GREATER than GFR, the solute was what?

A

solute was secreted

179
Q

If clearance is LESS than GFR, the solute was what?

A

solute was reabsorbed

180
Q

Where is urine formed?

A

in the renal tubules

181
Q

What give control over urination?

A

sphincters

182
Q

What is the flow of urine?

A

kidney, ureters, bladder

183
Q

Define balance

A

solutes & water enter & exit plasma at the same rate
quantity stays the same

184
Q

Define positive balance

A

solute or water ENTERS plasma faster than it exits
quantity INCREASES

185
Q

Define negative balance

A

solute or water EXITS plasma faster than it enters
quantity decreases

186
Q

Regulation of renal excretion depends on what 2 things?

A

the late distal tubule & collecting ducts

187
Q

What cells in the late distal tubule & collecting ducts regulate balance of water & electrolytes?

A

principal cells

188
Q

What cells in the late distal tubule & collecting ducts regulate acid-base balance?

A

intercalated cells

189
Q

What establishes the medullary osmotic gradient?

A

water reabsorption in the proximal tubule

190
Q

Define normovolemia

A

normal blood volume

191
Q

Define hypervolemia

A

high blood volume

192
Q

Define hypovolemia

A

low blood volume

193
Q

What is the osmolarity of body fluids?

A

300 mOsm

194
Q

What organ alters osmolarity of extracellular fluid?

A

kidneys

195
Q

Is water reabsorption an active or passive process?

A

passive
happens through osmosis

196
Q

Where is 70% of filtered water reabsorbed?

A

proximal tubules

197
Q

Where is 20% of filtered water reabsorbed?

A

distal tubules

198
Q

What hormones regulate water reabsorption in the distal tubules?

A

ADH (vasopressin) and aldosterone

199
Q

When being reabsorbed, water follows what?

A

the solute
this is why it is passive

200
Q

What establishes the osmotic gradient for water reabsorption?

A

Na+ being actively transported across the basolateral membrane

201
Q

What establishes the medullary osmotic gradient?

A

the countercurrent multiplier

202
Q

The medullary osmotic gradient is dependent on what?

A

the loop of henle

203
Q

What part of the loop of henle is permeable to water & has NO transport of Na+, Cl-, or K+?

A

the descending loop

204
Q

What part of the loop of henle is impermeable to water & has active transport of Na+, Cl-, and K+?

A

the ascending loop

205
Q

Where is 10% of filtered water reabsorbed?

A

collecting ducts

206
Q

What hormone regulates water reabsorption in the collecting ducts?

A

ADH

207
Q

Water reabsorption in the distal tubule & collecting duct is dependent on what?

A

the medullary osmotic gradient that is established by the countercurrent multiplier & epithelium permeability to water

208
Q

What is water permeability dependent on?

A

water channels (aquaporins)

209
Q

Where is aquaporin 3 always present?

A

in basolateral membrane

210
Q

Aquaporin 2 is present where & under what conditions?

A

present in apical membrane only when ADH is present in blood

211
Q

How does ADH affect water reabsorption?

A

it promotes water reabsorption & reduces urine volume
it stimulates insertion of aquaporin 2

212
Q

Where is ADH secreted from?

A

posterior pituitary (after stimulation from hypothalamus)

213
Q

How does increased extracellular fluid osmolarity affect ADH?

A

it increases ADH

214
Q

How does decreased baroreceptor activity affect ADH?

A

it increases ADH

215
Q

If blood pressure drops below 80 mmHg what happens to GFR, water filtered, & water excretion?

A

decrease in GFR
decrease in amount of water filtered
decrease in water excretion

216
Q

If blood pressure increases to more than 180 mmHg what happens to GFR, water filtered, & water excretion?

A

increase in GFR
increase in amount of water filtered
decrease in water excretion

217
Q

Define hypernatremia

A

high plasma sodium

218
Q

Define hyponatremia

A

low plasma sodium

219
Q

What is the primary solute in extracellular fluid?

A

sodium

220
Q

Sodium is critical for what 2 things?

A

normal osmotic pressure
function of excitable cells

221
Q

What does aldosterone do?

A

it increases sodium reabsorption

222
Q

How does aldosterone increase sodium reabsorption?

A

it acts on principal cells of distal tubules & collecting ducts to increase the number of Na/K pumps on the basolaterla membrane and Na+, K+ channels on the apical membrane

223
Q

What organ secretes angiotensinogen?

A

the liver

224
Q

What turns angiotensinogen into angiotensin 1?

A

renin

225
Q

What turns angiotensin 1 into angiotensin 2?

A

ACE

226
Q

What stimulates aldosterone production?

A

angiotensin 2

227
Q

What 3 factors increase renin release?

A
  1. decrease in BP in afferent arteriole
  2. increase in renal sympathetic nerve activity
  3. decreased Na+ and Cl-
228
Q

What cells secrete ANP (atrial natriuretic peptide)?

A

atrial cells

229
Q

ANP is secreted in response to what?

A

atrial wall stretch
patients with heart failure will show high levels of ANP

230
Q

An increase in ANP causes what chain of events?

A

increase in afferent arteriole radius
decrease of efferent arteriole radius
increase in glomerular pressure
increase in GFR
increase in Na+ EXCRETION
increased urine volume

231
Q

Where is K+ freely filtered?

A

glomerulus

232
Q

Where is K+ reabsorbed?

A

proximal & tubules

233
Q

Where is K+ secreted?

A

distal tubules & collecting ducts

234
Q

Which hormone affects K+ secretion?

A

aldosterone
an increase in aldosterone release = an increase in K+ secretion

235
Q

Define hypercalcemia

A

high plasma calcium

236
Q

Define hypocalcemia

A

low plasma calcium

237
Q

Why is calcium balance critical?

A

it triggered exocytosis, secretion, and muscle contraction

238
Q

Where is the majority of calcium reabsorbed?

A

in the proximal tubules

239
Q

Where is the rest of calcium reabsorbed?

A

loop of henle & distal tubules

240
Q

Reabsorption of Ca2+ in the loop of henle & distal tubules is regulated by what 2 hormones?

A

parathyroid hormone (PTH)
calcitonin

241
Q

How does parathyroid hormone (PTH) affect [Ca2+]?

A

it increases Ca2+ reabsorption thus increasing plasma [Ca2+]

242
Q

How does calcitonin affect [Ca2+]?

A

it decreases plasma [Ca2+]

243
Q

How does a decrease in blood pressure & blood volume affect ADH?

A

it increases its secretion

244
Q

Where is aldosterone secreted?

A

adrenal gland

245
Q

How does a decreased in blood pressure and blood volume affect ADH?

A

it increases its secretion

Physiology (11 decks)

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