Med Phys: Unit 3 Flashcards
1
Q
Hemostasis
A
Process by which we keep blood in a fluid state and in the blood vessel
2
Q
Tissue Plasminogen Activator
A
Converts plasminogen to plasmin, which breaks up the clot
3
Q
What are the 3 components of Virchow’s Triangle?
A
Vascular components (PGI2)
Platelets
Plasma proteins
4
Q
What are the two main functions of the plasma proteins?
A
Coagulation
Fibrinolysis
5
Q
What do endothelial cells produce?
A
Prostacyclins (PGI2)
6
Q
What do prostacyclins do?
A
Cause smooth muscle cells to relax and stay open
7
Q
Why do blood clots appear red?
A
Red blood cells are trapped
8
Q
What enzyme converts phospholipids to arachadonic acid?
A
Phospholipase
9
Q
What enzyme converts arachadonic acid to leukotrienes, and what cells have this enzyme?
A
Lipoxygenase in mast cells
10
Q
What enzyme converts arachadonic acid to an intermediate product?
A
Cyclooxygenase
11
Q
What enzyme converts the intermediate product to thromboxanes, and what cells have this enzyme?
A
Thromboxane synthetase in platelets
12
Q
What enzyme converts the intermediate product to prostacyclins, and what cells have this enzyme?
A
Prostacyclin synthetase in endothelial cells
13
Q
What enzyme converts the intermediate product to prostaglandins, and what cells have this enzyme?
A
Prostaglandin synthetase in mast cells
14
Q
What do prostaglandins do?
A
Cause dilation, increased vascular permeability, pain
Can lead to laryngeal edema, swelling in airway, narrowed space
15
Q
What do prostacyclins (PGI2) do?
A
Vasodilation
Decrease platelet aggregation
16
Q
What does thromboxane do?
A
Vasoconstriction
Increase platelet aggregation
17
Q
What stimulates platelets to produce thromboxanes?
A
Thromboxane synthetase is activated when they recognize an injured vessel and stick to the underlying collagen
18
Q
What do leukotrienes do?
A
Cause airway narrowing (bronchoconstriction) by causing smooth muscles to contract
19
Q
What did leukotrienes used to be called?
A
Slow Releasing Substance of Anaphylaxis
20
Q
Why did people have a rebound after being treated for an allergic reaction?
A
Mast cells produce leukotrienes and the process takes a while, so the rebound was due to the leukotrienes
21
Q
What is the initial allergic reaction due to?
A
The allergic substance binds to IgE on mast cells, which immediately release histamine
22
Q
What is Aspirin?
A
An irreversible cyclooxygenase inhibitor
23
Q
Why shouldn’t asthmatics take Aspirin?
A
Since it inhibits cyclooxygenase, mast cells can’t produce prostaglandins and can only produce leukotrienes, which will constict the airway
24
Q
What is Motrin?
A
A reversible cyclooxygenase inhibitor
25
What does low-dose (81mg) Aspirin do?
Blocks the platelets' ability to make thromboxane but have minimal effect on endothelial cells' ability to make PGI2
26
Why does low-dose Aspirin affect platelets more than endothelial cells?
Endothelial cells have a nucleus and will keep producing cyclooxygenase, but platelets do not
27
What 2 types of medications are available for asthmatics to act on the leukotriene pathway?
```
Enzyme inhibitors (Zyflo)
Leukotriene D-receptor inhibitors (Singulair)
```
28
Where are chemoreceptors located?
Carotid bodies and the aortic arch
29
What stimulates chemoreceptors?
Low O2
CO2 excess
H+ excess
30
What results when chemoreceptors are activated?
VMC excites the vasoconstriction area to increase sympathetic activity, vasoconstrict, and increase BP to increase HR and SV to get more O2 to the brain and heart
31
At what systolic pressure is the CNS ischemic response activated?
<60 mmHg
32
What systolic pressure activates the CNS ischemic response the greatest?
15-20 mmHg
33
Where are the low pressure (stretch) receptors located?
Atria and pulmonary arteries
34
What stimulates the stretch receptors?
Increases in blood volume
35
What are some of the mechanisms that the stretch receptors can use to lower blood pressure?
Decrease ADH
Increase ANP
Increase glomerular filtration rate
Decrease Na+ reabsorption
36
How would decreasing ADH lower blood pressure?
Fewer aquapores to decrease water reabsorption at the kidneys, excrete more water, decrease blood volume
37
How would increased ANP lower blood pressure?
Decreases the kidneys' ability to reabsorb Na+
38
What is Natricor and how does it work?
Recombinant ANP given via IV to decrease blood volume by excreting more Na+ (H2O follows)
39
What is BNP and what does it do?
Brain natriuretic peptide is released from ventricles when they are stretched to decrease Na+ reabsorption in the kidneys
40
What is the Bainbridge reflex?
Increases in atrial pressure (atrial stretch) decrease vagal afferents to the VMC to allow greater SNS output, which increases HR and contractility
41
What are the 4 steps of hemostasis?
Vasoconstriction
Primary hemostasis
Secondary hemostasis
Thrombus & antithrombotic events
42
Name some of the autocoid factors responsible for contraction in the "vasoconstriction" phase of hemostasis.
Thromboxane
ADP
Ca++
43
What are some mechanisms that favor thrombosis?
Exposed collagen (to bind platelets)
Increased release of vWF (to stick platelets together)
Increased tissue factor release (to initiate coag cascade)
44
How do PGI2, NO, and ADPase inhibit thrombosis?
Prevent platelet aggregation
45
How does thrombomodulin inhibit thrombosis?
Binds to thrombin to convert protein C to activate C, which blocks some coag proteins (factor 5a and 8a)
46
How does Heparin sulfate inhibit thrombosis?
Binds to anti-thrombin3 to block thrombin from forming a fibrin clot
47
How does the tissue factor pathway inhibitor inhibit thrombosis?
Inactivates tissue factor 7a and 10a to inhibit the extrinsic pathway
48
Where are platelets formed, and from what cell?
In the bone marrow from megakaryocytes
49
What is a normal level of platelets?
150,000-400,000 cells / microL
50
What percentage of platelets are stored in the spleen?
30%
51
What happens if someone's spleen is removed?
That person doesn't have that storage site for platelets, so they will have an increased # of circulating platelets
52
What structures are in the Peripheral Zone of the platelet?
Glycocalyx
Plasma membrane
Phospholipids (where thromboxane is produced)
53
What structures are in the Sol-Gel zone of the platelet?
Microtubules like actin and myosin, and thrombosthenin
54
What is thrombosthenin?
A stimulant for actin and myosin crossbridge formation
55
What structures are in the Organelle Zone of the platelet?
Dense granules (with Ca++)
Alpha granules
Lysosomes
Mitochondria
56
What are 2 problems with stents?
They're thrombogenic
| Can get overgrowth of the endothelium over the stent
57
What can activate platelets?
```
Collagen (negatively charged)
ADP
Thromboxane
Platelet activating factor
Epi
Thrombin
```
58
What are the 3 steps of platelet activation?
Adhesion
Secretion
Aggregation
59
What glycoprotein assists with adhesion?
Glycoprotein 1b, which binds to vWF to link platelets to collagen
60
What glycoprotein assists with aggregation?
Glycoprotein 2b3a... It changes shape in the presence of Ca++ to become a receptor for fibrinogen, which links platelets to platelets
61
What does Plavix do?
An ADP receptor antagonist to prevent ADP from binding and activating platelets
62
What is deficient in Glansmann thrombasthenia?
GP2b3a, no aggregation
63
What is deficient in Bernard-Soulier syndrome?
GP1b, platelets don't adhere
64
What is deficient in von Willebrand disease?
vWF, platelets don't adhere
65
How do NSAIDs inhibit platelets?
Reversibly inhibit COX
66
How does the GP2b3a receptor inhibit platelets?
Inhibits fibrinogen and vWF binding
67
What is Integrelin and when is it given?
GP2b3a receptor antagonist given via IV for chest pain, inhibits fibrinogen binding
68
What does a platelet count test tell us?
The number of platelets
69
What is the definition of thrombocytopenia?
Fewer than 100,000 platelets per microL
70
What do bleeding time and aggregation studies tell us?
The function of platelets
71
What is the normal range for bleeding time?
2.5-7.5 minutes
72
How would Aspirin affect bleeding time?
Prolonged bleeding time, 4-21 minutes
73
What chemicals are used in the aggregation studies?
Epi
ADP
Collagen
74
What is Ristocetin?
Acts like an adhesion agonist
75
If light shines through the aggregometer, are platelets activated or non-activated?
Activated and aggregated
76
What results from a platelet count < 70,000?
Elevated bleeding time
77
What results from a platelet count 20,000-50,000?
Increased post-traumatic bleeding
78
What results from a platelet count <20,000?
Spontaneous bleeding
79
What could prolong an individual's bleeding time?
Thrombocytopenia
Qualitative problems (protein issue)
Vascular disorders
80
What is a zymogen?
An inactive enzyme precursor
81
Why do you draw blood into a tube with a Ca++ chelator, and what are 2 examples of a Ca++ chelator?
Sodium citrate or EDTA bind the Ca++ so the blood won't clot
82
What happens if you have a problem with protein C or protein S?
You'll clot and won't be able to stop
83
What happens in Factor V Leiden mutation?
Factor V is still a working cofactor for clot formation, but is resistant to inactivation by protein C
84
What percentage of the Dutch population has Factor V Leiden mutation?
10%
85
What do platelets release during "secretion"?
```
Dense and alpha granules
ADP
thromboxane
PDGF
Ca++
```
86
What kind of platelet problem do you have if you get an abnormal Ristocetin?
An adhesion problem (GpIb or vWF deficiency)
87
What kind of platelet problem do you have if you get an abnormal Epi, ADP, or collagen aggregation study result?
An aggregation problem (GpIIbIIIa deficiency)
88
If a person on Coumadin starts taking antibiotics which decrease Vitamin K absorption, how would that affect their INR?
INR would increase
89
What percentage of total body weight is water?
Total body water is 60% of total body weight
90
What percent of total body water is Intracellular?
2/3 TBW
91
What percentage of total body water is Extracellular?
1/3 TBW
92
What percentage of ECF is in interstitial fluid?
2/3-3/4 ECF
93
What percentage of ECF is in the plasma?
1/4-1/3 ECF
94
What has higher water content, muscle or fat?
Muscle
95
Who has higher water content, men or women?
Men
96
Who has higher water content, young or elderly?
Young
97
Who has higher water content, obese or normal weight?
Normal weight
98
Do infants have a higher or lower % of water?
Higher, but they can lose it quickly
99
What factors cause infants to lose water quickly?
High metabolic rate
Increased body surface/weight ratio
Decreased renal function
100
How do the osmoreceptors react to decreased osmolarity?
Decreased frequency AP
Decreased amount of ADH
Excrete more water
101
How do the osmoreceptors react to increased osmolarity?
Increased frequency AP
Increased ADH
Reabsorb more water
102
What stimulates the release of ADH/vasopressin?
Increased osmolarity
| Decreased blood volume (decreased perfusion to hypothalamus)
103
What stimulates the release of aldosterone?
Renin is most potent stimulus
K+ levels not very efficient
Decreased blood volume is least efficient
104
How does renin stimulate the release of aldosterone?
Converts angiotensinogen to angiotensin when stimulated by low BP
105
How does K+ stimulate the release of aldosterone?
If K+ levels are high, aldosterone is released independently of renin as blood runs through the adrenal glands to lose K+ in urine and reabsorb Na+
106
What stimulates the release of ANP?
Increased volume in the atria
107
How is fluid intake regulated?
```
By osmolarity (thirst mechanism)
and habits
```
108
How is electrolyte intake regulated?
By dietary habits, food preferences
109
How are fluid and electrolyte output regulated?
By the kidneys
110
How are plasma and interstitial fluid different?
Plasma has more protein (greater oncotic pressure) and higher concentration of cations (attracted to negatively charged protein)
111
What determines fluid distribution across capillary membranes?
Hydrostatic and oncotic pressures
112
What determines fluid distribution across cell membranes?
Osmolarity
113
What defines an isoosmotic glucose solution?
5% glucose
114
What defines an isoosmotic NaCl solution?
0.9% NaCl (saline)
115
What are two irregularities of fluid balance that can lead to hypernatremia?
Increased H2O loss
| Na+ excess (increased Na+ intake)
116
What are two irregularities of fluid balance that can lead to hyponatremia?
Water excess
| Increased Na+ loss (Na+ wasting disease)
117
What can rapid cell shrinking in the brain lead to?
Can tear vessels and cause hemorrhage
118
What can rapid cell swelling in the brain lead to?
Can cause herniation because the brain cannot increase volume by more than 10% before moving down foramen magnum
119
How do cells respond to extracellular hypertonicity in chronic situations?
Gradually increase genes that code for proteins to increase intracellular osmolarity to prevent shriveling up
120
What are some proteins that can be produced to increase intracellular osmolarity?
Na+/H+ membrane transporters
| Enzymes (aldose reductase)
121
What has a greater effect on cell volume and clinical physiology: rapid or slow changes in ECF osmolarity?
Rapid changes have a greater effect
122
Which type of diabetes results in an increase in glucose over the course of decades?
Type II
123
How would "central" diabetes insipidus lead to dehydration?
Lack of ADH, less aquapores in the kidney, can't reabsorb water, excrete large amounts of water
124
How would "nephrogenic" diabetes insipidus lead to dehydration?
Kidneys don't respond to ADH, no aquapores produced, can't reabsorb water, excrete large amounts of water
125
How does Primary aldosteronism lead to hyperosmotic overhydration?
Producing a ton of aldosterone means reabsorbing a ton of Na+, and H2O with it
126
How does Cushing's Syndrome lead to hyperosmotic overhydration?
Too much cortisol is produced, which has aldosterone-like activity, so you retain Na+, are thirsty, and retain H2O too
127
What can complicate hyperosmotic overhydration?
Hypokalemia. Since they're retaining so much Na+, they're excreting more K+, which leads to less excitable cells
128
What are some conditions that could cause chronic vomiting, leading to hypo-osmotic dehydration?
Crohn's disease
| Salmonella poisoning
129
How does Addison's disease lead to hypo-osmotic dehydration?
Decreased aldosterone means you're not reabsorbing Na+, excreting it via urine, and H2O follows
130
What are two conditions that can lead to inappropriate ADH syndrome?
Bronchogenic tumors
| Fibrosing tuberculosis lung lesions
131
How does SIADH lead to hypo-osmotic overhydration?
Too much ADH means too many aquapores are formed at the kidneys, too much water is reabsorbed
132
How does circulatory failure lead to hypo-osmotic overhydration?
The left side of the heart doesn't move blood forward, so SV decreases, MAP decreases, decreased renal BP releases aldosterone to reabsorb Na+, but reabsorb more H2O than Na+ (fluid backs up in lungs as well)
133
How does hyponatremia affect fluid movement?
Fluid moves into the cell, intracellular edema
134
How does hypothyroidism affect fluid movement?
Don't kick Na+ out when it accumulates in the cells, intracellular edema
135
Is edema mainly in ECF or ICF?
ECF, but can involve ICF as well
136
What causes intracellular edema?
Depression of metabolic system (hypothyroidism)
| Lack of adequate nutrition to cells (ischemia)
137
What causes extracellular edema?
Abnormal leakage from plasma to interstitium (leaky capillaries)
Lymphatic failure
138
Of what is pitting edema indicative?
Fluid and protein accumulation
139
What can lead to edema?
Increased capillary hydrostatic pressure
| Decreased capillary oncotic pressure
140
What can lead to increased capillary hydrostatic pressure?
Heart failure
Local venous obstruction (DVT)
Increased Na+ and water intake
141
How does left sided heart failure lead to edema?
Blood builds up in the L atrium and lung vessels, increased hydrostatic pressure pushes fluid to interstitial space in lungs (pulmonary edema)
142
How does right sided heart failure lead to edema?
Fluid backs up in peripheral vessels (peripheral edema)
143
What is one common manifestation of right sided heart failure in men?
After lying flat for a while, men can experience scrotal swelling
144
What is one common manifestation of right sided heart failure in men?
After lying flat for a while, men can experience scrotal swelling
145
What two disorders can lead to decreased oncotic pressure?
```
Liver failure (not making proteins)
Renal disease (nephrotic syndrome)
```
146
How does edema present from hypoproteinemia?
Mostly in the eyelids and is morning-dominant
147
How does edema present from left sided heart failure?
Pulmonary edema that is worse at night, makes it harder to breathe
148
How does edema present from right sided heart failure?
Peripheral edema that is evening-dominant
149
Why is it important for the kidneys to excrete urea?
NH4+ is converted to urea in the liver and excreted via urine. If the liver cannot do this, NH4+ builds up and is toxic to the brain (hepatic encephalopathy)
150
What can uric acid accumulation indicate?
Uric acid comes from nucleic acid metabolism and is excreted via urine. High amounts of uric acid can indicate leukemia because fast cell turnover produces a lot of uric acid.
151
What can creatinine accumulation indicate?
The kidneys are supposed to get rid of it, so it can be used to predict glomerular filtration rate
152
Where does unconjugated bilirubin accumulate, and what can accumulation indicate?
Deposits in fat tissues (sclera) and can indicate liver problems, because it is conjugated in the liver
153
How would renal disease affect erythropoietin?
People with renal disease wouldn't be making erythropoietin, so they would need injections of recombinant to get blood levels back up
154
What did they used to give instead of recombinant erythropoietin to stimulate RBC production?
Testosterone, which is why males have more RBCs than females
155
What is the difference between D2 and D3 vitamin D?
D2 has a shorter half life than D3
156
If someone took a vitamin D supplement once a week, should they take D2 or D3?
D3 since D2 has a shorter half life
157
If someone had diarrhea, how would that affect the acid/base balance?
Lose lots of HCO3- that was from the pancreas to neutralize stomach acid, person would become acidic, kidneys needs to correct it by excreting H+ ions
158
How would vomiting affect the acid/base balance?
Lose acid, relative increase in HCO3-, kidneys need to get rid of it
159
Why can gluconeogenesis by the kidneys be a problem?
Kidneys make glucose from amino acids (proteins)m and the kidneys aren't going to work well if you lose too much protein
160
What is the major arterial pressure regulator?
The renin-angiotensin system
161
What else contributes to arterial pressure regulation?
Prostaglandins (vasodilation) and the kallikrein-kinin system
162
How long will it take for the kidneys to correct a 10x increase in Na+ intake?
2-3 days
163
Where are the nephrons located?
In the cortical and medullary regions
164
Describe blood flow through the kidney.
```
Renal artery
Interlobular arteries
Arcuate arteries
Interlobular arterioles
Afferent arterioles
Glomerulus
Efferent arteriole
```
165
Describe the pressure in the glomerular capillaries.
High hydrostatic pressure, about 60 mmHg, which promotes filtration to Bowman's space
166
Describe the pressure in the peritubular capillaries.
Low hydrostatic pressure, about 13 mmHg, which promotes reabsorption
167
What percentage of cardiac output do the kidneys receive?
22% or 1100 mL/min
168
What is the filtration rate?
Filter about 125 mL/min
169
At what age and what rate do we lose nephrons?
After age 40 lose 10% of nephrons every 10 years
170
What percentage of nephrons are cortical, and what is their importance?
70-80%
| filtration, getting rid of waste
171
What percentage of nephrons are juxtomedullary, and what is their importance?
20-30%
| Develops an osmotic gradient in medullary interstitial space that allows us to concentrate our urine
172
Does the detrusor relax or tighten to expel urine?
Tightens
173
Which nerves control the internal urethral sphincter?
Autonomics
174
Which nerves control the external urethral sphincter?
Motor neurons
175
Why do you only empty 1000 mL of urine from a bladder at a time?
The blood vessels surrounding the stretched bladder are pretty closed, and they would become engorged with blood, BP could bottom out
176
What percentage of blood flow is filtered in the kidneys?
20%
