case 2: acute pancreatitis Flashcards
1
Q
blood - plasma
A
- Fluid portion of the blood, 55% of blood volume
- Dissolved ions – Na+ (major) and others
- Plasma proteins (7-9%, gm/dl) -> colloid osmotic pressure (P) (direct relationship)
– Albumins – ~60%, produced by the liver, mainly for colloid osmotic
P and buffering blood pH
– Globulins – α & β globulins (produced by liver, transport of lipids &
fat-soluble vitamins; γ globulins (immunoglobulins)
2
Q
Blood – Formed Elements
A
- RBC (erythrocytes) – flattened
biconcave discs
– Hemoglobin (Hb) – O2 & CO2
– No nuclei, no mitochondria
– Produce 300 x 109 RBCs each day
– ♂ – 5.1-5.8; ♀ – 4.3-5.2 (106/mm3) - Buffy coat – platelets & WBC
- WBC - body defense and immunity
– Granulocytes – eosinophils, basophils (fewest); neutrophils
(polymorphonuclear, PMN; 50-70% WBC)
– Agranulocytes – monocytes & lymphocytes (immune) - Thrombocytes (platelets) (not WBC) – fragments of megakaryocytes
3
Q
Leukocytosis & Left Shift
A
- WBC = 16.1K with left shift (normal = 4.0-10.9K)
- Neutrophils – Left vs. Right Shift
– Organ of origin is bone marrow
– Lifespan – hours (infection present) to ~2 weeks (no infection) - first line of defense
*increase in WBC = infection/inflammation, bacteria infection
*decrease in WBC (leukopenia) = viral infection
*left shift in neutrophils = young, singular large nucleus morphing to/from semilunar shape
* right shift/normal neutrophil = older, 3-5 lobes (leaflets)
4
Q
What is the relationship between high respiratory rate (R.R.)
(20/min; normal 12-16) and the low O2 saturation rate (88%)?
A
- breathing shallow = not a lot of O2 into lungs
- smoking
5
Q
Does the O2 saturation rate (88%) cause hypoxemia and hypoxia?
A
hypoxemia = lower O2 amount in blood
hypoxia = lower O2 for body’s need
6
Q
Forms of O2 Transport
A
- O2 is transported in the blood in two forms:
– Dissolved form in plasma – directly responsible for PO2 in blood
– Combined with hemoglobin (Hb-O2) (oxyhemoglobin) in RBC – O2 bound to Hb, does not
contribute to PO2 - Loading and unloading of the blood O2
- This is a sequential process – O2 molecules are dissolved first, the
dissolved O2 diffuse to RBC, then bind to Hb
Dissolved O2 in blood
plasma (generates PO2)
(Hb-O2 does not generates PO2)
7
Q
Dissolved O2 in Blood Plasma
A
- The solubility of O2 = 0.003 ml/dl
blood/mmHg (each 100 cc of blood/mmHg only dissolves .003 ml of O2, O2 not very soluble in blood plasma compared with CO2) - How much O2 is dissolved in the
systemic arterial blood plasma if
PaO2 is 100 mm Hg?
– What is the PO2 in the systemic
arterial blood (PaO2)?
– Amount of O2 dissolved in plasma =
Solubility (ml/dl blood/mm Hg) x
PaO2
– = .003 ml /dl blood/mm Hg x 100
mm Hg = .3 ml O2/dl blood - How much O2 is dissolved in the
systemic venous blood if the PvO2 is
40 mmHg?
.003 x 40 = .12 ml O2/dl blood
*100 mmHg in O2 blood
*40 mmHg in deO2 blood
8
Q
O2 Capacity (O2 Carrying Capacity )
A
- O2 capacity is the maximal (theoretical) amount of O2 bound to Hb (100% saturation, every molecule of Hb bound to O2)
– Each gm of functional Hb binds 1.34 ml ml O2 (1.34 ml / gm Hb)
– O2 capacity only depends on Hb concentration in the blood, higher the gm = higher O2 capacity
– O2 capacity (ml/dl blood) = (gm Hb/dl blood) x (1.34 ml O2/gm Hb) - What is the normal hemoglobin concentration?
– Men – 13.5-17.5 gm/dl; Women – 12.0-15.5 gm/dl. Why? males secrete testosterone which stimulates production of Hb
– What is the O2 capacity in patients with anemia? Hb reduced, so O2 reduced.
Polycythemia? Hb high so O2 high but the disadvantage is it increases workload on the heart
– What is the advantage and disadvantage for having high or low O2 capacity ?
high O2 capacity means a more O2 for various needs like metabolic or athletic activity, low O2 capacity means person cannot sustain strenuous activity for long periods of time
9
Q
Hb Saturation Rate
A
- Hb saturation rate depends on
PO2 - Physiologically, Hb saturation
rate will never be able to reach
100% - Hb is not fully saturated at 100
mmHg PO2 but rather at ~97%
saturation - As blood leaves peripheral
tissues after gas exchange, PO2
is 40 mmHg; Hb is ~ 75%
saturated
fresh air = higher PO2 in air, more O2 exchange into blood, 95-100 PO2 mmHg ( but after unloading, reduced to 40)
10
Q
O2 Content
A
- O2 content (O2 concentration) is the total, actual amount of O2 in the blood
(plasma & RBC together) - O2 content = dissolved O2 + O2 bound with Hb
– Dissolved O2 = (PO2 x solubility of O2 in blood)
– O2 bound with Hb = O2 capacity (ml/dl blood) x saturation rate (%) - O2 content of a normal subject (PaO2 = 100 mmHg; [Hb] = 15 gm/dl blood):
– The solubility of O2 in plasma is 0.003 ml O2/mmHg/dl blood -> the amount of
dissolved O2 = 0.003 ml O2/mmHg/dl blood x 100 mmHg = 0.3 ml/dl blood
– Hb-O2 = 1.34 ml/gm Hb x 15 gm x 97% = 19.5 ml/dl arterial blood (venous blood = 75%)
– O2 content = 0.3 ml (dissolved O2) + 19.5 ml (Hb-O2) = 19.8 ml/dl blood
– % of dissolved O2 accounts for 0.3 ml/19.8 ml x 100 = 1.5%
– -> > 98% of O2 transported in the blood is in Hb-O2 form - Relationship between dissolved O2 and Hb-O2
– Dissolved O2 accounts for < 2% of O2 content, yet O2 needs to be dissolved in
the plasma first to be transported into RBC to form Hb-O2, i.e. O2 used for
binding with Hb is from the dissolved form - higher pressure = more o2 dissolved in blood plasma
- o2 dissolved more readily than co2
- amount dissolved o2 depends on o2 solubility in blood
- pressure higher in systemic arterial blood than venous bc pco2 in arterial is higher. more o2 in systemic arterial blood. unloading o2 reduces pco2 and extra amount o2 present in Hb = o2 capacity x saturation rate
- venous blood o2 capacity = 75%
- arterial blood O2 capacity = 97%
11
Q
Hb-O2 Dissociation Curve
A
- X-axis denotes PO2 (mm Hg), Y-axis denotes O2 saturation rate (%) or
O2 content (ml O2 /dl blood) - (Left panel) -> The higher the PO2, the higher Hb-O2 saturation rate
- (Right panel) -> The curve of “total” and the curve of Hb-bound almost
overlap, why?
greater than 98% of O2 transported in the blood of O2 content is bc of O2 saturation bound to Hb
12
Q
Volume of O2 Unloaded to Tissues
A
- O2 content of a normal subject (PaO2 = 100 mmHg; [Hb] = 15 g/dl blood):
– O2 content in arterial blood = 0.3 ml dissolved + 19.5 ml in Hb = 19.8 ml/dl
– O2 content in venous blood = 0.12 ml dissolved + 15.1 ml in Hb = 15.2 ml/dl
– O2 content unloaded to the peripheral tissues = 19.8 -15.2 = 4.6 ml/dl blood - O2 content of this patient (PaO2 = 100 mmHg; [Hb] = 15 g/dl blood):
– Hb-O2 = 1.34 ml/gm Hb x 15 gm x 88% = 17.7 ml/dl arterial blood
– O2 content in arterial blood = 0.3 ml dissolved + 17.7 ml in Hb = 18.0 ml/dl
– O2 content in venous blood = 0.12 ml dissolved + 15.1 ml in Hb = 15.2 ml/dl
– O2 content unloaded to the peripheral tissues = 18.0 -15.2 = 2.8 ml/dl blood
– 2.8 ml/4.6 ml = 61% of O2 unloading amount, compared with the normal - Does the O2 saturation rate (88%) cause hypoxemia and hypoxia?
– Yes, 61% of O2 normal unloading amount results in hypoxemia and hypoxia
cyanosis
13
Q
Volume of O2 Unloaded to Tissues
A
- O2 content of a normal subject (PaO2 = 100 mmHg; [Hb] = 15 g/dl blood):
– O2 content in arterial blood = 0.3 ml dissolved + 19.5 ml in Hb = 19.8 ml/dl
– O2 content in venous blood = 0.12 ml dissolved + 15.1 ml in Hb = 15.2 ml/dl
– O2 content unloaded to the peripheral tissues = 19.8 -15.2 = 4.6 ml/dl blood - O2 content of this patient (PaO2 = 100 mmHg; [Hb] = 15 g/dl blood):
– Hb-O2 = 1.34 ml/gm Hb x 15 gm x 88% = 17.7 ml/dl arterial blood
– O2 content in arterial blood = 0.3 ml dissolved + 17.7 ml in Hb = 18.0 ml/dl
– O2 content in venous blood = 0.12 ml dissolved + 15.1 ml in Hb = 15.2 ml/dl
– O2 content unloaded to the peripheral tissues = 18.0 -15.2 = 2.8 ml/dl blood
– 2.8 ml/4.6 ml = 61% of O2 unloading amount, compared with the normal - Does the O2 saturation rate (88%) cause hypoxemia and hypoxia?
– Yes, 61% of O2 normal unloading amount results in hypoxemia and hypoxia
cyanosis
14
Q
Amylase and Lipase Tests
A
- Amylase
– For digestion of starch (polysaccharides) into disaccharides
(maltose)
– Sources of amylase – saliva, pancreas & others (muscle, liver etc.) - Lipase (pancreatic lipase)
– For digestion of triacylglycerol (triglyceride, neutral fat) into
monoacylglycerol & fatty acids
– Sources of lipase – pancreas (main) & stomach - Pancreatitis, commonly causes high levels of amylase and lipase
in the bloodstream
Amylase and Lipase Tests
15
Q
Liver Enzymes – ALT & AST
A
- ALT & AST – screen hepatocellular injury
– ALT (alanine transaminase, or serum glutamate-pyruvate
transaminase, SGPT)
– AST (aspartate transaminase, or glutamate-oxaloacetate
transaminase, SGOT) - AST/ALT ratio – [AST] in blood/ [ALT] in blood
– Very useful to differentiate causes of liver damage
– ALT is liver specific, AST is present in multiple organs
– An AST/ALT ratio of 2:1 or greater indicate alcoholic liver disease
Liver Enzymes – ALT & AST
present in liver and muscle
