Hemorrhage & Sock Flashcards
What is the result if chronic hemorrhage?
Leading to anemia and may be hypotension, but it may reflect a serious disease.
Describe the body responsed to loss of different blood percentages.
Less than 10%, no significant effect on COP or ABP, as blood donation.
10-20%, variable degrees of compenated hemorrahgic shock occurs
>20%, the shock becomes uncompensated
>30%, the shock becomes irreversible
What is the aim of body compensatory mechanisms in shock?
Correct drop in ABP and blood volume.
Mention Immediate compensatory reactions that correct ABP
- Diminished rate of discharge of impulses from arterial & atrial baroreceptors
- Chemoreceptors stimulation
- CNS ischemic response
- Increased production of Ang II & ADH
Mention effect of Diminished rate of discharge of impulses from arterial & atrial baroreceptors
- VC of arterioles ex brain & heart, leading to pale and cold skin, dec GFR & diminished urine volume.
- Venoconstriction to inc VR & COP
- INC symp discharge to heart inc rate & contractility, a rapid weak pulse.
- Inc symp discharge to adrenal medulla & inc CA which stimulate reticular formation causing restlessness & inc VR due to inc muscle tone.
Describe mechanisms if stimulation of chemoreceptors
- Diminished blood flow to aortic & carotid bodies (less than 80 mmHg)
- Hypoxia produces lactic acid & H+
- PO2 less than 60 mmHg
Describe results of chemoreceptor stimulation
Inc sympathetic discharge to heart & vessels & dec vagal tone
Stimulation of rapid breathing & rapid shallow breathing
GR: CNS ischemic reflex is active below ABP 60 mmHg
Because that us the lower limit if the range of cerebral autoregulation
Describe effect of Ang II
Arteriolo p4 & venoconstriction, thirst sensation, inc aldosterone (thus inc Na+ reabsorption)
Describe effect if ADH in shock
VC & inc blood volume by dec urine output
Mention mechanisms to correct blood volume in shock (short-term)
Capilary fluid shift phenomenon
Plasma protiens are restored by movement of labile tissue and liver proteins to plasma
RBCs are restored by contraction of splenic capsule
Mention mechanisms to correct blood volume in shock (long-term)
- Plasma volume is restired within 12-72 hrs by thirst & hormonal conservation
- Plasma proteins are replaced by hepatic synthesis 3-4 days
- RBCs are 4-8 weeks due to inc release of erythropoietin hormone leading to inc in erythropoiesis
Define circulatory shock
It is acute decrease in tissue perfusion so that the amount of O2 & nutients reaching the the cells is not sufficient to maintain life processes particularly in vital organs like brain & heart.
GR: ABP is not a good measure for progression of shock
Because ABP is strongly defended by several regulatory mechanisms, as decrease in ABP would be compensated by more VC which dec tissue oerfusion and priduce more shock.
Write a short note on hypovolemic shock
It is due to dec in volume of circulating blood, due to blood loss as in hemorrhage, plasma loss in burns, nody fluid loss in vomiting & diarrhea.
The heart is normal but VR and thus COP is reduced, compensation is through VC of splanchnic & skeletal muscle BVs.