Block 3 Exam Med Phys Review

Question 1

What are the three main pressures in circulation?

Answer 1

Driving Pressure – Pressure along axis
Hydrostatic – Pressure due to gravity
Transmural - Pressure along the vessel walls

Question 2

Explain the Bernoulli Effect in relation to blood.

Answer 2

The Bernoulli effect states that liquid flows from areas of high to low energy and not just pressure. The total amount of energy in a closed system should remain constant. Therefore, energy at one point must be equal to energy at another point within the same vessel.
Equation for energy in Bernoulli’s formula is (Pressure energy) = Driving Pressure + (1/2)ρVelocity^2
So setting two points with different pressures equal to one another
P1+(1/2)* ρVelocity^2 = P2+(1/2) ρ*Velocity^2
The velocity in the narrower part of the vessel must increase its velocity to continue blood flow.

Question 3

Explain a way to remember capillary Pressure when given pre and post pressure in the arterial and venous side.

Answer 3

The more pressure exerted by the arterial side the less important it is for capillary pressure to be increased. However, if pressure on the venous side is too high the capillary pressure must increase to push the blood through.

Question 4

Explain Distensibility, Compliance, and Elastance

Answer 4

Distensibility is the overall amount in which a vessel can stretch it is the Y value on a Relative Volume vs. Pressure graph.
Compliance is how easy it is to increase the volume of a vessel given any amount of additional pressure it is the slope of a Relative Volume vs. Pressure graph.
Elastance is how much bounce back, resistance, or ability a vessel must return to its original shape.

Question 5

Compare and Contrast Distensibility, Compliance, and Elastance in Arteries and Veins

Answer 5

Arteries and Veins have similar distensibility and are both able to stretch relatively high. However due to the arteries lower compliance it takes more pressure to do so whereas a vein requires very little pressure to fully distend. Arteries with have more elastance to bounce back into shape but a vein will kind of sag when pressure is removed.

Question 6

Why is a vein so compliant at lower pressure?

Answer 6

Because at a lower pressure a vein does not exhibit a transmural force as it goes from small squashed oval shape into a round vein.

Question 7

Explain the Youngs Modulus

Answer 7

Youngs modulus is a number identifying how stiff a material is. The higher the Young’s modulus the less compliant the material and therefore the less stress is needed to break the material.

Question 8

Explain vessel tension and how it relates to arteries, veins, and blood pressure.

Answer 8

Pressure = Tension/Radius so Tension = Pressure * Radius
As the radius of a vessel increases, because of increased blood volume or pressure, the tension along the walls of the vessel increases. Within an artery the tension changes in an upward curve that is relatively steep, however veins do not show much tension until a rather high radius is achieved at which point the tension curves upward steeply. However due to the prolonging of the vein’s tension relation the slope of the average of tension vs. radius for veins is much shallower.

Question 9

How do vessel components effect tension?

Answer 9

The more elastic fibers found within a vessel the more it can withstand a high tension. Collagen fibers however undergo tension rather quickly. A vessel’s ability to withstand volume change and its effect on its tension is related to the ratio of collagen and elastin fibers. Balance between these two types of fibers help maintain vessel stability when blood volume and pressure change dramatically.

Question 10

What mechanism controls capillary blood flow the most?

Answer 10

Precapillary resistance is the most responsible for changing capillary blood flow. Precapillary resistance is determined by the resistance within arterioles which have vascular smooth muscle and can contract to increase resistance.

Question 11

Explain the different types of capillaries and their functions.

Answer 11

There are three main types of capillaries continuous, fenestrated, and sinusoidal discontinuous. The amount that each capillary can filter out is directly proportional to the number of openings exist within endothelial cells.

Question 12

Explain oxygen diffusion patterns of capillaries within oxygenated tissue.

Answer 12

From the arterial side to the venous side O2 levels decrease along the axis of the capillary. Likewise radiating outward from the capillary, the amount of O2 delivered to the tissue dissipates the farther from the capillary.

Question 13

What is Fick’s Principal what can it tell us about blood flow?

Answer 13

Fick’s Principal states that if the oxygen concentration before an organ on the arterial side and the oxygen concentration on the veinous side are known, along with the organs extraction ratio, blood flow can be determined.
[O2]a-[O2]v = Qo2/F
Flow = Qo2/[O2]a-[O2]v
A similar principal can be applied to determine the amount of solute flow, on average, within an organ happens at any spot of a capillary.

Question 14

Explain Starling Forces and how water would move with each changed parameter.

Answer 14

The main starling forces are transmural pressure caused by blood pushing onto vessel walls and oncotic pressure caused by solutes within the vessel pulling water.
Capillary Pressure causes water to leave the capillary and oncotic pressure would pull water into the capillary.
Filtration is water leaving the capillary and absorption is water flowing into the capillary.

Question 15

What are the two main kinds of vascular smooth muscle control? What can they be further broken up into?

Answer 15

Central
- Autonomic nervous system
- Hormones
Local
- Myogenic
- Metabolic
- Endothelial

Question 16

Explain neurotransmitter receptors and molecules responsible for vasoconstriction and vasodilation.

Answer 16

Vasoconstriction
- Sympathetic Nervous System
o Alpha 1 Receptors Norepinephrine
o Alpha 2 Receptors Norepinephrine
o Sympathetic Cotransmission
 Alpha 1 and Alpha 2 Receptors detect Norepinephrine, ATP, and Neuropeptide Y
Vasodilation
- Sympathetic Nervous System
o Beta 2 Receptors Epinephrine
- Parasympathetic
o Muscarinic Receptors Acetylcholine
o Parasympathetic Cotranmission
 Muscarinic Receptors Acetylcholine, Nitric Oxide, and VIP

Question 17

Explain the Endocrine and Paracrine systems of vasoconstriction and vasodilation.

Answer 17

Vasoconstriction
- AT-1 Receptors Angiotensin II
- V1R Receptors Arginine Vasopressin
- 5-HT Receptors Serotonin
- Y1R Receptors Neuropeptide Y
Vasodilation
- H2 Receptors Histamine
- VIPR1&2 Receptors VIP
- NPR1 Receptors ANP

Question 18

Explain Myogenic Tone Regulation.

Answer 18

Myogenic tone regulation is triggered by the stretch of vascular smooth muscle cells. When the VSMC is stretched it opens nonselective cation channels that depolarize the cell and opens voltage gated calcium channels which increase the concentration of calcium.

Question 19

What is the main effect on vascular smooth muscle caused by the presence of metabolites? The effect when absent? Why?

Answer 19

Increasing amounts of metabolites or decreasing vital resources like oxygen causes vasodilation within the surrounding blood vessels and tissue. This is because high amounts of metabolites indicates that the local tissue is metabolically active and needs a large supply of blood to maintain its metabolic need, and by vasodilating metabolites can be taken away from the cells and filtered out.
When metabolites are not present around the cell this indicates that the cell is not currently in need of large amounts of blood and therefore undergoes vasoconstriction to shunt most of the blood away to areas of the body that require it.

Question 20

Name the local tissue factors associated with metabolic regulation of vascular smooth muscle tone.

Answer 20

Increase in these within the extracellular fluid causes vasodilation.
- [pCO2]
- [K+]
- [Lactate]
- [ATP]
- [ADP]
- [Adenosine]
Decrease in these within the extracellular fluid causes vasodilation.
- [pO2]
- pH
Decrease in this within the intracellular fluid causes vasodilation.
- [ATP]

Question 21

Explain endothelial regulation of vascular tone.

Answer 21

Endothelial cells release either endothelin or nitric oxide to regulate vascular tone. Endothelin is a vasoconstrictor while Nitric oxide is a vasodilator.

Question 22

Explain the advantage the aorta has with the pulsatile nature of the cardiac cycle.

Answer 22

Due to its compliance the aorta can function as a reservoir between heartbeats to help maintain blood flow so that blood flow does not change rapidly with each beat.

Question 23

Know the basic structural features of the heart & vessels.Describe how blood flows through the heart & vasculature to pass through
both circuits (pulmonary & systemic) in series.

Answer 23

Heart is made of right and left atrium and right and left ventricles. Blood flow from circulation to circulation goes right atrium -> Tricuspid Valve -> Right ventricle -> Semilunar Valve -> Pulmonary Arteries -> Lungs -> Pulmonary Veins -> Left Atrium -> Mitral Valve -> Left Ventricle -> Aortic Valve -> Aorta -> Arteries -> Veins -> Vena Cava

Question 24

Explain why circulation through organs is in parallel arrangement (vs. series) &
how this allows independent regulation of blood flow.

Answer 24

Parallel configuration allows for the blood to reach multiple different parts of an organ and shunt or limit blood from one area to another.

Question 25

Explain how flow through an ideal tube approximates blood flow & how radius,
length, & fluid viscosity affect flow.

Answer 25

Length and viscosity lower blood flow as they increase but radius increases blood flow by a power of 4

Question 26

Describe how transmural & hydrostatic pressure, varying vessel
compliance/radius, & the pulsatile nature of the heart pumping affects flow.

Answer 26

Bounceback caused by transmural pressure helps regulate shifting amounts of blood flow and blood pressure. Pumping of the heart helps stabilize blood as it is effected by gravity as is the case with hydrostatic pressure.

Question 27

Explain how changes in viscosity, vessel size, & flow rate drive laminar vs.
turbulent flow.

Answer 27

As flow rate increases their is a critical point at which the flow goes from laminate to turbulent. The higher the viscosity or the narrower the vessel the less flow is needed to reach that point.

Question 28

Describe the branching anatomy of the vascular system (connectivity, size, numbers of
vessels).

Answer 28

Arteries break up into arterioles and then capillaries. Arterioles are the main part of the system responsible for pressure regulation whereas capillaries are responsible for diffusion. Flow rate remains constant because the overall cross-sectional area of the capillaries is extremely high compared to other parts of circulation.

Question 29

Identify the three main components of blood and the process used to separate them.

Answer 29

Red Blood Cells, Plasma, and Serum. These three are separated from one another by being put through a centrifuge with a compound that blocks clotting of plasma.

Question 30

Describe the makeup of the Plasma and Serum Layers.

Answer 30

Plasma and Serum are similar in there chemical make up but differ in that plasma contains fibrinogen whereas serum does not.

Question 31

Describe how renal failure can be obtained via Hematocrit and Erythropoietin.

Answer 31

When Hematocrit is low that indicates a lack of RBCs and therefore require Erythropoietin to produce more RBCs. This means that at low hematocrit high amounts of erythropoietin is released by the kidney.

Question 32

What value is used to measure anemia? How do you get that value?

Answer 32

MCV or Mean Corpuscular Volume is used to measure anemia.
MCV=Hematocrit/Red Blood Cells
Determines how much of the blood is actually made up of RBCs.

Question 33

What values indicate low, normal, and high anemia levels? What do they indicate?

Answer 33

Low MCV = MCV<80 Iron Deficiency or Thalassemia
Normal MCV = MCV 80-100
- Normal MCV can still indicate anemia but is instead based on the concentration of young RBCs, Reticulocytes
- Low Reticulocytes
o Bone Marrow or Renal Disease
- High Reticulocytes
o Acute Blood Loss or Hemolytic Anemia
- Normal Reticulocytes is < 2% of RBCs.
High MCV = MCV>100 B12 or Folate

Question 34

Explain the balance between Coagulation, Anticoagulation, and Fibrinolysis. What happens if one were to go wrong?

Answer 34

Coagulation is responsible for forming blood clots with thrombin. If coagulation did not work bleeding would be unable to stop.
Anticoagulation is responsible for maintaining and controlling the amount of coagulation that takes place. Without anticoagulation coagulation can run rampant and produce a clot.
Fibrinolysis lyses and breaks down clots. Without fibrinolysis a blood clot could break off and become a thrombosis within the blood.

Question 34

Explain the function of the white blood cells.

Answer 34

Neutrophils – Acute response to bleeding and triggers coagulation factors.
Lymphocytes – Immune response
Monocytes – Immune response
Eosinophils – Respond to parasites and are partially involved in allergy responses
Basophil – Cell type that include heparin and histamine

Question 35

Describe platelet adhesion activation and aggregation.

Answer 35

When an endothelial cell is damaged vWF is released and binds onto the Gp1b receptor on the platelet’s membrane. Additionally other molecules are also released by the damaged endothelial cell which can attach to receptors on the platelets. Once attached the platelet releases its alpha and dense granules. Other platelets attach to one another via fibrinogen bridging their GP Fibrilla which also causes new platelets to be activated and further recruit platelets. After the platelet plug is formed coagulation begins.

Question 35

Describe the anatomical make up of a platelet.

Answer 35

A platelet is a chunk of a much larger cell called a Megakaryocyte. Platelets do not have nuclei but instead carry Alpha granules and dense granules. Alpha granules contain fibrinogen and clotting factor 5. Dense granules contain ATP, ADP, Serotonin, and Ca2+ which helps recruit more platelets.

Question 36

What are three screening tests for blood disorders and what can they tell us if something is defective?

Answer 36

Activated Partial Thromboplastin Time measure the intrinsic and common pathway. The intrinsic pathway has three deficiencies that are associated with bleeding XI, IX, and VIII.
To remember this think 8 9/11 H8 9/11 Hate 9/11 for making people bleed.
Prothrombin Time measure the Extrinsic and common pathway. If this time is abnormal than the main cause of the blood disorder is likely factor VII.
Finally, Thrombin time measures the formation of fibrinogen to fibrin and can detect if there is a problem within the common pathway.

Question 37

Describe the mechanisms of anticoagulation.

Answer 37

Protein C, Protein S, and Antithrombin make up most of the anticoagulation mechanism. Protein C binds with APC-EPCR and through a reaction with Protein S inactivates factor V and 8.

Question 38

Describe the mechanisms of fibrinolysis.

Answer 38

Plasminogen becomes plasmin through a reaction with t-PA from endothelial cells and u-PA from plasma. Plasmin is then able to breakdown fibrin.

Question 39

What are the main inhibitors of fibrinolysis and where do they occur?

Answer 39

PAI-1 and PAI-2 inhibit the formation of plasmin from plasminogen. Alpha2-AP inhibits plasmin from breaking down fibrin.

Question 40

What is the key component of cardiac muscle fiber orientation? And their movement?

Answer 40

Cardiac muscle fibers as you move from the outside in change in a clockwise manner. And the movement of these fibers during a contraction are from the outside in counterclockwise to clockwise.
Outer Epicardium Fibers face up and to the left. To remember twisting and untwisting direction just think as though the fibers were stuck at the top and only the bottom half can contract, as you are looking from below.

Question 41

Describe the twisting that takes place during systole, diastole, and how blood is filled or ejected from the ventricle.

Answer 41

During systole the fibers contract in an outward fashion. The inner endocardium contract clockwise (untwisting) and triggers isovolumetric contraction. Afterwards, the epicardium contract in the opposite counterclockwise (twisting) direction and with their higher torque overcome the endocardium untwisting. This triggers ejection from the ventricle as pressure is now high enough to eject blood.
At the start of diastole when systole has finished the fibers stretch back into their original configuration, but the endocardium works like a spring and over stretches before returning in a clockwise manner, this recoiling works to suction up blood at the beginning of isovolumetric relaxation. Finally, diastole finishes with the filling of the ventricle.

Question 42

What is the equation for Cardiac output, Stroke Volume, and Ejection Fraction? What do these values indicate?

Answer 42

Cardiac Output = Heart Rate * Stroke Volume – Measures the amount of blood released during a systolic contraction.
Stroke Volume = End Diastolic Volume - End Systolic Volume – Measures the amount of blood removed from the heart during systole.
Ejection Fraction = End Diastolic Volume – End Systolic Volume / End Diastolic Volume or Stroke Volume / End diastolic Volume – Measures the percentage of blood actually ejected from the heart vs the amount of blood available.

Question 43

Describe Tension Heat and the reason it is used.

Answer 43

When the heart undergoes isovolumetric contraction, no work is technically being done because blood is not moving, however energy is being expended to contract the muscle and the energy is instead transformed into tension heat. A high-tension heat can indicate cardiac hypertrophy which causes decreased blood pressure and more overall energy expenditure from the heart.

Question 44

Explain Cooperative muscle contraction and relaxation

Answer 44

When one myosin head can attach with actin it further moves tropomyosin from nearby sites allowing those sites to bind to actin without the need for calcium. This allows for large portions of myocardium to contract even. A similar process happens with relaxation but in reverse.

Question 45

What are two ways in which myocyte force generation can be increased?

Answer 45

Increasing fiber and sarcomere length, also known a preload.
Increasing inotropy, or the strength of contraction.

Question 45

Why does lengthening myocytes improve their force generation and output?

Answer 45

Longer myocytes are stretched in such a way that the overlap of myosin and actin is increased and the area between them is smaller. This allows for more active sites to be present at any given time. Likewise this causes higher sensitivity to calcium. But cooperative relaxation helps unbind calcium so calcium can keep rebinding more to trigger more contractions.

Question 46

Describe Parasympathetic regulation of cardiac pacemakers.

Answer 46

Binding of acetylcholine to muscarinic receptors causes the G Protein subunits to open GIRK channels and inhibit cAMP production. G Alpha Inhibitor Subunit causes inhibition of cAMP production. G Beta Gamma opens GIRK channels.

Question 46

What is the conduction pathway of the heart?

Answer 46

SA Node -> AV Node -> Bundle of His -> Left and Right Bundles -> Ventricular Muscle -> Purkinje Fibers

Question 47

Which parts of the conduction pathway have slow Aps? Why and what do they do as a result?

Answer 47

The SA and AV nodes both have slow action potentials caused by slower depolarization. These lack a sodium pathway that can quickly depolarize the cell. The SA and AV nodes can set the rate for the heart because they must depolarize first before the rest of the heart.

Question 48

Describe two methods of cardiac pacemaker sympathetic regulation.

Answer 48

Sympathetic stimulation of Beta Receptors increases heart rate by binding cAMP to “Funny” channels and by binding PKA to l type calcium channels.

Question 49

Describe Parasympathetic regulation of cardiac pacemakers.

Answer 49

Binding of acetylcholine to muscarinic receptors causes the G Protein subunits to open GIRK channels and inhibit cAMP production. G Alpha Inhibitor Subunit causes inhibition of cAMP production. G Beta Gamma opens GIRK channels.

Question 50

Describe normal heart values dealing with heart rate and stroke volume.

Answer 50

Heart Rate 60-100
Stroke Volume 30-65 ml

Question 51

Describe the reflex arc

Answer 51

Afferent nerve from sensory limb -> goes to either the brain or the spinal cord -> Finally the effector triggers and change in blood flow is resisted or increased

Question 52

What are the main type of sensors found in blood vessel reflexes?

Answer 52

Peripheral Sensors detect mechanical and chemical signals
Central sensors detect hypoxia

Question 53

Describe the relationship between sympathetic and parasympathetic outflow at any one time.

Answer 53

Parasympathetic and sympathetic outflow remain in a state of balance in which if one is high the other is low and vice versa.

Question 54

Define Systolic and Diastolic Function. How do you measure them?

Answer 54

Systolic function is how well the heart contracts and is measured through ejection fraction.
Diastolic function is a measure of ventricular compliance or how well the ventricle is filled.

Question 55

Define preload, afterload, and contractility.

Answer 55

Preload – Load prior to contraction
Afterload – Force resistant to ventricular contraction
Contractility – Slope on a PV loop that shows ventricular function.

Question 56

What happens to LV pressure if its compliance decreases?

Answer 56

The left ventricle will have a much higher pressure on its walls for less volume.

Question 57

What are the different types of cardiac intrinsic circulation?

Answer 57

Autoregulation – Maintains flow so that it can be relatively constant
Myogenic Regulation – Invoked for sudden changes in pressure
Endothelial Mediated Regulation – Release of nitric oxide
Metabolic Regulation – combination of metabolic vasodilators and vasoconstrictors

Question 58

Explain why the heart requires a large amount of oxygen and explain the mechanism it uses to meet its demands.

Answer 58

The heart is always on and constantly pumping blood during periods of high intensity these oxygen demands can increase. The heart is one of the last organs to get oxygenated blood so the only way it can meet high oxygen demands is to increase blood flow drastically.

Question 59

What is coronary autoregulation?

Answer 59

The main component of coronary autoregulation is the balance between resistance and pressure to maintain flow.
Flow = Pressure/Resistance so if one value increases the other one must compensate.

Question 60

Explain coronary blood flow during systole and diastole.

Answer 60

During systole there is almost no blood flow because the contraction of the heart muscles closes the vessels and can even cause back flow. However, during diastole blood can flow.

Question 61

Explain vasodilators and vasoconstrictors of the heart.

Answer 61

During periods of high intensity, the heart must increase its cardiac output, usually by increasing heart rate, so that blood flow can increase to deliver oxygen and remove CO2. However, the vascular smooth muscle of the heart will likewise vasodilate to accommodate its needs.

Question 62

Explain how blood can be shunted towards muscles that need more oxygen.

Answer 62

Muscles that are currently being used during exercise produce large amounts of indicators of metabolic activity and vasodilate as a result. Other skeletal muscle however vasoconstricts as blood in not needed to all the muscle.

Question 63

Explain the Venous Muscle Pump.

Answer 63

The veins have a system that can prevent backflow but not necessarily enough force to move blood on its own. However, by activating skeletal muscle the vein can be squished and push blood. When skeletal muscle relaxes the veins pull up blood.

Question 64

Explain Lymph and its starling forces.

Answer 64

Lymph is a way to retain water and recycle molecules that are not used and reintroduce them into circulation. Lymph flow is directly correlated with interstitial pressure so if the starling forces favor the interstitial fluid lymph flow will increase.

Question 65

What organs are involved in splanchnic circulation?

Answer 65

Liver, Stomach, Spleen, Pancreas, Small Intestine, and Colon.

Question 66

What is a unique thing about the splanchnic circulation?

Answer 66

It has a anticipatory CNS response

Question 67

What is a blood reservoir?

Answer 67

The Spleen, Liver, and Abdominal veins are capable of housing many red blood cells and as a result in times of need can release the blood cells.

Question 68

Breakdown the livers oxygen needs and the vessels it uses to obtain them.

Answer 68

25% of resting cardiac output is used by the liver.
- 25% of which is from the hepatic artery
o Supplies 75% of its oxygen needs
- 75% of which is supplied by the portal vein
o From the kidney
o Supplies 25% of its oxygen needs

Question 69

Name the two different types of skin and their properties.

Answer 69

Apical Skin which vasoconstricts in response to sympathetic activity
Nonapical skin is vasodilated by bradykinin

Question 70

What is orthostasis?

Answer 70

It is how the body reacts to standing up and the hydrostatic pressure change it causes. The hydrostatic pressure change causes a reduction in venous return.

Question 71

How does orthostasis work?

Answer 71

Standing up decreases venous return -> decreases stroke volume -> decreased cardiac output -> decreased MAP -> deactivates baroreceptor -> increases sympathetic to the heart and blood vessels -> increased heart rate and contractility -> MAP returns to normal
Basically almost every blood pressure parameter decreases and is raised back to normal as a response

Question 72

What is a vasovagal syncope?

Answer 72

A response to acute emotional distress in which sympathetic are withdrawn and parasympathetics are activated.

Question 73

What is the result of a vasovagal syncope?

Answer 73

Decreased sympathetic and increased parasympathetics causes a drop in MAP -> decreases blood flow to the brain -> loss of consciousness.

Question 74

Why is passing out the brain’s response?

Answer 74

By balancing the hydrostatic pressure by fainting, the brain can get blood back.

Question 75

What fixes vasovagal syncope?

Answer 75

Deactivated baroreceptors caused by the decrease of MAP triggers sympathetic outflow and inhibits parasympathetic outflow.

Question 76

Explain the sympathetic response in a fight or flight situation.

Answer 76

Stress triggers a response within the CNS. Sympathetic nervous system and endocrine systems are activated. Sympathetic outflow is increased beyond that of normal exercise. Endocrine changes involve increased antidiuretic hormone ADH and vasopressin release which causes vasoconstriction and water retention.
Sympathetic vasopressin vasoconstriction increases preload but vasodilates pulmonary vessels to allow more perfusion of oxygen systemically.

Question 77

Compare and contrast the pre/early exercise response and the late response.

Answer 77

Pre/early
- Increased sympathetic outflow to increase cardiac output.
- Active muscles vasodilate via beta-2 receptors to allow for more blood and vasoconstriction occurs in the non-active muscles.
- Vasoconstriction occurs in apical skin.
Late
- Desensitization of baroreflexes.
- Muscles sustain sympathetic effects.
- Metabolites and histamines promote vasodilation
- Venous return increases
- Epinephrine vasodilates skeletal muscle and increases cardiac output
- Sweat is released from non-apical skin by vasodilation

Question 78

What is hemorrhage?

Answer 78

Blood loss

Question 79

What is reversible hemorrhage vs. irreversible hemorrhage?

Answer 79

Reversible hemorrhage is 10-20% of blood volume lost.
- Can be compensated by bodily functions.
Irreversible hemorrhage is >30 % blood volume lost.
- Cardiovascular system cannot compensate
- Results in hemorrhagic shock

Question 80

How is reversible hemorrhage reversed?

Answer 80

Large sympathetic response.

Question 81

What is epinephrine’s effect on the cardiovascular system?

Answer 81

Cardiac Beta 1 Increases Heart Rate and Contractility
Systemic Vessels Beta 2 Vasoconstriction
Muscle Vessels Beta 2 Vasodilation

Question 82

What is Angiotensin II’s effects on the cardiovascular system?

Answer 82

Decreased blood flow activates the RAAS system which uses renin to activate ANG into ANG II within the kidneys. ANG II causes vasoconstriction, neuronal NE release, increased aldosterone release, and cardiac and vascular hypertrophy if chronically on.