Systemic venous blood pressure is aka?
Central venous pressure.
What is the resistance like in the venous compartment?
it is very small.
What is pulse pressure like in the capillaries?
No pulse pressure.
What is arteriosclerosis?
hardening of arteries that leads to a loss of normal elastic dampening, and this leads to passing on the pulse of the waves downstream where it can do damage.
What is the average pressure in veins?
zero mm Hg
Systemic venous blood pressure is aka?
Central venous pressure.
What is the average central venous blood pressure?
zero mm Hg
What makes the central venous blood pressure rise above zero?
The collective venous pump system.
What makes up the venous pump?
Valves and skeletal muscle.
What are the 2 pumps in the systemic circulatory system?
1. The left ventricle. 2. The collective venous pump.
What is hydrostatic forces?
the affect of gravity on blood pressure.
With hydrostatic forces what part or level of the body while standing will blood pressure be at 100 mm Hg?
At the level of the heart.
When standing what will the venous blood pressure in the feet rise to?
about 90 mm Hg
When walking what will the venous blood pressure in the feet rise to?
about 25 mm Hg.
What is venous pressure like in the head while standing?
negative (well not actually negative, but air can enter here with an accident because there is no pressure).
How was blood pressure taken in the old world?
By palpating for a pulse and then looking at tissues.
What is the modern world name used for how we meausre blood pressure?
What is a formula for blood pressure?
cardiac output multiplied by peripheral resistance.
What are 3 causes of peripheral resistance?
1. Blood volume. 2. viscosity of blood. 3. size of vasculature container (r^4).
What can affect blood pressure?
What do we need to do to determine the anti-hypertensive therapies we can use?
Determine what is causing the hypertension.
What is mean arterial blood pressure?
it is cardiac output multiplied by peripheral resistance usually 100mm Hg.
Since we said delta-P is stable we took it out of the equation for flow, but what makes delta-P stable or constant?
a dozen or more control systems.
What would a control that is high gain and low gain mean?
High gain would be high power to correct something. Low gain would be low power to correct something.
What are the 2 main controls of blood pressure?
1. Baroreceptors. 2. Renal-blood pressure control.
Short term and long term blood pressure controls are best done with what system?
Short term- ANS affecting the heart and vessels. Long term- controlling blood in vascular compartments.
What receptors will function as a baroreceptor for controlling blood pressure? Where are they found at?
aortic and carotid baroreceptors. Aortic found on aortic arch. Carotid found in carotid bifurcation
What type of sensors are baroreceptors?
What cranial nerves make up these baroreceptors that help control blood pressure?
aortic- X, Carotid-IX.
Where are signals from the baroreceptors sent?
To the cardiovascular center in the brain medulla.
How will baroreceptor reflex alter blood pressure?
Through efferent innervation to heart and vasculature.
If blood pressure is low how will the baroreceptor reflex help?
The receptors send signals to the brain and then the brain will send an increased sympathetic respons to the heart and increase cardiac output. It will send an increased sypmathetic respons to blood vessels to vasoconstrict.
If blood pressure is high how will the baroreceptor reflex help?
The receptors send signals to the brain and then the brain will lessen the sympathetic respons to the heart and decrease cardiac output. It will lessen the sypmathetic respons to blood vessels and will slow vasoconstriction.
How sensitive are baroreceptors?
very responsive at normal blood pressures.
How fast acting, and effective are baroreceptors at stabalizing blood pressure?
Rapid-acting and high gain.
How long will baroreceptor reflex work at stabalizing blood pressure?
about 2-4 days and then it falls off.
After 2-4 days when barorecpetors stop working what are they doing?
They are re-adjusting the level at which they will help correct blood pressure levels.
What is the suggested usage for the baroreceptor refelx?
For sudden changes in Blood pressure.
What is the baroreceptor reflex used for?
What will the mean blood pressure be if the baroreceptor refelx is gone?
It will remain at 100 mm Hg, but it will vary a lot more.
What will the arterial chemoreceptor reflex use?
Chemical sensors for oxygen.
Where are the chemoreceptors found at?
They are extremely well supplied with blood in small organs called Aortic and carotid bodies.
how fast and how effective is the chemoreceptor reflex at regulating blood pressure?
Rapid-acting and high gain.
How long will the chemoreceptor reflex last for?
Only a couple hours.
What will these chemoreceptors monitor?
Really low levels of Oxygen and high levels of Co2 and H+ .
When will the chemoreceptor reflex be used?
When mean arterial blood pressure drops below 80 mm Hg.
What will the chemoreceptor reflex help control?
What is atrial stretch reflex?
a nervous system control that uses stretch receptors in the walls of the atria to regulate blood pressure.
What are the receptors called used in atrial stretch reflex?
Atrail stretch receptors.
Which atrium is most notable for the atrial stretch reflex and why?
right atrium because right atrial pressure is so low.
The atrail stretch reflex receptors really monitor what?
How fast and efficient is the atrial stretch reflex at regulating blood pressure?
Rapid acting and the gain is unknown.
What type of effect will atrial stretch reflex have?
can cause an additional 50% increase in heart rate.
The atrial stretch reflex is known as what?
When atrial stretch reflex increases heart rate this will increase cardiac output which stimulates arterial baroreceptors and this creats competition between these 2 reflexes when will each of them dominate?
Bainbridge reflex- dominated when blood volume rises. Baroreceptors dominate when blood volume diminishes.
What is the purpose of the bainbridge reflex aka the atrial stretch reflex?
to minimize venous damming of blood.
What is the hormonal effect that comes from atrial stretch reflex?
atrial myocytes will release atrial natriuretic factor (ANF) when the atrial pressure/stretch occurs.
What will atrial natriuretic factor do?
The effect is seen on the kidneys and it will decrease the blood volume and decrease blood pressure.
What causes the CNS ischemic response to blood pressure?
a cerebral ischemia.
When we have a cerebral ischemia what will the cns ischemic response do?
Neurons in the cardiovascular control center become hyperactive.
What are the neurons in the cardiovacular center that become hyperactive?
Neurons of the medullary pressor area.
How fast and how effective is the CNS ischemic response?
Very fast and high gain.
How long will CNS ischemic response work for and why?
only a hour or so because the brain realisitcally cant be in ischemia for longer than this.
Why will a cerebral ischemia cause the hyperactive neurons?
It is due to very slow moving blood failing to remove the CO2 from the cardiovascular center.
When will the CNS ischemic response be seen?
In rare situations that involve life threatening hemorrhage it is like a last ditch attempt to increase blood pressure in emergency.
Where is the cardiovascular center found at?
ill defined neuronal groups found in the lower 1/3 of pons and the medulla.
What are the 2 regions of the cardiovascular center?
1. Pressor region. 2. Depressor region.
What will the pressor region of the cardiovascular center do?
evokes vasoconstriction, cardiac acceleration, myocardial contractility. This is also responsible for vasomotor tone.
What will the depressor region of the cardiovascular center do?
Evokes inhibition of the Pressor area: So it will decrease sympathetic outflow and increase parasymphathetic activity. This leads to vasodilation.
Mental states can influence blood pressure by how?
Through cardiovascular center.
What will depression and fright/shock do to blood pressure?
What will excitement anxiety and mild pain do to blood pressure?
How will the Epinephrine system help regulate blood pressure?
It sends hormones through the humeral control system from adrenal medulla.
How will the hormones from the Epinephrine system act?
As sympathetic neurotransmitters.
What are the 2 hormones released by the Epinephrine system?
1. Epinephrine (80%). 2. Norepinephrine (20%).
what will the hormones released by the epinephrine system land on and what will this do?
They land on alpha and beta receptors and cause peripheral vasoconstriction and increase cardiac output.
How fast and how effective is the epineprine system at regulating blood pressure?
Very fast and gain is unknown.
How long will the epinephrine system help regulate blood pressure?
rather long lasting.
What is the stress-relaxation behavior that helps regulate blood pressure?
a property of the arterial system that after increased or decreased constant pressure will result in a new contractile state. A re-sizing of the vascular compartment.
How fast and effective is the stress-relaxation behavior at regulating blood pressure?
Slow with a low gain.
What is the capillary fluid shift that helps regulate blood pressure?
a redistribution of blood to and from the vascular compartment (sending blood out to tissues or bringing it back in).
How fast and how effective is the capillary fluid shift at regulating blood pressure?
slow and has a low gain.
Capillary fluid shift can cause what type of pathology?
What will the renin-angiotensin system use to regulate blood pressure?
the humoral control system by sending hormones from the kidneys and blood.
What hormones will the renin-angiotensin system use?
renin and angiotenin II.
How fast and how effective is the Renin-angiotensin system at regulating blood pressure?
slow acting and has a low gain.
The renin-angiotensin system will increase and decrease blood pressure where?
at afferent arterioles.
The renin-angiotensin system will increase and decrease sympathetic stimulation to what?
What will renin do?
Convert angiotensinogen into angiotensin I
Angiotensin I will be converted to angiotensin II by an enzyme and what will angiotensin II do?
Increase vasoconstriction of peripheral vasculature. It also increases aldosterone which increases NA2+ and h2o absorption which increaes blood volume.
What happens to renin production if blood pressure is increased?
It will slow down and then it wont convert angiotensinogen into angiotensisn II.
What is an ACE inhibitor?
a drug that blocks angiotensin converting enzyme (ACE) so no angiotensin II can be made and this will help keep blood pressure from rising due to renin.
What is the aldosternoe system for regulating blood pressure?
aldosterone is released from the adrenal cortex.
What will alodsterone do?
It works closely with the renin-angiotensin system. It increases and decreases angiotensin II levels which increases and decreases K+ levels
How fast and effective is the aldosterone system at regulating blood pressure?
slow and low gain.
How will the vasopressin system regulate blood pressure?
it uses osmoticaly sensitive neurons in hypothalamus to make a hormone that is released from the posterior pituitary gland called vasopressin.
What is another name for vasopressin?
anti-diuretic hormone (ADH)
Why will vasopressin have 2 names?
Because it has 2 functions.
What are the 2 functions of vasopressin aka anti-diuretic hormone.
1. cardiovascular pressor agent. 2. renal fluid retention agent.
Vasopressin will cause vasoconstriction on smooth muscles with what receptors?
How fast and how effective is vasopressin system at regulating blood pressure?
slow and gain is unknown.
The renal-blood fluid system for regulating blood pressure uses what?
What part of the kidneys and what other system is involved with the renal-blood fluid system?
the nephron and the renin-angiotensin system.
How fast and effective is the renal-blood fluid system at regulating blood pressure?
slow but a VERY high gain Some say it is infinite because it removes fluid from body.
The renal-blood fluid system is the _______ mechanism.
Renal -blood fluid system relies on a phenomenon known as what?
What is Diuresis?
Formation of Urine.
What is pressure diuresis?
increase arterial blood pressure and increase water disposal.
What is pressure natriuresis?
increase arterial blood pressure and increase salt disposal.
The renal-blood fluid mechanism is due to what?
Explain how drinking water increases urine?
increase extracellular fluid increase blood volume, this increases mean systemic blood pressure, and this increases venous return, and this increases cardiac output, This increases arterial BP and this increases pressure diuresis.
What is harder to do pressure diuresis or pressure natriutesis?
Pressure natriuresis. Excreting salt is harder that water.
What are 2 long term determinants of long-term arterial pressure?
1. Level of water and salt intake. 2. Behavior of kidneys.
What are factors in kidney behavior that effects the renal-blood fluid system?
addition of hormonal controls and abnormal nephrons.
What will the chronic renal output curve look like?
it is a very very sharp curve that shows salt intake or output is directly related to extracellular fluid volume.
What will angiotensin do to the kidneys?
Makes them retain salt and water.
What will angiotensisn do to the adrenal glands?
increase aldosterone secretion which increases salt and water retention in the kidneys.
What is hypertension (#'s)?
Systemic blood pressure greater than or equal to 140 and/or diastolic blood pressure that is less than or equal to 90.
What is primary and secondary hypertension?
Primary- origins of hypertension are unknown. Secondary- origins of hypertension are known.
What is a diuretic?
A drug that makes the kidneys make more urine.
Short term systems that regulate blood pressure do what?
Alter the cardiac output and alter the peripheral resistance.
Long term systems that regulate blood pressure do what?
Alter the volume of blood in the vascular compartment.
What type of disorder is renal artery stenosis?
a vascular stenosis to the kidneys.
What is renal artery stenosis usually due to?
Renal artery stenosis is a secondary hypertension called what?
Renal vascular hypertension.
What are the symptoms of intermittent claudication?
Intermittent pain in the lower extremities during exercise.
Intermittent claudication is associated with what?
Poor diet, lack of exercise and smoking.
Blood circulation through the body is due to what 3 factors?
1. nature of blood flow. 2. blood flow determinants. 3. The heart.
What organs receive over 1 liter of blood per minute?
Kidneys, and GI tract.
What happens to blood flow in the left coronary artery with ventricle systole and diastole?
Systole- decreases flow as the ventricle contracts. Diastole- increases flow as the ventricle relaxes.
What are 2 controls of flow thorugh the coronary arteries?
1. vasodilation of sympathetic fibers. 2. local metabolic factors from cardiac myocytes cause vasodilation.
What causes cardiac muscle to vasodilate with a sympathetic stimuli?
Beta 2 receptors.
What causes the cardiac muscles to vasodilate from metabolic factors?
release of CO2 and H+, and adensoine.
What are the consequences of an obstruction in the coronary artery?
What is the term used for a chest pain from myocardial ischemia?
Is angina pectoris a heart attack?
no it seldomly involves permanent damage.
What is Coronary artery disease caused by?
atherosclerosis which comes from high fat diets, genetic predispositions and lack of exercise.
What is the test used to evaluate the degree of a coronary artery inclusion?
Besides having restricted flow with coronary artery disease what else happens?
Often have a damaged epithelial lining.
What happens to arteries when they have damaged epithelial lining?
They lack the normal responsiveness to vasoactive agents and tend to spasm. Also the clotting system is promted.
What is the term used for death of cardiac muscle tissues?
Myocardial ischemia can progress to what?
What will determine how much the cardiac output is damaged with a myocardial infarction?
The amount of myocardial death.
A heart attack is aka?
coronary, or myocaridal infarction.
What happens to blood in coronary arteries with a heart attack and why?
it declines because the cardiac output is low.
What happens to myocardium around the site of infarction?
We get hyper-excitable patches of myocardium that can become the pacemaker and cause fibrillation.
What is a cardiac tamponade?
A rupture of the infarction due to thinning and systolic stretch.
How effective can CPR performed right be at maintaining cardiac output?
30% which is good enough until defibrillation can be done.
Healing from a heart attack can happen when?
There is a development of collateral microvasculature and hypertrophy of surrounding myocardium.
How much blood goes to skeletal muscles at rest and how much during strenuous exercise?
Rest- 4 ml/min/100g. Active- can be as high as 80 ml/min./100g.
How is flow to skeletal muscles changed during contraction and relaxation?
Contraction- flow goes down because of compression. Relaxation- flow increases.
What ways will blood flow be controlled to skeletal muscles?
1. sympathetic fiber innervation. 2. Local metabolic factors.
Of the controls of blood flow to skeletal muscles which one is the greatest factor?
Local metabolic factors.
Will sympathetic fibers to skeletal muscles cause vasoconstriction or vasodilation for blood vessels?
How can sympathetic fibers going to vasculature of skeletal muscle cause both vasoconstriction and vasodiliation?
It depends on the receptors if the vessels have Alpha-1 receptors then they will vasoconstrict, but if they have beta-2 adrenergic receptors they will vasodilate.
How will local metabolic factors control flow of blood to an area?
They will cause a vasodilation when the area produces CO2 and H+ so more blood can come there and remove the metabolic waste.
what will mass sympathetic discharge do?
Increase cardiac output and wide-spread vasoconstriction which leads to better delivery of blood.
What area of the body is given the highest priority for blood?
The cerebral circulation.
What is blood flow like in the brain?
It is constant at 700 ml/min.
Can the brain hold more blood?
No there is no room.
What part of the body is least tolerant to ischemia?
What happens when there is a cerebral blood vessel blockage?
Cerebral stroke aka cerebrovascular accident.
What will often precede a cerebral stroke?
Transient ischemic attack.
How is blood flow controled to the brain?
Just one way through local metabolic factors from neurons.
CSF is turned over how much every day? How much csf is there at a given time?
500 ml/day and there are only 150ml at a time.
What is the difference between csf and normal plasma?
csf has increased na2+, and decreased glucose and K+
What part of the body is given the lowest priority for blood?
The splanchnic circulation.
Blood flows from Stomach and small intestines to where through what?
To the liver through the portal system.
How is blood flow controled to the GI tract?
1. Local metabolic factors. 2. Nervous innervation by sympathetic fibers.
What control system of blood flow for the GI tract is the most powerful?
The local metabolic factors are powerful, but they can be profoundly overridden by sympathetic innervation.
What will sympathetic innervation to the GI tract do?
What will parasympathetic innervation to the GI tract do?
It will cause glandular activity that will cause vasodilation.
What is another name for a ischemia to the GI tract?
Excess fluid can accumulate in the peritoneal compartment in a condition known as what?
Where will blood that comes to the liver come from?
25% from the hepatic artery, and 75% from the hepatic portal vein.
How is blood flow controlled to the liver?
By local intestinal factors.
What can the spleen do?
It can store up to about 50 ml of concentrated RBCs.
What will cause the spleen to release the storage of RBCs?
Strong sympathetic stimulation.
What is the normal role of the spleen?
To cleanse blood of old blood cells.
How much blood flows to the kidneys?
How is blood flow controlled to the kidneys?
It is rather steady, but sympathetic innervation produces vasoconstriction and a drop in flow.
How much of blood flow can go to the skin?
0-30 % of cardiac output.
What happens to blood flow to the skin when core temperature is high?
Vasodilation and sweating.
What happens to blood flow to the skin when core temperature is low?
Vasoconstriction and no sweating.
How is blood flow to the skin controlled?
just nervous innervation by sympathetic fibers.
Why is blood flow to the skin not dependant on local metabolic factors?
integument gets about 10 times more flow than it would generally need to remove local metabolic factors.
What will sympathetic innervation to arteries in the skin cause?
Vasodilation and vasoconstriction.
Cold temperatures will also release what and from where?
epinephrine release from adrenal gland.
What will innervate sweat glands?
Cholinergic sympathetic fibers.
What happens to smooth muscle that is vasoconstricting arteries in the skin when they get too cold?
They get paralysis and stop vasoconstricting and this results in a vasodilation and this will send lots of blood to the cold area and warm it up, but can lower core body temperature very fast.
What is the term used for the condition when smooth muscle stops vasoconstricting arteries of the skin and core body temperature can go down fast?
What is the term used for when tissue freezes and dies?
What is intermittent claudication due to?
Atherosclerosis affecting arteries of the legs.
What causes pain in intermittent claudication?
it is an ischemic pain due to loss of circulation and drainage.
Why willl intermittent claudication only hurt people when they are walking?
That is when they need more blood that they cant get because of the atherosclerosis.
Circulatory shock is a life-threatening condition due to what?
Widespread, inadeuate blood flow.
What happens to blood pressure with circulatory shock?
It can increase or decrease.
What happens to metabolism with circulatory shock?
What happens to muscle strength and mental function with circulatory shock?
They both decrease.
The blood pressure in the system is created primarily from what?
What determines cardiac output?
Cardiac output =?
What determines vascular resistance of the body?
The size of peripheral vascular tubes which is a collective r4.
So if delta-P (pressure difference) is set by cardiac output and cardiac output is set by venous return then what collective behavior will determine cardiac output?
Behavior of vascular tubes. Or the collective r4.
What will determine the r4 for the entire system?
Local factors from metabolizing tissues.
So after all of that what will determine the cardiac output?
The heart is a permissive pump that responds to what?
How will increasing metabolism increase cardiac output?
it will increase local metabolites which increase vasodilation and increase flow into the venous system which increases venous return which increase cardiac output.
What are the 2 outputs in the cardiovascular system?
1. cardiac output. 2. tissue output (coupled with venous pump)
What are the 2 pumps for the systemic circulation of blood?
1. Left ventricle. 2. Collective skeletal muscles.
If r4 for a given area increases what happens to Q?
It should increase.
What keeps blood pressure from dropping off all the way when r4 increases and so flow increases?
Delta-P must be maintained.
Blood pressure in the short-term is regulated how?
Regulated by the redistribution of blood.
How is mean systemic filling pressure made?
average of all arterial and venous pressures.
What is the mean systemic filling pressure usually at?
10 mm Hg.
Why is the mean systemic filling pressure so low?
Because most blood is in the venous system and this is very low pressure.
What system can control the potential chaos that could result from excessive demands of tissues all crying out I want blood?
The sympathetic nervous system can modify the cardiac output and peripheral tissues.
Why do we need to warm down after exercising?
it is needed to prevent sudden post-exercise pooling of blood through venous pumping.
what is VO2?
the volume of o2 consumed per minute.
What is a typical VO2 at rest?
What is maxvo2?
Maximum aerobic limit.
What is A-V O2?
Arteriovenous oxygen difference. It is a measure of tissue metabolism.
With exercise Q or flow of blood is sent where?
To brain as a constant and sent to skin for sweating, also muscles and heart.
With exercise Q or Flow of blood is decrease where?
Mean arterial pressure divided by Resistance equals what?
What is the source of flow for pulmonary circulation?
What shape will the right ventricle be?
Crescentic or "c" shaped.
How much blood will the right ventricle pump compared to the left ventricle?
The same amount per unit time. Just not as far.
What is the normal or average pulmonary circulation blood pressure?
What is the pulse pressure for the pulmonary circulation?
14 mm Hg.
What is the mean blood pressure for pulmonary system?
13 mm Hg.
What will the blood pressure be in the capillaries of the pulmonary system?
around 7 mm Hg.
Why can pulmonary blood pressure be so low?
It doesn't need to be high since it only travels short distances from the heart, and the lungs have a negative interpleural pressure.
What will low blood pressure do for the alveoli?
Allows them to remain relatively dry.
How is blood distributed in lungs normally?
The lower 1/3 will have the most blood due to gravity and this area will be over-perfused, The upper 1/3 will not have much blood and it will be under-perfused, and the middle 1/3 of the lungs will be just right.
Pulmonary vasculature is compliant, but what is the size of the container here?
It is small.
Pulmonary blood vessels are like what?
How much blood can be in the pulmonary circuit at any time?
around 450 ml.
How much blood can be in the pulmonary capillaries at any given time?
only around 75 ml.
What is pulmonary edema?
A condition where the lungs accumulate too much blood.
What happens when there is too much blood in the lungs?
It ends up in plasma filtrate and goes into alveoli.
What happens to alveoli when they get blood on them?
This will greatly compromise the ventilation and gas exchange.
Is it possible to shift blood volume between the pulmonary and systemic systems?
What medical condition is associated with blood volume leaving the systemic system and entering the pulmonary system?
Congestive heart failure.
What controls the flow of blood through the pulmonary system?
The venous return. This can be metabolizing tissues in the systemic system.
Why will local factors not regulate blood flow through the pulmonary system?
decreased O2 in the pulmonary system will cause vasoconstriction.
Why will decreased O2 in the pulmonary system cause vasoconstriction?
So the blood can flow to better oxygenated areas.
Will nervous innervation go to the pulmonary system and will it help control flow of blood?
Yes it is innervated, but it will not help regulate flow.
What is circulatory shock?
inadequate blood flow to the extent the tissues become damaged.
What are the 3 basic types of circulatory shock?
1. Hypovolemic shock. 2. low-resistance shock. 3. Cardiogenic shock.
What causes hypovolemic shock?
A hemorrhage (internal or external) that decreased blood volume. Or burns that remove lots of fluids.
Hypovolemic shock is aka?
What causes low-resistance shock?
Due to loss of vasomotor tone.
Low-resistance shock is aka?
What is anaphylaxis?
Widespread mast cell degranulation.
What type of shock is created from anaphylaxis?
What causes a cardiogenic shock?
Loss of pumping capacity.
Cardiogenic shock happens in what percentage of MI patients?
10% and is very deadly.
The warm or cold aspects relate to what?
The presence or lack of compensatory mechanisms at work.
What type of shock will blood pressure increase?
What type of shock will blood pressure decrease?
Why would you lay a patient down with head below trunk to treat shock?
to increase venous return.
What type of disorder is lymphedema?
A tissue swelling disorder.
Ultimately the only blood flow that matters is where?
In the tissues.
What is interstitium?
aka Extra cellular matrix or ECM.
Fluid/molecular movement is a function of what 5 basic factors?
1. Solubility 2. Size 3. capillary permeability 4. concentration 5. pressure.
What are the different types of capillaries?
type I, Type II, Type III.
Of the different types of capillaries which one is most common?
Of the 5 basic factors of fluid/molecular movement which one is a huge determinate of the net flux across an endothelium?
If a molecule can move across a capillary what will primarily drive the permeation ?
pressure dynamics between blood and interstitium.
What are the 4 forces that determine net fluid exchange between the blood and the interstitium?
1. Capillary pressure 2. interstitial free fluid pressure 3. plasma colloidal osmotic pressure 4. interstitial fluid colloidal osmotic pressure.
What is capillary pressure?
An outward pushing force= Pc
What is interstitial free fluid pressure?
an inward pushing force= Pt
What is plasma colloidal osmotic pressure?
an inward pulling force= pi c
What is interstitial fluid colloidal osmotic pressure?
an outward pulling force= pi t
What do these 4 forces (that determine net fluid exchange between the blood and the interstitium) collectively produce?
A net driving force.
What are the actual forces of capillary pressure?
What is the interstitial free fluid pressure?
around -6 mmHg
What is a negative pressure?
It is just below atmospheric pressure.
What is the plasma colloidal osmotic pressure?
around 28 mmHg
What is the interstitial fluid colloidal osmotic pressure?
Around 5 mm Hg
How can we determine the net driving force?
Add up all the pressures.
Of the 4 forces which is the only one that has an inward pressure?
Plasma colloidal osmotic pressure.
What will increased venous pressure do to capillary pressure?
What will increased capillary pressure do to arteriolar resistance?
What will decreased arteriolar resistance do to capillary pressure?
Of the different forces on blood in the capillaries which one is variable?
Pc aka capillary pressure.
What will the net driving force be at for different parts of the capillary?
A net Out of around 7 at the arteriole end and a net in around -7 at the venule end.
What is the net filtration when the net driving force is greater than 0, and when it is less than 0?
Greater than 0 = out, less than 0= in
What is it called when the net fluid loss and net fluid resorption is 0?
Where is the starling equilibrium found at?
Roughly the midpoint of the capillary.
What is the net filtration pressure in the typical systemic capillary?
There is a slight net outward filtration pressure.
Will blood that leaves one capillary return only to the same capillary?
no it can go to other capillaries.
What is the slight net capillary out and what will it cause?
around 0.3 mmHg and it causes a flux from plasma to interstitium.
Since our capillaries lose more plasma than they resorb how much plasma is lost from the capillary system per minute?
What is flux?
A net fluid movement.
A net flux can be more precisely determined by including what 2 factors?
1. Kf= filtration coefficient 2. A= surface area.
What will pick up the lost plasma from the capillary system?
The lymphatic system.
Where are lymphatic capillaries found at?
Nearly everywhere in the body.
What is the pressure like in lymphatic vessels?
Since lymphatic pressure is so low how will it flow?
It uses valves and action of skeletal muscle to move blood.
What is the use of valves and skeletal muscle to move lymph called?
The lymphatic pump.
What can increase the lymphatic fluid pressure?
If the interstitial free fluid pressure is increased.
What is the usual cause of increased interstitial free fluid pressure?
Increased capillary pressure.
Increased capillary pressure will do what to arteriolar resistance and venous resistance?
Arteriolar resistance will decrease, and venous resistance will increase
Of the 4 forces that determine net fluid exchange between the blood and the interstitium which one will go down if the interstitial free fluid pressure increases?
Plasma colloidal osmotic pressure.
What is interstitial free fluid pressure normally like?
It is stable due to natural turgor of tissues that tend to resist internal stretching.
How compliant are tissues generally?
Not very compliant.
What happens to most fluid that leaves the capillaries?
It is conducted into the lymphatic system.
What is the average amount of total body interstitium?
12 liters in average adult.
What is the normal pressure of the lymphatic system?
around -6 mmHg
At what lymphatic pressure will fluid go into the lymphatic system?
anywhere below zero.
What is the safety factor?
The large range for lymphatic pressure where fluid will still be taken in. Lymphatics take fluid in for a decent range on either side of -6 mm Hg.
What is the safety factor analogous to?
Blowing up a balloon it is hard to do until you reach a point and then it is easy to do.
What happens when the safety factor is exceeded?
Fluids pour into tissues.
What is edema?
fluid accumulation in tissues.
How is increased capillary permeability caused?
burns, histamine from mast cells, injury. This allows for increased seepage by way of vessel wall changes.
What can cause a high capillary pressure?
Venous obstruction, acute arteriolar dilation, cardiac failure
What happens with high capillary pressure?
it allows for increased Net driving force and the starling equilibrium shifts to the right.
What can cause a decrease in plasma proteins?
nephrosis (kidney disease), starvation, burns.
What will decreased plasma proteins cause?
It allows for increased seepage due to decreased colloidal osmotic pressure.
What causes lymphatic obstruction?
parasites, or surgery
What will a lymphatic obstruction cause?
Lymphedema because it blocks the drainage from the lymphatic system and increases the interstitial free fluid.
What is lymphedema due to?
accumulation of lymphatic fluid in interstitium.
What will lymphedema cause?
Swelling in tissues.
What is the pressure called that drives fluid out of the capillaries?
What is the fluid that pushes fluid out of the interstitial space called?
Interstitial free fluid pressure.
What is the pressure that pulls fluid in from the interstitial area into the capillaries?
Plasma colloidal osmotic pressure.
What is the pressure that pulls fluid out of the capillaries into the interstitial area?
Interstitial fluid colloidal osmotic pressure.