dynamics of blood circulation

in the laminar flow blood tends to flow in a?

streamlined fashion → straight

in the laminar flow, why is the center layer moving faster than the outermost layer?

center layer → experience less resistant to blood flow

outermost layer → closer to the vessel wall = more resistant to blood

what is turbulent flow?

when its interrupted and blood passes a constriction, sharp turn and rough surface

vibration of blood vessel wall during a turbulent flow makes a ___1____ that you can measure while measuring ____2_____

1. sound

2. blood pressure

what is blood pressure?

• measure of force exerted by blood against the wall

• refers to the arterial pressure

capillary blood flow is __1___ to ___2____ which is closely regulated by a combination of neuro hormonal mechanisms

1. directly proportional

2. arterial BP

how much you have in capillaries depends on?

blood pressure

blood moves through vessels because of

blood pressure

blood pressure is measured by listening for

Korotkoff sounds produced by turbulent flow

what is the sound thats first heard in blood pressure measurement?

• systolic

• caused by turbulence flow

• brachial artery partially open

when sound disappears in blood pressure measurement, what does this indicate?

• diastolic pressure

• laminar flow

• no turbulence

• open brachial artery

what is blood flow?

• the volume of blood moving through a vessel in a given time period

• directly proportional to pressure differences, inversely proportional to resistance

  • increase in pressure difference = increase flow

  • increase resistance = decrease flow

what is the formula to flow?

flow = P1-P2/R

to have flow, what should the value of P1 and P2 be

P1 has to be higher

P2 has to be lower

what does poiseuilles law indicate?

• flow decreases when resistance increases

  • increase in viscosity = decrease flow

  • radius is x^4 → flow would be x^16

• resistance is directly proportional to the viscosity

  • increase in viscosity = increase of resistance and increase in length

  • if radius is x^4 → flow x^16

what happens to flow if P1 and P2 was the same?

blood flow = 0 → no blood flow

• this is why we need blood pressure otherwise blood wont flow

what is the level of resistance to venous system?

very low

what is resistance?

any force that is against of movement

what happens if resistance of venous system is high?

no flow because there is no pressure

how is resistance of peripheral (arterial) determined?

• by arterioles and pre-capillary arterioles

what is viscosity?

measurement of resistance of liquid to flow

as viscosity increases, what happens to pressure required to flow

pressure required to flow increases

what is the common mean to report viscosity?

to consider viscosity of water as one

what does viscosity of whole blood 3.0-4.5 mean?

3 times more pressure is required to force blood to flow the same as water

viscosity is influenced largely by

hematocrit

what is hematocrit?

volume of packed RBC/volume of whole blood

flow is inversely related to?

viscosity

increase viscosity → increase resistance

what happens when you increase hematocrit?

viscosity is increased

it increases logarithmically

what is critical closing pressure?

pressure at which a blood vessel collapses and blood flow stops

• tissue becomes dead + necrotic

what is laplaces law?

force acting on blood vessel wall is propotional to diameter of the blood vessel times blood pressure

what happens if pressure falls below critical closing point?

• force goes down

• pressure goes down

what is vascular compliance?

measure of distensisibility (expansion) of the volume produced by a unit pressure change

• “rubber is very compliant”

the vessel wall stretches the greater its _____

compliance

venous blood has a large ___1____ and acts as ______2_____

1. compliance

2. blood reservoir

formula for compliances

increase in volume (mL)/increase in pressure (mmHg)

as we become older, our artery walls become

thicker

if you increase blood pressure, what happens to blood volume?

increases blood volume

when is compliance lost?

as we get older

or people who have atherosclerosis

what does elasticity mean?

the quality of recoiling or returning to an original form after the removal of pressure

during ventricular diastole, what does arterial pressure do?

arterial pressure drives blood flow through the vasculature

true or false: compliance of vein are bigger than arteries

true

as diameter of vessels decreases what happens to total cross sectional area and velocity of blood flow?

the total cross sectional area increases

velocity of blood flow decreases → capillaries (velocity should be decreased)

aortic pressure fluctuates from

120-80 mmHg

what is the blood pressure average?

blood pressure averages 100 mmHg in aorta and drops to 0mmHg in the right atrium

greatest drop in pressure occurs?

arterioles → (they offer greatest resistance flow) which regulate flow through tissues

no large fluctuations in

capillaries and veins

for people who have cardiac failure you must reduce

cardiac preload

when venous vessels constrict, what happens to their compliance, venous pressure, and stroke volume

compliance decreases → venous pressure increases favoring venous return and increases stroke volume

venous return to heart increases due to?

1. increase in venous tone

2. increase blood volume

resistance to left ventricular ejection is presented by

systemic vascular resistance

what is pulse pressure

difference between systolic and diastolic pressure

how does pulse pressure increase?

• increases when stroke volume increases or vascular compliance decreases

  • can be used as an early indicator of vascular disease → considered for progression of atheroscelorosis and hypertension

pulse pressure can be used to determine?

heart rate and rythmicity

what does weak pulses indicate?

indicate a decrease stroke volume caused by increased constriction of arteries

constriction of arteries: increase of after load → decreases SV

what is diffusion in capillary exchange?

• distances involved are smaller → happens faster when distance is small

• concentration gradient is larger

• ions or molecules involved are smaller

whether a blood item can diffuse across the capillary or not depends on its _______

chemical nature

nutrients diffuse from

capillaries to interstitial fluid

what are the different nutrients that can diffuse through the capillary exchange?

• water soluble molecules (glucose, AA) → diffuse through endothelial cells

• Ions diffuse bt passing through channels in cell membrane

• lipids soluble gases and steroid hormones diffuse through plasma membrane of ECS

  • not a barrier, since the plasma membrane are base on lipids

• large water molecules unable to leave blood except at kidney and intestine

which nutrient cannot diffuse through the capillary exchange and why?

plasma proteins, they should remain bc if they dont it causes inflammation or other disease to occur

direction of filtration occurs on what 2 pressures?

capillary hydrostatic pressure and blood colloid osmotic pressure

what is filtration

the process of straining the fluid (plasma) out

the driving force of filtration is

hydrostatic pressure

blood pressure in a capillary is the

capillary hydrostatic pressure

what is the direction of pressure for chp and is it constant?

outward pressure

not constant

BP in capillary falls from ___1____ at the ___2____

to ___3____ at the ____4_____ of capillary

1. 35

2. arterial end of capillary

3. 10 mmHg

4. venous end of capillary

filtration occurs primarily at the?

arterial end where CHP is the highest

osmotic pressure exists when

two solutions with different solute concentrations interact

what is the direction of bcop and is it constant?

inward pressure

constant

water always leaves the __1__ solution, __2____ its way into the ___3___

1. hypotonic solution

2. pushing

3. hypertonic solution

which blood is hypertonic and hypotonic?

hypertonic = blood in capillary

hypotonic = blood in interstitial space

BCOP is determine by

plasma protein

if you loose plasma protein → decrease BCOP (causes inflammation/liver disease)

any changes within the CHP and BCOP causes

edema

NFP is equal to the?

CHP - BCOP

if CHP > BCOP (+ number) what happens?

fluid forced out of the capillary

if CHP = BCOP what happens?

no net movement of fluid

BCOP > CHP what happens

fluid moves into capillary → reabsorption

where does the remaining 3L go?

into the lymphatic capillary, which goes to the thoracic vein which becomes the plasma.

capillary hydrostatic pressure tends to what?

push water and solutes out of the capillaries and into interstitial fluids

blood colloid osmotic pressure tends to what?

push water and solutes into capillaries and out of interstitial fluids

pressure in vessels above and below the heart is affected by

gravity

in a standing position, hydrostatic pressure caused by gravity does what to the BP?

increases BP below the heart and decreases BP above the heart

causes of edema?

• increase in permeability of capillaries → inflammation increase the capillary permeability

• decrease in plasma protein (when you lose plasma protein → decreases BCOP)

• blockage of veins

• blockage or removal of lymphatic vessels

what are the functions of the lymphatic system?

• fluid balance

• fat absorption

• defense

explain fluid balance

excess interstitial fluid enters lymphatic capillaries and becomes lymph

explain fat absorption

lymphatic vessels called lacteals located in the lining of small intestine can absorb fat and other substances from digestive tract.

fluid (lymph) passing through the lacteals are called

chyle

microorganisms and other substances are filtered from the lymph by

lymph nodes

blood gets filtered by

spleen

what is lymphatic vessels?

responsible for draining interstitial fluids from tissues (carry lymph away from tissues)

which one is more permeable blood or lymphatic capillaries?

lymphatic capillaries

lymphatic vessels are found in all parts of the body except?

• bone marrow

• tissues without blood vessels → cartilage, cornea, epidermis

lymphatic capillaries join to form

lymphatic vessels

lymphatic vessels have _______ that ensure one way flow

one-way valves

lymphatic vessels join to form

larger lymphatic trunks

lymphatic trunks forms ___1_____ which empty into ___2____

1. thoracic ducts

2. thoracic veins

lymphatic organs contain lymphatic tissue and cells such as

lymphocytes and macrophages

lymphocytes are

white blood cells (B & T cells) derived from bone marrow, but carried by blood to lymphatic organs

what is fine collagen reticular fibers?

• act as a filter to trap microorganisms and other particles in lymph or blood

what is non-encapsulated?

not surrounded by a capsule and acts as first line of attack against invaders → tonsils

what is encapsulated?

lymphatic tissues that is surrounded by a capsule → lymph nodes, spleen, thymus