Cardiovascular Normal Function Part 2 Flashcards
Closed Circulatory System
Humans (all vertebrates), blood never ____ vessels, movement of gases, O2, CO2, glucose, fatty acids move through ____ and exchage at ____ level
______: tiny arteries that provide blood flow to capillary beds throughout the body
_____ _____: site of exchange between blood and tissue
______: tiny veins that drain blood back to right side of heart
Are THICK bc are lax, ___ resistance/non ______ vessels
leaves, diffusion, tissue
Arterioles
Capillary Beds
Venules
low resistance, non-muscular
Flow Dynamics
F = ►P/R
- F =
- ►P =
- R =
- Flow rate through vessel
- Pressure gradient
- Resistance of blood vessel
Flow Dynamics Notes
- Flow rate = v_____ per t____
- Pressure gradient = P_____ pressure
- Pressure gradient/Resistance = _______ related
Resistance to flow comes from 2 things
-
_______: (thickness) of blood determined by ______: ratio of cells to plasma
- High viscosity =
- ______ of Vessel*: relationship between r_____ and r______ is ______ (small change in radius produces big changes in resistance
- volume per time
- perfusion
- inversely
-
Viscosity, Hematocrit
- Lot of cells, Low plasma
-
Diameter, radius and resistance
- Exponential
Radius vs. Resistance
- Smaller Radius -> ______ Resistance -> ______ in flow
- Bigger Radius (______) -> _____ Resistance -> ____ in flow
In the picture, the diameter increases by __x but the flow increases by ___x
- higher -> decrease
- Dilation -> lower -> increase
2x diameter -> 16x flow
Arteries
The arteries are designed to perform two major duties:
- Fast _____ from heart to tissues (____ diameter vessels)
- _____ pressure and provide _____ force for flow when heart is resting (elastic walls)
Connective tissue layer ______ and _____ fibers
Underlying _____ _____
External _____ _____ covering
- transport (large)
- Store, driving force
collagen and elastin
smooth muscle
connective tissue
Arteries as a Pressure Reservoir
Pressure transfers from ventricular _____ -> ____ on aortic wall -> perfusion pressure during diastole when aortic wall ______
contraction -> stretch -> rebound
What is happening in this picture?
The energy is transferred into?
Driving Force
Arterial Blood Pressure
Blood Pressure - ____ of blood against vessel wall
Compliance and Distensibility
- Arteries compliance?
- Veins compliance?
Notes
- BP = indirectly measuring _____ pressure by measuring ____ artery pressure
- Systolic = ____ arterial pressure (generated by systolic contraction of ventricles)
- Diastolic = ____ pressure of arteries (generated by how healthy artery walls are and blood volume)
force
- not very compliant
- very compliant
- aortic, brachial
- peak
- resting
Arterial Blood Pressure
- Systolic: ____ average
- Diastolic: ___ average
(1): Difference between systolic and diastolic pressure
- represents the potential for _____
- Lower pulse pressure = less ____ ventricles can push into aorta
(1): constant perfusion pressure that is present in the arteries no matter what phase your heart is in
- ADEQUATE MAP = _____ OF ______
- weights _____ pressure > _____ pressure bc your BP spends more time closer to diastolic than it does to systolic
- MAP = ____ + _____
- 120
- 80
Pulse Pressure
- Perfusion
- blood
MAP
- PERFUSION OF ORGANS
- diastolic > systolic
- Diastolic pressure + 1/3 pulse pressure
Manual BP
Pump up bladder until you lose ____ pulse: this represents when cuff pressure is just ____ systolic pressure (just harder than the peak pushing pressure of that artery)
lose radial pulse -> above SBP
Korotkoff Sounds
- Green line = Cuff Pressure
- Tapping sounds = _____ blood flow
- ___ radial pulse left
- First tap =
- Last tap =
- Both numbers when taking manual BP are ________ (slightly less than systolic and diastolic)
- turbulent
- No
- Comes from force of blood that comes through the squeezed brachial artery that represents cuff pressure just below systolic pressure
- When cuff pressure falls just below diastolic pressure
- underestimations
Oscillation of Pressures through the Vascular Tree
Gradual ____ of MAP through arteries, arterials, veins promote movement of blood in that _____ way
- Left ventricle:
- Systemic arteries:
- Arterioles:
- Capillaries and Veins:
Decline
- 0-120
- 80-120
- starts to lose pulse pressure
- completely looses pulsatile nature
Arterioles
- Supplies Organs
- Arteriole walls very simplified compared to arteries -> very ____ connective tissue**, still has ____ _____ covering
- Diameter changeable
- ______ distributes CO based on current _____: “_______” to blood entering an organ
- Regulates arterial _____ _____: bc has signficant ability to ____ and ____ -> effects overall _____ in the system
- Supplies Organs
- little connective tissue**, smooth muscle
- Diameter changeable
- Variably distributes CO, demands, “gatekeepers”
- BP: constrict and dilate -> resistance
Arteriole Tone
What Factors Cause Vasoconstriction or Vasodilation
Normal Arteriolar Tone =
Produced by:
1)
2)
Resting diameter of arterial produced by basic properties of muscles that surround arterioles and baseline SNS output
1) Myogenic activity - elastic property of the muscle tissue
2) Baseline sympathetic input
What Factors Cause Vasoconstriction or Vasodilation?
Factors fall into two general categories:
Intrinsic Factors (1)
Extrinsic Factors (2)
Local Factors
Neuronal or Hormonal Factors
Intrinsic Local Control
= Changes with ______
- Chemical (2)
- Physical (2)
Tissue
-
Chemical
- Local metabolic changes
- Histamine release
-
Physical
- Local application of heat or cold
- Myogenic response to stretch
Local Control - Chemical Factors
- Local Metabolic Changes (4)
- Vasoconstriction
- O2 =
- CO2 =
- Acidity =
- Adenosine =
- Vasodilation
- O2 =
- CO2 =
- Acidity =
- Adenosine =
O2, CO2, Acidity, Adenosine
- Vasoconstriction
- Increased
- Decreased
- Decreased
- Decreased
- Vasodilation
- Decreased
- Increased
- Increased
- Increased
Local Metabolic Changes Notes
Free ____ increases whenever you are consuming ATP
______ Cells: Critical player in local control, cells that directly face the blood and sense changes in O2, CO2, Acidity, Adenosine
Endothelial Cells will Release what during
- High Metabolic Activity (1)
- Low Metabolic Activity (1)
Adenosine
Endothelial Cells
-
Nitric Oxide: gas that acts on smooth muscle to dilate vessel when tissue is very metabolically active (low O2), so dilation will dilate to increase perfusion and O2 delivery to tissue
- EDRF = Endothelial Relaxing Factor (first name for NO)
- Endothelin: substance that goes next door to smooth muscle to cause vasoconstriction -> shunts blood to somewhere else where is most needed
Extrinsic Control
Includes both _____ and ______ influences
Most important is the effect of?
Sympathetic nerve fibers supply arteriole smooth muscle everywhere but the brain
- Increased activity = generalized ______
- Decreased activity = generalized ______
Releases what hormone? - onto what receptors?
Helps regulate _____ _____
neural and hormonal
Sympathetic nervous system
- vasoconstriction
- vasodilation
Norepi -> alpha-adrenergic receptors
Blood pressure
Extrinsic Control Notes
Increased sympathetic activity
- Total peripheral resistance?
- CO = HR x SV -> HR? SV?
- Vaso_____ on vein -> increases venous ______ -> increase end ____ volume -> more ___ volume
Generalized vasoconstriction is the NET effect - Think Fight or Flight (Sympathetic Response)
- Specific effect that sympathetic stimulation has to a particular arterial bed depends on ____ that arterial bed resides
- Arterioles that perfuse smooth muscle and bronchioles have ____ receptors
- Norepi binds to beta receptors causes = ______
- Arterioles that perfuse nearly all other organs have ____ receptors
- Norepi binds to alpha receptors causes = ______
- TPR increases
- HR and SV increases
- constriction -> return -> diastolic volume -> stroke
- where
- Beta
- Vasodilation (allows you to RUN/FLEE)
- Alpha
- Vasoconstriction (blood flow shunts away from GI/liver/kidneys)
How does Arteriole Diameter relate to Blood Pressure?
F = ►P/R
Cardiac Output (CO) =
Mean Arterial Pressure (MAP) =
Total Peripheral Resistance (TPR) =
CO = MAP/TPR or MAP = CO x TPR therefore..
TPR most influenced by _____ resistance
CO = Flow
MAP = ►P
TPR = R
Arteriolar Resistance
TPR is a function of blood viscosity (hematocrit) AND overall arterial constriction vs. dilation
Relationship between CO and MAP - positive association
So depending on what arterioles are doing TPR goes up and down which causes our MAP to go up or down
Constant Pressure in pipe (MAP)
High resistance = ___ flow
Moderate resistance = ___ flow
High resistance = ____ flow
Beakers = Organs, Outlets = Arterioles
No
Moderate
High
Distribution of CO Rest vs. during Exercise
- Total CO?
- Blood flow to Skeletal Muscle?
- Blood flow to Heart?
- Blood flow to Brain?
- Blood flow to Skin?
- Blood flow to Organs?
- Total CO expands
- Increases by over 1000% (5L/min -> 12.5L/min)
- Increases
- Fixed amount, doesn’t change
- Gets more (so it can dissipate heat so our core temp doesn’t go up)
- Gets LESS
Hormonal Influence on Arteriolar Diameter
______ Activity
Hormones (2)
What gland does it act on?
Sympathetic
Epinephrine and Norepinephrine
Adrenal Gland (Cortex and Medulla)
Hormonal Influence on Arteriolar Diameter
-
Epinephrine
- Greater affinity for what receptor?
- Effect?
-
Norepinephrine
- Greater affinity for what receptor?
- Effect?
- Beta receptors located on arteries that perfuse skeletal muscle and bronchioles
- Vasodilation -> ability to run/flee
- Alpha receptors on organs
- Vasoconstriction -> shunts blood away from organs
Hormonal Influence on Arteriolar Diameter
(2)
That both cause Vasoconstriction
Vasopressin (Water balance)
Angiotensin II (Plasma volume-Sodium)
Capillaries
The sites of exchange of all material between blood and tissues
- Highly adapted for ________
- Diffusion ______ is minimized
- _____ of diffusion barrier is minimized
- Tremendous ______ _______ available for diffusion (600m2)
- Blood velocity ______ through capillary beds
- Diffusion
- distance
- Thickness
- Surfance Area
- Slows
Most of the time the mechanism of exchange is simple diffusion
“Capillary beds (bodies exhibit) are so dense, so many, huge surface area, etc”
Speed of RBC traveling through capillaries slows down -> to increase opportunity for exchange
Cross-Sectional Area and Velocity of Capillaries
What happens to these as it moves toward the Capillary Beds
- Cross Sectional Area (cm2):
- Velocity (mm/sec):
-
Flow Rate (L/min):
- Equation: Flow rate = __ x __
- Increases dramatically (more area available for diffusion) -> which also contributes to slowing blood velocity
- Slows so more opportunity for exchange
- NEVER changes by
- Cross sectional area of arteries and veins is the same
- As cross sectional area inreases in capillaries, velocity goes down
- total cross sectional area x velocity
Capillary Structure
(1): Little gaps between endothelial cells that allows for diffusion
- They make the capillaries very ______ which is unlike the capillaires in the ____ that make up the ____
- What can pass through?
- What cannot pass through?
Pores
- leaky, brain, BBB
- Glucose, Ions, Fluid
- Plasma proteins and cells (RBC, platelets, WBC)
Transport Across Capillary Wall
- (2) = Lipid soluble (nonpolar) substances that pass through endothelial cells
- (4) = Small, water-soluble substances that pass through pores
- (1) = Cannot cross the capillary wall
- (1) = Moved across by vesicular transport
- O2, CO2
- Na, K, glucose, AA
- Plasma proteins (Albumin) are retained
- Exchangeable proteins (like antibodies use endo/exocytosis)
Capillary Bed Components
(1): slightly larger than capillary vessels and represents vessels with a smaller cross sectional area than the capillaries that surround them
(1): little bands of smooth muscle that lie in between capillary vessels and metaarterioles so that when they’re constricted most blood flows through the meta-arteriole
- What does this mean for tissue if blood is just going through metaarterioles?
-
Tightness of Sphincters is Controlled by Local Metabolic Activity of that Tissue
- High metabolic need -> want more blood flow through _____ -> causes precapillary sphincters to _____
- Low metabolic need -> want more blood flow through ____ so causes precapillary sphincters to _____, so blood can do what?
Meta-arterioles
Precapillary Sphincters
-
Less opportunity for exchange but will be able to get from arterioles to venules faster
- capillaries, RELAX
- metaarterioles, CONSTRICT (so blood can quickly return and be sent somewhere else)
Transport Across Capillary
Vast majority of time exchange is through?
In this picture what uses a carrier mediated transport?
Simple diffusion
Glucose
Purpose of Bulk Flow
Capillary Bulk Flow: ______ PROCESS to REGULATE DISTRIBUTION of ____ between _____ and ______ components
- (1): NET movement into capillary
- (1): NET movement out of capillary
-
(1): Pushing pressures
- (2)
-
(1): Pulling pressures
- (2)
High metabolic activity -> blood flows through capillary beds -> net _______
Low metabolic activity -> low capillary blood pressure -> net _______
PASSIVE, ECF, Plasma (intravascular) and Interstitial
- Reabsorption
- Ultrafiltration
-
Hydrostatic Pressure
- Interstitial hydrostatic pressure (reabsorption)
- Capillary blood pressure (ultrafiltration)
-
Oncotic Pressure (exerted by plasma protein (albumin))
- Interstitial Oncotic Pressure (ultrafiltration) - usually 0 bc no albumin
- Plasma Oncotic Pressure (reabsorption)*** stable in a normal human, deficiency from starvation/liver failure -> ascites
ULTRAFILTRATION
REABSORPTION
Venous System
______ Vessels
Blood ______
- Highly _____ and Highly _____ bc not much smooth muscle in their walls-> _____ readily when blood enters
- Therefore often described as our Blood ______
- __% of blood in systemic veins at rest
- When we need, all we have to do is ______ stimulate them to _____/become __compliant and blood will be forced to move onto heart increasing venous return
- Total Blood Volume vs. ______ Circulating Blood Volume
Capitance
Reservoir*
- Compliant, Capitance, accomodate
-
Reservoir
- 64%
- sympathetically, constrict, non
- Effective
Veins
(1): Volume of blood that the veins can accommodate
(1): Volume of blood entering each atria from the venous vessels
Factors tht influence venous return
- _______ induced venous vasoconstriction
- Skeletal ______ activity
- Effects of venous _____
- R______ activity
- Cardiac s______
Venous Capacity
Venous Return
- Sympathetically
- Muscle - when i contract mucles in my legs, i milk blood up to heart (works bc veins have valves which make blood move in one direction towards heart)
- Valves
- Respiratory - pressure in thoracic cavity diff in pressure compared to abdominal pressure
- Suction
Sympathetically Induced Venous Vasoconstriction
Sympathetic Activity -> ______ Compliance -> _____ Venous Return
Decreased Compliance -> Increase Venous Return
Skeletal Muscle Activity
Orthostatic Hypotension/Syncope happens bc?
- _______ Venous Return
- _______ CO
- _______ MAP
blood pools in lower extremities when standing not enough CO for MAP/perfuse brain - so trick is to contract muscle in legs occasionally
- Decreased
- Decreased
- Decreased
Effect of Venous Valves on Venous Return
Open venous valve:
Contracted skeletal muscle:
Closed venous valve:
Permites blood flow of blood toward heart
Pushes blood both ways
Prevents backflow of blood
Effect on Respiratory Activity on Venous Return
Pressure in thoracic cavity compared to abdominal and atmospheric pressure is?
Less pressure in thoracic cavity encourages movement of blood to heart as it gets closer to diaphragm
Effects of Cardiac Sunction on Venous Return
The heart plays a role in its own filling
Ventricles contract -> atrial volume increases -> _____ pressure -> enhances venous ______
Ventricles relax and expanding in volume -> enhanced ventricular _____
negative pressure -> enhances venous return
filling
Blood Pressure
____ is the main driving force in supplying blood to tissue
- Too low =
- Too high =
- MAP = ___ x ___
MAP
- inadequate perfusion
- increased workload of heart
MAP = perfusion pressure must maintain adequate MAP -> but if it gets too high ends up increasing workload of heart and causes heart problems
What Determines TPR?
(2)
Determined by (2) factors
Blood Viscosity (hematocrit)
Arteriolar Radius
- Local factors: skeletal muscle activity, general metabolic activity
- Extrinsic factors: sympathetic nervous activity (epi and hormones like vasopressin, angiotensin)
What Determines CO?
(2)
HR: slowed by PNS, sped up by SNS
SV: effected directly through sympathetic nerve or enhancment of venous return
Control of MAP
Control systems for MAP can be divided into two categories:
- ____-term regulation =
- ____-term regulation =
- Short term = Baroceptor Reflex
- Long term = Renal System by regulating plasma volume through RAAS
Baroceptor Reflex
Control BP on a ___ to ____ basis by measuring what?
2 locations - neural signals to?
moment to moment, constantly measuring stretch on artery wall
Aortic Arch baroceptor
Carotid Sinus baroreceptor
CV control center in medulla
Baroreceptors Reflex Firing Rates
- When BP is normal:
- When BP is increased:
- When BP is decreased:
Why only short term regulation?
- normal firing rate
- INCREASE firing rate
- DECREASE firing rate
Bc they adapt/v sensitive to any change in BP -> if elevated BP is sustained, baroceptors will adapt and firing rate will go back to normal, they don’t remember what BP was like more than a few min ago
Baroreceptor Reflex
Baroceptors sense change and signals CV center in _____ -> medulla increases ____ nerve activity to __ node in heart -> ______ HR -> decreasing HR will decrease ___ -> decreased ____
Adjusting __ is the big step
medulla -> vagus, SA -> Decrease HR -> CO -> MAP
HR
Baroreceptor Reflex Outputs (example)-Responding to INCREASED MAP
Not only do we adjust HR but we affect level of _____ stimulation to arterioles and veins to cause constriction or dilation within vessels
^PNS =
Decreased SNS =
sympathetic
= decrease HR -> decrease CO -> decrease BP
= decrease HR -> vasoconstriction of arterioles and veins -> decrease BP
Long term Regulation of BP
_____ Influences in Plasma volume
- ____ Mechanism
- _____ output
- _____ balance
When BP is too high -> _____ plasma volume
When BP is too low -> _____ plasma volume
Renal
- Thirst
- Urine
- Salt
Decrease
Increase
