HBIO420L Quiz #3

Blood Pressure

force of blood distending arterial walls

Expressed as systolic/dystolic mmHg

Systolic BP (SBP)

Highest pressure in arteries during left ventricular contraction

Diastolic BP

Lowest pressure in the arteries during left ventricular relaxation

SBP <90mmHg

Hypotension

Considered acceptable (<90mmHg SBP) if:

Dizziness

Syncope

Coldness

Pallor

Nausea

Low urine output

High arterial [blood lactate]

Mean Arterial Pressure MAP

average P in arteries during 1 cardiac cycle

driving force of blood → vascular system

Pulse pressure (PP) needed to calculate MAP: what is the formula?

PP = SBP - DBP

MAP is not an average of systolic/diastolic values. Why?

At rest → more time spent in diastole during a cardiac cycle > systole

During exercise → more time spent in systole during a cardiac cycle than diastole

Calculate MAP at rest

(SBP-DBP)/3 + DBP

Calculate Map during exercise

MAP = (SBP-DBP)/2 + DBP

Normal MAP (at rest values are around…)

70-100mmHg

<70-100mmHg (MAP Values at rest means what)

Low perfusion

>70-100mmHg (MAP Values at rest means what)

High resistance

MAP can reach up to… during exercise

155mmHg+

Total Peripheral Resistance (TPR) consists of

Vessel Diameter

Blood Viscosity

Total Vessel Length

CO is _________ to SBP

directly proportional

TPR is ________ to _____

directly proportional to BP

Arterial BV is _______ to SBP

directly proportional

Arterial compliance/vessel elasticity

Indirectly proportional to BP

Cardiac Output

Volume of blood ejected from LV/min

Frank-Starling Law of Heart

Venous return to heart → increase EDV

Stretch of ___________ of ventricle

_____ force

______ vol

_______ CO

myocardial fibers

contraction,

contraction

Stroke

increase (all)

TPR - Total Peripheral Resistance

Force produced between blood & walls of blood vessel

TPR is __________ to diameter

indirectly proportional

Vasomotor Tone

aMount of vasoconstriction of arteriole vessel (SNS)

Vasoconstriction will → to ______ vessel diameter

decrease

Viscosity

Physical property related → ease which fluid molecules flow past one another

TPR is ________ to viscosity

directly ppt

What factors decrease viscosity/hct

Anemia, Hemorrhage

Increased BT

Factors that increase viscosity/hct

Excess RBC

Cold temp

TPR is ____ to vessel length

directly ppt

Obesity decreases vessel length

F

body fat (increase) → increases no. of BV →

increases vessel length → TPR increase

Arterial BV to SBP

Arterial BV ppt to SBP

Excess na+ →

Increase BV

Dehydration, blood loss →

Blood Vol Decrease

Arterial Compliance/Vessel Elasticity

BP is indirectly ppt to material compliance (elasticity of artery walls)

Increase Arterial Compliance →

Decrease BP

HR * SV = Q

How to calculate CO

BV, HR, SV, Blood Viscosity, Peripheral Resistance increase →

BP increase

Baroreceptors (carotid a. & aortic arch) monitor

BP

Short term reg. is controlled by the sympathetic and parasympathetic nervous system by changes in:

HR, Contractility, Arterial Diameter

Environmental Factors Affecting BP

Exercise → steady-state/resistance

Body position → orthostatic hypotension, inversion

SBP increases with…

intensity increase, but no change in DBP (little)

TPR increases with resistance and upper-body exercise

T

TPR increaess/decreases with steady state aerobics

decreases

Q increases with graded exercise

T

Supine (vs seated upright) ↑ BP

Decreases gravity resistance > ↑ Venous Return ↑ EDV, ↑ SV > ↑ Q and ↑ BP

→ ↑ in SBP (6-7 mmHg) but (1mmhg DBP)

Standing (vs seated upright) ↓ BP

↑ Gravity Resistance > ↓ Venous Return > ↓ EDV ↓ SV ↓ Q ↓ BP

Orthostatic intolerance

↓ in BP with change in posture