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Flashcards in Physiology Deck (185)
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Three pressures in the CV system?

1. Driving (difference between two points)

2. Hydrostatic (P of gravity and weight of blood)

3. Transmural (P of blood on vessel wall)


Arteriolar resistance is regulated by the _1_ nervous system.

1. Autonomic


Arteries are under _1_ pressure and Veins are under _2_ pressure.

1. High

2. Low


Blood flows from __1 (high/low)__ pressure to __2 (high/low)__ pressure. The __3__ drives blood flow.

1. High

2. Low

3. Pressure gradient


Blood flow is inversely proportional to the _1_ of blood vessels. When blood flow increases, _1_ has decreased.

1. Resistance (nothing is holding it back)


What is the equation for blood flow/cardiac output/Q?

CO = (Mean arterial pressure [highest P] - Right arterial pressure [lowest P]) / (Total peripheral resistance [TPR])


What are the factors that change the resistance of blood vessels (3)?

1. Viscosity of blood (numerator)

2. Length of blood vessel (numerator)

3. Radius of blood vessel to the fourth power (denominator)

Resistance = (8*visc*length)/(pi*r^4)


What is viscosity?

Increased viscosity is due to increased internal friction.

  • thickness
  • the state of being thick, sticky, and semifluid in consistency
  • a measure of its resistance to gradual deformation by shear stress or tensile stress


Increasing viscosity by increasing hematocrit will _1_ resistance and _2_ blood flow.

1. increase

2. decrease


Increasing the length of a vessel will _1_ resistance. Increasing the radius of a vessel _2_ resistance.

1. increase

2. decrease


If a blood vessel radius decreases by a factor of 2 then resistance _1_ by a factor of _2_ and blood flow _3_ by a factor of _4_.

1. increases

2. 16

3. decreases

4. 16


_1_ resistance is illustrated by systemic circulation. Each artery in _1_ receives a fraction of the total blood flow. 



When an artery is added in parallel, the total resistance _1_. In each parallel artery, the pressure is the _2_.

1. decreases

2. same


_1_ resistance is illustrated by the arrangement of blood vessels in a given organ. _2_ are the largest contributers to this resistance.

1. Series

2. Arterioles


As blood flows through the series of blood vessels, pressure _1_. Each blood vessel in series receives the _2_ total blood flow.

1. decreases

2. same


_1_ flow is streamlined. _2_ flow is not and causes audible vibrations called _3_.

1. Laminar

2. Turbulent

3. bruits


A _1_ number predicts whether blood flow will be turbulent or laminar. 

Reynold's number


An increased Reynold's number increases the likelihood of _1 (laminar/turbulent)_ flow.



What are the two factors that increase a Reynold's number?

1. Decreased blood viscosity (ex. anemia, lower hematocrit)

2. Increased blood velocity (ex. narrowing of a vessel [decreased radius)


What is hematocrit?

the volume percentage of red blood cells in blood


Pulse pressure is the difference between _1_ and _2_ presures.

1. systolic

2. diastolic


Aging leads to a _1_ in capacitacne and an _2_ in pulse pressure.

1. decrease

2. increase


When is systolic pressure measured?

After the heart contracts (systole) and blood is ejected in the arterial system.


When in diastolic pressure measured?

When the heart is relaxed (diastole) and blood is returned to the heart via the veins.


Systolic pressure is the _1 (highest/lowest)_ arterial pressure during a cardiac cycle. Diastolic pressure is the _2 (highest/lowest)_ arterial pressure during a cardiac cycle.

1. highest

2. lowest


Mean arterial pressure = ?

MAP = 1/3 Systolic P + 2/3 Diastolic P

*because most of the cardiac cycle is spent in diastole


Venous pressure is very _1 (high/low)_. Veins have a _2 (high/low)_ capacitance and therefore can hold  _3 (large/small)_ volumes of blood at low pressure.

1. low

2. high

3. large

*Capacitance is proportional to volume (numerator) and inversely proportional to pressure. As a person ages, their arteries become stiffer and less distensible/stretchy therefore capacitane of arteries decreases with age.


what are 4 methods of regulating arterial blood pressure?

  1. Increase pumping force
  2. contract veins and arterioles
  3. infuse fluids
  4. administer vasoconstrictors


which ventricle has a thicker muscular layer? why?

the left ventricle. It must pump blood through to aorta to systemic circulation.


how does the heart contract?

in a spiral contraction (like wringing a washcloth)