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EBME202 > Circulation 1 and 2 > Flashcards

Circulation 1 and 2 Flashcards

1
Q

Which cardiac artery is most important and why?

A

Left anterior descending artery b/c it feeds blood to the majority of the front wall of the heart (feeds a much greater area than the other coronary arteries)

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2
Q

Stroke Volume Formula

A

SV = Starting Volume - Ending Volume
= End Diastolic Volume - End Systolic Volume
= EDV - ESV
* Answer should be positive

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3
Q

What is Ejection Fraction and how is it calculated?

A

Percent of blood ejected each heartbeat
EF = (EDV - ESV)/EDV * 100
= SV/EDV * 100
* Normally 55-70%

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4
Q

What is considered high arterial pressure? What is considered normal arterial pressure?

A

High: >160 mmHg
Normal: 80 - 160 mmHg (Varies based on age, exercise, etc)

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5
Q

Calculating Cardiac External Work

A

Cardiac Work = Pressure x Volume

where

Pressure = Mean Arterial Pressure = 2/3 diastolic + 1/3 systolic
Volume = Stroke Volume = EDV - ESV

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6
Q

Diastolic Pressure vs Systolic Pressure

A

Diastolic is pressure between beats (resting)
Systolic is during contraction

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7
Q

What are the units of cardiac external work (stroke work)

A

Work = Pressure x Volume
= mmHg x ml
= N/m^2 x m^3
= Joules (J)

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8
Q

Cardiac Power Formula

A

Power = Cardiac External Work/Time
= Joules x Beats/Second

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9
Q

Poiseuille’s Law

A

Blood flow depends on the pressure difference ΔP, length l, viscosity n, and very strongly on the radius

Q (blood flow) = πΔPr^4/8nl

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10
Q

Resistance to Blood Flow (Formula)

A

R = 8Ln/πr^4

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11
Q

Resistance in Series vs in Parallel

A

Series: Rtotal = R1 + R2 + R3…
Parallel: 1/R1 + 1/R2 + …

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12
Q

Why is blood doping bad?

A

Increases the viscosity of the blood which leads to increase chances of heart disease/stroke/blood clots

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13
Q

What are the 3 methods of measuring cardiac output?

A

Fick’s Method, Indicator Dilution, Echocardiography

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14
Q

Relationship between blood pressure, volume, and blood flow

A

Δ𝑃 = (Blood flow) * Resistance
- Increase in blood pressure means a proportional increase in blood flow
- Increase in blood volume proportionally increases blood pressure

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15
Q

Name the transition of blood vessels from artery to vein

A

artery, arteriole, capillary, venule, vein

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16
Q

Precapillary sphincters

A

Contractile band of cells at the point where each capillary branches from the arteriole
- Vasomotion - cyclical opening and closing of precapillary sphincters

17
Q

Vasoconstriction vs Vasodilation

A

Constriction - contraction of smooth muscle to decrease lumen diameter
Dilation - relaxation of vascular smooth muscle to increase lumen diameter

18
Q

What are the 3 control types?

A

Local control - mechanisms to regulate blood flow to specific tissues (local, acute or long term)
Humoral - control by substances secreted or absorbed into the body fluids (local or systemic, acute or intermediate duration)
Neural - control of circulation by autonomic nervous system (systemic, acute to long term)

19
Q

Types of Local Control

A

Acute Control
- Metabolic Control: regulate blood flow to meet metabolic demands of a tissue
- Autoregulation: regulate blood flow during arterial pressure changes
- Endothelium-derived Factors
Long-term Control
- Angiogenesis: formation of new blood vessels

20
Q

Metabolic Acute Local Control Regulation Types

A

Active Hyperemia - local blood flow temporarily increases to compensate for an increase in tissue metabolism or a decrease in O2 availability
Reactive Hyperemia - temporary elevation of blood flow to repay the tissue oxygen deficit after a period of reduced or blocked blood flow

21
Q

Is adenosine a vasodilator or vasoconstrictor

A

vasodilator (important especially in the heart)

22
Q

What is the Oxygen demand theory

A
  • Metabolic mechanism for acute local regulation of blood flow
  • The degree of vessel contraction depends on the availability of oxygen and nutrients to vascular smooth muscle
23
Q

What is autoregulation

A
  • Acute local regulation of blood flow due to blood pressure change
  • allows blood flow to a tissue/vessel to remain constant despite variations in arterial pressure
  • Myogenic and Metabolic mechanism
24
Q

What are the 2 main endothelium-derived factors

A

Nitric Oxide (vasodilator) and Endothelin (vasoconstrictor)

25
Q

What is the long term local control of blood flow

A

Angiogenesis (formation of new vessels)
- Also remember vascular remodeling (changes to existing vessels in response to long term changes)

26
Q

What are the main 2 humoral control of circulation methods

A

Vasoconstrictors and Vasodilators

27
Q

What parts of the nervous system are involved in neural control of circulation?

A

Autonomic Nervous System
- Sympathetic (more important)
- Parasympathetic (plays minor role in regulating circulation)

28
Q

What does the Nervous System primarily regulate

A

Blood Pressure

29
Q

What is the vasomotor center and the subareas of this structure

A

Vasomotor Center - structure responsible for controlling autonomic modulation of circulation in the medulla and pons
- Vasoconstrictor area
- Vasodilator area
- Sensory area

30
Q

What is the primary vasoconstrictor neurotransmitter in the sympathetic nervous system

A

Norepiniphrine

31
Q

What is vasomotor tone?

A

The constant state of partial constriction of blood vessels throughout the body

32
Q

What is the baroreceptor reflex

A
  • Negative feedback stretch reflex
  • Baroreceptors send signals to CNS in response to high blood pressure
  • Firing rate increases with arterial pressure
  • Veins/arterioles vasodilate and heart rate decreases
  • Decreases blood pressure
33
Q

What is the chemoreceptor reflex

A
  • Chemoreceptors in the carotid/aortic bodies detect low oxygen, high CO2, or high hydrogen ion levels in the blood
  • The receptors are activated by low blood pressure
  • Signal sent to the vasomotor center of the CNS which elevates blood pressure
  • Important for preventing too low of a blood pressure
34
Q

What is the CNS Ischemic Response

A
  • Cerebral Ischemia: blood flow to the brain isn’t sufficient to meet the brain’s metabolic needs
  • Vasomotor center detects cerebral ischemia and activates vasoconstrictor/cardioaccelerator neurons
  • Result: Blood pressure increases to increase blood flow to the brain
  • EMERGENCY RESPONSE (last resort when blood is extremely low to the brain)
35
Q

What are the primary functions of local, humoral, and neural control

A

Local - regulate blood flow
Humoral - regulate blood flow or blood pressure
Neural - regulate blood pressure

EBME202 (6 decks)

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