Regulation Of Blood Flow

Question 1

What is the Fick Principal of Flow?

Answer 1

Q (CO) = VO2/ CaO2-CvO2

Question 2

How do you apply the Fick Principal of Flow to Calculate VO2?

Answer 2

VO2= Q (CO) x (CaO2-CvO2)

Question 3

Oxygen Delivery depends on these 2 factors?

Answer 3

1. Q (CO)

2. CaO2

Question 4

A decrease in PvO2 or SvO2 means what in terms of VO2 and Q/CaO2?

Answer 4

1. ⬆️VO2
   Or
2. ⬇️Q or ⬇️CaO2

Question 5

What is intrinsic regulation or autoregulation?

Answer 5

It is the local regulation of Flow

Question 6

Two (2) main mechanisms that explain Intrinsic Regulation?

Answer 6

1. Metabolic Mechanism (K+, H+, Adenosine, Lactic acid, CO2).
2. Myogenic regulation.

Question 7

Explain Myogenic Mechanism?

Answer 7

1. ⬆️Flow –> ⬆️Tone

2. ⬆️⬆️Flow –> autoregulation –> ⬆️Tone—> Flow doesn’t increase as much

Question 8

Crucial Characteristic of Intrinsic Regulation that differentiates from Extrinsic Regulation?

Answer 8

No involvement of:

1. SNS or PNS
2. Hormones

Question 9

Name Most Important Autoregulating Tissues?!?

Answer 9

1. Cerebral Tissue
2. Coronary Arteries
3. Skeletal Muscle during exercise

Question 10

Extrinsic Regulation is regulated 👀 by which mechanisms?

Answer 10

1. SNS > PNS (penis)

2. Hormonal Factors (e.g., NE, Epi, RAAS)

Question 11

Primary FACTORS for Extrinsic Regulation?

Answer 11

1. NE via ALPHA-1 Gq receptors! (Tonic Effect) –> Resting Muscle/Skin
2. Epi via BETA-2 Gs receptors–> Vasodilation
3. PSN almost no effect (exception of penis 🍆)

Question 12

Difference in control between Resting and Exercising Muscle?

Answer 12

1. RESTING: ALPHA-1 ⬆️ or ⬇️ sympathetic stimulus
2. EXERCISING:
   A. Intrinsic Regulation (K+, H+, NO, Adenosine, Lactic Acid) DILATION
   B. Muscle Pump

Question 13

3 Mechanisms that regulate Coronary Blood Flow?

Answer 13

1. Diastole and Systole
2. Oxygen consumption/demand.
3. Pumping action. (CO)

Question 14

Explain regulations in blood flow in the coronaries during the Cardiac Cycle?

Answer 14

• *Left Ventricle: **
  1. MOST blood flow occurs during diastole.
  2. Specially in Subendocardic
  3. Systole: SOME Subepicardic
• *Right Ventricle: **
  1. Significant Flow in Systole
  2. MOST during Diastole

Question 15

Why is PvO2 so low in the coronary circulation?

Answer 15

1. Coronary circulation has de highest VO2 in a resting individual.

Therefore ⬆️VO2 –> ⬆️Q (Flow)

Question 16

Relationship between coronary blood flow and pumping action (CO)?

Answer 16

1. CO= SV x HR 
          = 
A. PRESSURE WORK
    -HR
    -Contractility 
    -Afterload 
B. VOLUME WORK 
     -Preload 
C. Pressure work > Volume work

Question 17

Principal Regulator of Cerebral Blood Flow?

Answer 17

1. CO2
   ⬆️CO2–> ⬆️Blood Flow
   ⬇️CO2–> ⬇️Blood Flow
2. As long as O2 is high or within normal.

Question 18

How is the Cutaneous Circulation Regulated?

Answer 18

1. Sympathetic NS.
2. Arteriolar and Venous Constriction
3. Temperature ⬆️–> Vasodilation

Question 19

Regulation of Skin Flow during fever?

Answer 19

1. Fever Rises: Preservation and Generation of Heat: 
A. Vasoconstriction 
B. Shivering 
2. Fever Breaks ⬇️: 
Mechanism to Loose Heat
A. Vasodilation 
B. Sweating

Question 20

Splanchnic regulation of blood flow?

Answer 20

1. Stress: ⬆️Sympathetic –> ⬇️Flow

2. Digestion: ⬇️Sympathetic –> ⬆️Flow

Question 21

% of CO that goes into the Splanchnic Circulation?

Answer 21

1. 25%

Question 22

Name 3 main Characteristics of the Pulmonary Circuit?

Answer 22

1. Low Pressure Circuit A 15 mmHg –> P 5 mmHg
2. ⬆️Flow (CO)
3. ⬇️ Resistance (vessels are VERY COMPLIANT)

Question 23

Pulmonary Circuit Changes with Exercise ?

Answer 23

1. ⬆️Flow (CO)
2. ⬆️ Compliance
3. ⬇️Resistance (PVR)
4. Small increase in Pulmonary Pressures

Pulmonary P= ⬆️Q (CO) x ⬇️PVR

Question 24

Pulmonary Circuit Response during Hemorrhage ?

Answer 24

1. ⬇️Q (CO) –>
2. ⬆️ PVR–>
3. Small decrease in pulmonary pressure

Pulmonary P= ⬇️Q(CO) x ⬆️PVR