Short Term Regulation of Arterial Blood Pressure

Question 1

Sympathetic Nervous System

Answer 1

(Fight or Flight)

Question 2

Integrators

Answer 2

Subthalamic Locomotor Region, Cardiovascular Control Center (CVC)

Question 3

Subthalamic Locomotor Region

Answer 3

Control Center

Question 4

Subthalamic Locomotor Region Affects

Answer 4

Heart Rate, Arterial BP, LV Contractility

Question 5

Subthalamic Locomotor Region Mechanism of Control

Answer 5

CVC

Question 6

Subthalamic Locomotor Region Functions

Answer 6

Motor unit recruitment, Ventilatory Control

Question 7

Cardiovascular Control Center (CVC)

Answer 7

Reticular Formation (Medulla and Pons; Effector arm of circulatory control (Efferent)

Question 8

How many loose cnx of nerves are in medulla?

Answer 8

5 main areas (Pressor, Depressor, Cardioacceleration Center, Cardioinhibitory Center, Nucleus Tractus Solitarius

Question 9

Pressor Area (cnx of nerves in medulla)

Answer 9

Increase BP via Increased Vasoconstriction (Increase Sympathetic Tone)

Question 10

Depressor Area (cnx of nerves in medulla)

Answer 10

Reverse of Pressor (Decrease Sympathetic Tone)

Question 11

Cardioacceleration Center (cnx of nerves in medulla)

Answer 11

Decrease HR (Via Cardiac Accel. Nerves)

Question 12

Cardioinhibitory Center (cnx of nerves in medulla)

Answer 12

Decrease Heart Rate (Via Vagus Nerves)

Question 13

Nucleus Tractus Solitarius (NTS) (cnx of nerves in medulla)

Answer 13

Receives afferent feedback from chemoreceptors and baroreceptors

Question 14

What is the CVC effector?

Answer 14

The ANS

Question 15

Afferents

Answer 15

Hypothalamus, Chemoreceptors, Baroreceptors, Muscle Afferents

Question 16

Hypothalamus (Afferent) Function

Answer 16

Influence circulation in response to Δ Tcore (set point)

Question 17

Hypothalamus (Afferent) Action

Answer 17

Afferent feedback to CVC (the effector)

Question 18

Hypothalamus (Afferent) Opposing Messages

Answer 18

Hot= Anterior Hypothalamus, Cutaneous Vasodilation; Cold= Posterior Hypothalamus, Cutaneous Vasoconstriction

Question 19

Chemoreceptors (Afferent) Multiple Locations

Answer 19

Peripheral> Aortic/ Carotid> Detects increase in pCO2, Decrease in pO2, and decrease in pH; Central> Medullary> Detects decrease in pH, increase in pCO2

Question 20

Chemoreceptors (Afferent) Function

Answer 20

Sensitive to PCO2, PO2, pH (set point)

Question 21

Chemoreceptors (Afferent) Action

Answer 21

Afferent signal to CVC via glossopharyngeal and vagus nerves, Causes inhibition of pressure center, Coordinates ventilatory response, High Metabolic Activity= Increased firing frequency, Low Metabolic Activity= Decreased firing frequency

Question 22

Baroreceptors (Afferent) Major Arteries (high pressure)

Answer 22

Carotid Sinus> Glossopharyngeal> NTS; Aortic Arch> Vagus> NTS

Question 23

Baroreceptors (Afferent) Heart (low pressure)

Answer 23

Atria; Decreased BP signals posterior pituitary, Increased BP causes atrial myocytes to release anti-aldosterone (ANP)

Question 24

Baroreceptors (Afferent) Function

Answer 24

Sensitive to BP

Question 25

Baroreceptors (Afferent) Action

Answer 25

Signal CVC (inhibit pressor center) via glossopharyngeal and vagus; High Flow= Increased firing frequency, Low Flow= Decreased firing frequency

Question 26

Exercise Baroreflex

Answer 26

HR and BP increase immediately during exercise by baroreceptor “Resetting” to an increased set point; Baroreceptors play a critical role in active skeletal muscle circulation by allowing muscle vasodilation when pressure is high and muscle vasoconstriction when pressure is low (Alters Afferent Feedback Response)

Question 27

Muscle Afferents

Answer 27

Oppose Chemoreceptors, Baroreceptors, and Autoregulation (Afferent)

Question 28

4 types of muscle Afferents (only 2 cause Δ circulation)

Answer 28

Type III= Ergoreceptors (stretch sensitive); Type IV= Chemo & thermo sensitive

Question 29

Action

Answer 29

Afferently signal CVC; Cardioacceleratory: Increase HR & contractility Pressor center= Increase vasoconstriction

Question 30

Muscle Afferents, Mitchell paper (1983)

Answer 30

Type IV: Low exercise intensity (inactive/no stimuli); High exercise intensity (very active); VC in active muscle? (offset autoregulation) Explains Saltin (1988)!!!

Question 31

Autoregulation: not regulated by a BCS but still very important! (Self Governance)

Answer 31

Blood flow increased to meet metabolic demands of tissue (Major factor during exercise); Arterioles dilate in response to: O2 Tension, CO2 Tension, Nitric Oxide, Potassium, Adenosine, pH