Regulation Of The Heart Rate Flashcards
Which part of the heart contracts first?
Atrium
How is the heart a dual pump?
The left and right sides of the heart pump blood separately, but simultaneously, into the systemic and pulmonary circuits.
Cardiac contraction is triggered by…
…depolarization of CM that arises from the SAN
What is the normal heart rate
60 to 80 bpm
When is bradycardia physiologically normal?
- At sleep
- In trained athletes
When is tachycardia physiologically normal?
- In children
- Excitement
- Exercise
Agents that mimic PNS and SNS
PNS - Propanolol
SNS - Atropine
Agents that’s going to mimic the action or effects of the SN are referred to as
Catecholamines
What is the Intrinsic HR?
Seen when after the blockage of sympathetic and parasympathetic NS. It is 100bts/min
Factors responsible for heart rate regulation
BBHNCRV
Baroreceptor Bainbridge reflex Higher Centres Neural Chemoreceptor Respiration Ventricular Receptor
What controls the CVN?
Medulla oblongata
Steps in PNS neural regulation
- CVN cells controlled by medulla synapse with postganglionic on epicardium surface near SAN and AVN
- Right goes to SAN, left to AVN
- Effect = Reduction
The effect of the SNS In increasing the heart rate is a gradual process. True or false?
True
Does the hypothalamus increase or reduce heart rate?
It leads to an alteration in the heart rate, depending on which part of it is stimulated
What are the higher centers of the brain?
Frontal lobe of the brain
The cerebral cortex
The thalamus
Hypothalamus
The baroreceptors are located in…
…the Aortic Arch and Carotid sinuses
How do the baroreceptors cause changes in the heart rate?
They elicit changes in the heart rates due to acute changes in arterial blood pressure
What is the relationship between the arterial blood pressure and heart rate?
They are inversely proportional to one another
How does the Bainbridge reflex work?
Increase in blood volume or infusion of saline evokes the Bainbridge reflex, increasing the HR, magnitude of which depends on the prevailing HR.
What else is evoked by the Bainbridge reflex?
The baroreflex which antagonizes its action.
The actual change in HR depends on…
…the antagonistic effects of the baroreceptor reflex
Effect of Bainbridge reflex on heart rate?
Increases HR. Will be low if blood volume is increased and baroreflex is greater then Bainbridge
Atrial receptors are found in…
…the right atria wall
What is dysrythmia?
An alteration in the rhythm of the heartbeat
