Cardiovascular System and Heart Rate Regulation

This assignment discusses the cardiovascular system and its regulation factors. It explains how the sympathetic nervous system (SNS) and parasympathetic nervous system (PNS) control heart rate, and how stroke volume is affected by preload, contractility, and afterload. The assignment also touches on the impact of blood pressure fluctuations, exercise, and chemoreceptors on heart rate regulation.

Cardiovascular system

TABLE OF CONTENTS
TASK 6............................................................................................................................................1
A. Defining the terms..................................................................................................................1
B. Influence of concentration of blood gases and changes in BP on these factors.....................1
REFERENCES................................................................................................................................3

TASK 6
A. Defining the terms
Heart rate
There are two specified branches in the nervous system that controls the heart rate. The
two branches are named as sympathetic nervous system (SNS) and the parasympathetic nervous
system (PNS). Nerves also play an important role as spinal ganglionic nerves and vagal nerves
are known to mediate the decrease the rate of heart beat. Hormones, norepinephrine and
epinephrine are being released by the sympathetic nervous system and are widely known to as
making accelerations and increase in the heart beat rate of a human body (Attias and Ruchaya,
2017). On the other side the parasympathetic nervous system is said to release the hormone,
acetylcholine which decreases the heart rate of an individual.
Stroke volume
Stroke volume is considered as the overall volume of the amount of total blood that is
being pumped by the left ventricle on every single beat. The index of stroke volume can be
evaluated on the basis of three factors and these are preload, contractility and the after load. The
combination of heart beat rate along with the stroke volume are said to produce the cardiac
output. With each single beat, a specific rate of blood is being released (Mancia and Grassi,
2014). There are various factors that directly or indirectly has some influence on the heart rate
and stroke volume as well such as hormonal factors, the diet of person, medications involved etc.
B. Influence of concentration of blood gases and changes in BP on these factors
There are some factors that can have an impact on the heart beat rate and stroke volume.
In case of any fluctuations in the blood pressure of a person, there are chances that the heart beat
rate might get double but it cannot be considered as a risk factor. Also, it is an obvious fact that
when a person exercises, it however increases the rate of exhaustion of carbon dioxide in the
body. There are chemoreceptors as well that comprises of aortic acid along with the carotid
bodies (Koenig and Thayer, 2014). The aortic is responsible for detecting any new change that
has been done in the blood oxygen but not in case of pH whereas carotid is responsible for
detecting changes in blood, pH and in carbon dioxide as well. So, by means of these
chemoreceptors, the level of carbon dioxide gets detected. Then a signal is sent directly to the
1

brain via the efferent nerve and the same signal is then sent back to the heart, due to which the
result occurs as an increased heart rate.
2

REFERENCES
Books and Journals
Koenig, J. and Thayer, J. F., 2014. Body mass index is related to autonomic nervous system
activity as measured by heart rate variability—a replication using short term
measurements. The journal of nutrition, health & aging. 18(3). pp.300-302.
Attias, J. and Ruchaya, P., 2017. Altitude exposure and increased heart rate: the role of the
parasympathetic nervous system. The Journal of physiology. 595(14). pp.4589-4590.
Mancia, G. and Grassi, G., 2014. The autonomic nervous system and hypertension. Circulation
research. 114(11). pp.1804-1814.
3