Download Heart rate regulation and control.

RECAP FROM THE PREVIOUS LESSON.
Describe how the conduction system
of the heart controls the cardiac
cycle. [4 marks].
Using the work you did for
homework, discuss the question in a
small group.
Learning Objectives...
1) To understand how the CCC affects
our heart rate.
2) To understand how exercise affects
the CCC.
Heart rate regulation and
control.
The heart is capable of
increasing or decreasing Q to
meet the demand for O2
made by the working
muscles.
How is the heart regulated to
meet these changes?
Cardiac control centre (CCC)
Located in the medulla Oblongata
of the brain.
The CCC is primarily responsible for
regulating the heart.
The CCC is controlled by the
autonomic nervous system
(ANS).
ANS
ANS means it is under involuntary
control and consists of:
Sympathetic nervous system =
increase HR (Via accelerator nerve)
Parasympathetic nervous system
= decrease HR (Via vagus nerve).
How does the CCC regulate
HR?
Each cardiac cycle is controlled by
the CCC.
The CCC initiates either the
sympathetic or parasympathetic
nervous system to stimulate the SA
node causing either….?
INCREASE
HR
CCC
SYMPATHETIC
NERVOUS SYSTEM
DECREASE
HR
PARASYMPATHETIC
NERVOUS SYSTEM
ACCELERATOR
NERVE
VAGUS NERVE
SA Node
What factors affect the activity
of the CCC???????
Neural control =
chemo/baroreceptors
Hormonal control = adrenalin.
Intrinsic control = venous return.
When we start to exercise neural
control starts working and…
 Proprio-receptors in muscles,
tendons and joints, inform CCC
that movement has increased.
Chemoreceptors located in aorta
and carotid arteries detect
decrease in blood pH due to
increase of lactic acid and CO2.
Baroreceptors detect increase in
blood pressure, aorta and carotid
arteries are sensitive to stretch
Exam question
Cardiac output is a determining factor
during endurance activities. Describe
how cardiac output is increased
during endurance activities. [4
marks].
1.Chemo/barorecetors detect.
2. Stimulate CCC
3. Initiates Sympathetic via accelerator.
4. Increased impulse at SA node.
5. Increased HR/SV = increased Q.