Download Outline the control of the heart beat in terms of myogenic muscle

+
Outline the control of the heart
beat in terms of myogenic
muscle contraction, the role of
the pacemaker, nerves, the
medulla of the brain and
adrenalin (epinephrine).
+
+
The heart is is myogenic
The cardiac muscle in
the heart can contract
and relax without
stimulation from the
nervous system
+
+
+
Three stages of cardiac cycle

Atrial Systole (contraction)


Ventricular Systole (contraction).


The sinoatrial node (SAN) contracts and transmits electrical
impulses throughout the atria, which both contract, pumping
blood into the ventricles.
The electrical impulse passes to the ventricles via the
atrioventricular node (AVN)
Diastole (relaxed)

The atria and the ventricles relax, while the atria fill with blood.
The semilunar valves in the arteries close as the arterial blood
falls back against them.
+
How the heart functions
+
+
Key terms

Sinoatrial node (SAN)

Atrio-ventricular node (AVN)

Atrial systole

Ventricular systole

Diastole
+
Pacemaker
A pacemaker replaces the sinus node when your heart beats to fast,
having a heart failure or a heart block which is a delay in the electrical
conduction.
+
Pacemaker inside
the heart.
+

Almost all pacemakers are implanted to
treat slow heart beating, which is called
“bradycardia”, possible reason could
be :

sick sinus syndrom

Possible reason for
implanting a
pacemaker
a medical procedure to treat an
arrhythmia called atrial fibrillation.

heart medicines, such as beta blockers.
the heart usually beats about 50 to 70
times each minute, and the heart rate
may increase 2- to 3-fold during stress
or exercise. If the heart beats too
slowly, the brain and body do not get
enough blood flow and a variety of
symptoms may result.

faint or have other symptoms of a slow
heartbeat

heart muscle problems that cause
electrical signals to travel too slowly
through your heart muscle.

Sympathetic nerve secretes
adrenaline (also known as
“epinephrine”)



The sympathetic nervous
system belongs to autonomic
nervous system along with
parasympathetic nervous
system.
which carries messages from
the brain to the pacemaker
telling the pacemaker to speed
up the beating of the heart.
vagus nerve

tells it to slow it down, and
Adrenalin, carried to the
pacemaker by the bloodstream
tells it to speed up the beating
of the heart.
Nerves and
Hormones

Nerves and hormones
can transmit messages
to the pacemaker
+
Medulla and heart beat
modification
parasympathetic
sympathetic
+
Adrenaline and heart rate
+
Adrenaline