Download Starter Qs

B – The Cardiovascular System
1. The structure and function of arteries,
capillaries and veins
2. The structure and function of the heart
3. Pathology of cardio vascular disease
(CVD)
4. Blood glucose levels and obesity
KA 6: The structure and function
of the heart
REVISION:
Structure
of the
heart
(A)
Cardiac function
and cardiac
output
2.6 Key
Topics
(B) Cardiac
cycle
(D) Blood
Pressure
(C)
The structure and
function of cardiac
conducting system
KA 6c: Learning Outcomes
• Give another name for the pacemaker
• Describe the action of the SAN on the cardiac muscle cells,
including how this stimulates the AVN
• Identify SAN and AVN locations in a diagram
• State the role of an ECG
• Interpret ECG graphs in order to calculate heart rate
• State that the heart beat can be regulated by both nervous and
hormonal control
• State the role of medulla and the ANS
• Name the 2 nerves that can release hormones
• State the names of these 2 hormones and describe the effect
they have on the heart beat
Cardiac Conducting System
• The events of the
cardiac cycle are
brought about by
the activity of the
heart’s pacemaker,
or sino-atrial node
(SAN)
• It is located in the
wall of the right
atrium
Cardiac Conducting System
• The SAN is a small
region of specialised
tissues that contains
auto-rhythmic cells.
• These cells initiate
electrical impulses
that make the
cardiac muscle cells
contract at a certain
rate.
Cardiac Conducting System
• The timing of cardiac
cells contracting is
controlled by the impulse
from the SAN:
– Spreading through the
atria and
– then travelling to the
atrio-ventricular node
(AVN) and
– then through the
ventricles.
• These impulses generate
currents that can be
detected by an
electrocardiogram (ECG).
• P wave
• QRS complex
• T wave
ECGs
This electrocardiogram (ECG) shows one
cardiac cycle
ECGs
An ECG measures the electrical
changes that take place in the
heart.
• P wave – the wave of electrical
impulses spreading over the atria
from the SAN
• Q-R-S complex – the electrical
impulses through the ventricles
• T wave – the electrical recovery
of the ventricles at the end of
ventricular systole.
The person’s heart beat is: ______ bpm
KA 6c: Learning Outcomes
• Give another name for the pacemaker
• Describe the action of the SAN on the cardiac muscle cells,
including how this stimulates the AVN
• Identify SAN and AVN locations in a diagram
• State the role of an ECG
• Interpret ECG graphs in order to calculate heart rate
• State that the heart beat can be regulated by both nervous and
hormonal control
• State the role of medulla and the ANS
• Name the 2 nerves that can release hormones
• State the names of these 2 hormones and describe the effect
they have on the heart beat
What do you remember?
THINK/PAIR/SHARE – 2 minutes!
•
•
•
•
•
What are 3 main parts of the brain?
What do they do?
The brain is part of which body system?
What do nerves do?
What do hormones do?
Nervous System
Central NS
Brain
Peripheral NS
Spinal cord
Somatic NS
Autonomic NS
Sympathetic
Parasympathetic
Nervous System
Central NS
Brain
Spinal cord
Peripheral NS
Somatic NS
Autonomic NS
Sympathetic
nerve
Norepinephrine
Control centre
Para sympathetic nerve
Acetylcholine
Impulses can be sent along both of
these nerves to the heart. The heart
rate depends on which system exerts
a greater influence over the heart.
Tasks!
1. Read page 168, from the title
‘regulation’ onwards
2. Stick in your diagram and label it using
page 168 of the textbook
3. Write the title: The conducting
system of the heart & how it is
controlled
4. Complete the missing words exercise
and stick it in!
Wordbank!
•
•
•
•
•
Acetylcholine
Antagonistic
Atrium
Autonomic
AVN
• Contract
• Diastole
• Impulses
• Medulla
• Parasympathetic
• Sympathetic
• Speeds up
• Slows down
• Ventricles
• Ventricular systole
• The conducting system of the heart is controlled by the
autonomic
_________
nervous system
parasympathetic
• It is made up of the sympathetic and ___________systems.
antagonistic
These two systems are _________in
action
Speeds up
• The sympathetic nerve _________the
heart rate and
Slows down
parasympathetic nerve _________the
heart rate
medulla
• Impulses originate in the control centres in the _________
• The hormone nor-adrenaline (nor-epinephrine) is released by
sympathetic
_________accelerator
nerves, whereas the hormone
_________is
released by the slowing parasympathetic nerves.
acetylcholine
atrium
• The pacemaker or SAN is located in the right _________
impulses
• Once stimulated, the SAN starts producing _________and
contracts
contract
• These impulses cause the atria to _________
(atrial systole)
AVN
• This then stimulates the _________,
which is found at the
junction between the atria and ventricles
• The impulse from the AVN is carried by conducting nerves, which
ventricles
spread out over the _________.
• This causes the contraction of ventricles
diastole
Ventricular systole
(_________________),
followed by relaxation (____________)
Think!
• Why does your heart rate increase
during exercise?
Hormonal Regulation of SAN
• If stressed or during
periods of exercise, the
sympathetic nervous
system acts on the
adrenal glands, causing
the release of adrenalin
into the blood stream.
• Upon reaching the SAN in
the heart, the adrenaline
causes the SAN to
generate cardiac impulses
at a higher rate,
therefore bringing about
an increase in heart rate!
Re-cap!
• http://www.austincc.edu/apreview/Nurs
ingAnimations/cardiac_cycle.swf
• Don’t worry about advanced language:
– Pulmonary valve / aortic valve = SL valves
– Depolarisation = contraction
– Repolarisation = relaxation
– Further details on P QRS T graph
KA 6c: Learning Outcomes
• Give another name for the pacemaker
• Describe the action of the SAN on the cardiac muscle cells,
including how this stimulates the AVN
• Identify SAN and AVN locations in a diagram
• State the role of an ECG
• Interpret ECG graphs in order to calculate heart rate
• State that the heart beat can be regulated by both nervous and
hormonal control
• State the role of medulla and the ANS
• Name the 2 nerves that can release hormones
• State the names of these 2 hormones and describe the effect
they have on the heart beat