Contains details of nerve and hormone function relating to the heart. Diagram and pthway

1. Control of heart rate in humans
KEYWORDS:
Learning outcomes:
·Cell metabolism,
·myogenic, ·outline the hormonal and
·pacemaker, nervous mechanisms involved
·sino-atrial node in the control of heart rate in
(SAN), humans.
·atrio-ventricular node
(AVN),
·medulla oblongata,
·cardiovascular Sympathetic nervous
centre, system
·sympathetic, Parasympathetic nervous
·parasympathetic, system
·bradycardia, accelerator nerve
·tachycardia, vagus nerve
·baroreceptors, pressure, chemo, stretch
·adrenalin, and thermo receptors
·noradrenalin

2. ·In what kinds of situations does cell activity
increase?
·during exercise, stress, etc
·What are the three ways the heart responds in
these situations?
·increased heart rate, increased strength of
contraction, increased stroke volume
·What are the benefits of this response?
·oxygen and glucose reaches respiring cells more
quickly, carbon dioxide and other waste removed
more quickly

3. The heart adapts to meet the requirements
of your cells in different situations

4. ·create a poster entitled 'How does the brain control the
heart?'
·you can use the laptop, textbook has loads of
information...consider the questions below- must be
finished today!
·What features of the heart influence heart rate?
·What part of the brain influences heart rate? How?
·Which hormone influences heart rate? How?

5. Co-ordinating Control:
At rest, the SAN controls heart
rate. It has a set frequency (60-
80 action potentials per minute)
This can be modified/controlled
by
1. The cardiovascular centre in
the medulla: Produce a summary diagram
to show what controls heart
·Three receptor groups send rate and how.
inputs to the cardiovascular
centre
·Two nerves link the
cardiovascular centre with the
SAN
2. The hormone adrenaline

6. Plenary Question:
What are the consequences of an
increase in CO2 concentration in the
blood?

7. Plenary Question:
What are the consequences of an increase in CO2
concentration in the blood?
·decreased pH, due to increase in HCO3- / H+ ;
·detected by chemoreceptos in carotid arteries aorta
and brain
·impulses sent from receptors to cardiovascular
centre
·cardiovascular sends increased frequency of
impulses along accelerator nerve to SAN
·increased frquency of action potentials from SAN
·heart rate increases
·increased stroke volume / stronger contraction ;
·more / faster, removal of carbon dioxide ;
·(blood carbon dioxide falls to) norm / set point ;
·negative feedback / homeostasis ;
buffering effect of haemoglobin,
·

8. ·What features of the heart
influence heart rate? the muscle is
myogenic, the SAN (pacemaker)
generates an action potential
which travels through the AVN and
purkyne fibres
·What part of the brain influences
heart rate? the medulla oblongata
How? nerves from here affect the
frequency of contractions; action
potentials sent along the
accelerator nerve increase heart
rate, those sent along the vagus
nerve decrease heart rate

9. ·Which hormone influences heart rate? How?
adrenaline, specific receptors exist on heart
muscle cells, when adrenaline binds cAMP acts as
the second messenger to create an effect