Download Cardiac System

Physiology
AS PE





17 lessons to go before the exam!
That means 17 pieces of homework
Each will be a template to complete on a
particular topic
There will be exam questions on the topic for
the first 5-10 minutes of each lesson (sit in
the seat allocated for progress test)
Feedback will be given on a weekly basis
Your success is in your own hands!!!


Identify key components of the cardiac
muscle
Explain the cardiac cycle and conduction
system of the heart



The heart – the muscular pump that
pushes blood to the working muscles
The blood vessels (venules, veins, arteries,
arterioles and capillaries) – the routes by
which the blood travels to and through the
tissues, and back to the heart
The blood – in which materials are
carried to and from the tissues

What are the functions of the CV system?
1.
Delivery of Oxygen & Nutrients
2.
Removal of waste products – CO2
3.
Thermoregulation (Vasodilation and
Vasoconstriction)
Vasodilation – blood vessels swell or dilate – widen
– allows blood flow
Vasoconstriction – narrowing (constriction) of blood
vessels – blood slowed / blocked



Situated to the left of centre of the chest
Muscular pump whose purpose is to drive the
blood into and through the arteries, to deliver it
to the tissues and working muscles
Is myogenic – generates its own impulses

Considered as two separate pumps – (Double
Circulatory System)

Two chambers on the right, and two chambers on
the left side

Septum separates the two sides of the heart
allowing them to function correctly



RIGHT side – DEOXYGENATED blood to the
LUNGS through PULMONARY circulation
LEFT side – pumps OXYGENATED blood to all
other TISSUES in the body via SYSTEMIC
circulation
RIGHT & LEFT side fill SIMULTANEOUSLY
AORTA
SUPERIOR
VENA CAVA
PULMONARY
ARTERY
PULMONARY
VALVE/
SEMILUNAR
PULMONARY
VEINS
RIGHT
ATRIUM
LEFT ATRIUM
BICUSPID
VALVE/MITRAL
VALVE
TRICUSPID
VALVE
INFERIOR
VENA CAVA
LEFT
VENTRICLE
RIGHT
VENTRICLE
SEPTUM
AORTIC
VALVE/
SEMILUNAR




The process of cardiac contraction and blood
transportation through the heart
Sequence of events that take place during
one complete heartbeat
Diastole phase – filling of the heart (heart
relaxing)
Systole phase – emptying of the blood into
the arterial system (heart contracting)
At rest:
1. Atrial Diastole
2. Atrial Systole
3. Ventricular Diastole
4. Ventricular Systole
Each cycle takes approximately 0.8s (0.5s diastolic
phase / 0.3s systolic phase) and occurs on average
72 times per minute
Is this likely to change with increased heart rate
during exercise?


Watch the below video and complete the
worksheet provided
http://mypeexam.org/topic/cardiac-cycle-2/
Lungs
Pulmonary
artery
Pulmonary circulation
Pulmonary
vein
Left
heart
pump
Right
heart
pump
Systemic circulation
Aorta
Vena cava
Body
(non-lung tissues)
•ATRIAL DIASTOLE
STAGE 1
•Blood enters the atriums as the atrial walls relax
•The tricuspid and bicuspid valves are closed
•ATRIAL SYSTOLE
STAGE 2
•Blood is forced through the tricuspid and bicuspid valves as the atrial walls
contract
•VENTRICULAR DIASTOLE
STAGE 3
•The ventricular walls are relaxed as the blood enters and fills the ventricles.
•The pulmonary and aortic valves are closed
•VENTRICULAR SYSTOLE
STAGE 4
•Blood is forced through the pulmonary and aortic valves as the ventricles
contract
Conducting System Of The Heart - YouTube
Impulse initiated at
sino-atrial node
(right atrial wall)
Enters the Bundle of
His
This Atrioventricular
bundle travels along the
ventricular septum with
branches both left and
right into the ventricles
Rate that SA node
emits impulses
determines heart rate
AV node acts as a
distributor and passes
the impulse from the
atria to the ventricles
(0.13s delay)
These then subdivide
into Purkinje fibres
Once emitted, impulse
spreads to interconnecting fibres of the
atrium – excitation
causes atria to contract
Then passes to
another specialised
mass of cells –
Atrioventricular node
Purkinje fibres transmit
the impulse through the
ventricles, allowing all
parts to contract at the
same time
1.
What is the name of the vein that brings blood back from the body?
2.
What is the name of the valve that lies between the left atrium and left ventricle
3.
What is the name of the muscular wall that lies separates the left and right side of the
heart?
4.
What does the term ‘myogenic’ mean?
5.
How long does diastole last?
6.
What is referred to as the pacemaker of the heart?
7.
In the aortic arch what receptor might you find which detects changes in PH?
8.
Why is the heart known as a duel pump?
9.
Why is the left ventricle more muscular than the right ventricle?
10.
What is the name given to the fibres that the impulse travels down from the AV node?
1.
Vena cava
2.
Bicuspid valve
3.
Septum
4.
Generates its own impulse
5.
0.5 seconds
6.
SA Node
7.
Chemoreceptors
8.
The right side and left side pump at the same time
9.
It has to pump the blood further
10.
Bundle of his
By the end of this lesson you will:
Recap the cardiac cycle and
conduction system of the heart
 Explain cardiac output, stroke volume,
heart rate and the relationship
between them


Complete the Exam Questions provided

You have 8 minutes to do this

Get ready for the Kahoot quiz!
HR=The number of times the
heart beats per minute
(number of complete cardiac
cycles)



Average HR Value= 72bpm
Bradycardia=Lowering of RHR
due to training (normally said
to be below 60bpm)
Pulse Rate= Refers to the
measuring of your HR. This is
done at either radial or carotid
artery
RHR= 32-34bpm
Heart rate can increase with vigorous
activity to around 200 bpm
depending on age
 Controlled by the sino-atrial node
(SAN) – pacemaker of the heart





What do you think the resting heart rate of the
below athletes is?
Chris Froome
29bpm
Mo Farah
33bpm
Andy Murray
37bpm
Provide a reason to support each of your answers



The amount of blood pumped by the left
ventricle/ heart per beat / contraction
During exercise increases are progressive
until they gradually level off at a higher level
until exercise has ended
Due to the sharp increase in blood flow when
exercising, a greater oxygen supply is
available to the skeletal muscles
-SV increases with increases in work rate
-SV usually plateaus at 40-60% of VO2max – due to shorter
diastolic phase due to increased HR near maximal
Resting SV
Sub-max
Maximal
Trained
80-110ml
160-200ml
160-200ml
Untrained
60-80ml
100-120ml
100-120ml
What are the reasons for these changes?

SV is determined by a number of factors………..
1.
Venous return- Volume of blood returning to
the heart via the veins
2.
3.
Elasticity of the cardiac fibres- the more the
fibres stretch during diastole the greater the
force of contraction (Starling’s Law)
Contractility of the cardiac tissue- the greater
the contractility of the tissue, the greater the
force of contraction (can increase with training)
– increased ejection fraction

The mechanism where an increased venous
return leads to greater diastolic filling,
resulting in a stronger ventricular contraction
and therefore an increase in stroke volume


Q=The amount of
blood pumped out of
the left ventricle per
minute (SV X HR)
Measured in L/Min
•
•
Resting value is 5.0 L/min
Increases with increasing exercise intensity
up to 20 to 40 L/min

Calculate the Cardiac Output for the below
subjects at rest:
Subject
Stroke Volume
Heart Rate
Untrained
70ml
72bpm
Trained
85ml
60bpm

How might the cardiac output for each
individual change during exercise?
Resting Q
Sub-max
Maximal
Trained
5L/min
15-20L/min
30-40L/min
Untrained
5L/min
10-15L/min
20-30L/min
What are the reasons for these changes?

Explain how it is possible for a trained
performer and an untrained performer to
have the same cardiac output for a given
workload.
(2 marks)




Different sized hearts / hypertrophy – trained
bigger.
Different stroke volumes – trained bigger.
Different heart rates – untrained higher.
Can only occur at sub maximal workloads;
At higher workloads untrained will not be
able to increase their heart
rate sufficiently;
Different physiques / size / mass – untrained
bigger.


Complete the table provided on Balanced Diet
We will then have exam questions next week
at the start of the lesson


In 3’s, you are to rotate around the four
different stations
You have 7 minutes to complete the activity
provided at each station
By the end of this lesson you will:


Explain neural and hormonal control of the
heart
Recap the cardiac system

Complete the exam questions provided

You have 12 minutes

Slides from other PP

Watch the video provided
http://mypeexam.org/topic/control-of-heartrate-2/
During a game of football, a player’s heart rate
will vary.
Explain how changes in the acidity of the blood
cause the heart rate to increase during a game
of football.
(4 marks)

Blood’s acidity increases / pH lowers.
Eq = more hydrogen ions / H+.

Caused by more carbon dioxide being produced.

This is detected by chemoreceptors.

Nerve messages are sent to the medulla (oblongata) /
cardiac (control) centre.
needs more / increased.
needs idea of detect.
Needs idea of communication with medulla.
CCC too vague .

Sympathetic nervous impulses are sent.
To the Sino-Atrio node / SAN/SA node.
Decrease in parasympathetic / vagus nerve impulses.
Needs idea of decrease / less vagus impulses.
[4]





Changes to heart rate are regulated
by the Cardiac control centre (CCC)
which is located in the medulla
oblongata.
The CCC is made up of 2
components:
Sympathetic nervous systemincreases HR
Parasympathetic nervous systemSlows HR
Both the sympathetic and
parasympathetic systems act upon
the SA node

Sympathetic Nervous System
◦ Increases heart activity – releases adrenaline and
noradrenaline
◦ Adrenaline – increases strength of ventricular wall
contraction
◦ Noradrenaline – aids the spread of impulse throughout the
heart, increasing heart rate
◦ Constricts blood vessels and raises blood pressure
◦ Physical activity or stress

Parasympathetic Nervous System
 Decreases heart rate – releases acetylcholine which slows
the spread of impulses
 Mainly controls heart rate at rest

A number of sensory receptors in the body send
information to the CCC:
1.
Mechanoreceptors-Detect changes in the
muscle
2.
Proprioceptors- Detect changes in the joints
3.
Chemoreceptors- Detect changes in PH
4.
Baroreceptors- Detect changes in pressure
(stretch receptors)
1
2
3
4
5
•Increase in C02 levels in the blood, increase in muscle
activity and increased pressure within the vena cava
•Detected by receptors(chemo, baro, proprio, mechano)
•Messages sent to the CCC in the medulla oblongata
•Messages is then sent to the SA node down the sympathetic
nerve
•HR and SV increases
1
2
3
4
5
•Exercise stops thus levels within the body return to normal
(i.e. CO2 levels drop)
•Detected by receptors (chemo,baro,proprio,mechano)
•Messages sent to the CCC in the medulla oblongata
•Messages is then sent to the SA node down the vagus nerve
•HR and SV decrease

The feeling you get before an important competition (the
‘butterflies’) is largely due to the hormone adrenaline.

Adrenaline increases your HR when you feel nervous and is
responsible for the ‘anticipatory response’

Adrenaline is released by the adrenal glands into the blood
in times of stress.

Adrenaline forms part of the sympathetic nervous system
and stimulates the SA node to increase HR. The release also
causes an increase in BP and an increase in blood glucose
levels

Noradrenaline= The hormone responsible for transmitting
nerve impulses

Acetylcholine=Hormone released by the parasympathetic
nerves which cause a decrease in HR




The phenomenon whereby heart rate ‘drifts’
upwards over time despite the performer
working at a constant rate
Occurs in warmer environments – linked to
the sweating response and associated with
redistribution of blood to the skin
This reduces the volume of blood returning
to the heart – reduces stroke volume
Heart rate has to increase to compensate for
this and to maintain cardiac output
1.
2.
Revise for a Progress Test next week –
Cardiac System
Complete the table provided