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The Heart
Transporting O2 and other stuff
(The Circulatory System)
4 distinct circuits for the
flow of blood
Pulmonary Circulation –
heart to lungs and back
Systemic Circulation – heart
to entire body and back
Renal Circulation – blood
flow through kidneys
Hepatic-Portal Circulation –
blood flow through liver
and digestive system
Can you recognise all of
Can you relate what you see in
these structures? diagrams to what you see in real
life?
You must be able to recognise all the major features of the heart and
appreciate their relationships. A science picture from grade 5 - any mistakes?
The Heart
A.
Heart Facts
1.
Size of human fist
2.
Located in center of chest
under the sternum.
3.
Outside covered with a
protective sac called the
pericardium which helps
lubricate the surface of the
moving heart.
B.
Structure
1.
Has four chambers
R. atrium
L. atrium
R. ventricle
L. ventricle
2.
Divided into two sides by the septum.
Septum
3.
Each side has 2 chambers
a.
Atrium - thin walled on top
b.
Ventricle - thick walled on bottom
4.
The heart muscle is nourished by its
own series of coronary arteries,
capillaries and veins.
Coronary
artery
Coronary
vein
5.
The heart contains 4 valves that ensure
blood flows in one direction.
a.
Between the atria and ventricles are the
atrioventricular valves
Tricuspid
valve
Bicuspid
valve
b.
There are two semilunar valves at the
exit of the ventricles.
Pulmonary
valve
Aortic valve
6.
Blood flow summary
a. O2 poor and CO2 rich blood from the
body enters the R. atrium from the
vena cava
Superior
Vena cava
Posterior
Vena cava
b.
Blood pumped to the R. ventricle
through the tricuspid valve.
Tricuspid
valve
c.
R. ventricle pumps blood through
pulmonary valve to L and R pulmonary
arteries.
Pulmonary
valve
Pulmonary
arteries
d.
Blood travels to lung capillaries where O2
is picked up and CO2 dropped off.
e.
Blood enters the L. atrium through 4
pulmonary veins.
Pulmonary
veins
Pulmonary
veins
f.
Blood pumped into L. ventricle through
bicuspid valve.
Bicuspid valve
Bicuspid
valve
g.
Blood is pumped from the L. ventricle
through the aortic valve into the aorta.
aorta
Aorta
aortic valve
How Blood Flows:
The Heart
You must be able to follow the
path of blood flow through the
heart without any problem.
You must be able to follow the
path of blood flow through the
heart without any problem.
- The two atria work together to collect
blood (VEINS) and then pump it into
the ventricles.
- The two ventricles work together by
collecting blood from the atria and then
pumping it AWAY from the heart.
(ARTERIES)
You must be able to follow the
path of blood flow through the
heart without any problem.
- The two atria work together to collect
blood (VEINS) and then pump it into
the ventricles.
- The two ventricles work together by
collecting blood from the atria and then
pumping it AWAY from the heart.
(ARTERIES)
- a right heart pumping blood to
the lungs
- a left heart pumping blood
around the body
Two separate circuits
You must be able to follow the
path of blood flow through the
heart without any problem.
Blood flow
AFTER birth
Before birth, bypass
the lungs:
- ductus arteriosus
- foramen ovale
-‘best blood’ goes to
liver, heart and brain
- blood flows from
high to low pressure
Blood flow
BEFORE birth
C.
Heart Valves
1.
Ensure one way flow of blood
through the heart.
2.
AV valves are anchored with
cordae tendonae.
3.
Heart sounds are produced by
closing valves.
a.
Described as “lub dub”
b.
Lub = AV Valves closing during
contraction (systole)
c.
Dub = Semilunar valves closing
during relaxation (diastole)
D.
Measuring Heart Rate
1.
Pulse or heart rate = contractions per
minute.
2.
Your heart rate changes in response to:
a.
Heart
rate 1
Exercise – muscles demand food
and O2 and generate more waste.
b.
Heart
rate 2
Stress or excitement – body
perceives need for fight or flight.
c.
Chemicals – nicotine, caffeine
directly stimulate the nerves that
control the heart.
Coordination of the Beating
• Heart cells naturally beat
slowly if ATP is present
• If there was no coordination,
the heart cells would all beat
randomly (fibrillation)
• Coordinated beating occurs
because a group of cells (the
pacemaker cells) send nerve
impulses to the other cells
stimulating them to beat at the
right time
• Atria beat from top down,
pause, Ventricals beat from
bottom up
The heart muscle is self-stimulating
because of the action of the sinoatrial
node, a collection of nerves in the right
atrium.
The SA node acts as a pacemaker
and sends signals to the atria and
atrioventricular node in the
septum of the heart.
The AV node distributes the nerve
impulse via nerves of the Bundle of
His and then Purkinje fibres to the
ventricles.
The heart contracts from top to bottom;
atria, followed by ventricles.
Heart rate can be altered by two nerves
coming from the medulla oblongata of the
brain to the SA node.
i.
Vagus nerve – more impulses slows
heart rate. Part of the
parasympathetic nervous system.
ii.
Sympathetic Nerve – more impulses
increase heart rate. Part of the
sympathetic nervous system.
Heart rate can also be increased by the
release of epinephrine (adrenaline) by the
adrenal gland into the blood.
Assignment:
Create a valentine
Include
• Diagram of heart
• Structure of heart (labeled)
• Colour red for oxygenated and blue for
deoxygenated
• Direction of blood flow
• How the heart beats
• Catchy phrase describing a function of the heat