http://www.youtube.com/watch?v=0Vn5AJ_Mjfs&NR=1
http://www.youtube.com/watch?v=m50596VvDPg&feature=related
UNIT K:
HEART STRUCTURE & FUNCTION
(Ch. 13, pp. 228-233)
K1. Identify & give functions for the following:
• Left and right atria
•
Left and right ventricles
•
Coronary arteries and veins
•
Anterior and posterior vena cava
•
Aorta
•
Pulmonary arteries and veins
•
Pulmonary trunk
•
Atrioventricular valves
•
Chordae tendinaea
•
Semi-lunar valves
•
Septum
K2. Describe the location and functions of
the SA node, AV node, and Purkinje fibers
K3. Describe the autonomic regulation of
the heartbeat by the nervous system
K4. Relate factors that affect and regulate
blood pressure to hypertension and
hypotension
K5. Demonstrate the measurement of blood
pressure
K6. Distinguish between systolic and
diastolic pressure
_____ Aorta
_____ Aortic valve
_____ Atrioventricular (AV) valves
_____ Atrium
_____ Autonomic nervous system
_____ AV node
_____ Blood pressure
_____ Brachial artery
_____ Bundle of His
_____ Chordae tendineae
_____ Constrict
_____ Coronary arteries
_____ Coronary veins
_____ Dilate
_____ Hypertension
_____ Hypotension
_____ Hypothalamus
_____ Inferior Vena Cava
_____ Medulla oblongata
_____ Pacemaker
_____ Pulmonary artery
_____ Pulmonary circuit
_____ Pulmonary trunk
_____ Pulmonary valve
_____ Pulmonary vein
_____ Purkinje fibres
_____ SA node
_____ Semi-lunar valve
_____ Septum
_____ Superior Vena Cava
_____ Systemic circuit
_____ Vagus nerve
_____ Ventricle
Amazing Heart Facts
• Put your hand on your heart. Where is it?
• Hold out your hand and make a fist.
size of heart: child = 1 fist; adult = 2 fists!
• Your heart beats about 100,000 times in one day and
about 35 million times in a year.
• During an average lifetime, the human heart
will beat more than 2.5 billion times.
•Even at rest, the muscles of the heart work twice as
hard as the leg muscles of a person sprinting
• In one day, the blood travels a total of 19,000
km. That's 4 times the distance across
CANADA from coast to coast.
•When you are resting, it takes 35-40
seconds for the blood to move through
your body. What about when you are
exercising?
approximately 10 seconds
•How much does your heart weigh?
only 2/3 of a pound!
• Give a tennis ball a good, hard squeeze.
You're using about the same amount of force
your heart uses to pump blood out to the body
1• Transports oxygen from the
lungs to body to be used
• Transports carbon dioxide
and hydrogen ions to the
lungs to be removed
2
3• Transports nutrients from
the small intestine to tissues
4 • Fights infections
5
• Transports water from the
digestive system to the
body and lungs
6• Carries waste products
(ie: urea) to kidneys for
removal in urine
7 • Distributes body heat
from internal source to
skin (to get rid of it)
8 • Seals wounds by forming
blood clots
9 • Transports hormones
around the body
10•
Maintains pH in tissues
(acts as a buffer with HHb)
11
Regulates fluid levels in
tissues (with Lymphatic
system)
The human heart has 4 well developed chambers
Right Atrium
Left Atrium
Right Ventricle
Left Ventricle
The right side
of the heart
pumps deO2
blood to the
lungs.
PULMONARY
The left side
of the heart
pumps O2
blood to the
body
SYSTEMIC
Left Atrium
Right Atrium
Receives
deoxygenated
blood from the
body via the
anterior &
posterior vena
cava.
Receives
oxygenated
blood from the
lungs via the
pulmonary veins
Tricuspid
Valve
1. Separate the
atria from the
ventricles.
2. They open
when the atria
contract.
3. They prevent the
blood from going
backwards when the
ventricles contract.
Bicuspid
Valve
Bicuspid
Valve
Tendon-like
pieces of
tissue
They keep
the AV
valves from
inverting
when the
ventricles
contract
They hold &
support the
chordae
tendinae
Can’t open
properly
Open
Closed
Normal Heart
Valves
Can’t close
properly
Heart Murmur
• When the right atrium contracts, it pushes the blood
through the tricuspid valve and into the right ventricle.
• When the RIGHT
VENTRICLE contracts, BP
forces the TRICUSPID
valve to close.
Right
Ventricle
• The BP forces
PULMONARY VALVE
open & the blood moves
into the PULMONARY
TRUNK.
The PULMONARY
ARTERIES take the deO2
blood to the lungs.
The CO2 is
removed from
the blood and is
replaced with O2.
The PULMONARY
VEINS take the O2
blood to the
heart.
The protein HEMOGLOBIN
binds the O2 tightly and
carries it to the body cells
as OXYHEMOGLOBIN!
A muscular wall that
separates the right side
of the heart from the left
side.
Keeps the deO2 blood
from mixing with the O2
blood
Some
people
are born
with a
hole in
their
septum
• When the left atrium contracts, it pushes the blood
through the bicuspid valve and into the left ventricle.
• When the LEFT
VENTRICLE contracts,
the BICUSPID VALVE is
forced closed.
• Blood is forced through
the AORTIC VALVE and
enters the AORTA.
• The left ventricle has a THICKER
muscle layer. WHY?
Left
Ventricle
•To the head
Aortic Arch
•To the arms &
lungs
•Coronary
Artery: to
the heart
Dorsal Aorta
•To the
lower body
The aorta takes O2 blood to the body.
The first branches of the aorta take the blood to the
coronary arteries.
Takes blood into the heart muscle itself. The coronary
veins return the deO2 blood to the vena cava  right atrium.
Superior Vena Cava
These are the BIGGEST
VEINS!
They bring the deO2
blood back to the heart
so that it can be
pumped to the lungs.
Inferior Vena Cava
Aortic Arch
Superior vena cava
Pulmonary Trunk
Coronary artery
Right Atrium
Right Ventricle
Inferior Vena Cava
Coronary Vein
Left Ventricle
Aortic Arch
Superior
Vena Cava
Right Pulmonary
Artery
Pulmonary
Trunk
Right Pulmonary
Veins
Pulmonary
(semi-lunar)
Valve
Tricuspid
(AV) Valve
Left Pulmonary
Artery
Left
Atrium
Left Pulmonary
Veins
Bicuspid (AV)
Valve
Right
Atrium
Left
Ventricle
Aortic (semilunar) Valve
Right
Ventricle
Inferior Vena Cava
Dorsal Aorta
• Heart cells
naturally beat slowly
if ATP is present
• If there was no
coordination, the
heart cells would all
beat randomly
Beating Human Heart:
http://www.youtube.com/watch?v=iX6HnUyzgQ0&feature=related
http://www.youtube.com/watch?v=GgPe3k-lK8c&feature=related
•There are two spots
of specialized tissue
in the heart.
• Both are located in
the right atrium.
• Nodal tissue is
unique: made of
specialized muscle
cells combined with
nerve cells.
• It has the ability to
contract independent
of other stimuli.
The SA NODE (sino-atrial)
SA NODE

This node is found
along the wall of the
right atrium chamber.

It fires on average, every
0.85 seconds (or 72 times
per minute).

It stimulates the
simultaneous contraction
of the atria.

It also sends a nerve
impulse along a nerve
trunk called the BUNDLE
OF HIS to the AV NODE
S
A
NODE
The SA node initiates the heartbeat and has been given
the nickname of the “PACEMAKER”
PACEMAKER
a small electronic
device that
stimulates the SA
node to fire
http://www.youtube.com/watch?v=CxJS0oEQeBQ
People with irregular heartbeats may have to have an
artificial pacemaker ‘inserted’.
The AV NODE (atrioventricular)
• In the right atrium close to the AV (tricuspid) valve
• When the AV node receives the impulse from the SA node,
it fires to initiate the contraction of the LARGE ventricles
A.V. NODE
PURKINJE FIBRES
• The AV node sends its
message through the P.F.,
which cause ventricles to
contract.
A
V
NODE
&
Purkinje fibres
• Atria beat
from top down,
then pause,
and the
ventricles beat
from bottom
up.
http://www.youtube.com/watch?v
=ew6Jp74vaN4
http://www.youtube.com/watch?v
=nK0_28q6WoM
FROG DISECTION http://www.youtube.com/watch?v=fO7lBX5CSxw
There are two parts to the contraction of the heart
The heart
beat is a
double
sound
(‘lub-
EKG
dub’).
An EKG (electrocardiogram) registers the voltage
changes across the surface of the heart as it beats.
The letters PQRST are the standard labels used to identify
the parts of the EKG.
P = the simultaneous
contraction of the atria
(caused by SA node)
QRS = the contraction of
the ventricles
(caused by AV node & purkinje
fibres)
T = the recovery of the
ventricles
(preparation for next
contraction)
KNOW THIS
DIAGRAM!
R
P
Q
S
KNOW THISDIAGRAM!!
T
Some Abnormal EKG’s
NORMAL
Tachycardia (a heart rate of over 100 beats/min)
Ventricular Fibrillation (uncoordinated ventricles)
Heart Block (failure to stimulate ventricles after atrial contraction)
• If the system really breaks down, the heart could go into
fibrillation. This is uncoordinated contractions of the
cardiac muscle.
• When this happens, the
pacemaker (SA NODE) will send
a strong shock through the
heart.
• Hopefully the heart muscle will
reset itself.
• This is known as defibrillation
• We also try to
do this
artificially when
people
are in cardiac
arrest!
The natural average resting heart rate is
72 beats per minute
The SA node is connected to the brain by the VAGUS
NERVE (cranial nerve #10).
The regulation of the heartbeat is under the influence of
the AUTONOMIC NERVOUS SYSTEM
(not under conscious control)
Sympathetic Nervous System: When the brain is not
receiving blood quickly enough, the brain will signal the SA node
(via the vagus nerve) to speed up its contraction. This will usually
occur in circumstances of FIGHT or FLIGHT. It will also occur
when the blood pressure is too low.
Parasympathetic Nervous System: this system will
reestablish the resting heart rate (~60-70 beats/minute) by
sending a message via the vagus nerve to slow the heart rate.
The part of the brain that governs the speed of the heart
rate is called the MEDULLA OBLONGATA
• It will speed up or slow down the heart rate when needed.
**Under normal circumstances, the heart controls itself.
Hardening of the arteries
Cholesterol in the blood can become deposited on the
inside walls of the arteries. This seems to happen faster
in people who:
•Smoke
•Have high blood pressure
•Eat high fat, high cholesterol foods, or, for other
reasons, have high cholesterol
•Are overweight
•Have a lot of tension and stress
•Do not exercise regularly
•Have diabetes and/or family members with a
history of atherosclerosis
Perform your own heart transplant:
http://www.pbs.org/wgbh/nova/eheart/transplantwave.html
Made from titanium metal and a special type of plastic.
A rechargeable internal battery
Normally an external power pack transmits power across the skin.
• Feel your pulse by placing two fingers
at pulse points on your neck or wrists.
Now count the beats for 15 seconds &
multiply by 4.
•As a kid, your resting pulse might range
from 90 to 120 beats per minute.
•As an adult, your pulse rate slows to an
average of 72 beats per minute.
What is YOUR pulse rate at rest? After exercise?
BLOOD PRESSURE: the ventricles pump approx. 70 mL
of blood each time they contract.
The pulse you feel is blood stopping and starting
as it moves through your arteries.
SYSTOLIC PRESSURE (systole): blood pressure when the
ventricles are contracting.
Blood is being forced through the arteries (approx. 120 mmHg)
DIASTOLIC PRESSURE (diastole): blood pressure as
ventricles are refilling.
This is between contractions, and the blood pressure is
less (appox 80 mmHg).
Blood pressure is normally measured along the
BRACHIAL ARTERY of the arm.
A reading of 120/80 mmHg is normal.
When you are younger, your
BP will be higher.
Example: 13-15 yrs. will be
136-144 over 86-92
HIGH BLOOD PRESSURE (ie: 150/100)
High blood pressure
sometimes goes
unnoticed until
complications set in.
Limit Alcohol
Eat less
salt
Be Active
Don’t
Smoke
Eat
Healthy
Lose
Weight
• High Blood Pressure puts constant strain on the
tissues (especially the capillary beds).
• May cause capillaries to burst
• If this happens in the brain = a stroke.
If it happens in the heart = heart attack!
• The longer you have high BP, the greater the potential for
tissue damage.
• Sometimes high BP is normal
(ie: when doing physical activity)
• However, the brain should return the BP to a normal,
lower level.
LOW BLOOD PRESSURE (ie: 100/60)
Low blood pressure is not particularly a good thing
either.
It can result from:
• Genetics
• Anemia *not enough iron*
• Dehydration *not enough water*
• Blood loss
• Shock
Proper kidney function can only be maintained if there
is sufficient pressure for filtration.
1. Vessel diameter:
bigger (dilate) = lower BP
smaller (constrict) = higher BP
Vasodilation to
lower BP
Vasoconstriction
to increase BP
2. Blood viscosity:
Thick blood (little water) = higher BP
Thin (lots of water) = lower BP
3. Total blood vessel length:
More fat = higher BP
Thinner = lower BP
More fat = more vessels = more resistance = increased BP
4. Vessel elasticity: affected by plaques (fatty deposits).
Elastic vessels = lower BP
Hardened vessels = high BP
ATHEROSCLEROSIS
(hardening of arteries = decreased elasticity).
5. Blood volume:
Sweat a lot = less
volume/water = lower BP
Eat lots of salt = more
volume/water stays in body =
higher BP
6. Cardiac output:
Heart rate increases = higher BP
Heart rate decreases = lower BP
7. Age: as you get older, there is a loss of elasticity in the
blood vessels.
Young = very elastic = low BP
Old = not elastic = high BP
8. Stress: constricts blood vessels which means
increased pressure to move the blood.
Stressed = constricted vessels
= Higher BP
Calm = normal vessels
= Lower BP
Heart Animations and Interactives
Animation: Your heart valves at work
Interactive: Label the heart
Interactive: Listen to the heart with a virtual
stethoscope
Interactive: Explore the structures of the heart and
trace the pathway of blood through the heart, lungs,
and body
Animation: See the flow of blood to and from the
exterior heart