Download Heart Anatomy The Heart Heart Membranes Layers of the Heart Wall

18 The Cardiovascular System: The Heart
The Heart
Part 1: Heart Anatomy
Heart Membranes
• pericardium - double-walled sac around the heart
fibrous (parietal) pericardium - tough and dense
protects the heart
anchors it to surrounding structures
prevents overfilling of the heart with blood
serous (visceral) pericardium - thin and slippery
reduces friction
• cone-shaped muscular organ about the size of
your fist
• weighs less than a pound
• 2/3 lies to the left of the body's midline
• apex (tip) tilted to the left
Layers of the Heart Wall
• epicardium - external heart
surface
often infiltrated with fat
• myocardium - heart muscle
responsible for muscle
contraction
arranged in spiral and
circular bundles
• endocardium - a simple
squamous epithelium lining
the inner surfaces of the heart
and blood vessels
VS.
18 The Cardiovascular System: The Heart
1 The heart is enclosed in a double
membrane sac called the ____.
Ping Pong Back &
Forth describing the
location, membranes,
and layers of the
heart.
2 Heart muscle is called the ____.
Chambers of the Heart
• 4 chambers
R and L atria on top of R
and L ventricles
• atria - small, thin-walled
chambers that receive blood
pumps blood "downstairs" to
ventricles
• ventricles - large, muscular
pumping chambers
pumps blood outside of heart
• R and L side of heart divided
by a septum
Atria
• right atrium - receives
deoxygenated blood
through superior vena
cava and inferior vena
cava
passes blood to right
ventricles through the
tricuspid valve
• left atrium - receives
oxygenated blood
through four pulmonary veins
pulmonary = lungs
2 veins from each lung
passes blood to left ventricles through bicuspid
(mitral) valve
Ventricles
• papillary muscles and chordea
tendinaea play a role in valve
function
• discharging chambers (pumps)
of the heart
walls thicker than atria
• right ventricle - pumps
deoxygenated blood through
pulmonary semilunar valve
and pulmonary trunk toward
the lungs
• left ventricle - pumps oxygenated blood through aortic
semilunar valve and aorta to all body parts
thicker wall than R ventricle
18 The Cardiovascular System: The Heart
Body
RA
Tricuspid
RV
Lungs
High Card Wins...Best 2 out of 3
LA
Bicuspid
LV
RIGHT
LEFT
low card...what do you know about the structure
of the heart so far?
High card...fill in the gaps.
4 The ___ side of the heart deals with
oxygenated blood.
3 MATA: The receiving chambers of the
are the
A
right atrium
B
right ventricle
C
left atrium
D
left ventricle
5 MATA: The tricuspid valve
A
is located on the right side of the
heart
B
separates atria from ventricle
C
touches oxygenated blood
D
is connected to the pulmonary
artery
18 The Cardiovascular System: The Heart
Pulmonary Circulation
Double Pump
• R side of heart handles oxygen
poor blood ONLY
pulmonary circuit
R heart
lungs
L heart
• L side of heart handles oxygen
rich blood ONLY
systemic circulation
L heart
body
R heart
harder work = bigger, stronger
structures
• circulates blood to lungs
• R atrium
R ventricle
pulmonary arteries
pulmonary arterioles
pulmonary capillaries
CO2 and O2 exchanged
pulmonary venules
pulmonary veins
L atrium
• blood travels in 2 distinct loops
double pump
picks up O2 from lungs
drops off O2 to body cells
Systemic Circulation
•
•
•
•
systemic = body systems
circulates blood to body
aorta - largest artery
superior/inferior vena cava largest veins
superior - collects blood from
head, chest, arms
inferior - collects blood from
lower body
• L ventricles
aorta
major
body regions
veins
superior/inferior vena cava
nonwinner...pulmonary circuit
NOSE
GOES
Winner...
systemic
circuit
18 The Cardiovascular System: The Heart
Path of Blood
6 The ____ circuit carries oxygenated
blood to body and returns
deoxygenated blood to the right side of
the heart.
semilunar
bicuspid/AV
semilunar
AV
Coronary Circulation
• myocardial cells require a continual supply of
oxygenated blood
• supplied by the coronary arteries
branch off of aorta
• angina - chest pain
· blockage of coronary
blood vessels can cause
a myocardial infarction
(heart attack)
Work with your partner to put it all together...
chambers, valves, blood flow, layers, membranes...
7
Trace the path of blood through the
heart. (Enter as a number. Ex. 12345678)
1- Lungs
2- body
3- pulmonary SL Valve
4- vena cava
5- Left atrium
6- right atrium
7- bicuspid valve
8- aorta
18 The Cardiovascular System: The Heart
Cardiac Conduction System
• ability of cardiac muscle to depolarize and contract
is intrinsic
Part 2: Heart Physiology
does NOT depend on nervous system
composed of autorhythmic cells
1. pacemaker potential
SA NOde
2
3
1
2. depolarization
no stable resting potential
instead, Na+ channels are
opened after hyperpolarization
allowing potential to drift
toward threshold
threshold potential = -40mV
Ca channels open and Ca rushes into cells
2+
2+
3. repolarization
K channels open and K rushes out of cell
+
+
Electrical System
1. Sinoatrial (SA) node
pacemaker
determines heart rate
70-80 per minute
1
2. Atrioventricular (AV) node
4
impulse pauses about 0.1 sec to
allow atria to finish contracting
3
3. Atrioventricular (AV) bundle
5
electrical connection between
atria and ventricles
4. R and L bundle branches
5. Purkinje fibers
2
highly branched
responsible for ventricular contraction
4
Click for animation
In a healthy heart, it takes 0.22 sec from SA node
stimulation to end of ventricular depolarization!
Rock Master...Describe an action
potential at the SA Node.
Best 2 out of 3
18 The Cardiovascular System: The Heart
Nonwinner...Explain how an
electrical signal spreads through
the heart.
2
Trace the electrical signal through the
heart. (Ex. 12345)
1- AV Bundle
2- Bundle branches
3- AV NODE
4- Purkinje Fibers
1 What ion is responsible for pacemaker
potential?
A
sodium
B
potassium
C
calcium
Changing the Rhythm
• cardiac center located in the medulla oblongata
sympathetic nervous system speeds up heart rate
and force (cardioacceleratory center)
parasympathetic nervous system slow down heart
rate and force (cardioinhibitory center)
• factors that affect heart rate
anxiety/stress and activity speed
up rate
meditation, yoga, sleep slow down
rate
5- SA NODE
Electrocardiogram (ECG)
• aka electrokardiogram (EKG)
• recording of the electrical changes in the myocardium
• P wave - atrial depolarization
Arrhythmias
tachycardia
quickly followed by atrial contraction
• QRS complex - ventricular depolarization
quickly followed by ventricular contraction
atrial repolarization obscured by QRS complex
fibrillation
• T wave - ventricular repolarization
bradycardia
18 The Cardiovascular System: The Heart
together...Make sure you can label each part of
an EKG and explain what is happening electrically
in the heart.
4 MATA: Which letter(s) represent
ventricular depolarization?
3 Name this part of the EKG.
Heart Sounds
• associated with closing valves
• lub-dub, pause, lub-dub, pause, and so on
lub - AV valves (tricuspid and bicuspid) close
dub - SL valves (pulmonary and aortic) close
pause - heart resting between beats
A
B
C
D
E
Cardiac Cycle
• aka "heartbeat"
• mechanical actions of the heart
• each heartbeat (cycle) blood is forced out of
ventricles
• average adult pumps about 5 L/min
• stroke volume - volume of blood pumped by each
ventricle per heartbeat
• cardiac output - volume of blood pumped per
minute by the heart (both ventricles)
multiple stroke volume (mm) by heart rate (beats/min)
18 The Cardiovascular System: The Heart
Cardiac Cycle (cont.)
Cardiac Cycle
• systole - contraction of heart muscle
• diastole - relaxation of heart muscle
• steps
1. atria contract forcing blood into relaxed ventricles
(AV valves open, SL valves closed)
2. ventricles contract forcing blood into pulmonary
trunk and aorta (AV valves closed; SL valves open)
3. both atria and ventricles relax and atria begin to fill
passively with blood (all valves closed)
Putting It All Together
5 Heart sounds are caused by
A
electrical signals travelling the
conduction system
B
valves shutting
C
blood filling chambers
D
the heart contracting
18 The Cardiovascular System: The Heart
6 During diastole, the heart muscle relaxes
and fills passively with blood.
7 MATA: Stimulation from the AV node
A
causes the ventricles to contract
True
B
allows the atria to relax
False
C
depolarizes of the ventricles
D
causes AV valves to open