Transcript Review- Pathway of blood flow through the

Review- Pathway of blood flow through the
Blood from upper body
Deoxygenated blood from rest
of body to right atrium via
superior and inferior vena cava
 right atrium  right
ventricle  pulmonary artery
 lung where blood picks up O2
 left atrium via pulmonary
veins  left ventricle 
oxygenated blood left heart via
aorta to rest of the body
Blood from lower body
https://www.youtube.com/watch?v=KSbbDnbSEyM
Heart Trivia- Whiteboard activity
1. Label AD in the diagram below.
2. Which kind of blood
(deoxygenated/oxygenated?) that entering:
a. superior vena cava
b. pulmonary vein
c. pulmonary artery
d. aorta
3. Where does the blood come from before
entering the superior vena cava?
4. Where does the blood come from before
entering the inferior vena cava?
5. Where does the blood go to after leaving
the pulmonary artery?
6. The part receives blood from lung is:
a. left ventricle
c. left atrium
b. right atrium
d. septum
Tissues of the Heart
• The heart is
surrounded
by twolayered
membrane
called the
pericardium
- Epithelial tissue called endocardium, a smooth
lining inside the chambers
- Muscle tissue called myocardium, that provides
the propulsive force
Endocardium of atrium 
end = endothelial cell nuclei
Endo = endocardium
Myo = myocardium
Low power view of ventricle epicardium 
ad = adipose tissue
bv = blood vessel
nv = nerve
Myo = myocardium
Image s from http://courseweb.edteched.uottawa.ca/medicinehistology/English/Cardiovascular/HistologyHeart.htm#Fig 03
The Heartbeat
Cardiac cycle
= contractions and relaxations of heart muscles in
a complete heartbeat
Takes ~0.8 s
4 Valves
•flaps of connective
tissue
•prevent backflow
Atrioventricular (AV) valves
-are tricuspid valve made of 3 flaps and bicuspid (mitral) valve
made of 2 flaps
- Prevents backflow into atria when ventricles contract “lub”
Semilunar valves (both pulmonary and aortic valves; half-moon
shape)
prevent backflow into ventricles while they relax “dub”
Blood flow through valves: https://www.youtube.com/watch?v=rguztY8aqpk
Heart sound: “Lub-dub, lub-dub”
•Heart sounds are caused by the closing of valves
“Lub”
“Dub”
recoil of blood
recoil of blood
against closed AV against closed
valves
semilunar valves
Heart murmur:
defective valves
causing hissing sound
when blood squirts
backward through
valves
Lub-dub with Bill Nye: https://www.youtube.com/watch?v=riDPxasIz_I
How the heart contracts
How the heart contracts:
Sinoatrial (SA) node:
• Pacemaker, in the wall of right
atrium
• Sends out electrical signal
causing two atria to contract
simultaneously
Atrioventricular (AV) node
• transmits signal through
specialized fibres called bundle
of His and Purkinje fibres
•Purkinje fibres initiate almost simultaneous
contraction of all cells of the right and left
ventricles
https://www.youtube.com/watch?v=bwBM2Pa1LA8 with Bill Nye. Watch all
Electrocardiograph:
records electrical impulses by a beating heart
• P wave = atrial contractions
• QRS wave = ventricular contractions
• T wave = ventricle recovers
The “LUB” “DUB” of Our Hearts!
“lub”
“dub”
LUB
1
2
3
DUB
4
 the ventricles relax and the
semilunar valves close to
produce the second heart
sound (“DUB”).
 The relaxation of the
ventricles is followed by
the next firing of the SA
node for the next
heartbeat.
5
MRI- imaging tool for the heart
Heartbeat in real time https://www.youtube.com/watch?v=G4dFVeP9Vdo
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Blood Pressure
• Blood pressure= force exerted on vessels’ walls
as blood flows through them
• Pulses = evidence of artery under pressure due
to heart’s contraction
A digital sphymomanometer
measuring blood pressure
1. Inflate the cuff to close off flow to brachial artery
2. Listening to pulse, slowly release air until pulse is heard
and read the pressure – Systolic (i.e. pressure when the
ventricles contract)
3. Slowly release air until no pulse is heard and then read the
pressure – Diastolic (i.e. The pressure when the ventricles
relax; heart is at rest)
4. Healthy = 120/80 (units = mmHg)
https://www.youtube.com/watch?v=u6saTO8_o2g
Factors affecting Blood pressure
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Diameter of blood vessels
Volume of blood
Physical activity
Temperature
Body position
Age (blood pressure usually increases with age)
Stress level
Diet
Drinking too much alcohol
Medication etc.
Hypertension (high blood pressure)
 Too much Na+ in diet  causes H2O
to enter blood by osmosis 
increases blood volume  increases
blood pressure
 High blood pressure reading: above
140/90 mmHg
 Stiffer arteries make heart work
harder
 Arteries may rupture leading to
stroke, heart attack, kidney damage
etc.
Resource link: https://www.hypertension.ca/en/
Diagnosis https://www.youtube.com/watch?v=IGyeNtZZnrk
Bypass surgery: https://www.youtube.com/watch?v=7PpidBmoA4c
(@6min)
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Heart Bypass surgery
Atherosclerosis = Hardening of the arteries
Plaque (fat, cholesterol, Ca etc) built up in the artery
leading to stroke, heart attack, death
Balloon angioplasty
https://www.youtube.com/watch?v=RwWDOZ9oTP8
Face your partner: name as many songs with
“Heart” in their titles as you can