Transcript igcse_heart - Help for MYP 4 and 5 Students

MAKING SENSE OF
THE HEART
IGCSE Biology
2.3 Blood and Circulation
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Image © Depositphotos.com/[julos #4371007]
• Can you label a diagram of the human heart
and explain how it functions?
• How does heart rate change during exercise
and under the influence of adrenaline?
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Cardiac muscle – never gets tired
Pumps blood to BODY & LUNGS
Contracting (systole) and Relaxing (diastole).
Valves ensure blood flows in one direction
Left Atrium
Right Atrium
Right Ventricle
Left Ventricle
http://bryanbrandenburg.net/wikpedia-heart-3d/
The heart is a DOUBLE PUMP:
1st - blood is pumped to the lungs & returns to the heart,
2nd - blood is pumped to respiring muscles & back to the heart again.
1. Deoxygenated
blood is pumped
from the heart to the
lungs
4. The oxygen
leaves the blood to
be used for
respiration in the
body and the blood
goes back to the
heart
2. The blood
receives oxygen
and is pumped back
to the heart
3. The oxygenated
blood is then
pumped to the rest
of the body
Aorta
Pulmonary Artery
Vena Cava
Pulmonary Vein
http://bryanbrandenburg.net/wikpedia-heart-3d/
Coronary arteries
http://bryanbrandenburg.net/wikpedia-heart-3d/
Aorta
Pulmonary Artery
Vena Cava
Pulmonary Vein
Left Atrium
Right Atrium
Right Ventricle
Coronary arteries
Left Ventricle
http://bryanbrandenburg.net/wikpedia-heart-3d/
Chambers of the Heart
Left Atrium
Right Atrium
Left Ventricle
Right Ventricle
Aorta
Pulmonary Artery
Pulmonary Vein
Vena Cava
Semi-lunar valves
Bicuspid valve
Tricuspid valve
Semi-lunar valves
Bicuspid valve
Tricuspid valve
Aortic Semi-lunar valve
Aorta
Pulmonary Artery
Pulmonary Semilunar valve
Pulmonary Vein
Vena Cava
Left Atrium
Bicuspid valve
Right Atrium
Tricuspid valve
Left Ventricle
Right Ventricle
Pulmonary
semi lunar
valve
The Heart
Pulmonary artery
Vena Cava (vein from body
and head)
Right Atrium
Tricuspid valve
Right Ventricle
Septum
Aortic semi
lunar valve
Aorta (to heads and rest of body)
Pulmonary vein
Left Atrium
Bicuspid valve
Left Ventricle
Blood flow in the heart
• View my heart dissection and answer the
multiple choice questions:
http://ed.ted.com/on/IEZPxYXv
• Blood enters the atria.
• cannot pass into the ventricles because the
tricuspid and bicuspid valves are shut.
Deoxygenated
blood from body
Oxygenated blood
from lungs
• atria contract (systole).
• Increases blood pressure in atria – forces
valves to open
• Blood forced into the ventricles .
• ventricles contract.
• Forces the bicuspid and tricuspid valves to
close
• Blood cannot return to the atria.
• Ventricles continue to contract, which forces
open the semi-lunar valves.
• Blood is forced into the aorta and the
pulmonary artery.
• ventricles relax (diastole).
• The semi-lunar valves close.
• The cycle starts again as the atria start filling
with blood.
• The heart itself needs its own supply of blood.
• It gets this from the coronary arteries.
Coronary arteries
http://bryanbrandenburg.net/wikpedia-heart-3d/
• EXERCISE increases = RESPIRATION increases,
requiring an increase in OXYGEN
• Increased RESPIRATION = increased CO2
• Therefore, HEART RATE increases to speed up
deliver of OXYGEN to respiring cells (also to
remove extra CO2)
• Sensor in AORTA & CAROTID ARTERY (neck)
detect CO2 levels in blood
• Information flow:
accelerator
nerve
Heart
speeds up
sensor  medulla (brain)
deccelerator
nerve
Heart slows
down
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ADRENALINE hormone released when stressed
It prepares for physical activity
‘FIGHT or FLIGHT’ hormone
Adrenaline increased HEART RATE
Why is this important in certain situations?