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The Heart and Blood Vessels

Unit -3 The Organism

Barry Heffernan

on 5 May 2014

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Transcript of The Heart and Blood Vessels

The pacemaker is also called the sino-atrial node (SA node) and is found in the right atrium
the pacemaker sends out electrical pulses
the pulses cause the atria to contract
the atrio-ventricular node is located at the junction of the atria and ventricles
when the pulse reaches the AV node it is strengthened and sent down the septum
the pulse causes the walls to contract
Smoking is bad for the heart because:
nicotine increases heart rate and raises blood pressure
carbon monoxide reduces the ability of the blood to carry oxygen
chemicals in smoke increase risk of clots
Diet may affect the heart:
Fat increases the chance of arteries blocking
too much salt increases blood pressure
being overweight increases blood pressure
Lifestyle and the heart-
Blood pressure is recorded by measuring the pressure needed to stop the flow of blood in the upper arm
normal blood pressure is 120/80mm of mercury
upper value is systolic pressure and lower value is diastolic pressure
high blood pressure is if the lower value is above 95
Blood pressure-
2) Blood is pumped into ventricles
atria contract - atrial systole
tricuspid and bicuspid valves are forced open
blood is pumped from the atria to the ventricles

3) Blood is pumped from the heart
ventricles contract - ventricular systole
tricuspid and bicuspid valves are forced shut
blood is pumped to the lungs and body
Diastole refers to when heart muscle is relaxed
Systole is when the heart is contracted
There are three stages in the cardiac cycle:
1) Blood enters the heart
blood enters the atria due to pressure from previous heart beat
Atria and ventricles are relaxed
all valves are closed
Stages of heartbeat
Portal system
A portal system is one in which the blood starts and ends in capillaries
The hepatic portal vein is an example of a portal system
The hepatic portal vein goes from the stomach and intestines to the liver
The heart is a double pump as one side pumps to the lungs and the other pumps blood around the rest of the body
Advantages of double circulation:
oxygen rich and oxygen poor blood are separated
blood pressure is high enough to reach all parts of the body
Double circulation
The bicuspid and tricuspid valves prevent blood passing back into the atria
The semi lunar valves prevent blood being sucked back into the heart from the aorta and pulmonary artery
The walls of the atria are thin as blood is only passed into the ventricles
The wall of the left ventricle is very thick as it pumps blood all around the body
Valves and muscular walls
Oxygenated blood enters the left atrium through the pulmonary veins
left atrium pumps blood through the bicuspid valve to the left ventricle
left ventricle pumps the blood to the rest of the body through the aorta
Structure of the heart
Small, much branched blood vessels
have thin walls
materials pass in and out easily between the blood and cells of the body
Carry blood to the heart
have low pressure
have thin walls
have valves
have large lumens
carry oxygen-poor blood (except pulomnary vein)
The three types of blood vessels are:

Arteries and veins have three similar layers in their walls:
inelastic protein called collagen
muscles and elastic fibres
inner layer called endothelium
Blood vessels
In open circulatory systems
the heart pumps blood into vessels that are open ended

In closed circulatory systems
the blood remains in a continuous system of blood vessels
blood moves around the body faster
allows alterations in blood flow to organs
Open and closed blood systems
The heart and blood vessels
(H)Control of heartbeat -
Deoxygenated blood enters the right atrium of the heart through the vena cava:
right atrium pumps blood to the right ventricle through the tricuspid valve
right ventricle pumps blood out the pulmonary artery to the lungs
Blood flow through the heart
Carry blood away from the heart
have high blood pressure
have thick walls
do not have valves
have narrow lumens
carry oxygen-rich blood (except pulmonary artery)
A pulse is the alternate expansion and contraction of the arteries
The pulse can be felt most easily in the wrist or the neck
The average adult pulse rate is 72 beats per minute
Learning Check
What are the two different types of circulatory system?
name an organism in which you would find each
Name three different types of blood vessels
Give two properties of each of the blood vessels you named
Learning Check
What side of the heart deals with deoxygenated blood
Which chamber of the heart is the Aorta connected to?
Which chamber of the heart is the pulmonary artery connected to?
Learning Check
What is a portal system?
What is meant by pulse?
What is the average human pulse rate?
Name two lifestyle choices that can effect your heart rate.
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