8.5 The Heart Flashcards Preview

8. Transport In Animals > 8.5 The Heart > Flashcards

Flashcards in 8.5 The Heart Deck (24)
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What is teh heart made of

Cardiac muscle


What supplies the heart with oxygenated blood

Coronary arteries


What is the heart surrounded with

Inelastic pericardinal membranes
They help prevent the heart from over-distending with blood


Where does deoxygenated blood enter the heart

The right atrium from the upper body in the superior vena cave and the lower body in the inferior vena cava
At a relatively low pressure


How does deoxygenated blood flow through into the right ventricle

Slight pressure builds up until the atrioventricular valve (tricuspid valve) opens


What happens to the deoxygenated blood when the right ventricle fully contracts

Goes through the semilunar valves into the pulmonary artery which transports it to the capillary beds of the lungs


Where does oxygenated blood Enter the heart

Left atrium from the pulmonary vein


What opens when pressure builds up in the left atrium

Teh bicuspid valve
Letting blood flow into teh left ventricle


What happens when the left ventricle contracts with oxygenated blood

The oxygenated blood is pumped through the semilunar valves into the aorta and around the body
The tricuspid valve closes


What is teh cardiac cycle

The events in a single heartbeat


What happens in diastole

The Heart relaxes
Atria and then the ventricles fill with blood
Volume and pressure of the blood in the heart build as the heart fills


What happens in systole

Atria contract closely followed by ventricles contracting
Pressure inside the heart increases dramatically and blood is forced out of the right side of teh heart to the lungs and from the left side to the main body circulation
Blood pressure in arteries are at maximum


What can the sounds of teh heartbeat be heard by

A stethoscope


What do the 2 heart sounds come from

1- blood is forced against the atrio-ventricular valves as ventricles contract
2- as a backflip is blood closes the semilunar valves in the aorta


What does myogenic mean

The heart has its own intrinsic rhythm at around 60 beats per min


What is the pathway of electrical excitation in the heart

Begins at sink-atrial node
Atria contract
Electrical impulse is picked up by the AVN
AVN imposes a slight delay before stimulating the bundle of his which penetrate through the septum if the heart
Bundle of his splits into 2 branches and the wave goes to the apex (bottom) is the heart
Then the purkinje fibres spread out through the walls of the ventricles


What is in place to prevent teh excitation passing directly to the ventricles

A layer of non-conducting tissue


What is the bundle of his

A bundle of connecting tissues made up of fibres


What is an electrocardiogram

The recording of electrical activity of the heart
It measures tiny electrical differences in you skin which result from the electrical activity of teh heart


How does an electrocardiogram work

Electrodes are stuck painlessly for clean skin to get teh good contacts
Single from each electrode is fed into a machine producing a ECG


What is tachycardia

Heartbeat is very rapid over 100bpm


What is Bradycardia

When the heart rate slows down to below 60bpm


What is ectopic heartbeat

Extra heartbeats that are out of the normal rhythm


What is atrial fibrillation

Example of arrhythmia- abnormal rhythm of teh heart
Rapid elevtrucal impulses are generated in teh atria however they don’t contract properly in the ventricles so as a result it doesn’t pump efficiently