LS4004 - Human Physiology- Cardiovascular Recap

What is systemic circulation?

carries oxygenated blood to the body

What is pulmonary circulation?

deoxygenated blood flow between heart and lungs

FLOW OF BLOOD THROUGH THE HEART. starting at Body [10 steps]

BODY, vena cava, right atrium, right ventricle, pulonarty artery, LUNGS, pulmonary vein, left atrium, left ventricle, aorta, body

What stops the back flow of blood?

valves

valve between the right atrium and right ventricle

tricuspid valve

valve between left atrium and left ventricle

bicuspid valve

valve between left ventricle and aorta

aortic valve

Valve between pulmonary artery and right ventricle

pulmonary valve

What are arteries?

Blood vessels that carry oxygenated blood away from the heart

What are veins?

Blood vessels that carry deoxygenated blood back to the heart

What vessels supply blood to the heart?

coronary arteries

What are the autorythmic cells?

non-contractile cell in the heart, pacemakers of the heart.

How are action potentials generated in autorythmic cells?

Automatically, without need for stimulus.

What is the SAN?

sinoatrial node (pacemaker of the heart)

How does the heart beat? [2]

1) SAN generated impulse (automatically, as it is autorythmic)
2) impulse travels through heart, exciting contractile heart muscle and it contracts briefly
this is a heartbeat.

ELECTRICAL CONDUCTION PATHWAY OF THE HEART IN 5 LONG STEPS

1) Impulse generated at the SAAN at the top of the heart
2) Impulse spreads (through internodal tracts) and excites the atria. Impulse reaches the AV node located at the bottom of the atria.
3) Atria Contraction occurs. after a 500 millisecond delay, the impulse travel from the AV node down the Bundle of His, along the interventricular septum.
4) The impulse travel through the lefthand right Bundle of His , which branch off into Purkinje Fibres which on the heart wall surrounding the ventricles. The ventricles are excited.
5) The excited ventricles contract.

Why is there a 500millisecond delay between the impulse entering and leaving the AV node?

The impulse causes contraction in both the atria and the ventricles. The Atria and ventricles cannot contract at at the same time.

What is preload?

the degree of stretch on the heart before it contracts

The electrical conduction pathway of the heart in STEP 1

Impulse generated at the SAN

The electrical conduction pathway of the heart in STEP 2

Impulse spreads via interniodal tracts through the atria to the AVN. The atria are excited.

The electrical conduction pathway of the heart in STEP3

Atraqil contraction occurs. There is a 100msc delay. Then the impulse spreads down the bundle of His.

The electrical conduction pathway of the heart in STEP4

The impulse travels through the left and right bundle which branch off into purkinje2 fibres