The Valves Of The Heart And Heartbeats Flashcards
(27 cards)
What do the valves of the heart do?
They control the flow of blood.
What are the two types of valves?
Atrioventicular valves and Semilunar valves.
What do atrioventricular valves do?
They separate the atria from ventricles.
What do corrdae tendinae do?
The attach to muscular projections from the walls of the ventricles and prevent the back flow of blood during ventricular contraction.
What do the semi lunar valves do?
They separate ventricles from vessels.
What can leaky valves cause?
They can cause regurgitation of blood.
What are heart murmurs?
They’re the whooshing or swishing sounds during the heartbeat cycle.
What are causes of heart murmurs?
Septal defects (holes in the septum)
Heart valve abnormalities (don’t allow enough blood through or don’t close properly)
Rheumatic fever
What is rheumatic fever?
Untreated strep throat, causes swelling and scarring of the valves which causes valves to narrow. This makes them harder to open and close properly, forcing the heart to work harder and can lead to congestive heart failure.
What part of the brain regulates heart rate?
The medulla oblongata.
What are the 2 pairs of nerves that act against to keep heart rate at an optimal level?
Accelerator nerves and vagus nerves
What do accelerator nerves do?
Increases the heart rate
What do vagus nerves do?
They decrease the heart rate.
Where do nerves terminate?
At the sinatrial node of the heart (also known as the pacemaker)
What’s the sinoatrial node responsible for?
Setting the hearts own inherent rhythm of contraction.
What does physical stimuli release?
Messages by the medulla oblongata causes the release of adrenaline
If blood pressures too high…
Causes the release of acetylcholine that slows the firing of the S.A node.
If the blood pressures too low…
Epinephrine is released and increases the firing of the S.A node.
What does nervous stimuli cause and why?
It causes heart rate to increase because the medulla oblongata sends out epinephrine.
What’s the first step involved in producing a heartbeat?
The SA node is stimulated.
What’s the second step involved in producing a heartbeat?
Wave of contraction of the atria.
What’s the third step involved in producing a heartbeat?
Stimulation of the atrioventicular node.
What’s the fourth step involved in producing a heart beat?
The AV node sends the message down the bundle of His to the apex of the heart.
What’s the fifth step involved in producing a heartbeat?
In the apex of the heart, Purkinjie fibres receive the message and initiate the contraction of the ventricles.
