8.5 The Heart Flashcards Preview

Biology Module 3 > 8.5 The Heart > Flashcards

Flashcards in 8.5 The Heart Deck (21):
1

Name the different vessels and their functions

Aorta : oxygenated blood to the body
Vena Cava : de oxygenated blood to the heart
Pulmonary artery : deoxygenated blood to the lungs
Pulmonary vein : oxygenated blood to the heart

2

Which side of the heart is thinner? Why?

To make sure the delicate lung tissue isn’t damaged.

3

What is the function of tendinous cords?

To make sure the valves are not turned inside out by the pressure exerted when the ventricles contract

4

What do valves do? How do they work?

They stop blood flowing the wrong way

They one open one way.

If there is more pressure behind a valve, they are forced open.

If there is more pressure in-front of the valve, it’s forced shut.

5

Where are the semi-lunar valves?

Link the ventricles to the pulmonary artery and aorta

6

Where are the atrioventricular valves?

In between the atria and ventricles.

7

Describe and explain the cardiac cycle ( just for notes, other cards for revision)

Atria contract ( ventricles relax )
This decreases their volume and increases pressure
Blood pushed into ventricles through atrioventricular valves
Slight increase in ventricular pressure and volume as they receive the blood

Ventricles contract ( atria relax )
This decreases their volume and increases pressure
This pressure forces the atrioventricular valve close
This also opens the semi-lunar valves
Blood is forced into the pulmonary artery and aorta

Both atria and ventricles relax
Semi lunar valves close
Atria fills with blood and increases pressure
Ventricles continue to relax and have decreased pressure
AV valve opens and blood flows passively into ventricles

Atria contracts

8

What happens after the atria contract ?

This decreases their volume and increases pressure
Blood pushed into ventricles through atrioventricular valves
Slight increase in ventricular pressure and volume as they receive the blood

9

What happens after the ventricles contract?

This decreases their volume and increases pressure
This pressure forces the atrioventricular valve close
This also opens the semi-lunar valves
Blood is forced into the pulmonary artery and aorta

10

What happens after both the atria and ventricles relax?

Semi lunar valves close
Atria fills with blood and increases pressure
Ventricles continue to relax and have decreased pressure
AV valve opens and blood flows passively into ventricles

11

Where is the sino-atrial node and atria ventricular node located?

The right atrium

12

Define myogenic

Can contract and relax without receiving signals from nerves

13

Describe how the SAN and AVN work to make the heart contract

SAN sends out waves of electrical activity to atrial walls

This causes both atria to contract at the same time

Layer of non-conducting collagen tissue prevents waves of electrical activity behind passed directly to ventricles

Instead it is transferred to the AVN

AVN passes it onto bundle of His ( after slight delay to make sure ventricles contract after atria have emptied )

bundle of His conducts waves to Purkyne tissue

Purkyne tissue carries waves into walls of both ventricles causing them to both contract at the same time from the bottom up

14

What is the bundle of His?

A group of musicale fibres

15

What do electrocardiographs record?

When the heart contracts, it depolarises ( loses electrical charge )

When the heart relaxes, it repolarises ( regains charge )

ECG records these changes

16

Describe and explain the different peaks on an ECG graph

The P wave is caused by contraction ( depolarisation ) of the atria

Main peak with dips either side ( QRS complex ) - caused by contraction ( depolarisation ) of the ventricles

T wave is caused by relaxation ( repolarisation) of ventricles

17

What does the height of the waves on an ECG show?

How much electrical charge is passing through the heart - a bigger wave means more electrical charge

Bigger wave = stronger contraction

18

What is tachycardia?

Heartbeat is too fast

At rest , heart isn’t pumping blood efficiently

19

What is bradycardia?

Heartbeat is too slow

20

What is an ectopic heartbeat?

The 5th heartbeat ( an extra heartbeat )

Caused by an earlier contraction of the atria

Can also be caused by early contraction of the ventricles

21

What is fibrillation?

An irregular heartbeat

The atria / ventricles completely lose their rhythm and stop contracting properly

Can result in symptoms ranging from chest pain and fainting to lack of pulse and death