heart Flashcards
1
Q
where is the atrio-ventricular valve
A
connecting the atrium and ventricle
2
Q
where is the semi-lunar valve
A
connecting the ventricle and the aorta/pulmonary artery
3
Q
what is the first ‘lub’ sound of the heart caused by
A
the atrioventricular valves closing
4
Q
what is the second ‘dub’ sound of the heart
A
semi-lunar valves closing
5
Q
first stage of the cardiac cycle
A
- ventricles relax
- atria contract
- volume decreases
- pressure increases
- pushes blood into ventricles through AV valves
- ventricular pressure increases
6
Q
second stage of the cardiac cycle
A
- atria relax
- ventricles contract
- decreasing volume
- increasing pressure
- pressure is higher in ventricles than atria, causing AV valve to shut
- pressure is higher in ventricles than aorta/pulmonary artery, causing semi-lunar valve to open
- blood is forced out into arteries
7
Q
third stage of the cardiac cycle
A
- ventricles and atria relax
- higher pressure in arteries than in ventricles causes SL valves to close
- higher pressure in veins than in atria forces blood into atria
- increases pressure in atria
- lower pressure in ventricles than atria so AV valves open and blood flows to ventricles passively
8
Q
why is the left side of the heart thicker
A
- has to produce sufficient force to move blood to the whole body and overcome resistance of aorta
9
Q
how to calculate cardiac output
A
heart rate(bpm) x stroke volume(blood volume pumped during each heartbeat cm3)
10
Q
diastole
A
- heart relaxes
- atria and ventricles fill with blood
- volume and pressure of blood in heart build up
11
Q
systole
A
- atria contract (atrial systole)
- then ventricles contract (ventricular systole)
- pressure increases dramatically
- blood is forced out the heart
- volume/pressure in heart are low at the end of systole
12
Q
myogenic
A
- cardiac muscle
- it can contract and relax without receiving signals from nerves
13
Q
rhythm of the heart
A
- wave of electrical excitation begins at sino-atrial node (right atrium wall)
- causes atria to contract
- layer of non-conductive collagen tissue prevents it spreading directly to ventricles
- waves transferred from SAN to atrioventricular node
- AVN imposes slight delay before stimulating bundle of His (conducting tissue made up of Purkyne fibres) which are in septum
- bundle of His splits into 2 branches conducting wave to the apex
- at the apex, Purkyne fibres spread out through both ventricle walls, causing them to contract (from bottom up)
14
Q
Tachycardia
A
- when heartbeat is very rapid
15
Q
Bradycardia
A
when heart beat slows down to below 60 bpm
16
Q
ectopic heartbeat
A
extra heartbeat out of normal rhythm
17
Q
atrial fibrillation
A
- rapid electrical impulses generated in atria
- contract very fast
