Unit 2.6 - The Structure And Function Of Heart Flashcards
What does the medulla regulate?
The rate of the sino-atrial node (SAN) through the antagonistic action of the autonomic nervous system (ANS)
Describe cardiac input
Cardiac input is the volume of blood pumped through each ventricle per minutes
Cardiac output is determined by heart rate and stroke volume
The left and right ventricle is pump the same volume of blood through the aorta and pulmonary artery
Explain the cardiac cycle
During diastole, Blood returning to the atria flows through the ventricles
Atrial systole transfers the remainder of the blood through the atrioventricular valves to the ventricles
Ventricular systole closes the AV valves and pumps the blood through the semilunar valves to the aorta and pulmonary artery
In diastole the higher pressure in the artistes closes the SL valves
What sets the rate at which the heart contracts?
The auto rhythmic cells of this Sino atrial node or pacemaker, located in the wall of the right atrium
What is responsible for heart sounds? And what are they heard with?
The opening and closing of the AV and SL valves are responsible for heart sounds
Heard with a stethoscope
Talk about the control of contraction and timing by cells of the SEN and transmission to the AVN
The timing of cardiac muscle cell contraction is controlled by impulses from the essay in spreading through the atria causing atrial systole.
They then travel to the atrioventricular node located in the centre of the heart
Impulses from the EV in travel down favours in the central wall of the heart and then up through the walls of the ventricles, causing ventricle systole
What can an electrocardiogram detect?
Currents generated by impulses in the heart
What should the interpretation of electrocardiograms involve (ECG)
Calculation of heart rate
Linking of the waves to atrial systole, ventricular systole and diastole
What does a sympathetic and parameter release?
Sympathetic nerve releases noradrenaline which increases heart rate
Parasympathetic nerve releases acetylcholine which decreases the heart
How does blood pressure change in the aorta during the cardiac cycle ?
- BP increases during ventricular systole
* BP decreases during diastole
Describe the measurement of blood pressure using a sphygmomanometer
- An inflatable cuff stops blood flow, in the artery and deflated gradually
- The blood starts to flow (detected by a pulse)
- The blood flows freely through the artery and pulse is not detected at diastolic pressure
What’s the typical blood pressure reading for a young adult?
120/80 mmHg
What is hypertension?
It means high blood pressure and is a major risk factor for many diseases including coronary heart disease
