The heart Flashcards
What does the AV valve do
The atrioventricular valve prevents back flow of blood from the ventricles to the atrium
What does the SL valves do
The semi lunar valves prevent back flow of blood into ventricles
What are the sounds you hear through the stethoscope
Opening and closing of AV and SL valves
How do you calculate Cardiac output
Heart rate x Stroke volume
What is the cardiac cycle
Refers to the pattern of systole and diastole shown by the heart in one complete heartbeat
What is the SAN
Situated in the wall of the right atrium, the Sinoatrial node sends out electrical impulses to direct the heart beat and ensure both atria contract simultaneously.
Where do the SANs electrical impulses go after the atria contract
They go to the Atrioventricular node in the centre of the heart.
What does the AVN do
the atrioventricular node sends out impulses that travel down fibres in the central wall of the heart and then up through the walls of the ventricles, causing ventricle systole.
How can the SAN respond to different situations and regulate the heartbeat
It is connected to the medulla, which regulates the rate of the SAN through the antagonistic action of the autonomic nervous system
What do sympathetic nerves do
Release noradrenaline which increases heart rate
What do parasympathetic nerves do
Release acetylcholine which decrease heartrate
What is detected by an électrocardiogramme
Currents caused by the SAN and AVN impulses
How is blood pressure generated
Through the contraction of the ventricles
Where is blood pressure the highest
Aorta and Pulmonary Artery
How do you measure blood pressure
Sphygmomanometer
What does 120/80mmHg mean
Pressure during ventricular systole / pressure at ventricular diastole
What does a sphygmomanometer do
It’s inflatable cuff stops blood flow. As it deflates gradually is detects a pulse (systolic pressure). Diastolic pressure is detected when the blood flows freely through the artery and no pulse is detected
What is hypertension
High blood pressure - The prolonged elevation of blood pressure when at rest
What is hypertension a major risk factor for
Many diseases such as coronary heart disease and strokes
What reading is hyper tension determined by
Anything greater than 140/90
What is hypertension caused by
- Overweight
- Lack of exercise
- Diet rich in saturated fats
- Overconsumption of salt
- Excessive alcohol intake
- Impact of continuous stres
