Unit 2.6
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What is the pathway of blood through the body?
The heart pumps oxygenated blood through the body to where every tissue uses that oxygen to function your cells. This causes deoxygenated blood to be passed to the heart which makes its way to the lung to get filtered into oxygenated blood which will be passed back through the heart to pass to the rest of the body to oxygenate.
What is the largest artery in the body and what does it do?
The aorta carries oxygenated blood away from the left ventricle to the body.
What is the largest vein in the body and what does it do?
The vena cava carries deoxygenated blood to the heart.
What does the pulmonary artery do?
Carries deoxygenated blood away from the right ventricle to the lungs
What did the pulmonary vein do?
Returns oxygenated blood from the lungs to the heart.
How to figure out cardiac output?
CO = SV X HR
What are the 3 stages of cardiac cycle?
• Atrial and Ventricular Diastole • Atrial Systole • Ventricular Systole
What happens during diastole?
The heart is relaxed and blood returning from the atria flows into the ventricles. Atrial pressure exceeds that in the ventricles and AV valves are open whilst higher pressure in the arteries close the SL valves
What happens during atrial systole?
2 atria contract at the same time. This transfers the remainder of blood through open AV valves to the ventricles. Ventricles fill with blood and SL valves stay closed
What happens during ventricular systole?
Ventricles contract and the AV valves close and blood is pumped out through the SL valves to the aorta and pulmonary artery.
Overall, what valves are opened and closed during diastole, atrial systole and ventricular systole?
Diastole: AV valves are open SL valves are closed A. Systole: AV valves are open SL valves are closed V. Systole: AV valves are closed SL valves are open
What is pacemaker also known as and what does it do?
The sino-atrial node, (SAN), is located in the wall of the right atrium and sets the rate at which the heart contracts.
What is the process if the heartbeat produced by the SAN?
Electrical impulses generated by the contracting cells in the SAN are passed through the left and right atria (causing the atria to contract - systole) to the AVN.
Where is the AVN located?
Near the centre of the heart in the lower walls of the right atrium.
What happens to the electrical impulse during systole?
It is conducted to the cells in the ventricles.
What part of the body regulates the rate of SAN and what ways do the autonomic nervous system work?
The medulla in the brain regulates the rate of SAN. The autonomic nervous system works in antagonistic ways.
Give account the sympathetic nervous system.
The sympathetic nervous system increases heart rate and releases noradrenaline which can be activated by fear or stress causing a fight or flight response.
Give account the parasympathetic nervous system.
The parasympathetic nervous system slows the heart rate and releases acetylcholine which can be activated by rest and digest.
What do the letter stand for in an electrocardiogram?
P = The wave of electrical impulses spreading over the atria from the SAN (atrial systole). QRS = The electrical impulses through the ventricles (ventricular systole) T = The electrical recovery of the ventricles at the end of ventricular systole
What is blood pressure generated by?
The contraction of the ventricles.
When is blood pressure highest and lowest?
Highest during ventricular systole. Lowest during diastole.
What is blood pressure measured in and what can it be measured by?
It is measured in mmHg (millimetres mercury) and can be measured using a sphygmomanometer.
High blood pressure above what is known as hypertension?
140/90