Human circulatory system and the Heart Flashcards
(23 cards)
What is mass transport and what does it do
Involves transporting all substances in the same direction at speed
- usually via vessels and tubes
- Moves substances quickly from one exchange area to another
- Helps to maintain a diffusion gradient
What type of circulatory system do human have and what are the circuits
Double circulatory system involving blood passing through the heart twice in a circuit
- Pulmonary circuit (heart to lungs)
- systemic circuit (heart to body)
Also a closed system
What does a closed circulatory system do
what is blood contained in
It maintains the pressure
blood contained in vessels
What are the advantages of a closed circulatory system
- pressures can be different in the pulmonary and the systemic circuits (systemic needs more pressure)
- Different organs can receive different volumes of blood (blood can be redirected) depending on the situation e.g. digestion, exercise etc
What are the advantages of a double circulatory system
- No mixing of blood so an increased delivery of oxygen
- Different pressures allowed in pulmonary vs systemic systems
What are the chambers of the heart and what oxygen do they carry
- Deoxygenated blood
Right atrium and ventricle (left side on paper)
Left atrium and ventricle - Oxygenated blood
Left atrium and ventricle (right side on paper)
What are the vessels in the heart and what do they do
Vena cava - Deoxygenated blood into the right atrium
Pulmonary artery - Deoxygenated blood to the lungs
Pulmonary vein - Oxygenated blood to the left atrium
Aorta - Oxygenated blood around the body
What are the valves in the heart and where are they located
. Atrioventricular valves (AV valves) = Located between the atrium and ventricles
- tricuspid valves (right side)
- bicuspid valves (left side)
. Semi-lunar valves
- Aortic valves (bottom of aorta near top of left ventricle)
- Pulmonary valve (In the pulmonary artery between both sides of the heart)
What are Chordae tendinea and what do they do
Attach the valves to papillary muscles
- Muscles contract to open/close valves
- Prevent the inversion of valves
What structures are involved in electrical activity of the heart and where are they
-Sino-atrial node (SAN) = Located in the upper right atrium (initiates heart beat)
- Atrioventricular node (AVN) = Located in the lower right atrium
- Bundle of his = A bundle of nerve cells passing down between the ventricle
-Purkinjie fibres = Spread up the walls of the ventricles
What are the cardiac muscles and how do they contract
They are muscles in the heart
It contracts without stimulation and so is myogenic
What does the conary artery do in the heart and what happens if it becomes blocked and why does this happen
Conary artery carries blood to the cardiac muscles and runs across the front of the heart
Conary arteries become blocked and leads to conary heart disease
- Due to a fat build up restricting blood flow leading to a potential heart attack
How to you find the heart rate (Bpm)
Heart rate (bpm)=
60s / length of 1 beat (s)
What is the cardiac cycle
Sequence of contraction and relaxation of the heart chambers
What are the phases of the cardiac cycle and what happens in them
. Diastole - Blood enters through the vena cava and pulmonary vein.
- semi lunar valves are closed and AV valves are open
- Passive filling of the ventricles (80%)
. Atrial systole - Blood pumped from atria to ventricles
. Ventricular systole - Semi lunar valves open and AV valves close. Blood pumped through the aorta and pulmonary artery
How is the cardiac cycle controlled and explain
Controlled by nodes
- An electrical impulse is initiated by the SA node causing the atria to contract (atrial systole
- AV node delays the impulse before transmitting it to the ventricles so the atrium can be fully empty before the ventricles contract
- The bundle of his and purkinje fibres transmit the impulse across the ventricular walls
- The ventricles contracts (ventricular systole)
Why is pressure important in the heart and how is it created
- Blood moves from a high to low pressure down a pressure gradient
Contraction (systole) decreases the volume in the chamber so increases the pressure
Why are valves important regarding the pressure inside the heart
- A valve will open/close according to the pressure gradient
- Valves act as a one way door (chordae tendinea prevent inversion)
When are the AV valves closed and open
and when are the semi lunar valves opened and closed
. AV closed - Ventricle pressure>atrium pressure
. Semi lunar open - Ventricle pressure> aortic pressure
. Semi lunar closed - Aortic pressure> ventricle pressure
. AV open - Atrium pressure> ventricle pressure
In regards to pressure in the heart what happens during diastole
- Atrial pressure is higher than ventricular pressure
- AV valves open
- Slight bump in pressure due to atrial systole
In regards to pressure in the heart what happens during ventricular systole
- Ventricular pressure becomes higher than atrial pressure
- AV valves close
- First heart sound “lub”
- Ventricular pressure then becomes higher than aortic pressure
- Semi lunar valves open
- Blood moves out to the aorta
In regards to pressure what happens during ventricular diastole
- Ventricular pressure becomes lower than aortic pressure due to blood leaves the ventricle causing the chamber to relax
- Semi lunar valves close
- 2nd heart sound “Dub”
- Ventricular pressure then becomes lower than atrial pressure
- AV valves re-open
What is the Dicrotic notch
Where aortic walls are elastic
- When blood moves through them they stretch
- When blood leaves they recoil creating a small bump
- They keep the blood flowing
