Transport in animals- the heart Flashcards
what is the function of the aorta?
major artery which takes blood to the body
what is the function of the pulmonary artery?
major artery which takes blood to the lungs to be oxygenated
what is the function of the pulmonary veins?
major veins which bring oxygenated blood from the lungs back to the heart
what is the function of the vena cava?
major vein which brings deoxygenated blood from the body back into the heart
what is the function of the right atrium?
small chamber of the heart which forces deoxygenated blood into the right ventricle.
what is the function of the right ventricle?
large chamber of the heart which forces deoxygenated blood to the lungs.
what is the function of the left atrium?
small chamber of the heart which forces oxygenated blood into the left ventricle.
what is the function of the left ventricle?
large chamber of the heart which forces oxygenated blood around the body.
What is the function of the tricuspid and bicuspid (mitral) valves?
valves which stop backflow of blood into the atria.
what is the function of the semilunar (pulmonary/aortic) valves?
valves which stop backflow of blood into the ventricles.
what is the function of the tendinous cords?
stop valves from being turned inside out.
what is the function of the septum?
wall between the two chambers of the heart which stops oxygenated and deoxygenated blood mixing
what is the function of the cardiac muscle?
the muscle that the heart is made of, which beats rhythmically and does not fatigue like other muscle. It is myogenic (self stimulating).
what is the function of the coronary artery?
Artery which supplies the cardiac muscle with oxygenated blood so the heart doesn’t get fatigued.
Describe the movement of the blood on the right side of the heart? (1st, 2nd and 3rd step)
1) Deoxygenated blood enters right atrium through vena cava at low pressure.
2) Pressure builds in atrium until tricuspid valve is forced open, and blood flows into right ventricle.
3) When both the atrium and ventricle are full, the atrium contracts forcing extra blood into the ventricle, stretching the ventricular walls.
Describe the movement of the blood on the right side of the heart? (4th and 5th step)
4) The tricuspid valve closes, the ventricle contracts and the pulmonary semilunar valve is forced open and blood passes through out to the lungs.
5) Pulmonary semilunar valve closes.
Describe the movement of blood on the left side of the heart? (1st, 2nd, 3rd step)
1) Oxygenated blood from the body enters the left atrium through the pulmonary vein.
2) Pressure builds in atrium into bicuspid valve is forced open, and blood flows into left ventricle.
3) When both the atrium and ventricle are full, the atrium contracts and forces extra blood into the ventricle, stretching the ventricular walls.
Describe the movement of blood on the left side of the heart? (4th, 5th step)
4) The bicuspid valve closes and the ventricle contracts, forcing the aortic semilunar valve open and the blood passes out to the lungs.
5) The aortic semilunar valve closes.
what is diastole?
Where the cardiac muscle is in a relaxed state.
what is systole?
Where the cardiac muscle is contracting.
where does deoxygenated blood from the body flow?
into the right side of the heart which pumps into the lungs
where does the oxygenated blood from the lungs flow?
into the left side of the heart which pumps into the body
what prevents the blood from over distending with blood?
the heart is surrounded by inelastic pericardial membranes
why is the muscular wall of the left side much ticker than the right?
left side must pump blood to the rest of the body which is a longer distance than to the lungs. The left side also needs to produce sufficient force to overcome the resistance of the aorta and arterial systems of the whole body
What occurs during diastole?
the chambers fill, the volume and pressure in the heart increases but the pressure in the arteries is at its minimum.
What occurs during systole?
blood is forced out of the chambers. Volume decreases rapidly and pressure increases rapidly as chambers contract. Pressure in arteries is at a maximum, due to pulse surge.
how is the Lub-dub sound created from a stethoscope?
first sound comes as the blood is forced against the atrio-ventricular valves and the ventricles contract. The second sound comes as a back flow of blood closes the semilunar valves in the aorta and pulmonary artery as the ventricles relax.
what is the cardiac muscle described as and why?
it is a myogenic cardiac muscle which stimulates its own wave of excitement which travels through the purkyne fibres and causes the chambers of the heart to contract.
what is the cardiac output equation?
cardiac output (ml/minute)= stroke volume (ml/beat) times heart rate (beats/min)
what is cardiac output?
the volume of blood pumped from each ventricle per minute
why do individuals who are fitter often have a higher cardiac output?
due to having thicker and stronger ventricular muscles
when does cardiac output increases?
when exercising so blood supply can meet the increases metabolic demands of the cells
what is heart rate?
beats per minute (cardiac cycles per minute)
what is stroke volume?
volume of blood pumped out of the left ventricle during one cardiac cycle
Function of the SAN (pacemaker)
initiates wave of excitation in right atrium, then to left atrium.
Why can the wave of excitation only travel through the AVN (conducting tissue)?
because other parts of the heart have high electrical resistance due to collagen
why is the AVN stimulated after a slight delay?
to ensure the atria contracts and is empty before ventricles contract
where does the wave of excitement travel after AVN?
to the bundle of his (conducting tissue), middle of the heart. It divides into two purine tissue and carries the stimulation. The purine fibres along the ventricles initiates wave of excitation from apex (bottom) of the heart, causing ventricles to contract.
what is an ECG?
electrocardiogram which shows a number of electrical waves produced by the activity of the heart.
Describe the ECG
P=excitation of atria
QRS=excitation of ventricles
T=repolarisation of ventricle (ventricular diastole)
