Animal Transport 1 (Circulatory Systems and the Heart) Flashcards
Define an open transport system
Blood is not enclosed in vessels but bathes the cells directly (eg an insect)
Define a closed transport system
Blood is enclosed in blood vessels and is never in direct contact with cells
Define a single transport system
Blood passes through the heart once for each circuit of the body (eg a fish)
Define a double transport system
Blood passes through the heart twice for each circuit of the body (eg a human)
What is the disadvantage of a single circulatory system compared to a double?
Pressure is lost when blood passes through the capillaries of the gills. There is a lower pressure then going to the rest of the body
Describe the circulatory system of an earthworm
A closed circulatory system with haemoglobin
Describe the circulatory system of an insect
An open circulatory system with a fluid-filled body cavity (haemocoel). No oxygen is transported in the blood, this is instead done by the tracheal system
Which vein returns blood to the heart from the body?
The vena cava
Which vein returns blood to the heart from the lungs?
The pulmonary vein
Which artery takes blood from the heart to the body?
The aorta
Which artery takes blood from the heart to the lungs?
The pulmonary artery
Name the wall down the middle of the heart
The septum
Name the valves between the atria and the ventricles
Atrioventricular/bicuspid and tricuspid
Name the valves between the ventricles and the arteries
Semilunar/pulmonary and aortic
What does it mean that the heart muscle is myogenic?
It initiates its own contractions
Name the heart’s pacemaker
Sino Atrial Node
What is the purpose of the AVN?
The atrioventricular node delays the wave of excitation, allowing the atria to finish contracting and the ventricles to fully fill before the ventricles contract
What stops the electrical signal in the heart going straight from atria to ventricles?
A layer of non conductive connective tissue
Name the tissue that conducts electricity in the septum and ventricles of the heart
Bundle of His in septum/ purkyne/purkinje fibres
What does ECG stand for?
Electrocardiogram
Which blood vessels supply the heart muscle itself with oxygen and glucose?
Coronary arteries
What does the P wave of an ECG correspond to?
Depolarisation of the atria during atrial systole
What does the QRS complex of an ECG correspond to?
Spread of depolarisation through the ventricles resulting in ventricular systole
What does the T wave of an ECG correspond to?
The repolarisation of the ventricles during ventricular diastole
When do the atrioventricular valves open?
When the pressure in the atria is higher than in the ventricles (during ventricular diastole)
When do the atrioventricular valves close?
When the pressure in the ventricles is higher than the atria (during ventricular systole)
When do the semilunar valves open?
When the pressure in the ventricles is higher than in the arteries (during ventricular systole)
When do the semilunar valves close?
When the pressure in the arteries is higher than in the ventricles (during ventricular diastole)
Why does pressure in the aorta never drop to zero?
Elastic recoil of the aorta, which decreases the volume and increases the pressure. Also the fact the semi lunar valve closes, preventing backflow.
Why does the left ventricle have a thicker wall than the right?
It needs to pump blood at a higher pressure for the systemic circulation
