Circulation Flashcards
What’s an open circulation system?
- ‘blood’ is not contained in vessels
- haemolymph bathes tissues directly
- haemolymph returns slowly back to the heart
- insects specifically have no haemglobin
What’s a closed circulation system?
- blood is contained in vessels
- organs do not have direct contact with blood
How many pumps (hearts) does a worm have?
Worms have 5 pseudohearts
List advantages of a double circulatory system
- maintains high blood pressure
- allows for lower pressures in pulmonary circulation
- circulation is faster
- oxygenated and deoxygenated blood is kept separate
Describe the structure of an artery
Tunica Externa = collagen fibres
Tunica Media = elastic fibres, smooth muscles
Tunica Intima = elastic membranes
Endophelium = 1 cell thick, smooth lining
Describe the structure of a vein
Tunica Externea = collagen fibres
Tunica Media = thinner than arteries
Tunica Intima = protection, elastic membrane
Ethilium = 1 cell thick, reduces friction
Describe the structure of capillaries
Endothelium = 1 cell thick, small gaps between cells, capillary to veins
Describe blood flow in the heart
From heart to atery to arteriole to capillary to venule to vein and back to the heart
List key feautures of the heart
aorta, superior vena cava, semi-lunar valve, tricuspid valve, inferior vena cava, right ventricle, right atrium, left ventricle, left atrium, semi-lunar valvue, biscuspid valve, pulmonary vein, pulmonary artery
What is the fnction of the cardiac muscle?
- myogenic contraction
- heart rate modified by nervous and hormone situation
- cardiac muscle never tires
What is an atrial systole?
where both atria contracts and blood flows from atria into ventricles
What is the ventricular systole?
Where both ventricles contract and atrioventricles valves are pushed shut by pressure of blood in ventricles
How are heart rates regulated?
Nerve impulses from the medulla oblongata in the brain
Describe the electrical system of the heart
- SAN sends out wave of excitation across the muscle of the atria
- wave passes to the atrioventricular node that delays the wave of excitation and allows atria to finish contraction
- AVN passes the wave of excitation to bundle of His in the septum, transmits the wave to apex of the heart
- wave passes through purkinje fibres in muscle of ventricals
What does the P represent on the electrocardiogram?
P = respents the wave of depolarisation of the atrial walls
What does QRS represent on the electrocardiogram?
QRS = depolarisation of the ventricular walls causing a ventricular systole
What does the T represent in the electrocardiogram?
T = repolarisation of ventricular walls during ventricular diastole
What is the composition of blood?
Cells = -45% (erythrocytes, luekocytes, thrombocytes)
Plasma = -55% (water, proteins, ions, nutrients, waste products, hormones, gases)
What are the adaptations for Red blood cells
- flattened biconcave disc shape
- no nucleus or organelles
- flexible shapes to squash close to capillary wall to provide short diffusion pathways
What type of protein is haemoglobin?
Globular
What’s the affinity of oxygen?
oxygen + haemoglobin -> oxyhaemoglobin
4O2 + Hb -> Hb4O2
Name three ways CO2 is carried
- 5% is dissolved in plasma
- 10% combines with haemoglobin to form carboninohaemoglobin
- 85% transported hydrogencarbonate ions
What happens to carbonic acid?
It dissociates into protons (H+) and hydrogen carbonate ios (HCO3)
the HCO3 diffuse into plasma
The chloride shift balances the charge in plasma (swaps hydrogen with carbonate)
Oxygens displaced by protons
Describe the Bohr effect
low CO2 means the saturation of haemoglobin with O2 is higher
high CO2 means the saturation of haemoglobin with O2 shifts to the left and decreases
