Circulation

Question 1

What’s an open circulation system?

Answer 1

• ‘blood’ is not contained in vessels
• haemolymph bathes tissues directly
• haemolymph returns slowly back to the heart
• insects specifically have no haemglobin

Question 2

What’s a closed circulation system?

Answer 2

• blood is contained in vessels
• organs do not have direct contact with blood

Question 3

How many pumps (hearts) does a worm have?

Answer 3

Worms have 5 pseudohearts

Question 4

List advantages of a double circulatory system

Answer 4

• maintains high blood pressure
• allows for lower pressures in pulmonary circulation
• circulation is faster
• oxygenated and deoxygenated blood is kept separate

Question 5

Describe the structure of an artery

Answer 5

Tunica Externa = collagen fibres
Tunica Media = elastic fibres, smooth muscles
Tunica Intima = elastic membranes
Endophelium = 1 cell thick, smooth lining

Question 6

Describe the structure of a vein

Answer 6

Tunica Externea = collagen fibres
Tunica Media = thinner than arteries
Tunica Intima = protection, elastic membrane
Ethilium = 1 cell thick, reduces friction

Question 7

Describe the structure of capillaries

Answer 7

Endothelium = 1 cell thick, small gaps between cells, capillary to veins

Question 8

Describe blood flow in the heart

Answer 8

From heart to atery to arteriole to capillary to venule to vein and back to the heart

Question 9

List key feautures of the heart

Answer 9

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

Question 10

What is the fnction of the cardiac muscle?

Answer 10

• myogenic contraction
• heart rate modified by nervous and hormone situation
• cardiac muscle never tires

Question 11

What is an atrial systole?

Answer 11

where both atria contracts and blood flows from atria into ventricles

Question 12

What is the ventricular systole?

Answer 12

Where both ventricles contract and atrioventricles valves are pushed shut by pressure of blood in ventricles

Question 13

How are heart rates regulated?

Answer 13

Nerve impulses from the medulla oblongata in the brain

Question 14

Describe the electrical system of the heart

Answer 14

• 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

Question 15

What does the P represent on the electrocardiogram?

Answer 15

P = respents the wave of depolarisation of the atrial walls

Question 16

What does QRS represent on the electrocardiogram?

Answer 16

QRS = depolarisation of the ventricular walls causing a ventricular systole

Question 17

What does the T represent in the electrocardiogram?

Answer 17

T = repolarisation of ventricular walls during ventricular diastole

Question 18

What is the composition of blood?

Answer 18

Cells = -45% (erythrocytes, luekocytes, thrombocytes)
Plasma = -55% (water, proteins, ions, nutrients, waste products, hormones, gases)

Question 19

What are the adaptations for Red blood cells

Answer 19

• flattened biconcave disc shape
• no nucleus or organelles
• flexible shapes to squash close to capillary wall to provide short diffusion pathways

Question 20

What type of protein is haemoglobin?

Answer 20

Globular

Question 21

What’s the affinity of oxygen?

Answer 21

oxygen + haemoglobin -> oxyhaemoglobin
4O2 + Hb -> Hb4O2

Question 22

Name three ways CO2 is carried

Answer 22

1. 5% is dissolved in plasma
2. 10% combines with haemoglobin to form carboninohaemoglobin
3. 85% transported hydrogencarbonate ions

Question 23

What happens to carbonic acid?

Answer 23

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

Question 24

Describe the Bohr effect

Answer 24

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