3.3.4.1 mass transport in animals - circulation

Question 1

what is the role of the papillary muscles and tedious cords?

Answer 1

help prevent the back flow of blood restricting movement of atrioventricular valves.

Question 2

what is the route of deoxygenated blood?

Answer 2

inferior/superior vena cava > right atrium > tricuspid valve > right ventricle > semi-lunar valves > pulmonary artery

Question 3

what is the route of oxygenated blood?

Answer 3

pulmonary vein > left atrium > bicuspid valves > left ventricle > semi-lunar valves > aorta

Question 4

what is atrial systole?

Answer 4

• atria pressure increases then decreases as blood leaves the ventricles, volume decreases as blood leaves.
• ventricle pressure and volume slightly increases.
• artery pressure and volume is low.
• atrioventricular values are open.
• semi-lunar valves are closed.

Question 5

what is diastole?

Answer 5

• atria pressure stays low and volume slightly increases.
• ventricle pressure is low and volume increases as they refill.
• arteries pressure and volume decreases as blood flows away from heart.
• atrioventricular valves open.
• semi-lunar valves close.

Question 6

how is blood flow unidirectional?

Answer 6

• pressure differences cause movement of blood.
• valves create barriers.

Question 7

what is ventricular systole?

Answer 7

• atria pressure stays low and volume of blood is low but atrium starts to refill.
• ventricle pressure increases and is high, however volume decreases as blood starts to empty from ventricles.
• arteries have an increased pressure and volume as blood entering arteries.
• atrioventricular valves closed.
• semi-lunar valves open.

Question 8

what vessel takes blood from the lungs to the heart?

Answer 8

pulmonary vein

Question 9

what vessel takes blood away from the heart?

Answer 9

aorta

Question 10

what vessel takes blood to the liver?

Answer 10

hepatic artery

Question 11

what vessel takes blood from the stomach and intestines to the liver?

Answer 11

hepatic portal vein

Question 12

what vessel takes blood to the kidneys?

Answer 12

renal artery

Question 13

what vessel takes blood away from the kidneys?

Answer 13

renal vein

Question 14

what vessel takes blood away from the liver?

Answer 14

hepatic vein

Question 15

what vessel brings blood to the heart?

Answer 15

vena cava

Question 16

what vessel takes blood from the heart to the lungs?

Answer 16

pulmonary artery

Question 17

what is the role of arteries?

Answer 17

to carry (mostly oxygenated) blood at high pressures away from the heart. transports blood under highest pressures from heart to organs.

Question 18

what is the size of muscle and elastic layers in the artery?

Answer 18

muscle layer: thick to control, contract and withstand pressure.
elastic layer: thick to stretch and recoil to maintain pressure.

Question 19

does the arteries have valves and what is the size of their lumen?

Answer 19

valves: no.
lumen: small to maintain pressure.

Question 20

what is a systemic circulation system?

Answer 20

to the body.

Question 21

what is a pulmonary circulation system?

Answer 21

to the lungs.

Question 22

what is the role of arterioles?

Answer 22

join arteries and capillaries.

Question 23

what is the size of muscle and elastic layers in the arterioles?

Answer 23

muscle layer: relatively thick.
elastic layer: thinner than arteries.

Question 24

does the arterioles have valves and what is the size of their lumen?

Answer 24

valves: no.
lumen: smaller than arteries.

Question 25

what is the role of capillaries?

Answer 25

branched to supply cells with materials through diffusion.

Question 26

what is the size of capillaries lumen?

Answer 26

very small - one red blood cell can fit.

Question 27

what is the role of the veins?

Answer 27

supply blood back to heart.

Question 28

what is the size of veins elastic and muscular layer?

Answer 28

thin.

Question 29

do veins have valves and what size is their lumen?

Answer 29

valves: yes to prevent back flow. lumen: large.

Question 30

how does the structure of capillaries relate to success of exchange of substance between blood and tissue fluid surrounding cells?

Answer 30

- single layer of flattened endothelial cells = reduces diffusion distance for rapid diffusion. - basement membrane of connective tissue = many capillaries in net work, branch between cells to minimise diffusion distance. - narrow, reduced velocity of blood-flow (narrow lumen), more time for exchange.

Question 31

how is tissue fluid formed?

Answer 31

- at the arteriole end in the capillary the hydrostatic pressure is higher, which pushes fluid out of capillary. - opposed by water potiental of blood which is lower than the tissue fluid and hydrostatic pressure of tissue fluid.

Question 32

how is tissue fluid reabsorbed?

Answer 32

- at the venous formation of tissue fluid reduces water potential of blood on the plasma proteins cannot cross basement membrane but volume of water has decreased, causing fluid to move into capillary. - the hydrostatic pressure falls. - some tissue fluid drains into the lymphatic system.

Question 33

what happens when tissue fluid is absorbed into the lymphatic system?

Answer 33

- forms lymph = colourless pale yellow fluid containing lipids. - lymphatic system drains into circulation system near vena cava via the thoracic duct. - lymph nodes = trap pathogens and foreign substances, containing lots of NBCs (swollen lymph nodes are a sign that they are working hard). - lymphatic tissue also contains lots of NBCs.

Question 34

what is the heart?

Answer 34

myogenic, so can generate electrical activity.

Question 35

what is the SAN?

Answer 35

sinoatrial node

Question 36

what is the AVN?

Answer 36

atrioventricular node

Question 37

how is the contractions of the heart controlled?

Answer 37

1) the SAN depolarises and produces an electrical impulse (wave of excitation). 2) the wave of excitation spreads across the atrium causing the left and right atrium to contract = atrial systole. 3) the wave of excitation reaches a layer of non-conductive tissue between the atria and ventricles causing a delay = gives the atria time to push blood into the ventricles and empty. 4) the wave of excitation gathers at the AVN. 5) the AVN passes the wave to the base of the ventricles along the bundle of his. 6) the wave is then passed to the pwkinje fibres which branch up the outer walls of ventricles = this causes the ventricles to contract from the base upwards (ventricular systole), which pushes blood into pulmonary artery and aorta.

Question 38

what is the autonomic nervous system?

Answer 38

to control essential body pressures e.g heart rate and temperature.

Question 39

what are the receptors in the heart?

Answer 39

baron receptors detect pressure.

Question 40

what type of receptors are in the carotid arteries?

Answer 40

chemoreceptors and baron receptors detecting pH and pressure.

Question 41

where do the input sensory neurones lead to?

Answer 41

cardiovascular centre of medulla oblongata.

Question 42

what does sympathetic mean?

Answer 42

speeds things up (accelerator nerves).

Question 43

what does parasympathetic mean?

Answer 43

slows things down (decelerator nerves).

Question 44

what is cardiovascular disease?

Answer 44

- general term for conditions that affect heart and blood vessels. - usually associated with atherosclerosis and increased risk of blood clots. - includes: coronary heart disease, strokes, peripheral arterial disease.

Question 45

what is atherosclerosis?

Answer 45

- fats are transported in blood as lipoproteins. - LDL more fats, specially cholesterol. - HDL more proteins.

Question 46

what are the stages of heart disease?

Answer 46

1) damage to epithelium (chemicals, high salt, high pressure etc). 2) LDLs deposited in wall. 3) phagocytes engulf LDLs and form foam cells (which remain in wall). 4) fibrous collagen fibres and smooth muscle build up to contain the damage. 5) plaque build up over time, narrowing, blood clot may form = blockage.

Question 47

what factors increase chances of heart disease?

Answer 47

- smoking. - diet, high salt, cholesterol and saturated fats. - exercise. - high blood pressure. - genetic tendency. - age. - gender.

Question 48

how can rate of blood flow be determined?

Answer 48

cardiac output = stroke volume x heart rate