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Biology > 3.2 Transport in Animals > Flashcards

3.2 Transport in Animals Flashcards

1
Q

How are substances transported in single-celled organisms ?

A

Substances diffuse across an outer membrane.

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2
Q

How are substances transported in multicellular organisms ?

A

Use transport systems, such as circulatory systems for more efficient transport around the organism.

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3
Q

Why do multicellular organisms use transport systems ?

A

Large organisms, so have a small SA: volume ration and a higher metabolic rate. They are also more active so need a constant supply of glucose and oxygen. CO2 also needs to be removed quickly.

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4
Q

What are circulatory systems ?

A

Use blood to carry glucose and oxygen around the body. They also transport hormones, antibodies and waste products.

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5
Q

What is a single circulatory system ?

A

When blood only passes through the heart once in each complete circuit.

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6
Q

What is a double circulatory system ?

A

When blood passes through the heart twice in each complete circuit.

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7
Q

What is a closed circulatory system ?

A

All vertebrates have a closed circulatory system, where the blood is enclosed inside blood vessels.

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8
Q

What is an open circulatory system?

A

Some vertebrates have an open circulatory system, where blood isn’t enclosed in blood vessels all the time. Instead it flows freely through the body cavity.

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9
Q

What are arteries ?

A

They are blood vessels that carry blood away from the heart to the rest of the body. They carry oxygenated blood, except from the pulmonary arteries.

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10
Q

Why do arteries have thick, muscular walls ?

A

They need to withstand the high pressure as the heart beats.

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11
Q

Why do arteries have elastic tissues ?

A

They need to stretch and recoil as the heart beats.

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12
Q

Why is the inner lining of arteries folded ?

A

The endothelium is folded allowing it to contract.

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13
Q

What are arterioles ?

A

Branched from arteries and are much smaller. They have a layer of smooth muscle and has less elastic tissue.

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14
Q

Why does arterioles have smooth muscle in rings around arterioles ?

A

Allows them to expand or contract controlling amount of blood flowing to the tissues.

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15
Q

What are capillaries ?

A

Arterioles split into capillaries, which are the smallest blood vessel. Transports substances such as oxygen and glucose, which are exchanged between cells and capillaries.

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16
Q

How are capillaries adapted for gas exchange ?

A

They are one cell thick, so decreases diffusion distance making gas exchange more efficient.

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17
Q

What are venules ?

A

Capillaries connect to venules, which have thin cell walls that contain some muscle cells. Venules join together to form veins.

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18
Q

What are veins ?

A

Take blood back to heart under a low pressure. They contain valves to stop back flow of blood. All veins carry deoxygenated blood except for the pulmonary vein.

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19
Q

Why do veins have a wide lumen and little elastic or muscle tissue ?

A

Low pressure so don’t need to be as strong to withstand pressure. Wide lumen to allow more blood to flow back to heart.

20
Q

What helps veins transport blood back to the heart ?

A

Skeletal muscles help blood flow travel back to heart through veins.

21
Q

What is tissue fluid ?

A

Surrounds cells in tissues. It is made from substances that leave blood plasma.

22
Q

What is the function of tissue fluid ?

A

Cells take in oxygen and nutrients from the tissue fluid and release metabolic waste into it. Substances move out of capillaries into tissue fluid, by pressure filtration.

23
Q

What is the pressure like at capillary bed at start of pressure filtration ?

A

At start of capillary bed, nearest arteries, hydrostatic pressure inside capillaries is greater than hydrostatic pressure in tissue fluid.

24
Q

What does a difference in hydrostatic pressure cause in pressure filtration ?

A

Forces fluid out of capillaries and into spaces around cells, forming tissue fluid.

25
Q

What happens when tissue fluid leaves capillaries in pressure filtration ?

A

Hydrostatic pressure reduces in capillaries, so hydrostatic pressure is much lower at end of capillary bed, nearest venules.

26
Q

What happens as water leaves the capillaries in pressure filtration ?

A

Concentration of plasma proteins in capillaries increases and water potential decreases.

27
Q

What do plasma proteins generate in capillaries in pressure fluid ?

A

Plasma proteins in capillaries generate form of pressure, oncotic pressure, so at venule end of capillary bed, there is increased oncotic pressure and low water potential.

28
Q

What occurs due to water potential gradient in capillaries in pressure filtration ?

A

Because water potential in capillaries is lower than water potential in tissue fluid, some water then re-enters capillaries ,from tissue fluid, at venule end of osmosis.

29
Q

What happens to extra fluid that doesn’t re-enter capillaries ?

A

Extra tissue fluid gets returned to the blood through the lymphatic system (drainage system).

30
Q

What are the smallest lymph vessels ?

A

Lymph capillaries, where excess fluid passes into.

31
Q

What happens to excess fluid once it is inside the lymphatic system ?

A

Valves in lymph vessels stop lymph going backwards. Lymph gradually moves toward main lymph vessels in thorax.

32
Q

What is the left side of the heart responsible for ?

A

Pumps oxygenated blood to the rest of the body.

33
Q

What is the right side of the heart responsible for ?

A

Pumps deoxygenated blood to the lungs.

34
Q

What is the atrioventricular valve ?

A

Links atria to the ventricles.

35
Q

What is semi-lunar valve ?

A

Links ventricles to pulmonary artery and aorta..

36
Q

What is the purpose of valves in the heart ?

A

They stop blood flowing the wrong way, so prevents back flow.

37
Q

What does the valve opening depend on ?

A

Valves only open one way and whether they are open or closed depends on relative pressure of heart chambers. If there is a higher pressure behind valve, it is forced open. If there is a higher pressure in front of valve, it is forced shut.

38
Q

What is the direction of blood flow described as ?

A

Unidirectional.

39
Q

What is the cardiac cycle ?

A

Describes events in a single heartbeat. It is the ongoing sequence of contraction and relaxation of the atria and ventricles.

40
Q

When atria and ventricles contract and relax, what does this cause ?

A

Volumes of atria and ventricles change, which alters pressure. This causes valves to open and close, which moves blood through the heart.

41
Q

What is stage 1 of the cardiac cycle ?

A

The ventricles are relaxed and the atria contract, increasing pressure in atria and pushes blood into ventricles, through atrioventricular valves.

42
Q

What is stage 2 in cardiac cycle ?

A

The atria relax and ventricles contract and pressure becomes higher in ventricles, which forces atrioventricular valves to shut. Pressure in ventricles is higher than aorta and pulmonary artery, which forces blood into these arteries.

43
Q

What is stage 3 in cardiac cycle ?

A

Ventricles and atria relax. Higher pressure in pulmonary artery and aorta closes semi-lunar valves. Blood returns to the heart and atria fills again due to higher pressure in vena cava and pulmonary vein. Pressure in atria increases so atrioventricular valves open.

44
Q

What is cardiac output ?

A

Volume of blood pumped by heart per minute.

45
Q

How do you calculate cardiac output ?

A

heart rate (bpm) x stroke volume (cm3)

46
Q

What is stroke volume ?

A

Volume of blood pumped during each heartbeat.

Biology (10 decks)

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