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A Level Biology > Transport Systems/ Heart/ Blood > Flashcards

Transport Systems/ Heart/ Blood Flashcards

1
Q

The need of transport systems (3):

A

-Large multicellular organisms cannot rely on diffusion alone
(SA:V too small; metabolic demand is too high)

  • Diffusion distances are too great
  • Nutrients, waste, and messaging molecules (e.g hormones) must be transported from one place to another
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2
Q

What are some aspects that both an opened and closed system share?

A
  • Have a liquid transport medium (e.g blood)
  • Have vessels that carry the transport medium
  • A pumping mechanism to move the fluid around
  • Mass transport systems
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3
Q

What are some aspects that are unique to closed systems only (5)?

A
  • Blood is enclosed in blood vessels (doesn’t come into direct contact with the cells of the body)
  • Heart pumps the blood around the body under pressure and relatively quickly
  • Blood returns directly to the heart
  • Substances leave and enter the body by diffusion, through the walls of the blood vessels
  • The amount and of blood flowing to a particular tissue can be altered/ adjusted via vasoconstriction and vasodilation
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4
Q

What are some aspects that are unique to open systems only (5)?

A
  • Very few vessels to contain transport medium
  • Pumped straight from the heart to the body cavity (haemocoel)
  • In the haemocoel the transport medium travels under a low pressure
  • Comes into direct contact with the tissues and the cells (where exchange takes place)
  • Transport medium returns back to the heart through an open-ended vessel
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5
Q

Single circulatory system:

A

Blood flows through the heart and is pumped out to travel all around the body before returning back to the heart (i.e blood travels only once through the heart for each complete circulation of the body).

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6
Q

Double circulatory system

A

Blood travels twice through the heart for each full circuit of the body. Each circuit- to the lungs then the body- each only pass one capillary network, meaning a relatively high pressure and fast flow of blood can be maintained.

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7
Q

Which system is more efficient?

A

Double circulatory system

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8
Q

Explain why a double circulatory system is more efficient:

A

Blood typically travels at a lower pressure in a single circulatory system, because blood’s pumped once round the circulatory system and then have to pass through the 2 capillary networks before completing one full loop. Whereas in the double circulatory system blood is pumped twice and therefore only has to travel through one capillary bed before returning back to the heart, each time).

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9
Q

Function of arteries and arterioles:

A

Carry blood away from the heart to the tissues of the body

They always carry oxygenated blood (pulmonary artery an exception).

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10
Q

What do arterioles link?

A

Arteries and capillaries

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11
Q

Structure of arterioles in comparison to arteries?

A

They have more smooth muscle and less elastic fibres

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12
Q

What happens when smooth muscles contract and relax?

A

Contracting leads to the blood vessels to constrict (vasoconstriction)

Relaxing leads to blood vessels to expand (vasodilation)

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13
Q

Collagen:

A

Provides structure support to maintain the shape and volume of the vessel

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14
Q

Smooth muscle:

A

Contracts or relaxes, changes size of the lumen

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15
Q

Elastic fibres:

A

Composed of elastin, can stretch and recoil, providing vessels with flexibility

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16
Q

Lumen:

A

The channel within the blood vessel

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17
Q

Structure of arteries:

A

Elastic fibres, withstand pressure/ force, as they have the ability to stretch (within limits of the collagen), in between the contractions of the heart they recoil to original length evening out the surge of blood pumped (giving a continuous flow).

Lining of the artery made from endothelium, smooth so blood can flow over it more easily

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18
Q

Veins and venules function:

A

Carry deoxygenated blood away from cells to the heart (pulmonary vein an exception).

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19
Q

What do venules link?

A

The veins and capillaries

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20
Q

Venules structure compared to veins:

A

They have a very thin walls with little smooth muscle, serval venules join together into a vein

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21
Q

Vein structure:

A

Wide lumen and a smooth thin lining (endothelium) easier for blood to flow.
Thin layer of elastic fibres
Lots of collagen
Large reservoir of blood (up to 60% of your total blood)

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22
Q

Explain the blood pressure in veins:

A
  • Very low in comparison to arteries
  • They do not have a pulse (surges from the heart pumping is lost when blood flows through narrow capillaries).
  • The majority of the venous system have valves to prevent backflow.
23
Q

Capillaries structure:

A

Microscopic blood vessels
Lumen so small that red blood cells have to travel through in single file.
They are one endothelium cell thick
The gaps between the endothelium cells are relatively large (where many substances pass out, into the fluid surroundings of the cell).

24
Q

Capillaries function:

A
  • They link arterioles and venules (they form a network)
  • Substances exchange through the capillary walls
  • The blood entering is oxygenated and the blood leaving is deoxygenated
25
Q

Adaptations of capillaries:

A

-Very large SA:V area of the capillaries for diffusion
-Total cross sectional area of the capillaries is always greater then that of the arteries supplying the blood, therefore rate of blood flow falls
Relatively slow flow of blood through the capillaries increases time for exchange to take place
-Walls are one endothelial cell thick, providing a thin layer for diffusion

26
Q

Tendinous cords

A

Help prevent the valves from turning inside out by the pressure excreted when the ventricles contract

27
Q

Right atrium (structure)

A

Have thin muscular walls

28
Q

Vena cava

A

Consists of the superior and inferior vena cava

Carriers deoxygenated blood from the whole body

29
Q

Right Atrioventricular Valve (tricuspid valve) function:

A

Prevents back flow of blood

30
Q

Aorta (function):

A

Carries away oxygenated blood to the rest of the body at a high pressure

31
Q

Pulmonary artery

A

Carries away deoxygenated blood to the lungs

32
Q

Pulmonary vein

A

Brings in oxygenated blood from the lungs

33
Q

Semilunar valves

A

Prevent back flow of blood into the heart

34
Q

Left atrium

A

They have thin muscular walls

35
Q

Left Atrioventricular Valve (bicuspid valve) function:

A

Prevent back flow of blood

36
Q

Septum

A

The inner dividing wall of the heart, prevents the mixing of deoxygenated blood and oxygenated blood.

37
Q

Myogenic

A

Body parts that would initiate their own contraction (not ideally linked and controlled by the brain). The cardiac muscle of the heart can initiate its own contraction

38
Q

What does blood consist off?

A

55% plasma, 45% blood cells
Consists of yellow liquid (plasma)
Most of the plasma is water

39
Q

What does plasma carry?

A

A wide variety of components (i.e dissolved glucose, amino acids, mineral ions , hormones, and the large plasma proteins). It also carriers red blood cells and many white blood cells and platelets.
Only plasma and red blood cells are involved in the transport of blood.

40
Q

List 3 the plasma proteins and their functions

A

Albumin (important maintain the osmotic potential of the blood)
Fibrinogen (blood clotting)
Globulins (involved in transport and the immune system)

41
Q

What are platelets and their function?

A

Fragments of large cells called megakaryocytes (found in bone marrow), involved in clotting mechanism in the blood.

42
Q

Functions of the blood?

A
  • Transport of O2 and CO2 from respiring cells
  • Digested food from the small intestine
  • Nitrogenous waste products from the cells to the excretory organs
  • Chemical messages (hormones)
  • Food molecules from storage compounds to cells that need them
  • Platelets to damaged areas
  • Cells and antibodies involved in the immune response
  • Maintenance of steady body temp and acts as buffer, minimising pH changes
43
Q

What can move in and out of capillaries through tiny pores

A

Plasma along with substances dissolved in it

44
Q

The movement of plasma and solute is determined by which two competing pressures

A

Hydrostatic pressure inside the vessels (resulting from contractions in the heart) pushes plasma and solutes out of the capillary (The fluid that leaves the capillary is referred to as tissue fluid)

Pressure resulting from plasma proteins that are too big to get out of the capillaries. The pressure is referred to as oncotic pressure (i.e. it is caused by low water potential, this acts to push the tissue fluid back into the capillaries.

45
Q

What happens to the amount of tissue fluid as a blood moves along the capillaries

A

The difference between the two competing pressures change, causing changes in the ‘net flow’

46
Q

How does tissue fluid work

A

It flows around the tissues, where diffusion takes place (delivering nutrients and removing waste).

47
Q

In terms of tissue fluid what is happening at the arterial end of the capillary

A

Hydrostatic pressure, created by the heart contracting, Is greater than the oncotic pressure (the attraction of water, by osmosis, that results from plasma proteins). Therefore what I need the capillaries through small gaps in the capillary wall, tissue fluid circulates around the sales and exchange takes place.

48
Q

In terms of tissue fluid what is happening at the venous end of the capillary

A

The oncotic pressure is now greater than the hydrostatic pressure, fluid moves back into the capillaries carrying waste products

49
Q

The carriage of CO2

A

CO2 diffuses into the blood stream
5% remains dissolved in the plasma
95% diffuses into rbcs into the cytoplasm
10-20% binds to Hb forming carbaminohaemoglobin
75-85% converted to H2CO3 by carbonic anhydrase
H2CO3 dissociates into H+ and HCO3 -
H+ ions removed by buffers, especially Hb
HCO3 - moves out of rbc in exchange for Cl-
Cl- diffuses in, to maintain electrochemical balance (“chlorine shift”).

50
Q

How is lymph formed?

A

Some tissue fluid doesn’t return to the capillaries (10% that leaves blood vessels drain into a system of blind ended tubes called lymph capillaries).

51
Q

What is lymph?

A

It’s similar in composition to plasma and tissue fluid but has less oxygen and fewer nutrients. Also contains fatty acids, which have been absorbed into the lymph from the villi of the small intestine.

52
Q

What is the role of lymph

A

Lymph capillaries join up to form larger vessels. Fluid transported through them by the squeezing of the squeezing of the body muscles and one-way valves to prevent backflow of lymph. Eventually the lymph returns to the blood, flowing into the right and left subclavian veins.

The lymphatic system plays a major role in the defence mechanisms of the body

53
Q

What are lymph nodes, and their function?

A

They are found along lymph vessels. Lymphocytes build up there, when necessary and produce antibodies, which are then passed into the blood.

Lymph nodes also intercept bacteria and other debris from the lymph, which are ingested by phagocytes found in the nodes.

A Level Biology (20 decks)

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