Transport Systems/ Heart/ Blood

Question 1

The need of transport systems (3):

Answer 1

-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

Question 2

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

Answer 2

• 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

Question 3

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

Answer 3

• 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

Question 4

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

Answer 4

• 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

Question 5

Single circulatory system:

Answer 5

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).

Question 6

Double circulatory system

Answer 6

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.

Question 7

Which system is more efficient?

Answer 7

Double circulatory system

Question 8

Explain why a double circulatory system is more efficient:

Answer 8

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).

Question 9

Function of arteries and arterioles:

Answer 9

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

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

Question 10

What do arterioles link?

Answer 10

Arteries and capillaries

Question 11

Structure of arterioles in comparison to arteries?

Answer 11

They have more smooth muscle and less elastic fibres

Question 12

What happens when smooth muscles contract and relax?

Answer 12

Contracting leads to the blood vessels to constrict (vasoconstriction)

Relaxing leads to blood vessels to expand (vasodilation)

Question 13

Collagen:

Answer 13

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

Question 14

Smooth muscle:

Answer 14

Contracts or relaxes, changes size of the lumen

Question 15

Elastic fibres:

Answer 15

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

Question 16

Lumen:

Answer 16

The channel within the blood vessel

Question 17

Structure of arteries:

Answer 17

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

Question 18

Veins and venules function:

Answer 18

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

Question 19

What do venules link?

Answer 19

The veins and capillaries

Question 20

Venules structure compared to veins:

Answer 20

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

Question 21

Vein structure:

Answer 21

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)

Question 22

Explain the blood pressure in veins:

Answer 22

• 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.

Question 23

Capillaries structure:

Answer 23

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).

Question 24

Capillaries function:

Answer 24

• 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

Question 25

Adaptations of capillaries:

Answer 25

-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

Question 26

Tendinous cords

Answer 26

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

Question 27

Right atrium (structure)

Answer 27

Have thin muscular walls

Question 28

Vena cava

Answer 28

Consists of the superior and inferior vena cava

Carriers deoxygenated blood from the whole body

Question 29

Right Atrioventricular Valve (tricuspid valve) function:

Answer 29

Prevents back flow of blood

Question 30

Aorta (function):

Answer 30

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

Question 31

Pulmonary artery

Answer 31

Carries away deoxygenated blood to the lungs

Question 32

Pulmonary vein

Answer 32

Brings in oxygenated blood from the lungs

Question 33

Semilunar valves

Answer 33

Prevent back flow of blood into the heart

Question 34

Left atrium

Answer 34

They have thin muscular walls

Question 35

Left Atrioventricular Valve (bicuspid valve) function:

Answer 35

Prevent back flow of blood

Question 36

Septum

Answer 36

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

Question 37

Myogenic

Answer 37

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

Question 38

What does blood consist off?

Answer 38

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

Question 39

What does plasma carry?

Answer 39

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.

Question 40

List 3 the plasma proteins and their functions

Answer 40

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

Question 41

What are platelets and their function?

Answer 41

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

Question 42

Functions of the blood?

Answer 42

• 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

Question 43

What can move in and out of capillaries through tiny pores

Answer 43

Plasma along with substances dissolved in it

Question 44

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

Answer 44

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.

Question 45

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

Answer 45

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

Question 46

How does tissue fluid work

Answer 46

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

Question 47

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

Answer 47

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.

Question 48

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

Answer 48

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

Question 49

The carriage of CO2

Answer 49

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”).

Question 50

How is lymph formed?

Answer 50

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).

Question 51

What is lymph?

Answer 51

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.

Question 52

What is the role of lymph

Answer 52

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

Question 53

What are lymph nodes, and their function?

Answer 53

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.