Transport in Animals M3

Question 1

Explain and compare the circulatory systems of a fish and a mammal.

Answer 1

Fish - a heart, with one ventricle and atrium, closed single system, lower metabolic rate, ectotherms. Mammals - a heart with two ventricles and two atria. Close double circulatory system, blood is pumped faster at a higher pressure

Question 2

Compare a closed and open circulatory system.

Answer 2

Closed, blood is carried in vessels where gases can be exchanged (fish/mammals) Supports high metabolic processes, more effective at transport blood all around the body. Open, means they don’t have veins and the blood flows freely through the cavities of the body and blood comes in direct contact with cells, where exchange happens.. (insects)

Question 3

What are the main reasons that make a transport system necessary in an animal?

Answer 3

1. cells need oxygen + nutrients and to remove CO2. 2. diffusion pathway is large so diffusion is to slow. 3. With larger animals, their SA:V ration decrease and their so demand for oxygen + nutrients are greater than possible supply. 4. As activity increase, metabolic rate increase, need for O2 + nutrients increases and high oxygen demand can not be met with diffusion alone. 5. land animals are to dry for diffusion, need a moist surface,

Question 4

How do capillary networks change pressure and blood flow rate

Answer 4

slows blood down and it provides resistance so that diffusion can occur.

Question 5

Suggest why insects can have an open circulatory system but not mammals.

Answer 5

The blood in insects does not carry oxygen to the tissues or collect carbon dioxide because the system of tracheae and tracheoles carries out this function.
Therefore there is no need for a highly efficient circulatory system.
In mammals, blood must deliver oxygen efficiently to the tissues and remove CO2 as well as glucose.

Question 6

Explain Diastole

Answer 6

The ventricle walls relax and the pressure in the ventricles falls. Blood starts to flow from the atria into the ventricles again. Atrial pressure is higher than the ventricular.

Question 7

Explain Atrial systole

Answer 7

The walls of the atria contract. This reduces the volume of the atria, increasing the pressure. More blood passes through the already open atrioventricular valves into the ventricles.

Question 8

Explain ventricular systole

Answer 8

The walls of the ventricles now contract, reducing the volume in the ventricles. The pressure increases and blood is forced into the arteries. Atria walls relax and starting to fill again

Question 9

Describe the layers in blood vessels.

Answer 9

TUNICA EXTERNA - a thick layer of COLLAGEN gives strength to the wall so it can WITHSTAND high pressures. TUNICA MEDIA - Eklastic fibres STRETCH when the hearts in systole and RECOILS when its in diastole to MAINTAIN pressure.

Question 10

Why are arterioles important?

Answer 10

Control distributions of blood, by vasoconstriction and vasodilation, so they have a high proportion of smooth muscle

Question 11

How are veins adapted to their function

Answer 11

Blood pressure is low, so walls are thin and valves help maintain blood flow in the right direction

Question 12

How are capillaries adapted to their function?

Answer 12

1. one cell thick endothelium makes a short diffusion pathway for blood. 2. large SA for diffusion 3. permeable to gases, water and solutes. 4. narrow lumen offers resistance to flow giving time for diffusion to take place. 5.

Question 13

Describe and explain how tissue fluid is formed and reabsorbed as blood flows along a capillary …6 marks

Answer 13

At the ARTERIOLE END of the capillary, the HYDROSTATIC PRESSURE is high
It is greater than the force created by water potential-(ONCOTIC POTENTIAL) so fluid (water and solutes) are forced out through the gaps in the capillary.
PLASMA PROTEINS and cells are too large to leave the capillary and produce high oncotic pressure and low water potential.
At the VENULE END of the capillary, the oncotic pressure is now HIGHER THAN the hydrostatic pressure, so water returns into the capillary by OSMOSIS, down a water potential gradient.
Some TISSUE FLUID is absorbed into LYMPH VESSELS.

Question 14

Where does loading take place?

Answer 14

the capillaries in the lungs, where there is lots of oxygen. Oxygen combines with haemoglobin to form oxyhemoglobin

Question 15

Where does unloading take place?

Answer 15

the capillaries of the tissues where the partial pressure of oxygen is low (ppO2). Oxygen dissociates from haemoglobin.

Question 16

key points that cause the Bohr shift/effect.

Answer 16

1. muscle contraction causes respiration rate to go up. 2. More CO2 is produced by tissues/muscle cells 3. Lowers the pH of the blood, as more CO2 is dissolved in it, becomes more acidic. 4. Causes haemoglobin to change shape. 5. Haemoglobin releases and it unloads its oxygen is available to the cells fro respiration

Question 17

How is CO2 transported through the blood in different ways.

Answer 17

5% of CO2 transported in solution in the plasma. 10% is transported, as it combines with haemoglobin as carboaminohaemoglobin. 85% is transported as hydrogen carbonate ios (HCO-) in the blood.