3.1.2 Transport In animals

Question 1

Describe the circulatory system of humans

Answer 1

Closed,double circulatory system. Blood within the system flows through the heart twice for each circuit of the body. 2 seperate circuits: pulomnary circuit,blood flows from the heart to the lungs for gas exchange and then returns back to the heart. Systemic circuit where blood flows from heart to the rest of the body tissues. Blood floes through the pulomnary circuit, then systemic circuit, and then return to the heart to go through the circulatory system again

Question 2

Explain one advanatge of a double circulatory system

Answer 2

Blood is at a higher pressure in the systemic circulation, so blood flows faster, delivering nutrients and removing waste at a higher rate, more activity

Question 3

Describe 2 ways in which the structure of capillaries is related to their function

Answer 3

Microscopic blood vessels with walls only one cell thick,diffusion distance is very short. Rapid diffusion of materials between the blood and cells. Narrow diameter means they can have a large network inside tissues, meaning all cells are close to capillaries and can eaily recive oxygen and glucose, release waste products

Question 4

Explain how elastic tissue in the wall helps out to even out the pressure of blood flowing through artery

Answer 4

Elastic tissue can stretch as a result of a high blood pressure, recoil when blood pressure lowers again

Question 5

How do tissue fluid form

Answer 5

High hydrostatic pressue at the arteriole end,caused by ventricular sytosle, forces fluid out of the capillary into the tissues
Large plasma proteins remain behind the capillaries,lowering water potential and helping bring fluid back in. At venous end, water potential is greater than hydrostatic pressure, net inward movement of fluid
Tissue fluid not reabsorbed into the blood drains into the lymphatic vessels

Question 6

Explain the difference in the muscular walls of the left and right ventricle

Answer 6

Right ventricle only pumps blood to the lungs, thinner muscle wall
Left ventricle needs to pump blood to entire body
Thicker muscualr wall generates a large pressure during every contraction,pumped across longer distances

Question 7

State how many valves the heart has and state the name and function of the vale between the aorta and the left ventricle

Answer 7

4 valves

One of the semilunar valves prevent backflow of blood back into the heart from the aorta

Question 8

State which 3 phases make up the cardiac cycle

Answer 8

Atrial sytosle
Ventricular sytsole
Cardiac diastole

Question 9

Explain the events that occur during diastole

Answer 9

Elastic recoil causes both atria and the ventricles to relax , lowering the pressure within the chambers
Causese the blood in the pulmonary arteries and aorta to move backwards,closing the semi lunar valves
Low pressure in the atria helps draw blood into the heart,ready 4 next contraction

Question 10

Define diastole

Answer 10

Diastole is the relaxation of all muscles of the heart

Question 11

Define atrial systole

Answer 11

Occurs when both atria contract, SAN sends a wave of impulse across the atria to iniate this
Ensures the ventricles are completly full of blood for ventricular systole

Question 12

State which heart valves are open and which are closed during atrial systole

Answer 12

Atrioventricular valves are open, and the semilunar valves are closed

Question 13

Define ventricular systole

Answer 13

Occurs when both ventricles contract after the impulse is delayed at the AVN

Question 14

Describe the process of diastole

Answer 14

Blood fills the atria, returning from the lungs or body
Atrial pressure rises over ventricular pressure
Atrioventricular valves open
Blood moves into the ventricles
Artery pressure higher than ventricular pressure
Semi lunar valves close, making ‘Dub’ sound

Question 15

If the left ventricle wall thickens, the ventricle becomes stiff and is no longer able to pump the same amount of blood as it did under normal circumstances.
Explain the effect on the blood pressure in the main artery of the arm

Answer 15

Left ventricles becomes stiff,less blood than normal is pumped with each heartbeat heartbeat, leading to decrease in blood pressure

Question 16

Explain what happens during the ventricular systole phase of the cardiac cycle

Answer 16

Ventricles contarct
Causes both Atrioventricular valves to close, preventing blood moving backwards into the atria and the semilunar valves to open,pushing the blood up and out of the heart and into the pulmonary arteries and aorta

Question 17

Explain the cardiac cycle

Answer 17

1) Atrial pressure>ventricular pressure
2) Ventricular pressure> atrial pressure
3) Ventricular pressure> aortic pressure
4) Aortic pressure > ventricular pressure
5) Atrial pressure> ventricular pressure

Question 18

Describe the mechansim by whcih heart coordinates its contraction

Answer 18

SAN generates electrical impulse, create wave of excitation that travel through the muscle tissue of the atria, causing them to contract. Base of atria cannot conduct electrcity with the exception of the AVN, which delays the impulse and then lets its pass to the Purkyne fibre.
Impulses travel to the apex of the heart and contraction occurs from the bottom of the ventricle upwards

Question 19

Define electrocardiography

Answer 19

ECG Is the process of recording electrical activity of the heart
Over a period of time usinf electrodes placed over the skin

Question 20

Define atrial fibrilation

Answer 20

Atrial fibrilation is a heart that causes an irregular stimulation of the atria making them contract in an uncordinated manner,normally faster than ventricles

Question 21

Explain why the removal of CO2 from cells is essential

Answer 21

Waste product from respiration
CO2 diffuses into RBC and combines with water to form carbonic acid
Reaction catalysed by the enzyme carbonic anhydrase
Carbonic acid dissociates to form a H carbonate ion and a hydrogen ion in plasma, would increase the acidity (lowers the pH)
Damage cells and enzymes

Question 22

Describe how CO2 produced in tissues in transported in the blood to the lungs

Answer 22

CO2 in the tissue diffuses into tissue fluid. The tissue fluid moves back into the capillaries, becoming blood plasma.
Some of CO2 combines with haemoglobin, at the alveoli the CO2 is released, diffuses into the alveoli of the lungs

Question 23

Describe the removal of hydrogen carbonate ions in the blood

Answer 23

Carbonic acid dissociates to form hydrogen carbonate ions and hydrogen ion.
Hydrogen carbonate ions diffuse out of the cell and are transported around the body to the lungs. Chloride ions diffuse in to balance the change in charge from the loss of hydrogen carbonate ions. Chloride shift. Haemoglobin acts as a buffer by taking up the H ions to prevent the redblood cellw becoming too acidic. Combining of haemoglobin and H ions produces haemoglobnic acid

Question 24

If the partial pressure of Co2 increases, the dissociation curve for haemoglobin moves to the right. Explain the importance of this effect

Answer 24

At higher partial pressure of CO2, affinity of haemoglobin for oxygen is reduced. Therefore haemoglobin releases oxygen more readily at the same partial pressure of oxygen. Oxygen is releases to actively respiring tissues