Transport in animals

Question 1

Single Circulatory System

Answer 1

• Blood passes through the heart once in each
  circulation

Question 2

Double Circulatory System

Answer 2

• Blood passes through the heart twice in each
  circulation – once in the pulmonary (lung)
  circulation and then again through the
  systemic (body) circulation

Question 3

Closed Circulatory System

Answer 3

-Blood is pumped into a series of vessels;
blood flow is rapid and direction is controlled.
Organs are not bathed by blood

Question 4

Insects’ circulatory system?

Answer 4

OPEN Blood is pumped at low pressure by tubular heart into haemocoel

Question 4

Open Circulatory System

Answer 4

Blood is pumped into a cavity called a hemocoel where it surrounds the organs

Question 5

What are the characteristics of a closed circulatory system?

Answer 5

Blood pumped at higher pressure
Blood circulates through a continuous system of blood vessels

Question 6

fish vs mammals circulatory system

Answer 6

Fish have single circulations
Mammals have a double circulatory system

Question 7

What are the advantages of a double circulation system?

Answer 7

• Oxygenated and deoxygenated is separated
• High blood pressure maintained which leads to greater oxygenation
• Lower blood pressure to lungs means tissue fluid doesn’t build up which would reduce gas exchange efficiency

Question 8

Artery

Answer 8

Transport blood from the heart to the body tissue

Question 9

Vein

Answer 9

Transport blood from the body tissue back to the heart
- Contain semi-lunar valves to prevent backflow of blood

Question 9

Capillary

Answer 9

Facilitates the exchange of substances between the blood and body tissue
- One cell thick

Question 10

Blood pressure changes in the blood vessels

Answer 10

Aorta and arteries - highest pressure, a rhythmical rise and fall in pressure correspond to contraction and relaxation of ventricles.
Arterioles - Friction with the vessel walls causes a pressure drop. They can adjust their diameter to control blood flow
Capillaries- Have huge cross sectional surface area, this reduces pressure and slows blood flow.(allow exchange of substances)
Veins - The return flow to the heart is non rhythmical, pressure is low

Question 11

Describe the flow of blood through the heart

Answer 11

DEOXYGENATED BLOOD
- Vena Cava
- Right Atrium
- Tricuspid opens
- Right ventricle
- Tricuspid closes
- Semi lunar opens
- Pulmonary artery
- Lungs
OXYGENATED BLOOD
- Pulmonary vein
- Left atrium
- Bicuspid opens
- Left ventricle
- Bicuspid closes
- Semi lunar opens
- Aorta
- Body

Question 12

The cardiac cycle

Answer 12

• series of events which makes up one heartbeat
• Atrial systole, Ventricular systole, Ventricular diastole, diastole

Question 13

Atrial Systole

Answer 13

• Atria contracts
• blood flows through the atrio-ventricular valves into the ventricle
• Pressure developed during this contraction is not very great due to the thin atria walls
• Backflow prevented by the valves closing

Question 14

Ventricular Systole

Answer 14

• Ventricle contract (0.1s after atrial systole)
• Atria-ventricular valves close ( greater pressure in ventricles)
• Semi lunar in aorta and p.artery open
• Blood flows into arteries
• Generates greater pressure due to thick walls

Question 15

Ventricular diastole

Answer 15

• Heart muscles relax and pressure drops in ventricles
• Semi lunar valves snap shut to prevent backflow of blood from arteries

Question 16

Diastole

Answer 16

• The whole of he heart muscle relaxes
• Blood from the veins flows into the atria
• Cardiac cycle begins again

Question 17

Describe the pressure changes within the heart

Question 18

Arterioles

Answer 18

Smaller arteries that control blood flow from arteries to capillaries. Muscular layer is relatively thicker than in arteries and elastic layer is relatively thinner.

Question 19

Initiating the heart beat

Answer 19

• The heart beat is myogenic and initiates from within the heart itself
  1) The sinoatrial node (SAN) acts as a pacemaker and sends a wave of excitation across the atrium, stimulating contractions
  2) Thick connective tissue stops the wave from reaching the ventricle
  3) The wave is passed to the atrio-ventricular node (AVN) where it is delayed to allow the atria to complete contraction
  4) AVN transmits the wave of excitation down the bundle of His to the apex of the heart
  5) The impulse travels up the branches of the Purkinje fibres, stimulating ventricle contraction from the bottom up, ensuring all blood is pumped out

Question 20

What is an ECG and how can it be measured ?

Answer 20

The electrical activity that spreads through the heart during
the cardiac cycle can be detected using electrodes placed
on the skin and shown on a cathode ray oscilloscope. This is
called an electrocardiogram (ECG).

Question 21

Waves of an ECG

Answer 21

P = Depolarisation of the atria
corresponding to atrial systole.
Q, R, S = Spread of depolarisation through the ventricles resulting in ventricular systole.
T = Repolarisation of the ventricles resulting in ventricular diastole.

Question 22

Red blood cells and haemoglobin carrying oxygen

Answer 22

Red blood cells transport oxygen
- Haemoglobin has a high affinity for oxygen as each molecule can carry four oxygen molecules, forming oxyhaemoglobin.
- This reaction is reversible

Question 23

The Chloride Shift

Answer 23

1) CO2 diffuses into a Red blood cell (RBC)
2) CO2 combines with H2O catalysed by enzyme carbonic
anhydrase, forming carbonic acid.
3) Carbonic acid dissociated into H+ ions and HCO3 ions diffuse out of the RBC into the blood plasma
4) Chloride ions diffuse (facilitated diffusion) into the RBC
to maintain electrochemical neutrality – the chloride shift
5) H+ bind to oxyhaemoglobin, reducing its affinity for oxygen. This is the Bohr effect
6) Oxygen is released from the haemoglobin.
7) Oxygen diffuses from the RBC into the plasma and body
cells.

Question 24

How is Tissue Fluid formed?

Answer 24

• At the arterial end of the capillary bed, hydrostatic
  pressure is higher than osmotic pressure.
• Water and small soluble molecules are forced through
  the capillary walls, forming tissue fluid between the cells.
• Proteins and cells in the plasma are too large to be forced out
• Due to reduced volume of blood and friction, blood
  pressure falls and it moves through the capillary
• At the venous end of the capillary bed, osmotic pressure
  of the blood is higher than the hydrostatic pressure.
• Most of water from tissue fluid moves back into capillaries (down its water potential gradient). The
  remainder of the tissue fluid is returned to the blood via
  lymph vessels.

Question 25

Describe the oxygen dissociation curve - THE BOHR SHIFT

Answer 25

line a = shows haemoglobin has high affinity for oxygen at high partial pressure ( in the lungs) and releases it readily in lower partial pressure (respiring tissue)

line b = Where co2 is present the Bohr Shift occurs and the curve moves to the right, meaning haemoglobin has a lower affinity for oxygen, releasing it more readily. Helpful for respiring tissue