Circulatory System

Question 1

How do small aquatic invertebrates obtain oxygen?

Answer 1

Diffusion through gastrovascular cavities.

Question 2

Describe what open circulatory systems are and which organisms have them?

Answer 2

• No distinction between tissue fluid and blood = haemolymph
• Fluid squeezed through intercellular spaces by animal movement + muscular pump (tubular heart)
• e.g. insects.

Question 3

Describe closed circulatory systems.

Answer 3

• Blood separate from blood
• Muscular pump (heart)
• Some blood components never leave vessels.

Question 4

What are the advantages of circulatory systems?

Answer 4

• Blood flows through vessels than intracellular spaces
• Possible to selectively direct blood to specific areas
• Transport facilitating molecules can be kept within vessels
  > Support higher level of metabolic activity.

Question 5

What are the components of blood?

Answer 5

• Red blood cells
• White blood cells
• Platelets
• Plasma.

Question 6

Describe red blood cells.

Answer 6

• Otherwise known as Erythrocytes
• Biconcave
• Have haemoglobin.

Question 7

Describe the structure of haemoglobin.

Answer 7

• 2 alpha subunits
• 2 beta subunits
• Each has a haem (Fe) group
• Cooperative binding of oxygen.

Question 8

What blood vessels make up the vascular system?

Answer 8

• Arteries
• Veins
• Capillaries.

Question 9

Describe arteries and arterioles.

Answer 9

• Move blood away from heart
• Usually oxygenated
• Walls made of elastin and smooth muscle.

Question 10

Describe veins and venules.

Answer 10

• Take blood to heart (except hepatic portal vein (liver))
• Usually deoxygenated
• Low pressure blood - moving against gravity.

Question 11

Describe capillaries.

Answer 11

• Thin permeable walls
• Adjacent to all body cells
• Small diameter but huge number = slow blood flow
• Leaky - fenestrations
• Blood pressure squeezes out water and some solutes on arterial side
• Proteins and other solutes create osmotic potential - draws water back in on venous side
• Differentially selective.

Question 12

Describe lymphatic vessels.

Answer 12

• Some tissue fluid not drawn back into capillaries
• System of blind-ended vessels
• Merge into larger vessels, drain into superior vena cava
• Lymph nodes
• Skeletal muscle movement.

Question 13

Define atria.

Answer 13

Smaller chamber that blood initially returns to.

Question 14

Define ventricles.

Answer 14

Larger chamber that collects blood and pressurises it.

Question 15

Define pulmonary artery.

Answer 15

Takes blood to lungs.

Question 16

Define pulmonary vein.

Answer 16

Returns blood from lungs.

Question 17

Define aorta.

Answer 17

Takes blood to body.

Question 18

Define Vena cava.

Answer 18

Returns blood from body.

Question 19

What are pace maker cells?

Answer 19

Cells found in cardiac muscle which ensures the heart beats at the correct rhythm at that each cardiac muscle cells coordinates with each other i.e. beats at the same time.

Question 20

How do pacemaker cells create their own action potentials?

Answer 20

Leaky membranes allow sodium to move in to cells and potassium to move out without any external triggers.

Question 21

Define diastole.

Answer 21

Relaxing of the heart.

Question 22

Define systole.

Answer 22

Compressing of the heart.

Question 23

Define end-diastolic volume (EDV)?

Answer 23

Maximum amount of blood in ventricles at end of ventricular relaxation.

Question 24

Define isovolumic ventricular contraction.

Answer 24

First phase of ventricular contraction pushes AV valves closed but does not create enough pressure to open semilunar valves.

Question 25

Define end-systolic volume (ESV)?

Answer 25

Minimum amount of blood in ventricles.

Question 26

What does a blood pressure reading tell you?

Answer 26

Systolic blood pressure/diastolic blood pressure.

Question 27

What is the sinotrial node (SAN)?

Answer 27

• Cheif pacemaker cell in heart
• Beats fastest
• Controls heart beat.

Question 28

What is the atrioventricular node.

Answer 28

• Can take over temporarily if sinotrial node stops working properly
• Beats slower than sinotrial node.

Question 29

What does the bundle of His do?

Answer 29

Located in atrioventricular septum of heart (area which doesn’t conduct). Slows the contractive impulse from atria to ventricles to allow two step contraction process.

Question 30

What is a block?

Answer 30

Impulses are not getting through bundle of his.

Question 31

Define Arrhythmia.

Answer 31

No regular heart rhythm.

Question 32

Define Tachycardia.

Answer 32

Heart rate is too fast.

Question 33

Define fibrillation.

Answer 33

Atria are contracting irregularly whilst ventricle contract at a normal rhythm.

Question 34

Describe control and regulation of heart rate.

Answer 34

• Autoregulation e.g. O2, lactate, CO2
• Neural/endocrine regulation
• Kidney reabsorption of water.

Question 35

Describe the heart structure of fish.

Answer 35

• Two chambers - one atrium one ventricle
• Low pressure in aorta
• Skeletal muscle helps pump.

Question 36

Describe the heart structure of amphibians.

Answer 36

• Three chambers: two atria one ventricle
• Minor mixing of oxygenated and deoxygenated blood
• High pressure in aorta.

Question 37

Describe the heart structure of reptiles.

Answer 37

• Threeish chambers: 2 atria one ventricle
• Switch lung supply on and off
• 2 aortas.