4.4 Circulation

Question 1

What are the 4 chambers of the heart?

Answer 1

• Left + right ventricles.
• Left + right atria.

Question 2

What are the 4 main blood vessels?

Answer 2

• Pulmonary vein (lungs to left atrium).
• Aorta (left ventricle to body).
• Vena cava (body to right atrium).
• Pulmonary artery (right ventricle to lungs).

Question 3

What are the atrioventricular valves and what do they do?

Answer 3

• Mitral or tricuspid/bicuspid.
• Prevent backflow form ventricles to atria.

Question 4

What are the semilunar valves and what do they do?

Answer 4

• Pulmonary/aortic.
• Separate arteries from ventricles.

Question 5

What do valve tendons do?

Answer 5

• Prevent atrioventricular valves from turning inside out due to the pressure when heart contracts.

Question 6

What is the septum made of and what does it do?

Answer 6

• Muscle + connective tissues.
• Prevents oxygenated + deoxygenated blood from mixing.

Question 7

What did the coronary arteries do?

Answer 7

• Wrapped around heart to supply cardiac muscle w/ blood.

Question 8

Which side of the card is muscle is thicker?

Answer 8

• LHS because needed to withstand high pressure to pump blood to all tissues in body.

Question 9

What are the 3 types of circulatory system?

Answer 9

• Closed.
• Open single.
• Open double.

Question 10

What are 4 advantages of a double circulatory system?

Answer 10

• Conc. gradient maintained.
• Blood pressure to body tissues is higher.
• Blood pressure to lungs is lower (preventing damage).
• Organisms can develop larger bodies.

Question 11

The heart is referred to as myogenic what does this mean?

Answer 11

• It can stimulate its own contractions wo/ nervous stimulation.

Question 12

What are the 5 stages of myogenic contractions that occur in the heart?

Answer 12

• Depolarisation originates in sinoatrial node.
• Depolarisation spreads through atria causing atrial systole.
• Stimulates atriaventricular node.
• Delay for *batrial diastole** AVN spread depolarisation to bundle of His.
• Bundle of His splits into 2 branches - Purkinje Fibres - causes ventricular systole.

Question 13

What are the 3 stages of the cardiac cycle?

Answer 13

• Atrial systole.
• Ventricular systole.
• Cardiac diastole.

Question 14

What happens in atrial systole?

Answer 14

• Atria contract.
• Forces AV valves open + blood flows into ventricles.

Question 15

What happens in ventricular systole?

Answer 15

• Contraction of ventricles cause AV valves to close + semilunar valves to open.
• Blood leaves LV through aorta + RV through pulmonary artery.

Question 16

What happens in cardiac diastole?

Answer 16

• Atria + ventricles relax.
• Pressure inside heart chambers decreases.
• Caucasus semilunar valves to close to prevent back flow of blood.

Question 17

What are 3 functions of blood?

Answer 17

• Transport.
• Defence against pathogens.
• Formation of lymph + fluid tissue.

Question 18

What are 5 things that are transported in plasma?

Answer 18

• Digested food products (glucose, amino acids, etc.).
• Nutrient molecules.
• Hormones.
• Excretory products (CO2, urea, etc.).
• Heat.

Question 19

What is another name for red blood cells?

Answer 19

• Erythrocytes.

Question 20

What is another name for white blood cells?

Answer 20

• Leukocytes.

Question 21

What do erythrocytes transport?

Answer 21

• O2 and some CO2.

Question 22

How are erythrocytes specialised?

Answer 22

• Biconcave shape.
• No nucleus.
• Contain haemoglobin.

Question 23

What are 2 categories of leukocytes?

Answer 23

• Granulocytes.
• Agranulocytes.

Question 24

What are 3 examples of granulocytes?

Answer 24

• Neutrophils.
• Basophils.
• Eosinophils.

Question 25

What do neutrophils do?

Answer 25

- Phagocytosis.

Question 26

What do basophils do?

Answer 26

- Histamine - inflammation/allergic response.

Question 27

What do eosinophils do?

Answer 27

- Response to parasites, allergic reactions, inflammation + immunity.

Question 28

What are 2 examples of agranulocytes?

Answer 28

- Monocytes. - Lymphocytes.

Question 29

What are platelets made of?

Answer 29

- Fragments of megakaryocytes.

Question 30

What do platelets do?

Answer 30

- Involved in blood clotting.

Question 31

What is another word for blood clotting?

Answer 31

- Thrombosis.

Question 32

What are the 3 purposes of a blood clot?

Answer 32

- Prevents blood loss. - Prevents entry of disease-causing microorganisms. - Framework for repair.

Question 33

What is the step in the formation of a blood clot once a blood vessel has been damaged?

Answer 33

- Platelets attach to exposed collagen fibres.

Question 34

What happens in the formation of a blood clot and what must be present for this step?

Answer 34

- **Thromboplastin** (protein) released from platelets --> triggers conversion of **inactive prothrombin** (protein) to **active thrombin** (enzyme). - Calcium ions + vitamin K.

Question 35

What happens in the formation of a blood clot after thrombin (enzyme) has been formed?

Answer 35

- Catalyses conversion of **soluble fibrinogen** to **insoluble fibrin**.

Question 36

What happens in the formation of a blood clot once **insoluble fibrin** has been formed?

Answer 36

- Fibrin forms network of fibres --> platelets, RBCs + debris are trapped to form blood clot.

Question 37

What is atherosclerosis?

Answer 37

- Hardening of arteries caused by build-up of fibrous plaque called an **atheroma**.

Question 38

What 4 things can atherosclerosis lead to?

Answer 38

- **Angina** (chest pain due to restricted flow in coronary arteries). - **Stroke** (blocked artery in brain). - **Myocardial infarction** (heart attack due to blocking of coronary arteries). - **Aneurysm** (bulge in artery wall that can burst or form clot).

Question 39

What are the 5 steps in atherosclerosis?

Answer 39

- **Endothelium** lining arteries is damaged (cholesterol, smoking, high BP). - Inflammatory response ∴ WBCs move to site of damage. - Over time WBCs, cholesterol, Ca salts + fibres build up + harden forming **atheroma**. - Narrowing of artery --> restricts blood flow ∴ high BP which damages **endothelial lining**. - Process repeated.

Question 40

What are 9 examples of factors that lead to atherosclerosis?

Answer 40

- Genetics. - Age. - Diet. - Gender. - High blood pressure. - High cholesterol levels. - Smoking. - Physical inactivity. - Obesity.

Question 41

Blood clotting is a **cascade of events**, what does this mean?

Answer 41

- One signal sets off whole sequence of reactions, leading to important outcome.

Question 42

How is electrical activity measured in the heart?

Answer 42

- Through an electrocardiogram (ECG). - Electrodes attached to thorax + recording changes in potential differences.

Question 43

In an electrocardiogram, what does the P-wave represent?

Answer 43

- Atrial systole.

Question 44

In an electrocardiogram, what does the QRS wave represent?

Answer 44

- Ventricular systole.

Question 45

In an electrocardiogram, what does the T wave represent?

Answer 45

- Ventricular diastole.

Question 46

What is hypertension?

Answer 46

- high blood pressure.