**4.4 Circulation** Flashcards
What are the 4 chambers of the heart?
- Left + right ventricles.
- Left + right atria.
What are the 4 main blood vessels?
- Pulmonary vein (lungs to left atrium).
- Aorta (left ventricle to body).
- Vena cava (body to right atrium).
- Pulmonary artery (right ventricle to lungs).
What are the atrioventricular valves and what do they do?
- Mitral or tricuspid/bicuspid.
- Prevent backflow form ventricles to atria.
What are the semilunar valves and what do they do?
- Pulmonary/aortic.
- Separate arteries from ventricles.
What do valve tendons do?
- Prevent atrioventricular valves from turning inside out due to the pressure when heart contracts.
What is the septum made of and what does it do?
- Muscle + connective tissues.
- Prevents oxygenated + deoxygenated blood from mixing.
What did the coronary arteries do?
- Wrapped around heart to supply cardiac muscle w/ blood.
Which side of the card is muscle is thicker?
- LHS because needed to withstand high pressure to pump blood to all tissues in body.
What are the 3 types of circulatory system?
- Closed.
- Open single.
- Open double.
What are 4 advantages of a double circulatory system?
- Conc. gradient maintained.
- Blood pressure to body tissues is higher.
- Blood pressure to lungs is lower (preventing damage).
- Organisms can develop larger bodies.
The heart is referred to as myogenic what does this mean?
- It can stimulate its own contractions wo/ nervous stimulation.
What are the 5 stages of myogenic contractions that occur in the heart?
- 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.
What are the 3 stages of the cardiac cycle?
- Atrial systole.
- Ventricular systole.
- Cardiac diastole.
What happens in atrial systole?
- Atria contract.
- Forces AV valves open + blood flows into ventricles.
What happens in ventricular systole?
- Contraction of ventricles cause AV valves to close + semilunar valves to open.
- Blood leaves LV through aorta + RV through pulmonary artery.
What happens in cardiac diastole?
- Atria + ventricles relax.
- Pressure inside heart chambers decreases.
- Caucasus semilunar valves to close to prevent back flow of blood.
What are 3 functions of blood?
- Transport.
- Defence against pathogens.
- Formation of lymph + fluid tissue.
What are 5 things that are transported in plasma?
- Digested food products (glucose, amino acids, etc.).
- Nutrient molecules.
- Hormones.
- Excretory products (CO2, urea, etc.).
- Heat.
What is another name for red blood cells?
- Erythrocytes.
What is another name for white blood cells?
- Leukocytes.
What do erythrocytes transport?
- O2 and some CO2.
How are erythrocytes specialised?
- Biconcave shape.
- No nucleus.
- Contain haemoglobin.
What are 2 categories of leukocytes?
- Granulocytes.
- Agranulocytes.
What are 3 examples of granulocytes?
- Neutrophils.
- Basophils.
- Eosinophils.
What do neutrophils do?
- Phagocytosis.
What do basophils do?
- Histamine - inflammation/allergic response.
What do eosinophils do?
- Response to parasites, allergic reactions, inflammation + immunity.
What are 2 examples of agranulocytes?
- Monocytes.
- Lymphocytes.
What are platelets made of?
- Fragments of megakaryocytes.
What do platelets do?
- Involved in blood clotting.
What is another word for blood clotting?
- Thrombosis.
What are the 3 purposes of a blood clot?
- Prevents blood loss.
- Prevents entry of disease-causing microorganisms.
- Framework for repair.
What is the step in the formation of a blood clot once a blood vessel has been damaged?
- Platelets attach to exposed collagen fibres.
What happens in the formation of a blood clot and what must be present for this step?
- Thromboplastin (protein) released from platelets –> triggers conversion of inactive prothrombin (protein) to active thrombin (enzyme).
- Calcium ions + vitamin K.
What happens in the formation of a blood clot after thrombin (enzyme) has been formed?
- Catalyses conversion of soluble fibrinogen to insoluble fibrin.
What happens in the formation of a blood clot once insoluble fibrin has been formed?
- Fibrin forms network of fibres –> platelets, RBCs + debris are trapped to form blood clot.
What is atherosclerosis?
- Hardening of arteries caused by build-up of fibrous plaque called an atheroma.
What 4 things can atherosclerosis lead to?
- 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).
What are the 5 steps in atherosclerosis?
- 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.
What are 9 examples of factors that lead to atherosclerosis?
- Genetics.
- Age.
- Diet.
- Gender.
- High blood pressure.
- High cholesterol levels.
- Smoking.
- Physical inactivity.
- Obesity.
Blood clotting is a cascade of events, what does this mean?
- One signal sets off whole sequence of reactions, leading to important outcome.
How is electrical activity measured in the heart?
- Through an electrocardiogram (ECG).
- Electrodes attached to thorax + recording changes in potential differences.
In an electrocardiogram, what does the P-wave represent?
- Atrial systole.
In an electrocardiogram, what does the QRS wave represent?
- Ventricular systole.
In an electrocardiogram, what does the T wave represent?
- Ventricular diastole.
What is hypertension?
- high blood pressure.
