Cardiovascular system 2 Flashcards
Blood flow (heart);
Stage 1; Deoxygenated blood from the superior and inferior vena cava arrive in the right atrium (3mm thick)
It pumps blood through tricuspid valve into the right ventricle (5mm thick)
Stage 2; Right ventricle contracts & pumps the deoxygenated blood through the pulmonary valve and into the pulmonary trunk (which divides the left & right pulmonary arteries)
Stage 3: The blood flows through the lungs where gas exchange occurs
Stage 4: Blood (now oxygenated) returns to the left atrium (3mm thick) via the pulmonary vein
Stage 5; The left atrium pumps oxygenated blood through the mitral / bicuspid valve into the left ventricle (10-15mm thick)
Stage 6: The left ventricle contracts & pumps oxygenated blood through the aortic valve into the ascending aorta. Some of the blood the aorta flows into the coronary arteries which carry blood to the heart wall
Cardiac output
The volume of blood being pumped out by the heart per minute. On average 5L per minute. Key definitions = systole, diastole, tachycardia, bradycardia
Cardiac output; blood pressure
The pressure exerted by circulating blood on the blood vessel walls.
Diastolic - Period of relaxation when the heart fills with blood
Systolic - The force that drives blood out of the heart (contraction)
Cardiac output; rate
Bradycardia; Resting heart rate under 60 bpm (brady = slow)
Tachycardia; Resting heart rate of over 100 bpm (tachy = rapid)
Cholesterol
A vital compound for cell structure and function. It is in every cell. Functions inc. cell membrane integrity, Vit D & calcium metabolism, sex hormone
Circulation
2 types of circulation; systemic circulation and pulmonary circulation;
Circulation (pulmonary)
Blood from the heart to the lungs and back to the heart (pulmonary = meaning lungs)
Circulation (systemic)
Blood from the heart is distributed around the body before returning to the heart (systemic = relating to body systems/entire body)
Conduction system of the heart
System of nerves that help the heart contract. 5 steps;
1) sinoatrial node (SA node),
2) Atrioventricular node (AV node),
3) Atrioventricular bundle (Bundle of His),
4) Right & left bundle branches,
5) Purkinje fibres
Step 1) Sinoatrial node (SA node);
The pacemaker of the heart – sets rate and rhythm. Initiates cardiac conduction in right atrial wall. Each nerve impulse from SA node propagates through each atrium causing atrial contraction
Step 2) Atrioventricular node (AV node); A relay station - conducts impulses at a slightly lower rate to allow atria to finish contracting. Located in the bottom right of intertribal septum
Step 3; Atrioventricular bundle (Bundle of His); Only site where nerve impulses can conduct from atria to ventricles
Step 4) Right & left bundle branches; From the bundle of his, the nerve impulse enters the left & right bundle branches, which extend the interventricular septum towards apex of the heart
Step 5) Purkinje fibres; The purkinje fibres conduct nerve impulse beginning at the apex of heart, up the remainder of ventricular myocardium = ventricular contraction
Contraction (of the heart)
The myocardium performs periodic contractions through a network of cardiac fibres that are self-excitable (autorhythmic)
Ductus arteriosum
A temporary blood vessel (during foetal life) called the ductus arteriosum shunts the blood from the pulmonary trunk to the aorta. Closes after birth to form ligamentum arteriosum (ductus = duct/tube, arteriosum = artery)
Foramen ovale
A depression called the fossa ovalis (within the interatrial septum is).Previously called foramen ovale in foetal development where it shunts blood from right atrium - left atrium, to bypass lungs (foramen=hole, fossa=shallow depression)
Heart layers
Fist sized muscular organ that contracts to pump blood around the body. Has three layers; endocardium, myocardium, pericardium
Layers; Endocardium
Innermost layer, thin layer of endothelium overlying a thin layer of connective tissue. Provides a smooth lining for the heart chambers & covers heart valves
Layers; Myocardium
Middle & thickest layer, autorhythmic cardiac muscle (striated & involuntary), makes up 95% of the heart. Functions to pump blood out of the heart
Layers; Pericardium
Outer layer of heart, thin double layered membrane. Contains fibrous pericardium that attaches to the diaphragm & inner serous pericardium. Functions to keep heart in position within the thorax & allow free movement during contractions
Lipoproteins;
LDL & HDL
Low density lipoproteins (LDL). Carry 75% total cholesterol in blood, carrying it from the liver to cells of the body. In excess can deposit cholesterol in arteries
High density lipoproteins (HDL). Remove excess cholesterol from body cells & blood & transport it to the liver. Prevent accumulation of cholesterol in blood