The Cardiovascular system Flashcards
What is the apex of the heart?
Formed from the tip of the left ventricle
What is the base of the heart?
opposite to apex and it is the upper and posterior margin of the heart, broader & flat like the base of a pyramid
What is the pericardium?
It is a triple-layered bag that surrounds and protects the heart
It confines the heart to its position to the centre of the thoracic cavity
Epicardium - outer most layer, tough, fibrous, inelastic
Myocardium (middle layer) - cardiac muscle makes the main bulk of the heart (involuntary, striated)
Endocardium (inner layer) - thin layer of endothelium that provides the smooth lining for the inside of the heart and covers the valves of the heart
What are the functions of valves?
Prevent backflow from the arteries into the ventricles
The closure of the semilunar valves causes the second heart sound (S2)
List the kinds of valves
- Atrioventricular (AV) valves
- Tricuspid (RHS)
- Bicuspid (mitral) (LHS)
What is the cardiovascular system?
→ Network of blood vessels
→ Extend between heart and peripheral tissues
→ Arteries (efferent vessels) -Carry blood away from heart -Elastic (conducting) arteries -Muscular (distributing) arteries
What is a sinoatrial node?
Located on posterior wall of right atrium. Contain pacemaker cells which establish heart rate
What is the atrioventricular node?
located on junction between atria and ventricles on the floor of the right atrium
What is an elecrocardiogram?
Recording of the electrical events in the heart
What is the P wave?
Depolarisation of atria and atrial contraction
what is the QRS complex?
Ventricle depolarisation. Electrical signal is strong because the ventricular muscle is much bigger. It is more complex also because of the pathway through which the impulse spreads in the ventricles
What is a T wave?
Ventricular repolarisation. Atrial repolarisation takes place during vent depolar and is masked by the QRS
What is blood pressure?
Blood pressure (BP) is the pressure exerted by circulating blood upon the walls of blood vessels
Usually refers to the arterial pressure in the systemic circulation
What factors affect cardiovascular pressure?
-Vessel diameter
-Total cross-sectional area
-Vessel pressures
-Velocity of blood flow
What is hypertension?
-abnormally high BP
-Increases the risk of heart attack, heart failure, kidney disease, stroke or dementia
-120/80 mmHg or slightly lower is normal
-Over 140/90 mmHg is abnormal
-Can be treated with ACE inhibitors or Ca channel blockers
What is hypotension?
-abnormally low BP
-<90/60 mmHg
-No medication
-Limit symptoms
Hormone regulation of blood pressure
-released by pituitary gland in response to decrease in blood volume
-Causes vasoconstriction elevating BP
What is the CV response to exercise?
-Extensive vasodilation occurs, arteries and veins dilate, helping blood flow quickly
-Venous return increases
-Skeletal muscle contractions force blood along veins
-Cardiac output increases
-With moderate exercise, blood flow to non-essential tissues decreases
-Skeletal muscle blood flow increases significantly
-Brain blood flow remains relatively constant
-Skin blood flow increases to reduce body temperature
What is the cardiovascular response to hemorrhaging?
Initial increase in cardiac output and peripheral venoconstriction
- Short-term rise in BP
Venoconstriction in organs: heart and brain are prioritised
Mobilises venous reserve and increases venous return
-Venoconstriction reduces volume of blood in venous system and increases volume in arteries and capillaries. Keeps blood volume within arteries and capillaries near normal despite significant blood loss
Constriction of veins in liver, skin and lungs redistributes a significant proportion of the total blood volume. Blood flow to delicate organs such as brain can be increased or maintained after blood loss
What is myocardial infarction?
MI or heart attack
Part of coronary circulation is blocked and cardiac muscle cells die
Non-functional area called infarct
