cardiovascular system/disorders Flashcards
function of cardiovascular system
A closed system of the heart and blood vessels
– The heart pumps blood
– Blood vessels allow blood to
circulate to all parts of the
body
• The function is to deliver oxygen and nutrients and to
remove carbon dioxide and other waste products
Systemic circulation
• Blood flows from the left side of the heart through the body tissues and back to the right side of the heart
Pulmonary circulation
• Blood flows from the right side of the heart to the lungs and back to the left side of the heart
The Heart: Valves
Allow blood to flow in only one direction to prevent
backflow
Atrioventricular (AV) valves —between atria and ventricles • Left AV valve or Bicuspid or Mitral valve (left side of heart) • Right AV or Tricuspid valve • (right side of heart)
Semilunar valves—between ventricle and artery
• Pulmonary semilunar valve (between right atrium & pulmonary artery)
• Aortic semilunar valve (between left atrium and aorta)
- The AV valves are open during heart relaxation and
closed when the ventricles contract
• The semi-lunar valves close during heart relaxation
and open when the ventricles contract
flow of the heart (simple)
- deoxygenated blood into superior/interior vena cava
- into right atrium
- into tricuspid valve
- into right ventricle
- passes through the pulmonary semilunar valve into the pulmonary trunk
- into pumlmonary arteries (left right) into lungs (oxygenated)
- into left atrium
- through bicuspid valve
- left ventricle
- aorta to the body
Blood Pressure (BP)
• Pressure that the blood exerts against the inner
walls of the blood vessel
– Systolic—pressure at the peak of ventricular
contraction
– Diastolic—pressure when ventricles relax
– Write systolic pressure first and diastolic last (120/80
mm Hg)
• Pressure in blood vessels decreases as distance
from the heart increases
Blood pressure is related to cardiac output (CO) and
peripheral resistance (PR)
PR is peripheral resistance, or the amount of friction blood encounters as it flows through vessels
CO is the amount of blood pumped out of the left ventricle per minute
BP = CO x PR
Narrowing of blood vessels (atherosclerosis or sympathetic nervous system) and increased blood volume increases PR
Factors that effect blood pressure:
Autonomic nervous system
• sympathetic nerves-causes vaso-constriction except in brain and heart
• Increases BP
Renal factors
• Regulation by altering blood volume (excrete more or less water)
• Release renin when BP is low →vasoconstriction and water retention
Blood gases
• Rising CO2 levels cause increased BP thus increasing blood supply to tissues
Temperature
• Heat has a vasodilating effect
• Cold has a vasoconstricting effect
Chemicals
• Various substances can cause increases or decreases
• eg. Adrenalin, nicotine increase BP; alcohol and
histamines decrease BP
vasocontriction
the constriction of blood vessels, which increases blood pressure.
vasodilation
the dilatation of blood vessels, which decreases blood pressure.
electro conduction system (SA node important)
-Contraction is initiated by Sinoatrial node = SA node (“pacemaker”), is in the right atrium
- Atrioventricular node = AV node, (gatekeeper) is at the
junction of the right atria and right ventricle
- Atrioventricular bundle = AV bundle (bundle of His), is in the interventricular septum
- Bundle branches are in the interventricular septum
- Purkinje fibres spread within the ventricle wall muscles
• Impulse spreads to the AV node then the atria contract.
- The AV node is also known as the Gate keeper. It controls the Tricuspid and Bicuspid valves opening and Closing. Allowing for filling and preventing backflow back to atria
• At the AV node, the impulse passes through the AV bundle (Bundle of His), Left and Right bundle branches,and Purkinje fibres and ventricles contract through impulse
veins structure and function
•Lumens of veins are larger. Larger veins. Have valves to prevent backflow.
•Superior and inferior venae cavae – enter right atrium •Pulmonary veins (four) – Enter left atrium
artery function and structure
•Walls of arteries are the thickest (especially smooth muscle layer) holding more pressure •Aorta – Leaves left ventricle •Pulmonary arteries – Leave right ventricle
Thrombus
• Formation of a blood clot inside a blood vessel
• Reduces or blocks blood flow to tissues
• Risk factors include slow blood flow, immobility,
compression, atherosclerosis,dehydration, pregnancy
Embolus
• part of the thrombus that dislodges
• The blocking of a blood vessel by any material (thrombus, air, fat) that moves through the blood
• Causes stroke, heart attack, gangrene, pulmonary
embolism
myocardial infarction (MI) + s&s
or heart attack occurs when a coronary artery is totally obstructed leading to prolonged ischemia and cell death.
Signs and symptoms: persistent crushing chest pain which may radiate down the left arm, followed by nausea, diaphoresis, SOB, pallor and rapid, weak
pulse. Often anxiety and sense of impending doom. Jaw pain may also be present
- not relived by meds
- caused by atherosclerosis, with thrombus attached
