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
heart failure (often referred to as Congestive Cardiac Failure (CCF) or congestive)
Heart Failure (CHF) is a chronic condition which occurs when the heart is unable to pump sufficient blood to meet the metabolic needs of the body • Can be both sides of the heart or just the left (left Ventricular failure) or right (right ventricular failure)
- Often occurs as a secondary complication: may develop after a MI, in response to chronic hypertension, diabetes mellitus or valve defect or inflammatory heart disease
- Initially left or right side cannot pump effectively but this eventually causes failure of the other side
left sided heart failure (LVF = Left Ventricular Failure)
- The right side continues to pump blood but the left side is unable to eject all of the blood into the systemic circulation.
- Back up of blood occurs through pulmonary veins back into lung tissue
- Pulmonary oedema occurs: the blood vessels in the lungs become swollen with blood and the pressure in
them increases forcing fluid to leak through engorged
capillaries into alveoli.
S&S
Symptoms of dyspnoea, orthopnea, pulmonary crackles, cough, fatigue, palpitations, haemoptysis
right sided heart failure (RVF = Right Ventricular Failure)
Right side cannot pump blood effectively to lungs
• Commonly due to LVF or pulmonary embolism
• Causes blood volume to increase in systemic circulation (back up in the peripheral veins) and pressure increases so that fluid leaks in to interstitial spaces
• The congestion in the venous system affects liver, spleen and kidneys
• Causes peripheral congestion and oedema (sacrum, feet and ankles), distended jugular veins, abdominal
distension, fatigue, palpitations
Ventricular fibrillation (VF)
• Medical emergency - cant eject the blood
• Rapid quivering of ventricles without ejecting blood
• Cause is usually myocardial ischaemia or infarction or
untreated VT
• Symptoms could include no pulse, BP or respiration’s,
unresponsive
Management
• CPR
• Defibrillation
oedema
swelling caused by excess fluid trapped in your body’s tissues.
- Swelling or puffiness of the tissue directly under your skin, especially in your legs or arms
- Stretched or shiny skin
- Skin that retains a dimple (pits), after being pressed for several seconds
- Increased abdominal size
why does dvt need prompt treatment
Left untreated can have the potential to cause a pulmonary embolus (clot in lungs)
signs and symptoms of internal bleeding
low bp increased hr reduced urine output sob haematuria headache confusion
atrial fibrillation (AF)
quiver instead of contracting which causes ventricles to contract (HR) irregularly between 100-180bpm
