4. cardiovascular system Flashcards
role of cardiovascular system?
= transport system responsible for delivering oxygen, hormones, carrying waste products and nutrients around the body
- Heart acts as a pump to push the blood around the body, the blood transports oxygen and waste around the body and the blood vessels contain the blood and maintain the pressure
- Any disruptions in these three components can lead to the development of coronary hear disease
Cellular changes that occur in cardiac muscles in response to increase workload?
Increased workload = increases the affects on the heart
- when there is increased workload the muscles need more oxygen = heart muscles pump harder
- muscles send signal saying they need more oxygen - heart pumps harder and you breathe faster to get more oxygen into lungs
Define the term shock and explain how it may develop?
Shock = the supply of blood to the tissue is inadequate to meed the metabolic demand of the body
- all types of shock result in acute circulatory failure which causes tissue hypoperfusion which leads to cellular hypoxia which may lead to tissue damage/ organ failure
- Shock can result from heart failure, fluid loss, sepsis or an allergic reaction
Homeostasis
= the body’s ability to maintain stable internal conditions despite the changes to external environment
main systems that control homeostasis?
Most commonly, the nervous and endocrine systems restore homeostasis in the body.
- Nervous system acts by sending electrical signals (nerve impulses/action potentials) to organs to counteract the imbalance
- Glands in the Endocrine system secrete hormones into the blood.
- nerve impulses - rapid change, hormones = slower change
Feedback systems?
- stimulus
- Receptor
- afferent pathway
- control centre (brain
- efferent pathways
- effector
difference between positive and negative feedback?
Negative feedback reverse a change in a controlled condition.
Positive feedback strengthen or reinforce a change in a controlled condition
How does the body maintain blood pressure in a person with sever bleeding
Adequate blood pressure is needed for blood flow and hence the transport of all nutrients and wastes to and from regions such as.
- Three negative feedback pathway loops for blood pressure = indicate that three different processes must be active to keep blood pressure sufficient
- When sodium is retained by the kidneys so that it remains in the blood instead of exiting the boding in the urine, water is also retained = increase in blood volume and corresponding increase in blood pressure
Three classifications of anemia?
- microcytic
- normocytic
- macrocytic
Causes of microcytic anemia ?
= small pale RBC, normal or low RBC count
causes:
- iron deficiency
- thalassemia trait - genetic defect in hb, alpha or beta chains of hb affected
Causes of Normocytic anemia?
= cells normal in size and colour but low RBCC
causes:
- blood loss
- haemolytic anemia - immune complexes, faulty heart valve
- sickle cell disease - malaria
Causes of macrocytic anemia?
=. large RBC, low RBC, no central pallor
- Megaloblastic anaemia – folate or B12 deficiency, may be genetic
- Aplastic anaemia: bone marrow failure = abundant red bone marrow in femur of young child compared to apparent absence of marrow in femur of child who died from aplastic anaemia
What is a myocardial infarction?
=. occurs when there. is an obstruction in the coronary artery
- resulting in lack of blood supply (ischemia) and inadequate oxygen (hypoxia) to the heart muscles
= tissue death (infarction) of heart muscles, compromising or stopping the heart functioning
What can cause a myocardial infarction?
- Atherosclerosis : narrowing of the coronary arteries, due to a build-up of cholesterol and fat (plaque) in the arterieso Build up cause’s arteries to become harder and more restricted, decreasing the blood flow through the artery
o If plaque breaks off it causes occlusion in artery = stopping blood supply to heart = ischemia, hypoxia and cell death – a myocardial infarction - Blood clot (thrombosis) = blocking the blood flow
- Coronary artery disease
Heart failure
= defined as cardiac impairment with inability to fill or eject blood volume
- thus the heart can no longer pump enough blood around the body
- cam occur on left ventricular failure (congestive heart failure) and right sided heart failure
Pathophysiology and effect on the body of left sided heart failure
= left ventricle no longer pumps enough blood around the body
- Therefore, blood builds up in the pulmonary veins
- Causes shortness of breath and trouble breathing
- More common
- Effect: dyspnoea, orthopnoea, fatigue, decreased urine, oedema
- Physical: hypotension or hyper
Pathophysiology and effect on the body of right sided heart failure
= right ventricle is too weak to pump enough blood to the lungs
- Causes blood to build up in the veins that carry blood from the organs and tissues back to the heart
- Increased pressure in veins can push out of the veins into surrounding tissues (backs up into veins)
- Leads to build-up of fluid in legs
- Effect: swelling in legs, groin, abdomen, ankles, in GI tract and liver
what is a blood clot and what factors map promote a blood clot?
= meshwork of protein strands that stabilises the platelet plug (platelets)
- Stands are made of fibrin produced by secondary homeostasis (coagulation)
- Coagulation cascade enzymes or coagulation factors are produced by the liver and are circulating in the blood
- Coagulation factors activate each other in a sequence of complex restriction = resulting in series of reactions to form a blood clot
- Vessel injury initiates coagulation which triggers clot formation
What are the risk factors of a blood clot?
- obesity
- pregnancy
- immobility
- smoking
- oral contraceptives
- certain cancers
- trauma
what is stable angina?
= get angina (chest pain) during moderate physical activity or when you are pushing yourself physically
- symptoms go away with rest and or medication
Pathophysiology of stable angina?
- Occurs when the heart muscle doesn’t get enough oxygen that it needs to function properly
- When you exercise your heart works harder however the heart cannot supply enough oxygen for the hard working
Modifiable and modifiable factors of a myocardial infarction and how does it contribute to its development?
Modifiable
- High blood pressure = increases risk of heart disease, heart attack and stoke
- High blood cholesterol
- Diabetes
- Obesity = physical inactivity
- Smoking
non modifiable
- age
- ethnicity
- genetics
what is vein thrombosis
= blood clots which have formed in the vein
Pathophysiology of vein thrombosis
- vessel injury initiates coagulation which triggers clot formation
- Can break off and
become an embolism - Is clotting of the blood deep in the vein of an extremity or pelvis
o Primary cause of pulmonary embolism - Results from condition that impair venous return lead to endothelial injury or dysfunction and cause hypercoagulability
Pulmonary embolism
= a thrombus that occludes pulmonary arterial circulation
- Usually begins as a thrombus in the deep veins of the pelvis or lower limbs
- A small part of the thrombus (an embolism) breaks away and travels to the lungs
Pathophysiology of pulmonary embolism
- Impact depends on the extent of the pulmonary blood flow obstruction
What is virchow’s triad?
= three factors that generally lead to the development of DVT
- function is to demonstrate the underlying physiology that drives the formation of venous thrombus
- hypercoagulability
- venous stasis
- venous injury
Outline the relationship between virchow’s triad and DVT
- Hypercoagulability: can occur due to pregnancy, use of oral contraceptive meds, cancer, chemo drugs and inherited thrombophilia
- Venous stasis
o Caused by immobilisation, obesity and heart disease)
o Most likely to occur with patients with atrial fibrillation, valvular heart disease; prolonged immobility
o Blood flow slows through vascular beds, flow reduces and the natural anticoagulant properties from interaction with surface proteins are affected, resulting in thrombi production - venous injury (endothelia damage)
o Especially endothelial damage (caused by surgery, trauma, previous DVTs)
o Damage to endothelial wall of a vessel alters the dynamics of blood flow
o Can be a result from smoking, chronic high blood pressure and atherosclerotic disease
what are the changes experienced by the pulmonary circulation due to a pulmonary embolism
= pulmonary embolism alters pulmonary blood flow: effect is determined by the size of thee occlusion
- massive occlusion: an embolus that occludes a major portion of the pulmonary circulation (i.e. main pulmonary artery embolus)
- embolus with infarction: an embolus that is large enough to cause infarction (death) of a portion of lung tissue
- embolus without infarction: an embolus that is not severe enough to cause permanent lung injury
- multiple pulmonary emboli: may be chronic or recurrent
Affect a pulmonary embolism would have on the heart and systemic circulation
If there if a clot in the lungs it affects the heart and the brain
-heart :the blood is no longer oxygenated when it is sent back to the heart thus the heart is not receiving oxygen to pump to the body.
o Ventilatory rate and heart rate are elevated to compensate for the low oxgen level and increased work of breathing
-brain : as the heart cannot pump oxygenated blood to the brain the brain cannot send messages as it needs oxygen to function = no feedback mechanism
Pulmonary embolism (blood clot in the lungs) : if the blood clot travels from the blood vessels in legs to the lungs = develop pulmonary oedema
