Cardiovascular Flashcards
What effects pulse pressure?
PP is directly proportional to stroke volume and inversely proportional to arterial compliance.
What increases pulse pressure?
PP increases during vigorous exercise due to increased stroke volume. It also increases in states of decreased elasticity of the aorta (e.g. atherosclerosis and aging).
What decreases pulse pressure?
During a hypovolemic shock (e.g. severe hemorrhage), there is an increase in peripheral resistance and a decrease in PP.
What happens regarding blood volume when you lie down?
The rise in venous return that occurs when moving to a supine position increases pulmonary blood volume, stroke volume, and arterial BP, resulting in a greater firing rate in the baroreceptors (which respond to stretch).
What effect does anaemia have on cardiac output?
It causes a sustained increase in cardiac output because the heart has to pump more blood each minute to deliver enough oxygen to the tissues of the body
Which is the most important baroreceptor?
Carotid sinus
What happens with baroreceptors when BP increases?
They respond to stretching of the vessel wall. A sudden increase in pressure causes wall stretch and passive expansion, leading to increased firing frequency of action potentials.
What happens with baroreceptors when BP decreases?
They fire less. At lower than 60mmHg they don’t fire
What is the second heart sound and what enhances/ splits it?
Closure of aortic and then pulmonic valve. The splitting enhanced by inspiration because Inspiration results in increased right ventricle preload leading to a slightly longer ejection time and delayed closure of the pulmonic valve
What is the appropriate fluid to give in major sepsis?
Sepsis leads to leaky capillaries and large fluid shifts which need replacing with sodium containing fluids.
What are adult daily sodium and potassium requirements?
1mmol/kg
What happens to total body water with age?
It decreases
What is excreted most when a person is sweating excessively due to exercise?
More water than sodium
What happens to the ECF and ICF when a person is sweating excessively due to exercise?
ECF becomes more hypertonic, due to the concentration gradient difference, ICF fluid will go to ECF by osmosis thus decreasing ICF volume
What happens to ICF and ECF if a person drinks 2L of water just after exercising and sweating excessively?
When that person drinks 2 liters of water, the absorbed water will cause the ECF to become more hypotonic. This will allow water flow from ECF to ICF, thus the ICF volume increases.
