L 21 Intro to the CVS Flashcards
list the major functions of the CVS
- deliver O2 and nutrients rapidly to all cells of the body
- remove CO2 and waste products
- control system: distributes hormones to tissues
- regulates body temp
describe the organization of the CVS
RA - RV - pulm a. - lung - pulm v. - LA - LV - aorta - circulation - superior/inferior VC
why must the output from the L heart must be the same as the output from the R heart?
all homeostatic mechanisms work to maintain equal CO on both L and R side heart.
if there is an imbalance - there are big problems!
define systole
contraction of heart
define diastole
relaxation of heart
what features distinguish pulmonary and systemic circulations
The RV contracts and pumps deoxygenated blood through the pulmonary artery, which divides and supplies the lungs. Inhaled O2 diffuses into the blood and CO2 diffuses out and is exhaled. The oxygenated blood returns to the LA through the pulmonary veins, thus completing the short pulmonary circulation.
The LV pumps out an equal volume of oxygenated blood to all tissues of the body (except the lungs). The blood flows through the aorta, which gives off several major arteries. Repeated branching gives rise to millions of capillaries where the ultimate function of the CVS is fulfilled – the delivery of O2 and nutrients to the tissues and the removal of waste products. The deoxygenated blood returns to the RA via a convergent system of veins that drain into the superior and inferior vena cavae, which join and enter the RA, thus completing the systemic circulation.
define portal circulation
Some organs (liver, kidney brain) are connected in series with another organ such that they receive the venous outflow of another organ.
what is the significance of portal circulation
Liver: Has a direct arterial supply via the hepatic artery, but ~70% of its blood supply comes from the hepatic portal vein, which is venous blood drained from the gut and spleen. The advantage is that digestive products can be transported directly from the gut to the liver, for further processing.
Kidney: Afferent arterioles supply the glomeruli and efferent arterioles carry venous blood from the glomeruli. These efferent arterioles then supply oxygen and nutrients to the kidney tubules.
Brain: A portal system exists between the hypothalamus and the pituitary gland which functions to transport hypothalamic hormones to the pituitary.
define cardiac output
the volume of blood ejected from one ventricle per minute
define stroke volume
Volume of blood ejected (from either ventricle) per heart beat
how is SV calculated
CO = Sv x HR
SV = CO / HR
what are the normal values for CO, SV, HR
CO = pulm. blood flow = 5 L/min at rest SV = normal = 70-80 ml, athlete = 100-125 ml HR = normal = 72 bpm, athlete = 35 bpm
what is the basic law of flow?
flow = ΔP / R
Bulk Flow Law (Darcy’s Law)
ΔP - pressure gradient
R - resistance
explain why velocity of flow is slowest in capillaries
Velocity = Flow (Cardiac Output) / Area
increase area, decrease velocity
capillaries have the largest cross sectional area and the slowest velocity of blood flow!
why does blood flow unidirectionally?
presence of one way valves!
