Circulatory System and Hemodynamics Flashcards
What is the circulatory system composed of?
heart, blood vessels, blood for transportation
What are the 2 loops of the circulatory system?
- shorter pulmonary circuit: exchanges blood between heart and lungs
- longer systemic circuit: distributes blood throughout other systems/tissues
Where do both systems begin and end?
in the heart
What are the functions of the circulatory system?
- transport essential substances to tissues
- remove metabolic waste products
- homeostasis (temp. regulation, fluid maintenance, meeting metabolic demands)`
What is an important characteristic of the circulatory system?
heart pumps about 1800 gallons of blood throughout the day
What is the order of blood flow within the heart?
IVS + SVC -> right atrium -> right ventricle -> pulmonary artery -> pulmonary vein -> left atrium -> left ventricle -> aorta`
What is systole?
when the heart contract to pump blood out
What is diastole?
when the heart relaxes after contraction
What is the trend of CO2 and O2 in pulmonary arteries?
increase in CO2, decrease in O2
What is the trend of CO2 and O2 in pulmonary veins?
decrease in CO2, increase in O2
How do valves work?
- open tricuspid and mitral valves
- close tricuspid and mitral valves
- open pulmonic and aortic valve
- close pulmonic and aortic valve
What are the 3 things important for regulation?
endothelium, elastic tissue, smooth muscle
What is the blood composed of?
- 55% plasma
- buffy coat: platelets and white blood cells
- formed elements
What is the function of albumins?
maintain hydrostatic pressure
What is the role of globulins?
deals with immune system
What is the role of fibrinogen?
deals with blood coagulation
What is the respiratory function of blood ?
- transport O2 from lungs to tissues
- transport from CO2 from tissues to lungs
What is the nutrition function of blood ?
transport food from gut to tissues
What is the excretory function of blood ?
transport waste from tissues to kidney and skin
What is the regulatory function of blood ?
- water content of tissues
- water exchanged through vessel walls to tissue
How does blood regulate body temp. ?
antibodies, antitoxins, white blood cells
What are the functions of blood?
- respiratory
- nutrition
- excretory
- regulatory
- body temp.
- acid-base balance
- coagulation
Hematocrit includes what type of cells?
red blood cells
What is hematocrit?
proportion by volume of blood that consist of red blood cells
What is the hematocrit composition in normal blood?
female: 37-47%
male: 42-52%
What is the hematocrit composition in anemic blood?
depressed hematocrit %
What is the hematocrit composition in polycythemia blood?
elevated hematocrit %
What is the blood reserve?
allows control of blood volume and makes up for fact that capillaries are NOT always open
What are the % of blood volume during blood distribution?
left ventricle: 4%
arteries: 16%
capillaries: 4%
veins: 64%
right heart: 4%
What happens to blood pressure from the aorta to the vena cava?
blood pressure decreases
What drives blood flow?
pressure
What is pulse pressure?
difference between systolic and diastolic pressure
What is volume flow (Q)?
flow volume per unit time (mL/sec) = change in Q/change in T
What is flow velocity (V)?
linear flow; distance per unit time (cm/sec) = change in D/ change in T
What is the trend between velocity and cross sectional area?
V increases as A decreases; inversely proportional
How is resistance determined?
by tube radius, length, and fluid viscosity
What is the effect of tube length on resistance?
resistance varies positively with tube length
What is the main determinant of resistance?
tube radius
Blood flow is controlled by what?
regulating vessel radius
What vessel type has the highest resistance?
capillaries
What is the physiological significance of arterioles?
- biggest drop in BP
- main regulator of blood flow
What is the formula for total resistance?
Rtotal = R1 + R2 + R3
What is the comparison of pressure upstream vs downstream?
pressure downstream is LOWER than pressure upstream
What is the trend with pressure and flow in arteries?
increase in pressure, increase in flow
What is the trend with pressure and flow in arterioles?
decrease in pressure, decrease in flow
What are the 2 principles of resistance in parallel?
- Rtotal of a network of parallel vessels is LESS than the resistance of the vessel having the LOWEST resistance; parallel vessels REDUCE resistance to blood flow
- changing the resistance of a small number of the vessels will have a small effect on Rtotal
What is the physiological significance of parallel circuits?
larger the number of parallel-coupled circuits, the smaller the total resistance
What effect do capillaries have on resistance and pressure?
decrease resistance, decrease change in pressure
What is important to maintain the flow across capillaries?
parallel circuits
What is the purpose of rheology?
deals with deformation and flow of water
What are the 2 types of flow of rheological properties?
laminar and turbulent
What are the characteristics of laminar flow?
linear, ideal, energy efficient
What is the characteristic of turbulent flow?
harmful to vessel wall
Blood viscosity changes depending on what?
tubing dimensions and hematocrit
What is the relationship between flow and fluid viscosity?
they vary inversely (decrease tube diameter = decrease viscosity = decrease resistance = increase Q)
What is the fluid located near the capillary wall?
plasma (slow velocity)
Why do red blood cells traverse capillaries faster than plasma?
it’s aligned with center axis (high velocity)
How can blood flow faster in the center of the vessel?
by decreasing hematocrit
When does shear occur?
when adjacent layers of blood travel at different velocities
When is shear the HIGHEST?
at the blood vessel wall
