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35 Cards in this Set

  • Front
  • Back
Functions
Substrates and oxygen carried to call cells
Metabolites and CO2 carried from all cells
Flow to skin and extremities is regulated (thermoregulation)
Hormone distribution
Body defense mechanisms are carried by CVS
Fluid movement is essential for living cells to exchange materials with their environment
Total body water=
extracellular fluid ( plasma +interstitial fluid) + intracellular fluid
The extracellular fluid compartments are:
Blood plasma
Interstitial fluid, which is the ECF outside the capillaries and the site of metabolic exchange
The extracellular fluid compartments require two interconnected system:
Cardiovascular system for
Lump-vascular system for
blood plasma

interstitial fluid
The interstitial fluid (site of metabolic exchange) is released from the
arterial ends of the capillaries as an ultafiltrate of blood
Bulk transport
Substances carried between organs
TRANSPORT RATE =
FLOW RATE X CONCENTRATION
The velocity of blood at any level =l
total flow divided by cross sectional area at that leve
Therefore blood flow is slowest at the
capillaries, favoring gas and nutrient exchange.
Most substances cross capillary walls by ...
Called ...
PASSIVE DIFFUSION
TRANSCAPILLIARY SOLUTE DIFFSION
Four factors determine diffusion rate
Concentration difference
Surface area for exchange
Diffusion distance
Permeability of wall to diffusing substance
Diffusion distance
Diffusion is very slow over distances of
1 cm but very rapid over distances of 4-7 micrometers
Basic design for tubes delivering fluid metabolites to interstitial fluid is:
Very thin walled tube
As close as possible to every cell in body
Tissue barrier at level of the capillary is a single squamous epithelial cell called an
ENDOTHILIAL CELL
Pump- the heart
Contracts and propels blood out to the body
Arterial system
Conveys blood from heart to the capillaries
Venous system
Conducts blood from capillaries back to heart
Lymph-vascular system
Carries lymph from the interstitial fluid spaces of the body back into the blood vascular system
... is the driving force for the flow
PRESSURE DIFFERENCE
VASCULAR RESISTANCE is
a measure of how difficult it is to make blood flow through a tube
I.e. the pressure required to make a given volume over a certain distance
Therefore there are only two ways that blood flow through any organ can be changed
Changing pressure difference across the vascular bed
Changing vascular resistanc
Therefore blood flow depends on:
PRESSURE DIFFERENCE

TOTAL PERIPHERAL RESISTANCE

VISCOSITY
Mean arterial pressure minus central venus pressure

Small changes in radius have powerful effects on flow
When radius or diameter of a blood vessel doubles, the flow increases by 16

This is not a variable that is easily changed but it may influence vascular resistance
The greatest drop will occur in a area of greatest resistance
This occurs in
ARTERIOLES
blood flow to a particular organ can be altered by adjusting the resistance of the arterioles without greatly affecting
pressures and flows in other organs
Four forces influence fluid movement across capillary walls
Capillary blood pressure (Pc)
Plasma colloic osmotic pressure (oncotic pressure πp)
Interstitial fluid hydrostatic pressure (Pif)
Interstitial fluid colloid pressure πif)
net exchange pressure =
(Capillary blood pressure + Interstitial fluid colloid pressure) - (Plasma colloic osmotic pressure +Interstitial fluid hydrostatic pressure )
THERE IS A SLIGHT PREDOMINANCE OF
FILTRATION OVER REABSOTPTION
Left side of the heart pumps
oxygenated blood to the Systemic circulation- high pressure/ high resistance
Right side of the heart pumps
deoxygenated blood to the Pulmonary system- low pressure/low resistance
FROM THE HEART TO THE BLOOD VESSELS, this is called
SYSTOLE
When the ventricle relaxes, pressure within the ventricle falls below that in the atrium, and AV valve opens and the ventricle fills with blood. THIS IS CALLED
DISATOLE.
Three features of the hear t are very important features for effective functioning
Conductivity
Contractility
Autorhythmicity
Requirements for effective cardiac pumping
Contraction of individual cardiac muscles must be regular and synchronized
Valves must be open fully
Valves must not leak
Ventricles must fill adequately during diastole