Fewell - Neurohumoral control of the heart and circulation Flashcards
Organ Blood Flow (Supply)
is Closely Coupled to
__________________
Organ Metabolic Activity (Demand)
ORGAN BLOOD FLOW
is determined by _ and _
DRIVING PRESSURE
and
ORGAN VASCULAR
RESISTANCE
What the CONTROLLED
VARIABLE for ORGAN BLOOD FLOW?
systemic arterial pressure
because it is the driving pressure that allows each one of the tissues to determine their own blood flow by altering vascular resistance
Blood volume of normal adult
5L
Distribution of blood volume in the circulatory system
>heart
7%
Distribution of blood volume in the circulatory system
>arteries
13%
Distribution of blood volume in the circulatory system
>arterioles and capillaries
7%
Distribution of blood volume in the circulatory system
>veins
64%
Distribution of blood volume in the circulatory system
>pulmonary vessels
9%
where is the majority of blood volume mantained?
in the veins
large arteries are called __ vessels
distrubing vessels
aterioles are called __ vessels
resistance vessels
capillaires are called __ vessels
exchange vessels
venules/veins are called __ vessels
capacitance vessels
organ flow equation is
organ flow = driving pressure / resistance
venule vs arterial side reclining vs upright
reclining has even distrubtion within venules and an even distrubtion within aterial side
>HOWEVER when upright the venule side has a higher concentration/buildup near the legs and feet (because veins are highly compliance and high volume)
blood flow equation is
blood flow = driving pressure/vascular resistance
>consider that 120/80 is sufficent in humans to supply blood to organs above the heart (below this may not be able to supply blood to neck, brain …etc BUT above may brust blood vessels)
>BUT in giraffes blood pressure must be 300/180 because some organs are higher up from the heart (probably have more collagen in their walls of arteries to make up for high blood pressure)
pulmonary circulation requires adequate driving pressure in the same was that __ does
systemic circulation does
>because the pulmonary circulation also has organs above the heart that need to be reached with the 25/8 blood pressure
>BUT don’t want it too high or too low
why is pulmonary circulation have a lower BP than the systemic circulation
the systemic circulation has to reach organs higher up than the pulmonary circulation (ex: brain vs lungs)
The heart normally accepts blood at _____ during diastole and
propels it forward at ____
during systole
low filling pressure, higher pressures
An adequate blood volume is required for ___
and _
venous return and low-pressure filling of the heart
can humans handle a decrease in blood volume and if so how?
Yes using homeostasis! But only a modest (10%) decrease
>e.g. via sympathetic vasoconstriction
What do we use to regulate blood volume?
-via low pressure receptors
where are low pressure receptors found
- cardiopulmonary (pulmonary vessels)
- atrial (walls)
- large systemic veins
what are the effectors of low pressure receptors
hormones and kidneys
what do low pressure receptors releases when pressure is low?
-ADH
what do low pressure receptors releases when pressure is high?
-ANP
Decreased atrial receptor firing causes
hypothalamus -> posterior pitutiary -> vasopressin ->
-v1 -> constriction (increased systemic vascular resistance)
-v2 -> kidney fluid reabsorption (increased blood volume)
_________________________-
leads to increased arterial pressure
Arterial receptors function
fine tune/set driving pressure needed to prefuse driving pressure to get nurtients/02 to organs via tissues
aterial baroreceptors function
sense pressure (driving pressure) and inform CV center
