Study your flashcards anywhere!

Download the official Cram app for free >

  • Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off

How to study your flashcards.

Right/Left arrow keys: Navigate between flashcards.right arrow keyleft arrow key

Up/Down arrow keys: Flip the card between the front and back.down keyup key

H key: Show hint (3rd side).h key

A key: Read text to speech.a key


Play button


Play button




Click to flip

67 Cards in this Set

  • Front
  • Back
3 Major functions accomplished by nervous regulation of circulaton:
1. Global functions like redestribution of blood to the body
2. Alteration of the heart's pumping activity
3. Rapid control of systemic arterial pressure
Most important component of ANS regulating circulation:
Main function of Parasympathetics in circulation:
Regulating heart function
What do Sympathetic nerves innervate?
-Internal viscera
What Blood vessels are innervated by sympathetic nerves?
All but microarterioles, capillaries, or precapillary sphincters.
What effect do sympathetic nerves have on small arteries and arterioles?
Increase Resistance
Decrease rate of bloodflow
What effect do sympathetic nerves have on Large veins?
Decreased Volume to push blood into the heart (increase venous return).
What is the function of the Parasympathetics?
Control of the heartrate via the Vagus Nerve.
How specifically does Sympathetic innervation affect the heart?
Via Norepinephrine on Muscarinic receptors, it has 2 effects:
1. Increased contractility
2. Increased heartrate
What are the principle nerve fibers carried by the Sympathetic nerves to vessels?
-Vasoconstrictor fibers
(Few Vasodilator fibers)
Where i the sympathetic vasoconstrictor effect most powerful?
Where is the sympathetic vasoconstrictor effect least powerful?
What controls the Vasoconstrictor system?
The vasomotor center in the brain
Wher in the brain is the Vasomotor Center?
Bilaterally - in the lower 1/3 of the pons, and reticular substance of medulla.
What types of signals are transmitted from the Vasomotor center in the brain?
-Parasymp outflow via Vagus to the heart
-Symp outflow via spinal cord and peripheral nerves to all vessels except tiny ones.
For sympathetic heart innervatn:
Rec = Beta1
Effect = Incr HR + Incr contractility
3 Distinct Areas identified in the Vasomotor Center:
1. Vasoconstrictor (C1)
2. Vasodilator (A1)
3. Sensory area (A2)
Where is the Vasoconstrictor area? What is its output?
Anterolateral Upper Medulla - gives Sympathetic output
Where is the Vasodilator area?
What is its output?
Anterolateral Lower Medulla
Inhibits Vasoconstrictor
Where is the Sensory area?
In the NTS - Nucleus tractus solitarii
What is the NTS function?
Recieves sensory signals from Vagus and Glossopharyngeal nerves from baroreceptors and Controls areas C1 and A1
What is the function of the Cardiac center?
Control of heart rate and contractility
3 Important areas of the brain important in nervous reg of circulation:
1. Reticular substance
2. Hypothalamus
3. Motor cortex
What is the normal state of blood vessels?
Partially contracted - via Vasomotor Tone
What is responsible for Vasomotor Tone?
Continual firing of Sympathetic Vasoconstrictor Tone from the Vasoconstrictor Center.
What happens if you give an animal total spinal anesthesia?
Their blood pressure drops dramatically due to loss of vasomotor tone.
What happens if you inject Norepinephrine in that animal a few minutes later?
This being the principle NT responsible for vasomotor tone, arterial pressure rose for 1-3 minutes until all NE diffused.
What portion of the Vasomotor center sends symp impulses to the HEART?
Lateral portions
What portion of the Vasomotor center sends signals to the heart for decreased heart pumping?
MEDIAL portions - signal adjacent dorsal motor nuclei of the VAGUS nerves.
On what receptors does NE act to cause vasoconstriction?
What are the 2 principle controllers of Mean Arterial Pressure?
-Total peripheral resistance
-Cardiac output
How can you change MAP? 3 ways:
1. Increase TPR by constricting arterioles
2. Constricting Veins to increase venous return
3. Change CO by increasing HR and contractility
What is the most important thing to remember about nervous control of BP?
IT is by far the most rapidly responding controller of BP - both positive and negatively.
What is the most important feedback mechanism for controlling BP w/ the ANS?
2 Sites of Baroreceptors:
1. Carotid sinus
2. Aortic arch
What nerves transmit fibers from
-The carotid sinus
-The aortic arch
Carotids: Hering's nerve
Aorta: Vagus nerves
Where are the signals from the carotids transmitted to?
-Glossopharyngeal nerves via Hering's nerves -> NTI
Where are the signals in the aortic arch transmitted to?
-Vagus nerves to NTI
To what pressure range do Carotid baroreceptors respond? How are aortics different?
Carotids: 60 mm Hg - 180 mm Hg
Aortics: respond to CHANGES in pressure
Where is the sensitivity of baroceptors highest?
Right around where it needs to be; from 60-180
What determines the intensity with which a baroceptor is stimulated?
The nature of the stimulus:
-if pressure is CHANGING it will stimulate with twice as much intensity.
What happens when carotid baroceptors detect an increase in BP?
It increases the rate of firing which results in:
1. Inhibiting of the vasoconstrictor center
2. Activation of the parasymp vagal center
What are the net effects in the from a baroceptor stimulus?
1. Vasodilation
2. Decreased HR and contractility
What will happen if you take out (occlude) the carotid arteries?
The vasomotor center will become very active and try to increase aortic arterial pressure b/c it lacks their signal.
What happens when you remove the occlusion?
Blood pressure returns to normal b/c it rises again in the carotids.
In what "code language" do the baroreceptors speak?
Intensity of stimulus = frequency of firing - the more CHANGE in BP, the stronger stim.
What kind of a curve is generated for that 'code'?
Change in impulse frequency
Change in Blood Pressure
(Plot I vs. P)
On the Baroreceptor impulse vs. BP plot what does the plateau mean?
All baroreceptors are stimulated and firing; no more intensity can be achieved.
What is the relationship between the carotid distending pressure, muscle sympathetic nerve activity, and cardiac RR interval?
As pressure increases, sympathetic nerve activity decreases, and RR interval goes up because it's 1/HR and HR goes down.
Why does HR go down when BP goes up?
Because the signal is sent to the vasomotor center inhibiting sympathetics and exciting parasympathetics (vagal).
How does baroreceptor regulation act in long-term changes in BP?
The receptors reset themselves so that they can still do their job even if baseline BP is now 130 instead of 100 for example.
What do Chemoreceptors sense?
Where are chemoreceptors located?
About the same place as baroreceptors.
How is chemoreceptor stimulation related to blood pressure?
When MAP falls O2 will lack and CO2 and H+ will be in excess.
What is the vasomotor center response to chemoceptors?
Stimulates Sympathetic output
Stimulates Vagal output too!
So what is the net effect of Vasomotor stimulation by chemoreceptors?
An increase in MAP
What BP detectors are in the Atria and Pulmonary artery?
LOW-bp detectors - "low" because the atria and pulm circ are low pressure areas.
What triggers the low BP detectors in the Atria/Pulm A?
Increased circulation through the pulmonary system
What is the response to low-pressure receptor stimulus?
-Decrease secretion of ADH
-Increased GFR
-Decreased Na reabsorption
To get the BP to go down
How does stimulus of the Atria stretch receptors effect the kidneys?
It increases dilation of the afferent glomerular arterioles
What happens in the brain when cerebral blood flow is reduced? (ischemia)
Buildup of CO2 which stimulates the vasomotor center to increase arterial pressure.
What is the nature of this stimulus?
One of the STRONGEST stimulus that will ever reach the vasomotor center - but RARE
When is the CNS ischemic response employed?
Only in emergency
What is the mechanism of the CNS ischemic response?
1. CNS ischemia
2. Increased CO2
3. Stimulates vasomotor center
4. Respond w/ increased MAP
What is the threshold low for activation of the CNS ischemia response?
60 mm Hg
-Best is at 15-20
What is the Cushing reaction?
A response to high CSF pressure that is cutting of cerebral bloodflow - Cushing response is to increase MAP until it exceeds the CSF pressure and allows bloodflow.
How does prolonged ischemia effect the vasomotor center?
Depresses it