Guyton Kap.18- Nervous Regulation Of Circulation

Front 1

Vessels innnervated by sympathetic nervous system:

Back 1

All vessels except capillaries

Front 2

Distribution of vasoconstrictor nerve fibers:

Back 2

More in kidneys, intestines, spleen and skin but less in skeletal muscle and brain.

Front 3

Vasomotor center:

Back 3

Bilaterally in the reticular substance of the medulla and of the lower third of the pons.

Front 4

Parasympathetic impulses is transmitted to cardiovascular system through:

Back 4

Vagus nerve

Front 5

Sympathetic impulses is transmitted to cardiovascular system through:

Back 5

Spinal cord and peripheral sympathetic nerve fibers

Front 6

Vasoconstrictor area:

Back 6

Bilaterally in the anterolateral portions of the medulla.

Front 7

Vasodilator area:

Back 7

Bilaterally in the anterolateral portions of lower half of medulla. They inhibit vasoconstrictor acticity

Front 8

Vasomotor tone:

Back 8

One half to two impulses fired per second by vasoconstrictor center maintain normal vasoconstrictor tone.

Front 9

Lateral portions of vasomotor center:

Back 9

Transmits excitatory impulses to the heart which increases heart rate and contractility.

Front 10

Medial portions of vasomotor center:

Back 10

Sends signals to adjacent dorsal motor nuclei of vagus nerves which sends parasympathetic signals to the heart to decrease heart rate and slightly decrease contractility.

Front 11

Hypothalamus and its relation to vasomotor center:

Back 11

Posterolateral portions cause excitation while the anterior portion cause mild excitation of inhibition.

Front 12

Norepinephrine:

Back 12

Secreted at the endings of the vasoconstrictor nerves and act on alpha adrenergic receptors of smooth mm.

Front 13

Activation of adrenal medulla:

Back 13

Sympathetic innervation in the same way as for vessels. Cause adrenal medulla to secrete epi and norepi into the blood stream.

Front 14

Emotional fainting- Vasovagal syncope:

Back 14

Disturbing thoughts in cerebral cortex from emotional disturbances--> vasodilatory center of anterior hypothalamus next to vagal centers of medulla---> vagus nerve to heart (slowing of HR) and through spinal nerves to the sympathetic vasodilator nerves of muscles (vasodilatation)

Front 15

Most important function of nervous system in regulation of circulation:

Back 15

Ability to cause rapid increase in arterial pressure by stimulation of vasoconstrictor and cardioaccelerator functions of sympathetic nervous system + blockage of parasympathetic NS

Front 16

Rapid increase of arterial pressure by the nervous system:

Back 16

1. Constriction of arterioles (increases total peripheral resistance)
2. Constriction of veins and large vessels (Redistribution of blood from periphery to the heart --> increased preload--> increased force of contraction)
3. Direct effect on heart (increased HR and contractile force)

Front 17

Norepinephrine:

Back 17

Secreted at the endings of the vasoconstrictor nerves and act on alpha adrenergic receptors of smooth mm.

Front 18

Activation of adrenal medulla:

Back 18

Sympathetic innervation in the same way as for vessels. Cause adrenal medulla to secrete epi and norepi into the blood stream.

Front 19

Emotional fainting- Vasovagal syncope:

Back 19

Disturbing thoughts in cerebral cortex from emotional disturbances--> vasodilatory center of anterior hypothalamus next to vagal centers of medulla---> vagus nerve to heart (slowing of HR) and through spinal nerves to the sympathetic vasodilator nerves of muscles (vasodilatation)

Front 20

Most important function of nervous system in regulation of circulation:

Back 20

Ability to cause rapid increase in arterial pressure by stimulation of vasoconstrictor and cardioaccelerator functions of sympathetic nervous system + blockage of parasympathetic NS

Front 21

Rapid increase of arterial pressure by the nervous system:

Back 21

1. Constriction of arterioles (increases total peripheral resistance)
2. Constriction of veins and large vessels (Redistribution of blood from periphery to the heart --> increased preload--> increased force of contraction)
3. Direct effect on heart (increased HR and contractile force)

Front 22

Norepinephrine:

Back 22

Secreted at the endings of the vasoconstrictor nerves and act on alpha adrenergic receptors of smooth mm.

Front 23

Activation of adrenal medulla:

Back 23

Sympathetic innervation in the same way as for vessels. Cause adrenal medulla to secrete epi and norepi into the blood stream.

Front 24

Emotional fainting- Vasovagal syncope:

Back 24

Disturbing thoughts in cerebral cortex from emotional disturbances--> vasodilatory center of anterior hypothalamus next to vagal centers of medulla---> vagus nerve to heart (slowing of HR) and through spinal nerves to the sympathetic vasodilator nerves of muscles (vasodilatation)

Front 25

Most important function of nervous system in regulation of circulation:

Back 25

Ability to cause rapid increase in arterial pressure by stimulation of vasoconstrictor and cardioaccelerator functions of sympathetic nervous system + blockage of parasympathetic NS

Front 26

Rapid increase of arterial pressure by the nervous system:

Back 26

1. Constriction of arterioles (increases total peripheral resistance)
2. Constriction of veins and large vessels (Redistribution of blood from periphery to the heart --> increased preload--> increased force of contraction)
3. Direct effect on heart (increased HR and contractile force)

Front 27

General function of baroreceptor reflex.

Back 27

To adjust BP rapidly according dayly movements and provide effectively moment to moment regulation of BP, and avoid great variations in BP.

Front 28

Are the baroreceptors involved in long term regulation of BP:

Back 28

Most likely not, because they reset according to the mean pressure after a day or two. Increasing long term pressure from 100 to 160 mmHg leads to increased firing the first day, then it resets to that pressure and stops firing.

Front 29

Chemoreceptors and its control of arterial BP:

Back 29

Carotid bodies and aortic bodies with nutritive arteries supplying arterial blood for examination. Detect low O2, high CO2 and low pH and excite vasomotor center ---> increased arterial BP. Most important in BP below 80 mmHg

Front 30

Receptors in atria and pulmonary arteries and its regulation of BP:

Back 30

Sensitive to low pressure increase of volume after infusions. Activate reflex system and makes it more potent.

Front 31

The Bainbridge reflex:

Back 31

Stretch receptors of the atria elicit the Bainbridge reflex that transmits its afferent signal through the vagus n. to the medulla---> efferent through vagus and sympathetic nn. ==> increase HR and contractility (Prevents accumulation of blood in veins, atria and pulmonary circulation)

Front 32

CNS ischemic response:
(Most powerful of all activators of vasoconstrictor system)

Back 32

Vasomotor center responds directly to ischemia (by the failure to bring the accumulating CO2 away from the vasomotor center during low BP)---> Arterial pressure rises as high as heart can pump. Can increase BP 250 mmHg for as long as 10 min.

Front 33

Cushing reaction:

Back 33

Increased pressure of CSF that cuts of circulation activates the "CNS ischemic response" which increase BP higher than CSF pressure to ensure perfusion.