Nervous System Regulation Flashcards
Local control of blood flow to tissue by which 2 theories?
Vasodilator and O2 Lack theories
Characteristic of elastic arteries
Stretch and recoil every heartbeat to maintain pressure
Characteristic of muscular arteries
Adjust diameter for blood pressure control, can regulate flow to parts of body
Characteristic of arterioles
Control blood flow to tissue
Characteristic of capillaries
serve tissues and are for local control of blood to tissue
Venules? What do they do?
collect blood from capillaries
Characteristic of veins?
Reservoir, transport to heart
Autonomic Nervous System regulates locally or globally?
Has which 3 effects on the CVP system?
Globally
1) redistributes blood flow to different areas of body
2) affects HR
3) rapidly changes arterial blood pressure
Which system has most influence in circulation regulation?
Which system assists in heart function regulation?
SNS is primary influence in circulation
PSNS assists in regulation of heart function
Where do the SNS vasomotor nerves leave the body at?
T1-L2
SNS innervates all vessels except which 3?
Capillaries, precapillary sphincters, metarterioles
What happens to vessels of SNS innervation?
SNS –> vasoconstriction –> High BP
SNS stimulation decreases vessel volume by what?
Vasoconstriction
Define circulatory shock
Condition where blood vessels are not properly filled and blood cannot circulate normally
What is hypovolemic shock?
Severe loss of blood/fluids that make the heart unable to pump blood to rest of the body
What is vascular shock?
characterized by a normal blood volume, but extreme vasodilation, often related to a loss of vasomotor tone, resulting in poor circulation and a rapid drop in blood pressure
TOO MUCH VASODILATION
What is cardiogenic shock?
heart suddenly can’t pump enough blood to meet your body’s needs. The condition is most often caused by a severe heart attack.
What is the SNS affect on HR?
Increases heart rate to circulate fuel and oxygen to vital organs for activity and defense
SNS affect on BP?
Increases blood pressure to get blood to the brain and vital organs
SNS affect on blood loss?
Increases blood clotting ,which minimizes blood loss if wounded during defense such as fight/flight
due to vasoconstriction
Vasoconstriction fibers distributed to all segments of circulation but largest to which 4 areas of the body and why?
Kidneys, intestines, spleen, and skin.
Want to vasoconstrict blood flow to areas not needed for flight or fight arousal period. Want to maximize effiency to other areas
Where are SNS fibers for vasoconstriction less distributed to?
skeletal mm and brain
Where is the vasomotor center located?
Medulla Oblongata
3 areas of the vasomotor center include:
vasoconstrictor area, vasodilator area, sensory area
What happens if normal vasoconstrictor tone is lost?
vasodilation, widening of vessels will occur.
BP is not maintained and may drop
SNS secretes what substance?
Norepinephrine
Vasodilator area does what to the vasoconstrictor area?
Inhibits it.
Which area helps control both vasoconstriction and vasodilation areas?
Sensory Areas
Where are the sensory areas received?
Circulatory system via vagus and glossopharyngeal nerves
Adrenal medulla is stimulated by blood vessels and then secrets what 2 substances?
Norepinephrine and epinephrine into blood system
Epinephrine has what affect on some tissues?
vasodilation
Cardiac center is located where and has what function?
Adjacent to vasomotor center. Adjusts HR and force of contraction to meet needs via the cardioaccelerator center and cardioinhibitory center
What 2 centers does the cardiovascular center make up?
Cardiac center + vasomotor center
Stimulation of vasomotor center has what affect on the cardiac center?
Stimulates cardiac centers
Therefore Heart Function and Vascular Function controlled SIMULTANEOUSLY!
- Increases in vasoconstriction with increase HR
- Decreases in HR with decreases in vasodilation
What response is considered most sensitive of nervous system responses?
Blood pressure
Can increase x2 within 5-10 seconds
Increase in Arterial Pressure result of simultaneous stimulation of what 2 things?
vasoconstriction and cardioacceleration
Increases in Arterial Pressure have what 3 major changes?
Arterioles constrict, veins and other large vessels constrict, and SNS stimulation of heart occurs
How does the body maintain normal arterial pressure?
Baroreceptors are in nearly every large artery of the neck and thorax are PRESSURE sensitive.
barometer measures decline in MAP? What happens next?
Initiation of reflex vasoconstriction and increases cardiac output –> bp rise
Standing up from a chair creates orthostatic hypotension, how does the body react when with the baroreceptors?
low BP fall will increase vasoconstriction and increase cardiac output so BP will rise for homeostasis.
Functions of the baroreceptor function include 3 things:
Protects against acute changes in BP as a buffer system
Minimizes variation in BP
But is ineffective during prolonged pressure changes due to adaptability.
Example of adaptability of a baroreceptor in hypertension?
Reset at higher set point due to prolonged period of HTN, limiting longterm response to higher perceived pressure
Chemoreceptor is in contact with which blood ?
What does it sense?
What does it initiate?
Arterial blood
Senses low O2 or high CO2 or H+ that results with drops in arterial pressure.
Reflexive vaso/venoconstriction response
What does the chemoreceptor increase?
cardiac output, heart rate, vasoconstriction
Bainbridge reflex of the atria does what?
What kind of receptor is it?
Receptor= stretch
increases in arterial pressure increase in HR and strength of contraction to prevent blood from backing up.
Low pressure receptor in the atria will do what?
Sense and minimize arterial pressure changes. If need be, it will initiate more fluid retention to increase pressure.
Damage to atria can result in?
Damaged and less effective pressure receptors in atria.
If CNS ischemia happens, what occurs?
STRONG REACTION OF VASOCONSTRICTOR AND CARDIOACCELERATOR CENTERS
LARGE RISE IN ARTERIAL PRESSURE
What are the steps of cerebral ischemic response?
1) large drop in BP
2) drop in cerebral blood flow
3) increases in CO2 and H+
4) ACTIVATION OF VMC
5) increase sympathetic activity
6) increase in TPR, HR
7) restoration of BP
As the SNS activates what happens to EDV and ESV levels?
ESV levels decrease and EDV increases
Formula for cardiac output?
Stroke volume x heart rate
