Short Term BP Control- Exam 1 Flashcards
What does control of blood flow to local tissue depend on?
Maintaining a constant pressure drop across the tissue
What two components are involved in maintaing a constant pressure drop across the tissue?
Constant mean arterial pressure
Constant central venous pressure
What are some mechanisms for controlling blood pressure?
Aldosterone Baroreceptors Capillary fluid shift Chemoreceptors CNS ischemic response Renal-blood volume pressure control Renin-angiotensin-vasoconstriction Stress relaxation of vasculature
What type of mechanism is aldosterone?
Hormonal
What type of mechanism is baroreceptors?
Nervous
What type of mechanism is capillary fluid shift?
Physiologic
What type of mechanism are chemoreceptors?
Nervous
What type of mechanism is CNS ischemic response?
Nervous
What type of mechanism is Renal-blood volume pressure control?
Kidneys
What type of mechanism is renin-angiotensin-vasoconstriction?
Hormonal
What type of mechanism is stress relaxation of the vasculature?
Physiologic
Which blood pressure control mechanisms are activated within seconds?
- Baroreceptors
- Chemoreceptors
- CNS ischemic response
- Stress relaxation
Which blood pressure control mechanisms are activated within minutes?
- Capillary
6. Fluid Shift
Which blood pressure control mechanisms are activated within hours?
- Aldosterone
8. Renal-blood volume pressure control
What blood pressure control mechanisms has the greatest ability to create change?
Renal-blood volume pressure control
CNS ischemic response mechanism
Range and Peak
0 to 75 mmHg
Peak: 0 mmHg
Chemoreceptor response mechanism
Range and Peak
20- 110 mmHg
Peak: 60 mmHg
Renin-Angiotensin vasoconstriction
Range and Peak
35- 115 mmHg
Peak: 75 mmHg
Baroreceptor response mechanism
Range and Peak
50- 225 mmHg
Peak: 115 mmHg
Parasympathetic Nervous Control
Regulation of HR
Small affect on contractility
Minimal regulation of circulation
Sympathetic Nervous Control
Regulation of circulation
Regulation of contractility
Vasomotor Center
Parasympathetic impulses via spinal cord & peripheral sympathetic nerves to all arteries, arterioles, veins
Where do sympathetic nerve fibers exit spinal cord?
Via all thoracic spinal nerves & first two lumbar spinal nerves
Where do sympathetic nerve fibers enter the sympathetic chains?
Either side of spinal cord
What are the two routes sympathetic nerve fibers go to circulation?
- Specific sympathetic nerves to vasculature of internal viscera & heart
- Peripheral portions of spinal nerves to peripheral vasculature
What tissue receive sympathetic innervation?
Arteries, arterioles, venules, veins of most tissues receive sympathetic innervation; some metarterioles & precapillary sphincters of mesenteric blood vessels innervated
Are most sympathetic nerve fibers vasconstrictor or vasodilator?
Vasoconstrictor (few vasodilator)
Where is vasoconstriction potent?
Kidneys, intestines, spleen, kidney
Where is vasoconstriction weaker?
Skeletal muscle and brain
When sympathetic impulses are sent to blood vessels, impulses also go where?
Adrenal medulla resulting in secretion of epinephrine and norepinephrine
What is able to change resistance/change flow through each tissue?
Small arteries/arterioles
What is able to change volume held in vessels thus changing venous return?
Veins
Where is the vasomotor center located?
Bilateral
Reticular substance: medulla, lower third of pons
Parasympathetic impulses are via what nerve?
Vagus nerve
Sympathetic impulses are via what structures?
Spinal cord & peripheral sympathetic nerves to all arteries, arterioles, veins
What does the vasomotor center do?
Regulates amount of vascular constriction and cardiac activity (i.e. heart rate and contractility)
3 components of the vasomotor center
Vasoconstrictor area
Vasodilator area
Sensory area
Where is the vasoconstrictor area?
Bilateral; anterolateral part of upper medulla
What does the vasoconstrictor area of the vasomotor center do?
Sends fibers to all areas of spinal cord; fibers excite vasoconstrictor neurons of sympathetic system