Blood pressure Flashcards
(95 cards)
The systolic blood pressure reflects _
The systolic blood pressure reflects maxmimum pressure generated by the left ventricle during systole
* The aortic valve is open at this point and the intraventricular pressure equals the aortic pressure
* Normal ~120
Increasing SVR increases blood pressure; explain
Increasing systemic vascular resistance makes it more difficult for blood to flow from larger arteries –> smaller ones
* Vasoconstriction increases SVR
Name some factors that influence the SVR
- Autonomic nervous system input
- Vessel stretch (myogenic reflex)
- Local factors (nitric oxide, oxygen, co2)
- Circulating signaling molecules (vasopressin, endothelin)
How does the body respond to hypovolemic shock?
In response to hypovolemic shock, the body:
* Induces vasoconstriction
* Increases contractility
* Increases heart rate
In an attempt to compensate for the volume loss
* The desired blood pressure should be high enough to maintain organ perfusion, but not so high as to decrease cardiac output
In cardiogenic shock, the CO drops due to _ and _ cannot compensate adequately, leading to severe hypotension and organ failure
In cardiogenic shock, the CO drops due to myocardial injury and peripheral vasoconstriction and tachycardia cannot compensate adequately, leading to severe hypotension and organ failure
Three systems work together to regulate BP: _ , _ , and _
Three systems work together to regulate BP: cardiovascular , renal , and neural
Mean arterial pressure (MAP) equation
Mean arterial pressure (MAP) is the average arterial blood pressure for one cardiac cycle
MAP = SVR * CO
MAP represents _
Mean arterial pressure (MAP) represents the average arterial blood pressure for one cardiac cycle
* A MAP of less than 60 is usually fatal because tissues cannot stay perfused
Normal MAP is between _ and _
Normal MAP is between 85-95 mmHg
* The heart spends about 2/3 of its time in diastole (80)
* About 1/3 is spent in systole (120)
We have special baroreceptors in the _ and _ that can sense changes in arterial stretch and send signals to the _
We have special baroreceptors in the aorta and carotid artery that can sense changes in arterial stretch and send signals to the medulla
Nerve signals from baroreceptors get sent to the medulla via cranial nerves _ and _
Nerve signals from baroreceptors get sent to the medulla via cranial nerves IX and X
The _ is responsible for regulating blood pressure in the long term
The kidney is responsible for regulating blood pressure in the long term
* Causes us to urinate less when blood volume or blood pressure is low
* Causes us to urinate more when these things are high
* Also controls absorption of NaCl and water
In patients with end-stage kidney disease, we expect to see (increased/reduced) urine output and (high/low) blood pressure
In patients with end-stage kidney disease, we expect to see reduced urine output and high blood pressure
* Rely on dialysis to remove excess fluid
We have separate volume receptors (stretch receptors) in the atria and ventricles that when stretched by high blood volume, release _
We have separate volume receptors (stretch receptors) in the atria and ventricles that when stretched by high blood volume, release natriuretic peptides –>causes renal sodium and water excretion
The greatest density of baroreceptors lies around the _ and _
The greatest density of baroreceptors lies around the aortic arch and carotid sinus
Afferent signals to the brain from baroreceptor stretch is carried by _ and _
Efferent signals back to the heart are carried by _ and _
Afferent signals to the brain from baroreceptor stretch is carried by glossopharyngeal nerve IX and vagus nerve X
Efferent signals back to the heart are carried by sympathetic nerves (traveling via the spinal cord) and parasympathetic nerves (traveling via vagus nerve)
The carotid sinus afferent nerves use _ cranial nerve to transmit signals to the brain
The carotid sinus afferent nerves use glossopharyngeal (CN IX) to transmit signals to the brain
The aortic arch afferent nerves use _ cranial nerve to transmit signals to the brain
The aortic arch afferent nerves use vagus nerve (CN X) to transmit signals to the brain
How do baroreceptors transmit signals?
Baroreceptors will fire on each heartbeat, increasing firing when the heartbeat is faster and decreasing firing when the heartbeat slows
Explain the series of events following baroreceptors signal high blood pressure
- Baroreceptor firing is high because of high BP
- Signals get sent to the medulla
- Signals are then processed in the hypothalamus
- Efferent nerves go to the:
* SA and AV node: to reduce heart rate
* Cardiac myocytes: to reduce contractility
* Arteries: to relax their smooth muscle (dilate) and drop SVR
* Veins: to relax smooth muscle and lower venous pressure and increase capacitance
Carotid massage can be used in situations of _ to cause _
Carotid massage can be used in situations of pathologic tachycardia to cause fooling of baroreceptors –> make the body think there is hypertension –> reduce firing rate
How does the body respond to a decrease in blood pressure?
The _ reflex is a reflex on the “venous side” whereby stretching of the right atrium will cause _
The Bainbridge reflex is a reflex on the “venous side” whereby stretching of the right atrium will cause increase heart rate
* If right atrium stretches it is usually because of volume overload –> tachycardia relieves volume overload by increasing cardiac output
Which cirulating molecules have the effect of lowering blood pressure?
Molecules that lower blood pressure include:
* Natriuretic peptides
* Nitric oxide
* Histmine
* Bradykinin