Regulation of Cardiac Output and Blood Pressure Flashcards
Preload can become raised due to
Fast filling time and increased venous return
Contractility can become raised due to
Sympathetic stimulation
Epi and norepi
high intracellular calcium ions
high blood calcium levels
thyroid hormones
glucagon
Afterload can become raised due to
Increased vascular resistance
Semilunar valve drainage
Preload can be decreased due to
decreased thyroid hormones
decreased calcium ions
high or low potassium ions
high or low sodium
low body temperature
hypoxia
abnormal pH balance
drugs
Contractility can become lowered due to
Parasympathetic stimulation
acetylcholine
hypoxia
hyperkalemia
Afterload can become lowered due to
Decreased vascular resistance
What factors affect heart rate?
Increase (Positive chronotrope)-
Sympathetic input
Hormones, such as thyroid hormone
Decrease (Negative chronotrope)-
Parasympathetic input
Total Peripheral Resistance is a product of these three factors
Blood viscosity
Total blood vessel length
Vessel diameter (main factor)
The amount of blood ejected by each ventricle in 1 minute is
Cardiac output
Equation(s) for CO
CO = HR x SV
CO = BP / TPR
There are four main factors that affect the CO
Heart Rate
Contractility
Preload
Afterload
Equation for Blood pressure
BP = CO x TPR
The SA node is the _____ mechanism for controlling CO.
Intrinsic
Neural control of CO and BP (extrinsic)
Rapid: Neural control of vessel diameter, heart rate, stroke volume
Chemical/hormone control of CO and BP (extrinsic)
Intermediate to long-term:
Renin-Angiotensin II system
Renin-Aldosterone system
Antidiuretic Hormone (ADH)
Three areas of the vasomotor center (neural control)
Vasoconstrictor
Vasodilator
Sensory
Vasoconstrictor Area- Neurons originating here extend down the spinal cord and ____
excite preganglionic sympathetic fibers.
The Sensory Area is Located in the ___
Nucleus of Tractus Solitarius
When needed, the lateral portions of the Vasomotor center transmit _____ to increase heart rate and contractility
excitatory impulses through the sympathetic nerve fibers
Through the Autonomic Nervous System, the Vasomotor Center regulates these three things
HR, SV, and TPR
Sensory info from ____ receptors enters the Nucleus of Tractus Solitarius from ___ and ___
Baroreceptors; Glossopharyngeal and vagus
The rate of firing from the baroreceptors progressively ____ with increasing blood pressure
increases
The Baroreceptor Reflex results in _____ by decreasing sympathetic outflow and increasing parasympathetic outflow from the CNS
decreased blood pressure
When arterial blood pressure falls well below normal, these receptor cells are hypoperfused, resulting in low O2, elevated CO2, and elevated H+. Signals are transmitted via the glossopharyngeal and vagus nerves which excite the Vasomotor Center
Chemoreceptors
Chemoreceptors increase BP due to
increased TPR and increased CO
What is the CNS Ischemic Response?
Decreased blood flow due to hypotension results in increasing levels of CO2 and H+ in the medulla, This has a direct effect of stimulating the sympathetic fibers in the Vasomotor Center, resulting in an increase in blood pressure.
In the RAA System, _____ in the walls of the Afferent Arterioles act as baroreceptors and respond to a drop in blood pressure by releasing Renin
Juxtaglomerular cells
