CVS Regulatory Centers & ABP & Its Determinants Flashcards
Mention site of CVS centers
Medulla oblongata & lower pons (brainstem)
Mention supply and function of VMC
Supplies whole heart, blood vessels & adrenal medulla
Origin of noradrergic sympathetic innervation, it is excitatory to heart & responsible for vasomotor tone on arterial system.
Describe function & supply of CIC
It supplies atria only (vagal escape) & some blood vessels
It is responsible for parasymoathetic inhibitory vagal tone (supply) to heart
The VMC synapses in spinal cord at level of ….
Thoracolumbar segments ( T1 to L2 or L3)
Mention parts of CIC
Nucleus ambiguous
Dorsal nucleus of vagus nerve
Mention oarts of VMC & their functions
Pressor area: in dorsolateral medulla, responsible for continous discharge in sympathetic noradrenergic fibers.
Depressor area: caudal & ventromedial to pressor area, inhibitory to pressor area thus dec discharge in symoathetic niradrenergic fibers.
The main sensory component of CVS centers is ….
Nucleus tractus solitarus
Mention effects of stimulation of pressor area & depressor area
Pressor
1. Arteriolar VC
2. Increased heart rate & contractility
3. Inc release of catecholamines from adrenal medulla
4. Reciprocal decrease in activity of depressor area
Depressor is opposite
Mention the inhibitory afferents and their action
Stimulate the depressor center
- Baroreceptors (aortic arch & carotid sinus & cardiopulmonary receptor) via NTS
- Cerebral cortex : in grief
- Severe pain or prolonged visceral pain
- Lung inflation, VD & dec ABP, mediated by vagus
Mention the excitatory afferents and their action
Stimulate pressor area & inhibit depressor
- From chemoreceptors inc PaCO2 or dec PaO2 BY AORTIC & carotid bodies via NTS
- Mild to moderate pain from skin
- Cerebral cortex in excitement & anger
- During muscular exercise
Cerebral cortex interacts with CVS centers via …..
Hypothalamus
The sensory afferents in muscular exercise interact with CVS centers via
Reticular formation
The VMC is directly stimulated by ….&….
High CO2 or low O2 (low)
Describe Cushing’s reflex
Increased intracranial pressure stimulated VMC directly
The main cardiac component affected by CIC
SA node
Mention functions of ABP
- ABP is the driving force responsible for blood flow through different arteries to all tissue & organs ensure adequate perfusion
- ABP is responsible for opening arteries
- ABP is responsible fir exhange by filtration across capillary pores
- ABP is responsible for GFR for urine formation.
MAP = …..
DBP + (SBP-DBP)/3
Decribe effect if gravity on ABP
ABP Is measure in brachial artery on level of heart. In vertical position, any artery above above heart level shows dec & any artery below heart shows inc in ABP by factor if 0.77 mmHg for each 1 cm height.
Decribe effect if distance from heart on ABP
Elasticity dec with inc distance from heart, so SBP & PP are inc while DBP are dec.
Mention effect of age & sex
Age: in newoborns it is 30-50 mmHg, increased to normal value in adulthood. With progressive age, elasticity dec so SBP inc & DBP dec, inc PP.
Sex: dec in females due to sex hormones, equalize at menopause.
Describe nocturnal & diurnal variation
At early morning its is least, rises slightly by afternoon, dec again at night at least by 10 mmHg due to parasympathetic activity.
Describe effect of exercise & body position
SBP is inc in all types of exercise, DBP & MAP is slightly dec in isotonic exercise, but both are inc markedly by isometric exercise.
Sitting/recumbent position is dec by 15 mmHg upon standing
Define static component of pressure & its value
It is the pressure of blood in the arterial system without pumping force of heart. It is determined by the total volume of blood and the total capacity of CVS when heart is arrested
7-8 mmHg
Define dynamic component of pressure & its value
Pressure generated by pumping force the heart
About 90 mmHg
Mention factors affecting ABP
- COP
- TPR
^^^most important - Total blood volume
- Capacity if vessels
- Elasticity of aorta & large arteries
CO represents ….. while TPR represents ……
Inlfow of blod into arterial system
Outflow of blood from arterial system
Mention determinants of MAP
CO & TPR
Decsribe effect if increased SV
Inc SBP, MAP & PP
Describe effect if inc HR
Inc DBP & MAP
but dec PP
Decsribe effect of inc TPR
Inc DBP primarily but SBP & MAP are also inc
Mention the componenys of TPR
- Length of vessel
- Viscosity of blood
- Diameter of vessel
TPR =
8 nL/ pi*r^4
GR: There is no friction resistance between the vessel wall & first layer of blood
Since it doesn’t move at all
Viscosity is inc ….&…., dec in ….
Polycythemia & inc Igs
Anemia
Determinants of PP
SV
Elasticity of arterial system
What is the most imp mechanism of regulation of ABP
Change in diameter of arterioles
What is the function of elasticity of arterial system
Prevent excessive rise of SBP during rapid ejection phase, and prevent excessive fall of DBP during diastole
Determinants of SBP
SV
Elasticity of aorta & big arteries
Determinants of DBP
TPR
Normal elastic recoil of aorta & large arteries
An intact aortic valve
Factors that inc PP
SV, loss of elasticity of aorta & large arteries & incompetent aortic valve
Effects of loss of elasticity
Inc SBP, dec DBP, inc PP
