Blood Pressure - L6+L7 Flashcards
1.Normal bp?
2. Elevated bp?
3. Hypertension - high bp: stage 1?
4. Hypertension - high bp: stage 2?
5. Hypertensive crisis - doctor asap?
-> Remember in US guidelines have changed
- Systolic: less than 120 and diastolic less than 80
- Systolic: 120-120, diastolic less than 80
- Systolic: 130-139, diastolic 80-89
- Systolic: 140 or higher, diastolic 90 or higher
- Systolic: higher than 180, diastolic higher than 120
How much of CVS disease is preventable?
80%
CVD deaths every year? and % globally?
18.6 million and 33%
Raised b.p. estimated to cause how many deaths - what % of total of all deaths?
7.5 million deaths and about 12.8% of all deaths
With bp how does risk of CVD double?
The risk of cardiovascular disease doubles for each increment of 20/10 mmHg of blood pressure, starting as low as 115/75 mmHg.
Mean arterial pressure is determined by?
Heart rate, stroke volume and total peripheral resistance
What is total peripheral resistance?
Combined resistance of all blood vessels
MAP = ?
CO V TPR
CO = HR X SV
THUS MAP = HR X SV X TPR
What is arterial pressure?
Systolic Pressure (120 mmHg) - occurs with ventricular contraction
Diastolic Pressure (80 mmHg) - occurs with ventricular refilling
Bp thus 120/80 mmHg
Normotension- state in which arterial bp is within the normal range so what is this value?
BP < 120/80 mmHg
What is pulse difference?
Difference between Sys. P. & Dias. P.
Normally 40 mmHg at rest
What can high pulse pressures at rest be indicative of?
Vascular disease
MAP= diastolic + pulse/3 -> what is it?
Mean arterial pressure - average pressure: regulated pressure
Effect of CO on MAP?
Increase in CO leads to an increase in the volume of blood contained in the aorta and an increase in MAP when TPR remains the same
Effect of TPR on MAP?
A constant cardiac output leads to an increase in the volume of blood contained in the aorta and an increase in MAP when total peripheral resistance increases
What is MAP the driving force for?
MAP is the driving force for blood flow
F = ?
F = Delta P / R
Change in pulse / resistance
What is critical to normal function of bp?
Regulating MAP
If MAP is less than normal, what happens?
Hypotension - inadequate blood flow to tissues
If MAP is more than normal, what happens?
Hypertension - stress on heart and walls of blood vessels
How do you measure bp?
- Recorded at heart level via brachial Artery
Korotkoff sounds via turbulent flow, upon cuff
pressure release - Inflate cuff above expected systolic pressure.
- Slowly deflate cuff: blood flows when BP > cuff P
- Generates Korotkoff sounds.
- Clear tapping audible via stethoscope-> Indicates Systolic Pressure
- Diastolic pressure indicated at disappearance
of muffled sound
What indicates systolic pressure?
What indicates diastolic pressure?
Clear tapping audible via stethoscope-> Indicates Systolic Pressure and Diastolic pressure indicated at disappearance of muffled sound
Short term regulation of MAP from seconds to minutes:
1. Mainly what control?
2. Involves what?
3. Regulates?
- Primarily neural control
- Involves heart and blood vessels
- Regulates CO and TPR
Long term regulation of MAP from minutes to days:
1. Control?
2. Involves?
3. Regulates?
- Primarily hormonal control
- Involves kidneys
- Regulates blood volume
Neural control of MAP:
1. Feedback?
2. Detectors?
3. Integration center?
4. Controllers?
5. Effectors?
- Negative feedback loops
- Baroreceptors
- Cardiovascular centers in the brainstem
- Autonomic nervous system
- Heart and blood vessels
Another word for baroreceptors?
Stretch receptors
What are arterial baroreceptors?
High pressure baroreceptors
Sinoaortic baroreceptors
Where are the arterial baroreceptors located?
Carotid sinus and aortic arch
CV Control Center:
Medulla oblongata-> Integration center for blood pressure regulation
Output via Sympathetic nervous system and Parasympathetic nervous system
Location of cardiac and venous (low-pressure) baroreceptors?
Walls of large systemic veins and walls of the atria
Low pressure baroreceptors = volume receptors
What does a decrease in blood volume do?
Decrease in blood volume activates receptors
triggering responses that act in parallel with
baroreceptor reflex
Treatment of hypertension: 7
- Non-pharmacological: lifestyle changes, salt restriction, diet, weight loss, exercise, smoking, alcohol
- Drug treatment: antihypertensives: goal of use is to prevent endpoints ie MI, stroke
- Thiazide diuretics: Inhibit Na+/K+/Cl- exchange in distal renal tubule
- b-blockers: Reduce HR & contractility
- a-blockers: Reduce sympathetic tone; dilate arteriolar smooth muscle
- Mixed a-& b-blockers
- L-type Ca2+ channel blockers: relaxation of vascular smooth muscle
→reduced resistance
Where does parasympathetic input go to and what does this cause?
SA node (decrease HR) and AV node
Where does sympathetic input go to and what does this cause?
SA node (increase HR), AV node, Ventricular myocardium (increase contractility), Arterioles (increase resistance) and Veins (increase venomotor tone)
What is the baroreceptor reflex?
Negative feedback loop to maintain blood pressure at normal level
Components of baroreceptor reflex?
1. Detectors?
2. Afferent?
3. Integration center?
4. Efferents?
5. Effectors?
- Detectors = baroreceptors
- Afferents = nerves
- Integration center = cardiovascular control
center - Efferents = autonomic nervous system
- Effectors = heart, arterioles, veins
What are baroreceptors, what do they indirectly respond to?
Specialised nerve endings that respond to stretch of vessel wall
Indirect response to changes in BP
Explain the types of baroreceptors?
Type: A fibres (myelinated)
Low pressure (30-90 mmHg)
Important at rest
Type: C fibres (unmyelinated)
High pressure (70-140 mmHg)
Increasingly active at higher pressures
What happens to baroreceptors in hypertension?
They reset within 1-2 days
Baroreceptors - short/long term?
Baroreceptors respond well to short term
(moment-to-moment) changes
Not important for long-term regulation of BP
Example of baroreceptor reflex in action - a person who had been lying down stands up quickly what is happening?
—-Gravity causes venous pooling in the legs.
– This causes a decrease in VR, causing a decrease in CO
– This causes a decrease in blood pressure.
– Baroreceptors sense the decrease: reflex occurs
– The reflex causes increased sympathetic and decreased parasympathetic activity.
– CO and TPR are increased.
– Blood pressure is increased back to normal.
EXAM Q describe understanding of hypertension in terms of population data, blood pressure, What are the determinants of it, how is it regulated and treated
Baroreceptors, CNS and CVS control involves integrated responses from several brain regions:
1. Baroreceptor input?
2. Output from NTS?
- Baroreceptor input to NTS in medulla (nucleus tractus solitarius)
- Output from NTS to:
- Parasympathetic NS (vagus) via nucleus ambiguus = Cardiac control (limits HR)
- Sympathetic NS via rostral ventrolateral medulla
= Cardiac and blood vessel control (↑ed contractile strength/tone)
- Hypothalamus & amygdala
Allows these areas to override the baroreceptor reflex during stress:
Allows a stress-associated increase in BP to occur
EXAM Q - Tell me about understnding of anatomy and physiology of reg of heart rate?
Describe SA + AV node, internodal pathways, what controls it, sympathetic control and effect
What does hemorrhage cause?
Hemorrhage causes:
– Baroreceptor reflex
– Increase in sympathetic activity
– Decrease in parasympathetic activity
Baroreceptor reflex in GI tract and Brain with hemorrhage and blood low?
GI tract:
* Increased resistance
* Decreased blood flow
Brain:
* Vasculature not subject of extrinsic control
* No change in resistance
* Blood diverted from GI tract to brain
Hormones control MAP such as adrenaline:
1. Where is it released?
2. What does it do to MAP?
3. It acts on heart how?
4. Acts on smooth muscle of arterioles to do?
5. What does it do to smooth muscle of veins?
- Released by adrenal medulla in response to sympathetic activity
- Increases mean arterial pressure
- Acts on heart: Increases HR and SV
- Acts on smooth muscle of arterioles
– Increases TPR - Acts on smooth muscle of veins
– Increases venomotor tone
Extra inputs to CVS?
Bainbridge reflex and atrial stretch receptors
- Bainbridge reflex?
- Atria stretch receptors?
- Vena cava stretch receptors → neural mediated ↑HR
Avoids venous congestion - Myelinated vagal afferents sensitive to blood volume -Located at junction of great veins and atria
NB some hormones are also vasoactive – mainly as vasoconstrictors to increase TPR
Controls influence endocrine regulation of blood volume via?
Hypothalamic ADH → renal water retention
Renin-Angiotensin-aldosterone system (RAS)
→ renal salt & water retention
Atrial Natriuretic Peptide → renal salt & water excretion
What do vasopressin and angiotensin 2 do, what are they?
Increase TPR and MAP
They are vasocontrictors
Ideal CV Health 4 behaviours and 4 health indicators?
4 Behaviours
* Not Smoking
* 5 x Fruit and Veg
* Physical Activity x 150 mins
* Alcohol < than 8 drinks per
week
4 Health Indicators
* Blood Pressure
* Cholesterol
* Weight – BMI
* Blood Sugars
SEE Angiotensin and renin diagrams slides
Learn the pathways
exam Q explain angiotensin pathway?
Angiotensinogen -> angiotensin 1 -> angiotensin 2 -> angiotensin 2 type 1 receptor
**Angiotensin 2 biologically active form that stimulates blood pressure
Renin and ACE inhibitors -> pharmaceuticals
