BIOL122 Lecture Notes - Lecture 4: Renin, Collagen, Healthy Diet
Hypertension and anti- hypertensive drugs
Blood pressure:
• Systolic pressure: 120
- Peak arterial pressure during ventricular systole/ contraction
• Diastolic pressure 80
- Minimum arterial pressure during diastole/ relaxation
• Arterial blood pressure:
- Pulse pressure: difference between systolic and diastolic
pressure 120-80= around 40
- Mean arterial pressure (MAP): average pressure in arteries
during one cardiac cycle
Determinants of MAP: CO(how much blood is ejected by each minute) = HR (beats per
min) X SV (how much blood does the ventricle eject with each contraction)
• Cardiac output:
- Amount of blood ejected by ventricle into artery each minute.
Beats per minute, blood per beat (SV)
• Total peripheral resistance:
- Diameter of arterioles, vasoconstriction (increased resistance)
Control of MAP:
• Cardiac output
- Heart rate and stroke volume: increased SNS and down PNS
• Total peripheral resistance
- Vessel diameter. SNS doesn’t influence blood vessels
- PNS dilates and constricts the blood vessels
Hypertension: is a condition in which the blood vessels have persitenetly raised
pressure. Systolic above 150mmHG is high. Diastolic above 90mmHG is high
Types of hypertension:
• Primary: no identifiable underlying cause. Accounts for 95%
• Secondary: underlying condition: accounts 5%. Kidney disease common
• Pre- eclampsia: associated with pregnancy. Protein in the urine.
Primary hypertension risk factors:
- Cultural background/ race
- Age
- Gender
- Smoking
- Alcohol
- Stress
- Lack of exercise
- Sodium
- Obesity
- Diabetes
Aetiology/ pathogenesis
1. Excess sympathetic activity
2. Overactive RAAS
3. Alerted neurohormonal control
4. Metabolic disturbance
Excessive sympathetic activity: adrenaline released from SNS neurons
• Increase TPR: vasoconstriction. Noradrenaline binds to smooth muscle
• Increase CO: stroke volume, heartrate. Causing the muscles to contract
Overactive RAAS:
• Angiotensin II: vasoconstriction
• Aldosterone: sodium retention and water retention
Altered neurohormonal control:
• Atrial natriuretic peptide
• Released from right atrium
• Promotes sodium excretion
• Mediates vasodilation
Metabolic disturbance
• Insulin resistance
• Increased sympathetic tone
• Elevated angiotensin II activity
Clinical manifestations
• Atherosclerosis
- Ischemic heart disease
- stroke
• Stroke
- Aneurysm bursts
- Small blood vessel bursts
• Organ failure
Pharmacology:
- Vasodilation
- Decrease fluid volume
- Decrease cardiac output
• Determinants of MAP
- Cardiac output (SV X HR)
- Total peripheral resistance
• Decrease heart rate and stroke volume
• Decrease TPR
Beta Antagonists:
• Pharmacodynamics:
- Bind to beta receptor and block NA from binding
• Pharmacokinetics:
- Taken orally
- Metabolized by liver
- Excreted in faeces and urine
• Pharmacological effects
- Decrease sympathetic stimulation
- Decreased heart rate
- Decreased strength of contraction
• Adverse effects
- Hypertension: very low blood pressure
ACE inhibitors:
• What does ACE do?
- Angiotensin I- Angiotensin II
• Pharmacodynamics
- Competitively inhibit ACE
• Pharmacokinetics
- Taken orally
- Metabolized in lover
- Excreted in faeces and urine
• Adverse effects
- Relax tachycardia
- Hypotension
- GI tract
Non- Pharmacological:
- Weight loss
- Salt reduction
- Alcohol reduction
- Diet low in saturated fats
- Diet high in fresh fruit and vegetables
- Increase exercise
- Reduce stress
Document Summary
Peak arterial pressure during ventricular systole/ contraction: diastolic pressure 80. Minimum arterial pressure during diastole/ relaxation: arterial blood pressure: Pulse pressure: difference between systolic and diastolic pressure 120-80= around 40. Mean arterial pressure (map): average pressure in arteries during one cardiac cycle. Determinants of map: co(how much blood is ejected by each minute) = hr (beats per min) x sv (how much blood does the ventricle eject with each contraction: cardiac output: Amount of blood ejected by ventricle into artery each minute. Beats per minute, blood per beat (sv: total peripheral resistance: Heart rate and stroke volume: increased sns and down pns: total peripheral resistance. Pns dilates and constricts the blood vessels. Hypertension: is a condition in which the blood vessels have persitenetly raised pressure. Types of hypertension: primary: no identifiable underlying cause. Accounts for 95: secondary: underlying condition: accounts 5%. Kidney disease common: pre- eclampsia: associated with pregnancy.
