College of Health SciencesDepartment of Medical Physiology

Advanced Cardiovascular PhysiologyPresentation on

Hypertension

By Teketel Eristu 1

Presentation Outline Introduction

Blood Pressure

High Blood Pressure/Hypertension

Causes of Hypertension/Risk Factors

Types of Hypertension

Regulation of HBP/HPN

Prevention and Treatment of HPN

Animation of HPN, Video

References 2

ObjectivesAt the end of the Presentation the Learners are expected to:

Discuss about Blood Pressure

Explain High Blood Pressure/ Hypertension in detail

Classify Hypertension and Causes

Explain the Consequences of Hypertension

Discuss the regulation of Hypertension

Explain Treatment of Hypertension

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1. Introduction

Blood Pressure

- is the pressure exerted by circulating blood upon the walls of blood

Vessels

-decreases as the circulating blood moves away from the heart

- expressed in terms of the systolic pressure over diastolic pressure

(mmHg). Or it makes Lup Dup major sound

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Lub

If you listen to your heartbeat, it makes a lub dub sound.

The lub is when blood is

pushed out of the heart into

the body and the dub is the

reloading of the heart with

more blood ready to push it

out to the body

Dub

5

Cont..

Blood pressure is an important characteristic of our body.

Without blood pressure, nutrients, oxygen, and proteins could not travel

from the arterial side of the body to the venous side.

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Cont…

Normal Blood Pressure

95/65 mmHg=1 Years

100/65 mmHg=6-9 years

110/65-140/90mmHg= Adults

-its Average Physiologic Value (normal BP) = 120/80 mmHg

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Cont…

If blood pressure is chronically elevated a condition is known as

hypertension

According to medical dictionary, hypertension means "High blood

pressure; transitory or sustained elevation of systemic arterial blood

pressure

A consistent blood pressure of 140/90 mm Hg or higher is considered

high blood pressure.

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Cont…

• Isolated Systolic Hypertension is Systolic BP elevation in the absence

of elevated diastolic Blood Pressure .

• Isolated Diastolic Blood Pressure is Diastolic BP elevation in the

absence of Systolic BP.

• Accelerated Hypertension / Malignant Hypertension occurs when BP

elevates extremely .

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Table.1. Classification of Blood Pressure for Adults =>18 Years old

Category Systolic mmHg Diastolic mmHg

Hypotension <90 <60

Desirable/Normal 90-119 60-79

Prehypertension 120-139 80-89

Stage 1/Mild Hypertension 140-159 90-99

Stage 2 / Moderate Hypertension

160-179 100-109

Hypertensive Crisis/ stage 3/ Severe/HYN

=> 180 =>110

Isolated Systolic HYN =>140 <90

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2. Types of Hypertension

is abnormal elevation of pulmonary

artery BP.

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Cont…

• Pulmonary blood pressure is normally a lot lower than systemic blood

pressure.

• Normal pulmonary-artery pressure is about 14 mm Hg at rest.

• If the pressure in the pulmonary artery is greater than 25 mm Hg at

rest and 30 mm Hg during exercise, it is abnormally high and is called

pulmonary hypertension.

• Broadly Classified as Primary or Secondary Hypertension 12

Cont…

• Primary pulmonary hypertension

• When not accompanied by underlying heart and

lung disease or other illnesses, it is called primary

pulmonary hypertension.

13

Con….

Secondary pulmonary hypertension

If a pre-existing disease triggered the PHT

e.g. Congenital heart defects

Intracardiac left-to-right shunts :

Heart valve conditions : mitral stenosis

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Cont….

• Typically "blood pressure," "high blood pressure" and "hypertension"

refer to the systemic pressure throughout your body.

Hypertension is classified as either primary (essential)

Idiopathic / hypertension or secondary hypertension

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a) Primary or Essential Hypertension

About 90–95% of cases are categorized as "primary

hypertension," which means high blood pressure with no

obvious/direct medical cause.

-is the most prevalent hypertension type

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Cont..Although no direct cause has been identified, there are many factors

such as sedentary lifestyle, smoking, stress, visceral obesity,, salt

(sodium) sensitivity, alcohol intake, and vitamin D deficiency, aging,

some inherited genetic mutations and having a family history of

hypertension, an elevated level of renin, sympathetic nervous system

over activity…etc. increase the risk of developing primary

hypertension.17

b) Secondary Hypertension

About 5–10% of cases (Secondary hypertension) are caused by other

conditions that affect the kidneys, arteries, heart or endocrine

system.

Thus, results from an identifiable cause.

but: may come to normal values by treatment.

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Cont…This type is important to recognize since it's treated differently to essential

hypertension. Facrors that cause this type of HYN

1. Adrenocortical hyperfunction

Primary hyperaldosteronism

Cushing Syndrome

Congenital or hereditary adrenogenital syndromes

(17a-hydroxylase and 11b-hydroxylase defects)

2. Pheochromocytoma

3. Severe Polycythemia 19

Cont…4). Renal Diseases

It is common for all types of chronic kidney disease to eventually cause

hypertension (approx. 80% of chronic kidney disease patients

develop hypertension at some point). This is due to fluid retention in

the body, due to poor elimination of fluids and poor control of

sodium

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Cont….

Glomerulonephritis (chronic renal inflammation )

Polycystic renal disease-is cystic genetic disorder of the kidneys

Tumors of JG Cell- Renin-producing tumors

Renovascular stenosis or renal infarction (Reno vascular

hypertension)------RAS

Hyperparathyroidism and Calcium overload leads to renal failure and

hypertension

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Cont…

5) Neurogenic hypertension

Polyneuritis ( lead poisoning…..) inflammation of Peripheral

nerves

Increased intracranial pressure

Arterial occlusion

Tumors

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Cont….Others

Coarctation of aorta BP in upper parts of body, i.e. above

obstruction.

Hypercalcemia

Medications, e.g., glucocorticoids, …etc

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Consequences of Hypertension: Organ Damage

CHF=congestive heart failure; CHD=coronary heart disease; LVH=left ventricular hypertrophy.

Chobanian AV et al. JAMA. 2003;289:2560-2572.

Hypertension

LVH, CHD, CHF

Chronic kidney diseaseRetinopathy

Transient ischemic attack, stroke

Peripheralarterialdisease

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Regulation of HBP/HPN

Introduction:

Blood Pressure is regulated within a narrow Range

If the blood pressure is too low:

Inadequate perfusion of organs

If the Blood pressure is abnormally high:

Heart diseases, Vascular diseases ,strokes….

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Cont…The Baroreceptor reflex functions to restore blood pressure back to

normal values whenever the blood pressure deviates from the

normal range. The homeostatic mechanism involves a negative

feedback loop to minimize and oppose any changes in Blood

pressure.

i.e. An increase in BP reflexively causes the BP to decrease and vice

versa.

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What is a Baroreceptor?

Stretch –sensitive

Mechanoreceptors

Located in the Carotid Sinus

and aortic arch

Monitor the pressure of

blood flow to brain and

body

Action potentials are fired

continuously at normal

blood pressureFig. 1 Location and innervations of arterial Baroreceptor

High pressure baroreceptors respond to stretch in the aortic arch and carotid sinus.

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Pathway

Increase in BP stretches the

baroreceptors and increase the

firing rate in the afferent nerves

Glossopharyngeal nerve and

Vagus nerve

This leads to the excitation of the

nucleus tractus solitarius(NTS) in

the Medulla, which inturn inhibits

the vasomotor center via

interneurones. 28

Cont…

The inhibition of the vasomotor center

decrease the sympathetic output and

causes vasodilation, bradycardia,

decrease in CO & fall in BP

The excitation of NTS also stimulates the

Vagus nerve which decrease the HR

& CO29

Baroceptors

with increased P

Medulla

Heart and

Blood Vessels

Nucleus tractus solitarius

Cardiac

decelerator

Cardiac

accelerator

Vaso

constrictor

Sinoatrial

node

Contract-

ility

Arterioles Veins

Carotid

sinus

baroceptors

Aortic arch

baroceptors

Vagus nerveCarotid sinus nerve

glossopharyngeal nerve

Heart Blood vessels

+ +

+ -

Dilation

- - 30

Blood Pressure Regulation

Baroreceptors

Afferent nerves

Medulla oblongata center

Sympathetic efferents

SA node, ventricles,

Arteriolar smooth muscle

Venous smooth muscle

Fig 2 Components of the Baroreceptor Reflex

• Main coordinating center is in the medulla oblongata of the brain; medullary cardiovascular control center

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Regulation of Blood Pressure

Figure 3 T he baroreceptor reflex: the response to increased blood pressure32

Fig.4 Blood Pressure control includes rapid responses from cardiovascular system and slower responses by the kidneys

When the body contains too much EC fluid, the arterial pressure rises. This increase in pressure causes the kidneys to excrete the excess fluid, until pressure returns to normal (pressure diuresis).

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5.Prevention and Treatment of Hypertension

ACE Inhibitors Drugs inhibit the enzyme converting angiotensin into

angiotensin II. Acts as vasodilators of both resistance and capacitance

vessels. Thus, blood vessels relax and blood flow freely.

Angiotensin II receptor blockers

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Cont….Diuretics work on the kidney to remove exess water and fluid from body to

lower BP.

Beta blockers-: Competitively inhibit the binding of catecholamines to

beta-adrenergic receptors

Calcium Channel Blockers- Decrease calcium influx into cells of vascular

smooth muscle -causes the blood vessel to relax and widen.

Nervous system inhibitors- slow nerve impulses to the heart.

Vasodilators- cause blood vessel to widen, allowing blood to flow more freely.

Alpha Blocker- blocks an impulse to the heart causing blood to flow more

freely.35

Cont….Minimize Alcohol

Alcohol raises blood pressure and can harm liver, brain, and heart

• Quite Smoking/ Stop

• Smoking damages blood vessel walls and causes early hardening of the arteries. Nicotine narrows your blood vessels and forces your heart to work harder

Be Physically Active/Exercise

Blood pressure rises as weight rises. Obesity is also a risk factor for

heart disease

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5. References

1. Fauci, Braundwald, Kasper and et al, Harrison’s principles of internal

medicine, 17th edition, 2008, McGraw Hill publisher

2.Pearson International Edition Human Physiology An Integrated

Approach 5th Edition.

DEE UNGLAUB SILVERTON

3 .ww.americanheart.org/presenter.jhtml?identifier “High Blood

Pressure”

4.Different internet sources

5. Lecture Note of Cardiovascular Physiology, Prof. Yekoya A. 2011

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THANK YOU

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