Transcript Blood Pressure and Hypertension - The Bronx High School of Science

Blood Pressure and
Hypertension
Blood Pressure
Your Blood Pressure Reflects:
1) How hard your heart is working
2) The condition of your arteries
Cardiac Output x Arterial
Resistance
• Cardiac Output = Amount of blood
your heart pumps per minute
• Arterial Resistance = Pressure
the walls of the arteries exert on
the flowing blood
What regulates your blood
pressure?
• Complex interactions among your central
nervous system (CNS), hormones, and
substances your blood vessels produce
from the endothelium
• Endothelium = layer of cells lining the
inner wall of blood vessels; produce both
vasodilators and vasoconstrictors
What happens when blood
pressure gets too high?
• Nerve cells in your circulatory system tell
your autonomic nervous system (ANS)
• ANS – manages involuntary activities of
smooth muscles, including those in the
intestines, sweat glands, airways, heart
and blood vessels
Autonomic Nervous System
• The ANS is made of the sympathetic and
parasympathetic nervous systems
The SYMPATHETIC nervous system:
- Prepares body for action
- Triggers release of neurotransmitters
epinephrine and norepinephrine
- Raises blood pressure
Autonomic Nervous System
• The ANS is made of the sympathetic and
parasympathetic nervous systems
The PARASYMPATHETIC nervous system
helps the body recover from action
How is blood pressure measured?
• Sphygmomanometer – traditional blood
pressure measuring device; measures in
mm Hg (mercury)
Systolic pressure = top #, amount of
pressure during the heart’s pumping
phase (systole)
Diastolic pressure = bottom #, amount of
pressure during resting phase between
heartbeats (diastole)
Classifications of Hypertension
ESSENTIAL HYPERTENSION (Primary
hypertension)
- 90-95% of cases
-condition has no identifiable cause
Classifications of Hypertension
SECONDARY HYPERTENSION – arises from
other condition; often treatable
Common causes
1) Renal artery stenosis – narrowing of artery that
supplies blood to the kidneys
2) Hyperaldosteronism – too much aldosterone, a
hormone made by the adrenal glands that
regulates potassium and sodium levels
Secondary Hypertension
3) Hyperthyroidism – overactive thyroid
gland
How High is High Blood Pressure?
See your handout for information on:
-Prehypertension
-Stage 1 Hypertension
-Stage 2 Hypertension
Risk Factors for Hypertension
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Race
Family history
Age
Sex
Risk Factors for Hypertension
• Cigarette smoking
• Heavy alcohol consumption
• Diet (too much salt, saturated fat, and
calories; not enough fruits and vegetables)
• Obesity and overweight
• Inactivity
• Stress