chapter 11 – part 5 the cardiovascular system. vital signs the following measurements are...
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Chapter 11 – Part 5The Cardiovascular System
Vital SignsVital Signs
The following measurements are referred to collectively as vital signs in clinical settings: • Arterial pulse• Blood pressure• Respiratory rate• Body temperature
Vital signs are a fairly good indication of the efficiency of a person’s circulatory system
PulsePulse
Pulse – Pressure wave of blood Is created from the
alternating expansion and recoil of an artery that occurs with each beat of the left ventricle
Pressure PointsPressure Points Monitored at pressure
points where pulse is easily palpated Can feel a pulse where an
artery lies close to the body surface
Are called pressure points because these same points are compressed to stop blood flow during hemorrhage
PulsePulse
Normally pulse rate (pressure surges per minute) equals heart rate (beats per minute).
Pulse averages 70-76 beats per minute in a normal resting person.
Pulse is influenced by activity, postural changes, and emotions.
How to Take a PulseHow to Take a Pulse
Place the tips of your first two or three fingers over one of the arteries designated as a pressure point.
Compress the artery firmly as you begin and then immediately ease up on your pressure slightly.
Blood PressureBlood Pressure
Blood Pressure – The pressure the blood exerts against the inner walls of the blood vessels It is the force that keeps blood circulating
continuously even between heartbeats
Any system equipped with a pump that forces fluid through a network of closed tubes operates under pressure.
Understood to mean the pressure within the large systemic arteries near the heart
Blood Pressure GradientBlood Pressure Gradient
Blood flows along a pressure gradient (from high to low) as it makes its circuit. Pressure is highest in the large arteries and
continues to drop throughout the pathway, reaching zero or negative pressure at the venae cavae
The high pressure in these arteries forces the blood to continually move into areas where the pressure is lower.
Comparison of Blood Pressures in Different Comparison of Blood Pressures in Different VesselsVessels
Blood Pressure GradientBlood Pressure Gradient
The pressure differences between arteries and veins are apparent when the vessels are cut: If a vein is cut - the blood flows evenly
from the wound If an artery is cut - rapid spurts of blood
Blood Pressure GradientBlood Pressure Gradient
The continual flow of blood absolutely depends on the stretchiness (elasticity) of the large arteries and their ability to recoil and keep the pressure on the blood. Garden hose example with hard walls:
When the water hose is turned on, the water spurts out under high pressure because the hose walls don’t expand.
When the faucet is suddenly turned off, the flow of water stops because the walls cannot recoil to keep pressure on the water. The pressure drops and the flow of water stops.
Measuring Blood PressureMeasuring Blood Pressure
Two arterial blood pressure measurements are usually made:1. Systolic Pressure – Pressure in
the arteries at the peak of ventricular contraction
2. Diastolic Pressure – Pressure in the arteries when the ventricles are relaxing
• Blood pressures are reported in millimeters of mercury (mm Hg)
Measuring Blood PressureMeasuring Blood Pressure
A blood pressure of 120/80 indicates a: Systolic pressure of 120
mm Hg Diastolic pressure of 80
mm Hg
Measuring Arterial Blood PressureMeasuring Arterial Blood Pressure
Blood Pressure: Effects of FactorsBlood Pressure: Effects of Factors
Arterial blood pressure is directly related to the two following factors. An increase in the following factors causes an increase in blood pressure.
1. Cardiac output (the amount of blood pumped out of the left ventricle per minute)
2. Peripheral resistance
Blood Pressure: Peripheral ResistanceBlood Pressure: Peripheral Resistance
Peripheral Resistance – The amount of friction encountered by the blood as it flows through the blood vessels It is increased by the
constriction, or narrowing, of the blood vessels.
Increased blood volume or thickness (viscosity) increases peripheral resistance.
Blood Pressure: Effects of FactorsBlood Pressure: Effects of Factors
Many factors can alter blood pressure. Some of the factors include: Age Weight Time of day Exercise Body position Emotional state Various drugs
Blood Pressure: Effects of FactorsBlood Pressure: Effects of Factors
1. Neural Factors: Autonomic Nervous System Sympathetic nerves cause vasoconstriction, which
increases blood pressure back to homeostatic levels This hopefully increases venous return so circulation can
continue. During exercise:
There is a general vasoconstriction except in the skeletal muscles.
The vessels of the skeletal muscles dilate to increase the blood flow to the working muscles.
Blood Pressure: Effects of FactorsBlood Pressure: Effects of Factors
2. Renal factors Regulates blood pressure by altering blood volume
As blood volume decreases, blood pressure decreases.
As blood volume increases, blood pressure increases.
Blood Pressure: Effects of FactorsBlood Pressure: Effects of Factors
3. Temperature Heat has a vasodilation effect
Warm compresses are used to speed the circulation into an inflammed area
Cold has a vasoconstricting effect Why cold compresses are
recommended to prevent swelling of a bruised area
Blood Pressure: Effects of FactorsBlood Pressure: Effects of Factors
4. Chemicals Various substances can cause increases or decreases
Nicotine increases blood pressure by causing vasoconstriction
Alcohol causes vasodilation and decreases the blood pressure; often become flushed after drinking alcohol
5. Diet• A diet low in salt, saturated fats, and
cholesterol helps to prevent high blood pressure
Factors Determining Blood PressureFactors Determining Blood Pressure