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42 Cards in this Set
- Front
- Back
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What is SYSTEMIC BLOOD Pressure?
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Fluid driven by a pump through a closed circuit operating under pressure. The nearer the fluid is to the pump the greater the pressure exerted on the fluid.
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What is ARTERIAL BLOOD Pressure?
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1 - How much the elastic arteries close to the heart can be stretched.
2 - the volume of blood forced into them at any time. |
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What is ARTERIAL BLOOD Pressure made up of?
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Systolic Pressure + Diastolic Pressure + Pulse Pressure + Mean Arterial Pressure (MAP)
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What is CAPILLARY BLOOD Pressure?
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Capillaries are fragile. High pressure would rupture them & most are extremely permeable.
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What is VENOUS BLOOD Pressure?
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Venous blood pressure is steady & changes very little during cardiac cycle. Low Blood force.
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BP is regulated by manipulating 3 mechanisms, name them
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1 - Cardiac output
2 - Peripheral Resistance 3 - Blood volume |
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What increases Heart Rate (HR)
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Adrenalin
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Which lasts longer, diastole or systole?
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Diastole
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What is important in regulating BP
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Heart Rate
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Define Systolic Blood Pressure
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EJECTING FM HEART
Heart muscles contract & pump blood fm the chambers into the arteries |
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What is the expected value for Systolic Blood Pressure?
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120mm Hg in healthy adults
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Define Diastolic Blood Pressure
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ENTERING HEART
Heart muscles relax and allow the chamber to fill with blood. |
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What is the expected value for Diastolic Blood Pressure?
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about 70 -80mm Hg in healthy adults
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Define Pulse Pressure
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FORCE AT WHICH BLOOD ENTER'S ARTERIES
The difference between Diastolic & Systolic Pressure. Felt as a throbbing pulsation in an Artery (a pulse) during systole. |
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What is the expected Pulse P value?
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BP 120/80 : 120 - 80 = 40 is the pulse pressure
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Define MAP (Mean Arterial Pressure)
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PRESSURE OF BLOOD ENTERING TISSUES
The pressure that propels the blood to the tissues. about equal to the diastolic pressure + 1/3 of the pulse pressure. |
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What is the expected MAP value?
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120/80 : 120-80=40
80 + (40 divided by 3=13) = 93 is the MAP |
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Explain the relationship between blood pressure, blood flow & resistance
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- the pumping action of the heart generates BLOOD FLOW
- PRESSURE results when flow is opposed by RESISTANCE |
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Define blood flow
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Cardiac output (CO) volume of blood through a vessel or organ
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Define blood pressure
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force exerted on the vessel wall by the blood
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define resistance
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opposition to flow, measure of the amount of friction blood encounters as it flows through a vessel
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List the factors that influence blood pressure
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- Cardiac output - heart stops BP drops
- peripheral resistance - clear blood vessels = less peripheral resistance blocked blood vessels = more peripheral resistance - Blood volume = dehydration or bleed out = loss of blood = reduced pressure |
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How may blood pressure be increased?
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by increasing cardiac output or increasing resistance
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How can CO be increased?
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by raising either Heart Rate or Stroke Volume
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What are the kidneys really good at, as far as BP is concerned?
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controlling BP
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what is CO (cardiac output) made up of?
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HR (heart rate) x SV (stroke volume)
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name 2 ways in which SV can be increased
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- increased preload = increased venous return
- increased sympathetic stimulation |
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name 2 ways in which Peripheral resistance may be increased
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- decreased diameter of blood vessels (vaso constrict)
- reducing blood flow to non essential organs |
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Name 2 SHORT term BP maintenance methods
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- Neural
- Hormonal, Renal |
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What is Neural Mechanism?
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- maintaining BP : negative feedback
- receptors : baroreceptors - Control centre : medulla - Effectors : heart & blood vessels |
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What does low BP cause the release of?
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Adrenalin & Noradrenalin from adrenal madulla
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What does Adrenalin & Noradrenalin do?
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Increases Resistance & Cardiac output
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Name 1 long term BP maintenance method
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Renin - angiotensin mechanism
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What happens when Arterial BP declines?
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the kidneys release RENIN into the blood
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What does Aldosterone do?
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it is a hormone that enhances renal reabsorption of sodium, where sodium goes water follows, as a result, blood volume is conserved
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what does ADH promote?
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more water reabsorption
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Define AUTOREGULATION
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automatic adjustment of blood flow to each tissue as per that tissues requirements
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What factors cause autoregulation changes?
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Organs regulate their own blood flow by varying the resistance of their arterioles. EG during sports the muscles & brain need more blood than the stomach, so the stomach gets "put on hold"
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What is Metabolic Control?
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based on chemical demands
- decreased O2 & nutrients stimulate arterioles to dilate - inflammatory chemicals vasodilation |
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What is Myogenic controls?
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based on stretch
- vascular smooth muscle contracts or relaxes depending on stretch of wall *** reduced stretch = vasodiolate |
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What is Myogenic control?
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based on stretch
- vascular smooth muscle contracts or relaxes depending on stretch of wall *** reduced stretch = vasodiolate |
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Explain how Blood flow is REGULATED in the body
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Metabolic controls & Myogenic controls
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