march 26-27, 2014. pulse points areas where can easily feel pulse also act as pressure points....
TRANSCRIPT
Pulse PointsAreas where can
easily feel pulseAlso act as
pressure points. Compressing
these points will reduce downstream blood flow
useful when dealing with major wounds.Try to find several of these!
Blood PressureBlood pressure is the pressure the blood
exerts against the inner walls of the blood vessels.
Usually, we refer to the pressure of the arteries.
Blood PressureBlood pressure is the pressure the blood
exerts against the inner walls of the blood vessels.
Usually, we refer to the pressure of the arteries.
Why does blood pressure drop so low in the capillaries?1) Because there are
so many more capillaries
2) So that the flow of blood will slow to facilitate exchange of materials
Blood PressureBlood pressure is the pressure the blood
exerts against the inner walls of the blood vessels.
Usually, we refer to the pressure of the arteries.
Why do we record blood pressure as two numbers?
Blood pressure in the arteries fluctuates with the cardiac cycle.
Blood PressureSystolic pressure occurs due to ventricle
contractionDiastolic pressure occurs when ventricles
relax
Measuring Blood Pressure1. A
sphymomanometer is placed over the brachial artery.
2. The cuff is inflated to ~150 mmHg (above systolic pressure)
3. Air pressure is slowly released from cuff while a stethoscope is used to listen for Korotkoff sounds in the artery.
Measuring Blood PressureKorotkoff sounds
• Cuff pressure > systolic pressure
there is no blood flow through artery NO SOUNDS
• Cuff pressure = systolic pressure
blood begins to flow turbulently through artery TAPPING SOUND BEGINS
• Cuff pressure = diastolic pressure
blood begins to flow smoothly SOUNDS DISAPPEAR
Test yourself! (Start at ~3:30)
Factors which affect BPIncreased cardiac output (heart rate & stroke volume)
increases blood pressureExerciseStress / Sympathetic nervous system
Increased peripheral resistance (friction of blood traveling through vessels) increases BPAtherosclerosisConstriction of blood vessels (due to sympathetic
nervous system, cold, chemicals such as nicotine)Number of vessels (body size / fat / pregnancy)
Increased blood volume increases blood pressureKidney problems
Which factors will decrease BP?
Resting Blood PressureHypotension is low blood pressure.May cause dizzy
spells, especially when rising
Not problematic among young, healthy people
Acute hypotension may indicate shock
Resting Blood PressureHypertension is high blood pressure.Damages blood
vessels, which may lead to clots and atherosclerosis
Causes heart to work harder, leading to enlarged heart that will eventually weaken
Hypertension can be a positive feedback cycle – why?
Capillary ExchangeCapillary exchange is the movement of
substances (water, gases, nutrients, wastes, etc.) between capillaries and the interstitial fluid of tissues
Capillaries have special features which increase their permeability:Intercellular clefts: spaces between cells
Fenestrations: very thin membrane- covered spots, or pores
Capillary ExchangeCapillary exchange is the movement of
substances (water, gases, nutrients, wastes, etc.)
Capillaries have special features which increase their permeability:Intercellular clefts: spaces between cells
Fenestrations: very thin membrane -covered spots, or pores
Clefts and fenestrations are most important for the diffusion of what kinds of substances?Water, and other lipid-insoluble substances
What can get through without their help?O2, CO2, fats
Capillary ExchangeCapillary exchange is the movement of
substances (water, gases, nutrients, wastes, etc.)
Capillaries have special features which increase their permeability:Intercellular clefts: spaces between cells
Fenestrations: very thin membrane -covered spots, or pores
What type of capillaries don’t have fenestrations or intercellular clefts?Capillaries in the brain – work with astrocytes to form blood-brain barrier
Capillary ExchangeDifferences in pressure in blood pressure and
osmotic pressure help fluids move out of capillaries at the arterial end and into capillaries at venous end.
Watch me!
ClosureWhat was our objectives, and what did we
learn?What was our learner profile trait and how
did we demonstrate it?How does what we did today tie to our unit
question?