blood pressure Flashcards
What is systolic pressure?
pressure in system when heart contracts- area of high pressure
What is diastolic pressure?
pressure when heart relaxed- blood vessel pressure drops
What do you measure blood pressure in?
mmHg
where do you measure blood pressure in dogs?
Artery, canul
How do you measure blood pressure in dogs?
Take a chorotid artery
Put a canula in it and connect to tube which is connected to a column mercury
When the heart contracts it will push blood against the column of mercury- makes the column of mercury go up
When the heart relaxes- the column of mercury goes down
How do you measure blood pressure in humans?
using a sphygmomanometer
- Wrap a cuff around arm
- Cuff is attached to the bulb/pump
- Inflate the cuff , putting pressure on the breakel artery, which is a superficial blood vessel in the upper arm
- apply enough pressure to collapse that artery
- When you have collapsed that artery- you are above the systolic pressure
- Release pressure from cuff, until that point where some blood starts to flow= systolic pressure
- The more air you let out the bag, more and more blood flows through, you are not constricting blood flow or collapsing artery= below diastolic pressure
- Determine the pressure when blood vessel first starts opening which is systolic pressure, and the pressure when the blood vessel is not collapsed at all= diastolic pressure.
What are the sounds of Korotkoff?
the systolic and diastolic pressures correspond to the pressures at which a sound is first heard( systolic) and when it dies away.(diastolic)
What does a stethoscope do when you measure blood pressure?
put just below the cuff on breakel artery,
normal blood flow of muscle makes no noise- as it flows smoothly
Decrease pressure in cuff, some blood is starting to flow through, you will hear a soft tapping= systolic pressure
Decrease pressure even more, more and more blood starts to flow, makes a continuous rushing sound, then the sound dies when there is no turbulent blood flow and no constricting vessel which means you are at the Diastolic pressure.
How do you determine blood flowing?
Using a stethoscope- from its sounds that it makes
How do you write the blood pressure?
systolic/diastolic
What is the average blood pressure?
120/80 mmHg in major arteries
e.g. vena cava
Why does the measured blood pressure vary?
As its highest and its greatest variation is in the major arteries near the heart such as the aorta and large arteries and then lowers at small arteries and arterioles
However then by the time the blood returns to the heart via the vena cava, the pressure is almost 0(drops) and variation gets less due to being so far from the pump and heart and the elastic nature of veins and blood vessels which will even out the blood flow.
How does blood pressure vary?
- From person to person (inter-individual)
- With age.
- Depend on what you are doing or feeling (intra-individual )
What is the bp formula?
cardiac output x peripheral resistance
What is cardiac output?
force of cardiac contraction
What is peripheral resistance?
diameter of blood vessels - of vessels are narrow blood pressure is high
What are the 2 main things blood pressure depends on?
- How hard the heart is contracting
- How wide the blood vessels are
why is there a rise in bp with age ?
loss of elasticity in blood vessel( arteriosclerosis )resulting in raised peripheral resistance
while cardiac output stays same
What is the structure of blood vessels?
Veins- bring blood to the heart
Arteries- take blood from the heart
Capillaries- gas and nutrient exchange
What happens when blood pressure increases?
Blood vessels constricting- blood pressure increases
Heart contracts harder- cardiac output increases- blood pressure increases
What happens when blood pressure decreases?
Blood vessels dialate- blood pressure down
cardiac output decreases
What happens with blood pressure if age increases? Example?
the rise in mean blood pressure with age is the result of a loss of elasticity in the blood vessels (arteriosclerosis), resulting in raised peripheral resistance.
What are the mechanisms which regulate arterial blood pressure?
- rapid
- longterm
What is an example of a fast Nervous mechanism of controlling blood pressure?
Baroreceptors- which respond to an increase in blood pressure
- it relies on nerves
- important