Circulation Flashcards
Capillary exchange
- only in capillaries
- materials leave blood and diffuse into the interstitial fluid then into body cells
- RBC, platelets, and plasma proteins can’t pass through walls of capillaries (impermeable)
What affects the net pressure of the capillary?
- BP (hydrostatic pressure): higher at arterial end of capillary, due to pumping action of heart
- Osmotic pressure: mov. of fluid into capillary, due to high con. of plasma proteins. Not affected by the end of the capillary
hemorrhage
- vast reduction in blood volume
- net fluid pressure is from the interstitial fluid into the capillaries due to the low BP
inflammation/allergic reactions
- “endangered” cells release histamine which changes the permeability of the capillary wall
- plasma proteins and white blood cells can leave the capillary and enter the interstitial fluid due to low osmotic pressure
Starvation
- body uses plasma proteins as an energy source
- tissue swelling due to excess fluid movement into the interstitial fluid
In veins, movement of blood is dependant on
- skeletal muscle contraction
- one way valves preventing backflow of blood
- vasoconstriction for when BP is low
- breathing
Peripheral Resistance
- restriction of blood flow due to friction (blood sliding along vessel walls)
- more common in large blood vessels and ones further (on periphery) of the heart
Peripheral Resistance is affected by what?
1. Vasomotor changes (vasoconstriction increases vasodilation decreases) 2. Elasticity of blood vessels (less elastic increases PR) 3. Viscosity of blood (dehydration/too many RBC increase PR) 4. Total blood volume
BP cuff
- sphygmomanometer
- the instrument used to measure BP
- measures systolic/diastolic (relax) pressure
- measurements given as systolic pressure/diastolic pressure (ex. 120/80)
Steps to measuring blood pressure (AILS SRD)
- apply sphygmomanometer to brachial artery, and inflate w/ air until blood flow is cut off (~160 mmHg)
- Listen to the point below the sphygmomanometer w/ stethoscope
- Slowly release pressure on brachial artery
- first sounds heard – systolic pressure
(avg. reading is 120 mmHg)
blood spurts through the artery as pressure on arm=systolic pressure - continue to slowly release pressure on brachial artery
- sounds become muffled and disappear—diastolic pressure
(avg. reading is 80 mmHg)
Range of healthy BP
100/70-120/80
Range of a hypotensive BP
90/60 and lower
Hypotensive means low BP
Range of a hypertensive BP
140/90 and higher
Hypertensive means high BP
What is the range of a healthy pulse and what factors does it depend on?
60 to 100 beats per minute
- age
- weight
- level of fitness
- gender
- lifestyle
If your lifestyle includes regular exercise, your heart muscle is _______. Therefore, your stroke volume will be _______
so the HR of a fit person will be _______ to produce the _______ cardiac output
Strong; greater; less; same
What is the formula for Cardiac Output
Cardiac Output = Stroke Volume X Heart Rate
Tachycardia
- heart is beating faster than normal
- could lead to heart not effectively pumping blood
Bradycardia
the heart is beating slower than normal
could result in a lack of oxygenated in the body
Heart murmur
- caused when a valve in heart does not close completely and blood flows back through the valve
- produces gurgling sound – detected by stethoscope
What sound does a heart make when it beats?
lubb-dubb
- atria walls contract and force blood into the ventricles through the tricuspid/bicuspid valves
- when the valves close, a “lubb” sound is produced
- ventricle walls contract and force blood into the arteries through the semilunar valves
- when valves close with ventricular relaxation, a “dubb” sound is produced
