L12 Flashcards
describe venous return
- Is the blood flow returning to the heart
CO = VR
what are 3 mechanisms for pumping blood back to the heart
pressure gradient
skeletal muscle pump
respiratory pump
describe the pressure gradient
-Due to pressure generated by contraction of left ventricle
-The pressure difference between venules + RV causes venous return
describe skeletal muscle pump
§ Ensure blood goes to heart
□ Standing- both valves opens
Muscles compress the vein
® Distal valve closes
® Blood pushed towards heart
Muscles relax + because of pressure difference
® Distal valve opens
® Proximal valve closes
describe the respiratory pump when inhaling/exhaling
§ Compression/depression of veins
§ Inhalation
□ Diaphragm moves down
□ Increases pressure on abdominal cavity
□ Decreases pressure in thoracic cavity
□ Compression of veins pushes blood towards thoracic cavity
§ Exhalation □ Pressure reverse in 2 cavities Valves in veins close: prevent blood flow back to abdominal veins
describe checking pulse circulation
○ Travelling pressure wave (not actual blood)
○ Created by alternative expansion/recoil of elastic arteries after systole of LV
○ Felt at arteries that can be compressed again bone/other structures
○ Most common artery for this is the radial artery
○ Normal pulse rate = 70 to 80 bpm
○ Tachycardia- heart speeds up (over 100bpm)
○ Bradycardia- heart slows down (under 50 bpm)
Endurance athletes have bradycardia (isn’t necessarily a bad thing unless TOO slow)
describe BP and define dichotic notch
- BP drops with distance from LV
- BP rises + falls with each heartbeat
- Systole (SBP) = 110mmHg, highest pressure
- Diastole (DBP) = 70mmHg, lowest pressure
- At arterioles, BP has steepest drop
- Dichotic notch= upstroke in pressure, when aortic valve closes
how do sphygmomanometers work
- Sphygmomanometer
○ Once pressure in cuff greater the blood pressure, slowly let pressure out until hits systolic pressure- can hear noise because blood needs to force itself under the cuff
○ Systolic- vessel slightly closed
○ Diastolic- vessel opens, no sound heard
So only hear blood pressure when BETWEEN systolic + diastolic - stethoscope
-
describe pulse pressure
- PP = SP- DP
- Normally around 40mmHg
- Is a measure of good health, because contributes to homeostasis in body systems
how to calculate mean arterial pressure (MAP)
Mean arterial pressure (MAP) = DBP + 1/3(SBP-DBP)
what are the 2 types of hypertension
- 2 types
○ Primary/essential
§ Is 90% of cases
§ Idiopathic- no known cause
§ Correlates with obesity, diabetes,
drugs- nicotine
○ Secondary
§ Secondary to another medical
condition/medication
§ E.g. Kidney disease, cortical disorders, from oral contraceptives, cocaine
what are hypertension risk factors?
age
○ Blood pressure varies with age
§ New-borns- 50/40
§ Children 100/60
§ Adults- 120/80
§ Adults- 150/85
race/family history
○ Genetics
○ Diet
○ Na+ consumption
- Stress
gender
○ Less 65 men, more liekly to get hypertension due to lack of endogenous estrogen
- Above 65 women, post menopause, more likely to get due to hormonal shifts and increase in BMI
lifestyle
○ High salt intake
○ Obesity
○ Poor physical fitness
- Drug consumption
explain methods to manage primary hypertension
- Life style modification
○ Eating
○ Exercise
○ Reduce sodium intake
○ Moderation of alcohol
○ Weight loss§ Eating + sodium have biggest effect § Alcohol least - Weight loss depends
explain angioplasty
- Percutaneous transluminal angioplasty
- Is a procedure used to open blocked arteries caused by coronary artery disease
○ Angioplasty
§ Opening a blocked/narrowed blood vessel using a flexible tube/catheter
§ When tube is in place, inflates ot open blood vessel, restoring blood
○ Stent
Often left behind to help keep artery open
- Is a procedure used to open blocked arteries caused by coronary artery disease
draw the cardiac output diaphragm
REFER TO ONENOTE
