Cardiovascular 4 Flashcards
BP (23 cards)
Definition
Reflects the peak arterial pressure resulting from ventricular contraction
systolic pressure
Definition
Represents the arterial pressure of blood during ventricular relaxation
Diastolic pressure
How is PB reported?
Systolic/Diastolic (120/80)
Definition
Difference between systolic and diastolic pressure
Pulse pressure
What is the ideal pulse pressure?
25% of the systolic pressure
Definition
Mean Arteriol pressure
average pressure of blood in the arteries
How do you approximate mean arterial pressure?
- add 1/3 of pulse pressure to the diastolic pressure
or - add 1/3 systolic pressure to 2/3 of diastolic pressure
go over calculations
What are th 5 main variables which affect blood flow and BP?
- Cardiac ouput
- compliance
- volume of the blood
- viscosity of the blood
- blood vessel length and diameter
What is the relationship between CO and BP?
Proportional
inc CO will increas BP
What are some factors that will increase CO and thus increase BP?
- sympathetic stimulation
- epinepherine
- norepinepherine
- thyroid hormones
- increased Ca2+
What are some factors that will decrease CO and thus decrease BP?
- parasympathetic stimulation
- altered K+ levels
- decreased Ca2+
Definition:
Cardiac output
measurment of blood flow from the heart through the ventricles
Definition
Compliance
ability of a vessel to expand to accomodate increased content
Are veins or arteries more compliant?
Veins
What happens if blood volume decrease by >20%? How might this happen?
Pressure and flow decrease
- dehydration
- vomiting
- severe burns
- diarrhea
- bleeding
What happens if blood volume increases? How might this happen?
Pressure and flow increase
- retention of water and sodium
What are the 2 main components of blood viscosity?
formed elements and plasma proteins
How is vessel length related to BP?
Proportional to resistance, longer vessels have greater ristsance causing lower flow (lower BP)
Poiseuille’s Law
resistance is inversly proportional to the radius of the blood vessel raised to the 4th power (R=1/r^4)
How will resistance to flow change if a artery or arteriol constricts to one-half of its original radius?
Resistance to flow will increase 16 times
What is the skeletal muscle pump used for?
To be able to increase the pressure in the veins through contraction of the surrounding skeletal muscles
How does the respiartory pump aid blood flow through the veins of the thorax and abdomen?
During inhalation, volume of the thorax increases and compresses the abdominal cavity
This increases volume, decreases air pressure with the thorax enebaling us to inhale
As pressure within the thorax drops, thoracic vein BP falls below pressure in abdominal veins
This causes blood to flow along its pressure gradient from veins outside the thorax where pressure is higher into the thoracic region where pressure is now lower
This promotes return of blood from thoracic veins to the atria
During exhalation, air pressure increases in the thoracic cavity causing thoracic vein to also increase. This increases velocity of blood flow into the heart
Go over
How does atria pressure play a role in venous return?
During diastole, atrial presssure is very low, allowing for blood to flow in
