Page 12 - 15 Flashcards
(19 cards)
What is vasomotor control?
Vasomotor control refers to the regulation of blood vessel diameter by the autonomic nervous system, particularly through the contraction and relaxation of smooth muscle in the walls of blood vessels. This process helps regulate blood pressure and blood flow to different parts of the body based on the body’s needs.
What are precapillary sphincters?
Precapillary sphincters aid in blood redistribution. They are tiny rings of muscle located at the opening of capillaries.
What is vasoconstriction?
Vasoconstriction is when precapillary sphincters contract and blood flow is restricted through the capillary,
What is vasodilation?
Vasodilation is when precapillary sphincters widen and relax, causing blood flow to increase.
What is the importance of precapillary sphincters?
Vasomotor control ensures that tissues are provided with the necessary oxygen and nutrients without have wastage.
What is cardiac output at rest?
Cardiac output = 5 litres per minute
80% of Q goes to organs so precapillary sphincters are vasodilated
20% of Q goes to skeletal muscles so sphincters are vasoconstricted
What is cardiac output during intense exercise?
Cardiac output = 40 litres per minute
20% of Q goes to the organs so precapillary sphincters are vasoconstricted
80% of Q goes to skeletal muscles so sphincters are vasodilated
What is blood pressure?
Blood pressure is the force exerted by the blood against the blood vessel wall.
What is the formula for blood pressure?
Blood pressure - blood flow x resistance
What is systolic pressure?
Ejection of the blood by ventricles contracting creates a high-pressure pulse of blood, which is systolic pressure.
What is diastolic pressure?
The lower pressure as the ventricles relax is diastolic pressure.
Where is blood pressure measured?
Blood pressure is measured at the brachial artery (in the upper arm) using a sphygmomanometer.
What is the average blood pressure?
120/80 mmHg (mm of mercury)
120 = systolic pressure
80 = diastolic pressure
What is blood pressure mostly affected by?
The blood pressure in the various blood vessels is largely dependent on the distance of the blood vessel from the heart.
How does blood pressure change with exercise?
What does blood consist of?
Blood consists of 45% blood cells and 55% plasma.
How is oxygen transported?
- 97% is transported within the haemoglobin to form oxy haemoglobin.
- 3% within blood plasma.
How many oxygen molecules can haemoglobin carry?
Haemoglobin can carry up to 4 oxygen molecules at one time (8 oxygen atoms).
How does carbon dioxide travel?
- 70% combines with water within red blood cells as carbonic acid.
- 23% combines with haemoglobin to form carbaminohaemoglobin.
- 7% dissolves in plasma.
