Vascular System. Flashcards
Blood Vessels. Venous Return. Vascular Shunt Mechanisms. AVO2 Difference. Bohr Shift.Redistribution of Blood. Starling's Law.
List the Characteristics of Arteries.
Narrow Lumen.
No Valves.
High Pressure.
Thick, Muscular Walls.
Smooth Inside Layer.
What is the Function of Arteries?
Take blood away from the heart.
List the Characteristics of Veins.
Wide Lumen.
Valves,
Low Pressure.
Thin Walls.
No Smooth Layer.
What is the Function of Veins?
Bring blood towards the heart
Define Valves.
Prevent the backflow of blood.
Define Venous Return.
Blood returning back to the heart in the veins.
List the Venous Return Mechanisms.
Pocket Valves.
Skeletal Muscle Pump.
Respiratory Muscle Pump.
Smooth Muscle.
Suction Pump at Right Atrium.
Gravity.
Describe Pocket Valves.
Allow one-way blood flow, and close to prevent back flow.
Describe Skeletal Muscle Pump.
As muscles contract.
Squashes the veins.
Increases pressure in the vein.
Forces blood out towards the heart.
Describe Respiratory Muscle Pump.
Changes in thoracic and amdominal pressure when breathing in and out.
Squash the surrounding veins.
Increases pressure in the vein.
Forces blood out towards the heart.
Describe Smooth Muscle.
Veins have thin walls, but the muscle that is there can contract/twitch to increase pressure
Describe Suction Pump at Right Atrium.
As right atrium relaxes, this pressure change ‘sucks’ blood in.
Describe Gravity.
If above the heart.
During exercise, there is an increase in Venous return. This means…
Greater filling of the heart.
Cardiac muscles stretch more.
The resulting force of contraction is increased.
Increased stroke volume/ejection fraction.
List Vascular Shunt Mechanisms.
Vasodilation.
Vasoconstriction.
Define Vasodilation.
Lumen of the blood vessel gets wider.
Why does Vasodilation happen in the Working Muscles?
The working muscles require more oxygen to produce more energy.
So, blood flow is increased to meet this increase in oxygen demand.
Why does Vasodilation happen at the Heart?
The heart needs a greater supply of oxygen because it works harder.
Why does Vasodilation happen in the Skin?
Blood is directed to the skin to cool the body down. By being nearer the skin, the blood can cool via convection of the outside air and radiation closer to the surface.
Define Vasoconstriction.
Lumen of the blood vessel narrows.
Why does Vasoconstriction happen in the Digestive Organs?
During exercise, the priority is not on digesting food, but on providing blood and oxygen to the places that need it.
Define AVO2 Difference.
The difference in oxygen content between the blood in the arteries and blood in the veins.
Explain what happens to AVO2 following the onset of Exercise.
During exercise, our muscles need more oxygen to keep up with the increased demand.
AVO2 Increases because our muscles extract more oxygen from the blood.
Define Bohr Shift.
A downwards and right shift of the oxyhaemoglobin dissociation curve (any given place/point).
Haemoglobin is less saturated with oxygen.
List the Effects of Bohr Shift during Exercise.
Increased demand for Oxygen.
Increase in Temperature.
Increase in Acidity.
Increase in CO2.
Describe the Increased demand for Oxygen.
Tissues take more oxygen out of the haemoglobin, which is why there is less on the haemoglobin.
Describe the Increase in Temperature.
In hotter temperatures, oxygen dissociates from haemoglobin more readily.
Describe the Increase in Acidity.
Exercise causes a little bit of acidity, which denatures the haemoglobin, therefore oxygen dissociates more readily.
Describe the Increase in CO2.
Haemoglobin has a higher affinity for CO2 than oxygen.
More CO2 is produced during exercise, creating carboxyhaemoglobin instead.
Describe how the body redistributes blood to the skeletal muscles during exercise.
The body redistributes blood to the skeletal muscles to provide them with oxygen and nutrients. This is because the muscles need more energy and oxygen to perform physical activity.
The heart pumps more blood, and the blood vessels in the muscles dilate to allow for increased blood flow. This helps deliver oxygen and nutrients to the working muscles and remove waste products like carbon dioxide.
