3 Blood Pressure Flashcards
What are 3 different capillary types?
Continuous
Fenestrated
Sinusoid
Where are continuous capillaries found?
Continuous capillaries are the most common type of capillaries found in tissues such as muscles, skin, lungs, and the central nervous system. Their role is to facilitate the exchange of gases, nutrients, and waste products between the blood and surrounding tissues. These capillaries have a continuous endothelial lining with tight junctions between cells, limiting the passage of large molecules while allowing smaller ones, like water, ions, and glucose, to pass through via diffusion. The tight junctions help maintain blood-brain barrier integrity in the brain and regulate the selective permeability in other tissues.
Where are fenestrated capillaries found?
Fenestrated capillaries are specialized capillaries found in organs that require rapid exchange of larger volumes of substances, such as the kidneys, intestines, and endocrine glands. These capillaries have endothelial cells with small pores (fenestrae) that allow for the passage of larger molecules like hormones, nutrients, and waste products, as well as water, while still maintaining some level of selectivity. In the kidneys, for example, fenestrated capillaries are involved in filtration, allowing for the rapid removal of waste from the blood. In the intestines and endocrine glands, they facilitate nutrient absorption and hormone secretion.
Where are sinusoid capillaries found?
Sinusoid capillaries are specialized, wide, and irregularly shaped capillaries that allow for the free exchange of large molecules and even cells between the blood and surrounding tissues. They are found in organs involved in the production and filtering of blood, such as the liver, spleen, and bone marrow.
The endothelial lining of sinusoid capillaries is discontinuous, with large gaps that permit the movement of larger substances, including blood cells and proteins, in and out of the bloodstream. In the liver, for example, they facilitate the exchange of nutrients, waste, and blood cells, essential for processes like detoxification and blood cell formation.
What does flow depend on?
Pressure difference
Resistance of the vessel
What is the equation of Ohm’s Law and purpose?
Calculate Flow (Q)
Q = ( Pressure at beginning - Pressure at end of vessel ) / Resistance
What is Poiseulle-Hagen Formula and its purpose?
Calculate resistance
R = ( 8 x viscosity x Length ) / pi x r^4
What is the equation for mean arterial pressure?
Cardiac output x total resistance
What mainly causes total peripheral resistance?
Arterioles are the main site of resistance because of such a small radius
What is capacitance?
Capacitance refers to the ability of blood vessels, particularly veins, to expand and hold a large volume of blood without a significant increase in pressure.
Veins are considered “capacitance vessels” because they store blood and help regulate blood volume distribution in the body.
The high compliance of veins allows them to accommodate large changes in blood volume with minimal changes in pressure.
This property plays a key role in maintaining cardiovascular stability, especially during changes in body posture or blood volume.
How is capacitance reduced?
Contraction of veins reduces capacitance
Blood volume in arterioles is small, so constriction does not change capacitance much
What affects total peripheral resistance the most?
Constriction of arterioles increases total peripheral resistance
Resistance in veins is small, so venoconstriction does not change TPR much
Explain capillary exchange
Explain the lymphatic circulation
Name 4 causes of oedema
Increase in venous pressure
Decrease in oncotic pressure
Decrease in lymphatic flow
Increase capillary permeability
