Vascular Physiology Flashcards
Humans have
A closed circulatory system
How are vessels that form a continuous space bound?
Plasma membranes and basement membranes
__carry blood away from the heart
Arteries
____ carry blood to the heart?
Veins
What lies between arteries and veins?
Capillaries
__are the site of material exchange
Capillaries
What are the three layers that line the walls of veins and arteries?
Tunica intimia, tunica media, and tuinca externa
What is the tunica intima composed of
Endothelium (simple squamous epithelium) Subendothelial layer (basement membrane and loose connective tissue
What is tunica media composed of
circularly arranged smooth muscle cells
What is tunica externa composed of?
loose connective tissue with nerves blood vessels (vasa vasorum) and lymphatic vessels
How do the walls of veins and arteries differ?
Arteries have internal and external elastic lamina on either face of the tunica media
The tunica media in arteries are thicker
Tunica intima of veins folds that extend into the lumen and form valves
What are the different types of arteries?
Elastic (conducting) arteries
Muscular (distributing) arteries
Arterioles
Which type of artery is nearest the heart?
Elastic (conducting) artery
Which type of artery makes up the bulk of the larger arteries of the body?
Muscular (distributing) artery
Which type of artery is the smallest?
Arterioles
Which type of artery feeds directly into capillaries?
Arterioles
What are the different types of veins?
Venules; and Veins
Which type of vein allows for the passage of leukocytes?
Venules
Which type of vein prevents the back flow of blood?
Veins
What is the smallest vessel?
Capillaries
Which vessel only consists of Tunica intima?
Capillaries
What smooth muscle like cells are on the outer wall of the capillary?
Pericytes
What are the three types of capillaries?
Continuous capillaries; Fenestrated capillaries; Sinusoidal capillaries
What are the most common type of capillary:
Continuous capillaries
What do the tight junctions in continuous capillaries do?
They prevent movement of cell sized bodies out of the lumen by active transport
Where are fenestrated capillaries found?
they are found wherever passive flow of materials out of the capillary is required
What allow small solutes to move freely in fenestrated capillaries?
Holes or fenestrations
Where are fenestrated capillaries found in the body?
Kidneys; Intestines; and Endocrine Organs
Where are sinusoidal capillaries found?
Wherever protein sized molecules and even cells must permeate the walls
Where are the large openings in sinusoidal capillaries found ?
The endothelium and basement membrane
Where are sinusoidal capillaries found in the body?
In bone marrow; some endocrine glands; the choroid plexi; the liver; and lymphoid organs
What are the interweaving networks where capillaries are found called?
Capillary beds
Where do capillaries in a bed arise from?
A single metarteriole that passes through tthe bed (vascular shunt)
What are precapillary sphincters?
bands of smooth muscle that can close off the proximal end of each capillary and divert to the shunt
What is an anastomosis?
Any arrangement of blood vessels that allows an alternate pathway for blood to take around a blockage.
What do arterial anastomoses involve?
alternate supply of organs by arteries
What are vascular shunts?
arteriovenous anastomoses
Which type of anastomoses is the most common?
Venous anastomoses
What are the physical properties that are the most important to physiology ?
Blood Flow (F) Blood Pressure (P) Resistance (R)
What is blood flow?
The rate at which a given volume of blood flows through a region in a given time
What is blood pressure?
the force exerted by the blood on a given area of a vessel wall
What is resistance?
The force exerted that opposes the flow of blood along a given stretch of blood vessels
What is an important factor in the perfusion of the tissues?
Blood flow
As perfusion increases the rate at which oxygen and nutrients reaches the tissues ?
increases
What is equivalent to CO
the systematic flow of blood
What does blood pressure determine?
how rapidly material exchange across the capillary walls will take place
What determines the blood flow along vessels?
The difference in blood pressure form one point to the next along a given length of vessels
How does fluid flow?
from areas of high pressure to areas of low pressure
What determines resistance?
Blood Viscosity; Vessel Length; and Vessel diameter
What is the main regulator of resistance?
Vessel diameter
What does vessel length do?
increasing length increases surface area and thus friction between the blood and the wall
What is blood viscosity?
the resistance to flow by the fluid itself
What allows for the diameter of a vessel to change?
Smooth Muscle
Why is resistance important?
for regulation of local blood flow
What causes resistance?
Fluid
When a vessel is dilating what happens to the resistance?
it decreases
When a vessel is constricting what happens to the resistance?
it increases
What is the change in blood pressure most important for?
Systematic movement of blood
When resistance is up flow is
decreased
When pressure is up flow is
increased
Why can’t blood pressure be high through out the whole system?
because blood will not flow
Where does blood pressure reach it’s maximum ?
In the Aorta
When does blood pressure reach its maximum?
During the contraction of the left ventricle (Systole)
The beating of the heart and the pressure caused by smooth muscle in teh vessel walls are largely irrelevant to what?
The pressure differences in the venous system
When diastole occurs blood pressure is where?
at its lowest
When systole occurs blood pressure is where?
at its highest
What determines arterial blood pressure?
The elasticity of the vessels and the volume of blood forced into them by the heart
What dampens the pulse of vessels?
its elasticity
How do you maintain blood pressure?
smooth muscle in the arteries pushes on the blood
What is normal for systolic pressure?
120 mm Hg
What is normal for diastolic pressure?
80 mm Hg